A 56-year-old woman came to Centro Láser with forme fruste keratoconus in both eyes and visually significant cataract. Her right eye saw 20/400 with her best correction. The left eye, only counting fingers. On the Pentacam, her maximum keratometry reached 56.1 diopters in the worse eye, over a cornea of only 426 microns. Conventional cataract surgery options did not work in that scenario: an irregular cornea makes intraocular lens calculation imprecise and makes the view inside the operating room a cloudy window. We proposed a two-stage strategy: first regularize the cornea with human tissue segments (CAIRS), then operate on the cataract with an intraocular lens. To our knowledge, this is the first reported case of that combination in the literature.
The result: the patient went from seeing 20/400 and counting fingers to 20/20 in the dominant eye and 20/25 in the fellow eye, with J1 near vision bilaterally. This case, authored by Dr. Martha Aguirre (cornea and refractive surgery fellow at Centro Láser) together with Dr. Francis Núñez and myself, was presented at the Dominican Congress of Ophthalmology in Baní and at the Bascom Palmer Eye Institute Inter-American Course in 2026. What follows is the full journey, and why we believe human tissue changes what can be done inside an eye with an irregular cornea.
Why cataract in a keratoconus eye is a surgical challenge
An eye with keratoconus and cataract confronts the surgeon with two simultaneous problems. The first is optical: the irregular cornea distorts light before it reaches the retina, which distorts the patient's vision but also the surgeon's view through the surgical microscope. The second is computational: standard formulas for calculating intraocular lens power assume a regular cornea, and when the cornea is conical, the calculation becomes an approximation.
The practical consequence is that many patients with keratoconus and cataract end up with two bad options. If the cataract is operated without addressing the cornea, final vision is limited by residual corneal distortion. If the keratoconus is addressed first with a transplant, the patient is exposed to major surgery with years of healing before the cataract can be touched.
Synthetic rings (ICRS) have offered, for decades, a way to regularize the cornea without resorting to transplantation. What changes with human tissue segments (CAIRS) is the material, and that change has consequences that became evident in this case.
What CAIRS are and why they matter in this scenario
CAIRS (corneal allogenic intrastromal ring segments) are pieces of human donor corneal tissue inserted into tunnels created with a femtosecond laser in the corneal periphery. Their function is the same as synthetic rings: to flatten the central zone and regularize the shape. I previously wrote a complete guide on CAIRS as a treatment for keratoconus where I explain the technique in detail. I also recently documented a case of CAIRS inside a previous penetrating keratoplasty as another innovative application.
The material difference compared to synthetic ICRS (made of PMMA) becomes decisive in the operating room when intraocular surgery is required. A plastic ring, no matter how transparent, scatters and reflects light from the surgical microscope in a way that alters visualization of the anterior segment. A segment of human corneal tissue integrated with the patient's stroma behaves optically like the cornea itself.
The original technique was described by Soosan Jacob in 2018 (published in the Journal of Refractive Surgery). The most recent meta-analysis, published by Friedrich et al. in American Journal of Ophthalmology (2025), reviewed 14 clinical studies with 442 eyes treated with CAIRS and reported a severe complication rate of 0.2%. Those numbers support the overall safety profile, although the initial reports did not cover the specific scenario of concurrent cataract.
Recent literature includes two cases in adjacent but different contexts. Ali et al. (2023) described cataract surgery in a patient with previous ICL and CAIRS, a triple combination that adds complexity because of phakic lens explantation. A report published in Journal of Cataract & Refractive Surgery (2025) documents the reverse sequence, phacoemulsification first followed by CAIRS in the same session, in a context of senile cataract with ectasia. This case is different in two dimensions: there is no prior ICL, and the order is CAIRS first in a standalone session, phacoemulsification with IOL in a later session after confirming corneal stabilization. That sequence is what makes the "to our knowledge" qualifier useful in the novelty claim.
The case: 56-year-old woman, bilateral keratoconus and cataract
The patient arrived with a history typical of late keratoconus: years living with limited vision, refractive surgery never recommended because of her thin corneas, and now cataract settling on top of the picture.
Preoperative evaluation
On examination we found the following:
| Preop BCVA | KMAX | Pachymetry | |
|---|---|---|---|
| OD | 20/400 | 51.3 D | 454 µm |
| OS | Counting fingers | 56.1 D | 426 µm |
The Pentacam confirmed typical forme fruste keratoconus in both eyes, with the left eye more advanced. Both lenses had visually significant opacities that warranted cataract surgery. But the standard intraocular lens calculation over a cornea with 56 diopters of maximum keratometry and 426 microns of thickness is an exercise in approximation, not in precision.
