On- and off-responses of the photopic electroretinograms in X-linked juvenile retinoschisis

PURPOSE: To examine the physiologic condition of the middle retinal layer o f patients with X-linked juvenile retinoschisis (xlRS) by studying the on- and off-responses of the photopic electroretinograms (ERGs). METHODS: Eleven unrelated Japanese men (mean age; 24.9 +/- 7.6 years) who w ere clinically diagnosed with xlRS and molecularly confirmed as having XLRS 1 mutations were investigated. For the photopic ERGs, the a-, b- and d-wave amplitudes elicited by long duration stimuli were recorded, and the respon ses from the xlRS patients were compared to those recorded from normal subj ects (n = 14, mean age, 27.5 +/- 4.5 years). We also examined the relations hip between the photopic ERG responses and the genotype. RESULTS: No significant difference was found between the a- and d-wave ampl itudes in the xlRS patients (34.2 +/- 8.7 muV, 52.5 +/- 10.4 muV, respectiv ely), and those in normal subjects (40.4 +/- 10.3 muV, 44.7 +/- 6.3 muV, re spectively). The mean b-wave amplitude in the xlRS patients was significant ly smaller (10.5 +/- 7.7 muV) than the mean of normal subjects (46.4 +/- 10 .2 muV) (P < 0.0001). No significant correlation was found between the ERG responses and the locus of the mutation. CONCLUSION: The photopic ERG demonstrated considerable impairment of the on -pathway arising from an abnormality of the on-bipolar cells or possibly se condary to Muller cell abnormality in xlRS. (Am J Ophthalmol 2001;131:489-4 94. (C) 2001 by Elsevier Science Inc. All rights reserved).