Purpose
To investigate the spectral-domain optical coherence tomography (SD-OCT) features of epithelial basement membrane dystrophy (EBMD) and to examine the reliability of SD-OCT in distinguishing EBMD from normal cornea.
Methods
Design: Case-control study.<br /> Participants: Forty-five individuals with EBMD and 45 age- and sex-matched controls with normal cornea presenting to the Quinze-Vingts National Ophthalmology Hospital, Paris, France.<br /> Methods: Participants were examined, and SD-OCT was performed. For each patient (case and control), 10 high-resolution horizontal scans and 10 high-resolution vertical scans were made in order to evaluate all structural corneal anomalies. All OCT scans were analyzed by 2 corneal specialists who were blinded to the patients’ clinical and topographic data. In vivo confocal microscopy (IVCM) was performed at the end to confirm or rule out the diagnosis of EBMD.<br /> Main outcome measures: Evaluation of the structural corneal changes occurring in EBMD cases based on SD-OCT findings.<br />
Results
Epithelial abnormalities were found in 86 out of 87 eyes with EBMD (45 patients) on SD-OCT scans. The main feature was the presence of irregular and thickened epithelial basement membrane duplicating and/or insinuating into the corneal epithelium layer. The second main feature was the presence of hyperreflective dots with or without a posterior shadow cone in the middle or superficial corneal epithelium layer. When an abnormal epithelial basement membrane protrusion was present, these dots were usually beneath the abnormal epithelial basement membrane. In some cases, we detected hyporeflective spaces between the corneal epithelial layer and the Bowman layer similar to a "corneal epithelial detachment". This separation between the corneal epithelial layer and the Bowman layer was sometimes associated with a cleavage within the corneal epithelial layer with a stair-step appearance. When using a control group of 45 normal patients, we observed a perfect agreement between IVCM and SD-OCT for the diagnosis of EBMD (k value 0.98).
Conclusions
Spectral-domain optical coherence tomography provides an accurate assessment of structural changes occurring in eyes with EBMD. These SD-OCT changes are easily detectable and allow for an accurate diagnosis especially in patients with no biomicroscopically visible corneal changes.