The utility of normal tear osmolarity results
Rule out dry eye, rule in the real diagnosis
The everyday impact of accuracy
Consider what was achieved by getting the right diagnosis--and what was avoided by not insisting these 50 patients had simple DED.
Treatment was ultimately different than what would have been prescribed for dry eye. If we assumed these patients had DED and treated them for it, they would return unsatisfied with ongoing or worsening symptoms, leading to both patient and physician frustration.
Making the right diagnosis and targeting the treatment regimen to that specific problem on the first visit leads to happier patients, more referrals, and less chair time.
Normal tear osmolarity flags me to look for something else. By trusting the normal osmolarity result and adjusting my exam accordingly, I save a lot of time by homing in on a potential alternative diagnosis to DED. I get a clearer picture of where the real pathology might be.
When the alternate diagnosis is obvious - for example, a large entropion with trichiasis causing foreign body sensation - tear testing is clearly unnecessary. When the symptoms and/or signs are subtle, which is often the case, the diagnostic value of normal or abnormal osmolarity testing increases dramatically.