Value of optical coherence tomography for anterior segment surgery

Anterior segment optical coherence tomography (AS-OCT) is an important new noncontact imaging technology that uses a 1310 nm super luminescent diode. It can be used to assess anterior chamber biometry, corneal thickness, lens thickness, and angle configuration; to visualize pathological processes; to evaluate postsurgical anatomy and posttraumatic eyes; and to image phakic intraocular lenses and intracorneal ring segments. Because it is a noncontact technique, it can also be used intraoperatively, which could be useful during trabeculectomy and after deep anterior lamellar keratoplasty to detect abnormalities in the cornea and interface. A disadvantage of AS-OCT is its inability to penetrate the iris pigment epithelium, which makes it impossible to evaluate the structures behind the iris. The most frequently used devices are time-domain AS-OCT, but new Fourier-domain OCT devices, which have faster image acquisition and higher resolution, are currently under investigation.