We thank Fernandes and associates for their interest in our study and for actually using our method clinically in their cataract surgeries. For periocular disinfection, 10% povidone-iodine is used in Japan, while 5% povidone-iodine is widely used in American and European countries. For conjunctival disinfection, 1% to 5% povidone-iodine is generally used. However, Jiang and associates observed frequent occurrence of corneal epithelial edema in patients when 5% povidone-iodine was used to irrigate the conjunctiva. When they performed studies on rabbits, instillation of 10 drops (0.5 mL) of 2.5% povidone-iodine caused corneal epithelial damage and injection of 0.05 mL of 1.5% povidone-iodine into the anterior chamber resulted in corneal endothelial damage. From these results, they recommended to use 0.5% or 1.0% povidone-iodine for disinfection of the surgical field. Based on detailed investigations, Trost and associates concluded that the concentration range of 0.05% to 0.5% povidone-iodine is safe to ocular tissues and highly bactericidal.

Fernandes and associates used 2.5% povidone-iodine for preoperative disinfection of the operative field. This is a concentration that is toxic to the corneal epithelium. We presume that after corneal epithelial damage was induced by 2.5% povidone-iodine at the beginning of the operation, subsequent repeated irrigation with 0.25% povidone-iodine might have aggravated the corneal epithelial damage, resulting in their observation of superficial punctuate keratopathy. As described in our report, we use 0.25% povidone-iodine also for preoperative disinfection of the operative field. During operation, we repeatedly irrigate the conjunctiva with 0.25% povidone-iodine in the same way as the conventional practice of washing the conjunctiva with saline. So far in our department of ophthalmology, we have used 0.25% povidone-iodine routinely in 3000 cataract surgeries, 500 buckling surgeries for retinal detachment, and 1500 25-gauge vitrectomies. No postoperative endophthalmitis occurred in any of the operated eyes. Furthermore, we have not encountered any corneal epithelial damage or corneal endothelial damage that can be attributed to 0.25% povidone-iodine, proving that this method is a highly safe disinfection method that can be used routinely.