Optic Nerve Head Morphometry in Turkish Primary Open–Angle Glaucoma and Ocular Hypertensive Patients and Its Correlation With the Central Corneal Thickness

Abstract

Purpose: : To evaluate the optic nerve head (ONH) characteristics of primary open–angle glaucoma (POAG) patients and ocular hypertensive (OHT) subjects using the Heidelberg Retina Tomograph II (HRT II) and correlate the topographic parameters with the central corneal thickness (CCT) measurements using ultrasonic pachymetry.

Methods: : The study included one eye of 113 POAG patients (74 women, 39 men; mean age of 61.03 (SD 9.31) years) and 144 OHT subjects (115 women, 29 men; mean age of 56.74 (SD 10.40) years). The POAG group was further classified according to disc area (Group I disc area <2.2 mm², II between 2.2 and 2.8 mm², III >2.8 mm²) and pachymetric measurements with a cut–off value of 555 µm. ONH topographic parameters were compared between the groups according to gender, disc size and pachymetric measurements and a p value <0.05 is considered as statistically significant.

Results: : There were significant differences in all of the ONH topographic parameters between POAG and OHT groups (p<0.001). Mean disc area of the OHT group (2.05 + 0.38 mm²) was significantly smaller than the POAG group (2.27 + 0.55 mm²). The parameters did not differ according to gender (p>0.05). In the POAG group, cup area, C/D area, rim area, cup volume, lineer C/D, mean cup depth and cup shape parameters were lower and rim /disc area was higher in group I when compared with groups II and III. OHT subjects had significantly higher CCT measurements (mean 582.21 (SD 26.68) µm) than the glaucoma group (mean 548.65 (SD 30.03) µm), however the CCT measurements did not show any correlations with the topographic parameters either in the POAG or the OHT groups.

Conclusions: : Corneal thickness might be an important contributing factor in the development of glaucoma in patients with high intraocular pressure (IOP), however it does not seem to be correlated with the amount of glaucomatous optic nerve damage in established glaucoma patients.

Keywords: imaging/image analysis: clinical • optic disc • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)