[Preventive iridotomy--a prospective study].

Purpose: To evaluate the mid-term efficiency of laser peripheral iridotomy (LPI) in preventing intraocular pressure (IOP) increase and angle closure in the fellow eye after acute primary angle closure glaucoma.

Method: prospective, noncomparative, interventional case series--29 consecutive cases with acute primary angle closure glaucoma on presentation were enrolled in the study in 2001. Mean follow-up time: 14 months (12-18 months).

Presentation: assessment of IOP and gonioscopy of the fellow eye; LPI of the fellow eye within 24h of presentation. IOP assessment of the fellow eye thrice a day until discharge. Gonioscopy of the fellow eye at discharge. One month later: visual field; optic nerve head evaluation of the fellow eye after pupil dilation; IOP monitoring until pupil recovery. IOP assessment on a monthly basis.

Results: 2 patients presented with bilateral angle closure attack; 2 patients presented with angle closure attack of the second eye, which had not received adequate preventive treatment; 1 patient developed angle closure of the fellow eye immediately after the initial gonioscopy but was promptly managed with LPI; 7 patients had IOP > 21 mm Hg of the fellow eye on presentation, required medication after LPI but did not develop acute angle closure during the follow-up; 17 patients had normal IOP of the fellow eye, remained normal during the follow-up and did not require medication.

Conclusion: LPI is highly efficient in preventing acute angle closure in the fellow eye; in the eyes that were normal on presentation, LPI also prevents later IOP increase.