Amblyopia 2

amblyopia opthalmology for mbbs students

1. By AMEERHAMZA S B 6 th term MBBS Shimoga Institute of Medical Sciences Shimoga AMBLYOPIA

2. How we see? We learn to see, like walking or talking Learning to see is a slow process At birth – vision is noisy, can not distinguish targets Object tracking starts around 3 month old Hand-eye-body coordination starts after 3 month old Depth perception appears after 5 month old Vision is well developed by two years old

3. Definition: It refers to a partial reversible loss of vision in one or both eyes, for which no cause can be found by physical examination of eye(absence of any organic disease).

4. Pathogenesis Amblyopia is an  eye  condition when the nerves that connect one of the eyes to the brain do not develop correctly during childhood. As a result, the person sends blurry or wrong images to their brain, which results in the brain ignoring the information and favoring the other eye. Patients are seen using one eye more or may have problems with depth perception. 

5. TYPES

6. Strabismic amblyopia Two eye moves in two direction Brain cannot combine image from two eye into one Double vision Brain starts to ignore image from one eye Causes unilateral amblyopia

7. Stimulus deprivation amblyopia Congenital or traumatic cataract or corneal haziness Occlude lights to reach the retina No or distorted image formed on retina No visual learning happens Both unilateral or bilateral amblyopia can occur

8. Anisometropic amblyopia Different focusing power in two eye One eye gives clearer image than other Brain starts to ignore the blurrier image Causes unilateral amblyopia

9. Isoametroipc amblyoipa Is bilateral amblyopia occuring in children with bilateral uncorrected high refractive error Occurs in children eith uncorrected astigmatic refractive error Meridional amblyoipa

10. Clinical features Visual acuity is decreased Crowding phenomenon : visual acuity is less when tested with multiple letter charts ( eg.snellen’s chart)than single letter charts ( eg.optotype ).

11. Treatment Younger the child , better is the prognosis. Works best when child is under 3yrs of age. Occlusion therapy : occlusion normal eye to force use of amblyopic eye

12. Before that procedure it should be ensured that If any cataract…. is corrected. If any refractive error…is corrected. Upto 2 yrs it should be done in 2:1 i.e. 2 days occlusion in normal eye and one day in amblyopic eye. At the age of 3… 3:1 At the age of 4….4:1 At the age of 5….5:1…..until the visual acuity develops fully

13. Penalization i.e. blurring of vision of normal eye either by using Atropine ( Atropine penalization ) or Over plus lenses in spectacles ( optical penalization )

14. Computerized vision therapy It works on the form of operant conditioning(a form of psychological treatment) Computerized Home Vision Therapy (CHTV) can prescribed as an alternative to occlusion therapy.

15. Other treatments

16. Refernces Comprehensive Opthalmology by A.K.Khurana ,6 th Edition.