EyeWorld Asia-Pacific September 2012 Issue

45 September 2012 EWAP GLAUCOMA The ‘latitude effect’ and pseudoexfoliation glaucoma by Faith A. Hayden EyeWorld Staff Writer Research shows gene-environment interaction link to development of disease Source: Maciej Frolow/Brand X Pictures/Getty Images AT A GLANCE • 99% of people with pseudoexfoliation glaucoma have the LOXL1 gene, but 80% of people without the disease have the gene as well • The development of pseudoexfoliation glaucoma can be due to environmental factors such as sun exposure and ambient temperature Hope for patients may lie in the link between genes, environment, and disease development F ew discoveries are as thrilling to physicians as the link between specific genes, and environmental interactions, and the development of disease. These findings have “real clinical implications,” said Louis R. Pasquale, MD , director, Glaucoma Service, Massachusetts Eye and Ear Infirmary, Boston, Mass., USA. “Even though you have a gene that predisposes you to a disease that you don’t want to get, if you do x, y, and z, you reduce your chances of getting that disease.” Such is the hope for pseudoexfoliation glaucoma, a blinding disease characterized by the accumulation of protein-like fibers within the anterior segment. Although the cause of this type of glaucoma is officially unknown, research over the last few years has illuminated some potential sources. A research group out of Norway discovered the LOXL1 gene variant was associated with exfoliation syndrome after scanning the genome of 1,000 patients with the disease and comparing it to about 14,000 controls. The results were astonishing. An unthinkable 99% of people with pseudoexfoliation glaucoma had the LOXL1 gene. “But the big kicker here is roughly 80% of controls also has this gene variant,” Dr. Pasquale explained. “This ratio of 99% to 80% held up in populations around the world when other people went to look for this gene and whether it was associated with exfoliation.” Interestingly, the prevalence of the disease varies widely around the world. For example, in China, prevalence of exfoliation syndrome is 0.5%, yet 80% of that population also has LOXL1. Views from Asia-Pacific Ashok GARG, MD Chairman and Medical Director Garg Eye Institute & Research Centre #235, Model Town, Dabra Chowk, Hisar-125005 India Tel. no. +09896025180 drashok_garg@yahoo.com T he coexistence of cataract and glaucoma is prevalent worldwide, especially in the age above 40. The surgical management of cataract with coexistent glaucoma has been an issue of debate for the last so many years, with experts having different views. In my view and experience, the surgical strategy decision must be customized to every patient depending upon the target pressure, the amount of glaucoma and the grade of visual disturbance caused by the cataract. The various surgical options, individual or combined, are as follows: • Only filtering surgeries are recommended in glaucoma with incipient cataract with good visual acuity. • Combined surgical procedures are recommended for progressive or advanced glaucoma refractory to maximal tolerated medical therapy with advanced cataract. • Two-site phacotrabeculectomy with mitomycin C augmentation achieves better results. • Phacotrabeculotomy plus deep sclerectomy offers significant IOP reduction and success. • Phaco deep sclerectomy (PDS) and phaco viscocanalostomy (PVCT) are highly effective in lowering IOP, especially with MMC augmentation. • Cataract extraction should be preferably avoided during the acute stage of primary angle closure glaucoma. Editors’ note: Prof. Garg has no financial interests related to his comments. continued on page 46