As part of eye care awareness month, I will be writing a few informative pieces on some of the more 'notorious’ eye conditions commonly found in South Africa.
As part of eye care awareness month, I will be writing a few informative pieces on some of the more 'notorious’ eye conditions commonly found in South Africa.
We’ll start off with a condition known as Retinitis Pigmentosa, or RP, as it is more commonly known. An estimated one in 5 000 people are affected by this disease, making it the most common genetic cause of blindness today.
Retinitis Pigmentosa actually refers to a diverse group of hereditary eye disorders that attack the photoreceptor cells of the eye.
In short, we have two types of photoreceptor cells: rods and cones. Rods are mostly used to help us with night vision, while our cones help us to appreciate colour and fine detail.
Although it is unusual for people with RP to become totally blind, as most retain some useful vision well into old age, their sight is still drastically affected.
RP initially affects the rod photoreceptor cells, causing a decrease in night and peripheral vision.
The most common first symptom, however, is difficulty seeing in poor light, especially during dusk or dawn. A person affected by RP would normally struggle to perform relatively simple tasks like walking, orientating themselves and walking down stairs the moment light conditions start changing.
A doughnut-shaped blind spot that extends inwards and outwards starts to appear later on in the disease, progressively getting bigger and bigger. This is commonly referred to as “tunnel vision”.
This makes it especially difficult for people affected by the condition to explain their symptoms to friends and family. Although they can often still read, they might need a guide while walking to orientate themselves properly.
Ultimately RP starts affecting central vision as well, even causing complete blindness in certain cases. The age of onset, rate of progression and eventual visual loss are largely related to the type of genetic inheritance the condition is linked to and the type of RP they are suffering from.
There are basically three ways that the disease can be passed on.
The first, Autosomal dominant inheritance occurs where RP is known to exist in a family, affecting both men and women equally. The chance of the abnormal gene being passed from an affected parent to a child is roughly 50%.
In the second type called Autosomal recessive, there is usually no known history of RP in the family but there’s still a 25% chance that a child can get the disease if both parents are carriers of the gene.
The last type of inheritance, called X-linked, only affects men but women become carriers of the gene and it commonly skips one generation of men before affecting the next.
About 25% of people affected with the disease maintain relatively good vision and are able to read throughout their working lives.
Although there is currently still no definitive cure for RP, numerous studies and clinical trials are underway all over the world. Recently retinal microchip implants have even been used to improve vision in people with advanced RP to some degree.
Other studies are looking towards gene therapy and stem cell research which seems to hold vast potential for future advancement in the search for a cure.
Currently Retina SA (www.retinasa.co.za) also serves as a great source of inspiration to people seeking help or information regarding the condition.
Ultimately, contacting and registering yourself with one of the numerous support groups offering help to people suffering from this (and other similar) conditions, is the best way to get in touch with people that understand what you are going through and who can offer valuable insight into coping with RP.
