4.5 Iatrogenic Causes |
71 |
a |
b |
c |
d |
Fig. 4.3 (a) Inflammatory sequelae of lichen planus, identifying complete destruction of the epithelium (chevrons), dense subepithelial fibrotic changes (short arrow), and lymphocytic infiltrate (long arrow) (hematoxylin and eosin, original magnification ×20); (b) Stevens–Johnson syndrome presenting with severe pseudomembranous conjunctivitis; (c) advanced bilateral ocular cicatricial pemphigoid demonstrating bilateral medial ankyloblepharon and punctal occlusion; (d) magnified view of left eye showing severe synblepharon and medial ankyloblepharon completely obstructing punctum (arrow shows probable location)
most cases, these patients will require DCR and retrograde canaliculostomy, with occasional later placement of a glass bypass tube.
requiring surgery, with this occurring at the level of the common canaliculus in one case and at both the canaliculi and nasolacrimal duct in another patient [2].
4.4.3Drug Eruptions (Stevens–Johnson Syndrome)
Stevens–Johnson syndrome (SJS), the bullous form of erythema multiforme, is an acute and self-limiting inflammatory disorder of the skin and mucous membranes. Severe, and often hemorrhagic, conjunctivitis with pseudomembrane formation may occur in over half of patients (Fig. 4.3b), with the resultant subepithelial fibrosis leading to conjunctival symblepharon, cicatricial entropion, loss of limbal stem cells, and obliteration of the lacrimal gland ductules. These changes reduce production of tear-film mucin and aqueous tears, making any punctal or canalicular occlusion less troublesome; indeed, in one study, objective evidence for lacrimal outflow disease was noted in most cases, although none required surgery, presumably due to the simultaneous reduction in the quantity of tear film [37]. Other authors have reported significant lacrimal outflow obstruction
4.5Iatrogenic Causes
Canalicular or pericanalicular inflammation may arise from a number of iatrogenic causes, with these typically due to systemic medications or local radiotherapy.
4.5.1Systemic Drugs
4.5.1.15-Fluorouracil (5-FU)
A potent inhibitor of DNA synthesis, 5-FU is widely used in the management of systemic malignancy, with rapidly proliferating tissues, including normal epithelial surfaces, most affected. Healthy canalicular epithelium may be affected in about 6% of patients, with this leading to punctal narrowing and focal or diffuse canalicular stenosis; over a quarter of these individuals require DCR with placement of a bypass tube [14].