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Intra corneal Inlays for presbyopic correction
Introduction to corneal InlaysCorneal inlays are small artificial implants that are inserted into the eye via either a femtosecond laser-created pocket or corneal flap to improve near vision Three types of inlays are available :-1. KAMRA (Acufocus)
2.. Raindrop (formely Vue +PresbyLens , ReVision optics)
3.Flexivue Micro-lens (Presbia)
The Raindrop Inlay (corneal reshaping inlay) - It is a 2mm hydrogel corneal implant - Based on principle of multifocality- A 30 micron thick implant is placed under a 130-150 micron LASIK flap to change the corneal curvature of one eye to add near and intermediate focusing power .- This procedure is reversible and the implant can be removed.
How the raindrop in lay works
MicroLens Flexivue Hydrogel corneal microlens implanted after creating a
femtosecond flap. It is transparent , biocompatible and mimics a healthy
cornea made of hydrophilic polymer. Removal with reversible vision. Base on the multifocal (bifocal) principle 3mm wide , 15 micron thick , 0.15mm opening in the center to allow nutrient and fluid flow. Implanted in cornea at depth of 280-300 microns.
The bifocal design produces two images at fovea -One image results from combined refractive effects of area of cornea that surrounds the lens and central zone of lens -One image from peripheral zone of lensDisadvantage – pupil smaller than 3.0 mm = peripheral plus power of lens obstructed by iris.
KAMRA INLAY It utilizes a small aperture optics to increase the depth
of focus to allow only focused light rays to enter the eye .
It is 3.8 mm in diameter , 5 microns thick , 1.6 mm central aperture
The annulus is incorporated with black carbon particles and has 8,400 perforations of various sizes ,
This is designed to counter diffraction issues under mesopic settings and yet allow nutrient flow.
KAMRA inlay can provide up to 2.00 D of presbyopic correction.
Design of KAMRA implant
The KAMRA inlay is placed unilaterally in the patients non dominant eye in a corneal pocket and is centered over the visual axis.
Since the inlay works based on small aperture optics rather than a change in refractive power , improved near vision results remain immune to the progression of presbyopia , offering patients a lifetime of benefits.
Exclusion criteria
Prior corneal procedures (except LASIK and PRK)KeratoconousCataractMacular degenerationAmblyopia or strabismus Corneal degeneration or dystrophySevere dry eyePatient with unrealistic expectations
Thank you