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First Author: N.Borah INDIA
Co Author(s): R. Phukan S. Buragohain
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To study under scanning electron microscope, whether low cost single piece PMMA IOL(10-15$) have higher surface irregularities/roughness when compared to relatively expensive single piece PMMA IOL(20-30$) which may contribute towards higher incidence of PCO.
In developing countries like India, manual small incision cataract surgery(MSICS) with polymethylmethacrylate(PMMA) IOL implantation is one of the most commonly performed ophthalmic surgeries. MSICS with PMMA IOL implantation play an important role in clearing millions of cataract backlog in India. These IOLs cost 10-15$ per piece and are mostly manufactured locally. Due to low cost of these PMMA IOL MSICS surgery cost is substantially less. However, studies show that following MSICS and PMMA IOL implantation the incidence of posterior capsular opacification(PCO) is higher than phacoemulsification with foldable intraocular lens implantation surgery.
We have studied suface characteristics(morphology) of 14 single piece PMMA IOL in SEM(Carl Zeiss, model 1430VP). Period of study, from January, 2011 to February, 2013. All the IOLs were procured randomly from the local agencies dealing with ophthalmic products. Samples were studied in room temperature (18-20 degree C). Three different zone of the IOLs were studied, 1. Optic-heptic junction, 2. dialling hole 3. edge of the optics. These low cost PMMA IOL were compared with two relatively expensive single piece PMMA IOL available in India. IOL were prepared carefully and then studied in 160 X, 500 X and 1000 X magnification in SEM. Any surface irregularity/roughness which were detected under SEM were divided into mild, moderate and severe degrees.
Total 14 single piece PMMA IOL were studied (12 low cost and 2 relatively expensive). All 14 IOL had some form of surface irregularities/roughness in SEM examination. 13 IOL had mild to severe degree irregularities/roughness involving the dialling hole, 11 IOL had moderate to severe degree of roughness at the optic-heptic junctions, 7 had mild to moderate degree optics edge roughness. SEM examination of the optics (central 3-4mm) of all 14 IOL showed a smooth surface in 160 X magnification. In SEM study there was no difference in surface irregularities between low or relatively higher cost IOL.
In SEM analysis all 14 single piece PMMA IOL samples (both low cost and relatively expensive) showed moderate to severe degree of surface irregularities i.e. scratches, pitting, sharp protrusions and rough dialling holes. Maximum irregularities(92.9 %) were detected at dialling holes and at optic-heptic junctions(78.6%). Surface irregularities and roughness detected in single piece PMMA IOL, specially on the edge of the optics may contribute towards unobstructed priliferation of lens epithelial cells on the posterior capsule leading to increased incidence of posterior capsular opacification. Maintaining more stringent standards during manufacturing of these low cost single piece PMMA IOL may reduce these surface irregularities.