Evaluation of Retinal Nerve Fiber Layer Thickness with Spectral Domain Oct in Primary Open Angle Glaucoma and Ocular Hypertension

Esra Şahli

doi:10.4172/2155-9570.1000247

Abstract

Purpose: To compare Primary Open Angle Glaucoma (POAG), Ocular Hypertension (OHT) and control groups by using Visual Field (VF) and Spectral Domain Optical Coherence Tomography (SD-OCT) and to investigate correlations between VF global indices and Retinal Nerve Fiber Layer (RNFL) thickness measurements. Methods: Forty patients with POAG, 55 patients with OHT, and 40 normal subjects were included in the study. All subjects were evaluated by standard automated perimetry and Cirrus HD-OCT. Results: RNFL global average thickness, average thicknesses in four quadrants and at 1 o’clock, 4 o’clock, 5 o’clock, 6 o’clock, 7 o’clock, 10 o’clock, 11 o’clock and 12 o’clock areas in POAG patients were significantly decreased compared with the OHT and the control groups. RNFL thicknesses at 2 o’clock, 8 o’clock and 9 o’clock areas in the POAG group were significantly lower than control subjects. There were statistically significant and a negative correlation between PSD and RNFL global average thickness, RNFL thicknesses in temporal quadrant and at 1 o’clock and 2 o’clock areas in the POAG group. According to the areas under the ROC curve, the parameter which has the best diagnostic ability was found as RNFL thickness in the superior quadrant. The sensitivity and specificity of Cirrus HD-OCT for RNFL thickness in superior quadrant were found 77% and 87%. Conclusion: The correlations between MD, PSD and RNFL thickness parameters could represent the consistency of functional and structural tests. RNFL measurement with SD-OCT could provide important information for detection of early stages of glaucoma.

Highlights

Glaucoma is the leading cause of irreversible blindness in the world
There were statistically significant and positive correlation between Mean Deviation (MD) and Retinal Nerve Fiber Layer (RNFL) global average thickness, RNFL thicknesses in superior, inferior, and temporal quadrants and at 1 o’clock, 2 o’clock, 5 o’clock and 6 o’clock areas; negative correlation between Pattern Standard Deviation (PSD) and RNFL global average thickness, RNFL thicknesses in temporal quadrant and at 1 o’clock and 2 o’clock areas in the Primary Open Angle Glaucoma (POAG) group (Table 2)
According to the areas under the Receiver Operating Characteristic (ROC) curve, the parameter which has the best diagnostic ability was found as RNFL thickness in the superior quadrant (AUC=0.83, p

Summary

Introduction

Glaucoma is the leading cause of irreversible blindness in the world. Primary Open Angle Glaucoma (POAG) is the most common type of glaucoma. POAG can be considered chronic, progressive optic neuropathy that is accompanied by a characteristic cupping and atrophy of the optic disc, Visual Field (VF) loss, open angles, and no obvious ocular or systemic reason [1]. Glaucomatous optic neuropathy causes progressive death of retinal ganglion cells and their axons. These structural changes precede VF defects as measured by standard automated perimetry. The peripapillary Retinal Nerve Fiber Layer (RNFL) thickness evaluation is a useful method to detect the early structural damage of glaucoma [2]. Optical Coherence Tomography (OCT) provides an objective and quantitative measurement of RNFL thickness by measuring echo time delay and intensity of backscattered light from different retinal layers using a low coherence interferometry [2,3]

Objectives

Methods

Results