Abstract
Purpose:
Amblyopia is a form of cerebral visual impairment in the absence of an organic cause. Attenuated amplitudes and prolonged latencies are common abnormalities found in pattern reversal visual evoked potentials (PRVEP) in amblyopic eyes. However there is scarce data on PRVEP in fellow eyes of amblyopes. The aim of this study is to evaluate visual acuity and PRVEP in the fellow eye of strabismic and/or anisometropic amblyopic children.
Methods:
This study was approved by the Ethics Committee of the Federal University of São Paulo (0503/08). The amblyopic group consists of 40 children (22 girls), aged 5-14 years (mean 8.7±2.2 years), 15 anisometropic, 21 strabismic and 4 with anisometropia and strabismus. A group of 19 healthy children (13 girls) aged 5-15 years (8.2±2.6 years) was used as control. Visual acuity was measured in logMAR from each eye with the best optical correction using the ETDRS chart for distance. Grating acuity was measured from each eye using the sweep-VEP system. Transient PRVEP recording was obtained with checkerboard stimuli subtending 1°, 15' and 7.5' visual angles from both eyes in monocular stimulation condition according to ISCEV protocol. P100 latency in milliseconds (ms), the amplitude between the peaks of N75 and P100 in microvolts (μV) were determined.
Results:
Statistically worse visual acuity for either optotype (0.04±0.1 logMAR; p=0.021,) or grating acuity (0.07±0.05 logMAR; p=0.026,) were found when compared with healthy children (0.0±0.0 logMAR optotype, 0.05±0.04 logMAR grating). Significantly prolonged P100 latency for stimulus 7.5’ in the felllow eye (110.9±11.4) was detected when compared with controls (103.2±6.8; p=0.01,). There were not a statiscally significant difference between the amplitude of the control group and the fellow eye for all stimulus (p=0.496, 0.700 and 0.422 for 1°, 15' and 7.5' visual angles, respectively).
Conclusions:
When compared with eyes of healthy children, fellow eyes of amblyopic children showed worse optotype and grating acuity, with subtle abnormalities in the PRVEP detected as prolonged latencies for smaller size stimuli. These findings confirm previous studies showing that the fellow eye of amblyope patients is not fully normal.
Keywords: 507 electrophysiology: clinical •
754 visual acuity •
417 amblyopia