CAIRS
Allograft ring segments for keratoconus
Corneal allogenic intrastromal ring segments, from two international eye banks and supplied in South Africa. CAIRS offers an alternative to corneal transplantation for selected patients with keratoconus.
Published data
The South African picture
In the eThekwini Health District between 2011 and 2014, keratoconus accounted for 64% of elective penetrating keratoplasty indications. Two thirds of that waiting list, 67%, was under 41 years old.
Over three years, 20% of the list received a graft. Of those who did, the middle half waited between 143 and 520 days. A quarter waited longer than that.
Khan M, Visser L, Mahomed S. African Vision and Eye Health. 2015;74(1):a299
Local donation was falling at the same time. Between 2002 and 2016, corneal donors in South Africa fell from 565 a year to 89, and transplants using locally donated corneas fell 85.5%, from 1,049 a year to 152.
York NJ, Tinley C. South African Medical Journal. 2017;107(8):12482
The procedure
CAIRS
Corneal Allogenic Intrastromal Ring Segments.
Donor corneal stroma is shaped into arcs or rings and implanted into a channel in the recipient’s stroma to flatten the cone.
The segments are allograft rather than PMMA.
In the pilot series that introduced the technique, 24 eyes of 20 patients treated with CAIRS combined with cross-linking gained a mean of 2.8 lines of uncorrected and 1.3 lines of corrected distance visual acuity at a mean follow-up of 12 months, with significant improvement in keratometry, spherical equivalent and topographic astigmatism. No eye progressed during follow-up and no segment-induced complications were seen.
Jacob S, Patel SR, Agarwal A, Ramalingam A, Saijimol AI, Raj JM. Corneal Allogenic Intrastromal Ring Segments (CAIRS) Combined With Corneal Cross-linking for Keratoconus. Journal of Refractive Surgery. 2018;34(5):296-303. doi:10.3928/1081597X-20180223-01
Longer follow-up has since been published. A prospective series of 62 eyes reported improvements in visual acuity, refraction and keratometry sustained to three years, with no major intraoperative or postoperative complications.
Keskin Perk FFN, Tanriverdi C, Karaca ZY, Tran KD, Kilic A. Long-Term Results of Sterile Corneal Allograft Ring Segments Implantation in Keratoconus Treatment. Cornea. 2025;44(4):475-482. doi:10.1097/ICO.0000000000003592
An earlier series of 44 eyes implanted to the Istanbul nomogram reported significant improvement in uncorrected and corrected visual acuity, spherical equivalent and keratometry at six months, with no major complications.
Haciagaoglu S, Tanriverdi C, Keskin FFN, Tran KD, Kilic A. Allograft corneal ring segment for keratoconus management: Istanbul nomogram clinical results. European Journal of Ophthalmology. 2023;33(2):689-696. doi:10.1177/11206721221142995
If you already implant synthetic ring segments, this is the same procedure with a different material.
Specification
Two allograft options
Evolution Vision supplies both allograft ring segment lines available in South Africa, from two international eye banks.
KeraNatural®
OptiGraft®
Supplied by
Vision Share
Lions World Vision Institute
Supplied as
Arc, ring
Arc
Geometries
Arc, ring
Concentric, tapered, crescent
Thickness
Full and split thickness
Thickness 550 µm
Widths
Approximately 1 mm
0.50 mm, 0.75 mm, 1.0 mm, 1.5 mm, 2.0 mm
Preparation
Processed from donor corneal tissue, electron beam sterilised
Processed from donor corneal tissue, femtosecond laser-cut, electron beam sterilised
Storage
Two years
Room temperature, up to two years
Listed alphabetically.
Instruments
CAIRS Instruments
The RUMEX CAIRS Treatment Set covers every stage of the procedure, from marking and fixation to tunnel creation and segment implantation. The set holds 16 instruments and comes with a sterilisation tray. Tunnel creation is manual, so no femtosecond laser is needed. The dissector range sizes the tunnel to the individual cornea, including atypical anatomy. Most instruments are titanium, and the diamond knife has a natural diamond blade.
Stabilising and guiding
Creating the tunnel
Implanting the segment
The full set brochure
Manufactured by
