Causes And Countermeasures Of Corneal Edema Before Femtosecond Corneal Refractive Surgery

To reduce the incidence of complications in femtosecond corneal refractive surgery caused by corneal edema by preoperative observation and evaluation of the degree of corneal edema, analysis of the causes of edema, and discussion of preventive measures.

 1120 people (2236 eyes) underwent femtosecond assisted corneal refractive surgery. Patients with corneal cloudiness, macular or leukoplakia were excluded before the surgery. After the preoperative preparation (conjunctival sac washing, topical anesthesia), slit lamp and PENTACAM examinations were performed. According to the corneal epithelial edema, they were divided into three groups: mild, moderate and severe;

The patients with mild and moderate edema completed the operation as planned, and the patients with severe edema were rescheduled; For patients with moderate and severe corneal edema, complete the analysis of relevant factors (such as wearing contact lenses, inflammation, cold, disinfectant stimulation, improper conjunctival sac washing operation, long-term exposure during operation, etc.). At the same time, the occurrence of dark spots in patients with mild and moderate edema during femtosecond laser corneal scanning was statistically analyzed.

(1) The patients who completed the preoperative preparation (preoperative surface anesthetic, conjunctival sac washing) had different degrees of epithelial edema, which were mild (81%), moderate (19%), and heavy (0.001%); (2) The importance of the relevant factors from high to low is: wearing contact lenses, inflammation, conjunctival sac flushing, disinfectant stimulation; (3) In patients with mild corneal edema, there was no scanning black spot during the operation, while in patients with moderate edema, there were 4 cases (0.004%) with small black spots in the edema area. All patients continued to complete the operation, and 1 case had obvious black spots in the central area. The operation was terminated after scanning.

Conclusion: Wearing contact lenses, inflammation, conjunctival sac flushing, and disinfectant stimulation may cause corneal edema in different degrees before operation. The preoperative corneal edema should be evaluated and graded, and preventive measures should be taken to reduce the incidence of complications in femtosecond corneal refractive surgery caused by corneal edema and improve the operation safety.