OVERVIEW

What is keratitis?

The cornea is a transparent tissue of certain thickness located on the surface of the black part of our eyes. Under a microscope, it is divided into 5 layers of cells.

Inflammation occurring in any layer of the corneal tissue can be referred to as keratitis.

Keratitis may lead to corneal ulcers, so what is a corneal ulcer?

Due to infection, inflammation, burns, or other reasons, when the corneal tissue undergoes necrosis from the outer to the inner layers—that is, from the surface to the deeper layers—it is clinically called a corneal ulcer or ulcerative keratitis.

If an ulcer forms, it indicates that the condition of keratitis has worsened.

SYMPTOMS

What are the symptoms of keratitis?

Keratitis has many symptoms, and they may vary from patient to patient.

Possible symptoms include: eye pain, redness, a feeling of something in the eye, sensitivity to light, tearing, eyelid twitching, blurred vision, increased eye discharge, and more.

Can keratitis affect vision?

Before treatment, keratitis can significantly impair vision.

If the inflammation has been treated with medication, whether keratitis affects vision depends mainly on the severity of the inflammation, whether it occurred in the center or periphery of the cornea, and whether the impact was superficial or deep.

• If the inflammation was superficial and left no scarring after treatment, or if scarring occurred but the affected area was in the peripheral part of the cornea (the outer ring of the black part of the eye), vision may be unaffected or only slightly affected.

• If the inflammation was deep, leaving noticeable scarring after treatment, or if the affected area was in the center of the cornea (the pupil area), vision may be significantly impaired.

• In particularly severe cases, some patients may even require removal of the entire eyeball, resulting in complete vision loss.

What other problems can keratitis cause?

After developing keratitis, the following complications may occur:

• Corneal scarring (the inflammation resolves but leaves scars on the cornea)
• Increased corneal astigmatism (due to an uneven corneal surface after healing, leading to astigmatism or worsening of existing astigmatism)
• Corneal staphyloma (a bulging, purplish-black scar mixed with iris tissue—the brown ring at the junction of the black and white parts of the eye)
• Corneal perforation (a hole in the cornea)
• Prolapse of intraocular contents (due to a hole or extreme thinning of the cornea, causing internal eye structures to protrude)
• Scleritis
• Iridocyclitis
• Inflammation of other eye tissues, such as endophthalmitis.

Later complications may include glaucoma, cataracts, and eyeball atrophy.

CAUSES

What are the causes of keratitis?

Based on etiology, keratitis can be classified into infectious and non-infectious types.

• Infectious keratitis occurs when pathogens infect the cornea, causing inflammation. Common pathogens include bacteria, fungi, and viruses.

• Non-infectious keratitis can have various causes, including autoimmune or nutritional deficiencies.

Additionally, inflammation in other eye structures, whether infectious or non-infectious, may spread to the cornea.

What causes bacterial keratitis?

The cornea has a surface layer of cells called corneal epithelial cells, which maintain corneal integrity like a protective barrier.

If this layer is damaged, the cornea becomes vulnerable to infection.

Therefore, corneal trauma or surgery that damages the epithelium increases the risk of bacterial infection.

Common causes include:

• Corneal abrasions, foreign body removal, or pterygium surgery.

• Pre-existing ocular surface diseases or systemic conditions that weaken immunity, such as dry eye or diabetes.

• Long-term corticosteroid use, contact lens wear, poor eye hygiene (e.g., rubbing eyes with dirty hands), or contaminated eye drops (discard after one month of opening).

• Newborns may acquire infections during delivery.

What causes fungal keratitis?

The main cause is eye injury from agricultural work, such as plant leaves, branches, or dirt. It is more common in tropical/subtropical regions among farmers and outdoor workers.

Other risk factors include:

• Corneal abrasions, foreign body removal, or pterygium surgery.

• Pre-existing ocular surface diseases or systemic conditions like dry eye or diabetes.

• Long-term corticosteroid use, contact lens wear, poor eye hygiene, or contaminated eye drops.

