October 09, 2025
1 min read
Key takeaways:
- Characteristics or placement of CAIRS can be adjusted after initial surgery.
- Patients who lost lines of vision after the first surgery regained them after adjustment.
Adjustment procedures can help improve suboptimal results after implantation of corneal allogeneic intrastromal ring segments, according to a study in Journal of Refractive Surgery.
Soosan Jacob, MS, FRCS, DNB, of Dr. Agarwal’s Eye Hospital and Eye Research Centre, India, and colleagues wrote that using corneal allogeneic intrastromal ring segments (CAIRS) for the treatment of keratoconus and other ectasias can improve uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA).
“In certain cases, however, the effect of the CAIRS may be suboptimal, and this may be improved by adjusting the characteristics of the CAIRS or its placement,” they wrote.
Jacob and colleagues conducted a retrospective interventional case series of 13 eyes of 13 patients.
If the arc length of the implant was too long, surgeons shortened the corresponding zone to relieve excess corneal flattening. If it was too short, they cut and inserted an additional segment.
In patients with excess flattening, surgeons removed the implant, cut it to the desired thickness or width, and reinserted it. They implanted an additional segment if the patient required additional flattening.
They also made adjustments to the placement of CAIRS based on the optical zone and imaging.
Compared with baseline, the mean improvement to UDVA and CDVA after CAIRS implantation was 1.5 ± 3 lines of vision and 0.2 ± 1.5 lines of vision, respectively. Two patients lost three lines of UDVA, and five patients lost 0.5 to three lines of CDVA.
After adjustment compared with baseline, the mean improvement in UDVA was 3.6 ± 3 lines of vision, and the mean improvement in CDVA was 1.15 ± 1.6 lines of vision. Patients did not lose any lines of vision after adjustment, and patients who lost lines of vision after the initial implantation regained them after adjustment.
“CAIRS implantation is a procedure that lends itself well to adjustments,” Jacob and colleagues wrote. “It is therefore possible to try to improve a suboptimal result obtained following CAIRS surgery by performing an adjustment procedure.”
Perspective
In the August 2025 issue of Journal of Refractive Surgery, Jacob and colleagues demonstrate that postoperative adjustment of corneal allogeneic intrastromal ring segments (CAIRS) can effectively rescue suboptimal outcomes in keratoconus and ectasia. In routine practice, even with careful nomogram-based planning, corneal biomechanics may be unpredictable, and initial CAIRS implantation can sometimes lead to inadequate or excessive flattening. This study shows that adjustments — whether altering arc length or thickness or repositioning within the optical zone — are not only feasible but can restore or improve vision without compromising safety. Importantly, patients who lost lines of acuity after the first intervention regained them after adjustment.
For the practicing surgeon, the key takeaway is that CAIRS should not be viewed necessarily as a static procedure. Careful postoperative assessment with topography and anterior segment OCT allows identification of malpositioned or suboptimal segments, and timely adjustment can refine the effect. This adjustability can defer or even obviate the need for keratoplasty in selected patients. While larger studies are needed to formalize adjustment protocols, the concept encourages a shift toward staged, personalized management of keratoconus or ectasia in the clinical setting.
In summary, CAIRS does not have to be a one-time intervention — its postoperative adjustability allows surgeons to refine outcomes, restore vision and delay keratoplasty in patients with keratoconus and ectasia.
Disclosures: Yoo reports no relevant financial disclosures.
Sources/Disclosures
Source:
Jacob S, et al. J Refract Surg. 2025;doi:10.3928/1081597X-20250515-05.
Disclosures:
Jacob reports having licenses through Madhu Instruments Pvt. Ltd., consulting for Lions World Vision Institute and Ziemer, and holding a patent for special trephines, devices and processes used to create these segments and for modified and shaped CAIRS segments. Please see the study for all other authors’ relevant financial disclosures.
