The Effect of Cycloplegia on the IOLMaster 700 and OA-2000 Biometry in Cataract Patients

Objective: To evaluate the effect of cycloplegiaon new ocular biometry measurements using the IOLMaster 700 and OA-2000 biometers and assess the differences and agreements between the two devices. Methods: In this prospective, comparative, observational study of ocular measurements on 133 cataracts, measurements of axial length (AL), mean keratometry (Km), anterior chamber depth (ACD), lens thickness (LT), central corneal thickness (CCT) and white-to-white (WTW) were performed by a single operator using the two devices before and after pupil dilation. The measurement order of the two devices was determined according to the random number table. A paired t-test was applied to evaluate the differences with and without cycloplegia on each device. Bland-Altman plots and a paired t-test were used to evaluate the agreements and differences between the two devices with and without cycloplegia. Results: Cycloplegia had no significant effect on AL or Km. However, ACD and CCT significantly increased by 0.06 mm and 2-3 μm post-cycloplegia on both devices. The IOLMaster 700 LT measurements significantly decreased by 0.01 mm (t=-6.26, P<0.001) and WTW increased by 0.12 mm (t=7.06, P<0.001) after pupil dilation. ACD measurements with OA-2000 were higher by 0.04 mm (t=-13.36, P<0.001; t=-15.08, P<0.001) and LT by 0.07 mm (t=-11.11, P<0.001; t=-8.42, P<0.001), which were statistically significant, compared to the IOLMaster 700 before and after pupil dilation, while CCT was smaller by 17 μm (t=30.55, P<0.001; t=28.80, P<0.001). The 95% limits of agreement in both devices were -0.79 to 0.81 mm pre-cycloplegia and -0.44 to 0.81 mm post-cycloplegia. All measurements had good agreements between the two devices, except for WTW. Conclusions: Cycloplegia affects ACD and CCT, but not AL or Km measurements. LT decreased and WTW increased on the IOLMaster 700 after pupil dilation. Generally, there is good agreement between the IOLMaster 700 and OA-2000, except for WTW. Thus, either can be used for the preoperative examination of cataracts. Key words: IOLMaster 700; OA-2000; cataract; cycloplegia