Astigmatism.pptx
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Astigmatism is a refractive condition where the eye's refractive power varies in different meridians, causing blurred vision. It occurs when the cornea or lens is irregularly curved or positioned. Common causes are corneal abnormalities, lenticular conditions, or retinal placement issues. Symptoms include blurred distance and near vision. Diagnosis involves visual acuity tests, autorefraction, keratometry, and retinoscopy. Treatment options are spectacle lenses, toric contact lenses, and refractive surgery such as PRK or LASIK.
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DIRECT DOWNLOAD LINK ❤❤https://healthkura.com/lazy-eye-amblyopia/❤❤
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Summary
Amblyopia occurs due to abnormal visual experience early in life
Proper optical correction alone is necessary for short period of time (6-8 weeks)
before initiation of other therapy
Part time occlusion of better eye is mainstay of treatment since 18th century to till
now
For severe and moderate amblyopia, 6 hrs and 2 hrs of patching is advised
respectively
Atropine is also used in children with poor compliance
Trial of patching can be given in patients as old as 17 yrs
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amblyopia treatment beyond the critical period of visual development
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promising result to replace the patching therapy till date
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1. Subjective refraction testing involves determining the best corrective lenses for a patient through their feedback, and aims for a visual acuity of 6/5.
2. Techniques include monocular and binocular testing, refinement of the cylinder and sphere powers, and verification of near vision after age 40.
3. Advantages are that it can be done without special equipment, but disadvantages include variable results due to accommodation and lack of patient cooperation in some cases.
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Treating with prism
Strabismus, or crossed eyes, occurs when the eyes do not look at the same place at the same time. It is usually caused by poor eye muscle control or farsightedness. Strabismus can be inward, outward, upward, or downward turning. Fresnel prisms are special lenses that use prism power to alter light and reduce eye turning. Prisms are also used to treat conditions like anisometropia, cranial nerve palsies, enhancing communication for patients with no vision in one eye, homonymous hemianopia, nystagmus with head turn, and convergence insufficiency. Prisms bring images into the visual field or keep the eyes in a
Anomalies of accomodation
Accommodation anomalies can occur due to various causes and present with different symptoms. Assessment involves dynamic retinoscopy and measuring accommodation amplitudes. Accommodative fatigue can result from overuse and be treated by correcting refractive errors and discussing visual hygiene. Presbyopia is age-related and treated with near vision correction. Other failures of accommodation include insufficiency, paralysis, spasm, and sustained accommodation, each with different etiologies, signs, and treatments.
Design's of pal's
This document discusses different designs of progressive additional lenses (PALs). It describes hard and soft, symmetrical and asymmetrical, mono and multi designs. Conventional PALs add power on the front surface while internal PALs add power to the back surface. Digital PALs and freeform technology allow for smoother progression of power. Specialty PALs include short corridor and near variable focus lenses tailored for specific tasks. The document provides details on characteristics and advantages and disadvantages of each PAL design.
Contrast sensitivity
Contrast sensitivity refers to the ability to see objects that have low contrasts or do not stand out clearly from their backgrounds. It is measured using charts with different spatial frequencies and contrast levels to determine the minimum contrast needed to see a target. Contrast sensitivity is affected by many eye diseases and conditions more subtly than visual acuity and can provide early detection of problems. It is tested using various charts like Pelli-Robson, Cambridge Low Contrast Gratings, and Functional Acuity Contrast Testing (FACT) that evaluate contrast sensitivity levels at different spatial frequencies.
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1. Intermittent exotropia is thought to be caused by an imbalance between convergence and divergence muscles. It typically begins as exophoria in infancy and progresses to intermittent exotropia.
2. Examination includes measuring the deviation at distance and near with and without lenses to classify the type. Non-surgical treatment aims to improve vergence control through patching, lenses, and orthoptics.
3. Surgical treatment is indicated for deviations over 20 prism diopters, worsening control, or failure of conservative therapy.
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Brown's syndrome is a condition where there is limited elevation of the eye in adduction due to impaired movement of the superior oblique tendon through the trochlea. It can be congenital or acquired. Congenital cases are usually idiopathic while acquired cases result from damage to the trochlea or tendon, or inflammation. Symptoms include limited elevation in adduction, a positive forced duction test, and occasionally downshoot in adduction or anomalous head posture. Treatment depends on whether the case is congenital or acquired, with congenital cases often not requiring treatment and acquired cases potentially benefiting from steroids and treatment of the underlying cause.
