• Algorithm for Assessing and Treating Microbial Keratitis

    By Lynda Seminara
    Selected By: Richard K. Parrish II, MD

    Journal Highlights

    American Journal of Ophthalmology, May 2020

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    To guide early management of corneal ulcers, Ung et al. devised a modified version of the 1-2-3-Rule, which they termed 1-2-3-ACT (for 1-2-3 Assess­ment, Culture, Treatment). They found that 1-2-3-ACT lessened the need for culturing after initial deferral in cases with borderline microbial keratitis (MK) and reduced unnecessary cul­tures among the least severe cases. In turn, this lowered costs.

    This retrospective study involved patients with MK treated during two periods: group I (2013 to 2015) had clinician-led decision-making, while those in group II (2016 to 2018) were managed per 1-2-3-ACT.

    The original 1-2-3-Rule has three parameters for performing corneal cultures: 1) ≥1 cell within the ante­rior chamber; 2) infiltrate ≥2 mm; and 3) infiltrate edge within 3 mm of the cornea center. To capture atypical bacterial, fungal, and Acanthamoeba infections, the authors added “and/or ≥2 adjacent lesions” to the second criterion. Patients who met at least one criterion received fortified antibiotic therapy. The main study outcome was any vision-threatening complication.

    The primary analysis set included 665 patients in group I and 767 in group II. A vision-threatening com­plication developed in 12.9% of group I (median follow-up, 67 days) and in 11.2% of group II (median follow-up, 60 days) (p = .51). No meaningful differences in complication rates were found among patients who met zero, two, or three parameters. However, for those with just one parameter, it was more common in group II to culture at presentation (67.7% vs. 54.6% for group I; p = .006) and to start forti­fied antibiotics at that time (53.9% vs. 29.7% for group I; p < .001). The num­ber of vision-threatening complications also was significantly lower in group II (1.8% vs. 9.7% for group I; p = .001). Among patients who did not undergo culture at presentation, culturing was later required for 5.1% of group II and 13.4% of group I (p = .001). The proportion of patients who had tissue sampling despite not satisfying any criterion was lower in group II (8.5% vs. 23.9%; p < .001).

    Multiple logistic regression showed that all three 1-2-3-ACT criteria were strongly and independently associated with clinical outcome, even in a boot­strapped cohort of 10,000 theoretical patients, indicating that the model may be viable for various clinical settings.

    The findings support tissue cultur­ing and antibiotic use at presentation if a corneal ulcer meets at least two of the 1-2-3-ACT criteria. Judging disease severity can be challenging in patients who have just one criterion, said the authors; they emphasized that early aggressive treatment of borderline cases should reduce the risk of vision-threat­ening complications.

    The original article can be found here.