Acanthamoeba Keratitis Causes Symptoms and Treatment

At first glance, the eye may seem far removed from the risks posed by microorganisms found in the environment. However, certain microscopic organisms can reach the cornea and cause severe inflammation that may threaten vision. One of the most notable conditions is Acanthamoeba keratitis, a relatively rare eye infection characterized by severe symptoms and diagnostic challenges. Delayed diagnosis can lead to serious and potentially permanent complications affecting the cornea.Acanthamoeba naturally exists in water, soil, and dust and can reach the eye under certain circumstances, particularly among contact lens wearers who expose their lenses to water or fail to follow proper hygiene and lens-care practices. The infection often begins with seemingly mild symptoms, such as eye redness, excessive tearing, and a sensation of having a foreign body in the eye. However, these symptoms may progress to severe eye pain, increased sensitivity to light, blurred vision, and damage to the corneal tissues.The danger of Acanthamoeba keratitis lies in the fact that its early symptoms can resemble those of other types of keratitis, making early diagnosis a significant challenge. In addition, some forms of Acanthamoeba are highly resistant to treatment, which can make the treatment journey lengthy and complex. In advanced cases, surgical intervention may be required to preserve the eye and help restore vision.Therefore, understanding this condition involves more than simply knowing its causes and symptoms. It also requires understanding its risk factors, modern diagnostic methods, medical treatment options, the role of surgery in severe cases, and the importance of prevention and proper contact lens care.In this Dalili Medical guide, we provide a comprehensive overview of Acanthamoeba keratitis, covering everything from the initial infection through diagnosis, treatment, and potential complications, with a particular focus on the importance of early detection before the condition causes permanent damage to the cornea or vision.

What Is Acanthamoeba Keratitis?

Acanthamoeba keratitis is a rare infection of the cornea caused by a free-living amoeba known as Acanthamoeba. The infection can be severe and may affect vision if it is not diagnosed and treated early.

Is Acanthamoeba Keratitis Dangerous?

Yes. Acanthamoeba keratitis can be serious, particularly when diagnosis is delayed or the infection does not respond adequately to treatment. In advanced cases, it may lead to corneal ulceration, thinning, or perforation and may leave a corneal scar that affects vision.

Is Acanthamoeba Keratitis Contagious?

Acanthamoeba keratitis is not usually transmitted from person to person. The infection occurs when Acanthamoeba found in the environment, particularly in water or soil, reaches the cornea under conditions that allow the organism to cause infection.

What Is the Relationship Between Contact Lenses and Acanthamoeba Keratitis?

Contact lens use is one of the most important risk factors for Acanthamoeba keratitis, particularly when lenses are not used or cared for properly. Risky practices include sleeping while wearing contact lenses, swimming or showering with them, rinsing them with tap water, or failing to disinfect and store them properly.

Can Someone Develop Acanthamoeba Keratitis Without Wearing Contact Lenses?

Yes. Acanthamoeba keratitis can occur in people who do not wear contact lenses, although this is less common. It may be associated with exposure of the eye to water or soil or with an injury or scratch to the surface of the cornea.

Can Swimming Cause Acanthamoeba Keratitis?

Yes. Exposure of the eyes to contaminated water during swimming may increase the risk of infection. The risk is particularly higher when contact lenses are worn while swimming.

Can Tap Water Cause Acanthamoeba Keratitis?

Tap water may be a potential source of exposure to Acanthamoeba. Therefore, contact lens wearers are advised not to use tap water to clean their contact lenses or lens cases and not to rinse the lenses with tap water.

Does Severe Eye Pain Necessarily Mean Acanthamoeba Keratitis?

No. Severe eye pain can occur with many different corneal and eye conditions. Therefore, Acanthamoeba keratitis cannot be diagnosed based on pain alone.

Can Acanthamoeba Keratitis Improve on Its Own?

You should not wait for spontaneous improvement if Acanthamoeba keratitis is suspected. The infection can progress and cause permanent corneal damage. Suspected cases therefore require prompt evaluation by an ophthalmologist.

How Is Acanthamoeba Keratitis Diagnosed?

Diagnosis is based on a combination of factors, including:

Medical history and contact lens habits.
Eye examination using a slit lamp.
Corneal scraping.
Microscopic examination.
Microbial culture.
Molecular tests such as PCR when appropriate.
In-vivo confocal microscopy.

Diagnosis does not usually rely on a single test alone.

Can Acanthamoeba Keratitis Be Mistaken for Bacterial Keratitis?

Yes. The symptoms and clinical findings can be similar during the early stages, which may result in delays in diagnosing Acanthamoeba keratitis. Coinfection with Acanthamoeba and other pathogens can also occur.

Can Acanthamoeba Keratitis Be Prevented?

