Analysis of Optic Disc and Vertical Cup Disc Ratio among Glaucoma Suspects in a Black Population

Aim: To analyze the optic discs and vertical cup disc ratio in a black population.

Method: This is a retrospective study of glaucoma suspects who presented to the clinic. Medical history was recorded and comprehensive ocular examination done on each of the subjects. Ocular examination included visual acuity, visual field, tonometry and ophthalmoscopy. Instruments used during the research were Pen torch for examination of the external structures of the eyes, Keeler ophthalmoscopes for fundus examination, Snellen’s charts both literate and illiterate charts for visual acuity assessment, Reichert AT 555 Auto non-contact tonometer for measurementof the intra-ocular pressure.

The optic discs were analyzed using Optical Coherence Tomography machine. Data was analyzed using the statistical package EPI info version 6.04d, a software package designed by the Centers for Disease Control and Prevention (CDC), USA in 2001.

Results: This study included total of 240 optic discs of 120 participants comprising 60 males and 60 females were examined with a mean age of 42.8±13.79; the age range was 19 to 75 years. Very Small discs (<1.0mm) 3 accounted for1.3%, Small discs (1.0-1.3mm) 4 accounted for 1.7%, Medium (1.4-1.7mm) 67 accounted for 27.9%, Large (1.8-2.0mm) 58 accounted for 24.2% while Very Large (>2.0mm) 108 accounted for 45.0% in this study.

VCDR was noticed to have increased with increasing disc diameter. Optic disc diameter increased with increasing RNFL thickness as well (p < 0.05; r = 0.18).

All the very small as well as the small discs were cupped 3% (n = 7/240), 14.6% (n = 35/240) of the medium to very large are also cupped while the remaining 82.5% ( n = 198/240) are normal.

Conclusion: There was no significant correlation between disc diameter and VCDR. There was also a weak positive correlation between the optic disc diameter and the retinal nerve fiber layer thickness of the subjects, such a correlation may be the result of either an increased number of nerve fibers in eyes with larger discs or a smaller distance between the circular scan and the true optic disc margin.