Vol 17, Issue 2, 2024 Online - 2455-3891 Print - 0974-2441 A COMPARATIVE STUDY OF OPTICAL BIOMETRY AND IMMERSION A-SCAN ULTRASOUND IN PATIENTS UNDERGOING PHACOEMULSIFICATION WITH FOLDABLE INTRAOCULAR LENS IMPLANTATION SURGERY SUMIT DILIP DONGARE , AJIT KAMALAKAR JOSHI , NISARG PACHAURI* Department of Ophthalmology, Bharati Vidyapeeth (Deemed to be) University Medical College and Hospital, Sangli, Maharashtra, India. *Corresponding author: Nisarg Pachauri; Email: neosurge06@gmail.com Methods: The study was carried out in the Ophthalmology Department of Bharati Vidyapeeth (Demeed to be University) Medical College and Hospital Sangli, from November 2019 to April 2021. A total of 60 eyes of 60 patients were included in the study. All patients underwent both techniques of biometry, namely, optical and immersion A-scan biometry. Mean AL was calculated and compared between the two methods. Then patients were divided into two groups: Group A and Group B; randomization was done on the basis of odd and even numbers. All patients underwent phacoemulsification with foldable IOL implantation surgery and followed up on 1 week and then on 1 month. All patients were operated by single surgeon and a single technique was used. Actual post-operative refractive error, that is, mean of spherical equivalent was compared between two groups on 1-month follow-up. Results: At 1-month follow-up, actual post-operative refractive error was obtained after calculating spherical equivalent for all the patients and we found that, the mean of actual post-operative refractive error for Group A was higher (−0.371±0.24 D) compared to Group B (−0.264±0.16 D) and the comparison was statistically significant (p=0.049). Conclusion: Optical biometry is slightly more accurate than ultrasound biometry, in terms of accuracy and reproducibility of the IOL power calculation, but ultrasound biometry is adequate in case optical biometry is unavailable. Keywords: Cataract, Phacoemulsification, Optical biometry, Immersion A-scan. INTRODUCTION Cataract is the major cause of blindness in the world and also it is the most prevalent ocular disease [1]. In India, cataract is the cause of bilateral blindness in 50–80% of bilaterally blind patients. Among all types of cataracts, senile cataract is seen most commonly in clinical practice. Other secondary causes include hereditary factors, inflammation, metabolic syndromes, exposure to radiation, nutritional disorders, and trauma. [2]. Cataract extraction and intraocular lens (IOL) implantation is one of the most commonly performed surgical procedures in ophthalmology. The modern technique of cataract extraction is small incision phacoemulsification with foldable lens implantation [3]. It is minimally invasive, rehabilitation is quick, and has a low complication rate. In recent days, cataract surgery not only focuses on visual rehabilitation but is now considered a form of refractive surgery. The success of cataract surgery is determined by post-operative refractive outcomes and patient satisfaction [4]. In the last few decades, revolutionary technological developments have occurred in IOL designs, ocular biometry techniques, phacoemulsification procedures, and IOL calculation formulae [5]. To achieve the desired post-operative refraction, accurate calculation of IOL power is most important. This depends on several factors including axial length (AL) measurement, keratometry, anterior chamber (AC) depth, IOL calculation formula, and quality of IOL [6]. The most important step for accurate calculation of IOL power is the pre-operative measurement of ocular AL which is probably the element with the largest potential for error. Ultrasound biometry reported that 54% of the errors in predicted refraction after IOL implantation can be due to inaccurate AL measurements [7]. AL measurement and IOL power calculation can be done by conventional ultrasound biometry and optical biometry. A-scan ultrasound biometry calculates AL from the time taken for ultrasound waves to reflect back to its receiver from the internal limiting membrane and it includes contact and immersion methods. It requires the use of topical anesthetic and previously done keratometry on a manual or automatic mode [8]. Optical biometry also known as partial coherence interferometry (PCI) is a fast non-contact method which is more precise and accurate than A-scan biometry as it is based on the reflection of interference signal of retinal pigment epithelium (RPE) [9]. Hence, to make the optical biometry results comparable with previous ultrasound measures, a conversion factor has been incorporated into the instrument software. The built in software in this device provides more accurate IOL power calculation and multiple choices for IOL formulae [10]. Modern cataract surgery is characterized by obtaining precise post- operative target refraction as the number of patients opting for premium IOLs is increasing and patient expectations to get independence from glasses are very high [10]. © 2024 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (http://creativecommons.org/ licenses/by/4.0/) DOI: http://dx.doi.org/10.22159/ajpcr.2024v17i2.50443. Journal homepage: https://innovareacademics.in/journals/index.php/ajpcr Research Article Objectives: The objective of this study was to compare optical biometry with immersion A-scan ultrasound biometry in terms of axial length (AL) and post-operative refractive error by assessing 1-month post-operative refraction in patients undergoing phacoemulsification with foldable intraocular lens (IOL) implantation surgery. Received: 2 December 2023, Revised and Accepted: 24 January 2024 ABSTRACT