Comparison of macular parameters in primary open angle glaucoma patients using cirrus optical coherence tomography

Abstract

Aim: To compare macular parameters using Cirrus optical coherence tomography (OCT) in primary open angle glaucoma (POAG) patients with the normal subjects. Materials and Methods: This observational case control study included primary open angle glaucoma (POAG) patients (n = 184 eyes) and healthy subjects in the control group (n = 184 eyes). All subjects underwent detailed history, complete ocular examination. Complete ocular examination included best corrected visual acuity (BCVA), slit lamp examination, intraocular pressure (IOP), central corneal thickness, Gonioscopy, and dilated fundus biomicroscopy. Field analysis was done by white on white Humphrey Field Analyzer (Carl Zeiss). Optical coherence tomography imaging of macular area was performed using Cirrus HD-OCT. (Cirrus HD-OCT MODEL 4000, Carl Zeiss, Meditec Inc. Dublin CA, 94568).In both these groups, parameters analyzed were central macular thickness (CMT), inner inferior macular thicknesses (IIMT), inner superior macular thicknesses (ISMT),inner nasal macular thicknesses (INMT), inner temporal macular thicknesses (ITMT), and central macular volume (CMV). Results: The POAG group had significantly decreased values of CMT, IIMT, ISMT, INMT, ITMT and CMV compared to control group, Thus, macular thickness and volume parameters may be used for making the diagnosis of glaucoma especially in patients with abnormalities of disc. Statistical analysis done using student t-test. SPSS 13.0 software was used to calculate p value. There was statistically significant difference found in all macular parameters between cases and controls. (p=0.001). Conclusion: Macular parameters, such as total macular volume, inner macular thickness and outer macular thickness can be used in addition to RNFL thickness to aid in the diagnosis of early glaucoma using OCT, in certain conditions, where RNFL parameters may be distorted, such as disk abnormalities or peripapillary atrophy macular parameters may be relied upon. Macular thickness parameters showed thinning in diagnosed cases of glaucoma.