Abstract
Purpose::
To determine whether there is any correlation between the macular volume and the amplitude of focal macular electroretinogramus (FMERGs) in patients with retinitis pigmentosa (RP).
Methods::
Twenty-six eyes of 26 patients with RP (9 men, 17 women; mean age, 41.7 years), who had visual acuity of 0.3 or better, were studied. FMERGs were elicited by 15-degrees stimulus spot centered on the fovea under direct fundus observation using a modified infrared fundus camera. The macular volume was measured in a 6-mm diameter central retinal region by optical coherence tomography (Stratus OCT, Carl Zeiss Meditec). The FMERGs and macular volumes were also recorded from 20 age-matched normal controls.
Results::
In RP patients, the mean macular volume was 5.98±0.60 mm3, and the mean b-wave amplitude was 1.06±1.09 µV. Both values were significantly smaller in RP patients than those in normal controls (P<0.05). There was a significant correlation between the macular volume and the b-wave amplitude (Spearman's rank correlation; P=0.004, ρ=0.571). FMERGs were detectable for all patients who had a macular volume of >6.5 mm3.
Conclusions::
These results suggest that the decrease in the FMERGs in RP patients is due to a degeneration of the macular region of the retina.
Keywords: retinal degenerations: hereditary • electrophysiology: clinical • imaging/image analysis: clinical