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Editor,—Herpetic canaliculitis is rare. A report in the British literature suggests, however, that it is more common than is generally appreciated.1 The condition has been recognised as a distinct clinical entity only recently.2Bouzas3 found canalicular involvement in one out of 12 patients with primary ocular herpes simplex infection and estimated the incidence at about 8%. Among 130 cases of canalicular obstruction Coster and Welham1 considered herpes simplex infection the responsible agent in 20 cases, being 15%. We would like to report on an additional two cases of stenosis of the lacrimal canaliculi in the course of primary herpes simplex infection.
The cases were virtually identical except for the age of the patients, respectively 14 and 12 years, and the eyes involved, respectively the right and the left eye. Both patients presented with a primary herpes simplex infection. On the skin of the eyelids and on the lid margin vesicles surrounded by a hyperaemic area were observed (Fig1).
Initially, the content of the vesicles was transparent, but later the intravesicular fluid became turbid and after rupture of the vesicles, ulcers, and crusts, particularly on the lid margin, developed. There was oedema of the eyelids and preauricular lymphadenopathy as well as a follicular conjunctivitis and epithelial keratitis with lacrimation.
Herpes simplex type 1 virus was isolated in both cases. Lacrimation persisted well beyond the resolution of the acute inflammatory signs and therefore canalicular obstruction was suspected. There appeared to be a stenosis in the upper and the lower canaliculus on the affected side. The stenosis was in the mid portion of the canaliculi starting at about 5 mm from the punctae.
Up until now a total of 37 cases of canaliculus stenosis in the course of primary herpes simplex infection have been reported. In Table 1 the characteristics of the cases are shown. There is a strong preponderance for females to contract stenosis of the canaliculi in the course of a primary herpetic infection. Most patients were under the age of 20 years; this is not surprising as primary herpetic infection is a disease of youth. There are two peaks of the infection; the first is between 0.5 and 5 years. At the age of 5, 60% has been infected with herpes virus. The second peak is in adolescence; at the age of 20 years 90% are infected with HSV.
Herpes simplex is an intracellular parasite. The canaliculi have a very narrow lumen, the diameter being estimated to measure 0.5 mm in the horizontal portion, and are lined by non-keratinised stratified squamous epithelium continous with that of the conjunctiva. Infection of the canalicular epithelium with subsequent exfoliation, apposition of the tissues, inflammatory oedema, and subsequent cicatrisation before epithelial regeneration occurs, would result in stenosis.
As stenosis develops during the course of the primary herpes simplex infection, and as the cultures are positive for HSV, there is strong circumstantial evidence that the obstruction is a direct consequence of viral infection of the epithelium of the canaliculi. In fact, Coster and Welham1 demonstrated, using electron microscopy, in biopsy specimen particles with a size and morphology compatible with HSV.
Freeman et al 4 never found total occlusion of the canaliculi in acutely herpes simplex infected rabbits. They doubted, from the lack of ductal epithelial damage in their animal model, the mechanism proposed by Harris et al 5 to explain canalicular obstruction. As canalicular obstruction is a well recognised complication of primary herpetic ocular infection in humans it seems more likely that Freemanet al did not use a suitable animal model.
Moreover, Kaufman et al 6 pointed out that disease patters in HSV infection were, to a large degree, dependent on strain specific differences in the amount and types of glycoprotein produced, which is manifested by differences in virulence and antigenity.
We believe that the incidence of canalicular stenosis may be higher than can be inferred from the published cases because if only one canaliculus is obstructed the condition probably escapes attention.
We feel very strongly that all patients with ocular primary herpes simplex infection should be prophylactically intubated with silicone lacrimal stents in order to prevent herpetic cicatricial canalicular stenosis.