[Effect of traumatic iris defects on spatial perception].

Perforating injury to the eye often results in iris defects in addition to loss of the lens. To determine whether iris defects can impair stereopsis, we tested the stereoscopic vision of 23 patients treated at the University Eye Clinic in Kiel for perforating eye injuries involving the iris and, in most cases, the lens. The patients were divided into three groups according to the severity of the iris defect and the status of the intraocular lens. Individuals with strabismus or visual acuity < 0.5 (20/40) were excluded. Stereopsis was measured using conventional stereopsis tests (Titmus contour stereopsis, Lang global stereopsis) and by means of the Pulfrich pendulum phenomenon. Patients with traumatic aphakia without an iris defect (n = 33) served as controls. Optical rehabilitation was achieved in the controls lenses (n = 16) or intraocular lens implant (n = 17). In group I (intact lens, iris defect < 135 degrees), two of five patients had attained global stereopsis. In group II (implanted or contact lens, iris defect < 135 degrees), only one of the nine patients exhibited global stereopsis. In group III (no lens, iris defect > 135 degrees), none of the nine patients achieved global stereopsis. In the control group, by contrast, more than half of the patients with an implant (10 of 17) and 3 of 16 patients with a contact lens attained global stereopsis. The results indicate that severe iris defects are especially likely to impair stereoscopic vision, more so than traumatic loss of lens alone without an accompanying iris defect.