Mobility can be difficult for people with homonymous hemianopsia. “Patients frequently complain of bumping into obstacles on the side of the field loss, thereby bruising their arms and legs.”

People with homonymous hemianopsia often experience discomfort in crowds. “A patient with this condition may be unaware of what he or she cannot see and frequently bumps into walls, trips over objects or walks into people on the side where the visual field is missing.”

A related phenomenon is Hemispatial neglect, the possible neglect of the right or left. The patient is not conscious of its existence. The right side of the face is not shaven, make up is applied to one side of the face only and only half of a plate of food is eaten. This, however, is not necessarily due to a sensory abnormality, and is therefore distinct from hemianopsia.

Hemianopsia or hemianopia is a visual field loss on the left or right side of the vertical midline. It can affect one eye but usually affects both eyes. Homonymous hemianopsia, or homonymous hemianopia, is hemianopic visual field loss on the same side of both eyes. Homonymous hemianopsia occurs because the right half of the brain has visual pathways for the left hemifield of both eyes, and the left half of the brain has visual pathways for the right hemifield of both eyes. When one of these pathways is damaged, the corresponding visual field is lost.

A homonymous hemianopsia is the loss of half of the visual field on the same side in both eyes. The visual images that we see to the right side travel from both eyes to the left side of the brain, while the visual images we see to the left side in each eye travel to the right side of the brain. Therefore, damage to the right side of the posterior portion of the brain or right optic tract can cause a loss of the left field of view in both eyes. Likewise, damage to the left posterior brain or left optic radiation can cause a loss of the right field of vision.

A Heteronymous hemianopsia is the loss of half of the visual field on different sides in both eyes. It is separated into two categories:

- Binasal hemianopsia – the loss of the fields surrounding the nose;

- Bitemporal hemianopsia – the loss of the fields closest to the temples.

An anopsia or anopia is a defect in the visual field. If the defect is only partial, then the portion of the field with the defect can be used to isolate the underlying cause.

Types of partial anopsia:

- Hemianopsia

- Homonymous hemianopsia

- Heteronymous hemianopsia

- Binasal hemianopsia

- Bitemporal hemianopsia

- Superior hemianopia

- Inferior hemianopia

- Quadrantanopia

The term "anopsia" comes from the Ancient Greek ἀν- ("an-"), "un-" and ὄψις ("opsis") "sight".

The most common symptoms of acquired and transient cortical blindness include:

- A complete loss of visual sensation and of vision

- Preservation/sparing of the abilities to perceive light and/or moving, but not static objects (Riddoch syndrome)

- A lack of visual fixation and tracking

- Denial of visual loss (Anton–Babinski syndrome)

- Visual hallucinations

- Macular sparing, in which vision in the fovea is spared from the blindness.

A patient with cortical blindness has no vision but the response of his/her pupil to light is intact (as the reflex does not involve the cortex). Therefore, one diagnostic test for cortical blindness is to first objectively verify the optic nerves and the non-cortical functions of the eyes are functioning normally. This involves confirming that patient can distinguish light/dark, and that his/her pupils dilate and contract with light exposure. Then, the patient is asked to describe something he/she would be able to recognize with normal vision. For example, the patient would be asked the following:

- "How many fingers am I holding up?"

- "What does that sign (on a custodian's closet, a restroom door, an exit sign) say?"

- "What kind of vending machine (with a vivid picture of a well-known brand name on it) is that?"

Patients with cortical blindness will not be able to identify the item being questioned about at all or will not be able to provide any details other than color or perhaps general shape. This indicates that the lack of vision is neurological rather than ocular. It specifically indicates that the occipital cortex is unable to correctly process and interpret the intact input coming from the retinas.

Fundoscopy should be normal in cases of cortical blindness. Cortical blindness can be associated with visual hallucinations, denial of visual loss (Anton–Babinski syndrome), and the ability to perceive moving but not static objects. (Riddoch syndrome).

In bitemporal hemianopsia vision is missing in the outer (temporal or lateral) half of both the right and left visual fields. Information from the temporal visual field falls on the nasal (medial) retina. The nasal retina is responsible for carrying the information along the optic nerve, and crosses to the other side at the optic chiasm. When there is compression at optic chiasm the visual impulse from both nasal retina are affected, leading to inability to view the temporal, or peripheral, vision. This phenomenon is known as bitemporal hemianopsia. Knowing the neurocircuitry of visual signal flow through the optic tract is very important in understanding bitemporal hemianopsia.

Bitemporal hemianopsia most commonly occurs as a result of tumors located at the mid-optic chiasm. Since the adjacent structure is the pituitary gland, some common tumors causing compression are pituitary adenomas and craniopharyngiomas. Also another relatively common neoplastic cause is meningiomas. A cause of vascular origin is an aneurysm of the anterior communicating artery which arise superior to the chiasm, enlarge, and compress it from above.

