Comparison Of Central Corneal Thickness Measurements Using Optical Coherence Tomography And Scheimpflug Tomography In Eyes With Corneal Scars

Published 2026 - 44th Congress of the ESCRS

Reference: PP19.018 | Type: Free paper | DOI: 10.82333/y22n-vv95

Authors: Dr Caglar Bektas* ¹ , Dr Aslınur Ezber ¹

¹Ophthalmology,Çanakkale Onsekiz Mart University Faculty of Medicine,Çanakkale,Türkiye

Purpose

To evaluate central corneal thickness (CCT) agreement between optical coherence tomography (OCT) and Scheimpflug tomography in scarred corneas, and identify predictors of inter-device discrepancy.

Setting

A single-center, tertiary care university hospital.

Methods

This retrospective study included 38 eyes with central corneal scars and 35 healthy controls. CCT was measured via OCT and Scheimpflug tomography. A >20 µm inter-device difference (OCT minus Scheimpflug ) was defined as clinically significant. We analyzed best corrected visual acuity (BCVA), OCT CCT, Scheimpflug CCT, thinnest corneal thickness (TCT), and relative pachymetry. Central 1-mm/3-mm corneal transparency and scar depth-to-thickness ratio were objectively quantified from Scheimpflug images using MATLAB (MathWorks).

Results

Mean age was comparable between scar (60.5 ± 17.5 years) and control (58.7 ± 18.5) groups (p>0.05). Mean inter-device difference was significantly higher in scarred eyes (22.26 ± 52.11 µm) than in controls (-2.14 ± 15.24 µm) (p=0.001). In the scar group, objective corneal transparency and scar ratio did not correlate with the measurement discrepancy. Between eyes with ≤20 µm (n=17) and >20 µm (n=21) discrepancy, no significant difference existed in BCVA (p=0.095) and OCT CCT (p=0.130). However, Scheimpflug CCT (p=0.007), TCT (p=0.010), and relative pachymetry (p=0.007) differed significantly, indicating that thinner corneas according to Scheimpflug are associated with greater inter-device mismatch.

Conclusions

Corneal scars significantly disrupt the agreement between OCT and Scheimpflug CCT measurements. This discrepancy is primarily driven by Scheimpflug-measured corneal thinning rather than the objective corneal transparency. Therefore, caution is advised when using these devices interchangeably in scarred corneas, particularly in cases with thin CCT according to Scheimpflug tomography.