Prior to any physical examination, the diagnosis of keratoconus frequently begins with an ophthalmologist's or optometrist's assessment of the person's medical history, particularly the chief complaint and other visual symptoms, the presence of any history of ocular disease or injury which might affect vision, and the presence of any family history of ocular disease. An eye chart, such as a standard Snellen chart of progressively smaller letters, is then used to determine the person's visual acuity. The eye examination may proceed to measurement of the localized curvature of the cornea with a manual keratometer, with detection of irregular astigmatism suggesting a possibility of keratoconus. Severe cases can exceed the instrument's measuring ability. A further indication can be provided by retinoscopy, in which a light beam is focused on the person's retina and the reflection, or reflex, observed as the examiner tilts the light source back and forth. Keratoconus is amongst the ophthalmic conditions that exhibit a scissor reflex action of two bands moving toward and away from each other like the blades of a pair of scissors.

If keratoconus is suspected, the ophthalmologist or optometrist will search for other characteristic findings of the disease by means of slit lamp examination of the cornea. An advanced case is usually readily apparent to the examiner, and can provide for an unambiguous diagnosis prior to more specialized testing. Under close examination, a ring of yellow-brown to olive-green pigmentation known as a Fleischer ring can be observed in around half of keratoconic eyes. The Fleischer ring, caused by deposition of the iron oxide hemosiderin within the corneal epithelium, is subtle and may not be readily detectable in all cases, but becomes more evident when viewed under a cobalt blue filter. Similarly, around 50% of subjects exhibit Vogt's striae, fine stress lines within the cornea caused by stretching and thinning. The striae temporarily disappear while slight pressure is applied to the eyeball. A highly pronounced cone can create a V-shaped indentation in the lower eyelid when the person's gaze is directed downwards, known as Munson's sign. Other clinical signs of keratoconus will normally have presented themselves long before Munson's sign becomes apparent, and so this finding, though a classic sign of the disease, tends not to be of primary diagnostic importance.

A handheld keratoscope, sometimes known as "Placido's disk", can provide a simple noninvasive visualization of the surface of the cornea by projecting a series of concentric rings of light onto the cornea. A more definitive diagnosis can be obtained using corneal topography, in which an automated instrument projects the illuminated pattern onto the cornea and determines its topography from analysis of the digital image. The topographical map indicates any distortions or scarring in the cornea, with keratoconus revealed by a characteristic steepening of curvature which is usually below the centreline of the eye. The technique can record a snapshot of the degree and extent of the deformation as a benchmark for assessing its rate of progression. It is of particular value in detecting the disorder in its early stages when other signs have not yet presented.

Once keratoconus has been diagnosed, its degree may be classified by several metrics:

- The steepness of greatest curvature from 'mild' ( 52 D);

- The morphology of the cone: 'nipple' (small: 5 mm and near-central), 'oval' (larger, below-center and often sagging), or 'globus' (more than 75% of cornea affected);

- The corneal thickness from mild (> 506 μm) to advanced (< 446 μm).

Increasing use of corneal topography has led to a decline in use of these terms.

Blurry vision may result from any number of conditions not necessarily related to refractive errors. The diagnosis of a refractive error is usually confirmed by an eye care professional during an eye examination using a large number of lenses of different optical powers, and often a retinoscope (a procedure entitled "retinoscopy") to measure objectively in which the patient views a distant spot while the clinician changes the lenses held before the patient's eye and watches the pattern of reflection of a small light shone on the eye. Following that "objective refraction" the clinician typically shows the patient lenses of progressively higher or weaker powers in a process known as "subjective refraction".

Cycloplegic agents are frequently used to more accurately determine the amount of refractive error, particularly in children

An automated refractor is an instrument that is sometimes used in place of retinoscopy to objectively estimate a person's refractive error. Shack–Hartmann wavefront sensor and its inverse can also be used to characterize eye aberrations in a higher level of resolution and accuracy.

Vision defects caused by refractive error can be distinguished from other problems using a pinhole occluder, which will improve vision only in the case of refractive error.

Hyperopia is typically classified according to clinical appearance, its severity, or how it relates to the eye's accommodative status.

There are three clinical categories of hyperopia.

- Simple hyperopia

- Pathological hyperopia

- Functional hyperopia

There are also three categories severity:

- Low

- Moderate

- High

Other common types of refractive errors are near-sightedness, astigmatism, and presbyopia.

Treatment options include contact lenses, intrastromal corneal ring segments, corneal collagen cross-linking, or corneal transplant.

When cross-linking is performed only after the cornea becomes distorted, vision remains blurry even though the disease is stabilised. As a result, combining corneal collagen cross-linking with LASIK ('LASIK Xtra') aims to strengthen the cornea at the point of surgery and may be useful in cases where a very thin cornea is expected after the LASIK procedure. This would include cases of high spectacle power and people with thin corneas before surgery. Definitive evidence that the procedure can reduce the risk of corneal ectasia will only become available a number of years later as corneal ectasia, if it happens, usually occurs in the late post-operative period. Some study show that combining LASIK with cross-linking adds refractive stability to hyperopic treatments and may also do the same for very high myopic treatments.

