op-, opt-, optico-, opsi-, opso-, -opia, -ops, -opsia, -opsis, -opsy, -optic, -opic, -opy +

A person with achromatopsia, or someone who is completely colorblind, or nearly so, and who has very poor visual acuity (sharpness).

Their eyes do not adapt normally to higher levels of illumination and are very sensitive to light or who are photophobic.

A rare form of color vision impairment in which the world is seen only in black, white, and shades of gray.

This hereditary disorder of sight is the result of a lack of cone vision; that type of vision which is provided by the cone photoreceptors in the retina.

In the normal human eye, it is estimated that there are about six million cone photoreceptors that are located largely in the center of the retina.

Lacking cone photoreceptors, people with achromatopsia must rely on their rod photoreceptors. There are approximately 100 million rod photoreceptors which are located mainly around the periphery of the retina.

Rods saturate at higher levels of illumination and do not provide color vision or good detail vision.

The inability to discern blue colors.

A color blindness towards blue.

A condition of the eyes in which they are slanting.

Reduced capability, or the inability, to recognize green colors.

1. Motion blindness or an inability to perceive motion, despite stationary objects remaining more or less visible, due to brain damage disrupting input to the dorsal pathway.
2. A rare neuropsychological disorder, meaning it is a disorder between the nervous system and mental functions, or in this case between the brain and perception.

In this kind of disorder, the person affected by it cannot perceive motion. It may be caused by disruption to the cortical area in the middle temporal lobe.

It can also be caused as a side effect of certain antidepressant drugs, a result of damage by a stroke, or by certain brain surgeries.

Diplopia, or the perception of two images of a single object; also called, double vision and binocular polyopia.

1. Reduction, or dimness, of vision; especially, that in which there is no apparent pathologic condition of the eye.
2. Impairment of vision without detectable organic lesion of the eye.
3. Poor vision caused by abnormal development of visual areas of the brain in response to abnormal visual stimulation during early development.

1. Medical management, or treatment, of reduced vision.
2. Treatment of amblyopia.

A reference to an impairment of vision in an eye that is not caused by structural damage or a physical defect.

Any climbing, woody vine, or shrub belonging to the genus Ampelopsis; of the grape family, having small greenish flowers and inedible berries.

The presence of monocular diplopia in both eyes.

Double vision in both eyes.

1. A difference in the refractive power of the two eyes.
2. Having eyes of unequal refractive power.
3. A condition in which the refractive power of one eye differs from that of the other.