3 Ways Genetic Counselors Provide Clarity on Eye Disease – Sildenafil
Genetic Origins of Cataract
Cone dystrophy is a general term used to describe a group of rare eye disorders that affect the cone cells of the retina. Cone dystrophy can variably cause a variety of symptoms including decreased visual clarity (acuity) when looking straight ahead (central vision), a reduced ability to see colors and an increased sensitivity to light (photophobia). There are several different forms of cone dystrophy. The age of onset, progression and severity of cone dystrophy can vary greatly from one person to another, even among individuals with the same type of cone dystrophy. Some forms of cone dystrophy are inherited; other forms appear to occur spontaneously for no apparent reason (sporadically).
What is the cornea?
The cornea is the clear, protective outer layer of the eye. The cornea is also capable of filtering out some amounts of the sun’s ultraviolet light.
The cornea also plays a key role in vision. As light enters the eye, it is refracted, or bent, by the outside shape of the cornea. The curvature of this outer layer helps determine how well your eye can focus on objects close up and far away. If the cornea becomes damaged through disease, infection, or injury, the resulting scars or discoloration can interfere with vision by blocking or distorting light as it enters the eye.
At present, genetic testing for any ophthalmic disease is warranted only if it will impact treatment or surveillance, according to the Academy’s guidelines on genetic testing.For glaucoma, this typically means patients with juvenile-onset open-angle glaucoma (JOAG) or congenital glaucoma.
Testing also may be warranted based on a patient’s family history. “We saw a man whose clinical features differed somewhat from the classic presentation for Axenfeld-Rieger syndrome. Also, he has children. For both reasons, we used testing to confirm whether he had primary congenital glaucoma or Axenfeld-Rieger syndrome. With Axenfeld-Rieger syndrome, his children’s risk would be nearly 50%, but for primary congenital glaucoma, their risk would be much lower,” said Wallace L. Alward, MD, at the University of Iowa.
There are 3 main layers of the cornea:
Epithelium: The most superficial layer of the cornea, the epithelium stops outside matter from entering the eye.
Stroma: The stroma is the thickest layer of the cornea and is found behind the epithelium. It’s made up mostly of water and proteins that give it an elastic but solid form.
Endothelium: The endothelium is a single layer of cells located between the stroma and the aqueous humor, the clear fluid found in the front and rear chambers of the eye. Without this specialized function, the stroma could become waterlogged and hazy and opaque in appearance, also reducing vision.