Binasal hemianopsia (or binasal hemianopia) is the medical description of a type of partial blindness where vision is missing in the inner half of both the right and left visual field. It is associated with certain lesions of the eye and of the central nervous system, such as congenital hydrocephalus.

In binasal hemianopsia, vision is missing in the inner (nasal or medial) half of both the right and left visual fields. Information from the nasal visual field falls on the temporal (lateral) retina. Those lateral retinal nerve fibers do not cross in the optic chiasm. Calcification of the internal carotid arteries can impinge the uncrossed, lateral retinal fibers leading to loss of vision in the nasal field.

Note: Clinical testing of visual fields (by confrontation) can produce a false positive result (particularly in inferior nasal quadrants).

Quadrantanopia, quadrantanopsia, or quadrant anopia refers to an anopia affecting a quarter of the field of vision.

It can be associated with a lesion of an optic radiation. While quadrantanopia can be caused by lesions in the temporal and parietal lobes, it is most commonly associated with lesions in the occipital lobe.

A 2005 study examined 92 case studies since 1970 in which cerebral lesions affected color vision.

The severity and size of the visual field affected in cerebral achromatopsiacs vary from patient to patient.

Bitemporal hemianopsia, also known as bitemporal heteronymous hemianopsia or bitemporal hemianopia, is the medical description of a type of partial blindness where vision is missing in the outer half of both the right and left visual field. It is usually associated with lesions of the optic chiasm, the area where the optic nerves from the right and left eyes cross near the pituitary gland.

Homonymous denotes a condition which affects the same portion of the visual field of each eye.

Homonymous inferior quadrantanopia is a loss of vision in the same lower quadrant of visual field in both eyes whereas a homonymous superior quadrantanopia is a loss of vision in the same upper quadrant of visual field in both eyes.

A lesion affecting one side of the temporal lobe may cause damage to the inferior optic radiations (known as the temporal pathway or Meyer's loop) which can lead to superior quadrantanopia on the contralateral side of both eyes (colloquially referred to as "pie in the sky"); if the superior optic radiations (parietal pathway) are lesioned, the visual loss occurs on the inferior contralateral side of both eyes and is referred to as an inferior quadrantanopia.

Patients with cerebral achromatopsia deny having any experience of color when asked and fail standard clinical assessments like the Farnsworth-Munsell 100-hue test (a test of color ordering with no naming requirements). Patients may often not notice their loss of color vision and merely describe the world they see as being "drab". Most describe seeing the world in "shades of gray". This observation notes a key difference between cerebral and congenital achromatopsia, as those born with achromatopsia have never had an experience of color or gray.

Hallucinatory palinopsia consists of the following four symptom categories. A person often reports symptoms from multiple categories.

Formed image perseveration refers to a single, stationary object that remains fixed in one’s visual field. These pathological afterimages look realistic and have the same color and clarity as the original stimulus. The palinopsia lasts at least 15 seconds, but may persist for hours or days. For example, a patient sees a cat, and an identical copy of the cat remains fixed in the field of view for 30 minutes. A patient commonly complains of the perseverated fingers of an examiner. These afterimages often occur in visual field deficits but may occur anywhere in the visual field, regardless of the location of the original stimulus. The generation of the afterimages is not affected by external conditions such as the length of fixation, stimulus intensity, contrast, or motion. The palinoptic image can appear immediately after seeing the original image or may be delayed in time.

Bálint's syndrome is an uncommon and incompletely understood triad of severe neuropsychological impairments: inability to perceive the visual field as a whole (simultanagnosia), difficulty in fixating the eyes (oculomotor apraxia), and inability to move the hand to a specific object by using vision (optic ataxia). It was named in 1909 for the Austro-Hungarian neurologist and psychiatrist Rezső Bálint who first identified it.

Bálint's syndrome occurs most often with an acute onset as a consequence of two or more strokes at more or less the same place in each hemisphere. Therefore, it occurs rarely. The most frequent cause of complete Bálint's syndrome is said by some to be sudden and severe hypotension, resulting in bilateral borderzone infarction in the occipito-parietal region. More rarely, cases of progressive Bálint's syndrome have been found in degenerative disorders such as Alzheimer's disease or certain other traumatic brain injuries at the border of the parietal and the occipital lobes of the brain.

Lack of awareness of this syndrome may lead to a misdiagnosis and resulting inappropriate or inadequate treatment. Therefore, clinicians should be familiar with Bálint's syndrome and its various etiologies.

