CAIRS (corneal allogenic intrastromal ring segments) places thin curved strips of donor corneal tissue inside the cornea to flatten a keratoconus cone and improve focus. It does not halt keratoconus, which is the job of cross-linking. Mr Arthur Okonkwo, Consultant Ophthalmologist, offers it in Leeds in partnership with Leeds Teaching Hospitals.
It is aimed at mild to moderate keratoconus, where glasses blur and contact lenses have become hard to tolerate. His full list of Leeds corneal and refractive procedures is on the treatments page. Each eye takes about 20 to 30 minutes under numbing drops, as a day case.
Considering CAIRS for Keratoconus?
Book a CAIRS consultation with Mr Arthur Okonkwo to find out whether ring segments suit your cornea.
Prefer to call? 0113 460 1923, Monday to Friday, 9am to 5pm
What Is CAIRS?
Allogenic means the tissue comes from a donor, and intrastromal means the segments sit in the stroma, the thick middle layer of the cornea. Ring segments are short arcs placed towards the edge, away from the central zone you look through. Your own cornea stays in place, so it is far smaller than a corneal graft.
A femtosecond laser cuts fine tunnels in the cornea, and the segments are slid into them. They act like a brace, flattening the keratoconus cone and evening out astigmatism. The donor tissue is processed and sterilised, with the cells that drive rejection removed. CAIRS is often paired with corneal collagen cross-linking as a seperate procedure to prevent any further change in corneal shape.
Urgent Signs After Ring Segment Surgery: When to Get Help
Some grittiness and light sensitivity for a few days after keratoconus surgery is usual, but the signs below are not. Some red eye symptoms need 999.
| Your symptom | Possible cause | What to do |
|---|---|---|
| Pain, redness or discharge building after a few days | Possible infection | Same-day call to the eye team, or NHS 111 |
| Red eye with blurred, wavy or lost vision | Serious eye problem | Call 999 or go to A&E |
| Sudden, painful clouding of vision | Hydrops: fluid entering a very thin cornea | Same-day assessment through NHS 111 or A&E |
| A constant feeling that something is in the eye | Segment edge irritating the surface | Call 0113 460 1923 for an earlier review |
| Fever or low temperature, shivering, confusion or blotchy skin | Possible sepsis | Call 999 now |
An eye infection turning into sepsis is very unlikely, but know the adult signs of sepsis.
Conditions Mr Okonkwo Treats with CAIRS
- Mild to moderate keratoconus: the main use, once glasses no longer give clear sight. Progressive keratoconus usually also needs cross-linking.
- Pellucid marginal degeneration: thinning in a band near the lower edge of the cornea.
- Thinning after laser eye surgery: post-LASIK ectasia, a bulge that behaves like keratoconus. See laser vision correction for screening before laser.
- Contact lens intolerance: rigid lenses that rock or rub on a keratoconus cone.
- Irregular astigmatism: uneven focus from a distorted cornea.
- Severe keratoconus: the reshaping effect may be too small, so a corneal transplant is often discussed instead.
Treatment Options for Reshaping a Keratoconus Cornea
Mr Okonkwo plans the length, thickness and position of each segment from your scans. The combination you need depends on whether your keratoconus is still changing.
CAIRS on Its Own
Donor segments are placed without cross-linking, for keratoconus that scans show is already stable, for example after earlier cross-linking. It takes about 20 to 30 minutes per eye as a day case. Glare, halos and irritation are possible.
CAIRS Combined with Cross-Linking
Reshaping and strengthening are done on the same day or months apart, both as day cases, for keratoconus that is still progressing. Evidence for the combination is limited, so we prefer not to combine the procedures.
Cross-Linking Alone
If your sight is still acceptable with glasses or lenses, steadying the keratoconus may be enough. The cross-linking page covers its figures and risks; it is an outpatient treatment of under 30 minutes.
Not Sure Which Keratoconus Option Is Right for You?
Bring your most recent corneal scans and contact lens details for planning, and Mr Okonkwo will talk you through the options that suit your eye.
Prefer to call? 0113 460 1923, Monday to Friday, 9am to 5pm
Why Patients Choose Mr Okonkwo for CAIRS
CAIRS sits where corneal surgery and transplant science meet, and his training covers both.
- Training: Leeds and Manchester academic posts, then fellowships at Moorfields Eye Hospital and Melbourne’s Royal Victorian Eye and Ear Hospital.
- Clinics: private appointments at St James Laser Vision Clinic, and NHS and private clinics he leads at Leeds Teaching Hospitals NHS Trust.
- Qualifications: MBBS, FRCOphth, the laser and refractive surgery certificate, an MRes in transplant research and an Ulster University diploma.
- Academic post: Honorary Senior Lecturer, University of Leeds, with a PgCert in Medical Education.
- Publications: over 30 peer-reviewed papers on the cornea, transplantation and surgical innovation.
- Catchment: keratoconus patients come to Leeds from across Yorkshire and the North East.
How Strong Is the Evidence Behind CAIRS?
Plastic ring segments are the established version of this treatment, covered by NICE guidance HTG146 since 2007. There is no specific guidance yet for donor-tissue segments, so CAIRS has a shorter published track record.
