Reshaping the Future of Keratoconus Care: Dr. Rahul Tonk on CTAK at AAO 2025

November 19, 2025

Watch the full presentation on our Education Page.

At the American Academy of Ophthalmology (AAO 2025) meeting, corneal surgeon Dr. Rahul Tonk presented his clinical insights into CTAK (Corneal Tissue Addition for Keratoconus), a customized, tissue-based innovation from CorneaGen designed to improve visual function and corneal shape. CTAK is emerging as one of the most promising innovations for patients with keratoconus.

“Importantly, it’s customized tissue. So we’re able to customize thickness, arc length, optical zone, and so on and so forth. We’re able to apply customization by using pre-operative tomography… It gets run through CorneaGen’s nomogram…and then cut to specification,” said Dr. Tonk.

 

What Is CTAK? A Customized, Biologic Approach to Keratoconus Treatment

 

CTAK is an advanced procedure that uses gamma-irradiated, sterile, non-immunogenic corneal tissue inlays. These inlays are custom-cut based on the patient’s corneal tomography, with each graft tailored to the severity and location of the cone.

This biologic, tissue-addition technique allows surgeons to target irregular astigmatism at its source, helping normalize the corneal surface and enhance vision.

Key Advantages of CTAK for Keratoconus Patients

• Patient-ready, gamma-irradiated donor tissue that reduces immunologic risk and maintains natural corneal lamellae
• Customized laser-cut design guided by precise tomography data
• Biologic tissue-based contouring, offering a natural alternative to synthetic implants
• Minimally invasive and reversible

Unlike intracorneal ring segments or full-thickness grafts that remove or replace tissue, CTAK reshapes the cornea by adding biologic tissue, offering a more physiologic and adaptable solution.

 

CTAK Workflow: Streamlined Planning and Efficient Surgical Procedure

 

CTAK integrates smoothly into modern refractive and corneal practices. Surgeons upload tomography data through a secure platform, and CorneaGen uses a proprietary nomogram to design the custom allograft. The tissue inlay arrives ready for implantation and can be stored until the procedure (CTAK has a 2-year shelf life).

During the CTAK Procedure

1. A femtosecond laser creates a precise corneal channel.
2. The custom-cut tissue inlay is manually inserted into the channel.
3. The tissue inlay is positioned at a superficial depth of ~200 microns, allowing significant anterior shape change while preserving structural integrity.

“It’s all a very streamlined process, very user friendly,” Dr. Tonk explained.

 

CTAK Clinical Outcomes: Improved Vision and Corneal Stability

 

Dr. Tonk’s clinical experience with CTAK for keratoconus shows encouraging improvements in:

• Uncorrected and corrected visual acuity (UCVA and BCVA)
• Corneal smoothness and regularity
• Improved tolerance for glasses or lenses
• Enhanced quality of vision

Dr. Tonk noticed that many of his patients experience reduced dependence on specialty contact lenses, while those who continue wearing them often enjoy a better fit and increased comfort.

“If we can raise [the patient’s] uncorrected and their best spectacle-corrected acuity, we’re raising the floor… and their RGP fits are going to be so much better after you flatten the cornea,” said Dr. Tonk.

 

Why CTAK Matters: A New Option for the Keratoconus Treatment

 

CTAK represents a significant advancement in corneal therapeutics, offering a personalized, minimally invasive solution for keratoconus and other ectatic disorders. Its ability to reshape the cornea using biologic tissue makes it an appealing option for patients who may not be ready, or able, to undergo more invasive procedures like a transplant.

 

About CTAK

 

CTAK is CorneaGen’s proprietary corneal contouring procedure engineered to:

• Improve corneal regularity
• Enhance corneal thickness in ectatic areas
• Boost visual performance

CTAK uses sterile, gamma-irradiated, laser-cut donor tissue inlays uniquely designed for each patient’s corneal topography.

The procedure is currently available only to trained surgeons in select regions. Patient selection and outcomes may vary depending on disease severity and surgical technique.

 

 

CTAK Expands Surgeon Access: Procedure Now Compatible with Ziemer GALILEI platform  

July 24, 2025

CTAK Expands Surgeon Access: Procedure Now Compatible with Ziemer GALILEI platform 

Corneal Tissue Addition for Keratoplasty (CTAK), the groundbreaking solution for contouring keratoconic eyes, has taken a major step forward in accessibility with the recent integration with Ziemer GALILEI technology. Until now, CTAK’s compatibility was limited to ophthalmology clinics using the OCULUS Pentacam® to assess the surface of a patient’s eye – specifically the severity and location of the cone shape, the hallmark sign of keratoconus.

“The integration of CTAK with the Ziemer GALILEI diagnostic platform marks a significant step forward in the precision and personalization of keratoconus treatment,” said Dr. Peter S. Hersh, MD, originator of CTAK.  “By combining high-resolution corneal tomography with laser-guided stromal inlay preparation, we can deliver an anatomically optimized and patient-specific approach to corneal reshaping. Such technological innovation moves us to safer, more predictable, and meaningful improvements in visual function for patients with keratoconus.”