Bálint's syndrome symptoms can be quite debilitating since they impact visuospatial skills, visual scanning and attentional mechanisms. Since it represents impairment of both visual and language functions, it is a significant disability that can affect the patient's safety—even in one's own home environment, and can render the person incapable of maintaining employment. In many cases the complete trio of symptoms—inability to perceive the visual field as a whole (simultanagnosia), difficulty in fixating the eyes (oculomotor apraxia), and inability to move the hand to a specific object by using vision (optic ataxia)—may not be noticed until the patient is in rehabilitation. Therapists unfamiliar with Bálint's syndrome may misdiagnose a patient's inability to meet progress expectations in any of these symptom areas as simply indicating incapability of benefiting from further traditional therapy. The very nature of each Bálint symptom frustrates rehabilitation progress in each of the other symptoms. Much more research is needed to develop therapeutic protocols that address Bálint symptoms as a group since the disabilities are so intertwined.

Common causes of scotomata include demyelinating disease such as multiple sclerosis (retrobulbar neuritis), damage to nerve fiber layer in the retina (seen as cotton wool spots) due to hypertension, toxic substances such as methyl alcohol, ethambutol and quinine, nutritional deficiencies, vascular blockages either in the retina or in the optic nerve, stroke or other brain injury, and macular degeneration, often associated with aging. Scintillating scotoma is a common visual aura in migraine. Less common, but important because they are sometimes reversible or curable by surgery, are scotomata due to tumors such as those arising from the pituitary gland, which may compress the optic nerve or interfere with its blood supply.

Rarely, scotomata are . One important variety of bilateral scotoma may occur when a pituitary tumour begins to compress the optic chiasm (as distinct from a single optic nerve) and produces a bitemporal paracentral scotoma, and later, when the tumor enlarges, the scotomas extend out to the periphery to cause the characteristic bitemporal hemianopsia. This type of visual-field defect tends to be obvious to the person experiencing it but often evades early objective diagnosis, as it is more difficult to detect by cursory clinical examination than the classical or textbook bitemporal peripheral hemianopia and may even elude sophisticated electronic modes of visual-field assessment.

In a pregnant woman, scotomata can present as a symptom of severe preeclampsia, a form of pregnancy-induced hypertension. Similarly, scotomata may develop as a result of the increased intracranial pressure that occurs in malignant hypertension.

The scotoma is also caused by the aminoglycoside antibiotics mainly by Streptomycin.

Simultanagnosia (or simultagnosia) is a rare neurological disorder characterized by the inability of an individual to perceive more than a single object at a time. This type of visual attention problem is one of three major components (the others being optic ataxia and optic apraxia) of Bálint's syndrome, an uncommon and incompletely understood variety of severe neuropsychological impairments involving space representation (visuospatial processing). The term "simultanagnosia" was first coined in 1924 by Wolpert to describe a condition where the affected individual could see individual details of a complex scene but failed to grasp the overall meaning of the image.

Simultanagnosia can be divided into two different categories: dorsal and ventral. Ventral occipito-temporal lesions cause a mild form of the disorder, while dorsal occipito-parietal lesions cause a more severe form of the disorder.

Symptoms of CVI usually include several (but not necessarily all) of the following:

- The person with CVI exhibits variable vision. Visual ability can change from one day to the next but it can also fluctuate from minute to minute, especially when the person is tired. When undertaking critical activities, people with CVI should be prepared for their vision to fluctuate, by taking precautions such as always carrying a white cane even if they don't always use it to the full, or always having very large print available, just in case it's needed. (For example, consider the consequences of losing vision while giving a public speech). Managing fatigue can reduce fluctuations but does not eliminate them. Changes in environment, even minor, are mostly responsible for what appears to be variable vision.

- One eye may perform significantly worse than the other, and depth perception can be very limited (although not necessarily zero).

- The field of view may be severely limited. The best vision might be in the centre (like tunnel vision) but more often it is at some other point, and it is difficult to tell what the person is really looking at. Note that if the person also has a common ocular visual impairment such as nystagmus then this can also affect which part(s) of the visual field are best. (Sometimes there exists a certain gaze direction which minimises the nystagmus, called a "null point.")

- Even though the field of view may be very narrow indeed, it is often possible for the person to detect and track movement. Movement is handled by the 'V5' part of the visual cortex, which may have escaped the damage. Sometimes a moving object can be seen better than a stationary one; at other times the person can sense movement but cannot identify what is moving. (This can be annoying if the movement is prolonged, and to escape the annoyance the person may have to either gaze right at the movement or else obscure it.) Sometimes it is possible for a person with CVI to see things while moving their gaze around that they didn't detect when stationary. However, movement that is too fast can be hard to track; some people find that fast-moving objects "disappear." Materials with reflective properties, which can simulate movement, may be easier for a person with CVI to see. However, too many reflections can be confusing (see cognitive overload).

