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.

Astigmatism may be corrected with eyeglasses, contact lenses, or refractive surgery. Various considerations involving eye health, refractive status, and lifestyle determine whether one option may be better than another. In those with keratoconus, certain contact lenses often enable patients to achieve better visual acuity than eyeglasses. Once only available in a rigid, gas-permeable form, toric lenses are now available also as soft lenses.

Laser eye surgery (LASIK and PRK) is successful in treating astigmatism.

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.

Low order aberrations (hyperopia, Myopia and regular astigmatism), are correctable by eyeglasses, soft contact lenses and refractive surgery. Neither spectacles nor soft contact lenses nor routine keratorefractive surgery adequately corrects high order aberrations. Significant high order aberration usually requires a rigid gas-permeable contact lens for optimal visual rehabilitation.

Customized Wavefront-guided refractive corneal laser treatments are designed to reduce existing aberrations and to help prevent the creation of new aberrations. The wavefront map of the eye may be transferred to a Lasik system and enable the surgeon to treat the aberration. Perfect alignment of the treatment and the pupil on which the Wavefront is measured is required, which is usually achieved through iris feature detection. An efficient eye tracking system and small spot size laser is necessary for treatment . Wavefront customization of ablation increases the depth of ablation because additional corneal tissue must be ablated to compensate for the high order aberrations. Actual results with Wavefront guided LASIK showed that not only it cannot remove HOA but also the optical aberrations are increased. However, the amount of increase in aberrations are less than conventional Lasik. Corneal optical aberrations after photorefractive keratectomy with a larger ablation zone and a transition zone are less pronounced and more physiologic than those associated with first-generation (5 mm) ablations with no transition zone. An upcoming systematic review will seek to compare the safety and effectiveness of wavefront excimer laser refractive surgery with conventional excimer laser refractive surgery, and will measure differences in residual higher order aberrations between the two procedures.

Aspherical intraocular lenses (IOLs) have been used clinically to compensate for positive corneal spherical aberrations. Although Aspherical IOLs may give better contrast sensitivity, it is doubtful, whether they have a beneficial effect on distance visual acuity. Conventional (not Aspherical) IOLs give better depth of focus and better near vision. The reason for improved depth of focus in conventional lenses is linked to residual spherical aberration. The small improvement in depth of focus with the conventional IOLs enhances uncorrected near vision and contribute to reading ability.

Wavefront customized lenses can be used in eyeglasses. Based on Wavefront map of the eye and with the use of laser a lens is shaped to compensate for the aberrations of the eye and then put in the eyeglasses. Ultraviolet Laser can alter the refractive index of curtain lens materials such as epoxy polymer on a point by point basis in order to generate the desired refractive profile.

Wavefront customized contact lenses can theoretically correct HOA. The rotation and decentration reduces the predictability of this method.

According to an American study nearly three in 10 children (28.4%) between the ages of five and 17 have astigmatism. A recent Brazilian study found that 34% of the students in one city were astigmatic. Regarding the prevalence in adults, a recent study in Bangladesh found that nearly 1 in 3 (32.4%) of those over the age of 30 had astigmatism.

A Polish study published in 2005 revealed "with-the-rule astigmatism" may lead to the onset of myopia.

A number of studies have found the prevalence of astigmatism increases with age.

In general, strabismus can be approached and treated with a variety of procedures. Depending on the individual case, treatment options include:

- Correction of refractive errors by glasses

- Prism therapy (if tolerated, to manage diplopia)

- Patching (mainly to manage amblyopia in children and diplopia in adults)

- Botulinum toxin injection

- Surgical correction

Surgical correction of the hypertropia is desired to achieve binocularity, manage diplopia and/or correct the cosmetic defect. Steps to achieve the same depend on mechanism of the hypertropia and identification of the offending muscles causing the misalignment. Various surgical procedures have been described and should be offered after careful examination of eyes, including a detailed orthoptic examination focussing on the disturbances in ocular motility and visual status. Specialty fellowship trained pediatric ophthalmologists and strabismus surgeons are best equipped to deal with these complex procedures.

The eye, like any other optical system, suffers from a number of specific optical aberrations. The optical quality of the eye is limited by optical aberrations, diffraction and scatter. Correction of spherocylindrical refractive errors has been possible for nearly two centuries following Airy's development of methods to measure and correct ocular astigmatism. It has only recently become possible to measure the aberrations of the eye and with the advent of refractive surgery it might be possible to correct certain types of irregular astigmatism.

