REFRACTIVE 16 EWAP JUNE 2022 So-Hyang Chung, MD Professor, The Catholic University of Korea Banpo-Ro 555, Seoul, South Korea chungsh@catholic.ac.kr ASIA-PACIFIC PERSPECTIVES Nowadays, when the importance of genetics is emphasized in the medical field, it is encouraging that various studies using genetics are being conducted in ophthalmology. I am very interested in the presented issue and eÝpect that it will be of great help in the early diagnosis and treatment of keratoconus. To the siblings and offspring of keratoconus patients, genetic tests could provide valuable information. During refractive surgery screening, these tests would be especially beneficial for the patient with abnormal clinical eÝaminations and risk factors and help surgeons make decisions for phakic IO s and refractive surgery with crosslinking. -ince the cost of testing is not small, more specific guidelines for when to perform genetic testing (e.g. corneal thickness, astigmatism, topographic characteristic) might be needed. There is no objection to conducting the test in patients with a family history or abnormal clinical eÝamination, but I don½t think these biomechanical tests would be necessary for normal patients. ditors½ note\ *rov° hÕng deVlared no releÛant finanVial interests° risk for keratoconus based on a patient’s corneal genetics provides invaluable information, Dr. 9eu said. ºI think corneal genetic screening is essential for any refractive screening patients who present with other risk factors on the initial visit, i.e., thinner corneas, young patients with against-the-rule astigmatism, higher astigmatism, more centrally steep astigmatism. Also, I always screen patients who I½m seeing for an enhancement evaluation for the first time, or in situations where I µuestion the topographic pattern for inferior steepening. Furthermore, I reµuest corneal genetic screening at the initial visit for keratoconus suspect evaluations, and I always recommend it to my known keratoconus patients for their siblings or offspring.” Dr. Yeu said she offers this test to patients in cases where she thinks the information would be truly additive to the clinical decision-making process. Currently, the test is paid for out of pocket. Dr. Yeu estimated that patients are charged $350–500. It½s important to still use other screening tools to make the keratoconus diagnosis. Dr. Yeu uses pachymetry, topography, and tomography. Corneal epithelial mapping with O T and biomechanical testing can further enhance the ectasia screening process. She also noted the importance of looking at family history, eye rubbing, systemic comorbidities, ethnicity, and other risk factors. Dr. Yeu said eye rubbing can be a big cause for concern. She strongly urges her patients with known keratoconus or suspicious corneal astigmatism to avoid this. Contact lens intolerance can also point to worsening progression of corneal astigmatism. ºI watch the corneal astigmatism closely in these patients, as contact lens intolerance can be from dry eye disease or contact lens conjunctivitis,” she said. Availability of tests The first commercially available test for corneal dystrophies was made in Korea by Avellino Precision Medicine in 2008, Dr. Yeu said. This only tested for one T I mutation known to cause Avellino corneal dystrophy (now also known as GCD2). The launch of that test led to more testing in South Korea and Japan, and eventually, more mutations were defined. The Avellino test was modified by Avellino Precision Medicine to include five mutations of the T I gene. “Today, 42 labs offer corneal disease genetic testing, according to a search on the Genetic Testing Registry,” Dr. Yeu said. “Universities with their own labs are also able to offer this type of testing.” In 201, Avellino launched the AvaGen test, which Dr. 9eu said uses neÝt-generation sequencing to look for more than 70 mutations of the T I gene for corneal dystrophies, as well as markers across 75 other genes associated with keratoconus and related diseases. The developments in testing and therapy resulted in FDA approval of voretigene neparvovec-râyl ( uÝturna, Spark Therapeutics) in 2017, the first gene therapy of its type approved for confirmed biallelic RPE65 mutation-associated retinal dystrophy. “While the prevalence of this genetic disease is considerably less than other eye diseases, the promise that this process of testing and continued on page 18
RkJQdWJsaXNoZXIy Njk2NTg0