An optical dispensing is an eye care professional who is responsible for fitting and dispensing glasses. The term optician originated in the UK, where it relates to eye care professionals who both prescribe and dispense glasses.
The document discusses measuring interpupillary distance, which is the distance between the centers of the two pupils, and describes various instruments that can be used to measure IPD at both distance and near. It provides steps for measuring binocular distance IPD, monocular distance IPD, and near IPD using a ruler, and includes an example of calculating near IPD using the three-quarter rule based on dioptric demand.
Polarized lenses block certain types of light waves to reduce glare. They work by only allowing vertically polarized light to enter the eye, blocking out horizontally polarized light that causes glare when reflected off smooth surfaces like water or roads. Polarized lenses come in various colors and are useful for activities like driving, boating, and photography by improving contrast and reducing eye strain from glare. While effective at reducing most types of glare, polarized lenses have some limitations like not working as well with snow glare and possibly distorting displays.
This document describes a test used to measure heterophoria at near distance. The test works by having the right eye see a vertical and horizontal arrow while the left eye sees vertical and horizontal lines of numbers. The patient reports which numbers the arrows appear to point to in order to measure any horizontal, vertical, or cyclophoric deviations between the two eyes. Key advantages are that it allows simultaneous measurement of multiple types of phorias and relies on accommodation, though it is subjective and cannot be used if accommodation is impaired.
The document summarizes the boxing system used for measuring eyeglass frames. The boxing system imagines drawing a box around the lens shape with the sides tangent to the edges. Key measurements include the A measurement (eye size), B measurement (vertical size), geometric center, distance between lenses, distance between centers, effective diameter, seg height/drop, temple length, length to bend, and front to bend. These standardized measurements are used to specify frame sizes and fit lenses.
Bifocals are lenses with two optical powers, one for distance and one for near. There are several types of bifocal segments including round, flat top, curve top, ribbon, and Franklin style. Bifocals can be made through fused, one piece, or cemented constructions. When measuring for bifocals, the frame is positioned as it will be worn and the bifocal height is measured from the lower limbus or lid margin using a vertical ruler. This ensures the bifocal segment will be at the proper height for the wearer.
The document provides information on evaluating cases of orthoptics. It discusses evaluating a patient's history, visual acuity, eye movements, sensory status, and degree of strabismus. The evaluation includes assessing visual acuity, refraction, eye alignment using various objective tests like cover tests, assessing binocularity using stereopsis tests, and determining the presence of suppression or abnormal retinal correspondence. The document outlines the various tests used to evaluate motor and sensory functions in patients with strabismus.
This document discusses progressive lenses, including their history, types, features, markings, fitting process, advantages, and disadvantages. It provides details on:
- The four main types of lenses - single vision, bifocals, trifocals, and progressive addition lenses.
- Key features of progressive lenses, including having multiple focal points that change continuously across the lens rather than distinct segments.
- Important temporary and permanent markings on progressive lenses used in fitting, including the fitting cross, distance reference circle, and lateral locator lines.
- The process of accurately relocating the fitting cross from temporary to permanent markings to ensure proper positioning over the pupil.
This document discusses pachymetry, which is the measurement of corneal thickness. It begins by defining pachymetry and explaining its importance in assessing corneal health. Normal corneal thickness ranges are provided. Several techniques for measuring corneal thickness are then described, including ultrasonic pachymetry, specular microscopy, slit scanning pachymetry, OCT, and confocal microscopy. Clinical applications of pachymetry in glaucoma, refractive surgery, and contact lens use are discussed. Factors that influence corneal thickness are also reviewed.
The document discusses measuring interpupillary distance, which is the distance between the centers of the two pupils, and describes various instruments that can be used to measure IPD at both distance and near. It provides steps for measuring binocular distance IPD, monocular distance IPD, and near IPD using a ruler, and includes an example of calculating near IPD using the three-quarter rule based on dioptric demand.
Polarized lenses block certain types of light waves to reduce glare. They work by only allowing vertically polarized light to enter the eye, blocking out horizontally polarized light that causes glare when reflected off smooth surfaces like water or roads. Polarized lenses come in various colors and are useful for activities like driving, boating, and photography by improving contrast and reducing eye strain from glare. While effective at reducing most types of glare, polarized lenses have some limitations like not working as well with snow glare and possibly distorting displays.
This document describes a test used to measure heterophoria at near distance. The test works by having the right eye see a vertical and horizontal arrow while the left eye sees vertical and horizontal lines of numbers. The patient reports which numbers the arrows appear to point to in order to measure any horizontal, vertical, or cyclophoric deviations between the two eyes. Key advantages are that it allows simultaneous measurement of multiple types of phorias and relies on accommodation, though it is subjective and cannot be used if accommodation is impaired.
The document summarizes the boxing system used for measuring eyeglass frames. The boxing system imagines drawing a box around the lens shape with the sides tangent to the edges. Key measurements include the A measurement (eye size), B measurement (vertical size), geometric center, distance between lenses, distance between centers, effective diameter, seg height/drop, temple length, length to bend, and front to bend. These standardized measurements are used to specify frame sizes and fit lenses.
