This question came up because my son’s babysitter is fostering a blind dog – an adorable little black poodle with milky white eyes named Rosie.
My son and his babysitter’s two children love her and spoil her and carry her around, and they describe her as having “moon eyes” because they sort of look like full moons. The Peppermint Pig Animal Rescue was going to get her eyes operated on to remove the cataracts, but it turns out she also has detached retinas. So the surgery wouldn’t really change anything for her.
We were talking about the dog, and the news, and my son asked “what are cataracts?” Because we’d used the word and he didn’t know it.
“It’s what makes Rosie’s eyes white,” my wife replied.
“But what are they?” he replied.
“It’s…” My wife thought for a second. ‘It’s like a film on her eyes, that she can’t see through.”
“But why are they called that?” my son persisted.
So. What are cataracts?
I’ll be honest, here. I don’t actually know. My wife’s explanation seemed as good as any, and I think I always sort of assumed that they were something like scar tissue. But, like with so many other things, I’ve never really stopped to ask what they were or what causes them. So, since my son asked, it’s time to change that.
Merriam-Webster, my go to for dictionaries thanks to a handy app, gives two definitions for “cataract“:
- [Middle English, from Medieval French or Medieval Latin; Medieval French catharacte, from Medieval Latin cataracta, from Latin, portcullis] : a clouding of the lens of the eye or of its surrounding transparent membrane that obstructs the passage of light
- a obsolete : waterspout
b : waterfall; especially : a large one over a precipice
c : steep rapids in a river the cataracts of the Nile
d : downpour, flood cataracts of rain cataracts of information
I’m guessing that the medical term is used explicitly because of the “portcullis” meaning in Latin, since cataracts more or less block light from entering the eye. The Online Etymology Dictionary seems to agree, so that makes me feel better.
The medical condition
Multiple online sources (the Mayo Clinic and the American Academy of Ophthalmology to name just two) agree with the Merriam-Webster definition. Cataracts are a clouding of the lens of the eye. This can result in blurry vision, seeing double, light sensitivity, having trouble seeing well at night, needing more light when reading, seeing “halos” around lights, and seeing bright colors as faded or yellowed. They are the most common form of vision loss in people over the age of 40, and the single most common cause of blindness in the world (in the US alone, more than 22 million people have cataracts).
Aging is the most common cause of cataracts, because the proteins in the lens of your eye will denature over time. This is not a good thing, because your lens is made of living cells and denatured proteins disrupt the cells and can even kill them. Diabetes and high blood pressure can accelerate the process, as can ultraviolet light (UVB, specifically) and other radiation and blunt trauma to the eye. There is a genetic component to the development of cataracts as well, particularly if someone develops them in childhood or as young adults. These aren’t the only causes, of course. Just the most common.
The most common forms of cataracts are subcapsular, nuclear, and cortical. Subcapsular cataracts start at the back of the lens, and are most common in diabetics and people taking medical steroids. Nuclear cataracts start in the center of the lens, and are most commonly associated with aging. Cortical cataracts start at the edge of the lens and work inwards ina “spoke-like fashion”. There are also congenital cataracts, which you are born with or develop during childhood – usually due to your genes or some form of infection or trauma.
Ultimately, the only treatment for cataracts is to remove the existing lens and replace it with an artificial lens called an intraocular lens that matches the prescription (if any) that you need for your glasses. The intraocular lenses come in a wide variety of different types, and if you need one you should consult with your ophthalmologist to see which ones make the most sense for you.
Surgery is generally considered a last resort, though. As long as the cataract symptoms aren’t bothering you, and the problems with your vision can be corrected with glasses, there generally no need to undergo surgery. Cataract surgery is considered pretty routine, but the only really risk-free surgery is one that you don’t have.
Hang on, hang on. This is all about people. Didn’t this start with a dog?
Yep. But cataracts aren’t limited to humans. It’s a condition caused by disruption and damage to the lens of the eye, so any animal with an eye with lenses can develop cataracts. There’s a lot of information on the internet about dog cataracts, and mentions of cats. One veterinarian stated that they are “the most common cause of blindness in dogs, and can also affect people or any species of animal”. Like humans, animal cataracts can develop from age, diabetes, trauma, genetics, or something called Progressive Retinal Atrophy – the name for a cluster of generic disorders that cause the retina to degenerate. Animal cataracts can be treated in the same way as human cataracts. Progressive Retinal Atrophy has no treatment, though.
Impaired vision and even blindness aren’t a death sentence for a house pet, though. Rosie gets around just fine, as long as you don’t move her food and water dishes and rearrange the furniture a whole lot. So if you live in the Cincinnati area and want to adopt an adorable little blind dog (or another animal), contact the Peppermint Pig Animal Rescue. They’ve got a lot of animals looking for a loving new home.