Supporting people with aniridia and their Families
Just Diagnosed? click here
Supporting people with aniridia and their Families
Just Diagnosed? click here
Foveal/Macula HypoplasiaWhat are the fovea and macula? The macula is a small area on the retina designed for seeing detail, therefore is the area responsable for visual acuity (20/20 etc. vision). It is mostly made up of Cone cells, which are cells which detect coloured light. In the middle of the macula is the foveal pit, this is a dip in the retina which is made up entirely of densely packed cone cells and no blood vessels run through this area. Because of this it is the only area of the eye capable of 20/20 or better vision. In a normal eye, when a doctor looks through a ophthalmoscope, The foveal pit causes a bright reflex What is Fovea/macula hypoplasia? Hypoplasia is a medical term for underdevelopment therefore fovea/macula hypoplasia means underdevelopment of the macula generally or the fovea specificly, there is no clear distinction between the two doctors have their own preference of which term to use. A doctor can tell whether or not a fovea is underdeveloped by looking at it through an ophthalmoscope (this is usually a handheld device which sends a small beam of light into the eye.) - lack a foveal reflex - Absence of yellow macula lutea pigment - There there are blood vessels running through or into this area. How does it affect a person? Depending on the how underdeveloped the macula is, the most significant affect of fovea hypoplasia is reduced visual acuity. - The vision can range from 20/20 to 20/200. - There is no clear correlation between the physical appearance of macula hypoplasia and visual acuity, if a child has fovea/macula hypoplasia the it will be difficult to determine how much vision the child has until they can indicate this themself - Nystagmus, shaking of the eyes Why do people with aniridia have Fovea/macula hypoplasia and how does it affect them? Aniridia is a condition in which the eye is generally underdeveloped and therefore, at the back of the eye the retina and the optic nerve tend to show some degree of underdevelopment. Almost all people with aniridia have fovea hypoplasia to some degree. Because aniridia is condition that occurs in both eyes, both eyes will usually have fovea/macula hypoplasia. However, they may be affected to different degrees. if this is the case the brain may prefer the eye with better vision making this the dominant eye. Because of this the non-dominant eye will become weak. Sometimes to prevent the childs doctor may choose to patch the dominant eye to encourage sight in the weaker eye. People with aniridia tend to have nystagmus and they usually have between 20/100 and 20/200 vision. References Ohio LIONS Eye Research Foundation - dictionary The Royal Victorian Institute for the Blind - Glossary of Terms Oetting, W. S. (1999). Albinism. Curr Opin Pediatr, 11(6), 565-71 |