As the name implies, contact lens solution toxicity occurs only in patients who wear contact lenses. This toxicity is very often associated with improper contact lens wear or poor contact lens hygiene. The more common form of contact lens toxicity is caused by contact lens overwear (often sleeping in contact lenses) leading to corneal hypoxia. This will lead to rapid decline in vision associated with ocular pain, redness, and light sensitivity. Chronic hypoxia will cause corneal scarring and vascularization. The second type of contact lens toxicity was classically associated with the preservative thimerosal but can be seen with any contact lens solution. With this type of toxicity, patients will complain of ocular discomfort and foreign body sensation. Patients may notice reduced vision, especially when trying to use their glasses and will typically present with severe pain, light sensitivity, and often reduced vision.