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OCT may be useful, objective tool for evaluating efficacy of dry eye therapy
Optical coherence tomography, when used to measure tear volume and ocular surface response after punctal occlusion, was shown to be potentially highly effective in evaluating dry eye treatment outcomes, according to a study recently published in Optometry and Vision Science.
Current tests for dry eye disease, such as Schirmer’s and staining with fluorescein and rose bengal dyes, have been criticized for their invasive nature and low repeatability, the study authors said.
OCT can provide a more objective means of evaluating tear retention in dry eye subjects than other measurement modalities, Murat Dogru, MD, PhD, one of the study investigators, said in an interview with Primary Care Optometry News.
According to the study authors, “Because the data are stored in the software of the OCT system, a clinician can always go back and compare it during the follow-up of any patient assessed by this system.”
Moreover, the OCT system will not capture images if the eye moves at all, they said. This allows for “a reliable and more precise evaluation of tear meniscus heights, whereas the tear meniscus height assessment by graticule scale is a subjective procedure and may change if the position of the patient changes,” the authors said.
Tear meniscus height measurements (TMH) by OCT significantly improved after punctal occlusion. Upper and lower TMH values were significantly lower in the dry eye patient group before punctal occlusion compared with after occlusion values (0.19 mm and 0.24 mm, and 0.28 mm and 0.35 mm, respectively; P < 0.001), the authors reported.
TMH values measured by OCT in dry eye control subjects did not change significantly.
The study included 30 eyes of 15 symptomatic dry eye patients not responding to nonpreserved artificial tears who received upper and lower punctal occlusion with silicone plugs. A control group was made consisting of 30 eyes of 15 age- and sex-matched dry eye patients. This group received only nonpreserved artificial tear treatment for 1 month.
All subjects underwent TMH with Visante OCT (Carl Zeiss Meditec, Dublin, Calif.), slitmicroscopy graticule scale TMH measurement, strip meniscometry testing, tear film break-up time measurement, ocular surface vital staining with fluorescein and rose bengal dyes and the Schirmer-1 test. Patients were examined before and after their month-long treatment.
“The need for a noninvasive, quick and comfortable dry eye diagnostic test led to the development of new methods such as real time corneal OCT, which revealed potential to analyze tear dynamics and assessment of tear meniscus after application of collagen punctal plugs,” the study authors said.
“The major benefits of OCT are that it is an easily repeatable, noninvasive imaging technique that correlates with other TMH testing modalities and provides images that are easily understandable to patients,” Dogru told PCON.
“OCT is expected to evaluate the effect of artificial tear drops very well, too,” he added. While no special module is needed for the OCT to conduct these measurements, “it needs expertise and is expensive,” he said.
Graticule scales in specific eye pieces of slit lamp microscopes might be less precise, but perhaps more realistic for clinicians, he added.
“OCT is not expected to be useful in tear meniscus volume determination in eyes with conjunctivochalasis, disorders of lid margin congruity or ocular surface-lid apposition,” Dogru said.
He clarified: “Most elderly patients have associated conjunctivochalasis, but lower grades are not evident unless you ask the patient to strongly and successively blink, which is not a major issue or an obstacle in Visante measurements. However, higher grades of conjunctivochalasis would not allow tear meniscus measurements.”
Dogru said additional applications for OCT could be found in the study of tear kinetics, “such as the assessment of tear drainage surgical procedures or confirmation of lacrimal drainage occlusion after punctum plug treatment, or the evaluation of treatment response in patients using tear secretagogues.
“Further studies on OCT TMH should determine age- and gender-specific cutoff values and the sensitivity and specificity of the test in the diagnosis of dry eye disease when performed alone or in conjunction with other dry eye tests,” he said. – by Daniel R. Morgan
For more information:
- Ibrahim OMA, Dogru M, Kojima T, et al. OCT assessment of tear meniscus after punctal occlusion in dry eye disease. Optom Vis Sci. 2012;89(5):E770-E776.
- Murat Dogru, MD, PhD, can be reached at the Department of Ophthalmology, Keio University School of Medicine, Shinanomachi 35, Shinjuku-ku, Tokyo 160-8582, Japan; muratodooru@yahoo.com.
Disclosure: Dogru has no relevant financial interests to disclose.