Sunglasses & Their UV protection
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UV Rays and your Eyes, The dangers of ultraviolet rays and the eye damage they can cause are well documented. Children sunglasses are important as they spend far more time outdoors in the direct sunlight.
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Vertex distance
- When a minus lens moves closer to the eye, it becomes stronger, and when it moves farther from the eye, it becomes weaker. Magnification and minification are also affected by vertex distance.
- The vertex compensation formula is used to calculate power changes when a lens moves closer or farther from the eye. The power adjustment is equal to the lens power squared divided by 1000, multiplied by the distance of movement in millimeters.
- The effective power of a lens varies with vertex distance and is calculated as the lens power divided by 1 minus the distance in meters multiplied by the power.
Frame types and parts
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.
Lens form
The document discusses different types of lenses based on their curvature and shape. There are two main types: flat lenses, which have one flat surface, and curved lenses, which have curves on both surfaces. Curved lenses include meniscus lenses, which are convex on the front and concave on the back, and toric lenses, where one surface is spherical and the other toroidal. The total power of a lens is calculated by adding the powers of the front and back surfaces. Lens shape refers to the outline and can include round, oval, pantascopic round oval, and upswept shapes.
Recumbent prisms and fresnel prisms
This document discusses recumbent spectacles, which use reflecting prisms to enable people lying flat on their back to read. It describes how Andrew McKie Reid designed the first recumbent spectacles in 1935 using prisms with a 35 degree apical angle to bend vision almost 90 degrees. More recently, thin Fresnel prisms have been used as they are only 1mm thick and can be cut into any shape. The document discusses the optics, advantages and disadvantages of Fresnel prisms, as well as how to apply, clean and prescribe them.
Base curve
The document discusses the base curve of lenses, which is the surface curve that forms the starting point for the remaining lens curve. It describes the importance of selecting the proper base curve, as it determines lens thickness, aberrations, and cosmetics. The document outlines different lens forms including Wollaston, Oswalt, and meniscus, discussing their optical properties. It notes that the best lens form follows mechanical and optical criteria, providing a thinner lens that is lighter in weight with reduced magnification and aberrations.
Polaroid lenses
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.
Polarized lenses
Polarizing lenses reduce glare caused by reflections from surfaces like water, snow, and highways. They work by blocking horizontally polarized light that is reflected from these surfaces, while transmitting regular light. The lenses contain a special filter made of polyvinyl acetate and iodine that absorbs the horizontally vibrating components of light. Polarizing lenses can be made for prescription lenses by mounting the polarizing filter between layers of hard resin or polycarbonate. They provide benefits like reduced driving fatigue and improved visibility for activities like fishing or at the beach.
Spectacles dispensing in children
(1) When dispensing spectacles to children, it is important to ensure comfort and safety. Frames should fit properly without slipping or causing pressure. Plastic frames with saddle bridges are preferable to metal frames. Lenses should be lightweight and high impact resistant such as polycarbonate.
(2) It is important to consider the child's preferences but also "win" the approval of parents by emphasizing safety, comfort, and protection features. Technical factors like UV protection, allergy avoidance, and clear vision should be considered.
(3) Sports spectacles with elastic temples can ensure secure fitting for active children. Regular cleaning and replacement of children's spectacles is recommended due to greater risk of damage.
Recommended
Vertex distance
- When a minus lens moves closer to the eye, it becomes stronger, and when it moves farther from the eye, it becomes weaker. Magnification and minification are also affected by vertex distance.
- The vertex compensation formula is used to calculate power changes when a lens moves closer or farther from the eye. The power adjustment is equal to the lens power squared divided by 1000, multiplied by the distance of movement in millimeters.
- The effective power of a lens varies with vertex distance and is calculated as the lens power divided by 1 minus the distance in meters multiplied by the power.
Frame types and parts
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.