- Some objects may be easier to see than others. For example, the person may have difficulty recognising faces or facial expressions but have fewer problems with written materials. This is presumably due to the different way that the brain processes different things.

- Colour and contrast are important. The brain's colour processing is distributed in such a way that it is more difficult to damage, so people with CVI usually retain full perception of colour. This can be used to advantage by colour-coding objects that might be hard to identify otherwise. Sometimes yellow and red objects are easier to see, as long as this does not result in poor contrast between the object and the background.

- People with CVI strongly prefer a simplified view. When dealing with text, for example, the person might prefer to see only a small amount of it at once. People with CVI frequently hold text close to their eyes, both to make the text appear larger and to minimise the amount they must look at. This also ensures that important things such as letters are not completely hidden behind any scotomas (small defects in parts of the functioning visual field), and reduces the chances of getting lost in the text. However, the simplification of the view should not be done in such a way that it requires too rapid a movement to navigate around a large document, since too much motion can cause other problems (see above).

- In viewing an array of objects, people with CVI can more easily see them if they only have to look at one or two at a time. People with CVI also see familiar objects more easily than new ones. Placing objects against a plain background also makes them easier for the person with CVI to see.

- For the same reason (simplified view), the person may also dislike crowded rooms and other situations where their functioning is dependent on making sense of a lot of visual 'clutter'.

- Visual processing can take a lot of effort. Often the person has to make a conscious choice about how to divide mental effort between making sense of visual data and performing other tasks. For some people, maintaining eye contact is difficult, which can create problems in Western culture (for example, bonding can be difficult for some parents who have an infant with CVI, and lack of contact in an older child can cause others to regard him or her with suspicion).

- It can also be difficult for some people with CVI to look at an object and reach for it at the same time. Looking and reaching are sometimes accomplished as two separate acts: look, then look away and reach.

- People with CVI can sometimes benefit from a form of blindsight, which manifests itself as a kind of awareness of one's surroundings that cannot consciously be explained (for example, the person correctly guesses what they should do in order to avoid an obstacle but does not actually see that obstacle). However, this cannot be relied on to work all the time. In contrast, some people with CVI exhibit spatial difficulties and may have trouble moving about in their environment.

- Approximately one third of people with CVI have some photophobia. It can take longer than usual to adjust to large changes in light level, and flash photography can be painful. On the other hand, CVI can also in some cases cause a desire to gaze compulsively at light sources, including such things as candle flames and fluorescent overhead lights. The use of good task lighting (especially low-temperature lamps which can be placed at very close range) is often beneficial.

- Although people (with or without CVI) generally assume that they see things as they really are, in reality the brain may be doing a certain amount of guessing and "filling in", which is why people sometimes think they see things that turn out on closer inspection not to be what they seemed. This can occur more frequently when a person has CVI. Hence, a person with CVI can look at an optical illusion or abstract picture and perceive something that is significantly different from what a person without CVI will perceive.

The presence of CVI does not necessarily mean that the person's brain is damaged in any other way, but it can often be accompanied by other neurological problems, the most common being epilepsy.

The term dysmorphopsia comes from the Greek words dus (bad), morphè (form), and opsis (seeing).

Symptom-producing, or pathological, scotomata may be due to a wide range of disease processes, affecting any part of the visual system, including the retina (in particular its most sensitive portion, the macula), the optic nerve and even the visual cortex. A pathological scotoma may involve any part of the visual field and may be of any shape or size. A scotoma may include and enlarge the normal blind spot. Even a small scotoma that happens to affect central or macular vision will produce a severe visual disability, whereas a large scotoma in the more peripheral part of a visual field may go unnoticed by the bearer because of the normal reduced optical resolution in the peripheral visual field.

Patients with simultanagnosia, a component of Bálint's syndrome, have a restricted spatial window of visual attention and cannot see more than one object at a time in a scene that contains more than one object. For instance, if presented with an image of a table containing both food and various utensils, a patient will report seeing only one item, such as a spoon. If the patient's attention is redirected to another object in the scene, such as a glass, the patient will report that they see the glass but no longer see the spoon. As a result of this impairment, simultanagnosic patients often fail to comprehend the overall meaning of a scene.

In addition, patients note that one stationary object may spontaneously disappear from view as they become aware of another object in the scene.

Simultanagnosic patients often exhibit a phenomenon known as "local capture" where they only identify the local elements of stimuli containing local and global features. However, recent studies have demonstrated that implicit processing of the global structure can occur. With the appropriate stimulus conditions, explicit processing of the global form may occur. For example, a study performed with Navon hierarchical letters, which are large letters composed of smaller ones, revealed that the use of smaller and denser Navon letters biased the patient towards global processing.