Purpose To assess the repeatability of a new swept-source optical coherence tomography (SS-OCT) biometer (IOLMaster 700) and evaluate the agreement with an optical low-coherence reflectometry (OLCR) biometer (Lenstar 900) in cataractous eyes. Setting Tertiary eyecare facility. Design Prospective evaluation of a diagnostic test. Methods Eyes of patients had 3 consecutive scans acquired by the same operator. The repeatability of measurements was assessed using the within-subject standard deviation and coefficient of variation (CoV). Agreement between the mean measurements of each machine was evaluated. Results The study comprised 100 eyes of 100 patients. The median lens thickness and axial length (AL) measurements were significantly greater ( P  < .001) with SS-OCT (4.29 mm and 23.5 mm, respectively, versus 4.25 mm and 23.4 mm, respectively); anterior chamber depth (ACD) was greater with OLCR (2.72 mm versus 2.70 mm, respectively) ( P  < .001). The within-subject standard deviation and CoV of the AL (0.01 and 0.05, respectively) and the ACD (0.04 and 1.22, respectively) measurements showed lower variability with SS-OCT (0.05 and 0.21, respectively, for AL; 0.06 and 1.99, respectively, for ACD) than with OLCR. Good agreement was seen for anterior segment measurements between the 2 devices. The 95% limits of agreement of most parameters fell within the test–retest variability of the parameters. The SS-OCT biometer also showed better penetration in dense posterior subcapsular cataracts, measuring AL successfully in 96% of cases. Conclusions The new SS-OCT biometer showed good repeatability and agreement with the OLCR biometer. The SS-OCT biometer measured the AL with fewer dropouts compared with the OLCR even in dense cataracts. Financial Disclosure None of the authors has a financial or proprietary interest in any material or method mentioned.