"Looming" is a term used in the study of the perception, as it relates directly to psychology. Looming refers to the rapid expansion in the size of any given image. As the image becomes increasingly large on the perceiver's retina, i.e., when an object "looms", there is an automatic physiological response to perceive the object as an approaching object or surface, instead of one that is or receding. The type of mirage described as looming, in which distant objects appear much nearer than they actually are, is explained in the same way as the image of the ship, except that the image is not inverted; the density variations may also act as a magnifying glass.

"Visual looming", which is the expansion of the projection size of an object on the retina, is usually the indication of an approaching object. It is normally perceived as a threat for a possible collision and is sufficient to elicit avoidance and escape behaviors in animals. Also using the same basic principles in robotics have been successful.

There have been hypotheses about visual looming syndrome to be linked with several neural and gastroenterology diseases, such as celiac disease, epilepsy and migraines. Also physical differences between the eyes, such as astigmatism may be a factor. There have not been any empirical medical studies about the syndrome, though the consensus is all these may have affect on the muscular function of the eye, but most likely the visual looming syndrome is a separate symptom. There have been studies of a similar neurological situation. Gabbiani Peron has studied the "looming stimulus selectivity in a collision-detecting neuron". Beverley Regan has studied "Binocular and monocular stimuli for motion in depth". Moors P, Huygelier H, Wagemans J, de-Wit L, van Ee R; "Suppressed visual looming stimuli are not integrated with auditory looming signals"

Peer to peer studies have shown many common symptoms, such are "fear of pointy objects hitting the eye", "weird sensation behind the eyes", "difficulty in focusing on objects nearby, which are moving and are not operated by the observer, such as windscreen wipers or a pencil someone else is holding". In these studies visual looming syndrome is often referred as sharp edges eye syndrome (SEES).

Blindness can occur in combination with such conditions as intellectual disability, autism spectrum disorders, cerebral palsy, hearing impairments, and epilepsy. Blindness in combination with hearing loss is known as deafblindness.

It has been estimated that over half of completely blind people have non-24-hour sleep–wake disorder, a condition in which a person's circadian rhythm, normally slightly longer than 24 hours, is not entrained (synchronized) to the light/dark cycle.

Although the best outcome is achieved if treatment is started before age 8, children older than age 12 and some adults can show improvement in the affected eye. Children from 9 to 11 who wore an eye patch and performed near-point activities (vision therapy) were four times as likely to show a two-line improvement on a standard 11-line eye chart than children with amblyopia who did not receive treatment. Adolescents aged 13 to 17 showed improvement, as well, albeit to a lesser degree than younger children. Whether such improvements are only temporary, however, is uncertain, particularly if treatment is discontinued.

Tentative evidence shows that perceptual training may be beneficial in adults.

Virtual-reality computer games where each eye receives different signals of the virtual world that the player's brain must combine to successfully play the game have shown some promise in improving both monocularity in the affected eye, as well as binocularity.

Treatment of strabismic or anisometropic amblyopia consists of correcting the optical deficit (wearing the necessary spectacle prescription) and often forcing use of the amblyopic eye, by patching the good eye, or instilling topical atropine in the good eye, or both.

Concerning patching versus atropine, a drawback is seen in using atropine; the drops can have a side effect of creating nodules in the eye which a correctional ointment can counteract. One should also be wary of overpatching or overpenalizing the good eye when treating amblyopia, as this can create so-called "reverse amblyopia". Eye patching is usually done on a part-time schedule of about 4–6 hours a day. Treatment is continued as long as vision improves. It is not worthwhile continuing to patch for more than 6 months if no improvement continues. Treatment of individuals age 9 through to adulthood is possible through applied perceptual learning.

Deprivation amblyopia is treated by removing the opacity as soon as possible followed by patching or penalizing the good eye to encourage the use of the amblyopic eye. The earlier the treatment is initiated, the easier and faster the treatment is and the less psychologically damaging. Also, the chance of achieving 20/20 vision is greater if treatment is initiated early.

One of the German public health insurance providers, Barmer, has changed its policy to cover, as of 1 April 2014, the costs for an app for amblyopic children whose condition has so far not improved through patching. The app offers dedicated eye exercises which the patient performs while wearing an eyepatch.

The World Health Organization estimates that 80% of visual loss is either preventable or curable with treatment. This includes cataracts, onchocerciasis, trachoma, glaucoma, diabetic retinopathy, uncorrected refractive errors, and some cases of childhood blindness. The Center for Disease Control and Prevention estimates that half of blindness in the United States is preventable.

The simplest form of treatment for far-sightedness is the use of corrective lenses, eyeglasses or contact lenses. Eyeglasses used to correct far-sightedness have convex lenses.

