Mechanism of Intraocular Lens Calcification After Pseudophakic Endothelial Keratoplasty

The purpose of this study is to present an experimental model that explains the calcification pattern of hydrophilic acrylic intraocular lenses (IOLs) following endothelial keratoplasty (EK) procedures using the intracameral injection of air or gas. Pseudophakic eyes with hydrophilic acrylic IOLs undergoing EK procedures with intraocular air or gas injection are at risk of IOL calcification. Using air/aqueous humor (AH) dynamics, we attempted to explain the physicochemical mechanisms operating upon filling the anterior chamber with air (or gas) at pressures of at least 30-40 mmHg and for a period of 10-60 minutes in the presence of a hydrophilic acrylic IOL. After a short period of time, usually 10-15 minutes, the air bubble was reduced to 60-90% of the anterior chamber volume, completely covering the pupil and hydrophilic acrylic IOL surface. We have constructed a constant temperature and pressure artificial eye anterior chamber reactor (ACEACR) to simulate the anterior chamber air/gas pressure dynamics involved in applying EK surgery procedures in the presence of a hydrophilic acrylic IOL. The analysis of the opacified IOLs in the test model showed deposits of calcium phosphate crystallites on the surface of calcified IOLs similar to clinical findings. Calcific deposits appeared as a white circular area outlining the mineralization front of the interface between the air/gas bubble and the IOL exposed in synthetic aqueous humor (SAH). The calcification pattern of hydrophilic acrylic IOLs following EK procedures is caused by the development of locally higher calcium and phosphate concentration in comparison with the corresponding bulk AH, inside the AH meniscus formed at the air/bubble/IOL interface.