Abstract
Purpose: :
Cystinosis is a metabolic disorder that results in intracellular cystine accumulation in the eye and other organs due to a mutation in the lysosomal cystine transporter, cystinosin (CTNS). Corneal cystinosis causes significant morbidity (severe photophobia, visual loss), despite standard topical and systemic therapy. Using in vivo confocal microscopy, we assessed corneal cystine crystal formation in a novel animal model of cystinosis, the Ctns-/- mouse.
Methods: :
Freshly enucleated and fixed eyes from 6-7 month old Ctns -/- mice were subjected to in vivo confocal reflectance microscopy. A 24X, 0.6 NA objective with a surface-contact tip and variable working distance (0 - 1.5 mm) was used to obtain 9 um optical sections (FWHM).
Results: :
Corneal crystals were identified in all 9 Ctns-/- eyes that were examined older than 6 months of age. Cystine crystals were identified as small, 20 micron long, needle-like crystals in the peripheral cornea. Older Ctns-/- mice (7 Month) developed aggregates of brightly reflecting material, presumably cystine, within the central cornea that were associated with neovascularization and inflammation (see image).
Conclusions: :
Confocal microscopy identified corneal crystals and cystine aggregates in 6-7 month old Ctns-/- eyes. These findings suggest that the Ctns-/- mouse can be used as a model for developing and evaluating novel therapeutic strategies to treat corneal cystinosis in humans.
Keywords: cornea: stroma and keratocytes • transgenics/knock-outs • imaging/image analysis: clinical