Lid lag is a condition in which the upper eyelid is unable to follow the rotation of the eye. The condition is usually evident when the eyelid is unable to move at all, or when the movement of the lid is noticeably behind the movement of the eye. This condition is also known as Von Graefe's sign.
In many instances, the individual suffering with lid lag may not be aware of his or her condition. This is because the lag may develop incrementally over time, which minimizes the opportunity for the individual to perceive any difference in what is considered normal eyelid movement. However, the condition can be readily observed by loved ones as well as by a physician.
A qualified physician can determine if lid lag is truly present and also run tests to identify the origin of the condition. In many cases, the lid disorder is associated with an overactive thyroid. Hyperthyroidism associated with lid problems can usually be treated by the administration of medication to compensate for the activity level of the thyroid.
In situations where the overactive thyroid does not respond well to medication, it may be necessary to remove a portion or the entire thyroid in order to deal with the nervousness, anxiety and inability to control various muscle groups in the body, including lid lag. However, this is considered to be a form of treatment that is only employed when other methods have failed to produce results.
Lid lag may also be due to some type of unusual development involving the cranial nerves. In cases of this type, some form of aberrant regeneration of the individual fibers that make up the ocular nerve may be the underlying cause. The aberration in turn causes the ability to elevate and lower the upper eyelid to be impaired or impossible.
A basic lid lag test is easy to conduct. An object such as a pen is held in front of the individual, slightly higher than eye level. As the object is moved downward and the eyes follow the movement, it is simple to observe how the eyelid responds. If the lid does not exhibit any movement in relation to the movement of the eye, or if the lid moves in short jerks, there is an excellent chance that this condition is present.