We were extremely interested to read the comments from Patel and associates in response to our article, “Long-term Complications Associated with Glaucoma Drainage Devices and Boston Keratoprosthesis.” We appreciate the insight they provide regarding their experiences at the Massachusetts Eye and Ear Infirmary with glaucoma drainage device (GDD) erosions and Boston keratoprosthesis surgery.

It is of particular interest that they observed 19 cases of conjunctival erosion over GDDs. This accounts for 14.6% of their patients with both a Boston keratoprosthesis and a GDD over the past 5 years (n = 130). This is not an insignificant complication rate in these patients. Before the publication of our findings at the University of California, Davis, the literature has been quite sparse regarding this particular complication of keratoprosthesis surgery, with only one other report of conjunctival erosions over tube shunts. Given our findings and this subsequent report by Patel and associates, we speculate that this is an underreported complication of Boston keratoprosthesis surgery.

Their suggestion of changing the diameter of the contact lens in cases where mechanical trauma from the contact lens may be contributing to the GDD erosion is a valuable one. Their resolution rate of 37% with this simple adjustment is encouraging. Cortina and associates also suggested placing a more posterior pars plana tube with a lamellar corneal patch graft to decrease and eliminate friction between the contact lens edge and the tube and to prevent such erosions from occurring entirely.

One reservation we have regarding the suggestion by Patel and associates to observe stable erosions in patients without leaks, hypotony, or discomfort is the continued concern for potential ocular infections. We certainly agree that daily prophylaxis with a combination of topical vancomycin and another broad-spectrum commercially available topical antibiotic decreases the risk of bacterial endophthalmitis. However, it does not address the increasing concern of potential fungal infections in these patients. Fungal infections have increased since the use of broad-spectrum antibiotic prophylaxis, and therapeutic contact lenses have been recommended. Although low, the risk of a devastating complication associated with fungal colonization of an eroded GDD is not negligible.

Ultimately, the key for management of these patients is a multidisciplinary approach to their care. Close coordination between the corneal surgeon and the glaucoma specialist involved in the follow-up of these patients will determine whether observation or surgical intervention is most appropriate in each individual case.

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Jan 12, 2017 | Posted by in OPHTHALMOLOGY | Comments Off on Reply

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