Tear Fluid for the Detection of Tumor-associated Extracellular Vesicles in Glioblastoma Patients

This clinical trial tests the impact of tear fluid in detecting tumor-associated extracellular vesicles (TEVs) in patients with glioblastoma. Brain tumors release small particles, called TEVs, that may provide information about the tumor, including how it responds to treatment. These particles can be found in cerebrospinal fluid (CSF), which is the fluid that surrounds the brain and spinal cord. Collecting CSF can be difficult and expensive, especially if samples are needed frequently to track these particles over time. Tear fluid is easier to collect than spinal fluid. If tears are found to contain similar tumor-related particles, changes in the tumor may be tracked by studying the particles found in tear fluid.

Inclusion Criteria: * Adults (age ≥ 18) * Male and female * All racial and ethnic groups * Pathologically-proven diagnosis of GBM or healthy volunteers * For GBM patients, presence of a previously placed Rickham reservoir or shunt * Able to provide informed consent (or via legal representative) * Willing to undergo Schirmer strip procedure Exclusion Criteria: * Active ocular infection or inflammation * Recent ocular surgery (within 3 months) * Chronic dry eyes * Known allergy or hypersensitivity to topical anesthetics * Cognitive impairment * Pregnancy * Any condition that, in the opinion of the investigator, would interfere with the participant's ability to comply with study procedures or place the participant at undue risk