After nearly a decade of development, CTAK was commercially launched by CorneaGen in 2024 and continues to gain momentum in the industry, helping surgeons transcend the traditional standards of care in treating keratoconus. CorneaGen is the exclusive provider of the custom, patient-ready tissue inlays for the CTAK procedure.

“At CorneaGen, our mission goes beyond innovating affordable technologies and treatments – it’s about expanding access to innovations for patients around the world,” said Bernie Iliakis, CEO of CorneaGen. “Our partnership with Ziemer and the integration of their advanced GALILEI imaging systems mark a pivotal step in this journey.”

The GALILEI CTAK Software is now available and requires a system update to surgeon’s existing GALILEI platform. David Bragg, President of Ziemer USA, said, “We are thrilled to complete our product offering for CTAK patients. With the addition of the Galilei CTAK software, in combination with our FEMTO Z8 LDV femtosecond laser platform, we can now provide surgeons and patients with a fully integrated surgical solution aimed at restoring vision and improving outcomes.”

In the coming months, CorneaGen will partner with a cohort of surgeons using the Ziemer GALILEI diagnostic platform to integrate the procedure into their practice, making high-quality, personalized keratoconus treatment more widely available.

In addition, CorneaGen will continue to make progress on the expansion of CTAK’s global footprint. With nearly 20% of ASCRS wet lab participants practicing outside the U.S., there is significant opportunity for continued global growth.

By making CTAK platform-agnostic and expanding globally, CorneaGen expects increased adoption of CTAK across academic centers, ambulatory surgery centers, and private practices worldwide. As more surgeons gain access to its capabilities, the future of keratoconus treatment looks increasingly precise, personalized, and patient-centered.

 

 

Bernie’s Quarterly Update – July 2024

July 30, 2024

A message from Bernie Iliakis, President & CEO of CorneaGen

 

As we close the second quarter of 2024, we’re incredibly proud at CorneaGen to have launched commercial availability of Corneal Tissue Addition for Keratoplasty (CTAK). An innovative solution to corneal contouring, CTAK is a true treatment advancement for keratoconic eyes—providing patient ready, gamma-irradiated sterile, non-immunogenic corneal tissue segments. We couldn’t be more excited about this new opportunity to change the lives of those affected by keratoconus, while also honoring and making the most of each corneal donation.

And we don’t do any of this alone—with ongoing innovations brought to the market by strong partnerships, I’m pleased to share more about what CorneaGen has achieved in the last few months.

 

Innovations in corneal care

CTAK co-inventors include Drs. Peter Hersh, Steven Greenstein, and John Gelles. More than 150 successful surgeries have been completed to date, and we have 30 active surgeons using the solution. Just one recent testimonial includes:

“Following a CTAK procedure, patients can experience a ‘wow’ effect with their vision. We have seen immediate impressive improvements in best corrected and uncorrected vision. This immediate improvement at the first follow-up is an exciting experience for those dealing with Keratoconus.” – Dr. William Wiley, Medical Director, Cleveland Eye Clinic Division of Midwest Vision Partners

There’s been a lot of focus around corneal allogenic intrastromal ring segments (CAIRS) in the last few years and even growing international interest in a solution such as CTAK. We want to encourage everyone interested to reach out, as we continue delivering CTAK to the market, and don’t miss the webinar we’re hosting on August 6^th at 6pm Pacific, highlighting the solution.

 

Partnerships and philanthropy

Organizational partnerships that led to the creation of CTAK include CTAK LLC and Ziemer, and we have many others. CorneaGen has a long history with Geuder AG, as the distributor of their glass cannula used for DMEK surgery. We’re continuing to grow in the glaucoma space with collaborations like Iantrek Inc., whereby we assemble, package, and distribute the newly launched CycloPen, which utilizes scleral tissue for microinvasive glaucoma surgery (MIGS). CorneaGen’s collaborations to advance treatments, as well as efforts to provide sterile grafts for glaucoma and cornea surgeries through our Long-Term Tissue program, continue to be world class in the industry.

 

And I wanted to highlight CorneaGen’s Jared Young, our VP of Sales and Marketing, on his co-founding of the Trillium Vision Foundation. As this organization helps restore vision globally through a community of people and partners, CorneaGen is proud to support their philanthropic work. Watch the link below for coverage of their most recent trip to San Salvador.

https://eyewire.news/tv/trillium-vision-foundation.

 

Growth and expansion

In closing, I also wanted to make note of CorneaGen’s growing presence in California and Florida. Announced earlier this year, CorneaGen expanded eye recovery and processing services of donor tissue for facilities throughout California. We are in the midst of facility expansion in the Bay Area and Orlando, growing our team in both locations. We close a strong and eventful first half of 2024 with significant impact in the ophthalmic space.

 

Thank you as always to our surgeons and partners for helping support CorneaGen’s mission. I look forward to connecting on our progress next quarter.