Abstract
Purpose: :
Several reports have noted the presence of hyper-reflective epithelial cells during clinical confocal microscopy (CM) of corneas that concurrently show diffuse punctate staining by sodium fluorescein (FL). The current study evaluated whether these two phenomena represent changes affecting the same set of epithelial cells.
Methods: :
Guinea pig eyes freshly excised within 1 h post-mortem were treated by topical application of 0.001% PHMB solution for 1 minute. Control eyes received 0.9% saline for the same period. Epithelial changes were observed with a slit-lamp bio-microscope (SLB) after application of 1% FL. An 8 mm2 window created from a filter paper mask was laid over the cornea to demarcate an area of interest and images of this region captured using both a clinical confocal microscope (HRT-RCM III) and a laboratory fluorescent microscope (Olympus FV1500). Software overlay of similar cell fields from each instrument was used to identify common features.
Results: :
SLB evaluation confirmed the presence of diffuse superficial punctate staining in test eyes and minimal or no observable staining in control eyes. Overlay of images of the same corneal area taken by fluorescent and clinical CM indicated that cells showing hyper-fluorescence in fluorescent CM images corresponded closely in position to those showing hyper-reflectivity in clinical CM images.
Conclusions: :
In a diffusely stained cornea, hyper-reflective cells observed using clinical CM are likely to also show staining with FL.
Keywords: cornea: epithelium • drug toxicity/drug effects • contact lens