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Establishing an objective biomarker for corneal cystinosis using a threshold-based SD-OCT imaging algorithm

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First Author: L.Keidel GERMANY

Co Author(s):    C. Elhardt   K. Hohenfellner   S. Priglinger   C. Wertheimer   N. Luft   C. Priglinger     

Abstract Details

Purpose:

The purpose of the present study was to establish a semiautomated threshold-based image segmentation algorithm to detect and objectively quantify corneal cystine crystal deposition in ocular cystinosis with anterior-segment optical coherence tomography (AS-OCT).

Setting:

University Eye Hospital, Ludwig-Maximlians University, Munich, Germany. Prospective observational comparison study.

Methods:

88 eyes of 45 cystinosis patients from the German Cystinosis Registry Study carried out by the Interdisciplinary Cystinosis Clinic Rosenheim and 68 eyes of 35 healthy control subjects were imaged using AS-OCT (Cirrus HD-OCT 5000, Carl Zeiss Meditec AG, Jena, Germany). As an initial step, B-scan images were subjectively analyzed for typical changes in morphology in comparison to healthy controls. From the knowledge gained, an objective semi-automated B-scan image segmentation algorithm was developed using a grey scale value-based threshold method to automatically quantify corneal crystals.

Results:

On AS-OCT B-scans, corneal crystals appeared as hyperreflective deposits within the corneal stroma. The crystals were distributed either in all stromal layers (43 eyes, 49%), or confined to the anterior (23 eyes, 26%) or posterior stroma (22 eyes, 25%), respectively. The novel automatic B-scan image segmentation algorithm was most efficient in delineating corneal crystals at higher greyscale thresholds (e.g. 226 of a maximum of 255). Significant differences in suprathreshold greyscale pixels were observable between cystinosis patients and healthy controls (p<0.001). In addition, the algorithm was able to detect an age-dependent depth distribution profile of crystal deposition.

Conclusions:

Objective quantification of corneal cystine crystal deposition is feasible with AS-OCT and can serve as a novel biomarker for ocular disease control and topical treatment surveillance.

Financial Disclosure:

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