Bifocals are lenses with two optical powers, one for distance and one for near. There are several types of bifocal segments including round, flat top, curve top, ribbon, and Franklin style. Bifocals can be made through fused, one piece, or cemented constructions. When measuring for bifocals, the frame is positioned as it will be worn and the bifocal height is measured from the lower limbus or lid margin using a vertical ruler. This ensures the bifocal segment will be at the proper height for the wearer.
The document provides information on evaluating cases of orthoptics. It discusses evaluating a patient's history, visual acuity, eye movements, sensory status, and degree of strabismus. The evaluation includes assessing visual acuity, refraction, eye alignment using various objective tests like cover tests, assessing binocularity using stereopsis tests, and determining the presence of suppression or abnormal retinal correspondence. The document outlines the various tests used to evaluate motor and sensory functions in patients with strabismus.
This document discusses progressive lenses, including their history, types, features, markings, fitting process, advantages, and disadvantages. It provides details on:
- The four main types of lenses - single vision, bifocals, trifocals, and progressive addition lenses.
- Key features of progressive lenses, including having multiple focal points that change continuously across the lens rather than distinct segments.
- Important temporary and permanent markings on progressive lenses used in fitting, including the fitting cross, distance reference circle, and lateral locator lines.
- The process of accurately relocating the fitting cross from temporary to permanent markings to ensure proper positioning over the pupil.
This document discusses pachymetry, which is the measurement of corneal thickness. It begins by defining pachymetry and explaining its importance in assessing corneal health. Normal corneal thickness ranges are provided. Several techniques for measuring corneal thickness are then described, including ultrasonic pachymetry, specular microscopy, slit scanning pachymetry, OCT, and confocal microscopy. Clinical applications of pachymetry in glaucoma, refractive surgery, and contact lens use are discussed. Factors that influence corneal thickness are also reviewed.
Progressive addition lenses (PALs) provide a gradual transition from distance to near vision without visible lines. PAL designs aim to maximize clear vision zones for distance, intermediate, and near viewing. Key design considerations include lens hardness, symmetry, prescription parameters, and lens surface asphericity. Modern PALs utilize advanced optical modeling and eye tracking technology to minimize distortions and provide natural vision across a wide range of viewing distances. While PALs offer continuous vision without lines, their transition zones may require more eye and head movement compared to single vision lenses.
The document discusses pantoscopic tilt, which is when the bottom of eyeglass frames are angled toward the cheeks. It describes how proper pantoscopic tilt helps maximize the amount of bridge surface resting on the nose. The document also mentions retroscopic tilt, when the bottom of frames is angled away from the cheeks, and orthoscopic tilt, when frames have no angle. Additionally, it explains how lens tilt improves how glasses look and function for patients, and depends on ear and nose bridge heights, requiring frames to be properly adjusted for individual wearers before measurements.
The refractive index is the ratio of the speed of light in a vacuum to the speed of light in a material. Materials with a higher refractive index bend light more and allow for thinner lenses. High index lenses have a refractive index greater than 1.49 for plastics and 1.523 for glass. They provide benefits like thinner and lighter lenses but also have disadvantages like increased chromatic aberration. Common materials used include lanthanum, titanium, and polyurethane.
Troubleshooting bifocals and Market Availability in Nepal
Bifocals in Anisometropia
Prismatic Effect in Bifocal
Bifocal Prescription
Bifocals in High Astigmatism
This document discusses the different parts and types of eyeglass frames. It defines the frame as the portion that holds the lenses in front of the eyes. The key parts are identified as the bridge, eyewire, endpieces, hinges, temples, and nose pads. Different frame materials like plastic, metal, and nylon are described. Various bridge, endpiece, and temple designs are outlined, including saddle, modified saddle, keyhole, and turn back styles. Frame types such as half-eyes, rimless, and combination frames are also summarized.
Keratometry is a technique to measure the curvature of the cornea using a keratometer. A keratometer projects illuminated circles called mires onto the cornea which form reflected images. By measuring the size of the reflected images, the radius of curvature of the cornea can be calculated in two principal meridians. Keratometry is used to measure corneal astigmatism and monitor the shape of the cornea for conditions like keratoconus. Automated keratometers have replaced manual keratometers and can measure corneal curvature more quickly and accurately.
This document summarizes various types of defects that can occur in ophthalmic lenses. It categorizes defects as occurring either in the material of the lens, on the surface of the lens, or from maltreatment of the finished surface. Defects in the material include bubbles, feathers, veins, coloration and strain. Surface defects from production include holes, greyness, polishing burns, waves, rings and generator marks. Maltreatment can cause scratches, chips, bruises and other abuse marks. The document provides detailed descriptions and examples of each type of defect.
Contrast sensitivity is a measure of the ability to detect slight differences in luminance or color. It is tested using sine wave or square wave gratings that vary in spatial frequency and contrast level. Contrast sensitivity is a better predictor of visual function than visual acuity alone, as it can detect losses from conditions like cataracts, glaucoma, and AMD even before acuity is affected. Contrast sensitivity is measured using charts like Pelli-Robson, FACT, and Arden plates that test sensitivity across spatial frequencies. Many ocular and systemic factors can influence contrast sensitivity, including refractive error, age, cataracts, diabetes, glaucoma, and macular diseases. Contrast sensitivity testing provides additional information about visual
Ultrasonography uses ultrasound to image tissues within the body. A-scan ultrasonography provides a one-dimensional view of the eye by measuring the echoes of ultrasound waves. It can be used to detect and measure tumors, assess eye structures for IOL calculation, and interpret pathology. The ultrasound is reflected at interfaces between tissues, appearing as spikes on the display. Immersion techniques provide more accurate measurements than contact techniques by avoiding compression artifacts. Limitations include artifacts, small lesions, missed foreign bodies, and misalignment issues.
