PHPV: the eye, vision, and how I see
[for other posts in the category, click ‘older posts’ at bottom]
PHPV (Persistent Hyperplastic Primary Vitreous) is a rare, congenital eye disease that begins around the third month in utero. I have it in my left eye (right to you) and have written about it before. In short, the primary vitreous and hyaloid artery of the developing eye do not become clear and recede (they’re persistent), but instead grow even more (hyperplastic), scar, and form a stalk. Sometimes this is in the front of the eye. Sometimes the back. Mine runs from the cornea in the front all the way back to the retina. This, my ophthalmologist calls “classic,” “amazing,” “beautiful,” and “textbook” when describing it to her residents, whom she will pull off lunch break to view because it’s so rare to see such a case. Also rare because the cataracts and calcium deposits that can develop on the cornea often make it impossible to see into the eye. Not so for me. Mine fog up only the right side of my eye, so you can see straight in.
It is oddly comforting to have my deformity so appreciated. And since I’m a huge advocate of real world education, I’m happy to let the apprenticing doctors take a look, painful as it may be.
When I was little, as in the photo above, the deposits gave the eye more of a blue cast, so I appeared to have one brown eye and one blue (no, not like your cat). Now the coloration isn’t as extreme, but the eye is smaller (microphthalmia) and doesn’t track with the right. Other side effects are the retina peeling off a bit and elevated eye pressure (glaucoma). I have both, though both are pretty stable.
I have yet to meet someone with PHPV. There’s a facebook group called “People with Persistent Hyperplastic Vitreous Unite” but it should be called “Parents of Babies & Toddlers with PHPV Support and Discuss.” I’ve chatted online with someone upstate (we’re FB friends now), and a few people here who have read my other posts, but I have never met another person with this disease. And before the internet (most of my life), the only information I got was from my ophthalmologist. There’s only so much one can absorb in a visit.
That’s why I write this. There’s very little info out there, and nothing about what it’s like to have PHPV.
Even so, I’ve known I see differently since I was young. My pediatric ophthalmologist (he was mean. Parents of Small Children with PHPV, please do not send your child to a mean eye doctor. Traumatown) gave me a slew of tests. One was a fly coming off a board, and I was meant to say if it was 3-D or not. It was the 70s, and this was the “Titmus Fly Stereotest.” Oh, I found a picture. What a horror.
I knew there was a correct answer to the question and I was pretty sure it was not what I saw. So instead of answering as such, I guessed. I don’t remember if I guessed right. I remember the doctor, the scariness, the stress, the tests, and trying to guess what I was supposed to see and say. I was perhaps four or five, and my dad was there in the dark doctor’s office, so I knew it was serious business.
I do not have stereopsis, or, what most people take for granted as three-dimensional vision. Stereopsis requires that both eyes track together, so that the brain can use the perfect disparity between the right and left eyes to judge depth. A few inches apart, they see a slightly different image and the visual cortex uses that difference to create the third dimension. It is a trick of the mind. The cells in the visual cortex of the brain that do this develop quite early, and they rely on sight from two properly aligned eyes.
What does this mean to a kid? I sucked at ball games, because judging the distance of a ball moving through the blue sky is pretty much the pinnacle of three-dimensional sight. I loved photography since before I can remember, and got my first camera for Christmas at age ten. I first thought I was trying to freeze and memorize images, just in case I went blind. Later I realized that using one eye to make two-dimensional images is my reality, so of course it comes naturally. Though I do wonder how others see photographs. While your two-dimension vision is no different than mine, it differs from your regular, three-dimensional vision. Mine does not. All the tricks my brain uses to judge depth are pretty much there in a photograph. So perhaps I’m good at relaying the third-dimension in only two. I can’t know.
I also realized in high school that I could play tennis, as long as there were no lobs, because my brain used the lines on the court to judge where the ball was. I liked that. I did not like 3-D movies, because they didn’t work. I saw a lot of lines. I didn’t and don’t like many movies because the brightness hurts my eyes, which are ultra-sensitive to light. Especially in a pitch black room.
These things I had figured out on my own. In the last few years, I’ve noticed even more. Partly due to technology, and perhaps partly due to yoga and meditation, and simply being more aware of my experience. This is getting a bit long, so I’ll save more on how I actually see for the next post.