Ocular Axial Length and Keratometry Readings of Normal Eyes in Southern Nigeria
Aim: To provide average axial length and keratometry readings in healthy eyes of people in Rivers and surrounding states in southern Nigeria. This may guide the purchase of intraocular lens in the study area.
Materials and methods: Four hundred consecutive patients with 800 non-cataractous eyes attending the eye clinic of the University of Port Harcourt Teaching Hospital eye clinic over a period of 2 years (January 2006 to December 2007), had amplitude scan ultrasonography.
The instrument used was the Auto Axial length Biometer, model AL-010 by Tomey. Keratometry readings were carried out within the same period using the Acutus auto-refractor model 5015-3212 by Carl Zeiss Meditec AG. All results were fed into and analysed using the Tomey biometer.
Results: The average A-Scan was 23.86 mm (SD±1.2) for male subjects and 23.27mm (SD±1.18) for females. The overall range for axial length among the cohort was 21.14mm to 28.91mm. Average axial length for both sexes is 23.57mm (SD±1.19). The mean for male subjects was 42.95D (SD±1.30) while for females it was 41.90D (SD±1.55). The
keratometry readings ranged between 41D and 45D. The overall mean keratometry reading was 42.43D. Conclusion: The average calculated IOL power was 22.61D for female and 20.11D for male subjects, using the SRKII formula. The overall average of 21.34D makes it easier
for supplies to be purchased in bulk for use in remote places.
Keywords: A-scan, keratometry, IOL power, noncataractous eyes, Nigeria