Anterior chamber OCT imaging provides new insight into safe refractive surgery

Paris—A new anterior chamber optical coherence tomography (OCT) device (Visante, Carl Zeiss Meditec) is expected to play a major role in enabling safer refractive surgery, said Georges Baikoff, MD, at the European Society of Cataract and Refractive Surgeons meeting.

"We can expect that this new equipment will become a necessity for anterior chamber refractive surgery just as corneal topography is for corneal refractive surgery," said Dr. Baikoff, Clinic Monticelli, Marseilles, France. Dr. Baikoff had the opportunity to work with the first prototype of the device over a 2-year period. That experience showed it to be both user- and patient-friendly.

"The examination is a no-contact procedure, has the advantage of not requiring use of a water bath, and can be performed by a technician," Dr. Baikoff said.

Eyes implanted with phakic IOLs were the main focus of his investigations. Using the AC OCT prototype, Dr. Baikoff measured a variety of anterior chamber dimensions in relationship to angle-supported, iris-fixated, and posterior chamber IOLs.

Those studies yielded a number of interesting findings. Regarding angle-supported phakic IOLs, the research suggested a need to modify safety criteria to take into account the internal anterior chamber depth, which represents the distance to the corneal endothelium rather than to the epithelium.

In addition, measurements performed in a series of 100 eyes showed that the anterior chamber is an oval rather than a circle, and it has a statistically significant larger dimension along the vertical axis versus horizontally.

"That finding has important implications for proper sizing when seeking stability of anterior chamber phakic IOLs," Dr. Baikoff said. He also demonstrated forward movement of the anterior pole of the crystalline lens with accommodation and aging, and noted those phenomena should be taken into account when defining safe clearance between the crystalline lens and anterior chamber phakic IOLs.