Central Corneal Thickness and Intraocular Pressure of Adult Nigerians: An Assessment of Zaria Community

Glaucoma is the commonest cause of irreversible blindness globally and intraocular pressure is the only known risk factor that can be therapeutically manipulated to change the course of the disease.1 Central corneal thickness (CCT) is known to affect the accuracy of intraocular pressure (IOP) measurements by applanation tonometry.2 A thicker cornea requires greater force to flatten and, conversely, a thinner cornea is more easily flattened. Data on this important parameter is scanty in northern Nigeria. The aim and objective of this study was to determine the mean CCT and IOP and relate CCT to Age and IOP.

It was a cross sectional study of the right eyes of two hundred and two suitable consecutive participants in an eye screening camp. Their IOP was measured using Perkins Applanation Tonometer and the CCT was assessed using an ultrasound Pachymeter (Sonomed Pac Scan 300AP+).These were done for both eyes at the same sitting by the same examiner. The data was analysed using Analyse-it for Excel soft ware.

There were 50 males and 152 females. M:F 1:3 and age range was 18-80 years with mean of 46.2 years ± 15 years. The mean CCT was 526.90mm ±SD 35.3.The mean in those who have glaucoma/glaucoma suspects was 523.10mm ±SD 41.3.The mean IOP was 16.8 ± 5.1mmHg. Age/CCT Pearson's correlation: r = -0.20 t= -3.97 p <0.0001. The CCT/IOP Pearson's correlation r=0.16, p=0.0206.T Conclusion: The mean CCT of 526.90mm for non-glaucomatous eyes in this study is thinner than but comparable to similar population of African Americans (528.50mm) and black population of Barbados Eye Study(529.80mm) .Similarly those of Egyptians(530.10mm) and Sudanese (530.20µm) were thicker. The value for white population of Barbados Eye Study was the thickest (545.20mm).There was a negative correlation between Age and CCT but a positive correlation between CCT and IOP.