AMBLYOPIΑ TYPE AND MANAGEMENT TREATMENT.pptx

Amblyopia
Types
Classification
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1. AMBLYOPIΑ By shahziya

2. DEFINITION Also known as ‘Lazy eye’. Amblyopia is a condition with unilateral or bilateral decrease of visual functions, caused by form vision deprivation and/or abnormal binocular Interaction, that cannot be explained by a disorder of ocular media or visual pathways itself. In appropriate cases it is reversible by therapeutik measures. It is a condition caused by abnormal visual experience during early childhood the critical period of visual development.

3. Over the years a lot of work, expeimental as well as clinical has been done in the study of central visual pathways, which has moved some cobwebs but suspense still remains. The prevalence of amblyopia in general population can be estimated to be 2-2.5% from the various surveys conducted in selected populations. In pre-school and school children it has been reported to be 1.3 to 3.5%, in recruited soldiers it is 1-4% and in ophthalmic patients it is 4-5%.

4. Classification Strubismic amblyopia Anisometric amblyopia (unilateral or asymmetric) Anisohyperopic Anisomyopic Form Vision Deprivation amblyopia (unilateral or bineral) Stimulus deprivation amblyopia or asymmetric amblyopia (ex anopsia) due to ptosis (covering pupil), media opacities (cornea, lens or vitreous), unilateral occlusion or penalisation.

5. b. Ametropic amblyopia An uncorrected bilateral high refractive error. Hyperopia Myopia Astigmatism (meridional amblyopia) 4. Nystagmus related amblyopia 5. Organic amblyopia Sub-clinical macular damage Malorination of cones Cone deficiency syndrome

6. Strabismic amblyopia Amblyopia seen in those patients with unilateral constant squint who strongly favour one eye for fixation. Typical Features: Grating acuity is better than snellen's acuity Always unilateral More often in esotropes than exotropes Very rare in hypertropia (anomalous head posture) Do not occur in alternate strabismus.

7. Anisometropic amblyopia Amblyopia caused by a difference in refractive power between the eyes and may result from a difference of as little as 1.0 D sphere More common in anisohypermetropia than in those with anisomyopia. Strabismus is frequently associated with anisometropia and hence both strabismic amblyopia and anisometropic amblyopia can coexist. Meridional amblyopia In patients with uncorrected astigmatic refractive error due to selective visual deprivation at certain special orientaion. Even small amount of U/L astigmatism may cause amblyopia

8. Stimulus deprivation Amblyopia resulting from those conditions where in one eye is totally excluded from seeing early in life. Monocular congenital or traumatic cataract, complete ptosis, corneal opacity, prolonged patching of the normal eye for the treatment of amblyopia etc. Features : Most damaging and difficult to treat Amblyopic visual loss resulting from U/L deprivation is worser than that produced by B/L deprivation of similar degree. This is because, in U/L deprivation, interocular effects add to image degradation.

9. Nystagmus related amblyopia Nystagmus-related amblyopia is a type of amblyopia that occurs in individuals with nystagmus, a condition characterized by involuntary eye movements. The constant eye movements can blur vision and make it difficult for the brain to develop a clear and stable image. This can lead to amblyopia, where the brain suppresses the input from the weaker eye, resulting in poor vision in that eye. The mechanism behind nystagmus-related amblyopia is not fully understood, but it is thought to be related to the following factors:

10. Blurred vision: The constant eye movements can cause blurred vision, making it difficult for the brain to develop a clear image. Reduced visual input: The rapid eye movements can reduce the amount of visual information that reaches the brain, hindering the development of the visual system. Abnormal visual development: The constant eye movements can disrupt the normal development of the visual system, leading to amblyopia. .

11. Organic amblyopia Organic amblyopia is a type of amblyopia caused by an underlying medical condition affecting the eye or visual pathway It's not directly related to refractive errors, strabismus, or deprivation.

12. Sub-clinical macular damage Subclinical macular damage refers to damage to the macula, the central part of the retina responsible for sharp, detailed vision, that is not yet causing noticeable symptoms. This damage can be detected through specialized eye exams, but the individual may not experience any vision loss or visual disturbances Subclinical macular damage can be associated with amblyopia, but it's not a direct cause. Amblyopia is primarily caused by a lack of proper visual stimulation during early childhood, leading to the brain favoring one eye over the other. However, subclinical macular damage can contribute to amblyopia in a few ways:

13. Reduced visual input: If the macula is slightly damaged, it may reduce the amount of visual information reaching the brain, potentially contributing to the development of amblyopia. Abnormal visual development: Subclinical macular damage can disrupt the normal development of the visual system, making the brain more susceptible to amblyopia. Increased risk of amblyopia: Individuals with subclinical macular damage may be at a higher risk of developing amblyopia, especially if they have other risk factors, such as strabismus or refractive errors. It's important to note that subclinical macular damage is not always a cause of amblyopia. Many individuals with subclinical macular damage do not develop amblyopia. However, it's crucial to have regular eye. exams to detect any potential problems early on and address them appropriately.

