Sir,

We report a case of delayed onset spontaneous conjunctival filtering bleb appearing many years after penetrating trauma. The bleb fistula site was identified on ultrasound biomicroscopy (UBM), but was not apparent on clinical examination.

Case report

A 68-year-old man presented after noting a growth on the nasal aspect of his right eye conjunctiva 1 month ago. The growth did not increase in size, and was not associated with ocular or visual symptoms. He reported history of penetrating injury to that eye with glass during adolescence that required surgical repair at the time.

In the right eye, best-corrected visual acuity was 20/25, applanation tonometry was 19 mm Hg. Biomicroscopy revealed a conjunctival cystic bleb nasally (3–4:30 O'clock) in proximity to a corneal-limbal scar (Figure 1). The anterior chamber was shallow nasally with irido-corneal adhesions and a distorted pupil. The lens showed mild nuclear sclerosis. Gonioscopy of the nasal angle revealed a localized ‘dimpled’ scarring and no cleft (Figure 2). Ultrasound biomicroscopy of the bleb site showed scleral fistulization from the posterior aspect of the bleb to the ciliary body (Figure 3). The rest of his ophthalmic evaluation, including the left eye examination was within normal limits.

Figure 1
figure 1

A localized conjunctival filtering bleb nasally in the right eye.

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Figure 2
figure 2

Gonioscopy of the nasal angle reveals peripheral anterior scarring with dimpling of the iris but no cleft.

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Figure 3
figure 3

Ultrasound biomicroscopy of the bleb shows the posterior communicating fistula (arrow).

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Comment

Spontaneous filtering conjunctival blebs are rare and can be observed in patients with systemic or ocular abnormalities like Terrien's marginal degeneration, Axenfeld syndrome, or familial craniofacial dysmorphism with spontaneous bleb formation.1, 2, 3 Inadvertent blebs at the surgical site of scleral fixated intraocular lenses have also been reported.4

We report an unusual case where spontaneous bleb formation occurred many years after the initial injury. Gonioscopy did not reveal a communication between the bleb and the angle. Rather a posterior channel of communication was apparent on UBM between the bleb and ciliary body. The appearance of blebs on UBM and the association with function have been reported.5 Filtering blebs do pose an increased risk of infection especially if they occur inferiorly or nasally.6 Intervention is not warranted in the absence of aqueous leak, hypotony, worsening of vision or infections. Ultrasound biomicroscopic localization of the fistula is helpful in differentiating a filtering bleb from a possible conjunctival traumatic cyst. It is also useful for surgical planning should future repair become necessary.