We thank Professor Oguz for commenting on our paper. While dysesthetic blebs following glaucoma drainage surgery contribute to symptomatic ocular surface disease (OSD), there is little data regarding the specific etiology. It is likely to be multifactorial. Budenz and associates, investigating 97 patients with unilateral trabeculectomy blebs, found that young age, bleb exposure in the interpalpebral fissure, height of the bleb adjacent to the cornea, and bubbles in the tear film on blinking were predictive of dysesthesia. Only 2 patients had adjacent dellen and 6 an epithelial defect; hence, no significant results were obtained regarding these proposed mechanisms. Surprisingly, the type of antifibrotic agent used (none, 5-fluorouracil, or mitomycin C) was not predictive of dysesthesia, as these agents may lead to limbal stem cell damage.

Corneal tear film disturbances from adjacent and overhanging perilimbal protrusion of the bleb, exacerbated by local thinning, are likely to contribute to symptoms of OSD. Ectopic and thinned menisci adjacent to the bleb may accompany tear film instability, and disruptions of the upper meniscus may be associated with bubbles in the tear film on blinking described above. The use of optical coherence tomography and video-meniscometry to dynamically evaluate tear menisci in patients with blebs is likely to provide key insights into the pathogenesis of bleb dysesthesia and OSD. As mentioned by Dr Oguz, preservative-free lubricants of low viscosity during the day and high viscosity at night often provide relief for patients with bleb-related dysesthesia.