Correlation of Vertical Cup Disc Ratio and Matrix FDT Mean Deviation in Primary Open Angle Glaucoma Patients

Abstract

Objectives: To evaluate the correlation between glaucomatous structural change using vertical-cup-disc ratio of the optic nerve head and functional loss measured by Frequency Doubling Technology perimetry. Materials and methods: It was a retrospective observational clinic-based study of 77 newly diagnosed Primary Open Angle Glaucoma (POAG) patients from a Private Eye clinic in a suburb of Port Harcourt city, Nigeria. They underwent clinical fundal examination with slit-lamp biomicroscope (Perkin’s slit-lamp) with 90D (Volk) lens; and Frequency Doubling Technology perimetry 24-2 threshold (Humphrey Matrix 800, 2011 Carl Zeiss Meditec, Dublin, California). The Vertical-cup-disc-ratio was assessed for each eye and the Mean deviation calculated for each eye. The relationship between VCDR and mean deviation was evaluated using Pearson’s correlation coefficient regression analysis. Result: There were 24 males (31.17%) and 53 females (68.83%). The mean age of the patients was 56.65 ± 14.33 years with a range of 37-78 years. The mean VCDR was 0.83±0.09 and 0.78±0.13 for the right and left eyes, respectively while mean FDT mean deviation was -13.99±9.33Db and -11.9.22Db for the right and left eyes, respectively. The VCDR significantly correlated with FDT mean deviation (Pearson Correlation Coefficient, r= -0.923, r2= 0.852, p-value=0.001 for the right eye; r= -0.915, r2=0.836, p-value=0.001 for the left eye. Conclusion: This study shows that at least 80% of VCDR correlated with the Mean deviation of matrix FDT amongst this cohort of POAG patients. it buttresses the fact that clinical evaluation of the optic nerve remains an indispensable tool in glaucoma diagnosis and can use to assess glaucoma severity in resource poor setting where visual field machine is not available.