Botox can help with squint problems after surgery for glaucoma

COS 2012, July 5 - Botulinum toxin (Botox) can be used as an alternative to eye muscle surgery to correct a squint in patients who have previously had glaucoma drainage surgery, according to researchers from the United Kingdom.

Chloe Lafferty, from Moorfields Eye Hospital, London, reported details of a retrospective study of patients who underwent glaucoma drainage surgery. Drainage tube implants were the most frequent procedure, but trabeculectomy was also performed. Findings were presented at the XIIth International Orthoptics Congress in Toronto.

"Patients with glaucoma severe enough to require drainage surgery may develop a secondary squint," she said. The medical literature shows that strabismus following implantation of drainage devices occurs in 6% to 100% of cases. Eye muscle surgery is a way to treat strabismus, but could lead to conjunctival scarring, which can potentially cause drainage failure and subsequently raise intraocular pressure (IOP).

Researchers analyzed data from their toxin database for a 12-year period (2000-11) on patients who underwent surgery for glaucoma at the centre. A total of 277 patients had secondary squint. Of these, 21 (7.6%) had glaucoma (11 male, 10 female) and had received a mean of 3.5 Botox injections. The group was subdivided into three categories: those who had not undergone drainage surgery, those who had drainage implant(s) and those who had had trabeculectomy.

A total of 17 patients were found to have exotropia (eyes that turn outward), while four had esotropia (one or both eyes turn inward). Eleven had an associated vertical deviation from the strabismus. Lafferty noted that Botox does not cause scarring and works as an alternative to surgery.

"We have found repeated toxin treatment to have a useful long-term role in the management of strabisumus with no risk to IOP control," she said.

Data pertaining to IOP were not presented.