Abstract
Purpose: :
Anterior Segment Optical Coherence Tomography (AS-OCT) is a novel imaging modality that provides high-resolution corneal scans by non-contact examination. We investigate microbial keratitis (MK) in a prospective longitudinal study with AS-OCT. We assess the ability of Visante AS-OCT to measure corneal thickness (CT) and infiltrate thickness (IT) in the affected area and investigate the temporal change of these parameters during the course of the disease.
Methods: :
Twenty seven patients with suspected microbial keratitis underwent slit-lamp examination and AS-OCT scans on day of presentation and days 3, 7 and 14 post-presentation. The scanning beam passed through the infiltrate centre at a specific meridian for all scans. Measurements of CT and IT were obtained in the centre of the infiltrated area on high-resolution images with calliper tools provided by the Visante OCT software (version 1.1.2). Scans and measurements were carried out by the same investigator.
Results: :
Clinical resolution occurred in 26 cases; mean CT decreased from 898m (SD±204) on presentation to 753m (SD±161) [p<0.01], 677m (SD±178) [p<0.001] and 584m (SD±146) [p<0.001] on days 3, 7 and 14 respectively. Mean IT decreased from 394m (SD±182) to 319m (SD±162) [p=0.16], 295m (SD±135) [p=0.06] and 207m (SD±87) [p<0.001] respectively. CT and IT decreased significantly more rapidly (48m/day and 25m/day respectively) in the first 3 days of treatment compared to later time intervals, 3-7 and 7-14 days (p<0.05). In one case with clinical deterioration, CT decreased and IT increased before penetrating keratoplasty was required for perforation.
Conclusions: :
This is the first study to measure in-vivo CT and IT during the clinical course of MK. Clinical resolution is associated with a rapid reduction of CT and IT the first 3 days of treatment; CT decreases significantly by day 3, whereas IT only decreases significantly by day 14. AS-OCT provides serial objective assessment of the extent and depth of corneal inflammation.
Keywords: cornea: clinical science • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • inflammation