Although many eye diseases generally manifest themselves later in a person"s life, there are some which can affect people of any age, with keratoconus one particularly damaging condition that can affect anyone.
It is a progressive eye disease that involves the usually-round cornea thinning and beginning to bulge into a cone-like shape, which deflects light as it enters the eye on its way to the light-sensitive retina, resulting in distorted vision.
The condition can occur in either one or both eyes and most often starts to develop during a person"s late teens or early 20s.
One individual who knows the effects of the condition and how much suffering it can cause is Kaley Jones.
She recently told NPR.org how she came to realise she was developing the disease and the steps she took to try and remedy the situation.
Kaley was only 17 when keratoconus began to manifest itself, initially while she was in a history lesson and could not read the blackboard or decipher the faces of her classmates.
"It was really scary. It was kind of like looking through plastic wrap. I could see colour, but no real detail," she explained.
Kaley soon learned she had suffered a rupture of the inner layer of her cornea, which is one of the complications associated with keratoconus.
Often, the disease can be difficult to detect because it usually develops slowly, but in some cases, keratoconus proceeds rapidly and, as the cornea becomes more irregular in shape, causes progressive nearsightedness and irregular astigmatism.
These create additional problems such as distorted and blurred vision, along with glare and light sensitivity, all of which Kaley began to suffer from, resulting in her diagnosis.
She told NPR that initially she considered trying to use rigid contact lenses which often help to reshape the cornea, but vision experts were unable to improve her sight through this method.
"We went through 20, 30, 40 pairs of contacts, trial after trial. But because my corneas were so cone shaped, it was kind of like trying to put a plate on a peak. They just kind of wobbled, and didn"t fit," she explained.
The only other option to correct the condition, which was by this point significantly affecting her happiness, was a cornea transplant, even at the tender age of 17.
She explained to the website that she was at first apprehensive, but was soothed after visiting Anthony Aldave, a corneal transplant surgeon at the University of California, Los Angeles" Jules Stein Eye Institute, who was able to carry out the procedure.
For Kaley, she says the results were immediate and she could soon begin to enjoy life again without being hampered by defective vision, all thanks to the organ donor whose corneas were used in the operation.
"I could see shapes, detail, faces; it was insane, just incredible. Someone else"s tragedy resulted in an amazing gift to me. I will definitely be an organ donor. Definitely. It was not even something I ever thought about. But now, I know what it means," she explained.
Dr Aldave explained that 95 per cent of cornea transplants are now successful to the point where they make a major improvement to people"s lives, and Kaley was one such subject who has been able to get on with things the way she did before developing the disease.
She now wears regular Contact lenses during the day but is able to read and drive - two things she really enjoys - without discomfort and is looking forward to a future without defective eyesight.
Dr Aldave told NPR: "In Kaley"s case, my hope is that she can get at least 30 years out of each of these corneas. And, with newer techniques, I may be able to just replace the inside layer of her cornea after that."
by Emily Tait