[Possibilities for imaging the retinal nerve fiber layer with the scanning laser ophthalmoscope]

Abstract

Background: Documentation of the retinal nerve fiber layer using red free light is not established as a routine method. The reasons for this are the difficulties involved in taking the pictures and developing them, especially in glaucoma patients, and the need for maximum pupil dilation. The scanning laser ophthalmoscope (SLO) allows fast and easy documentation of the fundus with the possibility of simultaneous image control during the examination.

Patients and methods: Nerve fiber layer images of 48 eyes of 25 patients taken with the argon blue light of the SLO were compared to conventional photographs of the nerve fiber layer with red-free light. In addition, we compared documentation of the nerve fiber layer using argon-blue or argon-green light in the SLO.

Results: The nerve fiber layer images obtained with the SLO were of good quality for all 48 eyes included in the study, whereas with conventional photography we could not obtain images in 9 eyes. There was a high correlation between the two methods in the detection of localized damage or zones with diffuse nerve fiber atrophy for the 39 eyes documented with both methods, and there was better image quality in some using the SLO. The use of blue light permits the nerve fiber layer to be seen more easily than with green light.

Conclusions: The SLO allows nerve fiber bundle defects or diffuse atrophy to be detected similar to conventional fundus photographs using red free light sources. There is no further need to dilate the pupil maximally due to the confocal principle and the scanning technique. The smaller angle of view of the SLO requires fixation movements of the patient being examined for the detection of beginning peripheral nerve fiber bundle defects.