AIM: To compare the agreement between the ARK Biometer Combo and OA 2000 in patients wearing orthokeratology lenses.

METHODS: A prospective study. A total of 148 patients(148 eyes)who were wearing orthokeratology lenses and returned for follow-up at the Shanghai Eye Disease Prevention and Treatment Center from August to September 2024 were included. Biometric measurements were performed using both the ARK Biometer Combo and OA 2000. Parameters including axial length(AL), corneal central thickness(CCT), anterior chamber depth(ACD), lens thickness(LT), corneal curvature(Kf and Ks), astigmatism(AST), white-to-white corneal diameter(WTW)and pupil diameter(PD)were obtained. Differences in measurement parameters between the two biometers were compared, and agreement was assessed.

RESULTS: There were no statistically significant differences in the measurements of Kf, Ks and AST between the two biometers(P>0.05). Statistically significant differences were found in the measurements of AL, CCT, ACD, LT, WTW and PD(t=2.559, P=0.012; t=16.771, P<0.0001; t=4.749, P<0.0001; t=-15.212, P<0.0001; t=-14.915, P<0.0001; t=-2.402, P=0.018). ICC ranged from 0.615 to 0.999. Bland-Altman analysis showed that the maximum absolute values of the 95% limits of agreement(LoA)of AL, CCT, ACD, LT, Kf, Ks, AST, WTW and PD were 0.07 mm, 35.07 μm, 0.07 mm, 0.12 mm, 0.66 D, 1.14 D, 1.00 D, 0.76 mm, and 0.98 mm, respectively.

CONCLUSION: In orthokeratology patients, the ARK Biometer Combo and OA 2000 showed good agreement in measuring AL, CCT, ACD, Kf and LT, and can be used interchangeably.