A 32-YEAR-OLD CAME TO ME having already been refit multiple times by another provider for lenses that “felt like something was in them.” She said the provider had made adjustments and described being “forced” into a daily disposable. Both seem like reasonable provider responses to a complaint that sounds like dryness, but now she was in my chair because neither helped.
But the problem wasn’t dryness. After further investigation, it was revealed that blinking made it worse, and it only affected the right eye. A nasal pinguecula was holding the lens edge off the conjunctiva, and her upper lid caught that edge on every blink. No lens material or refit was ever going to fix that. The diagnosis took 10 seconds.
Lens awareness is a single symptom that could be caused by at least 3 mechanisms: a mechanical interaction between lens and lid, a failing lens surface, or an ocular surface problem the lens is exposing. Each requires a different response, and only 1 of them is solved by a new lens design. When we reach for the diagnostic set before localizing the mechanism, our guessing extends the patient’s chair time and diminishes our own inventory.
Timing: Is the discomfort present from the moment of application, or does it build over the day? Immediate and constant complaints point toward a mechanical cause. Gradual increases in discomfort point to the surface. Is it dehydration, deposits, wetting failure, or a tear film that cannot keep up? Remember that a tight lens is comfortable early and symptomatic late, so the best time to evaluate that fit is at the end of the day.
Asymmetry: Is the problem occurring in 1 eye or both? This is the highest-yield question in the set and the one most often skipped. Unilateral lens awareness is rarely a lens material or care system problem. Look instead for a lens defect, a deposit, a conjunctival elevation holding the lens edge off the eye, an asymmetric fit, a corneal irregularity, or 1 lid behaving differently from its fellow. Bilateral symptoms are usually related to material, replacement schedule, solutions, environment, or the ocular surface itself.
Blink: Does blinking make it better or worse? If blinking brings relief, the blink is resurfacing the lens, and the problem is the tear film. If discomfort occurs during blinking, it likely means a lid is dragging across an edge, a deposit, or an area of standoff.
Stop: What happens upon lens removal? Instant relief often means the lens is the problem. Contact lens discomfort is defined in part by its resolution once the lens comes out. If the eye still feels raw 20 minutes later, the lens is revealing surface disease rather than creating it. Putting lissamine green on the lid margins before you put another lens on that eye can help with diagnosis.
It should be acknowledged that some of these mechanisms coexist. Poor surface wetting raises friction, which in turn produces a genuinely mechanical symptom. TABS (timing, asymmetry, blink, stop) is not a decision tree that ends the workup. It tells you where to point the slit lamp first, which is usually enough.
These 4 questions should be answered during pretesting performed by a trained paraoptometric and documented before the practitioner enters the room. The information gained can be used to identify the underlying mechanism and narrow the scope of the exam. This approach may make the difference between a focused visit and a second, unnecessary refit.
