Research Digest

■ New Visual Field Test May Help Detect Glaucoma Earlier

A pilot study published in the October 2007 issue of the British Journal of Ophthalmology shows promise in early detection of glaucoma using the 3-D computer-automated threshold Amsler grid test (3D-CTAG), a variation on the Amsler 2-D grid developed in the 1940s to monitor the central visual field that uses varying levels of contrast and adds a third dimension. The 3D-CTAG is the creation of two of the study's co-authors (Drs. Fink and Sadun). Wolfgang Fink, Ph.D., a senior researcher at the California Institute of Technology and visiting associate professor of ophthalmology at the University of Southern California, spoke with Ophthalmology Management about the study.

Discussing the advantages of the 3D-CTAG over traditional visual field testing, Dr. Fink says, "Patients have a hard time undergoing the tedious and strenuous procedures of standard automated perimetry. With our technique, patients can test their visual field interactively at their own pace in usually under 5 minutes per eye."

The result is a more reliable test, not to mention results in three dimensions, the third being contrast sensitivity (Z-axis) in addition to the traditional horizontal and vertical visual fields (X- and Y-axes). In the study, Dr. Fink and his colleagues were able to detect visual field loss in 79% of the 66 eyes studied, with no visual field changes detected in the control group of 23 normal eyes.

Asked whether the 3D-CTAG could eventually emerge as a diagnostic tool in patients predisposed to develop glaucoma, Dr. Fink was circumspect. "Clearly more in-depth study is needed," he says. "However, we are in the process of publishing a study on patients with an established diagnosis of glaucoma."

Dr. Fink says one of the advantages of the technology is its portability. "You can use it in remote areas where you do not have access to hospitals, as in field work," he says. "You may have nothing around you, but you still have your laptop, and so it approaches the area of telemedicine."

The 3D-CTAG's applications may go far beyond telemedicine, however; Dr. Fink has also done work with NASA. "We developed the technology for ophthalmology," Dr. Fink says. "But in the case of, for example, flight to Mars, when astronauts are away for at least several months, this technology could assess the effects of radiation on the retina. We will be able to do regular testing at no additional payload during the mission." OM

■ The crystalens in Combination May Be the Best IOL Option in Some Patients

The crystalens accommodating IOL (eyeonics, Alisa Viejo, Calif.) compared favorably with the ReZoom (American Medical Optics, Santa Clara, Calif.) IOL and, when implanted in combination with the ReSTOR (Alcon, Fort Worth, Texas), outperformed the ReZoom in several areas, according to a paper published in the September 2007 issue of the American Journal of Ophthalmology.

Forty-nine patients were implanted after phacoemulsification with one of five combinations. The patients then underwent visual-performance tests, including measurements of uncorrected visual acuity (VA) and BCVA with a backlit ETDRS chart at three distances and contrast sensitivity at several cycles per degree, and filled out a quality-of-life (QoL) questionnaire.

Jay S. Pepose, M.D., Ph.D., chief author of the study and principal at the Pepose Vision Institute in the St. Louis metropolitan area, discussed his findings with Ophthalmology Management. Asked why the ReZoom lens was outperformed, Dr. Pepose responds, "This may be because ReZoom offers good distance vision and good intermediate vision, but not as good near vision as ReSTOR. Since the crystalens produces good distance and intermediate," he continues, "there is no particular synergy by adding ReZoom, which is a distancedominated zonal progressive."

Dr. Pepose and his co-authors concede in the article that a larger sample size — particularly of patients implanted with a combination of IOLs — needs to be studied to get more conclusive results; he says those studies are in the planning stages. Nevertheless, the authors' statistical analyses were able to demonstrate statistical significance with regard to crystalens' superiority over ReZoom in measurements of BCVA, uncorrected VA and QoL.

Stating his belief that the unique light-distribution of the crystalens is the key factor, Dr. Pepose says, "By definition, with multifocal lenses, the amount of light energy is distributed between multiple images or lost into higher diffraction orders," Dr. Pepose says. "With crystalens, 100% of light is distributed to near, intermediate or far vision at any given time." OM