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

## TL;DR

This paper presents two case studies using immunofluorescence to visualize protein deposits in corneal diseases linked to MGUS and LCD-1.

## Contribution

The study demonstrates the utility of immunofluorescence in diagnosing corneal protein deposition disorders.

## Key findings

- Immunofluorescence detected IgG-kappa deposits in a case of MGUS-related crystalline keratopathy.
- Thioflavin T and immunofluorescence confirmed ATGFBI-type amyloid in a case of LCD-1.
- Mass spectrometry supported amyloid diagnosis in LCD-1.

## Abstract

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 TGFBI, manifests with amyloid deposition within the corneal stroma and causes visual impairment. Here, we pictorially highlight protein deposition using immunofluorescence in two representative cases, both having undergone penetrating keratoplasty for blurry vision.

Medical records were reviewed. Hematoxylin and eosin, special staining, immunohistochemistry, and immunofluorescent techniques were performed. A literature review was performed.

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.

Immunofluorescence can be helpful in the workup of corneal protein deposition, such as MGUS‐related crystalline keratopathy and LCD‐1.