Lens form
The document discusses different types of lenses based on their curvature and shape. There are two main types: flat lenses, which have one flat surface, and curved lenses, which have curves on both surfaces. Curved lenses include meniscus lenses, which are convex on the front and concave on the back, and toric lenses, where one surface is spherical and the other toroidal. The total power of a lens is calculated by adding the powers of the front and back surfaces. Lens shape refers to the outline and can include round, oval, pantascopic round oval, and upswept shapes.
Recumbent prisms and fresnel prisms
This document discusses recumbent spectacles, which use reflecting prisms to enable people lying flat on their back to read. It describes how Andrew McKie Reid designed the first recumbent spectacles in 1935 using prisms with a 35 degree apical angle to bend vision almost 90 degrees. More recently, thin Fresnel prisms have been used as they are only 1mm thick and can be cut into any shape. The document discusses the optics, advantages and disadvantages of Fresnel prisms, as well as how to apply, clean and prescribe them.
Base curve
The document discusses the base curve of lenses, which is the surface curve that forms the starting point for the remaining lens curve. It describes the importance of selecting the proper base curve, as it determines lens thickness, aberrations, and cosmetics. The document outlines different lens forms including Wollaston, Oswalt, and meniscus, discussing their optical properties. It notes that the best lens form follows mechanical and optical criteria, providing a thinner lens that is lighter in weight with reduced magnification and aberrations.
Polaroid lenses
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.
Polarized lenses
Polarizing lenses reduce glare caused by reflections from surfaces like water, snow, and highways. They work by blocking horizontally polarized light that is reflected from these surfaces, while transmitting regular light. The lenses contain a special filter made of polyvinyl acetate and iodine that absorbs the horizontally vibrating components of light. Polarizing lenses can be made for prescription lenses by mounting the polarizing filter between layers of hard resin or polycarbonate. They provide benefits like reduced driving fatigue and improved visibility for activities like fishing or at the beach.
Spectacles dispensing in children
(1) When dispensing spectacles to children, it is important to ensure comfort and safety. Frames should fit properly without slipping or causing pressure. Plastic frames with saddle bridges are preferable to metal frames. Lenses should be lightweight and high impact resistant such as polycarbonate.
(2) It is important to consider the child's preferences but also "win" the approval of parents by emphasizing safety, comfort, and protection features. Technical factors like UV protection, allergy avoidance, and clear vision should be considered.
(3) Sports spectacles with elastic temples can ensure secure fitting for active children. Regular cleaning and replacement of children's spectacles is recommended due to greater risk of damage.
Forms of lenses (Faheem Kv)
This document describes different types of lenses:
1. Convex lenses include equiconvex, biconvex, and planoconvex lenses. Concave lenses include equiconcave, biconcave, and planoconcave lenses.
2. Periscopic lenses have one surface with positive power and one with negative power.
3. Meniscus lenses also have one positively powered surface and one negatively powered surface, but with a greater base curve than periscopic lenses.
Maddox rod, Maddox wing, Bagolini striated glasses, RAF ruler and Prism bar
The Maddox rod test is used to detect heterophoria or heterotropia. It consists of a series of cylindrical lenses mounted in a trial frame that produces an elongated streak of light. When viewed through the Maddox rod, a spot of light appears as a streak. The orientation of the streak indicates whether the eye is deviated vertically or horizontally. The test is easy for patients to understand and perform, and useful for detecting vertical deviations.
Optical prism decentration
The optical center of a lens is the point where light rays pass through without deviation. It is important for the optical center to be directly in front of the pupil for optimum vision. Decentering a lens, or moving it so the optical center is no longer in front of the pupil, introduces a prismatic effect. The amount of prismatic effect, measured in prism diopters, is calculated by multiplying the distance the lens is decentered in centimeters by the lens power in diopters. Decentering a lens with a spherical prescription or cylinder introduces different prismatic effects depending on the orientation of the cylinder axis relative to the direction of decentration.
