Posters

Repeatability and agreement of biometric measurements using spectral domain anterior segment optical coherence tomography and scheimpflug tomography in keratoconus

Poster Details

First Author: M.Ziaei NEW ZEALAND

Co Author(s):    Y. Li   A. Gokul   C. McGhee   M. Ziaei           

Abstract Details

Purpose:

To compare the repeatability and agreement in biometric measurements using Spectral Domain Anterior Segment OCT (AS-OCT, REVO NX, Optopol) and Scheimpflug tomography (Pentacam-AXL, Oculus) in patients with keratoconus.

Setting:

University of Auckland Cornea and External Eye Disease Tertiary Service.

Methods:

This prospective case series enrolled patients with keratoconus attending the corneal disease clinic from January 2019 to August 2019. Eyes with corneal oedema, scarring, prior ocular surgery other than CXL, or trauma were excluded. Axial length (AL), anterior chamber depth (ACD), central corneal thickness (CCT), and thinnest corneal thickness (TCT) were measured three times using each device. The eyes were analysed in groups: no prior crosslinking or contact lens wear (Group A), prior crosslinking (Group B), and prior contact lens wear (Group C). Repeatability of measurements was assessed using the intraclass correlation coefficient (ICC). Agreement was analysed using Bland-Altman plots.

Results:

This study comprised of 157 subjects. In Group A (n=95 eyes), Group B (n=86 eyes), and Group C (n=33 eyes), ICC was higher than 0.90 for all examined parameters, except for ACD readings in Group A with the REVO NX (ICC=0.83). Differences in ACD, TCT, and CCT were statistically significant between the two devices for Groups A, B and C (p<0.05). AL measurements differed significantly between Groups A and B (p<0.05) but not in Group C (p=0.18). Repeatability did not vary significantly between Groups A, B, or C in any parameter with both devices (p<0.05).

Conclusions:

Both the REVO NX AS-OCT and Pentacam-AXL Scheimpflug system demonstrated good repeatability but poor agreement across AL, ACD, CCT and TCT measurements. Scheimpflug imaging demonstrated better repeatability across all biometric parameters. A history of prior crosslinking or contact lens wear did not affect the repeatability in biometric measurements on either device. The two devices should not be used interchangeably in the assessment, surveillance, or for IOL calculations in patients with keratoconus.

Financial Disclosure:

None