ESCRS - PP22.05 - Higher Phosphate Concentrations As Seen In Aqueous Humor Of Diabetic Patients Increase Intraocular Lens Calcification

Higher Phosphate Concentrations As Seen In Aqueous Humor Of Diabetic Patients Increase Intraocular Lens Calcification

Published 2022 - 40th Congress of the ESCRS

Reference: PP22.05 | Type: Free paper | DOI: 10.82333/mdt8-bf58

Authors: Rebecca Buhl* 1 , Timur Yildirim 1 , Sonja Schickhardt 1 , Leoni Britz 1 , Ingo Lieberwirth 2 , Gerd Auffarth 1 , Ramin Khoramnia 1

1The David J. Apple International Laboratory for Ocular Pathology,Department of Ophthalmology, Heidelberg University Hospital,Heidelberg,Germany, 2Max Planck Institute for Polymer Research,Mainz,Germany

Purpose

Clinical evidence suggests a causal association between elevated aqueous humor phosphate concentration and the risk of intraocular lens (IOL) calcification. To investigate this hypothesis the influence of different phosphate concentrations on IOL calcification was evaluated in an in vitro electrophoresis model.

Setting

Experimental in vitro laboratory investigation at the David J. Apple International Laboratory for Ocular Pathology, Department of Ophthalmology, University of Heidelberg, Germany.

Methods

20 hydrophilic IOLs (CT Spheris 204, Zeiss and Lentis L-313, Oculentis) and a hydrophobic control IOL (Clareon CNA0T0, Alcon) were exposed to both physiologic (10 mM) and elevated (14 mM) disodium hydrogen phosphate (Na2HPO4) concentrations, similar to aqueous humor of patients suffering from diabetic retinopathy. IOL calcification was analyzed by light microscopy, alizarin red staining, von Kossa staining, scanning electron microscopy, energy dispersive x-ray spectroscopy, and transmission electron microscopy with electron diffraction.

Results

Elevated phosphate concentrations were clearly associated with increased IOL calcification. Semiquantitative analysis of IOL surfaces and IOL cross-sections showed no calcification in CT Spheris IOLs and calcification in 4 Lentis IOLs when exposed to 10 mM Na2HPO4, compared to 7 and 11 positive analyses when exposed to 14 mM Na2HPO4. The presence of IOL calcification was confirmed by all analyses and hydroxyapatite, the calcium phosphate present in in vivo calcified IOLs, was detected. No calcification corresponding to in vivo calcification was detected in the control IOLs.

Conclusions

Elevated phosphate concentrations comparable to diabetics’ aqueous humor increase the risk of IOL calcification. Therefore, these results explain clinical observations showing an increased incidence of IOL calcification in patients with diabetes.