CAIRS rings: biological intrastromal segments that flatten advanced keratoconus and avoid a transplant
Warsaw · Krakow · Vienna · Zurich
CAIRS (Corneal Allogenic Intrastromal Ring Segments) are segments of human corneal tissue implanted into a femtosecond-laser channel within the patient’s own cornea. They flatten the cone, reduce irregular astigmatism and restore lens tolerance or good vision with glasses. Unlike plastic rings they integrate with the tissue. SwissLaser offers the only structured CAIRS pathway for patients from Poland and neighbouring countries: assessment and follow-ups in Warsaw or Krakow, the procedure in our centre in Vienna.
CAIRS at a glance
- What it is: arc-shaped segments of decellularised donor corneal tissue (KeraNatural), 90–340 degrees long, placed in the corneal stroma at about 70–80% of its depth. Described by Dr. Soosan Jacob in 2018; in Europe the method is performed by a dozen or so centres.
- For whom: advanced keratoconus (stage II–IV), intolerance of rigid lenses, peripheral scars, a cornea too thin or too steep for cross-linking alone. Requirement: a clear corneal centre and at least 300–350 µm thickness at the implantation site.
- Effect: Kmax flattening by an average of 4–7 D, improvement of uncorrected and corrected visual acuity by 2–4 lines, better lens tolerance. The effect builds up over 3–6 months. If necessary the segments can be removed or exchanged.
- Price and pathway: 16,000 PLN per eye, including coordination of the procedure in Vienna, the ATOS femtosecond laser, tissue from a certified bank and follow-ups in Poland. Assessment with tomography 400 PLN. Prices and instalments.
- Safety: decellularised tissue causes no rejection; the risk of displacement and extrusion typical of PMMA rings is minimal with CAIRS. The procedure takes about 30 minutes under drop anaesthesia.
SwissLaser in numbers: cross-linking since 2007, trained by Prof. Theo Seiler in Zurich · over 25,000 refractive procedures by the lead surgeon · MS-39 and Anterion tomography · one team in Warsaw, Krakow, Vienna and Zurich · Google: 4.9 (Warsaw) and 5.0 (Krakow)
What CAIRS rings are and how they work
Intrastromal segments act mechanically: placed in the peripheral stroma, they add volume to the cornea outside the cone and “pull” its centre, flattening the apex. The longer and thicker the segment and the closer to the centre, the greater the flattening. Classic rings (Intacs, Keraring, Ferrara) are made of polymethyl methacrylate, a hard plastic. CAIRS is the same idea made of the material the cornea itself is built from.
The tissue comes from a certified tissue bank (KeraNatural, ready-made sterile segments), is free of donor cells, so the immune system does not recognise it as foreign. Over time the patient’s own corneal cells populate the segment. This allows it to be placed deeper and closer to the centre than plastic, achieving greater flattening with lower risk.
| Feature | CAIRS (human tissue) | Intacs, Keraring (PMMA) | Corneal transplant (DALK, PK) |
|---|---|---|---|
| Material | decellularised donor corneal tissue | hard polymer (plastic) | full or lamellar donor cornea |
| Biocompatibility | integrates with the cornea, no rejection | permanent foreign body | rejection risk 10–20% (PK), lower with DALK |
| Risk of displacement, extrusion | minimal | 3–10% in long-term follow-up | not applicable |
| Reversibility | yes, segment can be removed or exchanged | yes | no |
| Recovery | days to weeks | days to weeks | 12–18 months, sutures |
| Steroid drops | a few weeks | a few weeks | months or years |
| Use | advanced keratoconus with a clear centre | moderate keratoconus | central scars, very thin cornea |
More on the mechanics of segments in treatment of keratoconus.
Who CAIRS is for: indications and limits of the method
CAIRS is not a method for every keratoconus. It is the step between cross-linking and transplantation, for patients in whom merely halting the disease is not enough to see well.
- Advanced keratoconus (Kmax 52–65 D) with a clear corneal centre and thickness from 300–350 µm in the implantation zone.
- Intolerance of rigid or scleral lenses or no possibility of a stable fit.
