The AC OCT is a user-friendly instrument for evaluating the anterior segment and examining the AC (cornea, iris, crystalline lens, and iridocorneal angle). The 1,310 nm light wavelength is blocked by pigments, preventing examination behind the iris. However, the AC OCT is capable of good image quality and visualization of the anatomical relationships in the anterior segment, even behind an opaque cornea.

Perfect tolerance is expected when one implants a phakic intraocular lens (pIOL) in the anterior segment. Not only should the material be compatible, but the pIOL must respect the anatomy of the anterior chamber. Based on 3 years of experience using an anterior segment optical coherence tomographer (Visante OCT, Carl Zeiss Meditec), I have defined numerous safety criteria for pIOLs. The internal dimensions of the anterior chamber must be considered along different meridians. I propose an objective measurement of the iris dome, the crystalline lens rise (CLR), which is the distance between the anterior pole of the crystalline lens and a line joining the 2 opposite iridocorneal angles. In a series with the Artisan IOL (Ophtec), pigment dispersion syndrome appeared in 70% of cases in which the CLR was greater than 600 microm. Angle-supported IOLs must be placed relative to the anterior chamber's largest diameter; in the same series of cases, the anterior chamber was oval with a large vertical axis in 74% of cases. The posterior face of an angle-supported IOL must have a 700 microm vault to respect the physiological modifications of the crystalline lens. It is difficult to know the posterior chamber's exact diameter as it varies with the horizontal or vertical axis. It also undergoes constant modifications due to accommodation and aging.

The AC OCT has better reproducibility than the IOLMaster for evaluating the depth or internal diameter of the anterior chamber. This study showed that in 74% of cases, the AC was an oval with a larger vertical axis, which provides evidence of the value of the OCT preoperative examinations for phakic intraocular lens implantation.

Crystalline lens rise should be considered a new safety criterion for Artisan phakic IOL implantation and should also be applied to other types of phakic IOLs. The distance remaining between the crystalline lens rise and a 600 microm theoretical safety level allows one to calculate how long the IOL can safely remain in the eye.

Anterior segment optical coherence tomography is a new method to explore the anterior chamber. The target can be focused and defocused with positive or negative lenses to reproduce the conditions of natural accommodation. We studied accommodation in an albino patient because the absence of pigment allows the infrared beam to penetrate the iris and explore the modifications of the ciliary body and the crystalline lens during natural accommodation in a human subject.