Think of the cornea as a transparent rubber ball anchored around the edge where it meets the white part of the eye (the sclera). Bending or stretching the cornea in one direction causes an equal change in the opposite direction. Using the Visumax laser to create a tiny channel in the cornea 1mm in width, thin plastic semi-circular intra-corneal ring segments (ICR’s) are painlessly inserted into the channel to flatten the steeper parts of the cornea and steepen the flatter making the overall shape rounder.
The aim of ICR surgery is to make the cornea rounder and therefore to reduce the blur and ghosting caused by the irregular astigmatism associated with KCS. ICR surgery will not remove the need to wear glasses or contact lenses but should improve unaided vision and also improve clarity of vision with correcting lenses. We use Intacs® corneal implants which are gently placed into channels created by the Visuax laser to reshape your cornea, this can also be combined with CXL treatment to further reinforce the cornea and maintain the corrected shape. Corneal implants for the treatment of KCS were approved by NICE in 2007, the guidance can be downloaded here.
No, anaesthetic drops are used to numb the eye prior to the laser creating the channel. This process takes 7 seconds. The ring segments are then gently fed along the channel until they are in the correct position, you will feel gentle pressure on your eye during this part but no pain. Following surgery the eye will feel slightly gritty for a day or two.
Almost immediately. We will provide you with a course of eye drops to use after surgery. You can use screens and return to normal activities the next day. You must avoid rubbing or touching your eyes.
ICR surgery may be combined with CXL treatment during sequential procedures to limit recovery time and combine a therapeutic with a refractive procedure. When the eye has settled from ICR surgery and vision has stabilized fully, typically after 3 months, subsequent procedures may also be planned e.g. implantable collamer lens (ICL) surgery to further correct refractive error if required.
Risks of ICR surgery are low but in a small proportion of cases improvement can be unpredictable because every keratoconic cornea is different, around 70% of patients will experience an improvement in vision but others may not even if the corneal shape is made rounder. Infection is rare and further surgery e.g. repositioning the rings is also uncommon. As ICR surgery does not involve removal of tissue the procedure is reversible by removal of the rings.
ICR surgery for KCS is approved by the National Institute for Health and Care Excellence for which guidance IPG227 can be downloaded here.
Intacs® are made from polymethylmethacrylate or PMMA, a type of inert plastic that has been used in many types of medical devices including intraocular lenses for over 40 years.
ICR surgery is designed to be a permanent procedure although the ring or rings can be removed if desired. Should corneal transplant surgery be required at a later date, previous ICR surgery is unlikely to affect the outcome.
Yes, although they are transparent, the small arcs of the ICR are visible.
Yes, the ICR(s) can be removed from the cornea through the same channel.
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