- Cornea too thin or too steep for cross-linking alone: CAIRS first regularises the shape and CXL locks it in after 1–3 months.
- High irregular astigmatism and asymmetry (inferior cone): we place the segment where the cornea is steepest.
- Patients scheduled for transplantation who want to avoid or postpone it.
- Post-LASIK ectasia and keratoconus after failed PMMA rings (after their removal).
When CAIRS will not help
- dense scars in the corneal centre, after hydrops with scarring of the visual axis
- corneal thickness below 300 µm at the planned channel
- active inflammation, severe untreated dry eye
- the expectation of full acuity without glasses: CAIRS improves quality and regularity, the remaining refractive error is corrected later with an ICL lens or glasses
How CAIRS treatment works: assessment in Poland, procedure in Vienna, follow-ups in Poland
A procedure using human tissue is subject to regulations that in practice require a certified tissue bank and an infrastructure we have in our centre in Vienna. Everything else takes place in Warsaw or Krakow.
Assessment in Warsaw or Krakow
MS-39 tomography, Anterion, assessment of corneal thickness and clarity, simulation of segment position. Decision whether CAIRS is the right step and whether to combine it with cross-linking. 400 PLN, about 90 minutes.
Procedure in Vienna (about 30 minutes)
Drop anaesthesia. The Schwind ATOS femtosecond laser with cyclorotation compensation creates the channel at the planned depth and axis, without a blade. The KeraNatural segment is inserted into the channel and positioned. Our coordinator helps with travel and accommodation; usually 2 nights in Vienna.
First days
Check-up the next day in Vienna, return home. Mild discomfort, foreign-body sensation, blur for a few days. Antibiotic and steroid drops for 2–4 weeks.
Follow-ups in Poland and next steps
After one week, one month, three and six months in Warsaw or Krakow, each time with tomography. After 1–3 months cross-linking if planned; after a year of stability correction of the remaining refractive error with an ICL lens, glasses or contact lenses.
Recovery
- Days 1–3: discomfort, light sensitivity, blur; office work possible from day 3–5.
- Weeks 1–4: gradual improvement of corneal regularity; avoid rubbing the eye, swimming and contact sports.
- Months 1–6: the effect builds up, tomography documents the flattening; new glasses or lenses after 3 months.
- Permanently: yearly tomography check; the segments stay in the cornea and do not need replacing.
Results and safety of CAIRS according to publications and our experience
- Corneal flattening: in Dr. Jacob’s series (2018, 24 eyes) Kmax fell by about 5 D on average and uncorrected acuity improved in all patients; later publications (2021–2024) confirm flattening of 4–7 D.
- Visual acuity: improvement of best corrected acuity by 2–3 lines on average; some patients return to spectacle correction instead of scleral lenses.
- Tissue rejection: not described in the literature; the segments are decellularised.
- Complications: segment displacement below 2%, transient oedema or haze around the segment, rarely a need for repositioning. Infection below 1%.
- Reversibility: the segment can be removed; the cornea largely returns to its baseline state.
For me CAIRS is the biggest change in the treatment of advanced keratoconus since cross-linking. Instead of plastic we implant the tissue the cornea is made of, and we can place it where the effect is greatest. Many patients who had been told that only a transplant was left for them now have another way.
Dr. Victor Derhartunian, FEBO, FWCRS, one of the few surgeons in Europe performing CAIRS
Do I qualify for CAIRS?
Green light
- stage II–IV keratoconus with a clear corneal centre
- corneal thickness from 300–350 µm in the implantation zone
- intolerance of rigid lenses or unsatisfactory vision with lenses
- keratoconus too advanced for cross-linking alone
- age from about 16, any adult age
Amber light
- peripheral scars: their position relative to the planned channel decides
- previous hydrops without a central scar
- previous PMMA rings: we usually remove them and implant CAIRS after 3 months
- severe dry eye: treatment first
Red light
- dense central scars in the visual axis: lamellar transplant (DALK)
- thickness below 300 µm
- active inflammation or infection
Do you have corneal maps from another centre? Send them through the online pre-qualification and we will tell you whether CAIRS is an option before you travel for the examination.
