VISUAL OUTCOME AND PROGNOSTIC FACTORS AFTER MAGNETIC EXTRACTION OF POSTERIOR SEGMENT FOREIGN-BODIES IN 40 CASES

Aims-To evaluate the clinical features as well as the visual and anato mical outcome in eyes with magnetic posterior segment foreign bodies, to identify prognostic factors after removal using an electromagnet. M ethods-The records of 40 patients with posterior segment foreign bodie s were retrospectively reviewed for 6 years (1989-94). Post-traumatic cataracts and secondary retinal detachments were treated using convent ional surgical techniques. Pars plana vitrectomy was used only for lat e complications. The mean follow up was 30 months (6-71). Clinical fac tors were studied using univariate analysis. Results-The most common f indings before treatment of these 40 eyes were lens wound, hyphaema, v itreous haemorrhage, and retinal impairment. The foreign body was in t he vitreous (85%) or minimally embedded in the retina (15%). Initial v isual acuity was worse or equal to 20/40 in 70% of the cases. Subseque nt to surgical treatment, a cataract was reported in 60% of the patien ts. Postoperative complications included retinal detachment (15%) and phthysis (5%). The prognosis was worse in cases with intraocular forei gn body of largest diameter greater than or equal to 3 mm, an initial visual acuity less than 20/200, or the presence of post-traumatic reti nal detachment. Presence of initial intravitreous haemorrhage, hyphaem a, or intraocular tissue prolapse did not appear to affect the prognos is. Conclusion-The long term visual acuity results indicated that woun d repair associated with conventional magnet extraction in an emergenc y is a viable treatment for posterior segment magnetic foreign bodies in this selected group. At the time of diagnosis, size of foreign body (<3 mm) and initial visual acuity greater than or equal to 20/200 wer e predictors of good visual outcome after primary magnetic extraction.