APR 26, 2011
Previous reports from the Early Treatment for Retinopathy of Prematurity (ETROP) Study have shown a beneficial effect of early treatment compared with conventional management on grating visual acuity at nine months corrected age and on recognition (letter) visual acuity at age 6 in the subset of high-risk prethreshold eyes that had type 1 ROP in the neonatal period. But what about visual field results? Reduced peripheral vision is a potentially serious adverse effect of laser treatment.
To learn more, researchers obtained the visual field extent measurements in ETROP participants when they reached age 6 to compare peripheral vision in eyes with zone I and zone II ROP. They found no detrimental effect of early treatment of type 1 ROP. There was a trend to reduced visual field in earlier treated eyes with high-risk type 2 disease, which suggests there may be a slight benefit for mean visual field extent from observing type 2 ROP eyes and treating if and when progression of disease is noted.
Subjects in the current study were 370 study participants who developed high-risk prethreshold ROP and were enrolled in the ETROP Study during a two-year period between 2000 and 2002. When the subjects were six years of age, vision testers used white-sphere kinetic perimetry to measure their visual field extent along the superotemporal, inferotemporal, inferonasal and superonasal meridians.
The extent of the visual field was 0.1 degrees to 3.7 degrees larger in early treatment eyes when blind eyes were assigned a score of 0 degrees. When data were examined from participants with one sighted early treatment eye and one sighted conventional management eye, early treatment eyes showed a small (1.3 to 3.1 degree) reduction, which was statistically significant only along the superonasal meridian (P = 0.005). In bilaterally-sighted children, visual field extent was not significantly reduced for high-risk type 1 early treatment eyes (-0.9 to 1.8 degrees). However, in early treatment eyes with high-risk type 2 disease, visual field extent was significantly smaller compared with that of conventional management eyes (3.6 to 8.7 degrees superonasal field [P = 0.003]; inferonasal field [P < 0.001]).
The authors say the results of the current study suggest that early treatment has no detrimental effect on type 1 ROP eyes, but there may be a slight benefit for mean visual field extent from observing type 2 ROP eyes and treating if and when disease progression is noted. This benefit is consistent across all four quadrants but is greater in the two nasal quadrants (temporal retina) than in the two temporal quadrants (nasal retina).