The Cylite Hyperparellel OCT (HP-OCT), designed and manufactured in Melbourne, has been the subject of recent research into angle closure assessment and published in the British Journal of Ophthalmology.
The study, conducted by researchers from the Singapore Eye Research Institute, evaluated the reproducibility and agreement of angle closure assessment of the HP-OCT in comparison to a swept-source OCT (SS-OCT) and gonioscopy.
Data was obtained from a cross-sectional study of subjects recruited from the Singapore National Eye Hospital, with either confirmed glaucoma or defined as glaucoma suspects.
A total of 77 consecutive subjects (154 eyes) took part in the study and were scanned with both the HP-OCT and the SS-OCT, as well as undergoing gonioscopy.
Of the OCT scans, only the horizontal B-scans were included in the study.
The mean age of the subjects was 63 (range 44-79) and the prevalence of angle closure defined by gonioscopy examination was 19.5%.
Identification of the scleral spur (usually necessary for OCT evaluation of the angle) and assessment of iridotrabecular contact was successful in all but one angle image on both devices, with the one subject’s sector being ungradable due to pterygium.
No differences were found between the devices in the proportion of gradable images amongst eyes that could be imaged.
The reproducibility of iridotrabecular detection by the HP-OCT was regarded by the authors as excellent and the agreement between the HP-OCT and the SS-OCT was rated as very good.
When a comparison was made with gonioscopy, the agreement of angle closure detection with the HP-OCT was slightly lower, but better than with SS-OCT. However, no differences in the diagnostic ability to detect gonioscopic angle closure was observed between the two OCT devices.
A noteworthy observation was that the trabecular meshwork was identified on most unprocessed HP-OCT scans regardless of angle status, whereas it was not identified on any equivalent scans using the SS-OCT.
The authors suggested that the Hyperparallel OCT’s unique ability to visualise the trabecular meshwork could be used as a landmark for detecting iridotrabecular contact rather than using manual or automated methods of identifying the scleral spur and would better approximate how angle closure is identified on gonioscopy.
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