Amblyopia in Pakistani children age 3 to 14 years.
Amblyopia is classically defined as a reduction in corrected visual acuity (VA) in absence of visible organic abnormalities and is due to misdirected, blurred, or absent retinal images during development of visual system. It is the most frequent cause of monocular visual impairment in both young and adults.
Cause of Amblyopia
Strabismic amblyopia is the most common form of amblyopia which develops in consistently deviating eye of the child with ocular misalignment. Constant or alternate tropias (typically esodeviations) are most likely to cause significant amblyopia.
Anisometropic amblyopia is second in frequency to strabismic amblyopia. Anisometropic amblyopia develops when refractive error in two eyes causes image on one retina to be chronically defocused. Relatively mild degrees of hyperopic or astigmatic anisometropia (1-2D) can induce amblyopia.
High Refractive Error
Mild myopic anisometropia (less than -3D) usually does not cause amblyopia but unilateral high myopia (-6D) often results in severe amblyopic visual loss. Isoametropic amblyopia is a bilateral reduction in visual acuity that is usually relatively mild, results from large approximately equal uncorrected refractive errors in both eyes of a young child. Hyperopia exceeding about +5D induces bilateral amblyopia.
Stimulus deprivation amblyopia is usually caused by congenital or early acquired media opacities. Stimulus deprivation amblyopia is least common but most damaging and difficult to treat.
High Astigmatism or Combination of Two or more Etiologies
Combined amblyopia includes patients with either heterotropia at near or distance along with anisometropia.
Treatment of Amblyopia
atropine in case of sensory deprivation amblyopia
Similarly in strabismic amblyopia once the visual acuity improves by amblyopia therapy surgery is performed to correct the ocular misalignment.
Result of Studies
Two hundred patients were choosen
Male patients 126 (63%)
Female patients 74 (37%)
Age Group 4-9 years 114 (57%)
Age Group 10-14 years (43%)
Strabismic Amblyopia 110 (55%) ---------- 110 = 83 (75%) esotropes + 27 (25%) exotropes
Anisometropic Amblyopia 42 (21%) = Myopes 16 (38%) + Hypermetropes 25 (60%) + Astigmatism 1 (2%)
Combined Mechanism Amblyopia 32 (16%) = Hypermetropia 27 (84%) + 4 (12.5%) Myopes + Astigmatism 1 (3.5%)
Ammetropia 12 (6%) = Hypermetropia 8 (66%) + Myopia 4 (36%)
Stimulus Deprivation 4 (2%) = Ptosis 1 (25%) + Congenital cataract 2 (50%) + Corneal scar 1 (25%)
Amblyopia = 72 (36%) mild amblyopia + 102 (51%) Moderate amblyopia + 26 (13%) Severe amblyopia
Fixation . Central 112 (56%) + Eccentiric 72 (36%) + No fixation 16 (8%)
Binocularaty = not assessed 16 (8%) + Present 38 (19%) + Absent 146 (36%)
Treatment = Success 155 (77.5%) + no success 45 (22.2%)