Grating visual acuity results in the early treatment for retinopathy of prematurity study

Abstract

Objective: To compare grating (resolution) visual acuity at 6 years of age in eyes that received early treatment (ET) for high-risk prethreshold retinopathy of prematurity (ROP) with that in eyes that underwent conventional management (CM).

Methods: In a randomized clinical trial, infants with bilateral, high-risk prethreshold ROP (n = 317) had one eye undergo ET and the other eye undergo CM, with treatment only if ROP progressed to threshold severity. For asymmetric cases (n = 84), the high-risk prethreshold eye was randomized to ET or CM.

Main outcome measure: Grating visual acuity measured at 6 years of age by masked testers using Teller acuity cards.

Results: Monocular grating acuity results were obtained from 317 of 370 surviving children (85.6%). Analysis of grating acuity results for all study participants with high-risk prethreshold ROP showed no statistically significant overall benefit of ET (18.1% vs 22.8% unfavorable outcomes; P = .08). When the 6-year grating acuity results were analyzed according to a clinical algorithm (high-risk types 1 and 2 prethreshold ROP), a benefit was seen in type 1 eyes (16.4% vs 25.2%; P = .004) undergoing ET, but not in type 2 eyes (21.3% vs 15.9%; P = .29).

Conclusion: Early treatment of eyes with type 1 ROP improves grating acuity outcomes, but ET for eyes with type 2 ROP does not. APPLICATION TO CLINICAL MEDICINE: Type 1 eyes should be treated early; however, based on acuity results at 6 years of age, type 2 eyes should be cautiously monitored for progression to type 1 ROP. Trial Registration clinicaltrials.gov Identifier: NCT00027222.

Figure 1

Algorithm (flow chart) for randomized infants. *Incomplete data was due to failure to cooperate for monocular testing or failure to have had amblyopia therapy prescribed

Figure 2

Distribution of grating acuity outcomes for randomized eyes by treatment assignment. Normal = ≥ 13 cycles/degree; Below Normal = <13 cycles/degree to ≥ 6.4 cycles/degree; Poor = measurable acuity <6.4 cycles/degree; Blind/Low Vision = can detect only the 2.2-cm-wide stripes on the Low Vision Teller acuity card at any distance and at any location in the visual field, light percepti on only, or no light perception. Visual acuities in the Poor and Blind/Low Vision categories were classified as unfavorable outcomes.

Figure 3

Distribution of grating acuity outcomes for randomized eyes with Type 1(Figure 3A) and Type 2 (Figure 3B) ROP by treatment assignments (early treatment (ET) or conventional management (CM)). Normal = ≥ 13 cycles/degree; Below Normal = <13 cycles/degree to ≥ 6.4 cycles/degree; Poor = measurable acuity <6.4 cycles/degree; Blind/Low Vision = can detect only the 2.2-cm-wide stripes on the Low Vision Teller acuity card at any distance and at any location in the visual field, light perception only, or no light perception. Visual acuities in the Poor and Blind/Low Vision categories were classified as unfavorable outcomes.

Figure 3

Distribution of grating acuity outcomes for randomized eyes with Type 1(Figure 3A) and Type 2 (Figure 3B) ROP by treatment assignments (early treatment (ET) or conventional management (CM)). Normal = ≥ 13 cycles/degree; Below Normal = <13 cycles/degree to ≥ 6.4 cycles/degree; Poor = measurable acuity <6.4 cycles/degree; Blind/Low Vision = can detect only the 2.2-cm-wide stripes on the Low Vision Teller acuity card at any distance and at any location in the visual field, light perception only, or no light perception. Visual acuities in the Poor and Blind/Low Vision categories were classified as unfavorable outcomes.