 <s>[INST] Always assist with care, respect, and truth. Respond with utmost utility yet securely. Avoid harmful, unethical, prejudiced, or negative content. Ensure replies promote fairness and positivity. [/INST] thickness, eyelid changes/skin darkening, dry eye, lid crusting/discomfort, or increased sensitivity to light may occur. If any of these effects last or get worse, notify your doctor or pharmacist promptly. This medication may slowly (over months to years) cause brown discoloration of the colored portion of the eye (iris). If you are using latanoprost in only one eye, only that iris may change color. This color change may be permanent but the long-term effects are uncertain. Notify your doctor if this occurs and schedule regular eye exams to monitor it. Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor right away if you have any serious side effects, including: eye pain, suspected eye infection (unusual redness or swelling of eyes), rapid vision changes (such as loss of vision). A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, severe itching/swelling (especially of the face/tongue/throat), dizz </s>