Frame materials
Cellulose acetate, nylon, and titanium are common materials used for eyeglass frames. Cellulose acetate is lightweight but can cause allergic reactions. Nylon is strong, flexible, and hypoallergenic. Titanium is very lightweight and strong, resistant to corrosion, and hypoallergenic, but more expensive than other materials. Other materials used include aluminum, stainless steel, gold, and plastic materials like polycarbonate. The ideal frame material is lightweight, strong, resistant to corrosion and breakage, non-flammable, inexpensive, durable, adjustable, and non-allergic.
Fitting assessment of soft contact lens
The document discusses the requirements and assessment of soft contact lens fitting. It outlines the characteristics of an optimum fit versus a tight or loose fit, including factors like comfort, centration, movement, tightness on push-up, and peripheral fit. The assessment of fit involves evaluating these factors through tests like observing movement, tightness on push-up, and assessing vision. Common fitting problems like discomfort, inappropriate diameter or fit tightness are also summarized.
Lens material and its propertes
The document discusses different lens materials used in ophthalmic lenses, including their properties and characteristics. It covers natural materials like quartz, glass materials like crown glass and flint glass, and plastic materials like CR-39, polycarbonate, high index plastics, and Trivex. For each material, it provides details on composition, refractive index, Abbe value, advantages and disadvantages. The document aims to educate about different lens materials and their properties for lens manufacturing.
Lens surface coating
This document provides information on various lens surface coatings and their types and purposes. It discusses why coatings are applied, including for protection, appearance, clarity and to prevent fogging. It then describes common coating types like MAR coating, tints, scratch resistant coating, mirror coating, polarized coating and edge coatings. It goes on to explain uncoated lenses, single side coated lenses, hard coatings, hydrophobic/oleophobic coatings, anti-reflection coatings, scratch resistance coatings, clean coats, drive safe coats and coatings that provide protection from blue light. The document provides details on how each of these coating types work and their benefits.
Bifocal lenses: types and principles
Bifocal lenses have two optical powers, one for distance vision and one for near vision. They are useful for presbyopia. There are several types of bifocal lenses including round, flat-top, and executive styles. Benjamin Franklin is credited with inventing the first bifocal lens in the late 18th century by cutting a single lens in half. Modern bifocals are manufactured using various techniques like fusing, cementing, or making from a single piece of plastic or glass. Proper positioning and design of the near segment is important to reduce issues like image jump and chromatic aberration. Bifocals come in many styles and materials to best suit individual needs and prescription requirements.
Electronic Devices for Low Vision Patients
This document discusses different types of electronic devices that can help low vision patients. It describes closed-circuit television/desktop magnifiers, portable video magnifiers, mouse-style magnifiers, and head-mounted magnifiers. CCTV/desktop magnifiers provide adjustable magnification from 3x to 100x but are bulky. Portable video magnifiers are smaller and more portable but have a smaller field of view. Mouse-style devices are handheld. Head-mounted devices like the Vmax provide magnification from 0.8x to 20x and allow viewing at different distances automatically. Electronic magnification devices can help those with conditions like glaucoma and retinitis pigmentosa.
Insertion and removal of rgp contact lens.
This document provides instructions for inserting, centering, and removing rigid gas-permeable (RGP) contact lenses. It describes RGP lenses as semi-soft lenses that allow oxygen to pass to the eye. For insertion, it details cleaning and handling the lens properly before placing it on the eye and blinking to center it. Centering involves using fingertips to nudge the lens into position while looking in different directions. For removal, it outlines either using a blink method by pulling the eyelid tight and blinking, or a two-finger method of pressing the eyelids together to dislodge the lens.
Lensometry (Focimeter)
This document discusses methods for detecting the type and power of lenses. It covers hand neutralization techniques for spherical and astigmatic lenses using convex and concave lenses. It also describes using a Geneva lens measure and manual and automated focimeters. The manual focimeter involves aligning mires to determine spherical and cylinder power of single vision, bifocal, trifocal and progressive lenses. The automated focimeter uses a light beam to precisely measure lens parameters. Both tools have limitations, with the automated version providing more accuracy.
