Illuminating Blurry Vision: Visualization of Corneal Protein Deposition With Immunofluorescence in Two Illustrative Case Reports.

Background: Monoclonal gammopathy of undetermined significance (MGUS) is an asymptomatic, premalignant disease with a progression rate of 0.5%-1% per year to multiple myeloma. It can rarely present with significant ocular symptoms in the context of crystalline keratopathy, necessitating medical and surgical interventions. Lattice corneal dystrophy Type I (LCD-1), a rare inherited disorder caused by mutations of Methods: Medical records were reviewed. Hematoxylin and eosin, special staining, immunohistochemistry, and immunofluorescent techniques were performed. A literature review was performed. Results: Case 1: Eosinophilic accumulations of the cornea were highlighted with PAS-D and IgG-kappa by immunohistochemistry, whereas immunofluorescence (IF) technique demonstrated IgG-kappa (2+) staining in the stroma with rare globules in the epithelium. Case 2: Amorphous, eosinophilic deposits within the corneal stroma were congophilic with apple-green birefringence on polarized light. Thioflavin T highlighted the amyloid through immunofluorescence. Mass spectrometry detected a peptide profile consistent with ATGFBI-type amyloid deposition. Conclusion: Immunofluorescence can be helpful in the workup of corneal protein deposition, such as MGUS-related crystalline keratopathy and LCD-1.