Researchers at Seoul National University Bundang Hospital (SNUBH) have proved for the first time that a non-invasive eye test is as accurate as an invasive one in observing blood flow in the eye of glaucoma patients, the hospital said.

Glaucoma is characterized by eye nerve damage that could lead to vision loss and even irreversible blindness. The disease impacts around five percent of people 60 years old and older.

Decreased blood flow around the optic nerve, thought to be one of the causes of glaucoma, has been conventionally observed through an invasive ophthalmic angiography using a cyanine dye called indocyanine green (ICG), the hospital said.

The ICG angiography, which injects the dye intravenously, has caused complications in glaucoma patients because of side effects such as contrast sensitivity and allergic reactions – creating difficulties in both treatment and research.

For the first time, a research team led by SNUBH Professors Kim Tae-woo and Lee Eun-ji proved the efficacy of a non-invasive method using optical coherence tomography (OCT) in observing decreased blood flow in the eye.

The team studied 30 glaucoma patients to determine whether OCT – the non-invasive imaging test that uses light waves to take cross-section pictures of one’s retina – was just as accurate as the invasive method.

Optical coherence tomography (left) and indocyanine green angiography of glaucoma patients. The non-perfusion area (area with reduced blood flow) surrounded by a red dotted line is consistent.

Researchers compared and analyzed the images from each type of test to find no difference in the localized decrease in choroidal blood flow between the two, indicating that the non-invasive method is as accurate as the conventional invasive one. The study is the first to prove OCT suitable for observing blood flow around the optic nerve in patients with glaucoma, SNUBH said.

"It is meaningful that we have proved for the first time in the world that an optical coherence tomography is an accurate test that can replace an existing invasive test. The non-invasive method allows people to get a safer examination and avoid side effects such as contrast sensitivity and allergies, among others,” Professor Lee said.

Co-researcher Kim also said, “Future research should reveal the specific mechanisms by which optic nerve blood flow deteriorates optic nerve damage in patients with glaucoma.”

The results of the study were published in a recent issue of the international journal, Ophthalmology.

yjc@docdocdoc.co.kr

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