My first blog post was written about a disorder I grew up with as a child called strabismus. When a person is diagnosed with strabismus, one eye is turned so that it is receiving a view of the world from an abnormal angle. My current post will be about something that relates to strabismus, called stereoblindness.

Stereoblindness is an inability to make use of binocular disparity as a depth cue. This term is typically used to describe individuals with normal vision in both eyes. Stereoblindness is usually a secondary effect of childhood visual disorders, such as strabismus (like I had). Approximately 3-5% of the population lacks stereoscopic depth perception.

In order to understand stereoblindness, one should be able to understand binocular disparity first. Binocular disparity is the difference between the two retinal images of the same world. Disparity is the basis for a vivid perception of the three-dimensionality of the world that is not available with purely one-eyed vision. Binocular disparity is a depth cue that helps the eyes determine the relative distance of objects in space.

Because I had strabismus as a child, I am considered a person that experiences stereoblindness, someone that is unable to use binocular disparity as a depth cue. I was able to find this out when I was reading about binocular disparity in Chapter 6 in our textbook. There are pictures in the book called stereograms, a diagram or image that gives a three-dimensional representation of a solid object or surface. When viewing these pictures, an individual should be able to cross or uncross their eyes and experience disparity. This is a task that I was repeatedly unable to do, and it is because I had strabismus as a child. This is something that truly interested me, because I didn’t realize that having strabismus as a child could have lasting effects later on in my life. I also found it someone frustrating that I couldn’t look at these pictures and understand them fully. Regardless, I found the topic of stereoblindness to be very interesting to read about.

Below is a picture of binocular disparity:

Strabismus is a misalignment of the two eyes such that a single object in space is imaged on the fovea of one eye, and on a nonfoveal area of the other turned eye. In other words, one eye is turned so that it is receiving a view of the world from an abnormal angle. This is also referred to as a “lazy eye.” Strabismus can result in amblyopia and serious damage to the eye. Amblyopia is a developmental disorder characterized by reduced spatial vision in an otherwise healthy eye, even with proper correction for refractive error.

I can easily relate to the concept of strabismus because I had it when I was a child. It definitely was not an easy thing to grow up with. When I was about four years old, I began to realize that I was seeing double. When I would be looking at an object or a person, there would literally be two people in front of me or two teddy bears sitting on my bed. My parents also started to notice that my left eye looked like it was almost crossing over my right one when I would look straight ahead. In the picture below, my eye looked somewhat like the very last set of eyes. They took me to my local eye doctor and I was pronounced with strabismus. I had to get surgery in my left eye (the eye with strabismus) to correct my vision. In addition to surgery, I had to wear a patch over my right eye (my good eye) in order to help correct the left eye and “force” it to work. I also was prescribed for eyeglasses that I still wear to this day. My prescription has obviously gotten better, but my right eye is still stronger than my left eye. When I take my glasses off it’s very easy for me to notice this. Growing up with strabismus was something very hard to deal with for my parents and myself, but if my doctors didn’t catch it early, I would most likely be almost blind in my left eye today.