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Applanation biometry in Ilorin, Nigeria
Abstract
Background: Extracapsular cataract surgery with posterior chamber intraocular lens implant (ECCE-IOL) is still routinely done without biometry in most developing nations for various reasons but mainly due to non availability of the required equipment.
Aim
• To evaluate the accuracy of the choice of intraocular lens in cataract surgery with recently acquired biometry equipment
• To carry out a comparative study of refractive outcome of cataract surgery with and without biometry in a tertiary teaching hospital in Ilorin, Kwara State, Nigeria
Patients and method: This is a non randomized prospective study of the visual outcome of all cases of ECCE-IOL surgery done by the same group of surgeons before and after the availability of biometry. Biometry was by A scan applanation contact technique using the SRK-2 formula. Only patients who did not have any surgical complication were included in the study.
Results: For patients who had surgery without biometry, average keratometry reading (K1) was 43.38D. Minimum and maximum values were 33.30D and 47.25D respectively, while average (K2) value for surgery with biometry was 43.47D, with a minimum of 36.10D and maximum of 49.13D. The average axial length was 22.87mm with standard deviation of ± 2.4 and standard error of 0.23. Evaluation of the accuracy of the IOL power used showed that 56%, 75%, 95% and 99% of the patients were within 1D, 2D, 3D and 4D of predicted value respectively. Visual outcome at discharge and at two months without refraction was better in the group without biometry (P value < 0.05). The visual outcome at two months with refraction was statistically the same but the series with biometry met the WHO guideline of 90% good outcome as compared to 83.8% in the group without biometry.
Conclusion: The main reasons for the seeming lack of benefit from biometry include wrong IOL power calculation, and non availability of calculated power in the range below 17D and above 22D. We recommend local production of IOL or central purchasing of the not commonly used IOL powers. Users of newly acquired equipment must be trained while trained biometrists could be assigned to routinely carry out biometry.
Nigerian Journal of Ophthalmology Vol. 14(1) 2006: 18-21
Aim
• To evaluate the accuracy of the choice of intraocular lens in cataract surgery with recently acquired biometry equipment
• To carry out a comparative study of refractive outcome of cataract surgery with and without biometry in a tertiary teaching hospital in Ilorin, Kwara State, Nigeria
Patients and method: This is a non randomized prospective study of the visual outcome of all cases of ECCE-IOL surgery done by the same group of surgeons before and after the availability of biometry. Biometry was by A scan applanation contact technique using the SRK-2 formula. Only patients who did not have any surgical complication were included in the study.
Results: For patients who had surgery without biometry, average keratometry reading (K1) was 43.38D. Minimum and maximum values were 33.30D and 47.25D respectively, while average (K2) value for surgery with biometry was 43.47D, with a minimum of 36.10D and maximum of 49.13D. The average axial length was 22.87mm with standard deviation of ± 2.4 and standard error of 0.23. Evaluation of the accuracy of the IOL power used showed that 56%, 75%, 95% and 99% of the patients were within 1D, 2D, 3D and 4D of predicted value respectively. Visual outcome at discharge and at two months without refraction was better in the group without biometry (P value < 0.05). The visual outcome at two months with refraction was statistically the same but the series with biometry met the WHO guideline of 90% good outcome as compared to 83.8% in the group without biometry.
Conclusion: The main reasons for the seeming lack of benefit from biometry include wrong IOL power calculation, and non availability of calculated power in the range below 17D and above 22D. We recommend local production of IOL or central purchasing of the not commonly used IOL powers. Users of newly acquired equipment must be trained while trained biometrists could be assigned to routinely carry out biometry.
Nigerian Journal of Ophthalmology Vol. 14(1) 2006: 18-21
