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Screening devices may not adequately detect narrow angle
Ophthalmology. 2008;115(10):1720-1727.
Screening devices may be inadequately sensitive to detect narrow angle in phakic eyes — an important predictor of early glaucomatous changes in the eye.
A cross-sectional, observational, community-based study of 2,052 eyes in Singapore showed low sensitivity in detecting narrow angle by use of a scanning peripheral anterior chamber depth analyzer (Takagi), IOLMaster (Carl Zeiss Meditec) or Visante anterior segment optical coherence tomography (Carl Zeiss Meditec). Gonioscopy was used as a control in the study.
The devices were used in community-based screening, which is important in this population, the study authors said, because of the high prevalence of primary angle closure glaucoma. Some studies have suggested that narrowing of the space between the iris and the trabecular meshwork may be an important risk factor for this disease.
“All three instruments assessed in this community-based screening study were safely operated by technicians, provided immediate results and performed reasonably well,” the study said, “but none gave very high combinations (> 95%) of sensitivity and specificity when trying to identify subjects with [narrow angles].”
This study highlights the need to perform gonioscopy, which is underutilized in clinical practice. Both the American Academy of Ophthalmology and the American Glaucoma Society have undertaken efforts to increase awareness of gonioscopy in clinical practice. While I do not believe many clinicians rely on technology to assess the anterior chamber angle, this research certainly suggests that we should not abandon gonioscopy quite yet in favor of newer technologies. There is still probably much that can be learned from these new technologies that will aid in clinical care, but it would be of benefit to have a truly objective tool for assessing the anterior chamber angle. Hopefully, further research or development of new technologies will help to reach this goal.
– Louis B. Cantor, MD
OSN Glaucoma Section Member