Lensometry.
The document discusses lensometry, which is the process of using a lensometer or lensmeter to measure the optical properties of lenses. A lensometer projects lines that allow optometrists to determine information like the sphere, cylinder, and axis measurements specified in a prescription. It can also verify the accuracy of lenses and detect their type (spherical, astigmatic, prismatic). Lensometers are used to properly fit lenses into frames and ensure prescriptions are correct. The document outlines the history of the lensometer's invention and provides details on its use, parts, manual operation, and the measurements it can obtain for different lens types like bifocals.
Examination of low vision patient
History taking , Visual acuity , refraction , visual field , contrast sensitivity of low vision patient
Lens enhancement considering for prescribing
This document discusses various lens enhancements that can be applied to prescription lenses, including anti-reflection coatings, scratch-resistant coatings, and hydrophobic coatings. It provides details on how each type of coating works and is applied. Anti-reflection coatings reduce unwanted reflections using destructive interference of light waves. They are applied in very thin layers, with precise thickness needed. Scratch-resistant coatings increase the hardness and durability of plastic lenses through additional layers. Hydrophobic coatings create a high contact angle to allow water and oils to bead up and roll off the lens surface.
Astigmatic lens
This document discusses astigmatic lenses, which have non-uniform curvature across their surface resulting in different focal lengths in different meridians. There are two main types: cylindrical lenses, which have one curved and one plane surface, and toric lenses, which are a spherical lens combined with a cylindrical lens. Cylindrical lenses form a line image rather than a point, while toric lenses exhibit rotational movement when tested. The power of astigmatic lenses is measured and expressed based on the spherical and cylindrical components as well as the axis orientation.
Automated phoropter
The phoropter is an instrument used by eye care professionals to measure refractive errors and determine eyeglass prescriptions. The first phoropter was introduced in 1917 and had manual and automated versions. The automated phoropter stores testing data, measures additional eye features, and is easier to operate using buttons. It is adjusted for patient alignment and distance before testing refractive errors like sphere, cylinder, and axis values as well as adding power for near vision. The automated phoropter provides a more comfortable experience for patients compared to manual versions.
Tinted lenses
- Absorptive lenses reduce the amount of transmitted light through absorption. They act as filters and may absorb uniformly or selectively across the spectrum.
- Lenses can be tinted through various methods like adding metallic oxides during manufacturing, surface coating with oxides, or dyeing plastic lenses through immersion in solutions.
- Tint colors like green, grey, and brown provide good contrast and protection from glare, while rose tints reduce eyestrain. Darker tints above 70% are needed for sunglasses, while lighter tints around 10-20% are used for fashion.
Magnification
This document discusses different types of magnification that can help low vision patients see objects more clearly. It describes relative size magnification by making objects larger, relative distance magnification by moving closer, angular magnification using optical devices, and real image magnification. The document provides examples of calculating magnification and outlines best practices for optometrists in prescribing magnification aids to patients based on their visual needs and tasks.
Multifocal contact lens
Multifocal contact lenses can correct both near and distance vision and are an alternative to bifocal glasses for people with active lifestyles. There are several types of multifocal contact lens designs, including soft, gas permeable, and hybrid lenses. The most common design is a diffractive lens with concentric circles of different optical powers. Multifocal contact lenses provide clear vision at multiple distances but may cause glare or hazy vision during adjustment. They also have advantages like less need for extra eyewear but disadvantages such as greater difficulty adapting to them.
Progressive Adition Lens
This document provides information about progressive addition lenses (PALs), including their history, design, markings, fitting process, advantages, and disadvantages compared to bifocal lenses. Some key points:
- PALs were invented in the late 1950s and gradually increased in popularity as an alternative to bifocal lenses that provides clear vision from distance to near without visible lines.
