Individuals with keratitis, present with the following signs and symptoms [7]:

• Development of redness in the eyes along with pain
• Increased discharge from the eyes
• Increased production of tears from the eyes
• Vision becomes blurred
• Development of photophobia, a condition characterized by sensitivity to light
• Decrease in vision
• Experiencing difficulty in opening the eyes due to irritation or pain

• Inflammation

  […] itis, inflammation] keratitis (kĕr′ə-tī′tĭs) n. [medical-dictionary.thefreedictionary.com]

  A disorder characterized by inflammation to the cornea of the eye. Area of epithelial tissue loss from corneal surface; associated with inflammatory cells in the cornea and anterior chamber. Inflammation of the cornea Inflammation of the cornea. [icd9data.com]

  Severe systemic allergies involving the eyes can also involve inflammation of the cornea. [mersi.com]

  Monosodium urate crystal deposition has been reported to occur in various parts of the eye, with and without ocular inflammation. Crystal deposition in the cornea is extremely rare and may be a cause of peripheral ulcerative keratitis. [ncbi.nlm.nih.gov]

• Nausea

  […] keratitis  Cogan’s Syndrome Typical Cogan's syndrome is strictly defined as nonsyphilitic, noninfectious IK associated with vestibuloauditory disease manifested by a sudden, usually bilateral onset of tinnitus, sensorineural hearing loss, vertigo, nausea [slideshare.net]

  […] administration are required. 8, 36, 39, 40 Valacyclovir, another nucleoside analog, has improved bioavailability, and thus it has reduced frequency of administration and can lead to better patient adherence. 41 Both acyclovir and valacyclovir can cause nausea [dovepress.com]

• Erythema

  There was diffuse erythema with itching on face before the onset of eye discomforts. Microbiological culture of materials from both corneas revealed significant growth of Morganella morganii. [ncbi.nlm.nih.gov]

  […] swelling, conjunctival haemorrhage, corneal staining, ocular discomfort, abnormal sensation in eye, visual acuity reduced, visual disturbance, vision blurred, dry eye, eye pruritus, conjunctivitis allergic, lacrimation increased, eyelid irritation, erythema [da.glosbe.com]

  Corneal anesthesia may be present initially, minimizing pain; however, a foreign body sensation and erythema with tearing are frequently present. Slit-lamp exam reveals a classic dendritic lesion that stains with fluorescein dye. [infectiousdiseaseadvisor.com]

  Erythema multiforme after use of topical sulfacetamide. Am J Ophthalmol. 1985 Apr 15. 99(4):465-8. [Medline]. Goldstein MH, Kowalski RP, Gordon YJ. Emerging fluoroquinolone resistance in bacterial keratitis: a 5-year review. [emedicine.medscape.com]

  발의 손톱 영양장애, 홍반(erythema), 각화(scaling) Figure 4. 귓불에 다발성 비립종. Figure 5. [cdc.go.kr]

• Photophobia

  Symptoms include irritation, photophobia, tearing, reduced corneal sensation and blurred vision if the central cornea is involved. [medical-dictionary.thefreedictionary.com]

  […] rash/dermatitis, entropion, facial weakness, facial droop, tiredness, visual disturbance, blurring of vision da Den fælles markedsordning for olivenolie og spiseoliven * (afstemning en Eye disorders Common: conjunctivitis, corneal opacity, keratitis, photophobia [da.glosbe.com]

  Symptoms: photophobia, epiphora (overflow of the tears), feeling of an alien object in the eye, blepharospasm, neuralgic pain, decline of vision. [optometry-today.com]

  If the cornea is involved, early symptoms include foreign body sensation, lacrimation, photophobia, and conjunctival hyperemia. [msdmanuals.com]

• Blurred Vision

  Abstract A 36-year-old HIV-positive man presented with symptoms of redness, blurred vision and foreign body sensation in his right eye for 3 months. [ncbi.nlm.nih.gov]

  Definition of the keratitis are inflammation of the cornea causing watery painful eyes and blurred vision ▲ [meaningin.com]

  […] en Blepharitis, Conjunctivitis, Dry eye, Eye irritation Blurred vision, Cataract, Colour blindness (colour vision deficiencies), Contact lens intolerance, Corneal opacity, Decreased night vision, Keratitis, Papilloedema (as sign of benign intracranial [da.glosbe.com]

  Keratitis is an inflammation or irritation of the cornea (the transparent membrane covering the iris and pupil) characterized by typical symptoms of red eye, foreign body sensation, pain, sensitivity to light, watery eyes, and blurred vision. [hopkinsmedicine.org]