There are also surgical treatments for far-sightedness:

- Photorefractive keratectomy (PRK)

- Laser assisted in situ keratomileusis (LASIK)

- Refractive lens exchange (RLE)

- Laser epithelial keratomileusis (LASEK)

In early stages of keratoconus, glasses or soft contact lenses can suffice to correct for the mild astigmatism. As the condition progresses, these may no longer provide the person with a satisfactory degree of visual acuity, and most practitioners will move to manage the condition with rigid contact lenses, known as rigid, gas-permeable, (RGP) lenses. RGP lenses provide a good level of visual correction, but do not arrest progression of the condition.

In people with keratoconus, rigid contact lenses improve vision by means of tear fluid filling the gap between the irregular corneal surface and the smooth regular inner surface of the lens, thereby creating the effect of a smoother cornea. Many specialized types of contact lenses have been developed for keratoconus, and affected people may seek out both doctors specialized in conditions of the cornea, and contact lens fitters who have experience managing people with keratoconus. The irregular cone presents a challenge and the fitter will endeavor to produce a lens with the optimal contact, stability and steepness. Some trial-and-error fitting may prove necessary.

How refractive errors are treated or managed depends upon the amount and severity of the condition. Those who possess mild amounts of refractive error may elect to leave the condition uncorrected, particularly if the patient is asymptomatic. For those who are symptomatic, glasses, contact lenses, refractive surgery, or a combination of the three are typically used.

Strategies being studied to slow worsening include adjusting working conditions, increasing the time children spend outdoors, and special types of contact lenses. In children special contact lenses appear to slow worsening of nearsightedness.

Traditionally, contact lenses for keratoconus have been the 'hard' or RGP variety, although manufacturers have also produced specialized 'soft' or hydrophilic lenses and, most recently, silicone hydrogel lenses. A soft lens has a tendency to conform to the conical shape of the cornea, thus diminishing its effect. To counter this, hybrid lenses have been developed which are hard in the centre and encompassed by a soft skirt. However, soft or earlier generation hybrid lenses did not prove effective for every person. Early generation lenses have been discontinued. The fourth generation of hybrid lens technology has improved, giving more people an option that combines the comfort of a soft lens with the visual acuity of an RGP lens.

Retinoschisis involving the central part of the retina secondary to an optic disc pit was erroneously considered to be a serous retinal detachment until correctly described by Lincoff as retinoschisis. Significant visual loss may occur and following a period of observation for spontaneous resolution, treatment with temporal peripapillary laser photocoagulation followed by vitrectomy and gas injection followed by face-down positioning is very effective in treating this condition.

In studies of the genetic predisposition of refractive error, there is a correlation between environmental factors and the risk of developing myopia. Myopia has been observed in individuals with visually intensive occupations. Reading has also been found to be a predictor of myopia in children. It has been reported that children with myopia spent significantly more time reading than non-myopic children who spent more time playing outdoors. Socioeconomic status and higher levels of education have also been reported to be a risk factor for myopia.

Synesthesia also has a number of practical applications, one of which is the use of 'intentional synesthesia' in technology.

Palinopsia from cerebrovascular accidents generally resolves spontaneously, and treatment should be focused on the vasculopathic risk factors. Palinopsia from neoplasms, AVMs, or abscesses require treatment of the underlying condition, which usually also resolves the palinopsia. Palinopsia due to seizures generally resolves after correcting the primary disturbance and/or treating the seizures. In persistent hallucinatory palinopsia, a trial of an anti-epileptic drug can be attempted. Anti-epileptics reduce cortical excitability and could potentially treat palinopsia caused by cortical deafferentation or cortical irritation. Patients with idiopathic hallucinatory palinopsia should have close follow-up.

This may be present in conditions causing traction on the retina especially at the macula. This may occur in:

a) The vitreomacular traction syndrome; b) Proliferative diabetic retinopathy with vitreoretinal traction; c) Atypical cases of impending macular hole.

The validity of Bálint's syndrome has been questioned by some. The components in the syndrome's triad of defects (simultanagnosia, oculomotor apraxia, optic ataxia) each may represent a variety of combined defects.

Synesthesia is found in at least 4.4% of the population, as a high estimate, which is equivalent to 1 in 23 people. This study had also concluded that one common form of synesthesia—grapheme-color synesthesia (colored letters and numbers) – is found in more than one percent of the population, and this latter prevalence of graphemes-color synesthesia has now been independently verified in a yet larger sample. Earlier estimates of the prevalence of synesthesia were based on "best-guess" estimations only ("e.g." 1 in 250,000) or had limitations in their methodologies because they required synesthetes to refer themselves for study ("e.g." 1 in 2000) and for this reason the authors of those studies had been moderate in their claims. Also, some individuals will not self-classify as synesthetes because they do not realize that their perceptions are different from those of everyone else.

