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New imaging method appears to show early onset of retinal disease
Faint green autofluorescence from stressed cells may help to detect disease and its progression.
A new imaging technique may allow clinicians to detect retinal and optic nerve disease in the earliest stages, before obvious warning signs emerge and vision is impaired, according to the results of two studies.
The method may give ophthalmologists the ability to diagnose disease up to 10 years earlier than current clinical methods and assist in the management of ocular disease, Victor M. Elner, MD, PhD, told Ocular Surgery News in a telephone interview.
The technique identifies cells that are under metabolic stress but have not yet died.
“Normally, when ophthalmologists first note disease in the retina, a considerable number of cells have already died,” Dr. Elner said. “This technique allows early detection of disease by identifying cells under stress prior to cell death.”
Dr. Elner and Howard R. Petty, PhD, used the imaging technique to measure flavoprotein autofluorescence, a phenomenon in which cell proteins become fluorescent under metabolic stress. The fluorescence stems from molecular changes in the cell mitochondria, Dr. Elner said.
The authors studied flavoprotein autofluorescence occurring in women with pseudotumor cerebri, a condition that increases pressure on the optic nerve, potentially causing vision loss. On average, flavoprotein autofluorescence values were 60% higher in eyes with mild disease when compared with unaffected eyes.
In a second study, patients with diabetes exhibited increased flavoprotein autofluorescence when compared with age-matched controls, regardless of disease severity or duration. Moreover, patients with mild background diabetic retinopathy demonstrated significantly higher values when compared with those without retinopathy.
Drs. Elner and Petty and colleagues published their findings in Archives of Ophthalmology.
Detecting and tracking disease
The non-invasive imaging procedure, which takes less than 5 minutes, involves specialized cameras, filters and custom imaging software designed to detect low levels of cell fluorescence, Dr. Elner said.
Unstable cells emit green fluorescence in response to blue light shone into the eye.
“When the cell is under metabolic stress, the electronic configuration of the mitochondria changes so that these flavoproteins can absorb blue light, and they emit green light,” he said. “The green light is very faint and cannot be recorded using normal photographic techniques. The procedure does not result in an actual photograph but graphs that depict characteristics of the faint green autofluorescence that comes from the unstable cells.”
Diabetes or pre-diabetes is the most likely reason for elevated ocular autofluorescence because of its prevalence in the Unites States, Dr. Elner said.
“Since diabetes and pre-diabetes affect more than 70 million persons in the United States, an individual with abnormal autofluorescence would first be sent for glucose tolerance testing to see if they have overt diabetes or abnormal glucose tolerance,” he said.
Other potential conditions
In the event of a negative glucose tolerance test, the patient would be evaluated for glaucoma, age-related macular degeneration or other conditions that may cause cell or tissue stress within the eye, Dr. Elner said.
The technique also has potential for tracking disease progression.
“Metabolic autofluorescence is increased in those patients with disease complications,” he said. “We believe that this method has the potential to be used for monitoring disease and its treatment.”
Drs. Elner and Petty invented and built the imaging device at the University of Michigan, which holds applied and provisional patents. They have formed a company named OcuSciences and plan to market the device in 2010. They also plan to launch a multicenter clinical trial, Dr. Elner said.
For more information:
- Victor M. Elner, MD, PhD, can be reached at Kellogg Eye Center, University of Michigan, 1000 Wall St., Ann Arbor, MI 48105; 734-764-4182; fax: 734-936-3815; e-mail: velner@umich.edu. Dr. Elner is a co-inventor of the imaging device.
References:
- Elner VM, Park S, et al. Flavoprotein autofluorescence detection of early ocular dysfunction. Arch Ophthalmol. 2008;126:259-260.
- Field MG, Elner VM, et al. Rapid, noninvasive detection of diabetes-induced retinal metabolic stress. Arch Ophthalmol. 2008;126:934-938.
- Matt Hasson is an OSN Staff Writer who covers all aspects of ophthalmology. He focuses on regulatory, legislative and practice management topics.