• Dry Eyes

  In this article we will focus specifically on keratitis as it relates to dry eye. In terms of dry eye, clinically evident signs and symptoms can be the result of a variety of causes. [healio.com]

  The most common are: Dry eye: dry eye can cause corneal lesions. The lesions are usually superficial in the form of small spots that primarily affect the middle and lower parts of the cornea. [imo.es]

  (American Academy of Ophthalmology) Dry Eye Disease and Microbial Keratitis: Is There a Connection? – Study regarding the connection between dry eye disease and microbial keratitis. [whatisdryeye.com]

  INTERVENTIONS: All patients (3 women, aged 46, 59, and 84 years) had several years of dry-eye disease history and recurrent keratitis despite having used maximal dose topical therapies including artificial tear substitutes, topical vitamin A, and cyclosporine [ncbi.nlm.nih.gov]

  Patients with a history of keratitis, ulcerative keratitis or severe dry eye may be particularly at risk. [gov.uk]

• Eye Pain

  […] disturbance, vision blurred, dry eye, eye pruritus, conjunctivitis allergic, lacrimation increased, eyelid irritation, erythema of eyelid, blepharitis, asthenopia, growth of eyelashes en Eye disorders Common: eye pain, eye irritation, dry eye, abnormal [da.glosbe.com]

  Keratitis or corneal ulcer signs and symptoms include: Red eye; Eye pain; Tearing and/or discharge from your eye; Pain or irritation that makes opening your eyelid difficult; Burning, itchy or gritty feeling in your eye; Swelling around the eye; A feeling [aao.org]

  Types of bacteria that commonly cause bacterial keratitis include: Pseudomonas aeruginosa Staphylococcus aureus Symptoms of bacterial keratitis include: Eye pain Eye redness Blurred vision Sensitivity to light Excessive tearing Eye discharge If you experience [cdc.gov]

  Red eye Eye pain Feeling that something is in your eye Watery eye Blurred vision Sensitivity to light Swelling of the eyelid How is keratitis diagnosed? Your healthcare provider will ask about your symptoms and when they started. [drugs.com]

  […] lacrimation light sensitivity blurred vision eye pain and/or red eye should be referred promptly to an ophthalmology specialist if a diagnosis of ulcerative keratitis is confirmed, treatment with the EGFR inhibitor should be interrupted or discontinued [gov.uk]

• Foreign Body Sensation

  OUTCOMES: RGTA treatment led to a rapid and marked decrease of ocular pain, burning, irritation, foreign body sensation, and improvement of visual acuity. Total diffuse keratitis healing occurred after several months of treatment. [ncbi.nlm.nih.gov]

  If the cornea is involved, early symptoms include foreign body sensation, lacrimation, photophobia, and conjunctival hyperemia. [msdmanuals.com]

• Prostatic Disease

  Patients on antiandrogenic therapy for prostate disease also have increased viscosity of meibum, decreased tear breakup time (TBUT), and increased tear film debris, all of which indicate a deficient or abnormal tear film. [emedicine.medscape.com]

A preliminary physical examination followed by careful study of the signs and symptoms should be carried out. In addition, the following tests can be employed for diagnosing keratitis [8].

• Eye examination: The eyes should be examined for measuring visual acuity by using the standardized eye charts. Even though the individuals will experience some form of discomfort while opening the eyes for examination, such a type of test is very important and should be performed.
• Penlight examination: Using a penlight, the size and pupil reaction should be measured.
• Slit lamp examination: In this test, the eyes are examined using an instrument known as slit lamp. This instrument illuminates the eye to evaluate the character and extent of keratitis as well as effect on the neighboring areas of the eye.
• Laboratory studies: In this test, sample of the tear or corneal cells are studied for the cause of keratitis. This helps in designing an appropriate treatment plan for the condition.

• The type of treatment employed largely depends on the type of keratitis that has set in. Treatment methods are be different for infectious and non-infectious type of keratitis. 
• If infections are the cause of keratitis, then eye drops should be administered based on the type of organism involved. In case of bacterial infections, antibacterial drops should be advised and if viral agents are the cause, then antiviral drops along with oral medications should be administered [9] [10].
• In cases, when keratitis is caused by the parasite acanthamoeba, antibacterial drops may be of little help. In severe cases, corneal transplant may be required. This is so because such type of infections get difficult to treat through medications and eye drops.
• Individuals suffering from non-infectious keratitis require a 24-hour eye patch and eye drops if contact lenses are the source of cause.

If the condition is diagnosed in early stages and appropriate treatment is given, infections can be treated and onset of vision loss can be prevented. Failure to do so can lead to permanent scarring and long term vision loss. Severe forms of infection can also cause perforation into the cornea leading to loss of the eye.

