Macular function in eyes with open-angle glaucoma evaluated by multifocal electroretinogram

Abstract

Purpose: To evaluate macular function in patients with open-angle glaucoma (OAG) by means of multifocal electroretinogram (mfERG).

Methods: Twenty-four OAG patients (mean age 54.6 ± 9.1 years) and 14 age-similar controls were enrolled. OAG patients had intraocular pressure (IOP) less than 18 mm Hg with topical medical treatment, 24-2 visual field (Humphrey Field Analyzer [HFA]) with mean deviation (MD) between -2 and -12 dB, and corrected pattern standard deviation (CPSD) between +2 and +10 dB and no history or presence of cataract and/or macular disease. MfERGs in response to 61 M-stimuli presented to the central 20° of the visual field were assessed in OAG patients (24 eyes) and in controls (14 eyes). Ring (R) analysis was performed every five retinal eccentricities in areas between the fovea and midperiphery: 0° to 2.5° (R1), 2.5° to 5° (R2), 5° to 10° (R3), 10° to 15° (R4), and 15° to 20° (R5). MfERG response amplitude density of the N1-P1 components (N1-P1 RAD, nV/deg(2)) and P1 implicit time (P1 IT, ms) of the first-order binary kernel were measured for each ring.

Results: OAG patients showed a significant (P < 0.01) decrease in N1-P1 RADs and an increase in P1 IT in both R1 and R2 with respect to controls. The reduction in N1-P1 RADs was significantly (P < 0.01) correlated with HFA MD and CPSD. No other significant differences between OAG and controls were found.

Conclusions: OAG patients show macular dysfunction detectable by the mfERG technique. Since the mfERG N1-P1 component is thought to be generated by preganglionic elements (photoreceptors and OFF bipolar cells), our data support the functional impairment of the neural generators of the macular region in patients with glaucoma.