Inadvertent perforation of the globe is a well-recognized complication of eye muscle surgery. In the 1960s and 1970s, it was estimated to occur in 9% to 12% of strabismus surgeries.1'3 Smaller, more recent prospective studies suggest the rate to be in the 1.5% to 2.8% range,4,5 and one large, retrospective, survey-type report has placed the incidence of recognized perforations as low as 0.13%.6
We designed a prospective study to determine the frequency of suspected and unsuspected retinal perforations and choroidal injuries during routine horizontal strabismus surgery performed in a university teaching setting.
All children 18 or younger having horizontal strabismus surgery between September 1, 1992, and October 31, 1995, underwent funduscopy using an indirect ophthalmoscope immediately following the conclusion of the surgical procedure. Phenylephrine 1% to 2.5% routinely used at the onset of surgery to help with hemostasis usually provided adequate dilation by the end of surgery. Occasionally, an additional drop of 1% tropicamide or 1% cyclopentolate was applied to give an adequate view of the periphery. All procedures were performed using a spatulated needle and a 6.0 polyglactin suture. Surgery was performed by both the resident and attending physician, with the latter performing the fundus exam. The protocol sheet was completed by the attending physician (Fig). We purposely avoided documenting who, resident or attending, performed each muscle procedure.
To avoid confounding variables, patients with myopia greater than -6.00 diopters or connective tissue disorders where scierai thickness could be abnormal and patients undergoing reoperation were excluded. An incident was documented as a suture track if a disruption of the choroid could be identified, as opposed to a retinal perforation, identified by a frank retinal hole with or without retinal hemorrhage or vitreous loss.
Fig: Protocol sheet completed at end of each surgery by attending physician.
Elective strabismus surgery was performed on 765 children who underwent 1 129 horizontal muscle recessions and 349 horizontal muscle resections. An additional 161 vertical or oblique muscle procedures were performed. Intraocular Undings were identified in 14 patients. Three patients had a frank retinal perforation, and 11 patients had fine choroidal changes at about the site of muscle reattachment. All three retinal perforations were suspected prior to inspection, as were 7 of the 11 cases of choroidal changes.
In this prospective study of 765 children undergoing strabismus surgery on previously unoperated horizontal recti muscles, the incidence of chorioretinal injury was 1.8% (14 of 765) per case and 0.9% (14 of 1 478) per horizontal muscle. The rate of retinal perforation was 0.4% (3 of 765) per child and 0.2% (3 of 1 478) per horizontal muscle. The risk of choroidal injury without perforation was 1.4% (11 of 765) per case and 0.7% (11 of 1 478) per horizontal muscle.
The overall risk of intraocular injury in the 765 children who underwent a total of 1645 muscle procedures is 0.85% (14 of 1 639) and the risk of perforation is 0.2% (3 of 1639). The risk of choroidal injury without perforation was 0.6% (11 of 1639).
Two retinal perforations were treated with observation only, with one being given an injection of gentamicin 10 mg subconjunctivally and the second receiving 10 mg of gentamicin subconjunctivally and oral ampicillin for 10 days. The third child was assessed by a retinal specialist at the time of surgery, and light cryotherapy was applied to the perforation site. This patient also received 10 mg of subconjunctival gentamicin and oral amoxicillin for 10 days postoperatively.
No retinal detachment or endophthalmitis developed in any of our 765 patients, who were followed for a minimum of 6 weeks postoperatively. Although a perforation can occur at any step of strabismus surgery,6 all three perforations occurred at the time of needle passage through the sclera during a recession of a horizontal muscle.
As underlined by the small number and lack of uniformity in dealing with our retinal perforations, we cannot make a recommendation as to the use of cryopexy or antibiotics when faced with a frank retinal perforation. Although each case must be assessed on an individual basis with treatment depending on the extent of retinal injury, the literature indicates that should cryotherapy be deemed necessary, it should be applied sparingly.7,8 Similarly, although the role of subconjunctival, topical, and oral antibiotics is not well defined in these instances, their use certainly seems prudent.
Although our study indicates that with the use of spatulated needles, meticulous dissection, and good exposure, the risk of chorioretinal injury and perforation are low, the possible consequences of these complications cannot be underestimated.
The most serious sequelae of scierai perforation are retinal detachments,9 endophthalmitis,10 and phthisis bulbi11; other, less devastating consequences such as cataracts, ectopia lentie, and glaucoma also have been documented.
In view of our findings, we would recommend indirect ophthalmoscopy at the end of all strabismus surgeries where the surgeon suspects a perforation. If a perforation is identified, close observation is necessary, although conclusions on the preferred management of each case cannot be extrapolated from this study.
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