Zapisz się na niezobowiązująca wizytę i konsultację, na której dowiesz się, jak możemy poprawić Twój wzrok.
What CAIRS costs and what the price covers
- CAIRS (KeraNatural): 16,000 PLN per eye.
- Included: tissue from a certified bank, the ATOS femtosecond laser, the procedure and next-day check-up in Vienna, travel coordination, all follow-ups in Poland in the first year.
- Not included: assessment with tomography 400 PLN, travel and accommodation in Vienna (we help with booking), cross-linking if planned as a separate step (3,600 PLN), a later ICL lens (11,000 PLN).
- Instalments: Santander Consumer Bank for patients resident in Poland; CAIRS is not covered by public insurance.
Frequently asked questions
Does CAIRS have to take place in Vienna?
At present, yes. A procedure using human tissue requires a certified tissue bank and an infrastructure we have in our Vienna centre. Assessment, planning and all follow-ups take place in Warsaw or Krakow; the stay in Vienna is usually 2 nights and the coordinator helps with the organisation.
Can my body reject CAIRS?
No. The segments are free of donor cells, so the immune system has nothing to recognise as foreign. No rejection has been described in the literature. Over time the patient’s own corneal cells populate them.
Does CAIRS replace cross-linking?
No, the methods complement each other. CAIRS improves the shape of the cornea, cross-linking halts the disease. In progressive keratoconus we combine them: first CAIRS, after 1–3 months CXL in Poland to lock in the new shape. In stable keratoconus CAIRS alone is enough.
How does CAIRS differ from Intacs and Keraring?
In material and safety profile. Intacs and Keraring are hard plastic that remains a foreign body in the cornea and in a few percent of cases migrates or extrudes. CAIRS is corneal tissue that integrates with the eye and can be placed deeper and closer to the centre, giving greater flattening.
Will I see without glasses after CAIRS?
The goal is a regular, stable cornea and avoiding a transplant, not full acuity without correction. Most patients see markedly better and return to glasses or more comfortable lenses. The remaining refractive error can be corrected after a year with an ICL lens.
Is the CAIRS procedure painful?
No. It is performed under drop anaesthesia and takes about 30 minutes. After the procedure there is a foreign-body sensation, light sensitivity and blur for a few days, relieved with drops.
How long is recovery after CAIRS?
Office work from day 3–5, sport after 2–4 weeks, stable effect after 3–6 months. Follow-ups in Poland after one week, one month, three and six months, then yearly.
Can CAIRS be removed?
Yes. The segment can be taken out or exchanged for another size, and the cornea largely returns to its pre-procedure state. This is an important difference from a transplant, which is irreversible.
How much does CAIRS cost and are there instalments?
16,000 PLN per eye including tissue, laser, the procedure in Vienna and follow-ups in Poland. Assessment 400 PLN. Instalments through Santander Consumer Bank for patients resident in Poland; public insurance does not cover the method.
Is CAIRS performed in teenagers?
Yes, usually from about age 16, when keratoconus is advanced and lenses are not tolerated. In younger patients cross-linking, which halts the disease, takes priority.
Zapisz się na niezobowiązująca wizytę i konsultację, na której dowiesz się, jak możemy poprawić Twój wzrok.
Related topics
- Keratoconus: guide to diagnosis and treatment
- Cross-linking: halting progression
- Keratoconus treatment prices
- ICL lenses after CAIRS and cross-linking
- Treatment of keratoconus
- Keratoconus treatment options
Medically reviewed by Dr. med. univ. (Vienna) Victor Derhartunian, FEBO, FWCRS, who has performed corneal cross-linking since 2007. Last updated: 6 September 2026.
Where we treat keratoconus
Tomography, cross-linking in every protocol, laser variants, ICL lenses and all follow-ups in both clinics; scleral lens fitting in Krakow; CAIRS implantation in our centre in Vienna. English-speaking care at every location.
SwissLaser Warsaw
ul. Kolejowa 1, 01-217 Warszawa · tel. +48 221 201 690
SwissLaser Krakow
ul. Kluczborska 15/U3, 31-271 Kraków · tel. +48 12 383 33 60
