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Cataracts: Cloudiness over the eye's lens, cause blurring of vision, halos around lights, and sensitivity to glare. [5] It is also the main cause of blindness worldwide. [2] Glaucoma: Increased intraocular pressure (pressure in the eye) cause progressive optic neuropathy that leads to optic nerve damage, visual field defects and blindness. [6]
Entoptic images have a physical basis in the image cast upon the retina. Hence, they are different from optical illusions, which are caused by the visual system and characterized by a visual percept that (loosely said) appears to differ from reality.
The left and right eye see different, seemingly random, dot patterns; a person viewing through both eyes sees a combination of both left and right visual field disturbances. While seeing the phenomenon, lightly pressing inward on the sides of the eyeballs at the lateral canthus causes the movement to stop being fluid and the dots to move only ...
Cyanopsia does not develop into a chronic condition and shows no cumulative effects. In cases associated with cataract surgery, it diminishes as the eye adjusts. Medication-induced cyanopsia resolves with the stopping of the medication, and no long-term recurrence patterns have been observed.
Amblyopia, also called lazy eye, is a disorder of sight in which the brain fails to fully process input from one eye and over time favors the other eye. [1] It results in decreased vision in an eye that typically appears normal in other aspects. [ 1 ]
With intense lighting, the eye can constrict the pupil, yet allow enough light to reach the retina. The more the eye resembles a pinhole camera, the less it depends on focusing through the lens. [d] In other words, the degree of decoupling between focusing and convergence needed to visualize an autostereogram is reduced. This places less strain ...
Optical defocus can result from incorrect corrective lenses or insufficient accommodation, as, e.g., in presbyopia from the aging eye. As said above, light rays from a point source are then not focused to a single point on the retina but are distributed in a little disk of light, called the blur disk. Its size depends on pupil size and amount ...
In this example the first eye, with a −1.00 diopter prescription, is the stronger eye, needing only slight correction to sharpen the image formed, and hence a thin spectacle lens. The second eye, with a −4.00 diopter prescription, is the weaker eye, needing moderate correction to sharpen the image formed, and hence a moderately thick ...