Can anterior segment imaging replace gonioscopy?

The Academy’s latest Ophthalmic Technology Assessment reviews the literature to determine whether anterior-segment imaging helps diagnose primary angle-closure glaucoma. While useful, they conclude that none of the imaging devices studied can serve as a substitute for gonioscopy.

All modalities studied – ultrasound biomicroscopy (UBM), anterior-segment coherence optical tomography (OCT), Scheimpflug photography and the scanning peripheral anterior chamber depth analyzer (SPAC) – demonstrated a strong association with results obtained from gonioscopy. However, none provided sufficient information about the anatomic features of the anterior-chamber angle to be considered a substitute for gonioscopy.

Still, each of these imaging methods provide an objective assessment and documentation of the angle, as well as quantitative information describing the anterior-segment anatomic features that can be useful for evaluating PACG.One possible advantage of anterior-segment imaging overall is the ability to determine which eyes may benefit from laser peripheral iridectomy.

Additionally, they evaluated the advantages and disadvantages of each device in relation to gonioscopy. UBM imaging provides the greatest range of anatomic information given its ability to image structures posterior to the iris. Scheimpflug photography and SPAC provide more limited information because of their use of light in the visible spectrum that does not allow direct imaging of the anterior-chamber angle. The noncontact nature of OCT, Scheimpflug photography and SPAC allow greater ease of obtaining images than does UBM, making them more practical for use in large-scale screening programs for PACG.

The authors conclude that because our understanding of the specific anatomic parameters that may be most useful in the diagnosis of PAC and the prospective validation of such parameters remains incomplete, the added benefit of using these devices for clinical care is unclear.