The surgical decision
We considered several options. Cataract surgery alone would have left the patient with her irregular corneal astigmatism intact and an unpredictable residual refractive error. A corneal transplant would have exposed her to years of recovery before the cataract could be operated. The option we chose, CAIRS first and then cataract surgery with intraocular lens, aimed at two goals simultaneously: regularize the cornea so the lens calculation would be reliable, and take advantage of the integrated transparent tissue to see well during intraocular surgery.
We started with the left eye, the worse one. That is a decision many surgeons make in reverse, operating the better eye first, but when one eye is at counting fingers and the other still holds 20/400, the marginal gain of intervening the worse eye is much larger.
Phase 1: CAIRS to regularize the cornea
The CAIRS implant was performed as a standalone procedure, separate from cataract surgery. The technique followed the scheme described by Jacob and validated in our practice:
- A single inferior segment, 500 microns wide and 140 degrees long
- Tunnel created with femtosecond laser at 50% stromal depth
- Donor corneal tissue segment pre-cut with a microkeratome and trimmed to exact length
- Riboflavin used to help visualize the segment during insertion
There were no intra- or postoperative complications. One month after surgery, evaluation showed changes that justified moving to the second phase.
Results at one month post-CAIRS
| BCVA | Corneal astigmatism | |
|---|---|---|
| OD | (unchanged, still pending its own phase 1) | 1.8 D |
| OS | 20/80 (from counting fingers) | 0.3 D |
Corneal regularization was remarkable: the corneal astigmatism of the operated eye dropped to 0.3 diopters, a value practically insignificant from an optical standpoint. With that new cornea, the intraocular lens calculation was now reliable.
Phase 2: cataract surgery with the CAIRS segment already integrated
This is the phase of the case where human tissue showed its clearest advantage. Cataract surgery was performed with the divide and conquer technique, a standard phacoemulsification approach. The procedure itself was routine.
What was not routine was the visualization. Throughout the surgery, the CAIRS segment integrated in the cornea behaved optically as the patient's own tissue. There were no reflections or light scatter that altered the surgeon's view of the lens and capsule. That functional transparency is the practical difference, in the operating room, between a human tissue segment and a synthetic one.
The lens decision
For the left eye, now with corneal astigmatism regularized to 0.3 D, we implanted a monofocal intraocular lens. For the right eye, which retained 1.8 D of corneal astigmatism after its own CAIRS phase, we chose a toric lens to correct it simultaneously.
The asymmetric lens strategy was deliberate: we designed a mini-monovision, with the dominant eye focused at distance and the non-dominant eye slightly closer. In corneas regularized with CAIRS, mini-monovision works well because the cornea stops being the limiting factor.
Final results
At the end of the full postoperative period the numbers settled as follows:
| Distance UCVA | Near vision | |
|---|---|---|
| OD (dominant) | 20/20 | J1 |
| OS (non-dominant) | 20/25 | J1 |
The patient went from needing assistance to function (counting fingers in one eye, 20/400 in the other) to reading without glasses with bilateral J1 and seeing 20/20 at distance in her dominant eye. The functional jump is the type of outcome that in an eye with advanced keratoconus and bilateral cataract was not achievable just a few years ago.
Why this case matters technically
Two reasons. The first is sequence: the combination of CAIRS followed by phacoemulsification with intraocular lens gave us the opportunity to treat two distinct pathologies, irregular cornea and cataract, in the same eye without resorting to a transplant. The second is material: the optical transparency of the integrated human tissue facilitated intraocular surgery in a way synthetic segments would not have allowed.
That second point is what most changes the clinical conversation. In corneas treated with synthetic ICRS, subsequent cataract surgery becomes more demanding because of compromised visualization. In corneas with CAIRS, the surgeon operates as if the implanted tissue were part of the native cornea. For a field that will increasingly have to combine corneal procedures with anterior segment surgery, that difference is structural.
Does this apply to every patient with cataract and keratoconus?
No. The candidacy criteria are specific:
- Documented and stable keratoconus (not in active progression without prior crosslinking)
- Visually significant cataract that warrants surgery
- Sufficient corneal thickness to accommodate CAIRS segments at 50% depth (typically a minimum of 400 µm)
- Corneal endothelium with adequate reserve
- Patient expectations aligned with the need for two separate surgical stages
Before proposing this combination, the protocol includes Pentacam, anterior segment OCT, aberrometry, biometry with a specific formula for irregular corneas, and an endothelial evaluation. If any of those studies shows risk, the sequence is not recommended.
