Introduction
Contact lens discomfort (CLD) is defined by TFOS (Tear Film and Ocular Surface Society) as, “a condition characterized by episodic or persistent adverse ocular sensations related to lens wear, either with or without visual disturbance, resulting from reduced compatibility between the contact lens and the ocular environment, which can lead to decreased wearing time and discontinuation of contact lens wear”. Globally, up to 50% of wearers report CLD and 12 – 27% permanently drop out of lens wear despite modern materials.1,2 Discomfort and dryness dominate dropout motives, each cited by ~25% of discontinuing wearers.1 CLD shares the same vicious cycle of tear-film instability, hyperosmolarity and inflammation that drives dry eye disease (DED), and contact lens wear is now recognized as a consistent risk factor for DED.3
Tear Film Disturbance Induced by Contact Lens Wear
Contact lens wear disrupts normal tear film homeostasis by splitting it into two compartments—the pre-lens and post-lens tear films. This division limits tear exchange, especially with soft lenses, reducing clearance of metabolic byproducts, inflammatory mediators, and debris, ultimately compromising ocular surface health and comfort.17 Simultaneously, contact lenses disrupt the continuous lipid layer, creating discontinuous lipid coverage that leads to dramatically increased tear evaporation rates, faster breakup times, and localized dry spots, particularly with high water content lenses that dehydrate on the eye.17,18
The physical presence of the lens creates mechanical shearing forces during blinking that disrupt normal mucin distribution, causing viscous mucin to aggregate into spherical deposits (mucin balls) in the post-lens space.19,20 As the pre-lens tear film evaporates more rapidly, osmolarity increases in both compartments, triggering inflammatory cascades at the corneal epithelium and compromising protein stability and enzymatic function. Over time, protein and lipid deposits accumulate on the lens surface, transforming the originally wettable surface into non-wetting zones where the lubricating tear film is absent, resulting in increased friction and accelerated tear breakup. These disruptions worsen with prolonged wear duration and extended wear over years, as the tear film appears unable to fully compensate for the chronic disruption imposed by contact lens wear, ultimately manifesting as contact lens-associated dry eye characterized by reduced comfort, fluctuating vision, and potential corneal epithelial damage.
In summary, contact lens wear disrupts tear film and ocular surface homeostasis by dividing the tear film into pre- and post-lens layers, reducing stability and meniscus volume, altering cell and nerve function, increasing friction, and driving biochemical and inflammatory changes—ultimately compromising ocular health and increasing dry eye risk.11
With that said, there are various strategies that practitioners can employ to keep their patients happily wearing contact lenses for decades.
