To evaluate the effects of prone positioning on the critical distance (CD) in Artiflex (Ophtec BV) foldable anterior iris-claw phakic intraocular lens (pIOL)-implanted eyes.

Twenty patients with 40 Artiflex-implanted eyes were prospectively enrolled in the present study. The nasal and temporal critical distances (CD) were measured with Visante anterior segment optical coherence tomography (OCT, Carl Zeiss, Dublin, CA) in both the sitting and prone positions.

The mean nasal CD was 1.52 ± 0.15 mm in the sitting position and 1.49 ± 0.13 mm in the prone position ( p = 0.01). The mean temporal CD was 1.63 ± 0.17 mm in the sitting position and 1.63 ± 0.16 mm in the prone position ( p = 0.67). In a multiple regression analysis, the changes in nasal CD were positively correlated with anterior chamber volume (r = 0.27; p = 0.01) and negatively correlated with pupil size (r = -0.23; p < 0.01).

Prone positioning can induce a decrease in the nasal CD in Artiflex-implanted patients, especially in subjects with small pupils and large anterior chamber volumes.