Correlation of visual field parameters with parameters of papillotopometry and nerve fibre layer thickness measurements in primary open angle and normal tension glaucoma
S. Kremmer, S. Sievers, N. Niederdräing, N. C. Bontke, K.-P. Steuhl
In the last years, scanning laser techniques have been established especially for optic disk topometry in glaucoma diagnostics (scanning laser topometry, SLT). Recently, a new software version of TopSS (3.0.19, LDT Inc., USA) and a new generation of scanning laser polarimeters (SLP) for retinal nerve fiber layer thickness (NFLT) measurements are available (GDx, 1.0.08, LDT Inc., USA). Aim of the present study was to evaluate wether there is a correlation between visual field parameters and SLT or SLP in patients with primary open angle glaucoma (POAG) and normal tension glaucoma (NTG).
Patients and Methods: We examined 63 POAG-patients (age 65.18 y, +/- 12.22 y; 31 female, 32 male) and 40 NTG-patients (age 64.38 y, +/- 9.19 y; 19 female, 21 male). In automated perimetry (Oculus, TAP cc 2000), visual fields were evaluated according to their mean defect (MD) and to the glaucoma classification of Aulhorn (GCA). In SLT measurments, we considered vertical and horizontal optic disk dia- meter and C/D-R, neuroretinal rim (NRR), average depth and slope as well as the volume below and above the average retinal level. In SLP, we evaluated NFLT in the superior and inferior sector, the superior to temporal ratio (S/T-R), the inferior to temporal ratio (I/T-R), the superior to nasal ratio (S/N-R), the max. modulation (mm) and a theoretical value "the number".
Results: In POAG patients, the SLT parameters NRR, C/D-R and volume above correlated with MD and GCA, in NTG only the vertical C/D-R. In SLP measurements, however, MD and GCA correlated best with S/T-R, I/T-R and mm in both, POAG and NTG. Only in NTG the S/N-R showed a significant correlation to visual field parameters, whereas "the number" correlated with MD and GCA in POAG.
Dicussion: In POAG patients, the quantitative visual field parameter MD and the more qualtitative GCA showed a large degree of consent in their correlation to SLT and SLP measurements. In NTG patients, the correlation between SLP results and visual field parameters was markedly higher than in SLT measurements. These findings are in accordance to the clinical observation that NTG patients often present with pathological optic disks but relative mild visual field defects.
University Eye Hospital, Hufelandstr. 55, 45122 Essen