Scanning laser polarimetry, retinal nerve fiber layer photography, and perimetry in the diagnosis of glaucomatous nerve fiber defects

Retinal nerve fiber layer defects are part of early glaucomatous damage. In the present study, we compared the ability of retinal nerve fiber layer photography (NFP) and scanning laser polarimetry (SLP) to detect nerve fiber layer defects in glaucoma patients. Besides ophthalmological standard examinations, we performed NFP (Zeiss Ikon fundus camera 30 degrees, green filter), SLP (GDx, 1.0.14 and 2.0.09, LDT) and automated perimetry (Oculus, Twinfield, 30 degrees) in 150 glaucoma patients [74 with primary open-angle glaucoma (POAG) and 76 with normal-tension glaucoma (NTG)]. The perimetric results were evaluated according to a modified Aulhorn classification. NFP and SLP were graded according to Quigley. In POAG, 42% of NFP and 5% of SLP were not evaluable. In NTG, 24% of NFP and 4% of SLP were not evaluable. In POAG, NFP and SLP revealed a direct agreement in 54.5%, and in NTG, 55%; there was a small difference of one stage in 39.5% (POAG) and 41% (NTG). In POAG, NFP/SLP showed agreement with perimetric results in 35%/30% of cases and differences of one stage in 56%/58%. In NTG, NFP/SLP agreed with perimetry in 52%/48% of cases and differed by only one stage in 32%/39%. Larger deviations were found in less than 13% of the cases. NFP and SLP mostly showed good agreement or little deviation as to grading of nerve fiber layer damage. In clinical use, SLP has advantages over NFP because a higher rate of good-quality images can be obtained and pupils do not have to be dilated. Additionally, SLP measurements provide quantitative data and a large normative data base exists.