Regional assessment of cone system function following uncomplicated retinal detachment surgery.

Purpose: To evaluate regional cone system function after uncomplicated retinal detachment (RD) surgery, by recording focal electroretinograms (FERGs) from the central and paracentral regions of the posterior pole.

Methods: FERGs in response to either a central (eccentricity: 0-2.25 deg) or a paracentral annular (2.25-9 deg) uniform field, presented on a light adapting background and sinusoidally flickered at 41 Hz (95% modulation depth, 93 cd/m(2) mean luminance) were recorded from 16 eyes (16 patients) 2 weeks to 420 months following uncomplicated RD surgery (encircling procedure with or without scleral buckling). Pre-operatively, 10 out of 16 eyes had a macular RD. Mean time elapsed from onset of symptoms to surgery was 20 days (range: 5-90 days). Post-operatively, visual acuity ranged 0.1 to 1.0. Eight age-matched normal subjects served as controls. Amplitude and phase of the FERG fundamental harmonic were measured.

Results: Compared to control eyes, affected eyes' central and paracentral FERGs were on average reduced in amplitude (by 40% and 28%, respectively, p<0.01) and delayed in phase (by 70 and 100 degrees, respectively, p<0.01). Eyes with a macular RD did not differ in FERG amplitude or phase from eyes that had a peripheral RD. In individual affected eyes, central, but not paracentral FERG amplitudes were negatively correlated (p=0.05) with time elapsed from onset of symptoms to surgery.

Conclusions: Central and paracentral cone system dysfunction may be detected even at lengthy time intervals from retinal reattachment, independent of the presence of a pre-operative macular RD. The extent of central loss appears to be inversely related to RD duration, in agreement with previous reflectometric findings on foveal cone photopigment density [Liem et al., 1994; Ophthalmology 10: 1945-51].