EyeWorld Asia-Pacific June 2020 Issue

CORNEA 42 EWAP JUNE 2020 possible. It’s not the steroid,” Dr. Loden said. Crosslinking and intrastromal ring segments Intrastromal ring segments, often referred to by the brand name Intacs (Addition Technology), are designed to improve corneal contour, making the cornea less ÀÀi}Õ>À] y>ÌÌi} Ìi Vi] >` making it more symmetric, Dr. Hersh said. “That’s the general goal of using any corneal refractive surgery in keratoconus with or without crosslinking,” he added. Dr. Hersh said he is a proponent of combining the two procedures and referenced a study he coauthored in 2019 that included 200 patients, looking at how crosslinking and Intacs work together and whether the procedures should be performed separately or concurrently. 1 The study found that the combination of crosslinking and intrastromal ring segments leads to “substantial improvement in corneal topography” and sequential or concurrent procedures “show equivalent outcomes.” Dr. Rebenitsch said when he uses Intacs with crosslinking, he performs the procedure concurrently. He counsels patients that there is a chance they will have to be removed in the future but that there may be some residual effect if crosslinking is performed as well. Dr. Hersh said he would recommend Intacs if the patient has poor best-corrected visual acuity, has an inability to wear contact lenses 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 scarring 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 ÃÃÕi y>>Ì] viVÌ] 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- segmented Intacs may be more appropriate for keratoconus patients.” Crosslinking and topography-guided PRK All three ophthalmologists supported crosslinking 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 combined crosslinking and topography-guided PRK show that the effect is similar to Intacs. He acknowledged, however, that Intacs vs. topography-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 >vÌiÀÜ>À` vi `` > */ wÀÃÌ° “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. Six-month difference maps showing crosslinking alone versus concurrent topography-guided (TG) PRK and crosslinking. Both eyes improved 1 line in CDVA, while subjectively the patient noticed improvement only in his left eye, which received concurrent treatment. Source: Luke Rebenitsch, MD