Abstract
PurposeTo describe a new technique to record focal macular electroretinograms (FMERGs) during vitrectomy to assess macular function.MethodsIntraoperative FMERGs (iFMERGs) were recorded in ten patients (10 eyes) who undergo vitrectomy. iFMERGs were elicited by focal macular stimulation. The stimulus light was directed to the macular area through a 25 gauge (25G) glass fiber optic bundle. Background light was delivered through a dual chandelier-type light fiber probe. Focal macular responses elicited with combinations of stimulus and background luminances were analyzed.ResultsA stimulus luminance that was approximately 1.75 log units brighter than the background light was able to elicit focal macular responses that were not contaminated by stray light responses. Thus, a stimulus luminance of 160 cd/m2 delivered on a background of 3 cd/m2 elicited iFMEGs from only the stimulated area. This combination of stimulus and background luminances did not elicit a response when the stimulus was projected onto the optic nerve head. The iFMERGs elicited by a 10° stimulus with a duration of 100 ms and an interstimulus interval of 150 ms consisted of an a-, b-, and d-waves, the oscillatory potentials, and the photopic negative response (PhNR).ConclusionsFocal ERGs with all components can be recorded from the macula and other retinal areas during vitreous surgery. This new technique will allow surgeons to assess the function of focal areas of the retina intraoperatively.
Highlights
In 1981, Miyake et al developed a system to record focal macular electroretinograms (FMERGs) from humans [1]
This combination of stimulus and background luminances did not elicit a response when the stimulus was projected onto the optic nerve head
The Intraoperative FMERGs (iFMERGs) elicited by a 10° stimulus with a duration of 100 ms and an interstimulus interval of 150 ms consisted of an a, b, and d-waves, the oscillatory potentials, and the photopic negative response (PhNR)
Summary
In 1981, Miyake et al developed a system to record focal macular electroretinograms (FMERGs) from humans [1]. There are essentially three ways to deliver a stimulus to a specific area of the retina under fundus observation; through a fundus camera as is done with the Miyake system [2,3,4,5,6,7], through a slit-lamp microscope[8,9], or through a direct ophthalmoscope [10]. All of these methods are non-invasive and performed in the clinic, and several investigators have evaluated the macular function in different macular diseases with one of these methods. The assessments were made before and after therapeutic interventions including vitreous surgery [11,12,13,14,15,16,17,18], and were made to determine the functional properties of the retina of eyes with hereditary macular dystrophies [19,20,21]
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