Noninvasive assessment of corneal alterations associated with monoclonal gammopathy

Aggregation of monoclonal immunoglobulin can lead to organ damage. However, the necessity of invasive examination such as biopsy has hampered better understanding of the pathophysiology. Corneal crystalline deposition is a rarely reported but known ocular manifestation of multiple myeloma. It is unclear whether the cornea is a common target of monoclonal immunoglobulin deposition. We conducted a prospective clinical case-control study to objectively quantify monoclonal gammopathy-associated corneal changes as well as any therapeutic response. Using an ophthalmic Scheimpflug camera imaging for noninvasive corneal assessments, we quantified densitometry values in 30 patients. Although none had crystalline keratopathy, corneal transparency in monoclonal gammopathy patients was significantly impaired compared to that in age-matched controls, based on noninvasive Scheimpflug camera imaging. Furthermore, treatment for multiple myeloma seemed to eradicate the diffuse aggregation of monoclonal proteins. Our results indicate that exposure to monoclonal immunoglobulin may induce the accumulation of monoclonal immunoglobulin in the cornea, and ophthalmic examinations such as corneal densitometry measurements with a Scheimpflug camera may be useful for noninvasive evaluation of monoclonal immunoglobulin deposition diseases.