Frequently asked questions
Why not operate the cataract first and the cornea later?
Because cataract surgery over an irregular cornea produces imprecise intraocular lens calculations, and the refractive outcome is limited from the start. By regularizing the cornea first with CAIRS, the lens calculation becomes reliable and the final visual outcome depends on one fewer component. In addition, visualization during intraocular surgery improves, which also matters for the safety of the procedure.
Can everything be done in a single surgery?
In this case we chose two separate stages because we wanted to wait for corneal stabilization after CAIRS before calculating the definitive intraocular lens. A combined procedure is theoretically possible, but it gives up the precise measurement of the stabilized cornea, which is precisely the advantage that justifies doing CAIRS first.
What type of intraocular lens is used?
It depends on the residual corneal astigmatism after CAIRS. When astigmatism ends up very low (such as the 0.3 D in one of this patient's eyes), a monofocal lens is sufficient. When a significant residual remains (1.8 D in the other eye), a toric lens corrects that astigmatism while also treating the cataract. Multifocal lenses are also possible over well-regularized corneas, although the criterion is conservative.
How much time between CAIRS and cataract surgery?
In our experience, a minimum of one month for the stroma to integrate the segments and the topography to stabilize. For this patient we waited one month between the two stages for the left eye and a similar time for the right eye.
Is it reversible if something goes wrong?
CAIRS are reversible: if needed, the segments can be removed and the cornea largely returns to its preoperative shape. The intraocular lens, once implanted, is a more permanent decision, although it can also be explanted if an extreme case were to require it.
What this case makes clear
When a corneal pathology combines with cataract, the choice of material matters. Human tissue in the cornea not only regularizes the shape, it also allows subsequent intraocular surgery to be performed with the same visual cleanliness as in an eye without corneal pathology. That is a data point a case report can show and that a synthetic ring would hardly match.
If you have keratoconus and have been told your cataract is a complicated surgery, it is worth an evaluation with a team that works with CAIRS. The combination does not apply to every case, but it exists as a real option for a well-defined subgroup.
About the author
Dr. Juan F. Batlle Logroño is an ophthalmologist specialized in cornea and refractive surgery. A medical graduate of Tulane University and Fellow of the Bascom Palmer Eye Institute, he is Co-Director of CCCRP and of the Dominican Republic Cornea Bank. He practices at Centro Láser, an ophthalmology institution with more than 50 years of history in the country, where he leads the CAIRS program and trains fellows in cornea and refractive surgery. This case was operated and presented by his team, led by Dr. Martha Aguirre, together with Dr. Francis Núñez.
Legal notice
This content is for educational and informational purposes. It does not replace professional ophthalmologic consultation, diagnosis, or treatment. Each case of keratoconus and cataract is different and requires individualized evaluation. The outcomes described correspond to a specific patient and may vary depending on each person's clinical conditions.
References
- Jacob S, Patel SR, Agarwal A, et al. Corneal Allogenic Intrastromal Ring Segments (CAIRS) Combined With Corneal Crosslinking for Keratoconus. Journal of Refractive Surgery. 2018;34(5):296-303. DOI: 10.3928/1081597X-20180223-01. PMID: 29738584.
- Friedrich M, Auffarth GU, Soiberman U, Augustin VA, Khoramnia R, Son HS. Visual and Topographic Outcomes After Corneal Allogeneic Intrastromal Ring Segments for Keratoconus: A Systematic Review and Meta-Analysis. American Journal of Ophthalmology. 2025;276:81-91. PMID: 40157443.
- Ali AA, Saenz B, Nasser T. Cataract Surgery following Corneal Allogenic Intrastromal Ring Segments and Implantable Collamer Lens. J Clin Transl Ophthalmol. 2023;1(3):72-78. DOI: 10.3390/jcto1030009.
- Immediate sequential corneal allogeneic intrastromal ring segment transplantation and cataract surgery. Journal of Cataract & Refractive Surgery. 2025.
- Aguirre M, Batlle JF, Núñez F. Phaco-IOL Post CAIRS. Presented at the Dominican Congress of Ophthalmology (Baní/AddoCorp) and at the Bascom Palmer Eye Institute Inter-American Course, 2026.
Last updated: April 17, 2026
