Half of Orbital Infection, Endophthalmitis Cases Present Within Five Days of Strabismus Surgery

When evaluating the median time to presentation for complications following strabismus surgery, this study found that endophthalmitis and orbital cellulitis present the quickest at five days, while corneal ulcers (pictured) and lost/slipped muscle occurred on days 16 and 14, respectively. Photo: Joseph Stamm, OD. Click image to enlarge. While strabismus surgery is typically a safe procedure, incidence rates of complications are typically drawn from research that includes a relatively low number of patients, prompting the need to study a larger database. In a recent study, researchers aimed to identify occurrence rates and associated risk factors of major complications following strabismus surgery over a nine-year period. They noted that this is the largest dataset ever to evaluate complication rates after eye muscle surgery.The findings, reported in Ophthalmology, revealed that nearly half of orbital infection and endophthalmitis cases occurred within five days of surgery. Because of this, the authors suggest that surgeons schedule at least one contact point with postoperative patients during this timeframe to facilitate early diagnosis and management of any serious complications. Included in the study was a total of 89,339 patients from the Intelligent Research in Sight (IRIS) registry who underwent surgery on 134,635 eyes between January 2013 and December 2021 and experienced a major complication within 60 days of the procedure. Subjects’ diagnostic and procedural codes for eye muscle surgical procedures and postoperative occurrence of bacterial keratitis, orbital infection, endophthalmitis and surgery for lost or slipped muscle were analyzed. One or more of the four surveyed complications occurred in 0.115% of patients. Corneal ulcers occurred in 0.03%, endophthalmitis in 0.01% and orbital infection and lost/slipped muscle in 0.04% each. Approximately half of the cases of endophthalmitis and orbital infection presented within five days of surgery.Independent risk factors for any complication were combined vertical and horizontal muscle surgery (as opposed to horizontal or vertical alone) and number of add-on procedural codes. The complication rate was highest (1.15%) for patients with three add-on CPT codes, and the rate of any complication for combined horizontal and vertical procedures was 0.14%, compared to 0.07% for horizontal muscle surgery only.Rates of lost/slipped muscle and corneal ulcers increased steadily throughout the different age groups, while orbital infection was similar across all ages. Endophthalmitis was rare with only one case but became more common in the over-65 group. The authors noted that female sex is a possible risk factor for this complication.Visual loss was present in a majority of patients with complications; notably, it was significant in cases of endophthalmitis (five to six Snellen lines) but minimal in the other complications (less than one line). “Mechanisms of visual acuity loss in endophthalmitis or central corneal ulcer are intuitive, but we cannot ascertain from the data set the etiologies of decreased vision from the other complications,” the authors wrote in their paper. However, they continued, “one could postulate that orbital cellulitis or complex surgery for a lost muscle could be accompanied by optic neuropathy; worsening amblyopia may be a factor as well in some cases.”There were several limitations to this study. Due to the limited nature of data in the IRIS Registry and inability to identify individual patients, it wasn’t possible to review individual charts to determine additional potential risk factors, medical history, temporal profile or ocular comorbidities. Additionally, there may be discrepancies in how physicians interpret and use CPT or ICD codes. “For example, we cannot distinguish between a truly lost vs. slipped muscle, or an early over- or undercorrection,” the authors explained. “The exact delineation between preseptal and orbital cellulitis, or corneal abrasion/delle and early infiltrate, cannot always be reliably determined.”Researchers also did not evaluate rates of less serious complications, such as conjunctivitis or suture reactions, as coding for these is likely very non-standard and inconsistent. Lastly, there may be some simple typing errors in the documentation of procedures and complication codes (e.g., 67311 vs. 67331); however, in a large database such as this, it is likely that the variety of errors that may have occurred had balancing effects on the means.Nevertheless, this data can be incorporated into discussions during the informed consent process for eye muscle surgery and may allow better counseling to address patients’ and families’ questions regarding the nature and frequency of potential major complications, which may be vision-threatening and require additional treatment or surgery, the authors wrote.Click here for the journal source. Siatowski RM, Morse CL, Gold RS, et al. Major complications following strabismus surgery: nine-year data from the IRIS (Intelligent Research in Sight) Registry. Ophthalmology. November 21, 2025. [Epub ahead of print.] This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.