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This document discusses congenital infantile esotropia. It defines esotropia as eyes turning inward and provides background on types. Congenital infantile esotropia is characterized by a large-angle esotropia present before 6 months of age. It may be associated with cerebral palsy or low birth weight. Treatment involves correcting refractive errors, amblyopia therapy, and bilateral medial rectus recession surgery between 6 months to 2 years of age. Post-surgical outcomes include orthophoria, small residual deviations managed with observation, or large residual deviations requiring repeat surgery.
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Binocular single vision refers to simultaneous vision with two eyes that occurs when an individual fixates on an object. There are three grades of binocular vision: simultaneous perception, fusion, and stereopsis. Fusion is the ability to see a composite picture from two similar images, while stereopsis provides the impression of depth by superimposing images from slightly different angles. Tests for binocular vision include those for simultaneous perception, fusion, and stereopsis using instruments like the synaptophore. Binocular vision develops through infancy and childhood as the visual axes become coordinated to direct each fovea at the object of regard.
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1) The standard 4-map composite report, keratoconus map, Holladay report, and Belin/Ambrosio Enhanced Ectasia Display.
2) Key features to examine on each map include anterior and posterior elevation maps, pachymetry maps, curvature maps, and indices values.
3) The Belin/Ambrosio Enhanced Ectasia Display aims to improve sensitivity by calculating an "enhanced" best fit sphere reference surface that excludes the thinnest corneal region, highlighting differences between normal and ectatic corneas.
Optical aberrations
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Anterior ischemic optic neuropathy
This document provides information on anterior ischemic optic neuropathy (AION), which is the most common cause of acute optic neuropathy in older age groups. It can be divided into two types: arteritic AION, which is due to giant cell arteritis; and non-arteritic AION, which makes up most cases. Both types present with sudden painless vision loss and optic disc swelling. Arteritic AION carries a worse prognosis and requires high-dose steroid treatment to prevent loss of vision in the fellow eye. Non-arteritic AION has a variable course but generally a poor rate of recovery without any proven effective treatments.
Duane retraction syndrome
This document discusses Duane retraction syndrome, an ocular motility disorder characterized by defective horizontal eye movement and narrowing of the eyelid when the eye adducts. It is usually unilateral and sporadic, though some familial cases are due to mutations in the CHN1 gene. There are four types described based on limitations of adduction and abduction. Duane syndrome can occur with other syndromes and limb abnormalities. Clinical features and differential diagnosis are provided. Surgical treatment depends on the type of strabismus and may include recession or resection of extraocular muscles.
Current Trend in Management of Amblyopia (Amblyopia Therapy)/ Amblyopia Treat...
DIRECT DOWNLOAD LINK ❤❤https://healthkura.com/lazy-eye-amblyopia/❤❤
Dear viewers, to download this presentation visit___ https://healthkura.com/lazy-eye-amblyopia/
Current Trend in Management of Amblyopia. Latest as well as old methods of amblyopia management which include active and passive therapies. Amblyopia Therapy/ Amblyopia Treatment
What would be the perfect amblyopia therapy?
Effective
Good compliance
Acceptable to pts. and parent
Quick
Safe
Easy to administer
Cost effective
Well maintained
..............
Summary
Amblyopia occurs due to abnormal visual experience early in life
Proper optical correction alone is necessary for short period of time (6-8 weeks)
before initiation of other therapy
Part time occlusion of better eye is mainstay of treatment since 18th century to till
now
For severe and moderate amblyopia, 6 hrs and 2 hrs of patching is advised
respectively
Atropine is also used in children with poor compliance
Trial of patching can be given in patients as old as 17 yrs
Perceptual learning and pharmacological manipulation have shown areas of
amblyopia treatment beyond the critical period of visual development
Binocular stimulation, software based treatments and other methods do not have
promising result to replace the patching therapy till date
Most of the active therapy methods have good results when used together with
patching therapy
Subjective refraction
This document provides information on subjective refraction testing including the steps, advantages, disadvantages, and techniques used. The key points are:
1. Subjective refraction testing involves determining the best corrective lenses for a patient through their feedback, and aims for a visual acuity of 6/5.
2. Techniques include monocular and binocular testing, refinement of the cylinder and sphere powers, and verification of near vision after age 40.
