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.

The diagnosis is made by an ophthalmologist/optometrist correlating typical history, symptoms and signs. Many times it may be missed and misdiagnosed as bacterial ulcer. A definitive diagnosis is established only after a positive culture report (lactophenol cotton blue, calcoflour medium), typically taking a week, from the corneal scraping. Recent advances have been made in PCR ref 3./immunologic tests which can give a much quicker result.

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.

Prevention of trauma with vegetable / organic matter, particularly in agricultural workers while harvesting can reduce the incidence of fungal keratitis. Wearing of broad protective glasses with side shields is recommended for people at risk for such injuries.

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.

The cornerstone of diagnosis is an accurate history, and a good clinical examination of the eye, to eliminate traumatic uveitis. Ultrasonography is a useful tool, as it can detect a thickened iris, but only in the hands of an expert.

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.

Diagnosis is done by direct observation under magnified view of slit lamp revealing the ulcer on the cornea. The use of fluorescein stain, which is taken up by exposed corneal stroma and appears green, helps in defining the margins of the corneal ulcer, and can reveal additional details of the surrounding epithelium. Herpes simplex ulcers show a typical dendritic pattern of staining. Rose-Bengal dye is also used for supra-vital staining purposes, but it may be very irritating to the eyes. In descemetoceles, the Descemet's membrane will bulge forward and after staining will appear as a dark circle with a green boundary, because it does not absorb the stain. Doing a corneal scraping and examining under the microscope with stains like Gram's and KOH preparation may reveal the bacteria and fungi respectively. Microbiological culture tests may be necessary to isolate the causative organisms for some cases. Other tests that may be necessary include a Schirmer's test for keratoconjunctivitis sicca and an analysis of facial nerve function for facial nerve paralysis.

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.

A positive VDRL of Treponema pallidum immobilization test confirms diagnosis of luetic(syphilitic) interstitial keratitis

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.

To detect "Acanthamoeba" on a contact lens in a laboratory, the contact lens is placed on a non-nutrient agar saline plate seeded with a gram-negative bacteria such as "E. coli". If "Acanthamoeba" are present, they will reproduce readily and become visible on the plate under 10-20X objective on an inverted microscope. Polymerase chain reaction can also be used to confirm a diagnosis of "Acanthamoeba" keratitis, especially when contact lenses are not involved. "Acanthameoba" is also characterized by a brawny edema and hazy view into the anterior chamber. Late stages of the disease also produces a ring shaped corneal ulcer. Signs and symptoms include severe pain, severe keratitis (similar to stromal herpetic disease), corneal perineuritis, and ring ulcer (late in the disease process).

During an acute flare-up, therapy is targeted at reducing the inflammation present, and dilating the pupil. Mydriasis is important, as pupillary constriction is the primary reason for pain. Anti-inflammatory therapy is usually given both systemically, often in the form of flunixin meglumine, and topically, as prednisolone acetate. The mydriatic of choice is atropine. In the periods between acute attacks, no therapy has been shown to be beneficial.

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.

According to the American Optometric Association, the following steps can be taken to prevent "Acanthamoeba" keratitis:

- Always wash and dry your hands before handling contact lenses, ordinary water should never come in contact with your lenses.

- Rub and rinse the surface of the contact lens before storing.

- Use only sterile products recommended by your optometrist to clean and disinfect your lenses. Saline solution and rewetting drops are not designed to disinfect lenses.

- Avoid using tap water to wash or store contact lenses.

- Contact lens solution must be discarded upon opening the case, and fresh solution used each time the lens is placed in the case.

- Replace lenses using your doctor’s prescribed schedule.

- Do not sleep in contact lenses unless prescribed by your doctor and never after swimming.

- Never swap lenses with someone else.

- Never put contact lenses in your mouth.

- See your optometrist regularly for contact lens evaluation.

In the United Kingdom, NGU is more often called non-specific urethritis; "" is a medical term meaning "specific cause has not been identified", and in this case refers to the detection of urethritis, and the testing for but found negative of gonorrhea. In this sense, the most likely cause of NSU is a chlamydia infection.

However, the term NSU is sometimes distinguished and used to mean that both gonorrhea and chlamydia have been ruled out. Thus, depending on the sense, chlamydia can either be the most likely cause or have been ruled out, and frequently detected organisms are "Ureaplasma urealyticum" and "Mycoplasma hominis".

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

Previous long-standing eye infection which possibly during childhood time recalled as being treated with antibiotic and/or hospitalized over long period of time.

Some infections may scar the cornea to limit vision. Others may result in perforation of the cornea, (an infection inside the eye), or even loss of the eye. With proper medical attention, infections can usually be successfully treated without long-term visual loss.

Diagnosis of nocardiosis can be done by a doctor using various techniques. These techniques include, but are not limited to: a chest x-rays of the lung, a bronchoscopy, a brain/lung/skin biopsy, or a sputum culture.

However, diagnosis may be difficult. Nocardiae are gram positive weakly acid-fast branching rod-shaped bacteria and can be visualized by a modified Ziehl–Neelsen stain like Fite-Faraco method. In the clinical laboratory, routine cultures may be held for insufficient time to grow nocardiae, and referral to a reference laboratory may be needed for species identification. Infiltration and pleural effusion are usually seen via x-ray.

It has been easy to test for the presence of gonorrhea by viewing a Gram stain of the urethral discharge under a microscope: The causative organism is distinctive in appearance; however, this works only with men because other non-pathogenic gram-negative microbes are present as normal flora of the vagina in women. Thus, one of the major causes of urethritis can be identified (in men) by a simple common test, and the distinction between gonococcal and non-gonococcal urethritis arose for this reason.

Non-gonococcal urethritis (NGU) is diagnosed if a person with urethritis has no signs of gonorrhea bacteria on laboratory tests. The most frequent cause of NGU (23%-55% of cases) is "C. trachomatis".