Purpose:
To evaluate the utility of anterior segment optical coherence tomography (AS-OCT) in the objective assessment of post-infectious corneal opacities.
Methods:
A prospective pilot study of 5 patients with post-infectious corneal opacities previously treated with antibiotics at the New York Eye & Ear Infirmary General Clinic was carried out. A complete chart review including antibiotic and steroid use was performed. Lesion slit lamp photography, AS-OCT (Ophthalmic Technologies Inc. [OTI], Toronto, Canada), and ultrasonic pachymetry was carried out for each patient. Vertical and horizontal clinical measurements were evaluated. Software provided with the AS-OCT machine was used to measure lesion vertical and horizontal dimensions, lesion thickness, corneal thinning, central corneal thickness, and reflectivity (scar and normal adjacent cornea). Photographs were subjectively ranked by a blinded observer for scar density and compared to the AS-OCT scar reflectivity values (Figure 1: Representatitive photo and AS-OCT image with measurement values).
Results:
All scars resulted from culture positive, soft contact lens-related corneal ulcers that were successfully treated with antibiotics. Lesion reflectivity averaged 710 units and normal corneal reflectivity averaged 535 units. Average lesion thickness was 457µm (pachymetry) and 552µm (OCT) and vertical length was 3.0mm (slit lamp) and 3.5mm (OCT). Subjective scar density on photography correlated well with corneal OCT reflectivity measures.
Conclusions:
Anterior segment OCT is a novel imaging modality for post-infectious corneal opacities which can provide an objective measure of corneal reflectivity that correlates well with lesion density on photography. Because OCT provides an objective reflectivity value, it can be used to quantify post-infectious corneal opacities and their response to controversial medical therapies intended to decrease scarring such as steroids. Further study will be necessary to determine if the differences in lesion thickness, and lesion height and width are the result of measurement error or some other factor.
Keywords: keratitis • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • bacterial disease