In 2016, the FDA approved the KXL system and two photoenhancers for the treatment of corneal ectasia following refractive surgery.

Corneal perforation can be diagnosed by using the Seidel test. Any aqueous leakage is revealed during the Seidel test confirms corneal perforation. A fluorescence strip is wiped over the wound. If the clear aqueous humor from the eye runs through the yellow stain, the patient tests positive for corneal perforation.

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.

Intraocular pressure should be measured as part of the routine eye examination.

It is usually only elevated by iridocyclitis or acute-closure glaucoma, but not by relatively benign conditions.

In iritis and traumatic perforating ocular injuries, the intraocular pressure is usually low.

In an eye with iridocyclitis, (inflammation of both the iris and ciliary body), the involved pupil will be smaller than the uninvolved, due to reflex muscle spasm of the sphincter muscle of the iris.

Generally, conjunctivitis does not affect the pupils.

With acute angle-closure glaucoma, the pupil is generally fixed in mid-position, oval, and responds sluggishly to light, if at all.

Shallow anterior chamber depth may indicate a predisposition to one form of glaucoma (narrow angle) but requires slit-lamp examination or other special techniques to determine it.

In the presence of a "red eye", a shallow anterior chamber may indicate acute glaucoma, which requires immediate attention.

The center of the cornea shows normal thickness, with an intact central epithelium, but the inferior cornea exhibits a peripheral band of thinning, to about 1–2 mm. The portion of the cornea that is immediately adjacent to the limbus is spared, usually a strip of about 1–2 mm. In PMD we can see high against the rule astigmatism along with horizontal bow ties. The inferior peripheral thinning is seen between the 4 o'clock and 8 o'clock positions.

PMD lacks apical corneal scarring, Rizutti's phenomenon, Munson's sign, and the central corneal thickness is usually normal.

The gold standard diagnostic test for PMD is corneal topography. However, it may not as specific as corneal pachymetry, because corneal topography only evaluates the degree and distribution of surface irregularities on the cornea, not the thickness of the cornea. Corneal topography may show a "crab claw-like" appearance, a finding that is seen in both keratoconus and in pellucid marginal degeneration. Thus, if corneal topography is used for diagnosis, it should be in conjunction with clinical findings of peripheral, inferior corneal thinning.

Although corneal abrasions may be seen with ophthalmoscopes, slit lamp microscopes provide higher magnification which allow for a more thorough evaluation. To aid in viewing, a fluorescein stain that fills in the corneal defect and glows with a cobalt blue-light is generally instilled first.

A careful search should be made for any foreign body, in particular looking under the eyelids. Injury following use of hammers or power-tools should always raise the possibility of a penetrating foreign body into the eye, for which urgent ophthalmology opinion should be sought.

A diagnosis of far-sightedness can be made via a slit lamp test which examines the cornea, conjunctiva, and iris.

In severe cases of hyperopia from birth, the brain has difficulty in merging the images that each individual eye sees. This is because the images the brain receives from each eye are always blurred. A child with severe hyperopia can never see objects in detail. If the brain never learns to see objects in detail, then there is a high chance of one eye becoming dominant. The result is that the brain will block the impulses of the non-dominant eye. In contrast, the child with myopia can see objects close to the eye in detail and does learn at an early age to see detail in objects.

The erosion may be seen by an eye doctor using the magnification of a biomicroscope or slit lamp. Usually fluorescein stain must be applied first and a cobalt blue-light used, but may not be necessary if the area of the epithelial defect is large. Optometrists and ophthalmologists have access to the slit lamp microscopes that allow for this more-thorough evaluation under the higher magnification. Mis-diagnosis of a scratched cornea is fairly common, especially in younger patients.

Complications are the exception rather than the rule from simple corneal abrasions. It is important that any foreign body be identified and removed, especially if containing iron as rusting will occur.

Occasionally the healed epithelium may be poorly adherent to the underlying basement membrane in which case it may detach at intervals giving rise to recurrent corneal erosions.

The treatment of corneal perforation depends on the location, severity and the cause of damage

- Tissue adhesive can be used to seal small perforation, but this method cannot be used to treat perforations larger than 1 mm.

- Non infected corneal perforation generally heals when a pressure bandage is used.

- For certain types of corneal perforations, lamellar keratoplasty is used as treatment.

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

Keratoglobus continues to be a somewhat mysterious disease, but it can be successfully managed with a variety of clinical and surgical techniques. The patient is at risk for globe perforation because the thinned out cornea is extremely weak.

It is a much rarer condition than keratoconus, which is the most common of the cornea. Similar to keratoconus it is typically diagnosed in the patient's adolescent years and attains its most severe state in the twenties and thirties.

Before LASIK surgery, people must be examined for possible risk factors such as keratoconus.

Abnormal corneal topography compromises of keratoconus, pellucid marginal degeneration, or forme fruste keratoconus with an I-S value of 1.4 or more is the most significant risk factor. Low age, low residual stromal bed (RSB) thickness, low preoperative corneal thickness, and high myopia are other important risk factors.

