IOL master and A-scan biometry in axial length and intraocular lens power measurements

Abstract

Purpose The purpose of this paper is to evaluate differences between IOL master and A-scan regarding axial length (AXL) and predicted IOL power in different types of cataract. Patients and methods Forty eyes of 40 patients underwent examination by IOL master and A-scan, where average K-reading, AXL and predicted IOL power were compared. Results Forty eyes of 40 patients were included. The mean AXL measured by IOL master was higher (26.18±2.92 mm) than that with A-scan (26.02±2.99 mm) with a mean difference of 0.2±0.44 mm (P=0.07). The mean predicted IOL power was 11.61±8.33 D with IOL master versus 12.01±8.23 D with A-scan (P=0.03). However, no statistically significant difference was found regarding average K-readings and predicted postoperative refraction (P=0.4 and 0.7, respectively). Bland–Altman plots showed almost perfect agreement between both methods regarding AXL and predicted IOL power. Further subgroup analysis revealed a statistically significant difference in AXL between both devices only in nuclear cataract with no significant difference in cases with complicated cataract to myopia or silicone oil (P=0.013, 0.2 and 0.1, respectively). No statistically significant difference was found between the three groups regarding the calculated IOL power (P=0.34, 0.13 and 0.15, respectively). Bland–Altman analysis showed almost perfect agreement for the mean difference of AXL and IOL power in the three subgroups. Conclusion There is no significant difference between IOL master and A-scan biometry, with the noncontact IOL master being preferred by patients; however, there exists certain situations where A-scan is still mandatory.

Keywords

• a-scan
• average keratometry-reading
• axial length
• iol master
• predicted intraocular lens power