An algorithm to convert optical coherence tomography central corneal thickness values to ultrasound central corneal thickness values and its corresponding correction factor

Abstract

Objective: To develop an algorithm to convert OCT CCT values to USS CCT values and apply the corresponding correction factor in managing patients.
Design: A cross sectional comparative study carried in 100 eyes of 50 patients attending Rachel Eye Center in Abuja from January to March 2021. CCT was measured using the Pachscan ultrasound and the Optovue machine utilised for the OCT technique. Data was analysed using SPSS version 20 using the linear regression analysis. The linear regression formula was then applied to develop an algorithm to convert OCT CCT values to USS CCT values and apply the corresponding correction factor.
Settings: The study was conducted in a private eye hospital, Rachel Eye Center, Abuja, Nigeria.
Subjects or Participants: 100 eyes of 50 consecutive patients attending Rachel Eye Center in Abuja from January to March 2021.
Intervention: The linear regression formula was developed and then applied to develop an algorithm to convert OCT CCT values to preset USS CCT values and it’s the corresponding correction factor.
Main outcome measures: The linear regression formula OCT=-2.184+ (0.955 x USS) p<0.001
Results: A linear regression formula OCT=-2.184+ (0.955 x USS) p<0.001 was derived. The linear regression formula was then imputed into Microsoft excel to derive the OCT CCT values of preset USS CCT values alongside their corresponding correction factors, which was obtained from the modified Ehler’s scale.
Conclusions: The algorithm enables us to convert OCT CCT values to USS CCT values and apply the corresponding correction factor in managing our patients.