Nearsightedness, or myopia, occurs when the cornea has too much curvature or the eyeball is too long from front to back. Objects nearby appear in focus, but objects farther away are out of focus. Farsightedness, or hyperopia, occurs when the cornea has too little curvature or the eyeball is too short from front to back. … Continue reading
You’ve probably heard the term “cataract” but, if you’re like most people, you don’t actually know what it means. A cataract is a clouding of the eye’s crystalline lens, which sits behind the pupil and is responsible for focusing light. In a healthy eye, this lens is clear but over time proteins in the lens … Continue reading
The retina has a static contrast ratio of around 100:1 (about 6.5 f-stops). As soon as the eye moves (saccades) it re-adjusts its exposure both chemically and geometrically by adjusting the iris which regulates the size of the pupil. Initial dark adaptation takes place in approximately four seconds of profound, uninterrupted darkness; full adaptation through adjustments in retinal … Continue reading
Eye irritation has been defined as “the magnitude of any stinging, scratching, burning, or other irritating sensation from the eye”.[5] It is a common problem experienced by people of all ages. Related eye symptoms and signs of irritation are e.g. discomfort, dryness, excess tearing, itching, grating, sandy sensation, smarting, ocular fatigue, pain, scratchiness, soreness, redness, swollen … Continue reading
