Introduction: Corneal thickness is measured by pachymetry and has important clinical implications on corneal health. The mean central corneal thickness in healthy human eyes is about 545 micrometres in whites and about 530 micrometers in blacks.
Central corneal thickness is of clinical importance because it affects intraocular pressure (IOP) measurements by applanation tonometry in the assessment of glaucoma. However, no study on CCT has ever been done before in Uganda.
General objective: To characterize the central corneal thickness in the black population seen at Ruharo Eye Centre.
Specific objectives: To establish central corneal thickness in the black population seen at Ruharo Eye Centre and relate it to intraocular pressure (lOP), refractive errors, and some socio-demographic characteristics, specifically age, sex, and ethnicity.
Methodology: A hospital-based cross-sectional non-interventional study, which assessed central corneal thickness of Ugandans of all age groups, was conducted at Ruharo Eye Centre. Subjects with normal corneas were consecutively recruited and data were collected using a questionnaire.
Results: A total of 360 patients were seen at Ruharo Eye Centre in the months of May to August 2007. There were 196 (54.4%) males and 164 (45.6%) Females. 46 (12.8%) were children and 314 (87.2%) were adults. CCT was taken and analysed according to the age groups, and was found to decrease with increasing age in adulthood. The mean CCT was 522.6 µm. Male subjects had significantly thicker
corneas (526 µm) than females (518.4 µm). Thick corneas were significantly related to increase in lOP.
Bantu people had thicker corneas as compared to other ethnic groups with the highest mean CCT of 524.9 µm. Nilotics had 512 µm, while Hamites bad the thinnest cornea measuring 502.6 µm.
There was no relationship betweeen CCT and refractive errors. Emmetropics were 67%. myopes were 12%, and hyperopes were 11%. In 10% of the patients no refraction was done because these were children who could not cooperate fully.
Conclusion: The purpose of this study was to characterize the CCT in a black Ugandan population of all age groups. There was a correlation between CCT and gender and ethnicity. CCT significantly increased with the increasing lOP. This observation supports the hypothesis that when measured by an applanation tonometer, lOP is overestimated in eyes with thick corneas and underestimated in eyes with thin corneas. It is recommended that CCT be measured along with IOP in all glaucoma suspects.
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