Correlation of ocular biometry parameters with corneal astigmatism in cataract surgery subjects – A swept-source optical coherence tomography study

Objectives: To scrutinise ocular biometry parameters and determine their correlation, with special reference to corneal astigmatism in cataract surgery subjects by swept-source optical coherence tomography (OCT) in a tertiary eye care center. Material and Methods: A prospective hospital-based cross-sectional study was conducted on cataract surgery candidates aged ≥21 years during a 10-month study period. Swept-source OCT was used for ophthalmic biometry (IOL Master 700, Carl Zeiss Meditec AG, Jena, Germany, 2015). Axial length (AL), anterior chamber depth (ACD), lens thickness (LT), white-to-white measurement (WTW), and keratometry (K) (K1-flat K and K2-steep K) are parameters examined. The difference between K2 and K1 readings was used to determine corneal astigmatism. Results: 500 eyes of 250 patients were analysed. Subjects consisted of 44.4% males (n = 111) and 55.6% females (n = 139). The average age of patients was 63.42 ± 9.572 years (mean). Corneal astigmatism ranged from 0 to 4.27 D; with a mean of 0.920 ± 0.669 D. Astigmatism was absent in 1.6% (n = 8), 26% of eyes had astigmatism with-the-rule (WTR) (n = 130), 55.6% had astigmatism against-the-rule (ATR) (n = 278) and 16.8% had oblique astigmatism (n = 84). Astigmatism <1.00 D was found in 66.4% (n = 332), and astigmatism ≥1.00 D was found in 33.6% (n = 168). The mean AL, ACD, LT, and WTW of the study population were 22.97 ± 0.988 mm, 3.17 ± 0.40 mm, 4.29 ± 0.50 mm, and 11.90 ± 0.40 mm, respectively. Our study reveals several notable positive correlations. Notably, age exhibits positive correlations with LT, K2, and ΔK. AL demonstrates positive associations with ACD, WTW, and ΔK. Conclusion: This study provides an in-depth analysis of the biometry parameters of subjects from the Indian subcontinent. A normative database is a prerequisite for any interventional procedure, and this study intends to serve that purpose. We also report that about two-thirds of subjects undergoing cataract operation had corneal astigmatism <1.0 D and do not require toric lens implantation.