The appearance of visual complaints such as halos, glare and monocular diplopia after corneal refractive surgery has long been correlated with the induction of optical aberrations. Several mechanisms may explain the increase in the amount of higher-order aberrations with conventional eximer laser refractive procedures: a change in corneal shape toward oblateness or prolateness (after myopic and hyperopic ablations respectively), insufficient optical zone size and imperfect centration. These adverse effects are particularly noticeable when the pupil is large.

Myopia, with or without astigmatism, is the most common eye condition in horses.

Several types of occlusion myopia have been recorded in tree shrews, macaques, cats and rats, deciphered from several animal-inducing myopia models. Preliminary laboratory investigations using retinoscopy of 240 dogs found myopic problems with varying degrees of refraction errors depending on the breed. In cases involving German Shepherds, Rottweilers and Miniature horses, the refraction errors were indicative of myopia. Nuclear sclerosis of the crystalline lens was noticed in older dogs.

Experiments into newborn macaque monkeys have revealed that surgically fusing the eyelid for one year results in eye deterioration as the eye has not had a chance to grow and develop. Keeping monkeys in the dark for a similar period, however, does not lead to myopia. In 1996, Maurice and Mushin conducted tests on rabbits by raising their body temperatures and intraocular pressures (IOP) and noted that while younger rabbits were prone to developing myopia, older rabbits were not. Some tests have revealed that myopia in some animals can be improved with eye drops containing zinc, by increasing the activity of superoxide dismutase (SOD).

The rhesus monkey's vision amplitude reduction is noticeable in its second decade of life; however the condition does not impede normal functioning. Older rhesus monkeys have more difficulty accommodating this reduction in vision amplitude, encountering difficulty in focussing on objects at close range, even objects on the ground within an arm's length.

In Central Park Zoo, New York, several myopic animals have been reported, including a 39-year-old elephant, a Cape buffalo, and some monkeys. Young elephants and other animals are said to be myopia free. Pet dogs with progressive myopia have been reported.

The early stages of pellucid marginal degeneration may also be managed with soft contact lenses. Success has been shown with the use of rigid gas permeable contact lenses combined with over-refraction. Patients wearing contacts dont report increased problems with glare and contrast sensitivity, but it is not clear if this is due to the corneal disease, or the contact lenses themselves.

New studies found that the use of Scleral contact lens, a type of rigid gas permeable (RGP) lens, may be a good option for most patients with PMD. Most of these lenses are in the range of 15.5mm to 18.0mm in diameter. Regardless of the lens size, it is thought that the larger the RGP lens will in most cases be more comfortable then standard rigid corneal lenses, and at times more comfortable than soft lenses, regardless of the fact that it is a rigid lens. The highlight to the scleral design and the correction of eye disorders such as pellucid marginal degeneration is that vision with these types of lenses is exceptional when fit correctly.

While preventive measures, such as taking breaks from activities that cause eye strain are suggested, there are certain treatments which a person suffering from the condition can take to ease the pain or discomfort that the affliction causes. Perhaps the most effective of these is to remove all light sources from a room and allow the eyes to relax in darkness. Free of needing to focus, the eyes will naturally relax over time, and relieve the discomfort that comes with the strain. Cool compresses also help to some degree, though care should be taken to not use anything cold enough to damage the eyes themselves (such as ice). A number of companies have released "computer glasses" which, through the use of specially tinted lenses, help alleviate many of the factors which cause eye strain, though they do not completely prevent it. Rather, they just make it harder to strain the eye.

Hypertropia may be either congenital or acquired, and misalignment is due to imbalance in extraocular muscle function. The superior rectus, inferior rectus, superior oblique, and inferior oblique muscles affect the vertical movement of the eyes. These muscles may be either paretic, restrictive (fibrosis) or overactive effect of the muscles. Congenital cases may have developmental abnormality due to abnormal muscle structure, usually muscle atrophy / hypertrophy or rarely, absence of the muscle and incorrect placement.

Specific & common causes include:

- Superior oblique Palsy / Congenital fourth nerve palsy

- Inferior oblique overaction

- Brown's syndrome

- Duane's retraction syndrome

- Double elevator palsy

- Fibrosis of rectus muscle in Graves Disease (most commonly inferior rectus is involved)

- Surgical trauma to the vertical muscles (e.g. during scleral buckling surgery or cataract surgery causing iatrogenic trauma to the vertical muscles).

