Novel technique could help surgeons treating keratoconus, ectasia
Reviewed by Soosan Jacob, MS, FRCS, DNB
A novel technique to treat keratoconus that uses corneal allogenic intrastromal ring segments (CAIRS) was simple, safe, and effective in a small pilot study, said Soosan Jacob, MS, FRCS, DNB, director and chief, Dr. Agarwal’s Refractive and Cornea Foundation, and senior consultant, Cataract and Glaucoma Services, Dr. Agarwal’s Group of Eye Hospitals, Chennai, India.
Dr. Jacob developed the technique because the use of synthetic ring segments often has led to complications such as extrusion, migration, melt, corneal necrosis, and even infections necessitating corneal transplantation, she said. She wanted to find a way to decrease the incidence of these complications.
In the study, which was published in the Journal of Refractive Surgery,1 CAIRS trephined from donor cornea were then implanted into femtosecond laser-dissected channels in the cornea in 24 eyes (20 patients) with keratoconus. The CAIRS were used in the 6.5-mm optic zone. Dr. Jacob initially used ring segments (Intacs, Addition Technology) not as an implant but as an instrument to help get the CAIRS in, but later she found that the CAIRS pushed right in.
Afterward, accelerated corneal crosslinking (CXL) or contact lens-assisted CXL (another approach developed by Dr. Jacob, for crosslinking thin corneas) was performed.
Making the choice
The choice was made depending on each patient’s minimum corneal thickness. With contact lens-assisted CXL, a riboflavin-soaked bandage contact lens is placed on the eye to help increase the corneal thickness. The contact lens used is ultraviolet barrier-free.
The results in patients having accelerated CXL or contact lens-assisted CXL were similar in the study, Dr. Jacob said. Significant improvement occurred both for uncorrected distance visual acuity (mean, 2.79 ± 2.65 lines; range: 0 to 8 lines) and corrected visual acuity (mean, 1.29 ± 1.33 lines; range: 0 to 5 lines).
There also were significant improvements in spherical equivalent, simulated maximum keratometry, steepest keratometry, topographic astigmatism, anterior and posterior best fit spheres, mean power in the 3- and 5-mm zones, as well as other areas. No eye had any progression during the follow-up, which ranged from 6 to 18 months. All segments remained in position, and no segment-induced complications occurred.
“There is basically no disadvantage [with CAIRS],” Dr. Jacob said. “It’s biocompatible, easily available, effective, stable, safe, reversible, and adjustable.”
She looks forward to the creation of nomograms for CAIRS, femtosecond-cut CAIRS, eye bank-prepared segments, modified segments, and increased storage abilities.
Soosan Jacob, MS, FRCS
This article was adapted from Dr. Jacob’s presentation at Refractive Surgery Subspecialty Day at the 2018 meeting of the American Academy of Ophthalmology. Dr. Jacob has a patent pending for shaped corneal segments and the devices and processes used to manufacture them.
1. Jacob S, et al. Corneal Allogenic Intrastromal Ring Segments (CAIRS) combined with corneal crosslinking for keratoconus. J Refract Surg. 2018; 34:296–303.