Rose Bengal PDT does not improve BSCVA in infected eyes

Adjunctive Rose Bengal (RB) photodynamic therapy (PDT) shows no benefit in the treatment of fungal, Acanthemoeba, and smear- or culture-negative infectious keratitis, according to a study.

A total of 330 patients with corneal ulcers were randomized 1:1 to receive either topical antimicrobial therapy plus RB PDT or topical antimicrobial therapy plus sham RB PDT.

Best spectacle-corrected visual acuity (BSCVA) at 6 months was the primary outcome. Secondary outcomes were as follows: BSCVA at 3 weeks and 3 months; infiltrate, scar size, or both at 3 weeks, 3 months, and 6 months; and corneal perforation (CP), the rate of therapeutic penetrating keratoplasty (TPK), or both; and microbiological cure rate.

Filamentous fungus (n=301, 91 percent) was the most common isolated organism, followed by Acanthemoeba (n=10, 3 percent). Nineteen patients (6 percent) had negative culture or smear findings.

RB PDT did not demonstrate any improvement in BSCVA at 6 months relative to sham treatment (‒0.0004, 95 percent confidence interval [CI], ‒0.13 to 0.13; p=0.62).

However, there was evidence of a statistically significant interaction between the treatment arm and fungal organism with regard to BSCVA (p=0.02). RB PDT improved BSCVA among eyes with Fusarium infection (difference, ‒0.17 logMAR, 95 percent CI, ‒0.37 to 0.03) but worsened BSCVA among eyes with Aspergillus infections (difference, 0.39 logMAR, 95 percent CI, ‒0.03 to 0.80).

At 3 weeks, scar size was smaller by 0.45 mm (95 percent CI, ‒0.76 to ‒0.45; p=0.004) in the RB PDT arm, but this did not remain statistically significant at 3 and 6 months. Furthermore, no significant between-group difference was noted in the rates of CP, TPK, or microbiological cure.

“We were unable to find a benefit of adjuvant RB PDT overall,” the investigators said. “Future directions may include trying alternative photosensitizers or other treatment algorithms.”