Sudden onset hypertropia in a middle aged or elderly adult may be due to compression of the trochlear nerve and mass effect from a tumor, requiring urgent brain imaging using MRI to localise any space occupying lesion. It could also be due to infarction of blood vessels supplying the nerve, due to diabetes and atherosclerosis. In other instances it may be due to an abnormality of neuromuscular transmission, i.e., Myasthenia Gravis.

Most patients can be treated non-surgically with eyeglasses, or contact lenses.

Pseudomyopia refers to an intermittent and temporary shift in refractive error of the eye towards myopia, in which the focusing of light in front of the retina is due to a transient spasm of the ciliary muscle causing an increase in the refractive power of the eye. It may be either organic, through stimulation of the parasympathetic nervous system, or functional in origin, through eye strain or fatigue of ocular systems. It is common in young adults who have active accommodation, and classically occurs after a change in visual requirements, such as students preparing for an exam, or a change in occupation.

The major symptom is intermittent blurring of distance vision particularly noticeable after prolonged periods of near work, and symptoms of asthenopia. The vision may clear temporarily using concave (minus) lenses. The diagnosis is done by cycloplegic refraction using a strong cycloplegic like atropine or homatropine eye drops. Accommodative amplitude and facility may be reduced as a result of the ciliary muscle spasm.

Treatment is dependent on the underlying aetiology. Organic causes may include systemic or ocular medications, brain stem injury, or active ocular inflammation such as uveitis. Functional pseudomyopia is managed though modification of working conditions, an updated refraction, typically involving a reduction of a myopic prescription to some lower myopic prescription, or through appropriate ocular exercises.

Sometimes asthenopia can be due to specific visual problems—for example, uncorrected refraction errors or binocular vision problems such as accommodative insufficiency or heterophoria. It is often caused by the viewing of monitors such as those of computers or phones for prolonged periods of time.

As it is associated with excessive sun or wind exposure, wearing protective sunglasses with side shields and/or wide brimmed hats and using artificial tears throughout the day may help prevent their formation or stop further growth. Surfers and other water-sport athletes should wear eye protection that blocks 100% of the UV rays from the water, as is often used by snow-sport athletes. Many of those who are at greatest risk of pterygium from work or play sun exposure do not understand the importance of protection.

Amniotic membrane transplantation is an effective and safe procedure for pterygium removal. Amniotic membrane transplantation offers practical alternative to conjunctival auto graft transplantation for extensive pterygium removal. Amniotic membrane transplantation is tissue that is acquired from the innermost layer of the human placenta and has been used to replace and heal damaged mucosal surfaces including successful reconstruction of the ocular surface. It has been used as a surgical material since the 1940s, and has been shown to have a strong anti-adhesive effect.

Using an amniotic graft facilitates epithelialization, and has anti-inflammatory as well as surface rejuvenation properties. Amniotic membrane transplantation can also be fixated to the sclera using sutures, or glue adhesive. Amniotic membrane by itself does not provide an acceptable recurrence rate.

Cycloplegic drugs are generally muscarinic receptor blockers. These include atropine, cyclopentolate, homatropine, scopolamine and tropicamide. They are indicated for use in cycloplegic refraction (to paralyze the ciliary muscle in order to determine the true refractive error of the eye) and the treatment of uveitis. All cycloplegics are also mydriatic (pupil dilating) agents and are used as such during eye examination to better visualize the retina.

When cycloplegic drugs are used as a mydriatic to dilate the pupil, the pupil in the normal eye regains its function when the drugs are metabolized or carried away. Some cycloplegic drugs can cause dilation of the pupil for several days. Usually the ones used by ophthalmologists or optometrists wear off in hours, but when the patient leaves the office strong sunglasses are provided for comfort.

Lenticonus (/len·ti·co·nus/ (len″tĭ-ko´nus)) [lens + L. conus, cone] is a rare congenital anomaly of the eye characterized by a conical protrusion on the crystalline lens capsule and the underlying cortex. It can reach a diameter of 2 to 7 mm. The conus may occur anteriorly or posteriorly. If the bulging is spherical, instead of conical, the condition is referred to as "lentiglobus". It produces a decrease in visual acuity and irregular refraction that cannot be corrected by either spectacle or contact lenses.