The risk of infection can be significantly reduced by following proper contact lens care practices. Important preventive measures include:

Wash and thoroughly dry your hands before handling contact lenses.
Do not sleep while wearing contact lenses unless specifically advised to do so by your eye doctor.
Do not swim or shower while wearing contact lenses.
Never rinse contact lenses or their storage cases with tap water.
Use only the contact lens solution recommended for your lenses.
Do not reuse old contact lens solution.
Clean the contact lens case properly and replace it regularly.
Follow the replacement schedule for your contact lenses as recommended by the manufacturer or your eye doctor.

Causes of Acanthamoeba Keratitis

1. Contact Lens Use — The Most Important Risk Factor

A large proportion of Acanthamoeba keratitis cases occur in contact lens wearers. This does not mean that wearing contact lenses itself causes the infection. Rather, the risk increases when contact lenses are used incorrectly or when proper hygiene and disinfection practices are not followed.

Some of the practices that may increase the risk of infection include:

Sleeping while wearing contact lenses.
Wearing contact lenses for longer than the recommended period.
Failing to clean and disinfect contact lenses properly.
Using contact lenses beyond their recommended replacement period.
Failing to wash and thoroughly dry hands before handling contact lenses.
Reusing old contact lens solution instead of discarding it and replacing it with fresh solution.
Washing or rinsing contact lenses with tap water.
Storing contact lenses in water.
Using homemade or non-sterile solutions to clean contact lenses.
Neglecting to clean the contact lens case or failing to replace it regularly.

2. Exposure to Water While Wearing Contact Lenses

Exposure of contact lenses to water is an important risk factor for Acanthamoeba keratitis because Acanthamoeba can be present in various water sources, including:

Tap water.
Well water.
Lakes and rivers.
Swimming pools.
Hot tubs.
Other potentially contaminated water sources.

For this reason, it is recommended to avoid showering, swimming, or using hot tubs while wearing contact lenses.

The risk occurs because a contact lens may trap water and microorganisms close to the surface of the cornea, increasing the chance that Acanthamoeba can reach the eye. In addition, some types of soft contact lenses can absorb water, potentially changing their properties or causing them to adhere more closely to the corneal surface. This may lead to irritation or damage to the corneal surface and increase susceptibility to infection.

3. Corneal Scratches and Injuries

Any damage to the surface of the cornea can potentially provide an entry point for Acanthamoeba, even if the scratch is minor.

Corneal injuries may occur as a result of:

Scratching the eye with fingernails.
Getting a foreign object in the eye.
Rubbing the eye forcefully.
Sustaining an injury during work or sports.
Using contact lenses in a way that causes friction or irritation to the cornea.
Wearing contaminated contact lenses.
Severe dry eye or persistent irritation that compromises the integrity of the corneal surface.

The risk may be higher when a corneal scratch or surface damage occurs together with exposure to water or an environmental source containing Acanthamoeba.

4. Poor Cleaning of Contact Lenses and Their Storage Case

Contact lenses and their storage cases can become sources of microorganism buildup if they are not properly cleaned, disinfected, and maintained.

Common mistakes include:

Topping off old solution in the lens case with fresh solution instead of completely discarding the old solution.
Using tap water to clean the contact lens case.
Storing contact lenses in water.
Using a solution that is not specifically designed for contact lenses or is not sterile.
Handling contact lenses with unclean hands.
Neglecting to clean the contact lens case or failing to replace it at the recommended intervals.

Certain improper contact lens care practices have been associated with an increased risk of Acanthamoeba keratitis.

5. Cosmetic Contact Lenses and Orthokeratology Lenses

The use of certain types of lenses, including cosmetic contact lenses and orthokeratology (Ortho-K) lenses, may be associated with an increased risk of infection under certain circumstances, particularly when proper hygiene, disinfection, and usage instructions are not followed.

The risk may be further increased when these lenses are exposed to water, worn for extended periods, or stored improperly.

6. Environmental Exposure to Acanthamoeba

Acanthamoeba is a microorganism that is widely distributed in the environment and can be found in various places, including:

Water.
Soil.
Dust.
Certain moist environments.

Symptoms of Acanthamoeba Keratitis

1. Severe Eye Pain

Eye pain is one of the most prominent symptoms of Acanthamoeba keratitis. The pain may be severe and deep and can persist continuously or occur in intermittent episodes.

Patients may describe the pain as:

Burning or throbbing.
Stinging or stabbing.
Persistent or progressively worsening.
Severe enough to interfere with sleep and daily activities.

2. Eye Redness

Eye redness occurs as a result of inflammation and increased congestion of the blood vessels surrounding the cornea.

The redness may be:

More noticeable around the cornea.
Diffuse throughout the white part of the eye.
Accompanied by pain.
Associated with severe sensitivity to light.

Redness may become more pronounced as the inflammation and severity of the infection increase.

