Cultures are not often taken or needed as most cases resolve either with time or typical antibiotics. Swabs for bacterial culture are necessary if the history and signs suggest bacterial conjunctivitis but there is no response to topical antibiotics. Viral culture may be appropriate in epidemic case clusters.

A patch test is used to identify the causative allergen in the case where conjunctivitis is caused by allergy.

Conjunctival scrapes for cytology can be useful in detecting chlamydial and fungal infections, allergy, and dysplasia, but are rarely done because of the cost and the general lack of laboratory staff experienced in handling ocular specimens. Conjunctival incisional biopsy is occasionally done when granulomatous diseases ("e.g.", sarcoidosis) or dysplasia are suspected.

Classification can be either by cause or by extent of the inflamed area.

Diagnosis of the condition is done via a physical examination under a slit lamp. Cultures of debris are occasionally collected for bacterial or fungal testing.

Cultures of the eyelid margins can be a clear indicator for patients suffering from recurrent anterior blepharitis with severe inflammation, in addition to patients who are not responding to therapy. Measurements of tear osmolarity may be beneficial in diagnosing concurrent dry eye syndrome (DES), which may be responsible for overlapping symptoms and would allow the physician to decipher between conditions and move forward with the most beneficial protocol for the patient. Consequently, the measurement of tear osmolarity has various limitations in differentiating between aqueous deficiencies and evaporative dry eye. Microscopic evaluation of epilated eyelashes may reveal mites, which have been evident in cases of chronic blepharoconjunctivitis. A biopsy of the eyelid can also determine the exclusion of carcinoma, therapy resistance, or unifocal recurrent chalazia.

Treatment of herpes of the eye is different based on its presentation: epithelial keratitis is caused by live virus while stromal disease is an immune response and metaherpetic ulcer results from inability of the corneal epithelium to heal:

A specific clinical diagnosis of HSV as the cause of dendritic keratitis can usually be made by ophthalmologists and optometrists based on the presence of characteristic clinical features. Diagnostic testing is seldom needed because of its classic clinical features and is not useful in stromal keratitis as there is usually no live virus. Laboratory tests are indicated in complicated cases when the clinical diagnosis is uncertain and in all cases of suspected neonatal herpes infection:

- Corneal smears or impression cytology specimens can be analyzed by culture, antigen detection, or fluorescent antibody testing. Tzanck smear, i.e.Papanicolaou staining of corneal smears, show multinucleated giant cells and intranuclear inclusion bodies, however, the test is low in sensitivity and specificity.

- DNA testing is rapid, sensitive and specific. However, its high cost limits its use to research centers.

- Demonstration of HSV is possible with viral culture.

- Serologic tests may show a rising antibody titer during primary infection but are of no diagnostic assistance during recurrent episodes.

The disease incidence varies widely depending on the geographical location. The most extensive epidemiological survey on this subject has been carried out by Dharmasena et al. who analysed the number of neonates who developed neonatal conjunctivitis in England from 2000 to 2011. In addition to the incidence of this sight threatening infection they also investigated the time trends of the disease. According to them the incidence of Neonatal conjunctivitis (Ophthalmia Neonatorum) in England was 257 (95% confidence interval: 245 to 269) per 100,000 in 2011.

Scleritis is best detected by examining the sclera in daylight; retracting the lids helps determine the extent of involvement. Other aspects of the eye exam (i.e. visual acuity testing, slit lamp examination, etc.) may be normal. Scleritis may be differentiated from episcleritis by using phenylephrine or neosynephrine eye drops, which causes blanching of the blood vessels in episcleritis, but not in scleritis.

Ancillary tests CT scans, MRIs, and ultrasonographies can be helpful, but do not replace the physical examination.

If the allergen is encountered and the symptoms are mild, a cold compress can be used to provide relief.

A detailed history allows physicians to determine whether the presenting symptoms are due to an allergen or another source. Diagnostic tests such as conjunctival scrapings to look for eosinophils are helpful in determining the cause of the allergic response. Antihistamines, medication that stabilizes mast cells, and NSAIDs are safe and usually effective. Corticosteroids are reserved for more severe cases of ocular allergy disease, and their use should be monitored by an eye care physician due to possible side-effects. When an allergen is identified, the person should avoid the allergen as much as possible.