This document discusses corneal curvature, thickness, and keratometry. It provides normal values for the cornea, including thickness, diameter, radius of curvature, and refractive index. Keratometry is defined as the measurement of the cornea. It is used to determine corneal curvature, astigmatism, and distortions. The document describes the optical principles and procedure for taking keratometry measurements. It discusses how to interpret the results and potential problems that can occur.
This document discusses aspheric lenses. It begins with a brief history of aspheric lens development from 1909 to 1980. It then covers terminology, the introduction of aspheric lenses which aim to reduce optical aberrations compared to spherical lenses. The document discusses various aspheric lens designs and how they can reduce peripheral aberrations and make lenses thinner. It also covers measuring aspheric lenses, uses of aspheric lenses, and benefits such as reduction of oblique astigmatism and thinner lens designs.
Optical and Non-optical Methods of Measuring Axial Length of EyeRabindraAdhikary
This document discusses various optical and non-optical methods of measuring axial length of the eye. It begins by defining axial length and noting its importance in intraocular lens power calculations. It then describes ultrasonic (A-scan) biometry, the historical standard, and optical biometry techniques like partial coherence interferometry used in devices like the IOLMaster 500. Key advantages of optical techniques are discussed as well as limitations of ultrasound. Details are provided on performing both immersion and non-immersion ultrasound techniques and interpreting the results.
The document discusses lenticular lenses, which have a central area with prescribed power surrounded by a carrier area of little or no power. Lenticular lenses are used for high prescriptions between +10 to -30 diopters. There are several types including aspheric, Welsh 4 drop, and multi-drop plus lenses as well as myodisc and minus lenticular minus lenses. Lenticular lenses provide benefits of reduced weight and thickness compared to standard lenses but can have aesthetic drawbacks when the edge of the aperture is visible. Various manufacturers produce lenticular lenses in different materials and indexes to accommodate a wide range of prescriptions.
Frames for older wearers should be lightweight to prevent pressure sores on the nose and ears as skin loses elasticity with age. The frame bridge must fit correctly and spread weight evenly. Style is still important for older individuals. Sports eyewear standards help protect performance and safety, and require impact resistance and labeling with manufacturer, model, and intended sport(s). Considerations for different sports include helmets, UV protection, prescription adaptations, and frame positioning.
The document discusses Fresnel lenses and prisms. It describes how Fresnel prisms are thinner than conventional ophthalmic prisms but can provide the same optical power due to their array of small angular grooves. The document outlines several medical indications for using Fresnel lenses, including for the treatment of phorias, strabismus, nystagmus, and diplopia. It provides guidance on selecting, applying, cleaning, and caring for Fresnel lenses.
Frame measurements are essential for ordering prescription glasses correctly. The boxing system uses geometric center, lens size (eye size A), depth (B), and width (C) in millimeters. Distance between lenses (DBL) and geometric center distance (GCD) are also in millimeters. Temple length is overall length from center barrel to end. Frames are marked with eye size, DBL, temple length, manufacturer, and country of origin. Safety frames are marked with "Z87". Metal frames indicate gold content in karats.
The document discusses the process of optical dispensing, including defining optical dispensing, measuring frames and lenses, selecting frames based on facial shapes, lens materials and coatings, and the process of laying off, cutting, and edging lenses to fit into frames. Key steps include determining facial measurements, selecting appropriate frames, measuring pupillary distance, marking lenses, cutting lenses to shape using hand or automatic edgers, and fitting the finished lenses into frames.
Dispensing glasses PPT for O.A. 2nd year Vinitkumar MJ
This document discusses frame and lens selection based on occupation and age. Key factors in frame selection include comfort, appearance, safety, and suitability for the person's occupation and lifestyle. Different occupations require consideration of visual needs, hazards, and working conditions. Frame material, size, and lens material should be chosen accordingly. For example, plastic frames and polycarbonate lenses are recommended for drivers and industrial or sports workers due to safety concerns. Progressive or multifocal lenses may be suitable for various occupations requiring vision at multiple distances.
This document provides information and steps for measuring pupil distance (PD) which is important for proper fitting of eyewear. It discusses using a ruler or pupillometer to measure binocular and monocular PD at distance and near. The three-quarter rule for calculating near PD based on add power and distance PD is also explained. Proper fitting of eyewear requires accurate measurement of PD to avoid issues like diplopia and visual discomfort.
The document provides an overview of optical dispensing. It discusses defining optical dispensing and the steps involved, including frame selection based on facial shape, frame measurements, lens measurements, counseling patients on lens materials and coatings, and the process of fitting lenses into frames which involves marking, cutting, and edging lenses.
The document describes the components and uses of a trial box, which is a set of lenses, frames, and accessories used to test vision. It contains trial frames that hold spherical, cylindrical, and prismatic lenses in various diopters for refraction testing. Accessories include occluders, filters, Maddox rods, and near charts for additional exams. The trial box is an essential tool for optometrists to objectively and subjectively refract patients and diagnose vision disorders.
