Optical (Partial Optical Coherence Interferometry) (AL-Scan) versus Ultrasound Biometry (A-Scan) for IOL Power Calculation: A Comparative Study
Journal Title: Ophthalmology and Allied Sciences - Year 2018, Vol 4, Issue 1
Abstract
Context: The refractive power of the human eye depends on the power of the cornea and the lens, the position of the lens, and the length of the eye. Accurate assessment of these variables is essential in achieving optimal postoperative refractive results. Aims: To compare the accuracy of IOL power calculation by measuring the axial length with Optical (Partial Optical Coherence Interferometry AL-Scan) biometry and Ultrasound biometry. Settings and Design: It was a prospective observational study done at Medivision eye and Health Care centre. Methods and Material: The study group was 200 patients, who underwent Phaco-emulsification. The SRK-T formula was used to calculate the IOL power in all patients. Auto-keratometry performed with the optical scan was used in all patients. Statistical Analysis: Mean (SD) and frequency (percentage) was used to describe summary data. Paired T test was performed to explore statistically significant difference between two measurements. Chi-square was used to assess the difference between categorical variables. Results: Out of 200 patients 83 (41.5%) were female and 117 (58.5%) were male. Mean Age of the study population was 62.30±7.66 years and the range 33 to 81. The mean difference between axial lengths measured by the 2 modalities was 0.1274±0.1733 mm with AL Scan measuring higher than US Biometry (Paired T- Test p < 0.05). The residual error was Zero in 75 (37.5%) eyes in the AL-scan group and 59 (29.5%) eyes in the A-scan group. When analyzed at 95% confidence for the difference at zero error in pre-operative prediction versus post-operative acceptance of IOL power, the predictions did not differ between both the modalities. Conclusion: The AL-scan is on average a closer predictor than A-scan of the final spherical equivalent. AL-scan may offer a slight advantage because of the easier and quicker operation compared with the A-scan.
Authors and Affiliations
Rajitha Kondam
Keywords
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- EP ID EP550566
- DOI 10.21088/oas.2454.7816.4118.5
- Views 87
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