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From CAIRS to CTAK, UT-DSAEK and More–Updates in Corneal Surgery Abound at ASCRS 2024

On Day Two at the 2024 Annual Meeting of the American Society of Cataract and Refractive Surgery (ASCRS 2024), experts like Dr. Winston D. Chamberlain, Dr. W. Barry Lee and Dr. Marjan Farid convened to share the latest advances in technology and approaches in corneal surgery, delving into corneal tissue addition keratoplasty (CTAK) for keratoconus, intracanalicular steroid inserts, artificial corneas and more.

Keratoconus surgical innovations

Dr. Brandon D. Ayres from The Wills Eye Institute in Pennsylvania (USA) began by sharing the pros and cons of the traditional combination of intracorneal ring segments (ICRS) and corneal cross-linking (CXL) in keratoconus treatment.

“These are procedures that we know, and they seem to do well together, “ he said, “The bad thing is that ICRS can have complications like extrusion, infection and segment migration.”

To avoid the risks associated with the implantation of synthetic ICRS, corneal allogenic intrastromal ring segments (CAIRS) was developed using corneal tissue. Popularized by Dr. Soosan Jacob, CAIRS offers greater customizability. “They can be inserted in a variety of ways, they can have differential thickness, and they can even make ‘cornea jerky’,” added Dr. Ayres. “They call it the cornea jerky technique. They’ll dehydrate the tissue so it’s a little bit dryer and a little bit stiffer, which makes it easier for the surgeon to insert into the eye,” he explained.

The latest in keratoconus surgery, however, is CTAK. The procedure uses a custom-shaped irradiated corneal tissue, which is added to the patient’s cornea through a channel created by the femtosecond laser and induces reshaping of the cornea for improved vision.

Dr. Ayres emphasized that early detection is still critical. “Collagen processing early is the most important thing, and then we can layer other procedures on top of that. Additive technologies like CAIRS and CTAK are great for mild, moderate and severe cases,” explained Dr. Ayres.

New techniques for pterygium

From CAIRS to CTAK, UT-DSAEK and More–Updates in Corneal Surgery Abound at ASCRS 2024
Dr. Michelle K. Rhee shares her latest research results on intracanalicular steroid delivery

Dr. Michelle K. Rhee of the Icahn School of Medicine at Mount Sinai in New York (USA) started off her presentation by discussing the tendency for clinicians to underestimate the impact of pterygium surgery. 

Through patient testimonials, Dr. Rhee underscored the profound impact of pterygium surgery on patients’ confidence and quality of life, challenging the notion that only severe cases warrant surgical removal. “The more I’ve done it, the more I’ve come to appreciate how much of a positive impact it can make on patients’ lives,” Dr. Rhee shared.

Discussing surgical techniques, Dr. Rhee doesn’t argue with the historical gold standard of incision with conjunctival autograft and the use of fibrin glue, emphasizing their efficacy over decades. What she does contend is the lack of consensus regarding postoperative steroid management, acknowledging the need for further research in optimizing dosage and duration.

“We know that prolonged course of service is important, but there is not a consensus on optimal dose, frequency and duration of use.” Dr. Rhee explained.  

She discussed novel approaches to postoperative steroid delivery, such as intracanalicular inserts. She presented her latest research comparing different delivery methods which found that the inserts may reduce medication burden for patients who require prolonged postoperative steroid therapy.1 

She also introduced the concept of performing pterygium surgery in alternative settings, such as the laser suite, highlighting the benefits of cost-effectiveness, convenience and patient comfort. 

The present and future of EK

From CAIRS to CTAK, UT-DSAEK and More–Updates in Corneal Surgery Abound at ASCRS 2024
Dr. Winston D. Chamberlain talks iPSCs, ROCK inhibitors and more…

Dr. Winston D. Chamberlain of the OHSU Casey Eye Institute Clinic in Oregon (USA) began by contextualizing the evolution of keratoplasty, tracing back to the first human corneal transplant over a century ago.

He delved into comparative trials between Descemet’s stripping endothelial keratoplasty (DSEK), Descemet’s membrane endothelial keratoplasty (DMEK), and ultrathin Descemet’s stripping automated endothelial keratoplasty (UT-DSAEK), highlighting the ongoing debate regarding endothelial outcomes and the need for further research. 

“This question is important enough that the NIH has decided to sponsor a new DETECT trial. This is a multi-center trial looking at endothelial cell survival in DMEK versus UT-DSAEK in patients with complex eyes.” Dr. Chamberlain explained. 

He discussed the revolutionary potential of endothelial cell expansion and culture techniques, citing the groundbreaking study by Kinoshita and Koizumi demonstrating successful transplantation of cultured endothelial cells, as well as ongoing clinical trials in this domain.2 

Dr. Chamberlain shared promising technologies such as magnetic bead-coated core endothelial cells and collagen scaffold-based corneal endothelial grafts, offering alternative approaches to endothelial replacement.