Progressive addition lenses (PALs) provide a gradual transition from distance to near vision without visible lines. PAL designs aim to maximize clear vision zones for distance, intermediate, and near viewing. Key design considerations include lens hardness, symmetry, prescription parameters, and lens surface asphericity. Modern PALs utilize advanced optical modeling and eye tracking technology to minimize distortions and provide natural vision across a wide range of viewing distances. While PALs offer continuous vision without lines, their transition zones may require more eye and head movement compared to single vision lenses.
The document discusses pantoscopic tilt, which is when the bottom of eyeglass frames are angled toward the cheeks. It describes how proper pantoscopic tilt helps maximize the amount of bridge surface resting on the nose. The document also mentions retroscopic tilt, when the bottom of frames is angled away from the cheeks, and orthoscopic tilt, when frames have no angle. Additionally, it explains how lens tilt improves how glasses look and function for patients, and depends on ear and nose bridge heights, requiring frames to be properly adjusted for individual wearers before measurements.
The refractive index is the ratio of the speed of light in a vacuum to the speed of light in a material. Materials with a higher refractive index bend light more and allow for thinner lenses. High index lenses have a refractive index greater than 1.49 for plastics and 1.523 for glass. They provide benefits like thinner and lighter lenses but also have disadvantages like increased chromatic aberration. Common materials used include lanthanum, titanium, and polyurethane.
Troubleshooting bifocals and Market Availability in Nepal
Bifocals in Anisometropia
Prismatic Effect in Bifocal
Bifocal Prescription
Bifocals in High Astigmatism
This document discusses the different parts and types of eyeglass frames. It defines the frame as the portion that holds the lenses in front of the eyes. The key parts are identified as the bridge, eyewire, endpieces, hinges, temples, and nose pads. Different frame materials like plastic, metal, and nylon are described. Various bridge, endpiece, and temple designs are outlined, including saddle, modified saddle, keyhole, and turn back styles. Frame types such as half-eyes, rimless, and combination frames are also summarized.
Keratometry is a technique to measure the curvature of the cornea using a keratometer. A keratometer projects illuminated circles called mires onto the cornea which form reflected images. By measuring the size of the reflected images, the radius of curvature of the cornea can be calculated in two principal meridians. Keratometry is used to measure corneal astigmatism and monitor the shape of the cornea for conditions like keratoconus. Automated keratometers have replaced manual keratometers and can measure corneal curvature more quickly and accurately.
This document summarizes various types of defects that can occur in ophthalmic lenses. It categorizes defects as occurring either in the material of the lens, on the surface of the lens, or from maltreatment of the finished surface. Defects in the material include bubbles, feathers, veins, coloration and strain. Surface defects from production include holes, greyness, polishing burns, waves, rings and generator marks. Maltreatment can cause scratches, chips, bruises and other abuse marks. The document provides detailed descriptions and examples of each type of defect.
Contrast sensitivity is a measure of the ability to detect slight differences in luminance or color. It is tested using sine wave or square wave gratings that vary in spatial frequency and contrast level. Contrast sensitivity is a better predictor of visual function than visual acuity alone, as it can detect losses from conditions like cataracts, glaucoma, and AMD even before acuity is affected. Contrast sensitivity is measured using charts like Pelli-Robson, FACT, and Arden plates that test sensitivity across spatial frequencies. Many ocular and systemic factors can influence contrast sensitivity, including refractive error, age, cataracts, diabetes, glaucoma, and macular diseases. Contrast sensitivity testing provides additional information about visual
Ultrasonography uses ultrasound to image tissues within the body. A-scan ultrasonography provides a one-dimensional view of the eye by measuring the echoes of ultrasound waves. It can be used to detect and measure tumors, assess eye structures for IOL calculation, and interpret pathology. The ultrasound is reflected at interfaces between tissues, appearing as spikes on the display. Immersion techniques provide more accurate measurements than contact techniques by avoiding compression artifacts. Limitations include artifacts, small lesions, missed foreign bodies, and misalignment issues.
This document discusses corneal curvature, thickness, and keratometry. It provides normal values for the cornea, including thickness, diameter, radius of curvature, and refractive index. Keratometry is defined as the measurement of the cornea. It is used to determine corneal curvature, astigmatism, and distortions. The document describes the optical principles and procedure for taking keratometry measurements. It discusses how to interpret the results and potential problems that can occur.
This document discusses aspheric lenses. It begins with a brief history of aspheric lens development from 1909 to 1980. It then covers terminology, the introduction of aspheric lenses which aim to reduce optical aberrations compared to spherical lenses. The document discusses various aspheric lens designs and how they can reduce peripheral aberrations and make lenses thinner. It also covers measuring aspheric lenses, uses of aspheric lenses, and benefits such as reduction of oblique astigmatism and thinner lens designs.
Optical and Non-optical Methods of Measuring Axial Length of EyeRabindraAdhikary
This document discusses various optical and non-optical methods of measuring axial length of the eye. It begins by defining axial length and noting its importance in intraocular lens power calculations. It then describes ultrasonic (A-scan) biometry, the historical standard, and optical biometry techniques like partial coherence interferometry used in devices like the IOLMaster 500. Key advantages of optical techniques are discussed as well as limitations of ultrasound. Details are provided on performing both immersion and non-immersion ultrasound techniques and interpreting the results.
