Post-refractive surgery dry eye is an unwanted yet reoccurring problem for surgeons, according to Dr Cummings. In this article, he discusses the pre-op approach taken in his practice, which leads to a more certain diagnosis and higher patient satisfaction rates.
The TearLab Osmolarity System (TearLab Corp, San Diego, California, USA) is designed for in-practice diagnosis of dry eye. Unlike laboratory-based osmolarity tests, which can require up to 10 µL of tears, the system is able to assess osmolarity using a 50-nanolitre tear sample. It provides an objective measurement in less than a minute.
The key advantage to using osmolarity versus other dry eye diagnostic tests is that it provides a higher degree of sensitivity and specificity, based on a comparison of osmolarity, tearfilm break-up time (TBUT), Schirmer, corneal and conjunctival staining and meibomian gland grading.1 One point that requires some adjustment when using osmolarity is the variability in measurements between one patient's eyes and from visit to visit. However, this variability, in and of itself, is a classic hallmark of dry eye disease and does not exist in a healthy functional lacrimal system.2 In fact, if there is more than an 8 mOsm/L difference between two eyes, even if one eye appears in the normal range (≤308 mOsm/L), then we know that we have to treat the dry eye first before proceeding with surgery.