The narrowing or occlusion of the external opening of the lacrimal canaliculus leads to punctal stenosis. This should be distinguished from punctal agenesis, which is a congenital condition (Fig 1). It may also be associated with occlusion of the common canalicular duct. Patients usually present with symptoms of excessive tearing. The incidence of this condition is variable, ranging from 8% to 54.3%.
Anatomically, lacrimal puncta are located at the nasal end of the palpebral margin. The upper punctum is located 1mm medial to the lower punctum. Upper and lower puncta approximate each other when the eyelids are closed. The puncta open into the tear layer and lead into the lacrimal duct, lacrimal sac, and nasolacrimal duct. The papillae containing the puncta are surrounded by the Riolan muscle fibers and a fibrous ring. Normal punctal size ranges from approximately 0.2-0.5mm. One study determined the criteria for punctal stenosis: the punctum is less than 0.3mm, or there is an inability to cannulate the punctum with a 26G cannula without dilation. Based on the shape of the external punctum, punctal stenosis is of four types:
Membranous (31%) Fig 2
Slit type (13%)
Horseshoe (31%)
Pinpoint (32%)
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