Rose Geoffrey E
Moorfields Eye Hospital, London, UK.
Dev Ophthalmol. 2008;41:127-137. doi: 10.1159/000131085.
The dry-eyed patient has both inadequate surface wetting, and a severe inability to clear the ocular surface of extrinsic debris, lid-margin bacteria (and their toxins), and the intrinsic inflammatory mediators secreted from the inflamed conjunctival surface. Tear evaporation compounds the problem of impaired production, this leading to significant concentration of inflammatory mediators on the abnormal ocular surface - this concentration being even greater where tear drainage is impaired. Nasolacrimal duct obstruction is, moreover, associated with a backwash of toxic debris from the lacrimal sac and, in the patient with dry eye, this backwash exacerbates an already compromised ocular surface. Surgery to re-establish tear drainage and eliminate the reservoir within the lacrimal sac may, therefore, improve the ocular status of patients with dry eye: many patients will benefit from external dacryocystorhinostomy, this being combined with retrograde canaliculostomy where there is proximal canalicular blockage. Secondary placement of a canalicular bypass tube may be required where these procedures have failed and tear drainage is needed. Where there is no risk of ocular surface toxicity due to complete stasis of the tear lake, the canaliculi can be ablated with thermal coagulation or canalicular excision. Rarely required as a primary procedure, dacryocystectomy may be used where dacryocystitis occurs in the presence of long-established canalicular occlusion.
干眼患者不仅眼表湿润不足，而且严重无法清除眼表的外部碎屑、睑缘细菌（及其毒素）以及结膜炎症表面分泌的内源性炎症介质。泪液蒸发使泪液分泌受损的问题更加严重，这导致炎症介质在异常眼表上显著浓缩——在泪液引流受损的情况下，这种浓缩更为明显。此外，鼻泪管阻塞与泪囊有毒碎屑的反流有关，对于干眼患者，这种反流会使本已受损的眼表情况恶化。因此，重建泪液引流并消除泪囊内潴留物的手术可能会改善干眼患者的眼部状况：许多患者将受益于外路泪囊鼻腔吻合术，若存在泪小管近端阻塞，则可联合逆行泪小管造口术。如果这些手术失败且需要泪液引流，可能需要二次放置泪小管旁路管。在泪湖完全停滞不会导致眼表毒性风险的情况下，可通过热凝或泪小管切除术切除泪小管。泪囊切除术很少作为主要手术使用，在长期存在泪小管阻塞并发生泪囊炎的情况下可采用。
