Patients often ask me, “Dr. Bert, my vision is blurry far away, does that mean that I’m nearsighted or farsighted?” As confusing as this may be differentiating these terms, it is really not too difficult once one examines the word itself. When a patient’s vision is better at near and blurry at distance, the person is said to be nearsighted or sighted at near. The scientific term for this is myopia.
But…what actually is nearsightedness? Optically, the eye is very similar to a camera. With a camera, to get a clear picture, the object one is trying to photograph must be in perfect focus on the camera film (most of you young people who were born in the digital age will read this and question, “What is film?” Just humor me, okay). If the image is focused incorrectly in front of the film, it will produce a blurry photograph. The same goes with the eye.
An eye with no visual problems will come to focus on the retina (the back inside layer of the eye which processes light into electrical signals which go to the brain). If the image is focus incorrectly in front of the retina, the image will be blurry. This is nearsightedness or myopia. There are typically two reasons why the image would focus in front of the retina. Either the eye is too long, or the surface of the front of the eye is too curved.