This audio article is from VisualFieldTest.com.

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Excerpt:

Dry Eye & Glaucoma: Fix the Surface, Fix the TestsPersistent dryness and irritation of the eye surface—often called dry eye disease or ocular surface disease—is very common in people with glaucoma (especially those using eye drops). This surface problem can blur vision, make you blink more, and change the way your eyes see light. That in turn can throw off glaucoma tests. For example, a frustrated, burning eye may cause more false-positive or tracking failures on a visual field test () (), or a rough tear film can cause the OCT scan light to scatter and “miss” part of the nerve fiber layer. In short, dry eye can fake glaucoma progression by making tests look worse even when the nerve fibers haven’t changed. Before declaring your glaucoma is getting worse, doctors must check and optimize the ocular surface. Treating the dryness and lids first will give more reliable test results. In this article we explain why, and give a step-by-step guide to “fixing the surface.” How Ocular Surface Disease Skews Glaucoma TestsVisual Field Tests (Perimetry): If your eyes are irritated or your vision fluctuations, it’s hard to concentrate during a perimetry test (when you press a button for each light you see). Studies have shown that patients with more severe dry eye symptoms tend to have more tracking failures and unreliable field tests (). In one study, giving just one drop of artificial tears before testing noticeably improved visual field quality – lowering false negatives and giving a better average result (). In practice, unresolved dryness can make it seem like your field is worse. OCT Scans: Optical coherence tomography (OCT) uses light to map the retina and nerve layers. A healthy tear film and clear cornea are needed for crisp images. Dry or irregular tears can cause segmentation errors – the software might misidentify layer boundaries when the images are foggy or have debris. (). These errors often underestimate nerve fiber thickness by a few microns (). In other words, an OCT scan taken through a bad tear film can look falsely thin, mimicking glaucoma damage. In fact, a classic study found that about 20–50% of automated OCT RNFL scans had some error, especially when image quality was lower (). (Always ask your doctor if they checked scan quality or redid an OCT if the results looked surprising.)Why It Matters: If dryness causes a test to look worse on one visit (and better the next), the glaucoma doctor might misread this as disease progression. By contrast, if the surface is healthy and stable, any change is more likely real. We want to remove the “fake” changes caused by the surface. Bold and bright perfectly healthy eyes will give much more consistent test results. So treat first, test second. Improving the Ocular Surface: A Step-by-Step RegimenYour eye doctor or optometrist may suggest a stepwise approach to restore a smooth, hydrated surface. Here’s a typical plan:Use Frequent Preservative-Free Artificial Tears: Instill a preservative-free lubricating eye drop several times a day, before testing and in between glaucoma meds. Preservatives in many eye drops (like benzalkonium chloride) can worsen dryness and irritation over time (). Opting for preservative-free formulations (which many pharmacies carry) helps prevent further damage. Artificial tears re-establish a smooth tear film and clear vision. Research shows that even one drop immediately before a field test can improve the result (). In practice, try to keep your tears topped up all day (for example, 4–6 times daily