Antibiotic ointment is typically applied to the newborn's eyes within 1 hour of birth as prevention against gonococcal ophthalmia. This maybe erythromycin, tetracycline, or silver nitrate.

Ligneous conjunctivitis may be managed by topical treatments of plasminogen, topical and subconjunctival fresh frozen plasma, and fibrinolytic therapy.

Scleritis can be classified as anterior scleritis and posterior scleritis. Anterior scleritis is the most common variety, accounting for about 98% of the cases. It is of two types : Non-necrotising and necrotising. Non-necrotising scleritis is the most common, and is further classified into diffuse and nodular type based on morphology. Necrotising scleritis accounts for 13% of the cases. It can occur with or without inflammation.

Diagnosis of FVR is usually by clinical signs, especially corneal ulceration. Definitive diagnosis can be done by direct immunofluorescence or virus isolation. However, many healthy cats are subclinical carriers of feline herpes virus, so a positive test for FHV-1 does not necessarily indicate that signs of an upper respiratory tract infection are due to FVR. Early in the course of the disease, histological analysis of cells from the tonsils, nasal tissue, or nictitating membrane (third eyelid) may show inclusion bodies (a collection of viral particles) within the nucleus of infected cells.

Conjunctival concretions can be seen easily by everting the eyelid. The projecting concretions should be removed. Removal is easily performed by a doctor. For example, using needles or sharp knife removes the concretion, under a local light anesthesia of the conjunctiva.

DLK is usually seen after refractive surgery. Neutrophils infiltrate the corneal stroma in a diffuse, multifocal pattern. Infiltration is confined to the surgical flap interface with no posterior or anterior extension, and overlying epithelium most often remains intact. As it is a sterile process, cultures based on swab tests are negative.

Conjunctivitis is prevalent among children of the highlands of Ecuador. The finding supports the hypothesis that prolonged exposure to the sun at altitude—in the less dense atmosphere (with the resultant lower UV absorption)—is the main cause of the disease.

Actinic conjunctivitis is an inflammation of the eye contracted from prolonged exposure to actinic (ultraviolet) rays. Symptoms are redness and swelling of the eyes. Most often the condition is caused by prolonged exposure to Klieg lights, therapeutic lamps, or acetylene torches. Other names for the condition include Klieg conjunctivitis, eyeburn, arc-flash, welder's conjunctivitis, flash keratoconjunctivitis, actinic ray ophthalmia, x-ray ophthalmia, and ultraviolet ray ophthalmia.

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.

The main diagnosis technique is observing the area. Then blood tests can be done to determine if there is a pre-existing condition. Family history can be considered because some of the related causes/conditions can be inherited.

Histopathological findings from affected humans indicate that wound healing is impaired due to a deficiency in plasmin-mediated extracellular fibrinolysis. Episodes may be triggered by minor trauma, eye surgery, or by systemic events such as infections or antifibrinolytic therapy. Histology shows amorphous subepithelial deposits of eosinophilic material consisting predominantly of fibrin.

There is a vaccine for FHV-1 available (ATCvet code: , plus various combination vaccines), but although it limits or weakens the severity of the disease and may reduce viral shedding, it does not prevent infection with FVR. Studies have shown a duration of immunity of this vaccine to be at least three years. The use of serology to demonstrate circulating antibodies to FHV-1 has been shown to have a positive predictive value for indicating protection from this disease.

Depending on severity, therapies may range from topical or oral anti-inflammatories to irrigation and surgical repair.

Ophthalmia (also called ophthalmitis) is inflammation of the eye. It is a medical sign which may be indicative of various conditions, including sympathetic ophthalmia (inflammation of both eyes following trauma to one eye), gonococcal ophthalmia, trachoma or "Egyptian" ophthalmia, ophthalmia neonatorum (a conjunctivitis of the newborn due to either of the two previous pathogens), photophthalmia and actinic conjunctivitis (inflammation resulting from prolonged exposure to ultraviolet rays), and others.

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.