The document discusses lenticular lenses, which have a central area with prescribed power surrounded by a carrier area of little or no power. Lenticular lenses are used for high prescriptions between +10 to -30 diopters. There are several types including aspheric, Welsh 4 drop, and multi-drop plus lenses as well as myodisc and minus lenticular minus lenses. Lenticular lenses provide benefits of reduced weight and thickness compared to standard lenses but can have aesthetic drawbacks when the edge of the aperture is visible. Various manufacturers produce lenticular lenses in different materials and indexes to accommodate a wide range of prescriptions.
Frames for older wearers should be lightweight to prevent pressure sores on the nose and ears as skin loses elasticity with age. The frame bridge must fit correctly and spread weight evenly. Style is still important for older individuals. Sports eyewear standards help protect performance and safety, and require impact resistance and labeling with manufacturer, model, and intended sport(s). Considerations for different sports include helmets, UV protection, prescription adaptations, and frame positioning.
The document discusses Fresnel lenses and prisms. It describes how Fresnel prisms are thinner than conventional ophthalmic prisms but can provide the same optical power due to their array of small angular grooves. The document outlines several medical indications for using Fresnel lenses, including for the treatment of phorias, strabismus, nystagmus, and diplopia. It provides guidance on selecting, applying, cleaning, and caring for Fresnel lenses.
Frame measurements are essential for ordering prescription glasses correctly. The boxing system uses geometric center, lens size (eye size A), depth (B), and width (C) in millimeters. Distance between lenses (DBL) and geometric center distance (GCD) are also in millimeters. Temple length is overall length from center barrel to end. Frames are marked with eye size, DBL, temple length, manufacturer, and country of origin. Safety frames are marked with "Z87". Metal frames indicate gold content in karats.
The document discusses the process of optical dispensing, including defining optical dispensing, measuring frames and lenses, selecting frames based on facial shapes, lens materials and coatings, and the process of laying off, cutting, and edging lenses to fit into frames. Key steps include determining facial measurements, selecting appropriate frames, measuring pupillary distance, marking lenses, cutting lenses to shape using hand or automatic edgers, and fitting the finished lenses into frames.
Dispensing glasses PPT for O.A. 2nd year Vinitkumar MJ
This document discusses frame and lens selection based on occupation and age. Key factors in frame selection include comfort, appearance, safety, and suitability for the person's occupation and lifestyle. Different occupations require consideration of visual needs, hazards, and working conditions. Frame material, size, and lens material should be chosen accordingly. For example, plastic frames and polycarbonate lenses are recommended for drivers and industrial or sports workers due to safety concerns. Progressive or multifocal lenses may be suitable for various occupations requiring vision at multiple distances.
This document provides information and steps for measuring pupil distance (PD) which is important for proper fitting of eyewear. It discusses using a ruler or pupillometer to measure binocular and monocular PD at distance and near. The three-quarter rule for calculating near PD based on add power and distance PD is also explained. Proper fitting of eyewear requires accurate measurement of PD to avoid issues like diplopia and visual discomfort.
The document provides an overview of optical dispensing. It discusses defining optical dispensing and the steps involved, including frame selection based on facial shape, frame measurements, lens measurements, counseling patients on lens materials and coatings, and the process of fitting lenses into frames which involves marking, cutting, and edging lenses.
The document describes the components and uses of a trial box, which is a set of lenses, frames, and accessories used to test vision. It contains trial frames that hold spherical, cylindrical, and prismatic lenses in various diopters for refraction testing. Accessories include occluders, filters, Maddox rods, and near charts for additional exams. The trial box is an essential tool for optometrists to objectively and subjectively refract patients and diagnose vision disorders.
The document describes the components and uses of a trial box, which is a set of lenses, frames, and accessories used to test vision. It contains trial frames that hold spherical, cylindrical, and prismatic lenses in various diopters for refraction testing. Accessories include occluders, filters, charts, and tools like Maddox rods and cross cylinders. The trial box is used for objective and subjective refraction, diagnosing conditions like squint, and assessing binocular vision.
Orthokeratology uses reverse geometry contact lenses to temporarily reshape the cornea overnight and correct refractive errors. It was first reported in 1965 and uses modern reverse geometry lenses made of high Dk materials. Orthokeratology works by inducing peripheral myopic defocus to flatten the central cornea. It is generally used for low to moderate myopia but can also be used for astigmatism and presbyopia. Fitting involves evaluating corneal topography and achieving a fluorescein pattern with central touch and a tear reservoir before overnight wear begins. Orthokeratology has advantages of reversibility and potential to slow myopia progression but requires continued lens wear to maintain effects.
A trial lens set contains spherical lenses from 0.12 to 20.0 diopters and cylindrical lenses from 0.12 to 6.0 diopters. It is the primary device used in refraction and includes lenses, occluders, pinholes, Maddox rods, and prisms. Cylindrical lenses are marked to indicate axis and do not have handles. Accessories like occluders and pinholes come in standard sizes and are used to test each eye separately or reduce retinal blur. Maddox rods form red streaks to detect heterophoria. Trial frames hold the lenses and have markings to properly position cylindrical lenses and accessories for refraction testing.