- PAL designs can be "hard", with a rapid progression, or "soft" with a slower progression. Designs also differ in the size and location of distance, near, and intermediate zones.
- Fitting PALs properly requires selecting the right frame size and shape, measuring pupillary distance and fitting heights, and ver
Are prescription sunglasses a good idea?
You may sometimes find yourself driving down the road, sun shining in your eyes, as you search in vain for those clip-on or magnetically attached sun lenses that came with your prescription sunglasses.
At times like these, you might find that prescription sunglasses are much more convenient and more than worth the additional investment.
for more info,visit: http://shop.heavyglare.com
Are prescription sunglasses a good idea?
Prescription sunglasses provide several advantages over regular sunglasses or contact lenses. They are more convenient than trying to attach clip-on lenses to regular glasses or having to switch between glasses and contacts depending on the situation. Prescription sunglasses also offer UV protection and a full range of frame styles and lens options. Unlike contact lenses, they can be safely worn for activities like swimming where contacts pose an infection risk. Prescription sunglasses come with the same variety of styles, designers, and lens treatments like polarization for glare reduction as regular sunglasses.
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What's hot
Forms of lenses (Faheem Kv)
This document describes different types of lenses:
1. Convex lenses include equiconvex, biconvex, and planoconvex lenses. Concave lenses include equiconcave, biconcave, and planoconcave lenses.
2. Periscopic lenses have one surface with positive power and one with negative power.
3. Meniscus lenses also have one positively powered surface and one negatively powered surface, but with a greater base curve than periscopic lenses.
Maddox rod, Maddox wing, Bagolini striated glasses, RAF ruler and Prism bar
The Maddox rod test is used to detect heterophoria or heterotropia. It consists of a series of cylindrical lenses mounted in a trial frame that produces an elongated streak of light. When viewed through the Maddox rod, a spot of light appears as a streak. The orientation of the streak indicates whether the eye is deviated vertically or horizontally. The test is easy for patients to understand and perform, and useful for detecting vertical deviations.
Optical prism decentration
The optical center of a lens is the point where light rays pass through without deviation. It is important for the optical center to be directly in front of the pupil for optimum vision. Decentering a lens, or moving it so the optical center is no longer in front of the pupil, introduces a prismatic effect. The amount of prismatic effect, measured in prism diopters, is calculated by multiplying the distance the lens is decentered in centimeters by the lens power in diopters. Decentering a lens with a spherical prescription or cylinder introduces different prismatic effects depending on the orientation of the cylinder axis relative to the direction of decentration.
Frame materials
Cellulose acetate, nylon, and titanium are common materials used for eyeglass frames. Cellulose acetate is lightweight but can cause allergic reactions. Nylon is strong, flexible, and hypoallergenic. Titanium is very lightweight and strong, resistant to corrosion, and hypoallergenic, but more expensive than other materials. Other materials used include aluminum, stainless steel, gold, and plastic materials like polycarbonate. The ideal frame material is lightweight, strong, resistant to corrosion and breakage, non-flammable, inexpensive, durable, adjustable, and non-allergic.
Fitting assessment of soft contact lens
The document discusses the requirements and assessment of soft contact lens fitting. It outlines the characteristics of an optimum fit versus a tight or loose fit, including factors like comfort, centration, movement, tightness on push-up, and peripheral fit. The assessment of fit involves evaluating these factors through tests like observing movement, tightness on push-up, and assessing vision. Common fitting problems like discomfort, inappropriate diameter or fit tightness are also summarized.
Lens material and its propertes
The document discusses different lens materials used in ophthalmic lenses, including their properties and characteristics. It covers natural materials like quartz, glass materials like crown glass and flint glass, and plastic materials like CR-39, polycarbonate, high index plastics, and Trivex. For each material, it provides details on composition, refractive index, Abbe value, advantages and disadvantages. The document aims to educate about different lens materials and their properties for lens manufacturing.
