Purpose  To evaluate the intra-observer repeatability and validity of the biometric measurement by a newly developed auxiliary apparatus of A-scan ultrasound.

Methods  Age-related cataract patients awaiting for cataract surgery were consecutively enrolled for preoperative A-scan biometric measurement. The applanation A-scan was performed by two experienced nurses with one using conventional handheld method and the other using the new method with the auxiliary desktop apparatus. Two consecutive measurements were carried out for each method. The 95% limit of agreement (95% LoA) and Bland-Altman plot were used to assess and compared the inter-session measurement repeatability between two methods.  

Results  Dataof 75 eyes of 75 consecutive patients were available for analysis. The mean age of participants was 74.3±7.4 years, 40.0% were men. Compared with the conventional handheld method, the desktop method presented smaller standard deviation and coefficient of variance for both measurement sessions. For inter-session repeatability, the desktop method had narrower 95% LoA range than the handheld method for all the biometry parameters. The axial length obtained by desktop method was significant longer than that from the handheld method (23.32 mm versus 23.14 mm, P<0.01).

Conclusions  The better intra-observer repeatability and more accurate AL measurement compared with the conventional handheld method make this newly developed auxiliary device an ideal option for preoperative biometric measurement of cataract surgery.