Table 2.
Breakdown of the causes of gold standard eye examination failure (N = 65)a
| Classification | Description | Number (%) |
|---|---|---|
| Reduced VA due to uncorrected refractive error | VA improved to normal for age with refractive correction in place; no strabismus or media opacity | N = 31 (48) |
| Media opacity | VA remained subnormal for age with refractive correction in place and refractive error (applying published criteria15) or strabismus not present, but media opacity diagnosed | N = 0 (0) |
| Unilateral amblyopia | VA remained subnormal for age with refractive correction in place, with interocular VA difference of ≥3 lines4 and refractive error and/or manifest strabismus present. | N = 7 (11) |
| Amblyogenic refractive error defined according to previously published criteria15: | ||
| • ≥1.00 D SE anisohyperopia | ||
| • ≥3.00 D SE anisomyopia | ||
| • ≥1.50 D anisoastigmatism | ||
| Bilateral amblyopia | VA remained subnormal for age in both eyes with refractive correction in place and refractive error in both eyes was either: | N = 8 (12) |
| • ≥ +4.00 D SE | ||
| • ≥ +2.00 D cylinder | ||
| • ≥ −6.00 D SE16 | ||
| Refractive error alone (normal VA) | Refractive error failed by gold standard thresholds (Table 1), but uncorrected VA was normal for age. | N = 8 (12) |
| Unexplained reduced VA | VA remained subnormal for age with refractive correction in place and refractive error (applying published criteria15); manifest strabismus or media opacity not present | N = 10 (15) |
| Ocular misalignment | Manifest strabismus >8 PD in primary position | N = 1 (2) |
D, diopters; PD, prism diopters; SE, spherical equivalent; VA, visual acuity.
a
Where there was more than one reason for failing the gold standard eye examination, cause of failure was classified hierarchically as follows: (1) uncorrected refractive error; (2) media opacity; (3) unilateral amblyopia; (4) bilateral amblyopia; (5) refractive error alone; (6) Unexplained reduced visual acuity. Patients were classified in the manifest strabismus category if a tropia >8 PD was present, but VA was normal and refractive error did not meet gold standard failure criteria.