Eyeworld

I APRIL 2020 | EYEWORLD | 73 effectively, or if there is a major difference between the two eyes. "If they are doing well with their glasses or contacts, don't rock the boat," he said, adding that Intacs can't be used if the cornea is too thin in the paracentral area or if there is scar- ring where the segment would go. Dr. Loden doesn't use Intacs, citing that he has had to remove multiple Intacs. "The cornea does not like foreign bodies in it; it tries to extrude them," Dr. Loden said. "You can get thinning over the Intacs, you can get them eroding through the cornea. After a period of time, they want to extrude themselves from the eye." Dr. Hersh said he did a study of his Intacs population, following 600 patients for 10 years, and found the removal rate was 6–7%. 2 One- third of these were for a medical issue (inflam- mation, infection, extrusion, etc.), and two- thirds were for optical or topography reasons, such as changing the segment size or position. "In general, they seem to be quite safe," Dr. Hersh said. "We've found the use of single-seg- mented Intacs may be more appropriate for keratoconus patients." Crosslinking and topography-guided PRK All three ophthalmologists supported crosslink- ing combined with topography-guided PRK, provided the patient was a candidate (has a thick enough cornea). "The only thing we've noticed with doing combination PRK and crosslinking is you'll typically get more aggressive haze, and there are reports that you can get slower healing time and re-epithelialization of the cornea," Dr. Loden said. Dr. Hersh said his early results with com- bined crosslinking and topography-guided PRK show that the effect is similar to Intacs. He acknowledged, however, that Intacs vs. topogra- phy-guided PRK might be more appropriate for different kinds of patients. Dr. Rebenitsch said he'll usually perform topography-guided PRK concurrently with crosslinking or occasionally afterward if he did a PTK first. "I wait a minimum of 6 months before doing any additional treatment," he said. "There are differing views out there, but I personally would rather do a laser before crosslinking than after to avoid removing too much of the tissue that has now been crosslinked. That being said, there are reports of significant haze after crosslinking when laser was done concurrently, so there are many docs who recommend laser afterward only. With EBK and avoiding the removal of more than 50 µm of tissue with the laser, that has not been my experience though." An emerging refractive therapy Dr. Hersh described another technique that he's working on to benefit keratoconus patients refractively. It's called corneal tissue addition for keratoconus, or CTAK. He said it uses pre- served corneal tissue that is cut into customized shapes with a femtosecond laser. "Depending on the location of the cone and thickness of the cornea, we are implanting preserved corneal tissue to preserve corneal topography and thicken the cornea," he said. About 10 patients have been treated with this technique so far and "it's looking very promising," Dr. Hersh said. "The benefit of that is you can make different sizes and shapes, customized for the patient," he said. References 1. Hersh PS, et al. Corneal crosslinking and intracorneal ring segments for keratoconus: A ran- domized study of concurrent ver- sus sequential surgery. J Cataract Refract Surg. 2019;45:830–839. 2. Nguyen N, et al. Incidence and associations of intracorneal ring segment explantation. J Cataract Refract Surg. 2019;45:153–158. Relevant disclosures Hersh: Avedro (acquired by Glaukos), Lions Vision Gift, Addition Technology Loden: None Rebenitsch: None Contact Hersch: phersh@vision-institute.com Loden: lodenmd@lodenvision.com Rebenitsch: dr.luke@clearsight.com "There are differing views out there, but I personally would rather do a laser before crosslinking than after to avoid removing too much of the tissue that has now been crosslinked." —Luke Rebenitsch, MD

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