Most plastic ring studies ran to 12 months. In them, segments worked loose in up to 20% of eyes, halos or glare affected 3% to 5%, and infection up to 3%. Donor tissue is chosen partly to reduce these problems.
Alternatives to CAIRS: Lenses, Plastic Rings, Cross-Linking or a Graft
Specialist contact lenses are the usual first step for keratoconus, improving sight only while worn without changing the cornea. Lenses made for keratoconus can suit steep corneas that standard lenses do not.
Plastic ring segments can be removed at a later date. Cross-linking alone suits keratoconus that is still changing but gives acceptable vision. Where lenses and rings cannot restore useful sight, a cornea transplant may be considered.
Your Ring Segment Pathway, Step by Step: Consultation, Planning and Appointment Day
- Referral: private patients can book directly, while NHS care starts with a GP or optician referral.
- First visit: 45 to 60 minutes for history, examination and corneal scans. Pupil-widening drops can blur sight for hours, so arrange a lift.
- Planning: Mr Okonkwo works out the size and placement of each segment, and whether cross-linking should come first or alongside.
- Treatment day: numbing drops, tunnels made with a femtosecond laser, segments placed in about 20 to 30 minutes per eye, then a rest in clinic.
- Follow-up: drops and clinic checks while the cornea settles over 3 to 6 months.
Recovery and Risks After Ring Segment Surgery
The surface heals within a few days, though grittiness and light sensitivity are common at first, and vision fluctuates for several weeks. The new corneal shape takes 3 to 6 months to settle, and only then are glasses or lenses re-prescribed.
Risk figures for donor segments are not yet published, so the table uses the NICE plastic ring figures as a guide.
| Treatment | Hospital stay | Example risk |
|---|---|---|
| Donor segments alone | Day case, home the same day | Halos or glare in 3% to 5% of eyes |
| Donor segments alone | Day case, home the same day | Infection in up to 3% of eyes |
| Donor segments with cross-linking | Day case or outpatient | Temporary corneal haze |
| Any ring segment | Day case | Segment working loose in up to 20% of eyes |
Where Mr Okonkwo Sees Patients About Ring Segments
Consultations take place at St James Laser Vision Clinic on Floor 4 of the Gledhow Wing.
| Location | Address |
|---|---|
| St James Laser Vision Clinic | Floor 4, Gledhow Wing, St James’s University Hospital, Beckett Street, Leeds LS9 7TF |
| Where the procedure is carried out | Floor 4, Gledhow Wing, St James’s University Hospital, Beckett Street, Leeds LS9 7TF |
| NHS clinics | Leeds Teaching Hospitals NHS Trust, by GP or optician referral |
Phone 0113 460 1923 on weekdays, 9am to 5pm. Evenings and weekends, use NHS 111; emergencies need 999.
FAQs About Donor Ring Segments
How long is recovery after CAIRS?
The surface usually heals in a few days. Vision fluctuates for several weeks, and the shape settles over 3 to 6 months.
When is it safe to drive after ring segment surgery?
Not on treatment day. Drive again once your sight meets the eyesight standard for drivers, reading a plate at 20 metres, and ask at your follow-up.
Is CAIRS major surgery?
No. It is a day-case procedure under numbing drops, about 20 to 30 minutes per eye, and your own central cornea stays in place.
Can keratoconus return or keep worsening after ring segments?
Yes. Ring segments reshape the cornea but do not strengthen it, so progressing keratoconus usually needs cross-linking as well.
What alternatives are there to donor ring segments?
Specialist contact lenses, plastic ring segments, cross-linking alone or, in severe disease, a corneal graft. Some people with stable keratoconus need no procedure.
Could my eye reject the donor segments?
Rarely. The processed tissue has its cells removed, and the segments lie outside the central zone, so rejection would not affect the main line of sight.
Do the segments stop keratoconus getting worse?
No. They improve the shape of the cone, while stopping keratoconus progressing is the aim of cross-linking.
Where does the donor tissue come from?
Corneal tissue from a deceased donor, processed and sterilised before use. People on the NHS Organ Donor Register can choose to donate their corneas.
Will I still need glasses or contact lenses?
Usually, yes. The aim is clearer focus and easier lens wear, with a new prescription once the shape settles at 3 to 6 months.
Am I awake for ring segment surgery?
Yes. Numbing drops are used, and you rest in the St James clinic before going home the same day.
Quick Info
What is it?
Donor corneal tissue segments set inside the cornea to reshape it
Who is it for?
Mild to moderate keratoconus and similar corneal thinning
How long does it take?
About 20 to 30 minutes per eye
Hospital stay
Day case under numbing drops, home the same day
Recovery
Surface heals within days; focus settles over 3 to 6 months
Ready to Get Started?
Book a consultation to discuss your symptoms and treatment options.
Book a CAIRS Consultation with Mr Arthur Okonkwo
Bring your most recent corneal scans and contact lens details for planning.
- Phone: 0113 460 1923, weekdays from 9am until 5pm
- Online: book a ring segment assessment or ask about suitability
Report a sore, red or blurring eye to the eye team the same day, or to your GP or NHS 111 out of hours. Sight that suddenly goes, or sepsis signs like confusion and blotchy skin, needs 999 or A&E.