EPOS

European Paediatric Ophthalmological Society

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The Use of the VisanteTM non-contact anterior segment optical coherent tomography (OCT) in the monitoring and imaging of corneal crystals in cystinosis

Pilling Rachel¹, Norris Jonathan¹, Matthews Brian¹, Aine Rice¹, Simmons Ian^1
1St James's University Hospital, Leeds, UK.

Introduction: We demonstrate the use of the Visante® non-contact anterior segment OCT in the monitoring and imaging of paediatric patients attending bimonthly cystinosis clinics. Corneal features of cystinosis include needle shaped crystals found initially in the superficial and peripheral cornea. These subsequently progress centrally and posteriorly to involve endothelium. This process carries a poor prognosis with ensuing corneal oedema and epithelial erosions. Corneal thickness is also increased. Method: High resolution OCT scans (3mm x 10mm, 512 A-scans in 250 ms with an axial resolution of 18μm) were used for the purpose of recording density and position of corneal crystals. Results: Cystinosis crystals are clearly visible using high resolution OCT. Furthermore, the amount of reflectivity of the corneal crystals in the OCT images correlates with clinical photographs in terms of number and density of crystals. Discussion: We highlight the use of non contact anterior segment OCT as a non-invasive tool for monitoring of cystinosis crystals. It confers several advantages to previously reported monitoring systems. It is easier to operate than an anterior segment camera with a very fast acquisition time (250ms) which is particularly important in the paediatric patient. The depth of crystals can be more easily scrutinized than on slit lamp examination. Corneal pachymetry can also be recorded. OCT may be a more objective method of monitoring the effect of topical cysteamine drops potentially removing observer bias. Thus, one potential benefit may be to improve parental compliance with chronic topical therapy, if they are able to visualize a quantifiable reduction in crystal density on OCT. Conclusion: High resolution OCT is an effective tool for the monitoring and visualization of corneal crystals in cystanosis. To our knowledge the use of anterior segment OCT in imaging corneal cystinosis crystals has not previously been reported.