Purpose To evaluate retinal fonction in patients with dense visual field defects (VFDs) following macular surgery (MS) by recording flicker electroretinograms (ERGs) It has been previously shown (Baker et al., J Physiol 407: 155, 1988) that the fundamental (F1) and second harmonic (F2) components of the 8 Hz flicker ERG are dominated by the activity of distal and proximal retinal layers, respectively. Methods Ten patients who had undergone uncomplicated vitrectomy for MS, 6 with dense, wedge-shaped peripheral VFDs and 4 with normal VFs, were examined at 1, 3 and 6 months after surgery Ten age-matched normal subjects served as controls. ERGs were recorded in response to full-field, sinusoidally flickering stimuli, modulated at several temporal frequencies (TFs) between 5 and 52 Hz. Amplitudes and phases of the ERG Fl and F2 components, isolated by Founer analysis, were measured Ganzfeld flash ERGs were also recorded for comparison. Results. When compared to control subjects, patients with VFDs had normal Fl but reduced F2 amplitudes, with greatest losses (0.5 LU) around the peak (8-10 Hz) of the normal TF function. Patients with normal VF had normal Fl and F2 amplitudes Fl and F2 phases were normal in both patients' groups Ganzfeld flash ERGs showed a decreased b/a wave ratio in patients with VFDs but not in those with normal VFs. F2 and b/a ratio losses in patients with VFDs did not change over the follow-up period. Conclusions. The results indicate that dense VFDs following MS are associated with a selective dysfunction of proximal retinal layers, suggesting that intraoperative ischémie, mechanical damage, or both, to inner retina are implicated in the pathogenesis of these defects.
|Journal||Investigative Ophthalmology and Visual Science|
|Publication status||Published - 1997|
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