Anomalous Vascular Patterns of the Optic Disc in Amblyopia.

PURPOSE: To evaluate the presence of anomalies of the optic disc vascular patterns in subjects with amblyopia. DESIGN: Case controlled study. The outcome measure is temporal deviation of central retinal vessels and / or vascular pattern asymmetry. METHODS: A total of 342 hyperopic amblyopic patients were evaluated. An additional 88 subjects with equal visual acuity with strabismus, and 108 subjects with equal visual acuity and anisometropia were evaluated. RESULTS: In this study, more than 50% of amblyopic patients had optic disc deformities. Sixty-five percent of subjects with amblyopia, orthophoria, and anisometropia exceeding 1.5 D had these anomalies compared with less than 7% of the groups without amblyopia or strabismus. CONCLUSIONS: These disc anomalies may be associated with disorganization of optic nerve axons. This finding indicates the possibility of a peripheral cause for impaired vision and could provide an explanation for the variability in visual defects associated with amblyopia. Optic nerve imaging should be incorporated into clinical protocols for amblyopia research.

Optic disc area and retinal area in amblyopia.

PURPOSE: To compare retinal area to optic disc rim area ratios of hyperopic normal, strabismic eyes with equal acuity, amblyopic, and fellow eyes. METHODS: Neuroretinal rim areas of 293 amblyopic and fellow eyes, and 77 non-amblyopic hyperopic right eyes, and 84 non-amblyopic strabismic right eyes were measured by magnification corrected retinal photography and planimetry. Retinal area estimates were based on axial lengths. INCLUSION CRITERIA: All subjects had bilateral hyperopia. Patients with glaucoma or known optic nerve atrophy were excluded. The normal and strabismic groups had equal visual acuity in each eye better than 20/40. The amblyopic group had acuity worse than 20/40 in one eye uncorrectable with lenses and without gross anatomic defects. RESULTS: The amblyopic group included 137 with strabismus and 89 with anisometropia exceeding 1.5 diopters. There were highly significant differences between the ratio of retinal area to optic disc rim area of the amblyopic and of normal eyes (unpaired t-test, p = 8.6 x 10(-6)), the amblyopic and strabismic right eyes (unpaired t-test, p = 4.22 x 10(-8)) as well between the fellow and amblyopic eyes (paired t-test, p = 2.13 x 10(-5)). The difference between the normal and strabismic eyes without amblyopia was not significant (p = 0.82). There was a 20 percent increase in the retinal receptor areas of hyperopic amblyopic eyes as compared to hyperopic eyes without amblyopia despite reduced retinal areas in the amblyopic eyes. Dysplastic and/or asymmetric optic discs were present in 163 of 293 (56 percent) amblyopic patients, 47 of 84 (56 percent) strabismic, and 10 of 77 (13 percent) normal patients. CONCLUSIONS: The increase in the receptor area may be an explanation for diminished acuity and impaired visual function in amblyopic eyes.

Retinal area and optic disc rim area in amblyopic, fellow, and normal hyperopic eyes: a hypothesis for decreased acuity in amblyopia.

PURPOSE: Defects in visual functions in amblyopic eyes may have a neuroretinal explanation. The retinal area to optic disc rim area ratios of hyperopic normal, amblyopic, and fellow eyes were evaluated. DESIGN: Case-controlled study. PARTICIPANTS: A total of 293 patients with amblyopia and bilateral hyperopia and 77 non-amblyopic bilaterally hyperopic patients without strabismus. METHODS: Disc areas were measured using magnification correction formulas developed by Bengtsson and Krakau. Axial lengths were determined by ultrasound biometry or laser interferometry with a Zeiss AOL Master (Carl Zeiss Co., Oberkochen, Germany). The visual area of the retina was calculated using axial length measurements. MAIN OUTCOME MEASURES: Optic disc rim areas, corrected for magnification, retinal areas, and a derived ratio, retinal area/disc rim area (RetA/DRimA). RESULTS: The RetA/DRimA for the amblyopic eyes was significantly greater than that of the fellow and normal eyes, indicating that amblyopic eyes have larger retinal receptor areas than fellow or normal eyes. The RetA/DRimA of the fellow eyes was smaller than for the amblyopic but larger than that of the normal eyes. These differences were due to smaller optic disc rim areas in the amblyopic and fellow eyes. CONCLUSIONS: Amblyopic and their fellow eyes, when compared with normal eyes, have reduced innervations of comparable retinal areas. These differences can be attributed to a paucity of nerve fibers, as indicated by the smaller neuroretinal rim areas. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any materials discussed in this article.