Lens surface coating
This document provides information on various lens surface coatings and their types and purposes. It discusses why coatings are applied, including for protection, appearance, clarity and to prevent fogging. It then describes common coating types like MAR coating, tints, scratch resistant coating, mirror coating, polarized coating and edge coatings. It goes on to explain uncoated lenses, single side coated lenses, hard coatings, hydrophobic/oleophobic coatings, anti-reflection coatings, scratch resistance coatings, clean coats, drive safe coats and coatings that provide protection from blue light. The document provides details on how each of these coating types work and their benefits.
Bifocal lenses: types and principles
Bifocal lenses have two optical powers, one for distance vision and one for near vision. They are useful for presbyopia. There are several types of bifocal lenses including round, flat-top, and executive styles. Benjamin Franklin is credited with inventing the first bifocal lens in the late 18th century by cutting a single lens in half. Modern bifocals are manufactured using various techniques like fusing, cementing, or making from a single piece of plastic or glass. Proper positioning and design of the near segment is important to reduce issues like image jump and chromatic aberration. Bifocals come in many styles and materials to best suit individual needs and prescription requirements.
Electronic Devices for Low Vision Patients
This document discusses different types of electronic devices that can help low vision patients. It describes closed-circuit television/desktop magnifiers, portable video magnifiers, mouse-style magnifiers, and head-mounted magnifiers. CCTV/desktop magnifiers provide adjustable magnification from 3x to 100x but are bulky. Portable video magnifiers are smaller and more portable but have a smaller field of view. Mouse-style devices are handheld. Head-mounted devices like the Vmax provide magnification from 0.8x to 20x and allow viewing at different distances automatically. Electronic magnification devices can help those with conditions like glaucoma and retinitis pigmentosa.
Insertion and removal of rgp contact lens.
This document provides instructions for inserting, centering, and removing rigid gas-permeable (RGP) contact lenses. It describes RGP lenses as semi-soft lenses that allow oxygen to pass to the eye. For insertion, it details cleaning and handling the lens properly before placing it on the eye and blinking to center it. Centering involves using fingertips to nudge the lens into position while looking in different directions. For removal, it outlines either using a blink method by pulling the eyelid tight and blinking, or a two-finger method of pressing the eyelids together to dislodge the lens.
Lensometry (Focimeter)
This document discusses methods for detecting the type and power of lenses. It covers hand neutralization techniques for spherical and astigmatic lenses using convex and concave lenses. It also describes using a Geneva lens measure and manual and automated focimeters. The manual focimeter involves aligning mires to determine spherical and cylinder power of single vision, bifocal, trifocal and progressive lenses. The automated focimeter uses a light beam to precisely measure lens parameters. Both tools have limitations, with the automated version providing more accuracy.
Lensometry.
The document discusses lensometry, which is the process of using a lensometer or lensmeter to measure the optical properties of lenses. A lensometer projects lines that allow optometrists to determine information like the sphere, cylinder, and axis measurements specified in a prescription. It can also verify the accuracy of lenses and detect their type (spherical, astigmatic, prismatic). Lensometers are used to properly fit lenses into frames and ensure prescriptions are correct. The document outlines the history of the lensometer's invention and provides details on its use, parts, manual operation, and the measurements it can obtain for different lens types like bifocals.
Examination of low vision patient
History taking , Visual acuity , refraction , visual field , contrast sensitivity of low vision patient
Lens enhancement considering for prescribing
This document discusses various lens enhancements that can be applied to prescription lenses, including anti-reflection coatings, scratch-resistant coatings, and hydrophobic coatings. It provides details on how each type of coating works and is applied. Anti-reflection coatings reduce unwanted reflections using destructive interference of light waves. They are applied in very thin layers, with precise thickness needed. Scratch-resistant coatings increase the hardness and durability of plastic lenses through additional layers. Hydrophobic coatings create a high contact angle to allow water and oils to bead up and roll off the lens surface.