This document summarizes the components and uses of a trial box, which is a set of lenses and frames used to test vision. It consists of trial frames, spherical and cylindrical trial lenses in various powers, prisms, and accessories like occluders and filters. The trial frames come in full aperture, reduced aperture, and half-eye styles and are designed to hold trial lenses for refraction testing. The lenses, prisms, and accessories allow objective and subjective refraction, measurement of astigmatism and strabismus, and evaluation of binocular vision.
Spherical RGP contact lens fitting and prescribingPabita Dhungel
RGP contact lenses provide better oxygen permeability than soft lenses, making them a good option for higher prescriptions or conditions like keratoconus. Key factors in fitting RGP lenses include assessing the patient's cornea, measuring their prescription, pupil size, and lid characteristics to select the appropriate trial lens. During the fitting, the practitioner evaluates the lens's dynamic movement, static position, centration, and the patient's vision to determine the right lens parameters to order.
Clinical Management of Aphakia and Pseudophakia.pptxAshi Lakher
1) The document discusses the clinical management of aphakia and pseudophakia. It covers the causes, optics, symptoms and signs of aphakia as well as management options including spectacles, contact lenses, and intraocular lens implantation.
2) Management of pseudophakia involves correcting the refractive error after cataract surgery and lens implantation through intraocular lenses. Considerations for lens type and power calculations in adults and children are discussed.
3) Complications of the different management approaches are compared, noting advantages and disadvantages of contact lenses versus intraocular lens implantation. Refractive surgery techniques for correction of aphakia are also briefly mentioned.
Magnification is an important tool in dentistry that improves visualization of small structures. While loupes provide 2-5x magnification, microscopes allow for higher magnification of 6-40x as well as enhanced lighting. The key components of a microscope include the supporting structure, body with eyepieces, magnification changers, objective lens, and light source. Microscopes provide superior magnification, illumination, depth of field, and allow for documentation compared to loupes. Accessories like filters, cameras, and assistant scopes further enhance the utility of microscopes for dental procedures.
This document outlines the protocol for prescribing contact lenses which involves several steps: patient screening to determine suitability, preliminary examinations and measurements, trial lens fitting to determine the final lens specifications, dispensing the lenses with instructions, and follow-up after-care visits. The trial fitting process aims to select trial lenses that closely match the final prescription parameters and involves assessing the fit and vision until a satisfactory fit is achieved. Desired characteristics of a good contact lens fit include centration, adequate movement, complete corneal coverage, comfort, and good stable vision.
SLIT LAMP AND ITS DIFFERENT ILLUMINATION TECHNIQUES.pptxAbhishek Kashyap
This presentation explains in detail about different illumination techniques and filters used in slit lamp examination and the procedure to perform slit lamp examination.
Low Vision Near Systems-Microscopes,Magnifiers & Electronic systemsHarsh Jain
Different Optical devices used in Low vision patients.
Its very important to take proper assessment and calculations for giving Optical devices like Microscopes,Magnifier etc.
The references are given.
The slit lamp bimicroscope allows for high-magnification examination and evaluation of the anterior segment of the eye. It has three main components: an illumination system using a slit of light, an observation system with binocular lenses, and a mechanical system to position the eye. Various illumination techniques like diffuse, direct, and indirect can be used to examine different ocular tissues. The slit lamp has a long history and continues to be the most important tool for anterior segment evaluation, enabling detection of many abnormalities. Accessories can further aid in examination of structures like the retina, angle, and measurement of eye pressure.
The present is on Instrumentation of various microscopes such as compound microscope, stereo microscope, polarized microscope, comparison microscope, fluorescent microscope, dark field microscope, electron microscope and it also discusses about the forensic applications of each microscope briefly.
The document discusses the concept of base curve in ophthalmic lens design. It explains that the base curve is the starting point used to calculate the remaining lens curves. Over time, the definition of base curve has evolved with changes in lens material and design. Modern lenses often employ aspheric surfaces, allowing designers flexibility in choosing the base curve and reducing optical aberrations. Proper base curve selection considers lens prescription, thickness, cosmesis, and optical performance.
Prescribing low vision devices by SURAJ CHHETRISuraj Chhetri
The document discusses prescribing low vision devices, including optical and non-optical devices. It covers prescribing distance optical devices like spectacles, contact lenses, and telescopes. Details are provided on prescribing near optical devices such as microscopes, magnifiers, and closed-circuit television. Non-optical devices and factors to consider in prescribing such as visual needs, age, and cost are also outlined. Examples of calculations for determining magnification needed from telescopes and reductions in brightness are included.
This document discusses thin lenses and their uses. It compares converging and diverging lenses, and how they are used in eyeglasses to correct nearsightedness and farsightedness. Compound microscopes and telescopes use multiple lenses - microscopes have objective and ocular lenses, while telescopes have objective and eyepiece lenses. Eyeglasses hold lenses in a frame to correct vision, while contact lenses are worn directly on the eye.
A lensmeter is an instrument used to measure the optical power of lenses. It works by projecting illuminated lines through a test lens and measuring the lens's back focal length. There are manual and automatic lensmeters. A manual lensmeter consists of an illuminated target, fixed lens, telescope, and adjustable eyepiece. To measure a lens, the user adjusts the eyepiece for clear focus, centers the lens, and turns the power drum until the projected lines come into focus, reading the lens power. Spherical lenses focus both single and triple lines at the same power. Cylindrical lenses require adjusting both the power and axis drums to bring each line type into focus separately.