3. Advantages are that it can be done without special equipment, but disadvantages include variable results due to accommodation and lack of patient cooperation in some cases.
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Optics of human eye & refractive errors
The document discusses the anatomy and optics of the human eye. It describes the main components of the eye, including the cornea, iris, lens, retina, and their functions. It also covers topics like emmetropia, refractive errors including myopia and hyperopia, their types and clinical features. Schematic and reduced eye models are introduced to conceptualize the optical properties of the eye.
OPTICS OF HUMAN EYE & REFRACTIVE ERRORS
The document discusses the anatomy and optics of the human eye. It describes the main components of the eye, including the cornea, iris, lens, retina, and their functions. It also covers topics like emmetropia, refractive errors including myopia and hyperopia, their causes and treatments. Schematic and reduced eye models are introduced to conceptualize the optical properties of the eye.
Refractive error
Refractive errors occur when the eye does not bend light correctly, causing blurred vision. The main types are myopia, hyperopia, presbyopia, and astigmatism. Myopia causes distant vision to be blurred as light focuses in front of the retina. Hyperopia is the opposite, with near vision blurred from light focusing behind the retina. Presbyopia is age-related blurred near vision. Astigmatism results in distorted vision from an irregularly curved cornea. Diagnosis involves visual acuity and refraction tests. Treatment options include corrective lenses, contact lenses, and various refractive surgeries to reshape the cornea such as LASIK and PRK.
Error of Refraction
This document provides an overview of refractive errors and their correction presented by Prof. Vijayreddy Vandali. It defines key terms like emmetropia, diopter, and accommodation. It describes different types of refractive errors - hyperopia, myopia, astigmatism, presbyopia and anisometropia. For each error, it discusses causes, signs and symptoms, and methods of correction using lenses, contact lenses or surgery. Surgical procedures discussed for correction include LASIK, PRK, radial keratotomy, INTACS and phakic intraocular lens implants. The document aims to educate about different refractive errors, their diagnosis and management.
Myopia
This document discusses myopia (nearsightedness), including its optics, etiological classifications, clinical varieties, and treatment options. Myopia occurs when light rays focus in front of the retina rather than directly on it. It can be axial, curvatural, or positional. Treatment includes optical correction with glasses or contacts, as well as refractive surgeries like LASIK, PRK, clear lens extraction, phakic IOL implantation, intracorneal ring segments, and orthokeratology. More advanced techniques like LASIK and ICLs can correct higher degrees of myopia over -12 diopters.
Sturms conoid
Astigmatism is an optical condition where the cornea and lens have different refractive powers in different meridians, resulting in two focal points instead of one. The distance between focal points is called the Sturm's conoid interval. Astigmatism can be caused by abnormalities in the cornea or lens. It can be regular, where the meridians are perpendicular, or irregular. Symptoms include blurry vision, asthenopia, and headaches. Treatment options include glasses, contact lenses, and refractive surgery like LASIK or LASEK.
Sturms conoid
Astigmatism is an optical condition where the cornea and lens have different refractive powers in different meridians, resulting in two focal points instead of one. The distance between focal points is called the Sturm's conoid interval. Astigmatism can be caused by abnormalities in the cornea or lens. It can be regular, where the meridians are perpendicular, or irregular. Symptoms include blurry vision, asthenopia, and headaches. Treatment options include glasses, contact lenses, and refractive surgery like LASIK or LASEK.
astigmatism sturms cnoid
Astigmatism is an optical condition where the cornea and lens have different refractive powers in different meridians, resulting in two focal points instead of one. The distance between focal points is called the Sturm's conoid interval. Astigmatism can be caused by abnormalities in the cornea or lens. It can be regular, where the meridians are perpendicular, or irregular. Symptoms include blurry vision, asthenopia, and headaches. Treatment options include glasses, contact lenses, and refractive surgery like LASIK or LASEK.
