Improved Reading Performance in Patients with Congenital Nystagmus fitted with Soft Contact Lenses

Purpose: To investigate if soft contact lens wear improves visual function, specifically reading performance, in patients with vision loss due to congenital nystagmus. Methods: Three low vision patients (15-18 years of age) with congenital nystagmus from retinopathy of prematurity (ROP), optic nerve hypoplasia (ONH), and congenital cataracts (CC), respectively, participated in this study. Refraction was performed to obtain the BCVA (best corrected visual acuity) before and after contact lens fitting. Semi-scleral soft lenses with a base curve of 8.3 or 8.6mm were used. In two cases, soft contact lenses were prescribed in conjunction with spectacles with color filters. Five dependent variables were examined: (1) BCVA (in logMAR), (2) nystagmus frequency (times/sec), (3) nystagmus amplitude (mm), (4) reading duration (min), and (5) reading error (words/session). Recording of data was carried out five times per week, Monday through Friday, at baseline and at first, second and third weeks after lens wear. Results: All three patients showed improvement after spectacle or contact lens correction. The ONH case alone showed significant improvement in BCVA between pre and post contact lens wear with decreases in nystagmus frequency (F=6.857, p=0.004) and amplitude (F=39.057, p<0.001) post contact wear. In all cases, contact lens wear proved effective in increasing reading duration (ROP: F=54.729, p<0.001; ONH: F=24.236, p<0.001; CC: F=7.602, p=0.002) and decreasing reading error (ROP: F=11.142, p<0.001; ONH: F=50.743, p<0.001; CC: F=30.838, p<0.001). In addition, all patients reported reduced glare disability and chromatic aberration. Conclusions: Our results showed that soft lens wear improves reading performance and, in the OHN case, dampens nystagmus. These effects appear to result predominantly from higher foveation quality and broadening of gaze angles, as well as, in part, from improvement in visual acuity and stimulation of the afferent sensory nerves.