We thank Drs Hafezi and Kling for their comments regarding our recent publication.
Despite intensive medical treatment being used, moderate to severe infectious keratitis usually leads to visual loss. The purpose of our study is to evaluate the efficacy of photoactivated chromophore for infectious keratitis (PACK-CXL) as an adjunct to medical treatment for patients with infectious keratitis at the initial presentation. We hypothesized that PACK-CXL treatment, which induced death of microorganisms and reduced the infectious load, especially in the anterior 300 μm of the cornea, hastened the resolution of infectious keratitis when combined with medical treatment.
We evaluated the primary outcome as the size of stromal infiltration, which typically improves according to the response to treatment. The size of epithelial defect does not reflect the response to treatment in fungal keratitis cases, which can present with intact epithelium while the fungal ulcer spreads beneath it.
Unfortunately, we did not find any additive effect of PACK-CXL to medical treatment. Even though the sample size was small, we did calculate the sample size and have already shown this calculation in the methodology section. To our concern, it might not have enough firm evidence that supports the study of PACK-CXL without medical treatment, especially in patients with severe infectious keratitis.
Sodium fluorescein is a commonly used dye to evaluate the size of corneal epithelial defect. The maximum absorption spectrum of sodium fluorescein ranges from 474 to 500 nm, which does not overlap the wavelength of 365 nm used in the PACK-CXL. However, regarding the in vitro study that showed the reduction of antimicrobial effect when putting the fluorescein and riboflavin together, the PACK-CXL treatment in our study was done at least 3 hours after fluorescein instillation.