In this episode of Interventional Mindset, Preeya K. Gupta, MD is joined by Vance Thompson, MD; and Justin Schweitzer, OD, to discuss the vital role of osmolarity testing in the pre-operative evaluation of patients undergoing cataract surgery.
Dr. Thompson is the founder and director of refractive surgery at Vance Thompson Vision. He also serves as a professor of ophthalmology at the Sanford School of Medicine at the University of South Dakota. Dr. Schweitzer is an optometrist at Vance Thompson Vision and the Optometric Externship Director at Vance Thompson Vision.
“So many dry eye patients are just used to putting up with it. They just live with it; and so when it comes time for surgery, we're now getting ready to make that eye drier.”
The importance of tear film health
The tear film functions like a "tear lens" that is much more effective than a surgical implant. As a result, an unhealthy tear film can lead to a 20/20 unhappy patient.
Osmolarity testing is a highly sensitive and specific method for detecting dry eye disease, even in patients without symptoms. Having dry eye before surgery can compromise the accuracy of measurements like biometry and keratometry, hinder post-surgery healing, and reduce overall image quality.1,2
“We both know how much dry eye can affect our pre-op measurements, and we want the best outcomes. And we also know dry eye can affect healing.”
Identifying dry eye disease
Patients, including contact lens wearers, often show no symptoms even with significant dry eye disease.1 Therefore, relying solely on symptoms or corneal staining—which is only present in advanced stages—is inadequate.
Dr. Gupta points out that while comprehensive eye exams include vital signs such as visual acuity and intraocular pressure (IOP), doctors don’t have any dry-eye-specific tests. Osmolarity testing provides a reliable, objective "ocular vital sign" for accurate dry eye diagnosis, even in patients without staining.
“I think testing for hyperosmolarity is kind of the start of us getting more of those diagnostics that are meaningful and don't require us as clinicians to wait until we see corneal staining.”
Pre-surgical screening protocols should also incorporate questionnaires such as OSDI or SPEED to identify symptomatic patients,1 with testing conducted on all patients before any drops or other assessments to ensure accuracy.
Considering ocular surface health in surgical decision-making
For standard refractive surgeries, such as with monofocal implants, mild dry eye can often be managed alongside the procedure. However, for premium implants, such as multifocal or EDOF, or for procedures such as LASIK, Dr. Thompson states it's best to delay surgery until the tear film stabilizes (preferably below 300 mOsm/L). This approach ensures greater accuracy and reduces the likelihood of needing additional enhancements.
“The majority of people I see with dry eyes don't stain. That's why osmolarity is so important,” explained Dr. Thompson. “I want to know if that tear film is concentrated. Then I have a decision to make: Am I going to treat it in unison with surgery, or am I going to treat for a little while and delay surgery?”
Patient education and management
Detecting dry eye before surgery enables meaningful discussions about surgical boundaries and helps prevent patients from thinking the procedure caused their dry eye. Recent advances in immunomodulators and other dry eye therapies allow clinicians to improve the ocular surface efficiently, often within 2 to 4 weeks, reducing the need for prolonged treatment pauses compared to a decade ago.
Since dry eye is a chronic condition, effective communication with co-managing physicians is crucial to ensure smooth care transitions, as patients will need ongoing ocular surface management well beyond the surgery.
Key takeaways
- Tear film osmolarity testing identifies dry eye disease with roughly 85% sensitivity and specificity, even in asymptomatic patients.
- Nearly half of cataract surgery candidates with abnormal osmolarity, MMP-9, and corneal staining report no symptoms, making questionnaires alone insufficient for screening.
- Elevated osmolarity correlates with less accurate measurements, poorer healing, and reduced image quality, particularly for premium IOL candidates.
- Surgeons should treat or delay surgery for hyperosmolar states and communicate findings to referring doctors for ongoing management.
- Modern dry eye treatments can normalize osmolarity within 2 to 4 weeks, reducing the burden of delaying surgery compared to a decade ago.
