ESCRS - PP16.12 - Hydrophilic Intraocular Lens Calcification And The Role Of Surface Charge

Hydrophilic Intraocular Lens Calcification And The Role Of Surface Charge

Published 2022 - 40th Congress of the ESCRS

Reference: PP16.12 | Type: ESCRS 2022 - Posters | DOI: 10.82333/xvnt-vw46

Authors: Panos S. Gartaganis* 1 , George Ziomas 2 , Theodora Kourassi 2 , Panagiota Natsi 2 , John Kalatzis 2 , Sotirios Gartaganis 3 , Petros Koutsoukos 2

1Ophthalmology,251 Hellenic Airforce General Hospital,Athens,Greece, 2Chemical Engineering, Laboratory of Inorganic and Analytical Chemistry,University of Patras and FORTH-ICEHT,Patras,Greece, 3Ophthalmology,School of Medicine,University of Patras,Patras,Greece

Purpose

The aim of this experimental approach was to investigate the mechanism of the selective formation of calcium phosphate in poly-2-(hydroxyethyl methacrylate) (pHEMA) intraocular lenses (IOLs) in stable supersaturated solutions that had a simulated aqueous humor composition.

Setting

1. Department of Ophthalmology, 251 Hellenic Air Force General Hospital  2. Department of Chemical Engineering, Laboratory of Inorganic and Analytical Chemistry, University of Patras and FORTH-ICEHT, Greece 3. Department of Ophthalmology, Medical School, University of Patras, Greece 

Methods

ζ potential, was measured in porous pHEMA IOL plugs made of sliced  IOL material (18% water content)  inserted in a cylindrical cell, capped by perforated platinum electrodes. The flow of electrolyte through the porous plug was achieved by applying a differential pressure between two containers containing the electrolyte solutions. The flow of electrolyte across the surface of the IOL plugs creates a potential difference, ΔΡ, termed streaming potential, Es, at the two sides of the cell, which measured by two platinum electrodes. The ratio Es/ΔΡ is proportional to the potential according to Smoluchowski equation.

Results

The measurements revealed that the pHEMA IOLs surface exhibits negative charge increasing with pH. Ιncreasing the electrolyte concentration resulted in higher negative surface charge on pHEMA. Hydroxyapatite (HAP) is deposited selectively on the surface of hydrophilic IOLs at rates depending on the supersaturation of electrolyte solution in contact.  The deposition of HAP in intraocular lenses resulted in a further increase in their negative charge. This is indirect evidence of the presence of fixed active sites for nucleation and crystal growth of HAP on pHEMA.   

Conclusions

The results support the hypothesis that the increase of the pHEMA surface charge is due to the ionization of the hydroxyl groups on the surface of pHEMA, which provides the active sites needed for the initiation of nucleation and further growth of the HAP.