Oct 19 - 15 | Here is a straightforward question astutely posed by a young patient this week... "Why do I have to look into that mirror?" (He was referring to the small mirror at the end of the room that reflects the eye chart.) Answer: Ideally, an Optometrists "lane" (where the vision is tested) would be 6 meters long (20 feet). This distance is recognized as 'optical infinity' meaning that the vision system is completely relaxed at this distance like it should be if viewing a very distance object. The only reason that mirror systems are used is to create this minimum 6 meter testing distance in a smaller room to save $ and space.. e.g. if the exam chair is 3 meters from the mirror and the room is 4 meters long with the screen behind the patient... the optical length of the room is 3m + 4m = 7m. This is greater that 6 so the room has enough length to relax the patients' eyes. (the chart size would be adjusted accordingly). But if no mirrors were used and the room was only 3 metes long, the prescription determined would not be accurate for far away objects. Also of note... the mirror that you look into is specially designed so that no distortion occurs on the eye chart (front surface mirror). So now you know, dr.j Studioeyecare.com
