Treatment
CAIRS – Allogenic Corneal Rings (KeraNatural)
CAIRS uses sterilised human donor corneal rings (KeraNatural), implanted with a femtosecond laser, to reshape the cornea and improve vision in keratoconus — a minimally invasive, tissue-friendly alternative to corneal transplant.
Overview
Understanding the Procedure
Corneal Allogenic Intrastromal Ring Segments (CAIRS) — using the KeraNatural™ allograft — is a minimally invasive treatment for keratoconus and corneal ectasia. Small, semicircular rings made from sterilised human donor corneal tissue are implanted within the cornea to reshape it: flattening the cone, reducing astigmatism and improving vision.
The cornea is the clear window at the front of the eye and provides about two-thirds of its focusing power. It can be weakened by eye rubbing and by inflammation — often linked to asthma, eczema or hay-fever — as well as by a naturally thin cornea or previous refractive surgery. This weakening leads to ectasia such as keratoconus, where the cornea bulges and distorts, blurring vision in a way that glasses and soft contact lenses cannot fully correct.
KeraNatural™ is a sterilised, tested allograft corneal collagen ring supplied by the Vision Gift Eye Bank, which is accredited by the Eye Bank Association of America. Because the ring is made of corneal tissue rather than plastic, it is well tolerated within the cornea and avoids many of the complications associated with synthetic ring segments.
Unlike a corneal transplant (keratoplasty), CAIRS reshapes the cornea without replacing any of the patient's own tissue. It is a lower-risk, minimally invasive procedure with no sutures to remove and a shorter recovery — and it does not require a full donor cornea.
Benefits
What This Means for You
- Reshapes the cornea to flatten the cone and reduce astigmatism
- Uses natural donor corneal tissue rather than plastic rings
- Minimally invasive, ~15-minute day-case procedure under drops
- No sutures and no suture removal, unlike corneal transplant
- Lower risk and faster recovery than keratoplasty
- Can be combined with collagen cross-linking for added stability
- May reduce dependence on glasses or contact lenses
Our Approach
Consultant-Led Care
Miss Tina Khanam is a corneal specialist who uses femtosecond laser technology to create a precise, smooth channel within the cornea before placing the donor rings. This is more accurate than the traditional mechanical technique and is associated with better results and fewer complications.
The procedure is performed as a day case under topical anaesthesia — numbing drops rather than injections — and typically takes around 15 minutes. Where appropriate, CAIRS can be combined with collagen cross-linking to both reshape and stabilise the cornea.
Suitability
Is This Right for You?
- Patients with keratoconus or corneal ectasia
- Those whose vision can no longer be corrected with glasses or soft contact lenses
- Patients intolerant of rigid or scleral contact lenses
- People wishing to avoid or defer a corneal transplant
- Post-refractive surgery ectasia
Common Questions
Frequently Asked Questions
A corneal transplant (keratoplasty) replaces all or part of the cornea with donor tissue and requires sutures that stay in for at least six months. CAIRS instead places small donor-tissue rings within the cornea to reshape it, without removing any of your own tissue. It is minimally invasive, has no sutures to remove, carries a lower risk of complications and has a much shorter recovery.
CAIRS is usually performed under topical anaesthesia (numbing drops). You are awake but should feel no pain. The surgeon creates a channel in the cornea — at our clinic using a femtosecond laser for precision — and places the donor rings within it. The procedure takes about 15 minutes, and most patients return to normal activities within a day or two.
The aim is to improve and stabilise vision and to reduce astigmatism as much as possible, but it is not possible to eliminate astigmatism entirely. Vision recovers gradually over several weeks or longer, and some patients still benefit from glasses or contact lenses afterwards.
KeraNatural/CAIRS is a newer procedure and is not reimbursed by most insurance companies, although corneal transplantation is generally recognised. Because CAIRS uses donated, transplanted corneal tissue, some insurers consider it in the same category as keratoplasty. We will discuss fees and any insurance questions at your consultation.
We advise taking about a week off work, though visual recovery can take longer. Soft contact lenses can usually be resumed as normal once vision settles; a gas-permeable or hard lens may need around a month before it can be worn comfortably again. Your contact lens practitioner may need to be involved before resuming lens wear.
Pregnancy and breastfeeding are considered contraindications, as the effects of treatment in pregnancy — and of pregnancy on the result — are not known. If you become pregnant after treatment, there is no evidence that CAIRS affects pregnancy or any of the sight and scanning tests performed.
Quick Facts
Duration
Approximately 15 minutes per eye
Anaesthesia
Topical anaesthetic drops — no needle injection
Recovery
Most activities within 1-2 days; around a week off work; vision recovers over several weeks
Pain Level
Mild discomfort
Ready to Learn More?
Take our quick suitability quiz or book a consultation to discuss your options with your consultant.
Related
Understanding Your Condition
Learn more about the conditions this treatment addresses. Knowledge is the first step toward confident decision-making.
Take the Next Step
Book a consultation to discuss CAIRS – Allogenic Corneal Rings (KeraNatural) with your consultant. Transparent advice, no pressure, and a personalised plan for your vision.