Astigmatic lens
This document discusses astigmatic lenses, which have non-uniform curvature across their surface resulting in different focal lengths in different meridians. There are two main types: cylindrical lenses, which have one curved and one plane surface, and toric lenses, which are a spherical lens combined with a cylindrical lens. Cylindrical lenses form a line image rather than a point, while toric lenses exhibit rotational movement when tested. The power of astigmatic lenses is measured and expressed based on the spherical and cylindrical components as well as the axis orientation.
Automated phoropter
The phoropter is an instrument used by eye care professionals to measure refractive errors and determine eyeglass prescriptions. The first phoropter was introduced in 1917 and had manual and automated versions. The automated phoropter stores testing data, measures additional eye features, and is easier to operate using buttons. It is adjusted for patient alignment and distance before testing refractive errors like sphere, cylinder, and axis values as well as adding power for near vision. The automated phoropter provides a more comfortable experience for patients compared to manual versions.
Tinted lenses
- Absorptive lenses reduce the amount of transmitted light through absorption. They act as filters and may absorb uniformly or selectively across the spectrum.
- Lenses can be tinted through various methods like adding metallic oxides during manufacturing, surface coating with oxides, or dyeing plastic lenses through immersion in solutions.
- Tint colors like green, grey, and brown provide good contrast and protection from glare, while rose tints reduce eyestrain. Darker tints above 70% are needed for sunglasses, while lighter tints around 10-20% are used for fashion.
Magnification
This document discusses different types of magnification that can help low vision patients see objects more clearly. It describes relative size magnification by making objects larger, relative distance magnification by moving closer, angular magnification using optical devices, and real image magnification. The document provides examples of calculating magnification and outlines best practices for optometrists in prescribing magnification aids to patients based on their visual needs and tasks.
Multifocal contact lens
Multifocal contact lenses can correct both near and distance vision and are an alternative to bifocal glasses for people with active lifestyles. There are several types of multifocal contact lens designs, including soft, gas permeable, and hybrid lenses. The most common design is a diffractive lens with concentric circles of different optical powers. Multifocal contact lenses provide clear vision at multiple distances but may cause glare or hazy vision during adjustment. They also have advantages like less need for extra eyewear but disadvantages such as greater difficulty adapting to them.
Progressive Adition Lens
This document provides information about progressive addition lenses (PALs), including their history, design, markings, fitting process, advantages, and disadvantages compared to bifocal lenses. Some key points:
- PALs were invented in the late 1950s and gradually increased in popularity as an alternative to bifocal lenses that provides clear vision from distance to near without visible lines.
- PAL designs can be "hard", with a rapid progression, or "soft" with a slower progression. Designs also differ in the size and location of distance, near, and intermediate zones.
- Fitting PALs properly requires selecting the right frame size and shape, measuring pupillary distance and fitting heights, and ver
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Maddox rod, Maddox wing, Bagolini striated glasses, RAF ruler and Prism bar
Maddox rod, Maddox wing, Bagolini striated glasses, RAF ruler and Prism bar
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Are prescription sunglasses a good idea?
You may sometimes find yourself driving down the road, sun shining in your eyes, as you search in vain for those clip-on or magnetically attached sun lenses that came with your prescription sunglasses.
At times like these, you might find that prescription sunglasses are much more convenient and more than worth the additional investment.
for more info,visit: http://shop.heavyglare.com
Are prescription sunglasses a good idea?
Prescription sunglasses provide several advantages over regular sunglasses or contact lenses. They are more convenient than trying to attach clip-on lenses to regular glasses or having to switch between glasses and contacts depending on the situation. Prescription sunglasses also offer UV protection and a full range of frame styles and lens options. Unlike contact lenses, they can be safely worn for activities like swimming where contacts pose an infection risk. Prescription sunglasses come with the same variety of styles, designers, and lens treatments like polarization for glare reduction as regular sunglasses.
