Efficacy Of Corneal Allogenic Intrastromal Ring Segments (Cairs ) Without Or With Corneal Cross Linking In Patients With Progressive Keratoconus In African Population.

Corneal allogenic intrastromal ring segments (CAIRS),refers to mid-peripheral intrastromal transplantation of donor corneal stromal segments in patients with keratoconus.It is a less extensive procedure than deep anterior lamellar keratoplasty.It has become an advantageous solution that is reversible, and it does not take away the ability to do DALK or any other treatment modality in the future.It can be used synergistically with other treatment modalities such as topography-guided ablation or phakic IOL implantation.Incidence and severity of keratoconus is very much higher in African population.Furthermore,no studies are done so far to evaluate the efficacy and safey in african population.So, there was a need to conduct this study.

The Retrospective study was done at Lions Sightfirst Eye Hospital , Nairobi , Kenya by a single cornea specialist surgeon .

Inclusion criteria : 

1.All patients with stage 2 to 4 keratoconus (Amsler-Krumeich grading)

2.Previous cross linked patients or non crosslinked patients.

3.Age between 15 to 40 years .

Exclusion criteria: Previously operated keratoplasty in keratoconus,patients with thin corneas , corneal scar, dry eyes and any other ocular pathology other than keratoconus.

13 eyes with stage 2-4 keratoconus (Amsler-Krumeich grading) were included, CAIRS were trephined from donor cornea using a Jacob double-bladed trephine (3 different sizes depending on the stage of Keratoconus). Corneal ring segments were implanted into mid-depth femtosecond laser-dissected channels in the cornea in the 4.6-4.8 mm optic zone. It was followed by accelerated corneal cross-linking (A-CXL) in patients with progressive keratoconus-either conventional or contact lens-assisted CXL (A-CACXL).The main outcome measures were uncorrected visual acuity(UCVA),corrected distance visual acuity(CDVA),refraction,keratometry and pachymetry.Computed tomography scans  were also performed preoperatively as well as at 1,3 ,6 months postoperatively

Mean age was 20-40 years.Mean follow up was 7.46 ± 2.31 months (range 6-9 months ).

Mean uncorrected distance visual acuity (UDVA) showed significant improved by 2.56 ± 2.55 lines (P = 0.001); and spectacle‐corrected distance visual acuity improved by 1.33 ± 1.43 lines (P = 0.000) respectively.

Significant improvement was seen in sphere, cylinder, spherical equivalent, k1,k2,Higher Order Aberrations (HOA) (P < 0.01).

One eye continued to remain at the same UDVA.

All segments remained well positioned and no segment-induced complications were seen. None of the eye showed progression during the entire follow-up.

This study indicates that CAIRS with or without CXL is a simple, safe, and very effective option with good visual and refractive outcome for treating moderate keratoconus in African population.