14. Malorientation of cones Malorientation of cones refers to a condition where the cone cells in the retina, responsible for color vision, are not properly aligned. This misalignment can affect the way light is received and processed, leading to various visual disturbances, including: Reduced visual acuity: The misaligned cones may not be able to focus light properly, resulting in blurry vision. Color vision defects: The malorientation of cones can affect the ability to perceive certain colors accurately, leading to color blindness or color vision deficiency. Metamorphopsia: This refers to distorted vision, where straight lines appear wavy or curved.

15. While malorientation of cones can contribute to visual impairment, it's not directly linked to organic amblyopia. Organic amblyopia is caused by underlying medical conditions affecting the eye or visual pathway, not by the misalignment of cones. However, it's possible that malorientation of cones could be a contributing factor in some cases of organic amblyopia. For example, if the malorientation is severe enough to significantly reduce visual input, it could potentially contribute to the development of amblyopia. It's important to note that the relationship between malorientation of cones and organic amblyopia is complex and not fully understood. Further research is needed to clarify the connection between these two conditions.

16. Cone deficiency syndrome Cone deficiency syndrome is a rare genetic condition that affects the development of cone cells in the retina. This can lead to various visual impairments, including: Reduced color vision: Individuals with cone deficiency syndrome may have difficulty distinguishing certain colors, leading to color blindness or color vision deficiency. Reduced visual acuity: The lack of properly functioning cone cells can affect the sharpness of vision, resulting in blurry vision. Photophobia: Sensitivity to light is common in individuals with cone deficiency syndrome.

17. While cone deficiency syndrome can affect visual development, it's not directly linked to organic amblyopia. Organic amblyopia is caused by underlying medical conditions affecting the eye or visual pathway, not by a genetic deficiency in cone cells. However, it's possible that cone deficiency syndrome could contribute to the development of amblyopia in some cases. For example, if the cone deficiency is severe enough to significantly reduce visual input, it could potentially contribute to the development of amblyopia. It's important to note that the relationship between cone deficiency syndrome and organic amblyopia is complex and not fully understood. Further research is needed to clarify the connection between these two conditions.

18. Medical Care The clinician must first rule out an organic cause and treat any obstacle to vision (eg. cataract, occlusion of the eye from other etiologies). Cataracts should be removed in the first 2 months of life, and aphakic or refractive correction must occur quickly so that occlusion therapy can be initiated. Although the success rate for treatment of amblyopia is likely to be higher in younger patients, older patients who have yet to receive therapy may still benefit.

19. Treatment of anisometropia and refractive errors must occur next, The amblyopic eye must have the most accurate optical correction possible. This should occur prior to any occlusion therapy because vision may improve with spectacles alone. This improvement is frequently seen in patients with unilateral refractive amblyopia.

20. Full cycloplegic refraction should be given to patients with accommodative esotropia and amblyopia. In other patients, a prescription less than the full plus measurement that was refracted may be prescribed with the decrease in plus kept symmetric between the two eyes. Because accommodative amplitude is believed to be decreased in amblyopic eyes, one needs to be cautious about cutting back too much on the amount of plus. Refractive correction alone has been shown to improve amblyopia in up to one-fourth of patients in a nationwide trial, Patients with bilateral refractive amblyopia do well with spectacle correction alone, with most children aged 3-10 years achieving 20/25 or better within a year.

21. Occlusion therapy The next step after refractive correction is forcing the use of the amblyopic eye. Occlusion therapy has been the mainstay of treatment since the 18th century. The following are general guidelines for occlusion therapy: Patching may be full-time or part-time. Standard teaching has been that children need to be observed at intervals of 1 week per year of age, if undergoing full- time occlusion to avoid occlusion amblyopia in the sound eye. The Amblyopia Treatment Studies (ATS) have helped to provide new information on the effect of various amounts of patching.

22. Always consider lack of compliance in a child in whom visual acuity is not improving. Compliance is difficult to measure but is an important factor in determining the success of this therapy. In addition to adhesive patches, opaque contact lenses, occluders mounted on spectacles, and adhesive tape on glasses have been used. In all of these methods, it should be ensured that the sound eye is occluded well to avoid peeking. Establishing the fact that the vision of the better eye has been degraded sufficiently with the chosen therapy is important.

23. The Amblyopia Treatment Studies have also found that about one fourth of children with amblyopia who were successfully treated experience a recurrence within the first year after discontinuation of treatment. Data from these studies suggest that patients treated with 6 or more hours a day of patching have a greater risk of recurrence when patching is stopped abruptly rather than when it is reduced to 2 hours a day prior to cessation of patching. There is some evidence that having children wear an eye patch for 6 hours daily rather than 2 hours can yield greater improvement in visual acuity at 10 weeks.

24. The significantly greater improvement in visual acuity noted with the more intense patching protocol suggests that this strategy is worth considering in children with residual amblyopia. The results have the following implications:If there is stable residual amblyopia after 12 weeks of 2-hour patching, an increase to 6-hour patching may bring about further improvement. If the goal is to achieve the best result in the shortest amount of time, it may be worthwhile to bypass 2-hour patching and start with 6-hour patching instead.