Good evening! Hope everyone is well.
I have my first assignment from a reader/ member! She asked about non-genetic causes of macular degeneration.
When I started to research, I thought I was going to fail my first assignment! I found a list of over 50 causes of blindness, and the great majority of them had a genetic basis. According to the Cleveland Clinic, 60% of cases of blindness in infants are genetic. Add such things are glaucoma, basic refraction errors and AMD and a good portion of vision problems are, indeed, genetic. It does appear we are made with some planned obsolescence in the design!
Then I looked again (and yes, Lin gave me a nudge in the right direction), and I realized the reader had asked more specifically about viral or other disease causes. That search yielded much better results.
Here goes…
Retinas can be affected by a wide variety of diseases. There are all sorts of articles on ocular infections. Things such as ocular toxoplasmosis can cause retinal infections particularly in individuals who are immunocompromised. Toxoplasmosis is a parasite frequently found in cats. The endpoint of ocular toxoplasmosis is scarring. Depending upon where on the retina the scarring is located, vision may or may not be compromised.
The Patient (March 12, 2014) article on Inflammatory Retina Diseases went on to mention several other diseases that can cause severe visual impairment. Keeping to parasites, dog and/or cat roundworm can cause ocular toxocariasis. The larvae can migrate to the back of the eye and die. Lovely thought. Apparently dead roundworms in your eye can cause retinal fibrosis (read scarring) and even retinal detachment. Yuck.?
And continuing in that vein, diffuse unilateral subacute neuroretinitis (DUSN) is caused by, not dead larvae, but larvae poop! This disease can cause scotomata (blind spots) and floaters. Depending upon where the larvae poop is, it could potentially affect the macula, but wherever they go, DUSN is sight-threatening. Another yuck.
Moving on to infectious disease, The Patient reviewed the effects of herpes on eyes. Not necessarily talking “social disease” here. Herpes simplex causes cold sores. Varicella zoster is a herpes virus. It causes chickenpox and shingles.
When left untreated in eyes the herpes virus can wreak havoc. It causes scar tissue and once again depending upon where that scarring is, there can be significant vision loss. Also, without treatment herpes in one eye will spread in the other eye in a whopping 65% of cases. Herpes eye infections can also cause retinal detachment and optic nerve damage.
I am starting to think I would rather the parasites. Yuck.
Cytomegalovirus (CMV) is, according to the Wiki people, another member of the herpes family. The CDC reports CMV is in half of all adults over 40. While it generally does not cause problems in its host, CMV can reactivate. In the eyes, CMV can cause hemorrhages and necrosis of the retina. Necrosis is a fancy name for death.
And I haven’t even gotten to the fungi yet! I guess that means I write a follow-up page on this.
Yuck.
Written September 28th, 2018