The last topic we discussed regarded Strabismus and the different types of Strabismus: Constant, Intermittent, and Alternating Strabismus. Today, I’ll be talking about how we as behavioral optometrists can use lenses and prism to help resolve strabismus along with vision therapy.
Lenses: We all know to some degree that lenses are used in glasses to help us to see better whether your nearsighted, farsighted, and/or astigmatic. Well lenses can also be used to help alter the posture of one’s eyes (“how straight the eyes are”). For instance, plus power used to correct farsightedness can also be used to relax posture. In other words, allow a strabismic patient that has their eyes turning in change to straightening out and not turn in while wearing glasses. Minus lenses used to correct nearsightedness can also be used to help bring the eyes in or “a flexing” posture. In other words, when one’s eye is too relaxed or positioned outward, these lenses can be used to help the eyes converge (come in) to again straighten out the eyes.
Prism: Prism is used to bend light in a certain direction, I won’t go into the optics of it, but basically it can be used to alter the direction of light. In strabismic patients we use prism to relax the demand on their binocular system to maintain fusion or use your eyes together as a team (binocularity). For instance, when one’s eye is turned out as in exotropia (a form of strabismus) we can use what we call base in prism to shift the light and resultant image out to where the eye likes to be thus giving the brain an opportunity to view the same target of regard or image at the same time out of both eyes. As a result, it then becomes easier for a strabismic patient to fuse or bring the images together to form one; creating binocularity! Base out prism is used to correct strabismic patients that have their eyes turn in aka esotropia. Vertical prism such as base up and down are used to correct a strabismic patient that has an eye that is turned up or down. Either way, prism is used to eliminate double vision as a result of strabismis and encourage binocularity. When I use the term “base” think of the base of a prism and then when I say base up, down, out or in, that refers to the direction the base is in when placed in front of the patient to use in their glasses. Please take note that the glasses would not look like there was literally prism in them as cosmetically that would look a little weird (; It’s actually a measurement for the lab to cut the lenses a certain way in order to create the prismatic affect.
Vision Therapy: Vision therapy involves doing exercises or activities in an attempt to develop awareness of binocualrity by teaching the patient what to see and feel when using their eyes correctly for functional binocularity! We use prism and lenses to manipulate light and challenge the patient to establish and sustain binocualrity. Vision therapy usually involves 1 hour sessions in office once or twice a week followed with homework for the patient to do every night at home in order to build those skills; practice makes perfect!
All in all, lenses, prism, and vision therapy is a credible and equal approach to treatment of strabismus. I encourage you to read more about vision therapy and the success stories that come about from doing it. Surgery isn’t always the answer when it comes to strabismus and this is definitely a less invasive and/or traumatic approach to treatment vs. surgery. Strabismis surgery is usually repeated in roughly 50% of cases so please consider vision therapy before surgery as an alternative to treatment since it could be the best decision you have ever made regarding you and/or your child’s vision.
