A comparative study of two methods of optic disc evaluation in patients of glaucoma

Abstract

Introduction: Glaucoma is a progressive disorder and requires serial evaluation in order to monitor disease progression and optimize therapy. Objective: The objective of this study was to determine the correlation between each of cup/disc (C/D) ratio and the disc damage likelihood scale (DDLS) with retinal nerve fiber layer (RNFL) and global indices in Humphrey field analyzer II (HFA II). Design: Cross-sectional study. Materials and Methods: A total of 50 patients diagnosed with primary open angle glaucoma were examined to grade DDLS score and C/D ratio. The average (avg) RNFL was obtained using the Fast RNFL protocol on optical coherence tomography (OCT) (4.0.2 Carl Zeiss). HFA II Swedish Interactive Threshold Algorithm Standard 24-2 visual fields were obtained within 1 month of clinical examination. The correlation of C/D ratio with avg RNFL thickness, Mean deviation and Pattern standard deviation was calculated by Pearson correlation coefficient (r). Similar coefficients were obtained for DDLS. Results: The P value for the difference in the r between C/D ratio with RNFL (−0.628) and DDLS with RNFL (−0.8369) was significant (P < 0.01) when correlation of C/D, DDLS with RNFL was considered. Conclusion: The DDLS shows stronger correlation with structural changes in OCT than C/D ratio. The disc diameter and rim width increases the value of clinical optic disc examination.

Keywords

• Cup/disc ratio
• disc damage likelihood scale
• retinal nerve fiber layer thickness
• visual field