Moreover, he explored the groundbreaking concept of deriving corneal endothelial cells from inducible pluripotent stem cells (iPSCs), highlighting the potential to eliminate the reliance on donor tissue altogether. 

“If we take those stem cells down the right stimulatory pathways, we can make cells that at least look like corneal endothelial cells,” he explained. 

Dr. Chamberlain also discussed the use of rho-associated protein kinase (ROCK) inhibitors in promoting endothelial cell migration and proliferation, and alternative technologies such as recombinant fibroblast growth factors and synthetic endothelial layers, offering potential solutions to address corneal diseases and shortages of donor tissues. 

“The distribution reflects that many countries don’t have access to the tissue that we have in the Western countries,” said Dr. Chamberlain, “I think it’s important to remember, as we think about these technologies, to make them accessible and affordable for everyone.”

Successful transitioning to DALK

From CAIRS to CTAK, UT-DSAEK and More–Updates in Corneal Surgery Abound at ASCRS 2024
Dr. W. Barry Lee describes the double bubble technique.

Dr. W. Barry Lee of the Georgia Eye Bank (USA) started off by emphasizing the importance of deep anterior lamellar keratoplasty (DALK) despite its relatively low frequency, suggesting that the numbers might be higher due to underreporting. 

Dr. Lee discussed various techniques for DALK, with a focus on Anwar’s big bubble technique, which he predominantly uses. He provided detailed instructions on depth control during trephination and emphasized the significance of achieving a big bubble.

Dr. Lee shared tips on air injection, advocating for the use of a cannula instead of a needle to reduce the risk of perforation. He also described a double bubble technique for confirming the presence of a big bubble and maximizing success rates.

Regarding donor tissue preparation, Dr. Lee suggested debulking the stroma if the big bubble is not achieved initially, providing practitioners with a second chance to create the desired bubble.

“Visual outcomes can be similar, but there’s faster rehabilitation, no open sky, no risk of endothelial rejection, less endothelial cell loss, longer graft survival, and increased tectonic support. However, DALK is technically challenging and surgeon skill-dependent,” said Dr. Lee, comparing DALK to penetrating keratoplasty (PK).

Tips for acute SJS management

Dr. Olivia L. Lee of the UCI Gavin Herbert Eye Institute in California (USA) addressed the critical aspects of diagnosing, managing and treating Stevens-Johnson Syndrome (SJS), a severe autoimmune condition. 

“This is a devastating disease, and if you’ve ever seen it, you’ll never forget it,” shares Dr. Lee. 

She emphasized the importance of immediate and frequent ocular assessments, as missing the opportunity to treat in the acute phase can lead to devastating consequences. “By the time we’re talking about symblepharon or ankyloblepharon, you’ve lost the battle,” warned Dr. Lee.

Although systemic management falls outside the purview of ophthalmologists, supportive burn care is typically administered alongside corticosteroids and intravenous immunoglobulin (IVIG). Topical treatments aim to preserve ocular surface health and vision, including lubrication, antibiotics and corticosteroids.

Regarding surgical interventions, Dr. Lee cautioned against outdated practices such as daily lysis of symblepharon using a glass rod. Instead, she advocated for early intervention using amniotic membrane transplantation (AMT) to preserve ocular surface integrity. 

Ultimately, Dr. Lee underscored the necessity of immediate intervention and close collaboration among healthcare providers to mitigate the potentially blinding effects of Stevens-Johnson Syndrome.

What’s next for KPro?

Dr. Marjan Farid, also of the UCI Gavin Herbert Eye Institute in California (USA), began by describing the ongoing challenges in treating corneal illnesses due to the worldwide shortage of corneal tissue. 

She emphasized the limitations of current keratoprosthesis (KPro) models, like Lucia Kpro, including integration issues, infection risks and long-term complications like corneal melts and glaucoma. 

Dr. Farid introduced several emerging technologies aimed at overcoming these challenges, including KeraKlear, GORE Synthetic Cornea, CorNeat dual membrane implant and EndoArt synthetic endothelial layer. 

Dr. Farid ended the session by acknowledging the need for further research and clinical trials to evaluate the long-term efficacy and safety of these emerging artificial corneas.

Editor’s Note: The 2024 Annual Meeting of the American Society of Cataract and Refractive Surgery (ASCRS 2024) is being held from 5 to 8 April in Boston, Massachusetts. Reporting for this story took place during the event.

References

  1. Rhee MK, Zakher M, Najac M, et al. Comparing Intracanalicular and Topical Steroid Use in Patients Undergoing Pterygium Surgery. Eye Contact Lens. 2024;50(4):183-188. 
  2. Kinoshita S, Koizumi N, Ueno M, et al. Injection of Cultured Cells with a ROCK Inhibitor for Bullous Keratopathy. N Engl J Med. 2018;378(11):995-1003. 
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