In the population of RP patients, different types of PVEP waveform alterations can be observed. The appearance of both the responses with decreased amplitude and those with broad, doubled P100 waves might reflect differences in central retinal degeneration. The significance and pathological background of these PVEP alterations need further investigations.

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The results suggest highly variable central responses and groups of cones with preserved function in areas previously considered nonresponsive. The high variability of the central responses could be a result of variable foveal cone density, with differences in inheritance- and duration-related cone degeneration at the time of the examination. The authors stress the value of step-by-step analysis of the trace array of the mfERGs, which can reveal the still-functioning groups of cones.

ABSTRACT.Purpose: The goal of our study was to compare the case histories and clinical findings in three young patients (aged <50 years) who had undergone their first attack of non-arteritic ischaemic optic neuropathy (NAION). We intended to consider whether NAION at a relatively young age might comprise a separate pathological and diagnostic entity. Results: All three cases revealed some common characteristics. All of them experienced recurrent attacks with bilateral manifestations that led to severe loss of vision and visual field defects. The patients had also suffered from diabetes mellitus for a long time, but none of them had diabetic retinopathy. Conclusion: The case histories of these relatively young patients showed some differences, including recurrences and more severe loss of vision, to those of elderly patients. However, all the signs we found had been reported previously, although much less frequently, in NAION cases among elderly patients. The clinical and laboratory findings definitely exclude the possibility of an alternative diagnosis. Hence, our results do not support the notion of a different pathomechanism of NAION at a young age and its existence as a separate disease entity.

Our results provided no evidence for the advantage of either binocular or monocular stimulating conditions in obtaining mfERGs. A considerable side difference was found between the mfERGs of the two eyes in almost all individual cases.