THE VALUE OF ANTERIOR SEGMENT OPTICAL COHERENCE TOMOGRAPHY IN THE PREDICTION OF THE ORIGIN OF MICROBIAL KERATITIS

to analyze anterior segment OCT aspects of different types of infectious keratitis (IK) and attempt to correlate them with clinical aspects and microbiological results.

Ophthalmology department at HASSAN II university hospital, SIDI MOHAMED BEN ABDELLAH university Fez Morocco

A descriptive and analytical retrospective study of patients admitted for KI treatment from January 2019 to January 2023. We analyzed 375 cases of patients suffering from a corneal abscess, of which 97 had a positive sample. All patients having a complete file, a usable OCT image, and a positive sample were included. To predict the germ that causes the various forms of keratitis, two evaluators examined the clinical aspects and two others studied the OCT aspects. Subsequently, an analysis combining the two types of aspects was carried out. Sensitivities were calculated and a multivariate analysis was conducted for clinical aspects and OCT signs according to the group of germs identified.

Combined clinical and OCT signs identified a virus in 98% of cases (p 0.01), a gram-positive bacteria (GPB) in 77.3% (p 0.00), a gram-negative bacteria (GNB) in 77.8% (p 0.00), and a fungal infection in 100% (p 0.00). Clinical signs alone allowed the suspicion of a virus just in 75% of cases (p 0.001), a GPB in 40.9% (p 0.018), a GNB in 33.3% (p 0.017), and a fungal infection in 40% (p 0.02).

In the Anterior Segment Optical Coherence Tomography (AS-OCT) of all patients, stromal edema was observed in 75% of cases. For cases of Gram-Negative Bacteria (GNB) keratitis, stromal thinning was evident in 85% of cases. Gram-positive bacteria (GPB) keratitis was characterized by a well-defined infiltrate without any thinning in 87%.

The AS-OCT presentation of herpetic keratitis was a fusiform stromal opacity accompanied by a stromal scar, epithelial remodeling, and corneal edema (92%). In fungal keratitis, the most frequently observed AS-OCT features were a diffuse infiltrate with indistinct boundaries (89%), anterior stromal cystic spaces (83%), an endothelial plaque with blurred boundaries with the cornea (80%), and stromal thinning (65%).

Numerous studies exist in the literature that examine the Optical Coherence Tomography (OCT) aspects during Infectious Keratitis (IK). However, there is a scarcity of studies focusing on qualitative analysis. Numerous publications have identified several characteristic signs based on the causative germ.

Our study confirm that Anterior segment-optical coherence tomography (AS-OCT) allows qualitative analysis, it should be systematic in all situations of infectious keratitis especially in cases when the microbiological analysis doesn’t contribute in the diagnosis.