Trypan blue-guided trabeculectomy revision

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Correspondence: Mr K N Rajkumar Email:
Email: rajkumarkadaba@hotmail.com Bridgend Eye Unit, Princess of Wales Hospital, Coity Road, Bridgend, CF31 1RQ. Tel: 01656 752752; Fax: 01656 754156.

Date of acceptance: January 25th 2008

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Introduction

This case describes the use of trypan blue in a pseudophakic patient undergoing drainage of a choroidal effusion. The use of trypan blue in ophthalmology dates back more than three decades.1 It is used widely to stain the anterior capsule during cataract surgery and in vitreoretinal surgery to aid visualisation of epiretinal and internal limiting membranes.2-4

Case Report

An 85-year-old patient with primary open angle glaucoma and a previous trabeculectomy (OS) underwent bleb needling with 5 Fluorouracil due to a progressive rise in intraocular pressure (IOP). Her IOP did not respond to the needling and remained at 20mmHg during the following two weeks. She presented to the clinic three weeks post-needling with visual acuities of 6/9 OD and perception of light OS. She was noted to have a diffuse conjunctival bleb, a shallow peripheral anterior chamber and an IOP of 14mmHg in the left eye. No aqueous leak was detected. Fundoscopy revealed extensive choroidal detachments. In the absence of hypotony, a cyclodialysis cleft was suspected and gonioscopy was performed. The view of the angle however was obscured due to the shallow peripheral chamber. Her right eye was controlled on topical treatment and stable. Over the next few days the IOP in the left eye gradually reduced to 7mmHg and she developed kissing choroidals. The bleb and anterior chamber remained stable suggesting a possible ciliary body detachment. A decision to drain the choroidal effusion was made.

Drainage of the choroidal effusion and bleb exploration was carried out with the use of trypan blue 0.1%. The dye was injected into the anterior chamber and noted to appear beneath the conjunctival bleb delineating the area of previous needling. This suggested a possible over-drainage of aqueous and exploration of the scleral flap was carried out. A raised edge of the flap was identified and thereafter secured with a 10.0 nylon suture. A single sclerotomy was made 8mm from the limbus and straw-coloured transudate was drained. Following 30 minutes of drainage, no trypan blue staining was seen within the drained fluid confirming the absence of any communication with the anterior chamber and thus excluding a cyclodialysis cleft. The small residual choroidal effusions resolved completely over the next two days and her visual acuity gradually improved to 6/9 over the next three months.

Discussion

Healey and Crowston have described the mixing trypan blue with antimetabolites in glaucoma surgery such that the area of treatment can be delineated.5 Its use has also been described in determining the patency of trabeculectomies during cataract surgery.6 In both these reports, no adverse reactions have been reported and the dye did not visibly persist more than 24 hours following surgery. Its persistence following staining of the anterior capsule in phakic eyes is not known, however, it may be effectively used in pseudophakic eyes as demonstrated in this case. Its use as an adjunct during drainage may be particularly useful in atypical cases of choroidal effusions. Over-drainage of aqueous or the presence of a cleft may be identified, both of which can be addressed intra-operatively.

References