Genome-wide association study of primary open-angle glaucoma in continental and admixed African populations

Primary open angle glaucoma (POAG) is a complex disease with a major genetic contribution. Its prevalence varies greatly among ethnic groups, and is up to five times more frequent in black African populations compared to Europeans. So far, worldwide efforts to elucidate the genetic complexity of POAG in African populations has been limited. We conducted a genome-wide association study in 1113 POAG cases and 1826 controls from Tanzanian, South African and African American study samples. Apart from confirming evidence of association at TXNRD2 (rs16984299; OR[T] 1.20; P = 0.003), we found that a genetic risk score combining the effects of the 15 previously reported POAG loci was significantly associated with POAG in our samples (OR 1.56; 95% CI 1.26–1.93; P = 4.79 × 10−5). By genome-wide association testing we identified a novel candidate locus, rs141186647, harboring EXOC4 (OR[A] 0.48; P = 3.75 × 10−8), a gene transcribing a component of the exocyst complex involved in vesicle transport. The low frequency and high degree of genetic heterogeneity at this region hampered validation of this finding in predominantly West-African replication sets. Our results suggest that established genetic risk factors play a role in African POAG, however, they do not explain the higher disease load. The high heterogeneity within Africans remains a challenge to identify the genetic commonalities for POAG in this ethnicity, and demands studies of extremely large size

Neovascular glaucoma in a nigerian African population

Objective: To determine the ocular and systemic factors associated with neovascular glaucoma (NVG) in an African population.Design: Hospital based cross sectional study.Setting: Eye clinic, Department of Ophthalmology, University College Hospital, Ibadan, Nigeria.Subjects: Sixty one consecutive patients with clinical diagnosis of NVG seen between January 1995 and December 1999 had a complete ocular evaluation.Results: Among the 61 subjects studied with an identifiable aetiological factor presumably causing neovascular glaucoma, 82% had associated posterior segment diseases producing ischaemia. These were retinal venous obstruction (78.7%), retinal arterial occlusion (1.6%). Those with no identifiable vaso-occlusive disease had couching (11.5%), aphakia with vitreous loss (3.3%) and chronic uveitis (1.6%). Systemic arterial hypertension was present in 62.3% while diabetes mellitus was presentin only 8.3% of the subjects studied. Chronic uveitis and penetrating eye injury were infrequently diagnosed. Chronic open angle glaucoma was present in the other eye of 37.7% of subjects.Neovascular glaucoma was unilateral in 95.1% of subjects. 84.4% of affected eyes were blind on presentation. Males outnumbered females among subjects with NVG above 40 years, while females outnumbered males in the subjects below 40 years of age. Eyes of that were couched constitute a significant proportion of subjects with neovascular glaucoma.Conclusion: Medical conditions such as systemic hypertension, diabetes and ocular conditions like retinal vein, retinal artery occlusion, couching and glaucoma were associated with NVG. Most of these ocular and systemic associations should be identified early and treated to preventneovascular glaucoma in the other eye of the subject

Pattern of corneal opacity in Ibadan, Nigeria

Background: The prevalence and causes of corneal blindness vary from one region of the world to another. There is even variation within the developing countries of Africa. Method: A retrospective review of 675 patients with corneal scarring out of the 3,753 new patients corneal scarring in patients attending the eye clinic of the University College Hospital (UCH) Ibadan over a 5year period. Results: Subjects in age groups 0 to 10years and 21 to 30years were mostly affected. Males were more affected with a ratio of 3:1. Most presentations were in the months of January to March and July to September. Almost half (48.99%) of the patients had uniocular blindness and no case of bilateral blindness from corneal opacity was found. The main causes of corneal opacity were trauma (51.1%) and microbial keratitis (26.70%) both of which are avoidable causes of blindness. No case of trachomatous corneal scarring was found in the group studied. Conclusion

Corneal diameters in infants born in two hospitals in Ibadan, Nigeria

Objectives: To measure the horizontal corneal diameters in infants at birth and compare with values reported in other studies.Design: A cross-sectional hospital based study.Subjects: All the healthy infants born within the period of one month in these hospitals were eligible for enrolment into the study. Horizontal corneal diameter measurements were performed with indirect caliper in both eyes of each of the 342 healthy full term infants and 25 preterm healthy infants born in these two hospitals. These results were evaluated according to the age of the infantsResults: The corneal diameter in term infants was found to range from 9.00 mm to 12.50 mm during the first week of life with a mean of 10.26 mm (SD ± 0.59 mm, n = 64). This is higher than what was reported for Caucasian infants (P < 0.01). Mean horizontal corneal diameter in all male infants aged 1-238 days was 11.06 mm (SD 0.75 mm, n = 187), slightly higher than 10.93 mm (SD 0.22 mm, n = 154) in all females, though this difference was not statistically significant. Horizontal corneal diameter increased progressively with age, from a mean value (SD) of 10.26 mm (0.72) to a mean value (SD) of 12.0 mm at 34 weeks of age. There was no significant difference in the mean corneal diameter of the right and left cornea. A few infants had corneal diameters of 12.50 mm and had nocongenital glaucoma. Mean corneal diameter in preterm infants less than 37 weeks of gestation was 8.90 mm at birth (SD 1.25 mm, n = 25).Conclusion: The horizontal diameter increased with age from birth to the 34 weeks of age. Changes after this period were not studied. The values obtained in these African infants were slightly higher than those reported from other populations

Rapid assessment of cataract blindness among ughelli clan in an urban/rural district of Delta state, Nigeria

Background: A population based, rapid assessment for cataract blindness was conducted in Ughelli North local government area of DeltaState, an urban/rural area of Nigeria between June and July 2001 with the aim of establishing baseline data for developing cataract intervention services for the area. Method: A cluster random sampling method was used based on the guidelines for the Rapid Assessment for Cataract Surgery. A total of 8 clusters of 90 persons were randomly selected from the 8 communities that make up the Ughelli clan. Only people of 50 years and above who had been resident in the area for up to six months were included. A total of 684 persons were examined (91.2% coverage) using a designed survey form. The barriers to the uptake of cataract surgery were also identified during the survey. The WHO definitions of blindness and visual impairment according to visual acuity were used as criteria for classification of visual blindness and visual impairment. Results: The prevalence of bilateral cataract blindness (cataract causing visual acuity of less than 3/60 in the better eye) for people of 50 years and above was 4.1% (95% CI: 2.96 to 5.24%) with cataract accounting for 41.2% of all the blindness in this age group. Prevalence of cataract blindness was higher in females than in males (5.0% versus 3.6%) About 80% of the cataract blindness occurs in people of 70 years and above. The cataract surgical coverage for eyes was 4.5%; cataract surgical coverage for couching was 18.2%. The major barriers to the uptake of cataract surgical services were lack of awareness of eye care services in nearby district (71.0%), the imagined high cost of the services (17.9%) the perception of women that their health problems are not of immediate importance (7.1%). Conclusion:At the time of study about 2000 person required immediate cataract surgery in the area. With an estimated incidence of 400 new cases per year, there is a need to set up cataract surgical services in the Ughelli North local government area. Special attention should be given to reduction of cataract blindness in females