Clinical correlation between optic disc changes and visual field defects in patients of primary open angle glaucoma at a tertiary care center

Aim: To evaluate optic disc changes and changes in the visual field, and to establish a correlation between structural and functional damage in glaucomatous eyes.
Material and Methods: The present study is a prospective observational study. It was carried out in the Department of Ophthalmology, at Shri Ram Murti Smarak Institute of Medical Sciences, Bareilly from April 2013 to April 2014. Seventy primary open angle glaucoma subjects constituted the study material for this prospective study. These patients were evaluated for optic nerve head changes and visual field changes.
Results: The study comprised of 70 cases of glaucoma that includes 39 males and 31 females. The prevalence of POAG was highest among 51-60 yrs age group, 38 (50.66%) of which 26 (34.66 %) were male and 12 (16.00%) were female. Majority of the POAG patients had C:D ratio between 0.6 – 0.7. Out of 136 eyes, 72 (52.94%) had C:D ratio at presentation in the range of 0.6 – 0.7. There was considerable overlapping among different ONH findings. Co-existent disc, vascular and peripapillary changes was very common. Purely diffuse field loss due to glaucoma was observed in 8% eyes, whereas, combination of localized and diffuse field loss was present in majority of eyes. Of all eyes (n = 136), 48 had no defect. Upper field defects were found in 39 eyes; 35 eyes had lower field defects and combined defect was found in 12 eyes. Of the upper and lower cases, the type of defects included nasal step in 24 eyes, arcuate defect in 29 eyes and nasal & temporal quadrant involvement in 41 & 4 eyes respectively. Diffuse RNFL loss was found in 34 eyes with definite visual field defect in all (100%) cases. Localized RNFL damage was present in 22 eyes, among which 20 eyes were found to have definite field loss but 2 eyes showed no VFD in automated perimetry.
Conclusion: There are significant correlations between the parameters of optic disc and MDs of HFA in all patients with open angle glaucoma. Thus the visual field defect in the patients of primary open angle glaucoma corresponds to optic disc cupping and neuroretinal rim loss.