COMPARATIVE STUDY OF MANUAL VERSUS AUTOMATED BIOMETRY ON REFRACTIVE OUTCOME OF CATARACT SURGERY
Journal Title: Journal of Evolution of Medical and Dental Sciences - Year 2018, Vol 7, Issue 45
Abstract
BACKGROUND Intraocular Lens (IOL) power calculation is the most important step to achieve best refractive outcome in cataract surgery. Various studies had revealed that about 54% of the error in predicted refraction occurred due to inaccuracy in axial length measurement alone. Therefore, axial length measurement is the most important step to minimise these errors. The aim of this study was to compare IOL power calculation using a manual method (Applanation ultrasound A-Scan and Keratometry) with the automated method (Optical biometry). MATERIALS AND METHODS It was a prospective, comparative study. In this study, 200 eyes of 196 patients were analysed in the Department of Ophthalmology. Each eye underwent measurement by both methods, with manual method (Applanation Ultrasound A-Scan and manual Keratometer) and with automated optical biometry. Axial length and Keratometric readings were obtained and IOL power calculation was done by both the methods. Patient underwent clear corneal phacoemulsification cataract surgery within the IOL implantation in all the cases, then postoperative autorefraction was noted in all cases in follow-ups. RESULTS The Mean Axial Length calculated by optical A scan was 23.02±1.00 mm and by ultrasound A scan was 22.93±1.03 mm. The mean difference in axial length between optical system and Ultrasound A scan was 0.087±0.039 mm, which is statistically not significant (p value 0.19). However, differences in axial length measurement were more when compared, for short eyes, by two devices. After analysis of Bland-Altman plot. All differences were within two standard deviations (95% confidence level) from mean differences (0.0869±0.038 mm, i.e. between 0.0096 mm and 0.1641 mm). The regression line between the two methods, Pearson’s correlation coefficient ‘r’ is 0.999, which evaluates excellent agreement of axial length measurement between two methods. The differences in mean IOL power between automated method and manual method was 0.43±0.38 D, which was statistically and clinically insignificant (p value 0.09). CONCLUSION To measure axial length and IOL power, optical biometry is very precise and interchangeable with ultrasound method. Optical biometry in short eyes gives better result in axial length measurement as compared to ultrasound A-scan.
Authors and Affiliations
Santosh Singh Patel, Rajesh Kumar Sahu, A. K. Chandrakar, M. L. Garg, Reshu Malhotra
Keywords
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- EP ID EP549346
- DOI 10.14260/jemds/2018/1089
- Views 66
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