Pattern electroretinography of larger stimulus field size and spectral-domain optical coherence tomography in patients with Stargardt disease.

AIMS: To investigate the importance of a larger stimulus field for pattern electroretinography (PERG) in evaluating macular function in Stargardt disease, and to determine the relationship between PERG and spectral-domain optical coherence tomography (SD-OCT). METHODS: In this prospective cross-sectional study, PERG from standard (12 degrees x 16 degrees ) and larger (24 degrees x 32 degrees ) stimulus fields and SD-OCT were recorded in 18 patients with genetically confirmed Stargardt disease, and in 18 control subjects. RESULTS: A PERG P50 response to the larger stimulus field was detectable in 86% of eyes, with a mean P50 amplitude of 2.3 microV, compared with 22% and 1.0 muV for the standard stimulus field. The specificity and sensitivity of PERG to the standard stimulus field were greater than for the larger field. For both PERG P50 and N95, the differences in their amplitudes between the standard and larger stimulus fields correlated significantly with visual acuity and SD-OCT parameters. CONCLUSION: The higher sensitivity and specificity of PERG to the standard stimulus field provide detection of early maculopathy in Stargardt disease, while PERG with the larger stimulus field allows for longer follow-up. The PERG amplitude for the larger stimulus field correlated with severity of transverse photoreceptor loss in SD-OCT. These methods are complementary for evaluation of progression of photoreceptor damage in patients with Stargardt disease.

Mapping of central visual function by microperimetry and autofluorescence in patients with Best's vitelliform dystrophy.

PURPOSE: To evaluate retinal sensitivity and fixation patterns in patients with Best's dystrophy by microperimetry (MP) and to correlate the results with static perimetry and retinal morphology seen by autofluorescence (AF). METHODS: Central 10 degrees visual fields in 11 patients with Best's dystrophy (VA: 0.5+/-0.38) were recorded by the Octopus M2 TOP program and by MP (MP1, Nidek Technologies). AF was recorded by HRA (Heidelberg Engineering). RESULTS: High correlation (R=0.75, -0.76, -0.48) was found between static perimetry (MS, MD and CLV indices) and MP. Based on MP and AF results, three groups of patients were formed. Patients in the first two groups fixated inside the central nonuniform hypo- and hyperfluorescent AF ring area, next to relative (Group 1) or absolute scotoma (Group 2). Inner parts of the retina close to the fovea were most affected, whereas regions closer to the periphery of the 10 degrees visual field showed near normal function. As the disease progressed, there was an evident shift of fixation to preferential retinal locus (PRL) in eight eyes with visual acuity 0.2 or less (Group 3). Fixation shift was superior in four eyes, temporal in two eyes, and nasal in two eyes. CONCLUSION: MP enabled a highly sensitive topographic monitoring of retinal function, showing central or pericentral fixation in the early stages, until loss of central function, in eyes with VA 0.2 or less, caused evident shift of fixation to PRL. PRL was never situated inside the central uniform hypofluorescent area, but corresponded with the hyperfluorescent ring seen with AF imaging.

Pattern ERG and psychophysical functions in Best's disease.

The aim of the study was to asses the neurosensory retinal function in 12 patients (24 eyes) with different stages of Best's disease, by determining how pattern and full field flash ERG responses were related to visual acuity, stage of disease and extent of visual field loss. All patients had typically abnormal EOG responses and normal full field-flash ERG responses. Patients were stratified in two groups according to visual acuity. In the first group 12 eyes with visual acuity better than 0.5, all amplitudes and latencies of PERG P50 and N95 responses were in the normal range. Small central scotoma was detected by static perimetry in four of these eyes. In the second group of 12 eyes with visual acuity 0.5 or less, PERG showed reduced both P50 and N95 amplitudes in five eyes, and N95 solely, in two eyes. All patients had central scotomas detected by static perimetry. Progression of the disease, seen in deterioration of visual acuity and progression of central visual field defects, corresponded well with reduction of both PERG P50 and N95 amplitudes. There was no correlation found between visual acuity and EOG responses. Our results show that in Best's distrophy, pattern ERG is getting abnormal with progression of the disease, indicating relative preservation of neurosensory retina in initial stages of the disease. In contrast to EOG - being abnormal in all the patients regardless of the stage of disease - and full field-flash ERG - being normal in most of the patients - PERG gives opportunity for electrophysiological determination of the progression of the disease.