Auto-refractor

This machine gives an indication of patient's prescription, and should be done along with the other "pre-testing" functions (prepping the exam forms, NCT and lensometer) on each patient prior to calling the doc.

It sends an infrared light beam into the eye, and measures how the light reflects back out, using a bracketing approach. This is why the patient sees the Christmas tree go in and out of focus a few times. At the same time, it measures the keratometry readings - the curvature of the central part of the cornea (called "K" readings). This is sometimes useful for fitting contact lenses.

To operate it, first seat the patient and adjust the table height up or down to match the person's chin height (or just a little lower). Have them lean forward and place the chin on the chin-rest, and the forehead along the top bar. This helps to keep the eye and head still, which is necessary to achieve accurate measurement. Tell them to look at the blurry Christmas tree in the center, and that it will go in and out of focus. For young kids, if they're too short, sometimes having them sit on mom's knee helps. For poorly sighted patients who say they can't see the tree, just tell them to look straight ahead and try to keep the eye still. For obese patients, keep the chin rest fairly low so they can lean forward and down.

If the machine is in "sleep" mode, click the joystick button to wake it up. Usually we do the right eye first. Start with the auto-refractor fairly far away from the patient and move the instrument base left to right to find the eye in the TV screen. Slowly advance the machine toward the patient until the eye is centered and in clear focus. The joy stick provides a little finer control of positioning, both left and right, and up and down via rotation. The goal is to get the central reflection within the square marked on the screen, and keep it there throughout the measuring process. If the eye moves too much, inaccuracy or even complete failure to measure may occur. In some patients (elderly, Parkinson's active kids) this will be inevitable, and any reading you can obtain is better than nothing.

Once the "R OK" message appears on the screen, you can slide over to the left eye and repeat the process. If you get "K ERR" don't worry too much, the refraction is much more important. If you get no readings, click the button to start the auto-measuring process again. The machine is set up to print automatically. Extra copies can be printed manually via the print button. Record the info in the appropriate place on the exam forms, and tape the print out into the file (inside back cover is a good place).