Abstract
Purpose::
AquasenseTM hydrophilic acrylic intra ocular lens (IOL) was used in the northwest UK. Post-operative opacification occurred in a number of eyes. We studied seven of extracted lenses. The aim was to evaluate microscopic changes and find an explanation for this process.
Methods::
We have used a wide range of Microanalysis techniques. Electron microscopic analysis disapproved presence of any mineral on the lens surfaces. Analysis of the lens cross sections showed parallel bands of calcium deposits inside the lens. This was best showed by Transverse Micro-Radiography. Computerized analysis of micro-X-rays gave an accurate figure for the amount of minerals in each lens. A case control study was designed to compare 5 affected lenses with a control lens (clear).
Results::
This technique proved significant mineral deposition on the opacified lenses compared with the control lens. We have also measured calcium deposit distance from surface 52.2µm (range of 27.1-90.2) and the thickness of calcium band 152.8 µm. The deposit was made of Hydroxyapetite. Diffusion of the minerals through the highly permeable lens material can lead to this condition. Similar reports have been made in high water content IOLs.
Conclusions::
Calcium band was detected to be closer to anterior surface that the posterior surface of the opacified IOLs. The high water content of this type of the IOL increased higher permeability and therefore diffusion of minerals into the IOL. At least some of Hydrophillic lenses have tendency to allow calcium ions to travel inside theor material. Calcium and Phosphorus crystallisation proved to be amorphous Hydroxyapatite, Ca10 (PO4)(OH)2, using X-Ray Diffraction (XRD) Hydroxyapatite is a highly biocompatible Calcium phosphate that closely resembles the chemical structure of bone. For the first time, the IOL Micro-X-rays was used to demonstrate calcification. It also allowed us to quantify the amount of calcification in different samples. This technique can be utilised in future research in this area.
Keywords: intraocular lens • calcium • microscopy: electron microscopy