[Fourier analysis of macular local electroretinogram in retinal detachment]

To understand the sites and physiological characteristics of macular dysfunction in retinal detachment (RD) by evaluating fundamental harmonic (1f) and second harmonic (2f) components of flicker local electroretinogram (LERG).

LERG were recorded in 128 eyes of 120 patients to a flicker sinusoidally to 31Hz with a hand-held stimulator with direct visualization of the fundus through dilated pupils.

Compared to controls, patients showed losses of both fundamental and second harmonic amplitudes. The abnormality rates of fundamental amplitude in groups with RD affected time < 1 weeks, 1 approximately weeks, 2 approximately weeks, 4 approximately weeks and > 8 weeks were 15%, 25%, 47%, 76% and 91% respectively; and the abnormality of rates fundamental-second harmonic amplitude ratios (1f/2f) were 5%, 14%, 28%, 64% and 87% respectively. On average, 2f decreased more quikly than 1f and 1f/2f tended to increase with the course of disease. The results show both 1f and 2f descend in the RD eyes with or no macular detachment (P < 0.05). 2f just descend obviously in the 48 macular detachment eyes (P < 0.01), so that 1f/2f ascend in these eyes(P < 0.05). There was a significant relation between amplitudes of LERG in the detached eyes before surgery and best postoperational correct vision in the attached eyes.

In the eyes with retinal detachment, both receptoral and postreceptoral sites contribute to macular dysfunction. The level of macular dysfunction in the eyes with or no macular detachment is different. It would be of clinical value to obtain a fundamental-second harmonic ratio in order to assess the disturbance in the different site of macular. In our opinion: macular flicker local electroretinogram is an important indicator of prognosis to the functional recovery of the attached eye after corrective surgery.