EyeWorld Asia-Pacific December 2018 Issue

70 EWAP NEWS & OPINION December 2018 with glaucoma had higher bacterial oral counts compared with controls (P<0.017) and that low-dose LPS administration in glaucoma animal models resulted in enhancement of axonal degeneration and neuronal loss. “Microglial activation in the optic nerve and retina as well as upregulation of TLR4 signaling and complement system were observed. Pharmacologic blockade of TLR4 partially ameliorated the enhanced damage,” the researchers wrote. The finding that commensal bacte- ria may have a role in glaucoma pa- thology could be relevant to other chronic neurodegenerative disor- ders, the researchers concluded. Uveitis and ocular inflammatory disease A review article concluded that in- testinal microbiota are potentially crucial in propagating inflamma- tory diseases of the eye and can be targeted for therapeutic benefit. 5 The author shares how several researchers have shown the impor- tance of the intestinal microbiome in the pathogenesis of uveitis and that in some studies, alteration of the microbiota with oral antibiot- ics led to decreased uveitis severity. Yet other researchers showed that a commensal bacterial antigen acti- vates retina-specific autoreactive T cells, which may indicate a com- mensal uveitis trigger. “Strategies that might be effective for target- ing the intestinal microbiota might involve several approaches, includ- ing the use of antibiotics, drugs that supplement beneficial bacte- rial components or target inflam- matory bacterial strains, dietary strategies, or microbial transplanta- tion,” Lin concluded. Contact lens wear and ocular microbiota To help determine if contact lens wear is associated with ocular mi- crobiota changes, Shin et al. com- pared the bacterial communities of the conjunctiva and skin under the eye from 58 subjects. 6 Dry conjunc- tival swabs from contact lens wear- ers had more variable and skin-like bacterial community structures, with a higher presence of Methylo- bacterium, Lactobacillus , Acinetobac- ter , and other bacteria. Although the results show that contact lens wear alters the microbial structure of the ocular conjunctiva, more research is needed to find out if the microbiome structure provides less protection from infection, the researchers concluded. Bringing it together It is too early to recommend specific treatments with the at- tempt to change the makeup of the ocular microbiome, said Ming Wang, MD, PhD , Wang Vision 3D Cataract & LASIK Center, Nash- ville, Tennessee. “This appears to be because as a field, we still do not understand the significance of the bacteria that reside on the eye and how we can alter this to promote good health,” he said. “Unfortunately, research on the ocular microbiota still lags behind other body sites such as the gut, skin, and oral cavity, and large-scale double-blinded stud- ies are ultimately needed to make solid recommendations on this subject,” said Rupa Shah, MD , ReVision LASIK & Cataract Surgery, Columbus, Ohio. That said, improved eyelid hygiene and cleaning along the eyelids can help to reduce bacterial proliferation in that area, and that could lead to a restoration of nor- mal healthy bacteria on the cornea and conjunctiva, Dr. Wang said. Ophthalmologists can con- tinue to advise patients to avoid extended contact lens wear and maintain good contact lens hy- giene, Dr. Shah said. “Furthermore, one should avoid harsh chemicals in the periocular region that could alter our natural microbiome and could contribute to pathologic states,” she said. It is too early to say if probi- otics—either geared toward the eye or taken orally—can improve ocular health, and Dr. Reid was not aware of any research until now that has led to inserting probiotic strains in the eye. “The opportunity to reduce inflammation, improve healing, and potentially deliver treatments for various conditions exists, but it will require low doses to be used, and only after safety is assured,” Dr. Reid said. “Probiotic strains don’t tend to colonize, so the intent would be to manipulate the function and output of the exist- ing microbiota or the metabolic activity that is causing disease.” However, a continued focus on the ocular surface microbiome will enhance understanding of the role of homeostasis microorganisms in ophthalmic disease and may inspire the development of new probiotic-based therapies to pre- vent and treat ocular disease, noted Lu and Liu in their report. 7 EWAP References 1. Chisari G, et al. Aging eye microbiota in dry eye syndrome in patients treated with Enterococcus faecium and Saccharomyces boulardii. Curr Clin Pharmacol. 2017;12:99– 105. 2. Watters GA, et al. Ocular surface microbiome in meibomian gland dysfunction. Clin Exp Ophthalmol. 2017;45:105–111. 3. Dennis-Wall JC, et al. Probiotics ( Lactobacillus gasseri KS-13, Bifidobacterium bifidum G9-1, and Bifidobacterium longum MM-2) improve rhinoconjunctivitis- specific quality of life in individuals with seasonal allergies: a double-blind, placebo- controlled, randomized trial. Am J Clin Nutr. 2017;105:758–767. 4. Astafurov K, et al. Oral microbiome link to neurodegeneration in glaucoma. PLOS One. 2014;9:e104416. 5. Lin P. The role of the intestinal microbiome in ocular inflammatory disease. Curr Opin Ophthalmol. 2018;29:261–266. 6. Shin H, et al. Changes in the eye microbiota associated with contact lens wearing. MBio. 2016;7:e00198. 7. Lu LJ, Liu J. Human microbiota and ophthalmic disease. Yale J Biol Med. 2016;89:325–330. Editors’ note: The physicians have no financial interests related to their comments. Contact information Park: lisa.park@columbia.edu Reid: gregor@uwo.ca Shah: rupas@revisioneyes.com Wang: drwang@wangvisioninstitute.com Eyeing the ocular – from page 69