• Newborns may acquire infections during delivery.

What are the characteristics of viral keratitis?

Herpes simplex virus is the most common cause.

It often occurs when immunity is low, such as during colds, fever, or menstruation.

Symptoms may initially be mild, and treatment is more effective than for bacterial/fungal infections, but recurrence is common.

Who is at risk for Acanthamoeba keratitis?

Normally, the corneal surface is intact.

Acanthamoeba, a microorganism, can cause infection when the corneal surface is compromised (e.g., by surgery or injury) and exposed to contaminated water (e.g., swimming or hot springs).

It is more common in contact lens wearers or those with corneal trauma.

What causes ultraviolet keratitis?

Exposure to excessive UV light (e.g., welding without eye protection or snow activities without sunglasses) can cause symptoms like foreign body sensation, redness, tearing, pain, photophobia, burning, and difficulty opening the eyes within hours.

DIAGNOSIS

How is keratitis diagnosed?

Based on symptoms such as eye pain and photophobia, doctors can directly examine the cornea using a slit-lamp microscope in the outpatient clinic, making the diagnosis of keratitis generally straightforward.

However, determining the cause of keratitis requires a thorough understanding of the patient's medical history, careful observation of corneal inflammation characteristics, and sometimes additional tests to aid diagnosis.

What tests are needed for keratitis?

Depending on the condition, the doctor may need to scrape a small sample of inflamed tissue from the affected cornea for microscopic examination. If the specific microbial infection is unclear, laboratory culturing may be required for confirmation.

If the doctor suspects keratitis is caused by systemic diseases, further comprehensive examinations may be necessary.

How is bacterial keratitis diagnosed?

Based on predisposing factors, the speed of progression, and clinical symptoms like eye pain and photophobia, combined with slit-lamp microscopy to assess corneal inflammation, doctors can make a preliminary diagnosis.

Typically, before starting treatments like eye drops, a swab or tool is used to collect ulcerated corneal tissue for bacterial culture testing to identify the specific pathogen.

How is fungal keratitis diagnosed?

Considering predisposing factors (e.g., eye injury from plant leaves), disease progression, and clinical symptoms, doctors examine corneal lesions with a slit-lamp microscope. Before treatment, corneal ulcer tissue is collected for confocal microscopy to detect fungal hyphae, microscopic smear examination, or laboratory fungal culture to confirm the diagnosis.

TREATMENT

How to treat keratitis?

The most basic treatment for keratitis is the use of eye drops or ointments, which act locally on the eyes.

If local treatment fails to control the inflammation, systemic medication such as oral or intravenous administration may be necessary. In severe cases, surgical intervention might even be required.

Overall, treatment methods vary significantly depending on the cause and severity of the condition.

Can keratitis be completely cured?

The prognosis of keratitis varies greatly depending on the cause and severity. It may fully recover or leave some sequelae.

Mild inflammation often responds well to treatment, with better corneal healing and minimal impact on vision. Severe inflammation, however, may persist, causing intense eye pain, poor vision, or even requiring surgical removal of the eyeball in the worst cases.

How to treat bacterial keratitis?

Bacterial keratitis requires immediate antibiotic treatment to kill or inhibit the bacteria, control inflammation, and alleviate symptoms.

If laboratory tests confirm a specific bacterial infection, targeted medications can be used.

Is eye drops alone sufficient for keratitis?

A small number of patients with mild conditions may control the disease with prescribed eye drops alone. However, close monitoring is necessary during treatment. If symptoms like eye pain or photophobia worsen, additional treatments may be needed.

Many patients, however, have severe or rapidly progressing conditions that require more than eye drops, such as subconjunctival injections, oral or intravenous medications, or even anterior chamber injections.

Surgical treatments like corneal ulcer debridement, anterior chamber irrigation, biological membrane coverage, or corneal transplantation may also be necessary.

How to treat fungal keratitis?

Fungal keratitis progresses slowly with mild symptoms, often leading to severe conditions before patients seek medical attention. Symptoms may include slight eye irritation.