Astigmatism
Astigmatism is refractive error of the eye in which there is difference in degree of refraction in different meridians
myopia-141210010058-conversion-gate01.pdf
Dr. Om Patel presented on myopia (nearsightedness). There are several types and causes of myopia, including axial myopia caused by an elongated eyeball, curvatural myopia from increased corneal or lens curvature, and pathological myopia associated with degenerative changes. Treatment options discussed included optical correction with glasses or contacts, as well as surgical procedures like LASIK, PRK, and phakic intraocular lenses for high myopia. The goal of treatment is to slow progression and provide clear vision.
optics.Dr.Mutaz.ppt
This document provides an overview of optics and refraction for 5th year medical students. It defines key terms related to light, refraction, the eye, and refractive errors. It describes how the eye focuses light onto the retina using the cornea and lens. Refractive errors like myopia, hyperopia, and astigmatism occur when light is not correctly focused on the retina. Methods for correcting refractive errors include glasses, contact lenses, and refractive surgery procedures.
Refractive Errors
This document discusses the anatomy and physiology of the eye and various eye conditions. It describes the three main parts of the eye: eyeball, orbit, and accessory structures. It then discusses the layers of the eye and specific structures like the lens. Various refractive errors are defined and described like emmetropia, ametropia, myopia, hypermetropia, and astigmatism. Causes, types, symptoms and treatments are provided for each condition. Assessment methods for eye problems are also listed.
11. Refractive errors.pptx
This document discusses refractive errors of the eye. It defines the three main types as myopia, hypermetropia, and astigmatism. Myopia occurs when light focuses in front of the retina. Hypermetropia is when light focuses behind the retina. Astigmatism is when light does not focus to a single point on the retina. Each type is then further described in terms of causes, presentations, complications, and management approaches which typically involve corrective lenses, refractive surgery, or lens extraction and implantation.
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Astigmatism.pptx
- 1. Dr. Atul Kumar Anand Senior Resident AIIMS Patna
- 3. A refractive condition in which a variation of power exists in the different meridians of the eye.
- 4. Astigmatism by definition is a condition where the parallel beam of light rays incident on the cornea after refraction are not focused to form a point image near or on the retina
- 5. Irregular curvature or RI in the anterior surface of cornea Irregular curvature or RI and also the position of lens/IOL The refracting power is not uniform in all meridians of both lens or cornea
- 6. Based on axis of the principal meridians Regular astigmatism – principal meridians are perpendicular • With-the-rule astigmatism • Against-the-rule astigmatism • Oblique astigmatism Irregular astigmatism - principal meridians are not perpendicular
- 7. Correctable by cylindrical lenses Etiology : 1. Corneal - abnormalities of curvature [common] 2. Lenticular is rare. It may be: i. Curvatural - abnormalities of curvature of lens as seen in lenticonus. ii. Positional - tilting or oblique placement of lens , subluxation. 3. Retinal - oblique placement of macula [rare]
- 8. Based on focus of the principal meridians Simple astigmatism • Simple hyperopic astigmatism • Simple myopic astigmatism Compound astigmatism • Compound hyperopic astigmatism • Compound myopic astigmatism Mixed astigmatism
- 11. •Distorted vision at distance and near •Letter confusion •Asthenopia or ocular fatigue •Headaches •Squinting
- 12. • Symptoms : Blurring of vision Asthenopic symptoms Tilting of head Squinting
- 13. Visual acuity tests – distance and near Autorefraction Keratometry Retinoscopy Monocular subjective refraction
- 14. Spectacles Cylindrical lenses and spherocylindrical lenses in spectacles Contact lens Toric soft contact lenses rigid gas permeable contact lenses Refractive surgery Photorefractive keratectomy (PRK) Laser in-situ keratomileusis (LASIK)
- 15. Astigmatic fan Jackson’s cross cylinder Stenopic slit
- 16. • Etiology : Corneal -[ Scars , Keratoconus flap complications, marginal degenration ] Lenticular -[Cataract maturation] Retinal-[scarring of macula, tumours of retina,choroid]
- 17. Symptoms : Defective vision Distorsion of objects Polyopia Investigations: - Placido's disc test reveals distorted circles - Computerized corneal topography
- 19. Optical treatment : - RGP contact lenses -Hybrid contact lenses -Scleral lenses Surgical treatment: - penetrating keratoplasty
- 20. The amount of astigmatism that still remains after correction of a refractive error.
- 21. Difference in refractive power between 2 eyes refractive correction often leads to different image sizes on the 2 retinas( aniseikonia) aniseikonia depend on degree of refractive anomaly and type of correction
- 22. Glasses : magnified or minified 2% per 1 D Contact lens : change less than glasses Tolerate aniseikonia ~ 5-8% Treatment • anisometropia > 4 D-->contact lens • unilateral aphakia-->contact lens or intraocular lens