Posters

Long-term results from in vitro experiments modeling calcification of hydrophilic intraocular lenses due to intraocular air or gas

Poster Details

First Author: P.Gartaganis GREECE

Co Author(s):    P. Natsi   S. Alimisi   S. Gartaganis   P. Koutsoukos           

Abstract Details

Purpose:

The investigation of the opacification hydrophilic intraocular lenses (IOLs), due to the formation of calcific deposits is challenging and further progress depends on the availability of suitable models, which simulate closely in vivo systems with the possibility of understanding mechanisms underlying complex biological processes. Mineralization of IOLs may be accurately represented by phenomena taking place at the aqueous humor (AH)/IOL interface and can be fully characterized by analytical methods. Design of experiments to investigate full immersion of the IOLs in the AH or through contact with air bubble is a most suitable approach for in vitro studies.

Setting:

1. Department of Ophthalmology, 251 Hellenic Air Force General Hospital, Athens, Greece 2. Department of Chemical Engineering, Laboratory of Inorganic and Analytical Chemistry, University of Patras and FORTH-ICEHT, Greece 3. Department of Ophthalmology, Henry Dunant Hospital, Athens, Greece 4. Department of Ophthalmology, Medical School, University of Patras, Greece

Methods:

A special cell was constructed which ensured contact of hydrophilic IOLs with synthetic aqueous humor (SAH) the composition of which was the same as that of AH except for proteins and other organic compounds content. Air was introduced and maintained at pressure regulated over the range ca. 30 mmHg. As a result, SAH was displaced and a film of SAH of thickness <1 mm and diameter of 3 mm was maintained for time periods of up to 60 hours. Past this time contact with SAH was re-established and IOL remained In contact with SAH for up to 5 months.

Results:

The experiments in the present work were done at conditions of practically constant supersaturation. In our experiments calcium phosphate deposits formed in the area exposed to gas and was characterized by spectrometric methods and scanning electron microscopy. Prolonged exposure resulted in the development of subsurface calcific deposits, similar to the formations found in earlier our in vitro studies. Furthermore, depending on the radius of curvature of the meniscus formed at the IOL /simulated aqueous humor interface, local supersaturation may rise above the bulk SAH.

Conclusions:

Calcific deposits were found located first at the periphery of the air bubble in contact with the hydrophilic IOLs tested. The initiation of the formation of calcium phosphate took place at the air/SAH/IOL interface, because at the meniscus formed at the interface, the local supersaturation is higher promoting nucleation and further growth of crystallites. The formation of the first crystallites promoted further growth of calcium phosphate crystalline phases. Residence time of the IOLs in contact with SAH regulates rates and extent of calcification.

Financial Disclosure:

None