Once diagnosed, immediate topical antifungal eye drops are required, sometimes combined with oral or systemic intravenous antifungal therapy.

If the eye is scratched by crop leaves, branches, or dirt, seek ophthalmological care promptly. The risk period can last up to one or two months, as fungal keratitis may develop long after the injury.

Can fungal keratitis be cured?

Most patients delay treatment until the condition worsens, resulting in poorer outcomes.

Even with treatment, multiple medications may not be highly effective against fungi, and prolonged use can cause significant side effects.

Patients with timely and effective treatment, especially those with peripheral or superficial lesions, may recover well with minimal corneal scarring. Severe cases might require corneal debridement, conjunctival flap coverage, or corneal transplantation to preserve the eyeball and some vision. The worst cases may necessitate eyeball removal.

How to treat viral keratitis?

Basic treatment involves antiviral eye drops and ointments. Severe cases may require oral or intravenous medications.

In extreme cases, corneal ulceration or perforation may necessitate surgery.

How to treat Acanthamoeba keratitis?

Use anti-Acanthamoeba eye drops, typically for several months. Additional medications or surgery may be required if necessary.

How to treat ultraviolet keratitis?

Apply epithelial growth-promoting eye drops or gels to accelerate corneal healing.

Since the corneal epithelium is damaged, prophylactic antibiotic eye drops are often used to prevent infection.

For severe pain, oral painkillers may provide temporary relief.

Can ultraviolet keratitis be cured?

It usually heals within days without affecting vision.

However, before full epithelial recovery, secondary infections like bacterial or viral keratitis may occur. Prophylactic antibiotic eye drops are often recommended.

Can corneal ulcers be cured?

The cornea is a transparent tissue with multiple layers. Ulcers cause thinning, and healing results in scar tissue rather than restored transparency.

Corneal ulcers indicate a serious condition requiring close monitoring, often hospitalization. Perforation worsens the prognosis.

Can keratitis patients undergo LASIK for myopia correction?

This refers specifically to LASIK for refractive error correction.

Patients with active keratitis cannot undergo LASIK.

Post-recovery, individual assessments are needed, including corneal thickness checks.

Some patients may qualify for LASIK aimed at repairing corneal scars.

DIET & LIFESTYLE

Can keratitis patients wear contact lenses?

It must be emphasized that the contact lenses referred to here specifically refer to the soft corneal contact lenses available on the market, not the specialized therapeutic contact lenses used in hospitals.

If keratitis has not fully healed, patients should not wear contact lenses on their own.

After keratitis has completely healed, a doctor's evaluation is required. If the surface structure of the eye remains normal and smooth, contact lenses can be worn.

Can keratitis patients donate corneas?

If corneal inflammation is present at the time of intended donation, donation is not possible.

Whether corneas that have previously had keratitis can be donated depends on the specific condition. If the cornea has scars, insufficient endothelial cells, or if the patient had viral keratitis (a type prone to recurrence), donation is not allowed.

Only a few types, such as photokeratitis, which heal completely without leaving traces, do not affect donation.

PREVENTION

How to Prevent Acanthamoeba Keratitis?

When wearing contact lenses, strict hand hygiene must be observed. Wash hands thoroughly with water and soap or hand sanitizer before carefully putting on the lenses to avoid corneal damage. Do not use expired lens care solutions or lenses.

Avoid water activities like swimming while wearing contact lenses or after eye injuries. Maintain good eye hygiene habits daily and avoid rubbing your eyes with dirty hands.

How to Prevent Ultraviolet Keratitis?

Wear protective goggles or masks when welding, viewing UV lamps, or spending extended periods outdoors under intense sunlight, especially during activities in snowy or watery environments.

How to Prevent Keratitis?

Maintain eye hygiene. Avoid using prescription-only eye drops like antibiotics without authorization. Do not rub your eyes with dirty hands, and ensure proper hygiene when wearing contact lenses. Seek prompt medical attention for any eye issues. Effectively manage chronic conditions such as diabetes or dry eye syndrome.