The most common forms of synesthesia are those that trigger colors, and the most prevalent of all is day-color. Also relatively common is grapheme-color synesthesia. We can think of "prevalence" both in terms of how common is synesthesia (or different forms of synesthesia) within the population, or how common are different forms of synesthesia within synesthetes. So within synesthetes, forms of synesthesia that trigger color also appear to be the most common forms of synesthesia with a prevalence rate of 86% within synesthetes. In another study, music-color is also prevalent at 18–41%. Some of the rarest are reported to be auditory-tactile, mirror-touch, and lexical-gustatory.

There is research to suggest that the likelihood of having synesthesia is greater in people with autism.

In terms of the specific rehabilitation of visuoperceptual disorders such as Bálint's syndrome, the literature is extremely sparse. According to one study, rehabilitation training should focus on the improvement of visual scanning, the development of visually guided manual movements, and the improvement of the integration of visual elements. Very few treatment strategies have been proposed, and some of those have been criticized as being poorly developed and evaluated.

Three approaches to rehabilitation of perceptual deficits, such as those seen in Bálint's syndrome, have been identified:

1. The adaptive (functional) approach, which involves functional tasks utilising the person's strengths and abilities, helping them to compensate for problems or altering the environment to lessen their disabilities. This is the most popular approach.

2. The remedial approach, which involves restoration of the damaged CNS by training in the perceptual skills, which may be generalised across all activities of daily living. This could be achieved by tabletop activities or sensorimotor exercises.

3. The multicontext approach, which is based on the fact that learning is not automatically transferred from one situation to another. This involves practicing of a targeted strategy in a multiple environment with varied tasks and movement demands, and it incorporates self-awareness tasks.

A meta-analysis found evidence that does not support the use of patching.

Topical antibiotics may be reasonable.

One review has found that eye drops to numb the surface of the eye such as tetracaine improve pain; however, their safety is unclear. Another review did not find evidence of benefit and concluded there was not enough data on safety.

NSAID eye drops are also useful. A 2000 review found no good evidence to support medications that paralyze the iris. A 2017 review did not find evidence to suggest that topical NSAIDs would significantly reduce pain over standard-of-care treatments, but did find that NSAIDs could be associated with people using fewer pain medications by mouth.

Alice in Wonderland syndrome is a disorienting neuropsychological condition that affects perception. People experience size distortion such as micropsia, macropsia, pelopsia, or teleopsia. Size distortion may occur of other sensory modalities.

It is often associated with migraines, brain tumors, and the use of psychoactive drugs. It can also be the initial symptom of the Epstein–Barr virus (see mononucleosis). AiWS can be caused by abnormal amounts of electrical activity causing abnormal blood flow in the parts of the brain that process visual perception and texture.

Anecdotal reports suggest that the symptoms are common in childhood, with many people growing out of them in their teens. It appears that AiWS is also a common experience at sleep onset, and has been known to commonly arise due to a lack of sleep.

The average age of the start of Alice in Wonderland syndrome is six but it is very normal for some to experience the syndrome from childhood to their late 20s. It is also thought that this syndrome is hereditary because many parents that have AIWS report their children having it as well.

Hallucinatory palinopsia (Greek: "palin" for "again" and "opsia" for "seeing") is a subtype of palinopsia, a visual disturbance defined as the persistent or recurrence of a visual image after the stimulus has been removed. Palinopsia is a broad term describing a heterogeneous group of symptoms which is divided into hallucinatory palinopsia and illusory palinopsia. Hallucinatory palinopsia refers to the projection of an already-encoded visual memory and is similar to a complex visual hallucination: the creation of a formed visual image where none exists.

Hallucinatory palinopsia usually arises from posterior cortical lesions or seizures and can be the presenting symptom of a serious neurological disease. Hallucinatory palinopsia describes afterimages or scenes that are formed, long-lasting, high resolution, and isochromatic. The palinoptic images are not typically reliant on environmental parameters and often present with homonymous visual field deficits. Hallucinatory palinopsia occurs unpredictably and the persistent images can appear anywhere in the visual field, regardless of the location of the original stimulus. A patient will often have only a few episodes of hallucinatory palinopsia. Visual perseveration is synonymous with palinopsia.

Lattice corneal dystrophy type, also known as Biber-Haab-Dimmer dystrophy, is a rare form of corneal dystrophy. It has no systemic manifestations, unlike the other type of the dystrophy, Lattice corneal dystrophy type II. Lattice corneal dystrophy was first described by Swiss ophthalmologist Hugo Biber in 1890.

Lattice dystrophy gets its name from an accumulation of amyloid deposits, or abnormal protein fibers, throughout the middle and anterior stroma.