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A. W. Francis, M. E. Gyasi, L. Deng, H. Gong; Risk Factors for Progression to Advanced Glaucoma in Ghana. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4002.
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Advanced glaucoma is a leading cause of blindness in Ghana. This is the first study in Ghana to correlate potential risk factors for glaucoma progression such as advancing age, gender, intraocular pressure (IOP), and increasing cup-to-disc ratio (CDR) using standardized International Geographical and Epidemiologic Ophthalmology (ISGEO) criteria to define moderate and advanced glaucoma.
This was a retrospective case-control study conducted at a large outpatient eye clinic in Accra, Ghana. 164 glaucoma patients were separated into moderate and advanced glaucoma groups. Data was analyzed by linear and logistic regression. For advanced glaucoma, the ISGEO definition requires evidence of severe optic nerve damage satisfied by any one of these criteria:- (1) CDR ≥0.7 or CDR asymmetry ≥0.2 + glaucomatous visual field test (VFT) defect- (2) CDR ≥0.9 or asymmetry ≥0.3, without VFT defect- (3) IOP ≥30 mmHg, afferent pupil defect, no optic disc exam or VFT, and visual acuity light perception or worse (i.e. due to near complete optic nerve fiber loss, the pupil shows no reaction to light plus a corneal scar occluded our view of the fundus).The moderate glaucoma group served as a control for progression to advanced glaucoma. This group had less severe optic nerve damage that satisfied any of these criteria:- (1) CDR 0.7 or 0.8 without VFT defect- (2) CDR <0.7 with a VFT defect- (3) IOP ≥30 mmHg in either eye (30 mmHg= 97.5th percentile for this population).
There were 90 advanced and 74 moderate glaucoma patients. The mean ages were similar (55.55 vs. 55.83 yrs, respectively), but more advanced patients were male (60% vs. 40.5%). No statistical gender variations were found between groups. The advanced patients had a higher mean IOP (32.0 vs. 26.4 mmHg, p<0.001) and a larger mean CDR (0.85 vs. 0.57, p<0.001). Almost all patients (94.7%) with an IOP ≥ 40 mmHg had a CDR ≥ 0.7. The advanced group’s CDR was positively correlated with IOP in both eyes (p=0083 OD; p=0.0001 OS) which indicates a significant relationship between higher IOP and glaucoma progression. The odds of glaucoma progression were 2.5x more likely with an IOP ≥31 mm Hg (OR=2.50, 95% CI (1.33, 4.69)). However, age and CDR were not correlated. Patients older than 65 yrs did have a higher, but not a statistically significant chance of progressing to advanced glaucoma (OR=1.28, 95% CI (0.92, 1.78)).
Our study shows that progression from moderate to advanced glaucoma in Ghana is related to increasing severity of the IOP and CDR relationship, but is not necessarily related to advancing age or gender independent of other variables.
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