Congenital fibrosis of the extraocular muscles 1B (CFEOM 1B) is one type of a group of genetic conditions that appear at birth (congenital) and affect the muscles surrounding the eyes. These muscles control eye movement and the position of the eyes (for instance, looking straight ahead). In all forms of CFEOM, the muscles do not develop properly and are not able to control their eye movements properly. Symptoms of CFEOM type 1B include drooping of both eyelids (bilateral ptosis), misaligned eyes where the two eyes do not look in the same direction (strabismus) and a downward gaze (difficulty bring eyes above midline). Because of the weakened muscles and drooping eyelids, people with CFEOM1B typically have a slightly tilted back head or may need to turn their head instead of using their eyes to look to the side.
Treatment often involves surgery to correct the position of the eye and the eyelids. CFEOM1 is the most common of this group of conditions and is divided into two groups 1A and 1B based only on a difference in which gene carries the error that causes CFEOM. In CFEOM1B, the TUBB3 is the involved gene and this form is inherited in an autosomal dominant manner. People typically have two copies of every gene. In a dominant condition, only one copy of the gene causing the condition needs to have an error for the condition to be present, in this case, the TUBB3 gene. An individual with CFEOM1B has a 50% chance of passing the condition on to each of their children. A genetic counselor may be helpful to understand the inheritance of the condition. If your child has been diagnosed with CFEOM1B, talk with your child’s doctor and eye specialists about the most current treatment options.