In Vivo Confocal Microscopy and Anterior Segment Optical Coherence Tomography Analysis of the Cornea in Nephropathic Cystinosis

Abstract

To analyze the corneas of patients with nephropathic cystinosis using in vivo confocal microscopy (IVCM) and anterior segment optical coherence tomography (AS-OCT). Prospective case series. Sixteen eyes of 8 patients with nephropathic cystinosis aged 8 to 21 years. The ophthalmologic evaluation included best-corrected visual acuity, evaluation of photophobia (0-4), slit-lamp biomicroscopy analysis, intraocular pressure measurement, evaluation of crystal density using a slit-lamp-based scoring of the cornea, as well as AS-OCT and IVCM analysis. The depth of crystal deposition (DCD) in the central cornea and the central cornea thickness (CCT) were assessed using AS-OCT and IVCM. The IVCM images were evaluated for crystal density in each corneal layer and an IVCM score was calculated for each eye. All eyes had corneal crystal deposits, with a mean slit-lamp photography score of 2.90+/-0.13 (range, 2.75-3.00). Using AS-OCT, corneal crystals were observed in all eyes. These crystals appeared as hyperreflective punctuate deposits, predominantly observed within the anterior stroma. Measured with AS-OCT, the mean depth of DCD in the central cornea was 291.40+/-81.42 microm (range, 200-531 microm); the mean CCT was 543.47+/-29.62 microm. Using IVCM, the crystals appeared as spindle, needle-shaped, and fusiform hyperreflective bodies measuring from 1 to 175 microm in length and 1 to 30 microm in thickness. Except for the endothelium, randomly oriented crystals were observed in all corneal layers, with the greatest density observed within the anterior stroma. Measured with IVCM, the mean DCD was 426.07+/-88.19 microm (range, 284-531 microm); the mean CCT was 531.87+/-34.77 microm. There was no significant difference between the CCT measurements obtained with IVCM and with AS-OCT (mean difference, 11.31 microm; P = 0.07). Nevertheless, the DCD was significantly higher with IVCM than with AS-OCT (mean difference, 126.25 microm; P<0.0001). In patients with nephropathic cystinosis, IVCM could precisely quantify the density of crystals within the central cornea. Anterior segment OCT and IVCM should be used in further studies evaluating crystal deposition in patients with nephropathic cystinosis. The authors have no proprietary or commercial interest in any materials discussed in this article.