Protection against corneal hyperosmolarity with soft-contact-lens wear

Hyperosmotic tear stimulates human corneal nerve endings, activates ocular immune response, and elicits dry-eye symptoms. A soft contact lens (SCL) covers the cornea preventing it from experiencing direct tear evaporation and the resulting blink-periodic salinity increases. For the cornea to experience hyperosmolarity due to tear evaporation, salt must transport across the SCL to the post-lens tear film (PoLTF) bathing the cornea. Consequently, limited salt transport across a SCL potentially protects the ocular surface from hyperosmotic tear. In addition, despite lens-wear discomfort sharing common sensations to dry eye, no correlation is available between measured tear hyperosmolarity and SCL-wear discomfort. Lack of documentation is likely because clinical measurements of tear osmolarity during lens wear do not interrogate the tear osmolarity of the PoLTF that actually overlays the cornea. Rather, tear osmolarity is clinically measured in the tear meniscus. For the first time, we mathematically quantify tear osmolarity in the PoLTF and show that it differs significantly from the clinically measured tear-meniscus osmolarity. We show further that aqueous-deficient dry eye and evaporative dry eye both exacerbate the hyperosmolarity of the PoLTF. Nevertheless, depending on lens salt-transport properties (i.e., diffusivity, partition coefficient, and thickness), a SCL can indeed protect against corneal hyperosmolarity by reducing PoLTF salinity to below that of the ocular surface during no-lens wear. Importantly, PoLTF osmolarity for dry-eye patients can be reduced to that of normal eyes with no-lens wear provided that the lens exhibits a low lens-salt diffusivity. Infrequent blinking increases PoLTF osmolarity consistent with lens-wear discomfort. Judicious design of SCL material salt-transport properties can ameliorate corneal hyperosmolarity. Our results confirm the importance of PoLTF osmolarity during SCL wear and indicate a possible relation between PoLTF osmolarity and contact-lens discomfort.     

Topical glaucoma medications – Clinical implications for the ocular surface

Glaucoma is a leading cause of irreversible blindness. The use of topical eye drops to reduce intraocular pressure remains the mainstay treatment. These eye drops frequently contain preservatives designed to ensure sterility of the compound. A growing number of clinical and experimental studies report the detrimental effects of not only these preservatives but also the active pharmaceutical compounds on the ocular surface, with resultant tear film instability and dry eye disease. Herein, we critically appraise the published literature exploring the effects of preservatives and pharmaceutical compounds on the ocular surface.     

术前眼位注视训练对老年白内障超声乳化摘除术患者术中眼位及术后视力恢复的影响

目的探讨术前眼位注视训练对老年白内障超声乳化摘除术患者术中眼位及术后视力恢复的影响。方法选取2018年9月-2019年9月我院收治的105例老年白内障超声乳化摘除术患者为研究对象,按随机数字表法将其分为对照组52例和试验组53例。对照组给予常规围术期管理。观察组在对照组的基础上予以术前眼位注视训练。观察两组术中眼位情况,术后视力恢复情况及术后并发症发生率。结果试验组术中调整眼位次数>3次和眼球旋转偏移率均低于对照组(P<0.05);试验组术后视力恢复至0.5以上比例为60.38%,高于对照组的40.38%(P<0.05);试验组术后并发症发生率为15.09%,低于对照组的32.69%(P<0.05)。结论老年白内障超声乳化摘除术患者术前进行眼位注视训练,通过降低术中调整眼位次数和眼球旋转偏移率,降低术后并发症发生率,促进患者术后视力恢复。     

A rare case of a periorbital respiratory (choristomatous) cyst

Respiratory cysts are benign lesions lined by normal respiratory epithelium. There are few reported cases localized to the orbit, while those of the eyelid are exceedingly rare. Respiratory cysts usually arise either from a non‐hereditary congenital malformation, where they are distinguished as choristomatous, or from trauma. Here, we report a case of a 53‐year‐old man who presented with a large right lower eyelid cyst that was histopathologically diagnosed as a respiratory cyst.     

眼表铁过载小鼠干眼模型的构建和机制研究

目的：通过给小鼠腹腔注射右旋糖酐铁，建立小鼠铁过载干眼模型并初步探索其可能的机制。

方法：将40只雄性C57BL/6小鼠(取右眼为实验眼)用随机数字表法将小鼠分为4组：对照组10只，每次腹腔注射生理盐水0.2mL； 低剂量组、中剂量组、高剂量组各10只为模型组，每次分别腹腔注射浓度为12.5、25、50mg/mL的右旋糖酐铁溶液0.2mL。每3d注射1次，共注射28d。注药后第7、14、28d观察各组小鼠眼表炎症指数、角膜荧光素染色、泪膜破裂时间(BUT)及泪液分泌量(SⅠt)，评估干眼及眼表炎症程度。28d后处死小鼠，取角膜、结膜及泪腺组织，进行HE染色、普鲁士蓝染色以及组织铁检测，评估小鼠炎症反应及铁过载情况； 采用酶联免疫吸附试验(ELISA)检测炎症因子白细胞介素-1β(IL-1β)、肿瘤坏死因子-α(TNF-α)、基质金属蛋白酶-9(MMP-9)的表达情况。

结果：与对照组相比，模型组小鼠出现一系列干眼症状，小鼠眼表炎症指数增高，角膜荧光素染色评分增加，BUT缩短，泪液分泌量减少(均P<0.05)； 模型组小鼠角膜、结膜及泪腺组织均受到不同程度的损伤，各组织眼表铁沉积情况较对照组加重，组织铁含量明显增加(均P<0.01)； 模型组小鼠角膜、结膜及泪腺组织中炎症因子(IL-1β、TNF-α、MMP-9)的含量均高于对照组(均P<0.01)，随着右旋糖酐铁注药时间及浓度增加，小鼠干眼及眼表炎症程度逐渐加重。

结论：腹腔注射右旋糖酐铁可成功建立小鼠铁过载干眼模型，其机制可能与铁过载加重眼表炎症反应有关。