NK is diagnosed on the basis of the patient's medical history and a careful examination of the eye and surrounding area.

With regard to the patient's medical history, special attention should be paid to any herpes virus infections and possible surgeries on the cornea, trauma, abuse of anaesthetics or chronic topical treatments, chemical burns or, use of contact lenses. It is also necessary to investigate the possible presence of diabetes or other systemic diseases such as multiple sclerosis.

The clinical examination is usually performed through a series of assessments and tools:

- General examination of cranial nerves, to determine the presence of nerve damage.

- Eye examinations:

1. Complete eye examination: examination of the eyelids, blink rate, presence of inflammatory reactions and secretions, corneal epithelial alterations.

2. Corneal sensitivity test: performed by placing a cotton wad or cotton thread in contact with the corneal surface: this only allows to determine whether corneal sensitivity is normal, reduced or absent; or using an esthesiometer that allows to assess corneal sensitivity.

3. Tear film function test, such as Schirmer's test, and tear film break-up time.

4. Fluorescein eye stain test, which shows any damage to the corneal and conjunctival epithelium

Prophylaxis consists of periodic administration of Vitamin A supplements. WHO recommended schedule, which is universally recommended is as follows:

- Infants 6–12 months old and any older children weighing less than 8 kg - 100,000 IU orally every 3–6 months

- Children over 1 year and under 6 years of age - 200,000 IU orally every 6 months

- Infants less than 6 months old, who are not being breastfed - 50,000 IU orally should be given before they attain the age of 6 months

The diagnosis is clinical. The intraocular pressure (IOP) can be measured in the office in a conscious swaddled infant using a Tonopen or hand-held Goldmann tonometer. Usually, the IOP in normal infants is in the range of 11-14 mmHg. Buphthalmos and Haab's striae can often be seen in case of congenital glaucoma.

Given that episodes tend to occur on awakening and managed by use of good 'wetting agents', approaches to be taken to help prevent episodes include:

- Environmental:

- ensuring that the air is humidified rather than dry, not overheated and without excessive airflow over the face. Also avoiding irritants such as cigarette smoke.

- use of protective glasses especially when gardening or playing with children.

- General personal measures:

- maintaining general hydration levels with adequate fluid intake.

- not sleeping-in late as the cornea tends to dry out the longer the eyelids are closed.

- Pre-bed routine:

- routine use of long-lasting eye ointments applied before going to bed.

- occasional use of the anti-inflammatory eyedrop FML (prescribed by an ophthalmologist or optometrist) before going to bed if the affected eye feels inflamed, dry or gritty

- use of a hyperosmotic (hypertonic) ointment before bed reduces the amount of water in the epithelium, strengthening its structure

- use the pressure patch as mentioned above.

- use surgical tape to keep the eye closed (if Nocturnal Lagophthalmos is a factor)

- Waking options:

- learn to wake with eyes closed and still and keeping artificial tear drops within reach so that they may be squirted under the inner corner of the eyelids if the eyes feel uncomfortable upon waking.

- It has also been suggested that the eyelids should be rubbed gently, or pulled slowly open with your fingers, before trying to open them, or keeping the affected eye closed while "looking" left and right to help spread lubricating tears. If the patient's eyelids feel stuck to the cornea on waking and no intense pain is present, use a fingertip to press firmly on the eyelid to push the eye's natural lubricants onto the affected area. This procedure frees the eyelid from the cornea and prevents tearing of the cornea.

There are a number of different treatments to deal with TSPK. Symptoms may disappear if untreated, but treatment may decrease both the healing time and the chances of remission.

- PRK laser eye surgery may cure this disease (NOTE: A full clinical study has not been done, but a case study of one person was reported in 2002 PRK-pTK as a treatment).

- Artificial tear eye-drops or ointments may be a suitable treatment for mild cases.

- Low-dosage steroidal eye-drops, such as prednisone, fluorometholone, loteprednol (Lotemax 0.5%) or rimexolone. Steroidal drops should be used with caution and the eye pressure should be regularly checked during treatment.

- Soft contact lenses.

- Ciclosporin is an experimental treatment for TSPK. It is usually used during transplants as it reduces the immune system response.

- Tacrolimus (Protopic 0.03% ointment) is also an experimental treatment.

- Laser eye treatment.

- Amniotic membrane (Case Study)

Treatment depends on the cause of the keratitis. Infectious keratitis can progress rapidly, and generally requires urgent antibacterial, antifungal, or antiviral therapy to eliminate the pathogen. Antibacterial solutions include levofloxacin, gatifloxacin, moxifloxacin, ofloxacin. It is unclear if steroid eye drops are useful or not.

In addition, contact lens wearers are typically advised to discontinue contact lens wear and replace contaminated contact lenses and contact lens cases. (Contaminated lenses and cases should not be discarded as cultures from these can be used to identify the pathogen).

Aciclovir is the mainstay of treatment for HSV keratitis and steroids should be avoided at all costs in this condition. Application of steroids to a dendritic ulcer caused by HSV will result in rapid and significant worsening of the ulcer to form an 'amoeboid' or 'geographic' ulcer, so named because of the ulcer's map like shape.