Microstructural assessment of rare corneal dystrophies using real-time in vivo confocal microscopy

Purpose: To analyse and describe three cases of rare corneal dystrophy and highlight their in vivo microstructural features. Methods: Subject 1 was diagnosed with a posterior stromal fleck corneal dystrophy. Two of her three children were also affected. Subjects 2 and 3 exhibited an almost identical clinical appearance on biomicroscopic examination, such that both clinically were diagnosed as having pre-Descemet's dystrophies. All subjects underwent in vivo confocal microscopy and approximately 300 sequential digital images were obtained and analysed for each cornea. Results: In vivo confocal microscopy of subject 1 demonstrated an abnormal appearance of numerous large ovoid particles, measuring 50-70 mum in diameter in the mid and posterior stroma as well as smaller hyperreflective dot-like intracellular deposits, of less than 1 mum diameter. Despite the near-identical clinical appearance, subjects 2 and 3 could be clearly differentiated by in vivo confocal microscopy. Subject 2 exhibited small, irregular, optically dense particles, mainly in the anterior stroma, whereas subject 3 possessed classical involvement of the stroma immediately adjacent to Descemet's membrane, with numerous regular, small, hyperreflective particles. Conclusions: The ability of in vivo confocal microscopy to localize and accurately measure various elements in different corneal layers may help to resolve whether abnormalities are intra- or extracellular, and aid clearer differentiation of rare corneal disorders.