Biomicroscopically "lenticonus" is characterized by a transparent, localized, sharply demarcated conical projection of the lens capsule and cortex, usually axial in localization. In an early stage, retro-illumination shows an «oil droplet» configuration. Using a narrow slit, the image of a conus is observed. In a more advanced stage associated subcapsular and cortical opacities appear. Retinoscopically the oil droplet produces a pathognomonic scissors movement of the light reflex. This phenomenon is due to the different refraction in the central and the peripheral area of the lens. Ultrasonography also can illustrate the existence of a "lenticonus". A-scan ultrasonography may reveal an increased lens thickness and B- scanultrasonography may show herniated lenticular material, suggestive of a lenticonus. Amblyopia, cataract, strabismus and loss of central fixation may be observed in association with lenticonus posterior. Cataract, flecked retinopathy, posterior polymorphous dystrophy and corneal arcus juvenilis may be encountered in association with lenticonus anterior that occurs as a part of the Alport syndrome.

Exist two distinct types of "lenticonus" based on the face of the lens affected.

Cycloplegia is paralysis of the ciliary muscle of the eye, resulting in a loss of accommodation. Because of the paralysis of the ciliary muscle, the curvature of the lens can no longer be adjusted to focus on nearby objects. This results in similar problems as those caused by presbyopia, in which the lens has lost elasticity and can also no longer focus on close-by objects. Cycloplegia with accompanying mydriasis (dilation of pupil) is usually due to topical application of muscarinic antagonists such as atropine and cyclopentolate.

Spaceflight induced visual impairment is hypothesized to be a result of increased intracranial pressure. The study of visual changes and intracranial pressure (ICP) in astronauts on long-duration flights is a relatively recent topic of interest to Space Medicine professionals. Although reported signs and symptoms have not appeared to be severe enough to cause blindness in the near term, long term consequences of chronically elevated intracranial pressure is unknown.

NASA has reported that fifteen long-duration male astronauts (45–55 years of age) have experienced confirmed visual and anatomical changes during or after long-duration flights. Optic disc edema, globe flattening, choroidal folds, hyperopic shifts and an increased intracranial pressure have been documented in these astronauts. Some individuals experienced transient changes post-flight while others have reported persistent changes with varying degrees of severity.

Although the exact cause is not known at this time, it is suspected that microgravity-induced cephalad fluid shift and comparable physiological changes play a significant role in these changes. Other contributing factors may include pockets of increased CO and an increase in sodium intake. It seems unlikely that resistive or aerobic exercise are contributing factors, but they may be potential countermeasures to reduce intraocular pressure (IOP) or intracranial pressure (ICP) in-flight.

Although a definitive cause (or set of causes) for the symptoms outlined in the Existing Long-Duration Flight Occurrences section is unknown, it is thought that venous congestion in the brain brought about by cephalad-fluid shifts may be a unifying pathologic mechanism. Additionally, a recent study reports changes in CSF hydrodynamics and increased diffusivity around the optic nerve under simulated microgravity conditions which may contribute to ocular changes in spaceflight. As part of the effort to elucidate the cause(s), NASA has initiated an enhanced occupational monitoring program for all mission astronauts with special attention to signs and symptoms related to ICP.

Similar findings have been reported among Russian Cosmonauts who flew long-duration missions on MIR. The findings were published by Mayasnikov and Stepanova in 2008.

Animal research from the Russian Bion-M1 mission indicates duress of the cerebral arteries may induce reduced blood flow, thereby contributing to impaired vision.

On 2 November 2017, scientists reported that significant changes in the position and structure of the brain have been found in astronauts who have taken trips in space, based on MRI studies. Astronauts who took longer space trips were associated with greater brain changes.

Glossoptosis is a medical condition and abnormality which involves the downward displacement or retraction of the tongue. It may cause non-fusion of the hard palate causing cleft palate.

It is one of the features of Pierre Robin sequence and Down syndrome.

Mees' lines or Aldrich–Mees' lines, also called leukonychia striata, are white lines of discoloration across the nails of the fingers and toes (leukonychia).

Pili pseudoannulati (also known as "pseudo pili annulati") is an anomaly of human hair that mimics pili annulati; however, the two differ in that the light bands of pili annulati are caused by internal effects, whereas the bright segments of pili pseudoannulati are caused by reflection and refraction of light by flattened, twisted surfaces of hair.