he purpose of this research is to better understand giant cell arteritis (GCA), especially the eye problems caused by GCA that some people experience. Although ophthalmologists know how to diagnose and treat this potentially blinding disease, little has happened in the field to improve our ability to diagnose and treat GCA, or to minimize the complications of treatment. This study will include GCA patients who are scheduled to undergo superficial temporal artery biopsy (STAB) as part of their standard care.   We will obtain blood and biopsy samples in order to further our understanding of GCA and learn about the gene that causes GCA.  We will also collect information from participants' medical records. These efforts may lead to a better understanding of why the condition develops (and eventually lead to improved treatment or management).  The research may eventually help researchers develop ways to predict who is likely to be affected by GCA and to what degree.