On- and off-responses of the photopic electroretinograms in X-linked juvenile retinoschisis.
OBJECTIVE
To examine the physiologic condition of the middle retinal layer of 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 were clinically diagnosed with xlRS and molecularly confirmed as having XLRS1 mutations were investigated. For the photopic ERGs, the a-, b- and d-wave amplitudes elicited by long duration stimuli were recorded, and the responses from the xlRS patients were compared to those recorded from normal subjects (n = 14, mean age, 27.5 +/- 4.5 years). We also examined the relationship between the photopic ERG responses and the genotype.


RESULTS
No significant difference was found between the a- and d-wave amplitudes in the xlRS patients (34.2 +/- 8.7 microV, 52.5 +/- 10.4 microV, respectively), and those in normal subjects (40.4 +/- 10.3 microV, 44.7 +/- 6.3 microV, respectively). The mean b-wave amplitude in the xlRS patients was significantly smaller (10.5 +/- 7.7 microV) than the mean of normal subjects (46.4 +/- 10.2 microV) (P < 0.0001). No significant correlation was found between the ERG responses and the locus of the mutation.


CONCLUSIONS
The photopic ERG demonstrated considerable impairment of the on-pathway arising from an abnormality of the on-bipolar cells or possibly secondary to Müller cell abnormality in xlRS.
Shinoda
K
K
Department of Ophthalmology, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan. shinodak@med.keio.ac.jp
Ohde
H
H
Mashima
Y
Y
Inoue
R
R
Ishida
S
S
Inoue
M
M
Kawashima
S
S
Oguchi
Y
Y
D000293:Adolescent; D000328:Adult; D004596:Electroretinography; D005136:Eye Proteins / Q000235:genetics; D008040:Genetic Linkage; D005838:Genotype; D006801:Humans; D007395:Interneurons / Q000502:physiology*; D008027:Light; D008297:Male; D009154:Mutation; D017949:Retinal Cone Photoreceptor Cells / Q000503:physiopathology*; D012162:Retinal Degeneration / Q000235:genetics / Q000503:physiopathology*; D014960:X Chromosome
D005136:Eye Proteins; C108726:RS1 protein, human