Eyeworld

EW CORNEA 96 April 2016 diabetes and keratoconus, and the researchers of those papers are di- vided—3 papers suggest a protective effect of diabetes against keratoco- nus, and the other disagrees. "In the cornea, researchers have hypothesized that diabetes causes crosslinking of corneal fibers to form free radicals. The crosslinking tightens the fibers and strengthens them, so we hypothesize that people with diabetes would be less likely to develop keratoconus." "We looked at diabetes in 2 ways. We looked at keratoconus pa- tients diagnosed with diabetes and different severities of keratoconus and people with diabetes," she said. "Regardless, all types of keratoconus patients were less likely to have dia- betes compared to controls." EW References 1. Gomes JA, et al. Global consensus on keratoconus and ectatic diseases. Cornea. 2015;34:359–69. 2. Woodward MA, et al. The association between sociodemographic factors, common systemic diseases, and keratoconus: An analysis of a nationwide health care claims database. Ophthalmology. 2015 Dec 16. [Epub ahead of print] Editors' note: Dr. Woodward has no financial interests related to her comments. Contact information Woodward: mariawoo@med.umich.edu by Michelle Dalton EyeWorld Contributing Writer collagen vascular disease had a 35% lower odds of keratoconus, and no association was found between kera- toconus and allergic rhinitis, mitral valve disorder, aortic aneurysm, or depression, Dr. Woodward said. She recommends screening pa- tients with Down syndrome for kera- toconus because the risk is so much greater in that subset of patients (six times higher), and "that population sometimes struggles with communi- cating visual difficulties to eye care professionals." Dr. Woodward added that, as with any claims data analysis, a lim- itation is that causal relationships cannot be drawn; it can only show associations between 2 variables. "We would love to have infor- mation about the history of eye rubbing and the patient's family history of keratoconus because those are known to be big predictors of having keratoconus," she said. "But unfortunately historical information is not present in health care claims databases." Diabetes link In their multivariable regression model, people with uncomplicated diabetes had a 20% reduced odds of keratoconus and those with diabetes complicated by end-organ damage had a 52% reduced odds of kerato- conus. Dr. Woodward's group is 1 of 4 to report on the association between keratoconus than females and that did bear out in our statistics," she said. "We also wanted to learn what systemic medical conditions were linked to keratoconus because the literature is not clear." While race has been examined before in terms of risk of keratoco- nus, this study's finding that African Americans and Latinos have a 50% higher rate of keratoconus as com- pared to Caucasians "was previously unknown. The finding that there is a 39% lower rate among people of Asian descent also contradicts previous research," Dr. Woodward said. "Our findings differ from those of the Delphi panel, but that was an international group that included respondents from Singapore and Japan. We can state our findings showed Asians participating in a U.S. insurance health care plan had re- duced odds of keratoconus without disagreeing with the Delphi panel findings." More work is needed to reconcile those differences, she said. Keratoconus risk factors "Eye health relates to total body health, and we need to be aware of more than just the ocular condi- tions when we care for patients," Dr. Woodward said. In this analysis, patients with sleep apnea and asthma both showed increased risk of kerato- conus, while those with diabetes showed a reduced risk. People with A health care claims data analysis finds several systemic diseases raise the odds of keratoconus, and persons of certain races or ethnicities are at higher risk L ast year, the Global Delphi Panel of Keratoconus and Ectatic Diseases reported on risk factors for develop- ing keratoconus, including ocular allergy, atopy, connective tissue disorder, and Down syn- drome, but also that people of Asian and Arabian ethnicity might have a greater risk profile. 1 However, a new, retrospective health care claims data analysis suggests that African Americans and Latinos also present a higher risk compared with Cauca- sians, 2 said Maria Woodward, MD, Department of Ophthalmology and Visual Sciences, University of Michi- gan Medical School, Ann Arbor, and the Institute for Healthcare Policy & Innovation, University of Michigan. Dr. Woodward said the claims data analysis represented the largest-ev- er study of keratoconus, including more than 16,000 people with keratoconus matched 1:1 to people without keratoconus. "There had been suggestions that males were more likely to have Risk factors for keratoconus sealed reservoir over the cornea and a vacuum pump that induces nega- tive pressure," Dr. Myung said. Using the system, therapeutic levels of riboflavin were delivered to the corneas of enucleated porcine eyes and rabbit eyes in vivo. "Riboflavin 0.1% without dex- tran was used for all experiments; fluorescein staining and clinical evaluation of the samples were per- formed to evaluate for any epithelial defects caused by the procedure; samples of excised corneal buttons 8.25 mm in diameter were evaluated by mass spectrometry to determine the total riboflavin content as a function of time and vacuum pres- sure," Dr. Myung said. According to Dr. Manche, neg- ative pressure accelerates diffusion, and no significant change/adverse effect in IOP was observed even with increased vacuum. "The device's plate curvature matches that of the cornea, and only gentle contact is required to initiate vacuum; IOP is only elevated if direct axial pressure is applied, which in this case, is not necessary," Dr. Manche explained. "We have developed a novel, vacuum-based transepithelial deliv- ery system for delivering therapeutic doses of riboflavin to the cornea. In pre-clinical studies, the system delivered significantly higher levels of stromal riboflavin compared to epithelium-on topical administra- tion," Dr. Myung said. "The technology has the poten- tial to deliver other drugs noninva- sively into the eye as well, and [in our future work] UV irradiation will be used to crosslink corneas imbibed with riboflavin with this delivery system," Dr. Manche concluded. EW References 1. Taneri S, et al. Evaluation of epithelial integrity with various transepithelial corneal cross-linking protocols for treatment of kera- toconus. J Ophthalmol. 2014;2014:614380. 2. Vinciguerra P, et al. Imaging mass spec- trometry by matrix-assisted laser desorption/ Vacuum-based continued from page 94 ionization and stress-strain measurements in iontophoresis transepithelial corneal collagen cross-linking. Biomed Res Int. 2014; 2014:404587. Editors' note: Drs. Manche and Myung have financial interests with Seros Medical (Palo Alto, California). Drs. Taneri and Vinciguerra have no finan- cial interests related to their comments. Contact information Manche: edward.manche@stanford.edu Myung: davemyung@gmail.com Taneri: taneri@refraktives-zentrum.de Vinciguerra: info@vincieye.it

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