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Implantable collamer lens(ICL)
The Implantable Collamer Lens (ICL) is a soft, flexible, posterior chamber phakic intraocular lens made of collagen-copolymer material called Collamer. Studies have shown ICL implantation is safe and effective for correcting myopia between -3 to -25 diopters and astigmatism up to -6 diopters. It provides stable refractive results with few complications over 4 years. Toric ICL models were found to be superior to LASIK in safety, efficacy, predictability and stability for high myopic astigmatism. The procedure is reversible and preserves corneal tissue, reducing risks compared to LASIK.
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Implantable collamer lens(ICL)
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- 2. ICL is madefrom 100 % biocompatible soft flexible gel lens The material porcine Collagen is polymerised with HEMA Hence collagen copolymer = Collamer Posterior chamber Phakic IOL model
- 3. History Fathers of PhakicIOL – Choyce,Strampelli, Barraquer conduted first ever trials using AC refractive lenses to correct high myopia in 1950s. But due to unacceptable complications such as loss of corneal endothelial cells,iris atrophy, PAS , these especially the angle supported lenses were phased out of the market.
- 4. First model madeby Fyodorov in 1980s in Russia of a collar button configuration. First implant in Europe in 1993. Concept of soft phakic lens.
- 5. This material ofCollamer was made by STAAR Visian Surgicals which provide good biocompatibility ,Optical capability, with a lens resting behind the iris in ciliary sulcus.
- 8. Prerequisites Residual bed afterLASIK < 250 microns Initial Corneal thickness < 480 microns Stable refraction <0.5 D change in previous 12 months No ocular pathology
- 9. 3 variants ofPhakic IOL Angle supported and Iris claw lenses are the AC variants. ICL is the PC variant. Due to reasons of complications associated with ACIOL design
- 10. FDA approved itsuse in Myopia and Myopic astigmatism in year 2005 via NEI sponsored study. Indication in Myopia of -3 to -25 Dioptres Astigmtism up to – 6 Dioptres Thin Corneas
- 11. Measurement of whiteto white diameter Using Orbscan,UBM or calipers Add 0.5 mm to horizontal WW measurement for ICL overall length ICL too short – lens vault less, exposes to risk of Anterior capsular cataract ICL too long – lens vault exceeds – angle crowding –closed angle glaucoma
- 12. Vault: Ideally should be500 microns= one corneal thickness High vault - Iris chaffing pigment dispersion,glaucoma Low vault - ICL contact with crystalline lens – cataract formation.
- 13. Procedure Under topical anaesthesia,0.6 mm side port , 3.2 mm clear corneal incision on steep meridian. Lens introduced into the soft silicone tip with micro incision injector and positioned behind iris with help of blunt spatula. Lens is implanted temporally and gently rotated to align the axis with the cylindrical axis of the patient.
- 14. Complete removal ofviscoelastic material Miotic agent injected Incision closed by hydrating incision Peripheral iridotomy – intraoperatively with vannas scissors ,sufficiently wide, positioned superiorly , well away from haptics – to provide outlet for aqueous flow around lens.
- 16. Reports Kamiya et alin a studied the long term clinical outcomes of implantation of these implantable lenses for Myopia in 56 eyes of 34 patients with refractive errors of - 4.00 to – 15.25 D . Kamiya K, Shimizu K . Implantable Collamer lens for hyperopia after radial keratotomy . J Cataract Refract Surg 2008; 34(8) : 1403-4
- 17. They concluded implantationis safe and effective with predictable and stable refrative results during a four year observation period.
- 18. Kamiya et alalso compared Collamer toric ICL with wavefront guided LASIK for high myopic astigmatism and found that all eyes in ICL group and 71 percent in LASIK were within +/- 1.00 D of targetted SE correction at six months.
- 19. Hence it wasconcluded that these Toric ICLs were superior compared to LASIK in all measures of safety, efficacy predicability,stability. Thus overall complication rate was low and patients have good visual recovery.
- 20. According to astudy by Sanders et al ,the incidence of anterior subcapsular opacities and cataracts were studied after ICL implantation.Approximately 6 – 7 % of eyes developed anterior subcapsular opacities at over 7 yrs but 1 % progressed to cataract. Sanders DR. Anterior subcapsular opacities and cataracts 5 years after surgery in the visian collamer lens FDA trial . J Refract Surg 2008;24(6): 566-70
- 21. With the advancementsin anterior segment imaging , ultrasonic biomicroscopy , Optical coherence tomography and Scheimpflug imging ,valuable information is now provided about anterior segment anatomy for phakic Intraocular lenses(ICL) for correction of moderate to high refractive errors.
- 22. Advantages The procedure isreversible unlike LASIK The quality of vision is usually better It creates a small corneal incision so astigmatism is minimum Corneal tissue is not removed ,hence adequate tear layer Reduction of risk of optical distortions an higher order aberrations
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