The Ishihara test is a diagnostic tool for assessing deficiencies in color vision. It presents tester takers with numbers formed out of colored circles. These numbers are set against a background formed of further colored circles, in hues paired to assess color blindness. If the tester is unable to distinguish the number from the background, then they likely suffer color blindness. The test examines red-green color blindness. The test does not determine auditory acuity. Likewise it does not assess attention to stimuli, nor the ability to discriminate between changes in a stimulus.

Saccades can occur voluntarily or involuntarily. The voluntary saccades allow you to rapidly change fixation from one object to another. This action allows you to read by rapidly changing your fixation on different words and locations on the page. Vergence is when two eyes move in the opposite direction, this would not allow you to focus on the words on the page, making reading impossible (trying to read while "crossing" your eyes). Smooth pursuit is when the eyes smoothly follow a moving object, words on a page are stationary in most situations. Reflexive eye movements are involuntary whereas reading is a voluntary action. 

The magnocellular system is colorblind and it carries low spatial frequency information and high temporal frequency information in the more dorsal regions of the posterior half of the brain. This means the visual information it carries is about large, fast things leading to the processing of information about location. The other answer options pertain to the parvocellular system.

Glaucoma is caused by pressure due to the blockage of flow of aqueous liquid. Therefore, detection of pressure build-up before it damages the optic nerve head is the correct prevention method. Injection of anti-vascular drugs is used for Macular degeneration that is detected early enough. Control of your diet and blood pressure may delay peripheral degeneration and diabetic retinopathy. Antibiotics and hygiene can prevent blindness caused by Trachoma.

Gestalt principles are common sense principles for explaining why we see what we see. Simplicity is the common sense principle that the simplest shape is usually the right explanation for an image. Synchrony is the principle defined as features that appear and disappear at the same time belong together. Connectedness is the term for the principle that connected feature belong together. Proximity is the Gestalt principle for things that are close together belong together, and similarity is the principle that things that look alike probably come from the same source.

The Opponent/Process Theory is defined as three types of receptor cones in the retina for color processing, each handling a different pair of colors, when only one can fire at a given time. This is used to explain color blindness—only one color in a pair fires appropriately—and afterimages.

Rhodopsin is a biological pigment specifically found in rods in the retina. It specifically reacts when exposed to light, and is considered rather sensitive--it enables humans to see in low light conditions by photobleaching when exposed to light. 

The occipital lobe is responsible for eyesight processing. Other areas of eyesight processing involve cranial nerves, Meyer's loop and Baum's loop which send information to the occipital lobe to be processed. On the other hand, the rest of the listed choices are incorrect. The frontal lobe is responsible for reward, attention, short-term memory tasks, planning, and motivation. It is also the part that tells a person if they are making a good decision or not. The parietal lobe is responsible for processing sensory information from your environment. Last, the temporal lobe is responsible for hearing and memory input.

Abnormalities in the shape of the eye are the cause of all of nearsightedness, farsightedness, and astigmatism. Typically nearsightedness and farsightedness are caused by irregularities in the lens of the eye. This causes light to improperly be focused relative to the retina. As a result, either near or far images will appear out of focus, due to the improper adjustment of the lens. In the case of astigmatism, the cornea as well as the lens may be implicated, in which case the an abnormality in the curvature of this front portion of the eye contributes to blurry vision. All of these defects may be corrected by LASIK, or corrective lenses. Damage to the nervous system or the visual cortex would lead to partial or total cortical blindness, not to these conditions. Though some psychological disorders are implicated in visual deficits, they do not play a role in these three.

Hearing aids replace the cochlea and the essential apparatuses contained within. Most significantly, they perform the role of the receptor cells lining the basilar membrane within the cochlea, which are responsible for the transduction of information carried by physical energy into electrical energy within the nervous system. This type of hearing aid is of value to an individual suffering from conduction deafness, which is deafness brought about due to damage to the apparatuses of the ear. An example of this would be a soldier deafened by exploding ordinance, or an airport worker continuously exposed to the loud volume of plane engines without sufficient ear protection. Cortical deafness, also known as nerve or sensorineural deafness, however, is brought about through damage to the auditory regions of the nervous system. As such, an individual with perfectly healthy ears might be rendered deaf due to damage caused by a stroke or brain trauma. This kind of deafness cannot be rectified by hearing aids, or any other form of extant medical intervention. "Ossicle" may refer to the bones of the inner ears (the auditory ossicles), but is not itself the name for a form of deafness nor is "auditory."