There are several factors that trigger an attack of keratitis. These include the following:

• Injury: Injury to the eye can pave way for the bacteria and other organisms to gain entry causing infection. In addition, if an object penetrates the cornea or scratches the surface, the resultant irritation can favor the development of keratitis [2].
• Contact lenses: Using contaminated contact lenses for prolonged duration can contaminate the cornea of the eye causing keratitis [3].
• Infectious agents: Various viruses such as herpes simplex virus and herpes zoster virus can also favor inflammation of the cornea. In addition, Chlamydia infection can also lead to keratitis.
• Contaminated water: Various types of chemicals contained in water can irritate the corneal epithelium favoring the development of keratitis.

It has been estimated that about 25,000 individuals in US develop the condition of bacterial keratitis each year. Countries which are less industrialized have fewer cases of infectious keratitis owing to fact that there are less numbers of contact lens users. Severe inflammation of the cornea due to keratitis can be a cause of significant morbidity amongst the affected population [4].

For infection to occur or for the micro organisms to gain entry into the corneal layer, there must be some kind of physical breakdown of the epithelial layer of the cornea. Such an activity paves way for development of keratitis. An injury to the eye, which causes tear in intact film of corneal epithelium favors the entry of microorganisms where they proliferate and may cause ulceration [5].

In the initial stages of the disease, the site of injury and infection undergoes swelling and necrosis. Contact lenses when worn for prolonged duration can cause the corneal epithelium to become vulnerable to attack by bacterial or viral agents [6].

Individuals wearing contact lenses should carefully clean and disinfect their lenses prior to using them every day. Such a habit prevents the development of keratitis. In addition, taking precautionary measures while suffering from viral outbreaks also goes a long way in preventing the onset of keratitis.

Inflammation and pain in the cornea is known is keratitis. Infections and injuries to the eye along with underlying disease conditions can cause keratitis. Mild to moderate cases of keratitis can be easily treated; however, if the condition is left untreated, there can be permanent loss of vision. Individuals suffering from keratitis can experience itchiness in the eyes each time they blink. There are several forms of keratitis depending on the causative factor. Infectious type of keratitis is caused due to bacteria, viruses and fungi. The non-infectious variety is caused due to injury or underlying disease conditions [1].

Keratitis is a condition, wherein there is inflammation of the cornea of the eye. Infections, physical injury and underlying disease conditions are the cause of keratitis. Individuals wearing contact lenses for prolonged duration are at an increased risk of developing the condition. Affected individuals suffer from redness of the eyes accompanied by pain and irritation. There is increased discharge from the affected eye and blurring of vision. Individuals often experience difficulty in opening their eyes due to pain and irritation.

The treatment depends on the cause of keratitis. If bacterial infections are the cause, then antibiotics drops along with medications form the basis of treatment. If parasitic infections are the cause, then corneal transplant may be required. For contact lens wearer, 24-hour eye patch is required.

1. Forster RK. Conrad Berens Lecture. The management of infectious keratitis as we approach the 21st century. CLAO J 1998; 24:175.
2. Goldstein MH, Kowalski RP, Gordon YJ. Emerging fluoroquinolone resistance in bacterial keratitis: a 5-year review. Ophthalmology. Jul 1999;106(7):1313-8.
3. Liesegang TJ. Contact lens-related microbial keratitis: Part I: Epidemiology. Cornea 1997; 16:125.
4. Dart JK. Eye disease at a community health centre. Br Med J (Clin Res Ed) 1986; 293:1477.
5. Hirst LW, Smiddy WE, Stark WJ. Corneal perforations. Changing methods of treatment, 1960--1980.Ophthalmology. Jun 1982;89(6):630-5.
6. Dart JK, Radford CF, Minassian D, et al. Risk factors for microbial keratitis with contemporary contact lenses: a case-control study. Ophthalmology 2008; 115:1647.
7. Leibowitz HM. The red eye. N Engl J Med 2000; 343:345.
8. Varma R, eds. Cornea/external diseases. Essentials of Eye Care: The Johns Hopkins Wilmer Handbook. Lippincott Williams & Wilkins;1997:152-203.
9. Stern GA, Schemmer GB, Farber RD. Effect of topical antibiotic solutions on corneal epithelial wound healing. Arch Ophthalmol. Apr 1983;101(4):644-7.
10. Ray KJ, Srinivasan M, Mascarenhas J, et al. Early addition of topical corticosteroids in the treatment of bacterial keratitis. JAMA Ophthalmol 2014; 132:737.