Optimizing lens constants specifically for short eyes: Is it essential?

• Main Authors: Ankur K Shrivastava, Swatishree Nayak, Ashish Mahobia, Mary Anto, Rajaram Kacher, Ajay Kumar
• Format: Article
• Language: English
• Published: Wolters Kluwer Medknow Publications 2021-01-01
• Series: Indian Journal of Ophthalmology
• Subjects: formulae; intraocular lens power; lens constant optimization; phacoemulsification; short eyes
• Online Access: http://www.ijo.in/article.asp?issn=0301-4738;year=2021;volume=69;issue=9;spage=2293;epage=2297;aulast=Shrivastava
• ISSN: 0301-4738; 1998-3689

Purpose: Optimization of lens constants is a critically important step that improves refractive outcomes significantly. Whether lens constants optimized for the entire range of axial length would perform equally well in short eyes is still a matter of debate. The aim of this study was to analyze whether lens constants need to be optimized specifically for short eyes. Methods: This retrospective observational study was conducted at a tertiary care hospital in Central India. Eighty-six eyes of eighty-six patients were included. Optical biometry with IOLMaster 500 was done in all cases and lens constants were optimized using built-in software. Barrett Universal II, Haigis, Hill-RBF, Hoffer Q, Holladay 1, and SRK/T formulae were compared using optimized constants. Mean absolute error, median absolute error (MedAE), and percentage of eyes within ±0.25, ±0.50, ±1.00, and ±2.00 diopter of the predicted refraction, of each formula were analyzed using manufacturer's, ULIB, and optimized lens constants. MedAE was compared across various constants used by Wilcoxon signed-rank test and among optimized constants by Friedman's test. Cochran's Q test compared the percentage of eyes within ± 0.25, ±0.50, ±1.00, and ± 2.00 diopter of the predicted refraction. A value of P < 0.05 was considered statistically significant. Results: Optimized constant of Haigis had significantly lower MedAE (P < 0.00001) as compared to manufacturers. However, there was no statistically significant difference between ULIB and optimized constants. Postoptimization, there was no statistically significant difference among all formulae. Conclusion: Optimizing lens constants specifically for short eyes gives no added advantage over those optimized for the entire range of axial length.