Subtitle: Near Point of convergence and monocular accommodation Part 3 of 4
Description: In part 3 of this 4-part series. Dr. Corwin discusses near point of convergence and monocular accommodation
Faculty: Daniel Corwin, MD, MSCE
Bio: Assistant Professor of Pediatrics, Perelman School of Medicine at the University of Pennsylvania|Attending Physician and Director of Research Operations, Division of Emergency Medicine|Emergency Department Lead and Investigator, Minds Matter Concussion Program|Scientist, Center for Injury Research and Prevention Children's Hospital of Philadelphia
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- Next, we'll move on to our vision tests, which include near point of convergence and monocular accommodation. This involves having our patient bring an object as close as they can to their face before it either breaks into two or blurs. It's easiest to do this using a writing utensil that will have lettering vertically oriented on it, so I'll have Dr. Master take the pen and slowly bring it closer to her face. I'll warn her that it'll first blur, and then I want her to stop when it breaks into two, as if train tracks are splitting apart. I'm going to measure the distance from her forehead to where she stops. It's important to measure this rather than estimating a distance, so I'm using the backing of our Q-tip wrapping, which has a ruler on it. One could also use a tape measure. Next, we move to left monocular accommodation. It's the same maneuver, but with only one eye open, so Dr. Master will be closing her right eye, and again, bringing the pen as close as you can to her face until it now blurs. It will now break into two, and I will measure that distance. Then she'll bring the pen back out until it clears, switch eyes, so now close her left eye for right monocular accommodation. Slowly bring the pen closer to her face, again, until it blurs, and I'll once again measure that distance. In terms of cutoffs, for near point of convergence, normal is getting the object to within six centimeters of the face. For monocular accommodation, the normal distance increases by a little bit each year we age, but a general rule of thumb is 12 centimeters. Anything further out than 12 centimeters is an abnormal monocular accommodation.
