By Jule Ann Lieberman, CLVT & Team Leader
In the spring edition of The PCB Advocate, I covered some of the most common congenital eye disorders. In this article, we will explore a few more. The following eye disorders have one theme in common: each disorder can be caused by multiple gene locations and medical science has not begun exploration of gene replacement therapies. I will include current medical treatments for each disorder.
The cornea is the front outermost part of the eye. This thin crystal-clear surface is the first region responsible for vision. Several injuries can result in permanent vision loss. However, the focus in this article is on conditions that have been inherited.
Fuchs’ endothelial dystrophy (FED) is a progressive degeneration of the inner lining of the cornea which is responsible for maintaining proper balance of fluid in the tissues of the cornea. One of the suspect chromosomes that cause this breakdown of the lining is COL8A2. However, several others can also play a role. FED is frequently diagnosed in adults between 50 and 60 years of age. Symptoms often begin with blurriness in the beginning of the day, which can improve throughout the day, a high sensitivity to bright light, appearance of halos, and difficulty seeing at night or in dim lighting. The fluid buildup causes a swelling of the cornea, which, in severe cases, can be painful. This can cause distortion and general blurriness or clouded vision.
Treatments for FED begin with topical eye drops to reduce the fluid buildup and, in advanced cases, a patient may receive corneal transplants. The surgical option has its risks that can include infection and rejection of the donated cornea. Post-operative care includes use of steroids which can also pose a risk for further complications in some patients.
Congenital Cataracts occur in newborns, although there is a possible link in adult cataract development in an inheritance pattern in families. In newborn congenital cataracts, the lens which is responsible for accommodating different focal distances has become cloudy. Several factors can play a role in fetal development of a cataract and several chromosomes and genes can lead to this cloudy lens. The cataract can often be detected early by parents and physicians because the eyes of the newborn tend to have a cloudy appearance. Many studies have determined that surgical removal of the lens has a dramatic effect on the development of vision in newborns. Surgery can include an implant or the use of corrective contacts or eyeglasses as the child ages. The optimum time to perform the cataract surgery appears to be between 4 and 6 weeks of age. Risk factors include infection (as with any surgery) and a higher risk of developing glaucoma.
Early onset Glaucoma has also been shown to have a relationship in an inheritance pattern. Persons under the age of 40 with primary open-angle glaucoma are highly likely to have a genetic component. According to the National Institute on Health (NIH), “MYOC gene mutations are responsible for about 10 percent to 33 percent of people suffering from juvenile open-angle glaucoma.” There has been a new study from Flinders University, in Australia, which has identified 107 genes that are responsible for the development of glaucoma. Early genetic identification of those at higher risk of developing glaucoma can have vision loss prevented by early interventions and monitoring prior to experiencing symptoms and increased inner ocular pressure.
Glaucoma is a series of conditions that can lead to vision loss. One common factor in most cases is a buildup of pressure in the eye due to a failure of the regulation of fluids by the eye’s trabecular meshwork that is responsible for the shape of the eye and release of inner ocular fluid pressure. Symptoms can begin with excessive tears, an abnormal high degree of light sensitivity, and eyes that have a bulging appearance. As Glaucoma continues, there is a reduction of the side or peripheral vision, which can lead to mobility challenges and, ultimately, to permanent damage to the optic nerve and total blindness.
Treatments begin with eye drops to lower the Inner ocular pressure and can ultimately involve surgical interventions to allow the trabecular meshwork to drain the fluid. In most advanced cases, an implanted duct is required.
It is the hope of the Vision Loss Resource Team that readers of this and the previous article can gain a better understanding of the various conditions that can lead to vision loss. Each of the conditions described can benefit from use of optical and vision devices to maximize remaining functional vision. Contact the PCB Office or TechOWL (800-204-7428) to explore tools that support your independence.