Evaluation of the Cornea by Anterior Segment Optical Coherence Tomography in Diseases of the Cornea.

AIM

The aim of the study was to determine any new findings provided by anterior segment optical coherence tomography (AS-OCT) in different corneal diseases diagnosed by slit lamp examination (SLE).

METHODS

This cross-sectional, observational, hospital-based study was conducted at a tertiary care centre in Western Maharashtra from September 2022 to June 2024, and it included 93 eyes of 93 patients with isolated corneal diseases. A detailed SLE of the anterior segment was done to assess corneal pathology, corneal thickness, corneal structural integrity, presence of corneal opacities, corneal vascularization, presence of other abnormalities like corneal degeneration, corneal foreign bodies, Kayser-Fleischer (KF) ring, ocular surface squamous neoplasia (OSSN). All patients underwent AS-OCT with imaging protocols tailored to each corneal condition, including assessment of focal thinning in Keratoconus patients, graft-host junction integrity in post-keratoplasty cases, Descemet's membrane integrity in post-cataract surgery patients, localization and depth of invasion of corneal foreign bodies, detection of KF rings in Wilson's disease cases, and identifying and assessing extent of corneal dystrophies, corneal degenerations, and OSSN. AS-OCT findings were compared with SLE results to identify any additional information provided by AS-OCT over SLE in the study population. For statistical analysis, data was entered into Microsoft Excel (Microsoft Corporation, Redmond, Washington, United States) and analysed using IBM SPSS Statistics for Windows, Version 26.0 (Released 2019; IBM Corp; Armonk, New York, United States). Inter-rater agreements between SLE and AS-OCT were evaluated by Cohen's Kappa by using IBM SPSS Statistics for Windows, Version 26.0.

RESULTS

AS-OCT enabled additional diagnosis of three (15.8%) more cases of keratoconus, which were declared normal on SLE. AS-OCT identified one (5.90%) case of deep-seated stromal corneal foreign body among the cases which were reported to have only superficial corneal foreign body on SLE. Two (50%) cases of suspected OSSN on SLE were ruled out on AS-OCT, whereas two (50%) cases of suspected OSSN on SLE were confirmed on AS-OCT. AS-OCT found a KF ring among two (12.5%) cases that were reported to have no KF ring on SLE. On both SLE and AS-OCT, 26 (81.2%) cases showed the same findings, whereas in 30 (49.2%) cases, AS-OCT rejected the suggested findings of the SLE. In six (18.8%) cases, SLE did not show any findings, but AS-OCT showed findings. Both SLE and AS-OCT showed no findings in 31 (50.8%) cases.

CONCLUSION

This study highlights the significant role of AS-OCT in enhancing the diagnostic accuracy of various corneal diseases. Its ability to detect additional findings in various corneal conditions such as keratoconus, corneal foreign bodies, OSSN, and KF ring in Wilson's disease underscores its value in clinical practice. The utility of AS-OCT in diagnosing subclinical corneal diseases which are beyond the scope of routine SLE has been demonstrated in our study. These capabilities make AS-OCT an effective additional diagnostic tool in evaluating cornea and should be routinely incorporated along with traditional SLE in evaluating various corneal diseases.