Working out the cause. Nail varnish is one of the most common causes. After painting your nails, the varnish will give off tiny amounts of chemical vapour for a while, even when it feels dry. If you rub your eye, the eyelid skin may react. Artificial nails can cause a similar eyelid reaction.
The PCL (posterior cruciate ligament) is the strongest ligament, or band of tissue, in your knee. It stretches across the back of your knee. It connects your shinbone to your thigh bone and keeps your knee stable. A sharp, violent blow to the knee can stretch or tear your PCL. That can make it hard for you to get around.
The MCL is another one of the four ligaments in the knee. The MCL is on the inside of the knee joint. and spans the distance from the end of the femur (thigh bone) to the top of the tibia (shin bone). The MCL resists widening of the inside of the joint, or prevents opening-up of the knee. The MCL is usually injured when the outside of the knee joint is struck, causing the outside of the knee to buckle, and the inside to widen. When the MCL is stretched too far, it may tear. A MCL injury may be an isolated injury, or it may be part of a complex injury to the knee. Other ligaments, most commonly the ACL or the meniscus may be torn along with a MCL injury. MCL injury pain is usually focused directly over the ligament.