Filtering blebs, though intentionally produced in glaucoma surgery can occur unintentionally after an uneventful cataract surgery.1 Spontaneous resolution of these blebs can occur.1 Continued presence of these blebs can have grave consequences such as intraocular infection2 and maculopathy due to hypotony.3
A sixty-two year old lady presented with complaint of a white mass in upper part of her left eye, two months following cataract surgery. She noticed the mass one week following surgery, which gradually increased in size over 2-3 weeks. She had no history of glaucoma, any other intraocular surgery or trauma in the past.
On examination, her best-corrected visual acuity (BCVA) was 6/24, N10 in the right eye and 6/9,N6 in the left eye. The intraocular pressure (IOP) was 12 mmHg in both eyes. Slitlamp examination of the left eye showed a cystic elevated conjunctival bleb resembling a Tenon's cyst at 12 o'clock limbus. (Figure 1a) It was firm in consistency and did not collapse on massage over the bleb. The anterior segment was quiet with a posterior chamber (PC) intraocular lens implant. Gonioscopy showed open angles in both eyes with fishmouthing of internal incision in left eye
Figure 1b. On fundus examination with dilated pupil no abnormality was noted in the retina, and the disc showed a cupping of 0.2:1 with healthy neuroretinal rim in both the eyes. Based on the above findings, a diagnosis of left eye pseudophakia with post-cataract filtering bleb was made and it was decided to resuture the wound.
Intraoperatively, conjunctiva was found to be freely mobile over the bleb surface. A fornix based conjunctival incision was taken; the conjunctiva was dissected posteriorly over the bleb surface exposing a tense, opalescent bleb with a thick wall. As the Tenon's capsule was punctured for excision, the aqueous leaked out, the bleb collapsed with shallowing of the anterior chamber (AC) indicating that the bleb was in direct communication with the anterior chamber. The remnant Tenon's capsule was excised and a linear external scleral incision was seen. The plane of the scleral tunnel was identified by blunt dissection. The superficial sclera over the tunnel had been converted to a scleral flap by the previous surgeon by creating two radial incisions on either side of the tunnel. The external incision measured approximately 7mm in length. On lifting the scleral flap, the internal incision was seen just in front of the surgical limbus, indicating premature entry into the AC. A horizontal stitch using 10-0 monofilament nylon was taken to appose the scleral flap to the scleral bed. Absence of wound leak was confirmed by pressing on the posterior lip of the scleral incision4 as described by Anders et al.4 Conjunctiva was sutured to the limbus with 2 interrupted 8-0 vicryl sutures. Postoperatively a topical 0.3% tobramycin sulphate and 0.1% dexamethasone sodium phosphate combination eye drop were prescribed in tapering doses. On postoperative day 1, filtering bleb in the left eye was absent (Figure 2a), the wound was well apposed; Seidel's test was negative, and the IOP was 10 mmHg. At the follow-up two months later, the BCVA of left eye was 6/9, N6, IOP was 12 mmHg and the gonioscopy showed absence of fishmouthing of internal incision. (Figure 2b)
Sutureless technique for cataract surgery has gained wide acceptance. Internal incision gape occurs because of improper wound construction such as premature entry into the anterior chamber at or behind Schwalbe's line, irregularity of the internal incision such as a curvilinear design, or an extension toward the limbus forming a tongue or flap of tissue resulting in internal wound gape which is termed "fishmouthing" of the internal incision.5 If left uncorrected, internal wound gape has been known to cause delay in primary wound healing with aqueous egress to the deep portion of the tunnel and subconjunctival space5 as in this case.
Intraoperative recognition of wound leak may be essential to prevent inadvertent filtering bleb. Shallowing of AC with passive fluid leak at the scleral incision site on injecting BSS through paracentesis indicates wound leak. Irrigation with BSS inside the scleral tunnel may remove possible nuclear and cortical fragments or viscoelastic that may prevent apposition of the internal lip of the wound. Infiltration of BSS into the corneal stroma at the ends of the wound with a blunt-tipped cannula hydrates and expands the lamellae, creating a self-sealing wound. Alternatively, AC can be deepened by injecting air through the paracentesis. This often raises IOP enough to close the internal lip of the wound . Radial or horizontal sutures6 can also close the scleral tunnel incision. Closure with radial sutures creates tangential forces that cause misalignment of both the internal and external aspects of the wound and corneal instability and possibly lead to internal wound gape. Horizontal sutures, on the other hand, close the incision by suturing the roof of the scleral tunnel to the floor, flatten the scleral tunnel, allowing a more tight closure of the tunnel and internal incision.
The reported incidence of inadvertent filtering blebs following cataract surgery ranges from 1% to 7.7%.7 We failed to find any report of inadvertent filtering bleb following sutureless cataract surgery on Medline search. A decrease in the incidence of inadvertent blebs to 0% with advent of phacoemulsification has been reported.8
While such blebs are asymptomatic, patients may complain of irritation or visual disturbances. Internal incision gape may cause permanent wound slippage and late induced against-the-rule-astigmatism. It has been postulated that postoperative endophthalmitis may occur when bacteria enter the eye via the unsealed incision.2 Because of the potential for devastating complications, any patient with a shallow anterior chamber, hypotony, or macular oedema with a clinically significant bleb persisting for more than 2-3 months or with ocular irritation needs a bleb repair.
Learning sutureless technique for cataract surgery is on an upward trend among young surgeons. New surgeons should learn to be able to create well-constructed wounds that seal both externally and internally. The author by reporting this case highlights the use of gonioscopy to visualise and evaluate the internal wound. Intraoperative recognition of internal leak and its management, with the advantage of horizontal sutures is to be kept in mind.
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