Purchase this article with an account.
I. Cunningham, A. Chandna, F. Pennie, W. Newman, S. Chen, A. Norcia; Contrast Sensitivity Deficits in Bilateral Pseudophakic Children Using Pelli-Robson Chart and Steady State Visually Evoked Potentials. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5887.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The disruptive effects of partial cataracts during early visual development are unknown. Unlike dense cataracts in childhood that require surgical extraction to restore vision, guidelines for removing partial cataracts are subjective and controversial. We have utilised the steady state visual evoked potential (SSVEP) paradigm to measure contrast sensitivity deficits in older pseudophakic children with an aim to develop the technique for infants with partial cataracts. Contrast develops earlier than acuity and may be an important predictor for measuring level of visual disruption. Therefore, contrast was measured using two different tests in pseudophakic children with a history of partial cataracts by SSVEP and the standard Pelli-Robson (PR) chart.
Monocular contrast function was measured in six bilateral pseudophakic children. Partial cataracts were surgically removed with implantation of intraocular lens when the standard clinical criteria were met. SSVEP contrast stimuli were swept between 2 (low-contrast) and 80% (high contrast) using pattern-reversal modulation. Temporal frequency ranged from 3.76 to 7.51Hz with fixed spatial frequency at 2cpd. PR charts were scored by identification of each letter; then converted from log into percentage contrast. Both eyes were included in analysis and divided into two groups; dominant (dom) and non dominant (non-dom) eye.
Cataracts were surgical extracted at a mean age of 6.5±2.2yrs (Range: 0.3-15.4yrs). The mean age at time of test was 11.2±1.6yrs (range: 6.6-18.2yrs) with an average time of 4.7±1.2yrs since the cataract was removed. Mean contrast sensitivity for dom eye (PR: 2.10±0.1%; SSVEP: 4.78±1.13%) and non-dom eye (PR: 3.22±0.67%; SSVEP 10.47±2.37)
Contrast sensitivity deficits were found in these children despite optimal management according to current clinical criteria. The level of contrast detected using the PR chart was greater for both dom and non-dom eye than for SSVEP. Both tests were able to identify the dom and non-dom eye although the difference between dom and non-dom eye for SSVEP was greater than using the PR chart. It is possible that SSVEP sweeps across a greater range of contrast that is unable to be tested using PR chart and greater deficits in contrast are measurable indicating a useful role for it’s use in infants.
This PDF is available to Subscribers Only