This document summarizes guidelines for dispensing progressive lenses. It identifies the best candidates as previous progressive lens wearers, emerging presbyopes with low add powers, and highly motivated individuals. It notes that previous bifocal wearers and those with occulomotor imbalances may require consideration. The document outlines the procedure for fitting progressive lenses, which includes selecting a frame, pre-adjusting it, measuring the fitting height and PD, verifying the cut-out, and taking free form measurements. It provides tips for selecting an appropriate frame, including ones that maintain adjustment and avoid large styles that expose the wearer to distortions.
How to Make a Field Mandatory in Odoo 17Celine George
In Odoo, making a field required can be done through both Python code and XML views. When you set the required attribute to True in Python code, it makes the field required across all views where it's used. Conversely, when you set the required attribute in XML views, it makes the field required only in the context of that particular view.
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
Walmart Business+ and Spark Good for Nonprofits.pdfTechSoup
"Learn about all the ways Walmart supports nonprofit organizations.
You will hear from Liz Willett, the Head of Nonprofits, and hear about what Walmart is doing to help nonprofits, including Walmart Business and Spark Good. Walmart Business+ is a new offer for nonprofits that offers discounts and also streamlines nonprofits order and expense tracking, saving time and money.
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Answers about how you can do more with Walmart!"
Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptxEduSkills OECD
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Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
Leveraging Generative AI to Drive Nonprofit InnovationTechSoup
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Reimagining Your Library Space: How to Increase the Vibes in Your Library No ...Diana Rendina
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How to Manage Your Lost Opportunities in Odoo 17 CRMCeline George
Odoo 17 CRM allows us to track why we lose sales opportunities with "Lost Reasons." This helps analyze our sales process and identify areas for improvement. Here's how to configure lost reasons in Odoo 17 CRM
it describes the bony anatomy including the femoral head , acetabulum, labrum . also discusses the capsule , ligaments . muscle that act on the hip joint and the range of motion are outlined. factors affecting hip joint stability and weight transmission through the joint are summarized.
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
3. Definition
• An optical dispensing is subspecialty of
optometry of which includes all
procedures from the time the glass
prescription is presented to the optician
till the patients are on with the pair the
glasses satisfactorily.
Optical Dispensing 3
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4. • Frame selection is often a process of trial and error
can be time consuming.
• Proper assistance in frame selection is especially
important for the type of patient who may be inclined
to accept the first frame presented.
• The best frame for a patient complements his or her
facial structure, requires minimal adjustments, and
will securely hold the lenses in place.
Optical Dispensing 4
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Frame style and cosmetic dispensing
5. Frame selection
• Follow these steps to choose a best stylish eyeglass
frames.
5
Optical Dispensing
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6. Determining facial wrap
• Broadly, there are six face shapes that we
observe around the world.
Oval
Round
Square
Rectangle
Triangular
Heart
6
Optical Dispensing
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7. Frame for Oval Face shape
• Ovel face shape is the most common face
shape and is considered as an ideal one.
• We recommend oversized or rectangular
frames
Optical Dispensing 7
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8. Frame for Round Face shape
• Round faces are usually proportional to width
and length that features your full cheeks and a
broad forehead.
• We recommended rectangular or angular frames
for round face shaped persons.
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9. Frame for square Face shape
• Square faces are characterized by a broad
squares forehead and a strong jaw line.
• We recommended Round or Oval shaped
frame.
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10. Frame for Rectangle face shape
• Rectangle faces are regarded as the elongated
proportion that means a longer, narrower face
and nose, along with the
same strong jaw line and
squares forehead.
• We recommended round
or cat eye shaped frame.
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11. Frame for Triangle face shape
• Triangle face have a narrow forehead, but
wider cheek.
• These faces look the best in top heavy styles
which help balance out the jaw.
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12. Frame for Heart face shape
• Heart shaped faces have a broad forehead and
narrow jaw line or small chin.
• We recommended deep vertical frame shaped
frame.
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14. Datum system
• Previously used system for measuring lenses
was established as a system of reference points
for the frames & lenses so that position of lens
optical centres & bifocal
segment heights would
be consistent.
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15. Boxing System
• In 1962 the optical manufacturers association
adopted the boxing system to provide a standard
for frame and lens measurement that greatly
improved upon the accuracy of previous systems.
• The boxing system is based upon the idea of
drawing an imaginary box around a lens shape
with the box’s sides tangent to the outer most
edges of the shape.
Optical Dispensing 15
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18. • It is measured as the horizontal distance
between the furthest temporal and nasal edges
lens shape of the box.
• This is measured in millimeters.
Optical Dispensing 18
“A” MESURMENT
22.01.2016
19. • It is measured as the vertical distance between
the furthest top and bottom edges lens shape
of the box.
Optical Dispensing 19
“B” MESURMENT
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20. • Frame difference
• Datum Line
• Geometric center
• Distance between lenses
• Distance between Centers
• Effective Diameter
• Segment Height
• Segment drop
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23. • Facial wrap
facial wrap the frame fills properly following
the curved line of the face.
• Pantascopic tilt
Pantascopic tilt is the angle between the normal
to the temple and frame front.
• Vertex distance
Vertex distance is the distance between the front
of the cornia and back of the lens.
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25. PD Ruler Method
• Sit directly opposite the patient (arm’s length)
• Position yourself 40cm in front of the patient.
