Progressive myopia rather than glaucoma may be primarily responsible for glaucomatous-appearing optic nerve damage in a subset of young to middle-aged individuals of Chinese descent. In a retrospective study of 16 Chinese men who were glaucoma suspects or patients, visual fields remained stable over a follow-up period of up to 7 years, leading researchers to postulate that this condition may not have the same natural history as primary open angle glaucoma in other populations. A correlation between myopia and glaucomatous optic nerve damage has long been known, and has recently been confirmed in several populations, including China.
Dr. Singh and his colleagues formally followed a group of 16 male patients of Chinese descent for up to 7 years and have since seen many other patients with this ethnic background, both male and female, in whom glaucoma was diagnosed but whose optic nerves and visual fields remained stable while under his care. Results of the series of 16 patients were published in the March issue of Ophthalmology (114:472-479).
"There is an epidemic of myopia in Chinese individuals all over the world. Myopia may lead to optic nerve changes that many may characterize as being glaucomatous," Dr. Singh noted. "But some of the patients that have myopia and glaucoma who are Chinese may have a natural history that is different from the progression of primary open-angle glaucoma [POAG] in other populations."
"The take-home point for clinicians is that if you see a young Chinese person who appears to have glaucoma and has apparent optic nerve damage and corresponding visual field loss, you might want to be certain it's a progressive condition before you consider filtration surgery, because surgery may lead to other problems that are worse than the condition itself," Dr. Singh said. "These are preliminary data, but based upon the resolution of the tools that we currently use to follow glaucoma, we think this condition may ultimately slow or stabilize. If the condition is not progressing toward vision loss that the patient will notice someday, then it's probably best not to perform surgery."
When those patients with suspected glaucoma come to Dr. Singh's practice and already are undergoing treatment, he generally does not stop therapy but also does not escalate it unless the patient's condition clearly is worsening. If a patient is not undergoing treatment on referral, then he generally suggests either no treatment or minimal treatment with IOP-lowering drops initially, reserving more aggressive therapy for patients who show definitive progression of disease.
"I think it's reasonable to treat, but treat gently, until we know more about the condition," Dr. Singh explained. He added that, in these instances, it is better to focus on whether the patient's condition is getting worse rather than on a target IOP goal.
Ophthalmologists generally are tempted to set a very low target IOP goal when they see a young patient with what appears to be glaucomatous visual field loss, he said. Without knowing the history of how the patient developed the field loss, it may do more harm than good to set a low target IOP goal and do anything, including surgery, to reach it, Dr. Singh said.