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This document discusses various types of lenses and coatings used in eyeglasses. It describes unifocal lenses that provide single vision correction and multifocal lenses like bifocals and trifocals that correct for both distance and near vision. Progressive lenses provide a seamless transition between vision corrections. Hi-index and lightweight lenses reduce thickness. Photochromic lenses darken in sunlight and clear in low light. Polarized and tinted lenses reduce glare. Polycarbonate lenses are impact resistant. Anti-reflective coatings improve vision clarity and comfort.
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Lenses have come a long way from traditional bifocals, and it's always great to keep yourself informed about the new technology. This is some information all about transition lenses, and the science behind them. If you're considering getting transitions lenses, take a look!
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Sunglasses & Their UV protection
- 1. ~ Issued in public interest by Shroff Eye Hospital, Mumbai, India Sunglasses and their UV protection
- 4. UV Rays and your Eyes Extended exposure to UV rays, from staying too long in direct sunlight, could lead to a host of eye problems UV radiation can be categorized into three sets of invisible rays: UVC rays, which are the most dangerous, but so far virtually blocked by the atmospheric ozone layer UVB rays, which can cause dangers ranging from a simple skin tan to even skin cancer UVA rays, which have been linked to the formation of certain types of cataracts.
- 5. The dangers of ultraviolet rays and the eye damage they can cause are well documented.
- 6. So to protect your Beautiful Eyes, you need a pair of good UV-blocking sunglasses and contact lenses
- 7. Do Children require sunglasses? Children sunglasses are important as they spend far more time outdoors in the direct sunlight. Their cornea are crystal clear which allows maximum light to pass through deep in eyes which may cause damage in long run if not taken care.
- 8. Polarized Sunglasses These glasses are meant to reduce the glare from highly reflective surfaces like water, glass, or snow. These glasses deal with such reflective glare conditions because of their vertical polarizing orientation.
- 9. At any angle other than horizontal, polarized sunglasses will filter out some or the entire glare, so that the viewer is saved from potential eye strain due to the reflective surroundings. Polarized glasses are used while driving, fishing, snow skiing
- 10. Regular sunglasses, non-polarized, can also filter out glare. However, regular sunglasses will cause loss of visibility in subtle details, which may not be desirable. Normal sunglasses reduce the intensity of light equally everywhere; polarized glasses work by selectively eliminating the reflection from light that causes dangerous glare conditions.
- 11. Photochromatic /Photochromic glasses These glasses change between dark and light depending on how much ultraviolet light they are exposed to They can be worn both indoors and outdoors as shown in picture Indoors serve simply as regular prescription spectacles, while outdoors they darken to serve as sunglasses This transition is rapid & its caused due to change in UV light
- 12. Prescription Sunglasses People who require corrective prescription eyewear, like spectacles or contact lenses, might have faced a few problems about their choice of sunglasses Prescription sunglasses may then come in handy for those who wish to retain the same clarity of vision in the sun, which they enjoy indoors with their glasses or contact lenses on. They are available for many different lens prescriptions, including bifocal and progressive lens sunglasses. Polarized prescription sunglasses are also available, to reduce the glare from reflective surfaces like water, glass or snow.
- 13. Dangers of Cheap Sunglasses Beware of a price tag on sunglasses that looks unbelievably cheap! If it sounds too good to be true, it probably isn’t. Cheap sunglasses that lack a UV filter are in fact more dangerous to the eyes than not wearing sunglasses at all, since they cause the pupils to dilate, which invites more rays into the eyes. Before using a pair of sunglasses, always check with your optician about the level of UV protection it offers.
- 14. Thank You for your time Shroff Eye Hospital & Lasik Centre 222, S V Road, Near Suburbia Movie Theatre, Bandra West, Mumbai- 400050. Maharashtra. Shroff Eye Clinic Gobind Mahal, 8-B,N. Subhash Road Marine Drive, Mumbai- 400002. Maharashtra. 022 - 66921000 Visit our website below for more information Shroffeye.org Lasikindia.in Smilerelex.com 022 - 22814077