• Eyes are level.
• Place ruler on the bridge of the patient’s nose
• Hold pen torch under your left eye directed
at the patient’s RE
Optical Dispensing
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26. • The dispenser aligns the zero mark of the
demo lens with the centre of patient’s pupil.
• The PD for distance is read as the mark falling
on the left pupil.
22.01.2016 Optical Dispensing 26
27. The Pupilometer method
• Fast and accurate measurement
for monocular and binocular
PDs.
• The variation between
the visual axes and
pupil center.
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Monocular PD
Binocular PD
Practitioner’s side
Patient’s side
28. Procedure:
Hold the instrument in both hands and rest the pupilometer
on patients face.
Ability to vary working distance from 20cm to infinity
Internal hairline moved until line and corneal reflection are
coincident
Corneal reflection typically located nasal to pupil center (2
to 5 )
Optical Dispensing 28
Pupilometer
22.01.2016
30. Direct pupillary reflex marking
• A pen torch will produce clear corneal
reflections.
• Position yourself 40cm in front of the patient.
• Eyes are level
• Hold a pen light under your left eye, aiming
the light at the patient’s eye.
• Mark the patient corneal reflex in marker.
22.01.2016 Optical Dispensing 30
31. • Mark the patient corneal reflex in marker.
22.01.2016 Optical Dispensing 31
32. Layout card measurement
• Measure monocular PD. The recommended
procedure is the use of a pupillometer.
• Incorrect PD may cause difficulty in using
different zones through the lens.
22.01.2016 Optical Dispensing 32
35. Lens material
Traditionally, people used to prefer glass lenses. But
they have become less popular now due to the
danger of breaking. They are also heavier in weight
than alternatives. These days, CR-39 plastic lenses
are the preferred material for spectacle lenses.
It is safer, cost effective and offers an outstanding
optical quality. some people would be satisfied
with just that-a cheap good quality lens which can
correct vision.
Optical Dispensing 35
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36. • People become more aware, they’ve started
realizing there is more to it than it appears.
Like UV protection, even lighter weight,
Optical Dispensing 36
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37. Lens Coating
• Every good lens has 3-4 coatings,
• Each of a microscopic thickness.
• Most common of coatings is for toughening the
lenses to make it break-resistant.
• Then UV protection coating and Scratch resistant.
• Lastly, there is the anti-reflective coating
Primarily helps in reducing the
effect of reflective light from
bright objects such lamps or
car headlights at night.
Optical Dispensing 37
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38. UV Protection and Polarized lens
This is one of the major deciding factors. UV
exposure has been clinically proven to be an
important cause of cataract because of its
oxidative effects on humans.
Optical Dispensing 38
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39. Photochromatic
• A major breakthrough in the area of absorptive
lenses took place in 1964 with the invention of
corning’s photo gray photo chromatic.
• These lenses darken when exposed to light.
• photochromatics are available in both glass
and plastic material.
22.01.2016 Optical Dispensing 39
40. Tinted lenses
• A tint is usually associated with a certain
quantity and depth of color, the depth of color
is described as density of lens.
• Both glass and plastic lenses can be tinted to
achieve the desired color.
22.01.2016 Optical Dispensing 40
41. Ophthalmic Lens fitting
Laying off
• Before a lens is edged it must be marked so
that cylinder axis if any is set according to
prescription and its optical centre is in correct
position relative to lens shape.
• We use a lenso meter to mark three dots
indicating optical centre position and the
horizontal meridian.
Optical Dispensing 41
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42. • These horizontally placed dots are used to set
the lens on correct axis.
• In case of bifocals and trifocal and trifocals the
three dots should be parallel to top of the
segment.
Optical Dispensing 42
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43. Lens cutting
• Once the lens is layed off it must now be cut
into desired shape.
22.01.2016 Optical Dispensing 43
44. Edging formers
• Shanking tongs were then used
to crumble the edge away until
it roughly resembles eye shape.
Optical Dispensing 44
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46. Flat Edge
• This is the simple form of edge.
• It is mainly used for lenses fitted
to rimless mounts or as an
intermediate stage in the
production of other edge forms.
Optical Dispensing 46
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47. Bevel Edge
• The bevel edge is used for
lenses to be fitted in shall
and full rimmed frames.
• To avoid pressure on the
peak of bevel and the attendant risk of
chipping the lens.
Optical Dispensing 47
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48. Mini Bevel
• The peak of a normal bevel lies approximately
midway between the two surfaces with strong
minus lenses and high cylindrical power.
Optical Dispensing 48
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49. Grooved Edge
• It is simply a flat edge with central groove.
• Used mainly on lenses fitted to spectacles of
the nylon supras or semi rimless types.
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50. Hand Edgers
• A hand edger is still indispensable piece os
equipment although new automatic are being
preferred. For starting ensure that the hand edging
machine in good working condition. It should be set
up with adequate water. Hold the lens is both hands
with convex side up. Rest your hands on the dip tray
and press the lens against the revolving diamond
wheel. Make sure to hold the lens across the wheel
and at a slight upward angle. Now slowly rotate the
lens passing the grip of lens from hand to hand.
Optical Dispensing 50
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51. • After edging match size of edged lens with the
frame. The lens is right when the shape is
exactly like that of the frame to be fitted.
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