Ocular surface and refractive surgery

Purpose Dry eye represents nowadays the most common complication after PRK and even more frequent after lasik. Preoperative dry eye constitutes a risk factor for postoperative severe dryness; that it why it appears crucial to detect and treat surface disorder before the surgery. Methods We will remind the list and hierarchy of tests available for the assessment of ocular surface. Unfortunately, values of the defined criteria are variable and there are a lot of variations in the methods. Moreover, the correlation between clinical symptoms and tests results is very poor. The access to tear osmolarity (TearLab©) could be an interesting new biomarker. A study will be presented showing that 44% of patients, candidates to Lasik have an asymptomatic dryness before surgery (mild to moderate stage. Results Related to the principle of these two procedures, the cause of ocular surface deregulation lies on neurotrophic disturbances (secondary to nerves section) and inflammation ( wound healing process). In addition, changes in corneal shape can affect the tear dynamics with an increase in ocular surface dessication. All these phenomenon are systematically observed after photoablation for a transitory period of 1 to 3 months. But, sometimes, they do persist beyond one year (20%), becoming chronic and source of a great discomfort and dissatisfaction (10%). The strategy of treatment will be discussed, in graduating the medications according the growing severity. Conclusion Is there a difference between surface PRK and Lasik ? Hinged flap induced transection of large number of afferent sensory nerve fibers during lamellar cut, that impacts the integrated lacrymal gland OS functional unit. Finally, Lasik is responsible of more dry eye syndrome that PRK, that should be prefered in case of preoperative Ocular surface disorder.