Does head positioning influence anterior chamber depth in pseudoexfoliation syndrome?

Purpose: Phacodonesis can occur in pseudoexfoliation syndrome because of im paired zonular support. This study investigates whether the increased mobil ity of the lens influences anterior chamber depth in patients with pseudoex foliation while assuming a prone position. Methods: Central anterior chamber depth was measured in 39 patients with cl inically apparent unilateral pseudoexfoliation and elevated intraocular pre ssure. Patients were placed in a face-up position for 5 minutes, at which t ime anterior chamber depth and axial length were measured by A scan, and in traocular pressure was measured by Tonopen (Oculab, La Jolla, CA) in both e yes. The measurements were repeated on both eyes after 5 minutes in a face- down position. Results: No significant differences in intraocular pressure or axial length between the prone and supine positions were found in either eye. Anterior chamber depth in eyes with pseudoexfoliation decreased from a mean of 3.08 mm in the supine position to a mean of 2.95 mm in the prone position, where as mean anterior chamber depth in the fellow eyes decreased from 3.01 mm to 2.97 mm, The decrease in anterior chamber depth when facing down in the ey es with pseudoexfoliation was significantly greater than in the fellow eyes . Conclusions: In patients with clinically apparent unilateral pseudoexfoliat ion, the lens seems to be more mobile in the affected eye, This results in a shallower anterior chamber when the head is placed in a prone position. W hether this bet might potentially lead to transient pupillary block when en gaging in activities such as facing down while reading warrants further stu dy.