Despite advances in noninvasive imaging technologies, researchers say histopathology (HP) must remain the standard of care in measuring thicknesses in corneal and bulbar conjunctival tumors. Researchers compared the accuracy of these measurements using anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM), in a study published in the British Journal of Ophthalmology.
HP presents the challenge of obligatory tumor removal, regardless of malignancy, which leads to shrinkage of the tumor tissue, which naturally impacts measurement. Furthermore, researchers identified the steps to extract the tumor as “highly operator dependent” in the loosely arranged tissues around the eye, making it difficult to establish standards.
The study included 42 eyes of 35 participants (mean age of 48.7 years) with corneal or bulbar conjunctival tumors at a hospital in Belgium. They each underwent AS-OCT and UBM imaging. HP was conducted for all tumors in the 11 cases of surgical excision.
The anterior boundary was visualized in all tumors, but it was impossible to visualize the posterior margin of 12 tumors using AS-OCT and 4 using UBM, and therefore measurements were impossible in those cases.
AS-OCT and UBM measurements had strong correlations in measurement (P =<.001) yet details were better seen on AS-OCT than on UBM, the study explains.
“UBM is able to measure thickness with good reliability, but the images lack details. By contrast, AS-OCT has good resolution which aids in diagnosis and is able to reliably produce accurate measurements of thin lesions, but it fails when either the tumour is too thick or pigmented,” the researchers said. “Therefore, AS-OCT and UBM should be used in conjunction to facilitate the interpretation of tumour size, but neither technique replace HP yet, even when used in combination. Enhanced depth technology OCT may bring about a change in this situation in the future.”
Limitations of the study include the small, for statistical purposes, heterogeneous population of mostly benign lesions and the low number of included malignant lesions.
Lauwers N, Janssens K, Mertens M, et al. Anterior segment optical coherence tomography and ultrasound biomicroscopy for measuring thickness of corneal and bulbar conjunctival tumours. Br J Ophthalmol. Published online February 5, 2021. 10.1136/bjophthalmol-2018-312337