Intracorneal rings, or ICRs, are microthin curved implantable devices made of polymethylmethacrylate (PMMA) that are used to manage keratoconus. Please read ‘Keratoconus’ leaflet for more information.
By placing the rings inside the cornea, the steep cornea can be flattened and supported. Depending on the pattern and severity of the keratoconus, one or two rings may be implanted. You should understand that the aim of implanting ICRs is mainly to strengthen and stabilize, but not cure, your progressively weak keratoconus cornea. Although better vision is not the aim of ICRs, you may notice partial improvement but glasses or contact lenses may be needed to further improve vision.
To be a candidate, you should have a confirmed keratoconus diagnosis, age above 14 years, not too advanced keratoconus, not too thin corneas, and no other eye pathology especially allergy or excessive dryness. Also, you should be realistic with your expectations and willing to accept the potential risks associated with this procedure.
This out-patient procedure is simple and relatively painless, usually lasting 20-30 minutes. With anaesthetic drops, a tunnel is created by femtosecond laser according to individual pre-operative measurements. The ring(s) will then be inserted. If needed, a tiny suture may be used to close the opening. A bandage soft contact lens is placed.
To aid in proper sterile healing, you are advised to use antibiotic, anti-inflammatory and lubricant eye drops as well as eye shields that should be worn at bedtime for the first week. You may experience some discomfort, burning, foreign body sensation, unstable vision, glare, and haloes up to 3 months. The contact lens will be removed by the surgeon within the next day or two, while the suture (if any) will remain up to 1 month. Showering is to be avoided for a couple of days. You should be able to return to normal activities after a few days’ sick leave but rubbing your eyes must be avoided.
ICR implantation as any surgery can have complications, which should be considered before making a decision. These can be technical, such as failure to implant the rings, decentration of the rings or ring extrusion through the wound. You may notice dry eyes, uncomfortable glare and haloes. Delayed healing, unstable keratoconus, infections, inflammations, etc. are rare but possible complications. In some cases, the rings may need to be removed or replaced.
Note: Due to the progressive nature of keratoconus, most patients undergoing ICR implantation will also undergo corneal cross-linking (CXL, see ‘Corneal cross-linking’ leaflet for more information) after some months.Future procedures to further manage keratoconus are possible, such as corneal grafting. Further procedures will be charged accordingly.