The axial length/disc area ratio in anisometropic hyperopic amblyopia: a hypothesis for decreased unilateral vision associated with hyperopic anisometropia.
OBJECTIVE
Hyperopic anisometropia is a risk factor for amblyopia. Disc areas and axial lengths are reduced in amblyopic eyes. This study's aim was to investigate the differences in the relative size of the optic disc in 5 groups of eyes: (1) normal right eyes; (2) smaller eyes of nonamblyopic, anisometropic, bilateral hyperopes; (3) larger eyes of nonamblyopic, anisometropic, bilateral hyperopes; (4) fellow (nonamblyopic) eyes of eyes of amblyopic, anisometropic, bilateral hyperopes; and (5) amblyopic eyes of bilateral hyperopic anisometropes. To determine the relative size of the discs, the relationships of axial length to disc area in the above groups were evaluated.


METHODS
Case-control study.


METHODS
Nine hundred twenty-seven records from the author's private practice, which included axial length measurements and optic disc photographs or digital images, were analyzed to form the 5 groups above.


METHODS
Disc areas were measured using objective techniques developed by Bengtsson and Krakau. Axial lengths were determined by ultrasound biometry or with a Zeiss IOL Master.


METHODS
Optic disc areas, corrected for magnification, axial lengths, and a derived ratio, axial length/disc area (AXL/DA).


RESULTS
The AXL/DA for the amblyopic eyes (group 5) was significantly greater than that of all of the other groups, indicating that amblyopic eyes have discs that are both absolutely smaller and, when adjusted for eyes' size, relatively smaller than those of nonamblyopic eyes.


CONCLUSIONS
The relatively small size of the discs of amblyopic eyes points to an organic as opposed to a functional amblyopia in these patients.
Lempert
Philip
P
College of Veterinary Medicine, Cornell University, Ithaca, New York 14850, USA. eyechartplus@aol.com
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000550:Amblyopia / Q000150:complications*; D015858:Anisometropia / Q000150:complications*; D001837:Body Weights and Measures; D002648:Child; D002675:Child, Preschool; D005123:Eye / Q000473:pathology*; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000150:complications*; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000473:pathology*; D010684:Philosophy; D012189:Retrospective Studies; D014786:Vision Disorders / Q000209:etiology*