There are over 1 million Cataract operations performed annually in the USA. Cataract surgery is an outpatient procedure with a very high success rate. Due to the lack of modern medical technology in the developing world, it is also the world's leading cause of blindness. Over 16 million people are blind from cataracts.
This complication of diabetes is a leading cause of blindness among middle-aged Americans. The longer a person has had diabetes the more apt they are to develop diabetic retinopathy. Laser surgery can slow the progression of this disease along with management of blood glucose levels. There are 2.4 million people blind from retinopathy worldwide.
This disease increases the fluid pressure inside the eye, leading to loss of side vision and eventually total blindness. The increased pressure destroys the optic nerve. With early detection, it can be kept under control with pressure reducing eye drops and surgery. Chances of developing it increase with age. There are over five million people blind from glaucoma worldwide.
Age-Related Macular Degeneration (AMD)
This is a degenerative disease of the macula; the macula is the part of the retina responsible for central vision. There is no way yet of repairing the vision that has been lost, but if detected early laser surgery can help slow the progression of the disease. (AMD) is the leading cause of vision loss in people over age 65. Eight million people are legally blind from macular degeneration worldwide and as the population ages this number is expected to grow.
Retinitis Pigmentosa (RP)
This rare inherited degenerative disease slowly destroys the retina. Signs of (RP) first show up in early childhood. The side vision is lost first. The disease progresses over many years leaving the person with only a small portion of their central vision. There is no cure for (RP) yet. There are 1.6 million people blind from (RP) worldwide.
Left Field Homonymous Hemianopia
A left (or right) homonymous hemianopia (also called hemianopsia) means that the patient cannot see anything in the entire left or right visual field in both eyes. Because both eyes are affected more or less equally, the location of the problem must be at the optic chiasm or further back along the visual pathways. Some patients may state, truthfully, that they cannot see anything in the affected visual field. But sometimes the patient may be able to fixate or look directly at or point to a visual object located in the affected visual field, even though they do not consciously "see" the object. This condition is referred to as "Blind Sight."
Left Field Homonymous Hemianopia with Macular Sparing
Sometimes a left homonymous hemianopia (hemianopsia) will not include the very central part of the visual field, called the macula. As a consequence, "...with macular sparing."
Migraine Fortification Phenomenon
Sometimes in a migraine, the patient will experience visual symptoms similar to that shown to the left. The center of the visual effect may be in the patients central vision or it may appear off to one side. First, the very central part of vision is affected with decreased vision and the shimmering appearance of lines as illustrated. As time goes by, the area of vision affected grows and when central vision may appear somewhat blurred, the shimmering lines expand outward and may engulf most of the visual field. The visual effect affects both eyes similarly. Once the visual effect diminishes, vision returns to normal and the patient may experience other symptoms of the migraine including headache, nausea, loss of balance, ringing in the ears and other body sensations.
Ring or Donut Scotoma
A ring or donut shaped scotoma is an area of reduced vision that forms a shape similar to a ring or donut - the patient can see fine in the center and off-center a little bit but then there is an area of reduced vision followed by another area or normal vision as depicted in the photograph. Sometimes the ring or donut will not be totally round or complete but may appear like two crescent moons facing each other. A ring scotoma is often an early sign of a serious retinal disease/degeneration such as retinitis pigmentosa or other type of rod-cone degeneration.
Scotomas Caused by Pituitary Tumors (Lesions)
Pituitary tumors (lesions, classic pituitary adenomas) can sometimes cause very different losses of vision in the left and right eyes. For example, as simulated in the pictures, with the left eye the patient may see clearly only on the right side while with the right eye the patient may see clearly only on the left side. If the scotomas (i.e., blind spots in vision) are large, the patient may experience unstable vision characterized by bouts of double vision (diplopia) and confusion with object localization in 3D space. Visual acuity may also be affected in one or both eyes, again sometimes very differently: Visual acuity can be 20/20 in one eye and the patient may only be able to count fingers with the other eye. Any field loss of vision warrants an immediate trip to the eye doctor; ASAP. Other types of pathology can also cause visual field losses, so just because you have a field loss does not mean that you have a pituitary tumor.
Left eye view shown in top photo, right eye view on bottom.