Anterior segment OCT on par with standard lens opacity grading system

High-resolution imaging device provided safe, rapid and objective measurement of lens opacity.

Issue: June 2009

Anterior segment optical coherence tomography provided reliable assessment of lens density and opacity, according to results of a study.

Christopher K.S. Leung

Anterior segment OCT measurements correlated with Lens Opacities Classification System III (LOCS III) nuclear opalescence and nuclear color scores, the study authors said.

“The key advantage of using [anterior segment] OCT for lens assessment is objectivity,” corresponding author Christopher K.S. Leung, MD, said in an e-mail interview with Ocular Surgery News. “Having a wide measurement range and high measurement repeatability, anterior segment OCT could be used to sensitively detect cataract progression.”

Data on anterior segment OCT assessment of lens density and opacity are scant, the authors said. However, further research may lead to anterior segment OCT becoming the gold standard for evaluating cataract density in clinical practice and in epidemiological studies.

Patients and methods

The study included 55 eyes of 55 patients (30 women and 25 men) with a mean age of 69.9 years. One eye of each patient was randomly selected to undergo both LOCS III scoring and anterior segment OCT imaging.

For LOCS III grading, each pupil was dilated to a diameter more than 6 mm. One investigator, using a Haag-Streit slit lamp microscope, graded nuclear opalescence and nuclear color on a scale of 0.1 to 6.9, and cortical opacity and posterior capsular opacity on a scale of 0.1 to 5.9. Investigators used only nuclear opalescence and nuclear color scores to gauge correlations with anterior segment OCT images.

Investigators acquired anterior segment OCT images with the Visante OCT Model 1000 (Carl Zeiss Meditec). A lone investigator obtained three pairs of images for each patient.

The study had a few limitations. For example, the area chosen for lens density measurement included only the nucleus, the authors said.

“The current software of [anterior segment] OCT does not provide lens density measurement,” Dr. Leung said. “Because the infrared light cannot penetrate through the iris, lens signal posterior to the iris would be obscured and dilation is needed to maximize lens exposure.”

Measurement correlations

Study results showed a mean LOCS III nuclear opalescence score of 3.39 and a mean nuclear color score of 3.37. The authors saw significant correlations between anterior segment OCT measurements and LOCS III nuclear opalescence scores and nuclear color scores; both associations were statistically significant (P < .001). Data showed a slightly stronger association between the mean LOCS III nuclear opalescence score and anterior segment OCT nuclear density measurements.

“The slightly higher association with the [nuclear opalescence] score suggests that [anterior segment] OCT provides a better surrogate on lens density than lens color,” the authors said.

Also, data showed no significant association between logMAR visual acuity and mean LOCS III nuclear opalescence/nuclear color scores or mean anterior segment OCT lens density measurement.

“This result is not surprising, since lens density could be more related to high spatial frequency contrast and sensitivity,” the authors said. — by Matt Hasson

Reference:

Wong AL, Leung CK, Weinreb RN, et al. Quantitative assessment of lens opacities with anterior segment optical coherence tomography. Br J Ophthalmol. 2009;93(1):61-65.

Christopher K.S. Leung, MD, can be reached at Department of Ophthalmology & Visual Sciences, Chinese University of Hong Kong, Hong Kong Eye Hospital, 147K Argyle St., Kowloon, Hong Kong; e-mail: tlims00@hotmail.com. Dr. Leung has received speaker honorariums and research support from Carl Zeiss Meditec.