3. Severe Sensitivity to Light — Photophobia

Sensitivity to light is a common symptom of Acanthamoeba keratitis. Patients may feel that normal levels of light have become uncomfortable or painful.

They may need to:

Close their eyes frequently.
Avoid brightly lit environments.
Wear sunglasses even indoors.

Sensitivity to light generally becomes more pronounced as corneal inflammation increases.

4. Increased Tearing

Inflammation of the cornea and irritation of the eye surface can stimulate excessive tear production.

Tearing may be:

Continuous or recurrent.
Accompanied by burning and irritation.
More noticeable when opening the eye.
Increased when exposed to light or air.

Excessive tearing is a natural protective response as the eye attempts to protect the corneal surface from irritation and inflammation.

5. Foreign Body Sensation in the Eye

Patients may feel as though something is stuck inside the eye, even when there is no actual foreign object present.

This sensation may be described as:

Feeling as though there is sand in the eye.
Feeling as though there is a grain of dust in the eye.
A sensation that something is scratching the eye with every blink.
Feeling as though an object is trapped underneath the eyelid.

6. Blurred Vision or Reduced Visual Acuity

As the inflammation progresses, the transparency of the cornea may be affected, leading to visual disturbances.

Patients may notice:

Blurred or hazy vision.
A gradual reduction in visual acuity.
Difficulty seeing details clearly.
Increased blurring when looking at light sources.

7. Seeing Halos Around Light Sources

Patients may see circles or halos around light sources, particularly:

Lamps.
Car headlights at night.
Device screens.
Bright light sources.

8. Corneal Swelling and Loss of Transparency

As inflammation progresses, the cornea may become swollen and lose some of its normal transparency.

During an eye examination, an ophthalmologist may observe:

Corneal edema or swelling.
Corneal opacities.
Inflammatory infiltrates.
Abnormalities of the corneal surface.
Changes in the deeper corneal layers in advanced cases.

Medical Treatment for Acanthamoeba Keratitis

1. First-Line Treatment: Biguanides

Biguanides are among the most important topical medications used to treat Acanthamoeba keratitis. The main agents include polyhexamethylene biguanide (PHMB) and chlorhexidine.

Polyhexamethylene Biguanide (PHMB)

PHMB is one of the main topical anti-Acanthamoeba medications and is included in a number of treatment protocols.

Commonly used concentrations include:

0.02%, which is frequently used in many treatment protocols.
Higher concentrations may be used in certain cases and specialized centers, depending on the corneal specialist's assessment and the formulation being used.

Treatment is usually started with a very intensive dosing regimen. Drops may be administered at frequent intervals during the initial phase and then gradually reduced as the cornea improves and inflammation becomes stable.

The prolonged duration of treatment is partly due to the need to control not only the trophozoite stage of Acanthamoeba but also its cysts, which are considerably more resistant to treatment.

Chlorhexidine

Chlorhexidine is another important treatment option for Acanthamoeba keratitis and is used in some treatment protocols at a concentration of 0.02%.

A physician may use chlorhexidine instead of PHMB or, in certain situations, combine the two medications, particularly in severe or treatment-resistant cases.

However, combining topical medications may increase the risk of corneal surface toxicity. Therefore, the appropriate concentration, dosage, and frequency of administration should be determined under the supervision of a corneal specialist.

2. Adding Diamidines

A physician may add a medication from the diamidines group to a biguanide, particularly in moderate or severe cases.

Important examples include:

Propamidine Isethionate

Propamidine isethionate is used in some treatment protocols at a concentration of 0.1%.

Hexamidine

Hexamidine 0.1% may be used as another option in certain cases and specialized centers.

A traditional treatment regimen may therefore involve:

PHMB or chlorhexidine + propamidine or hexamidine

The goal of combining these medications is to provide anti-Acanthamoeba activity through different pharmacological mechanisms.

However, there is no single treatment regimen that is appropriate for every patient. Some patients may respond well to treatment with a biguanide alone, whereas more severe cases may require combination therapy.

3. How Intensive Is Treatment During the Early Stage?

Treatment is generally very intensive during the initial phase, particularly when the diagnosis has been confirmed or there is a high level of suspicion for Acanthamoeba keratitis.

A corneal specialist may prescribe anti-Acanthamoeba eye drops at very frequent intervals during the first few days and then gradually reduce the frequency as signs of improvement appear.

The physician may assess treatment response based on several factors, including:

Reduced severity of pain.
No further progression of corneal infiltrates.
Improvement in inflammation.
Beginning of epithelial defect healing.
Improvement in the appearance of the cornea.
Stabilization or improvement of vision.

Surgical Treatment for Acanthamoeba Keratitis: Types of Surgery and How They Are Performed

When Is Surgery Needed?

Surgical intervention may be considered when one or more of the following conditions are present:

Severe inflammation that does not respond adequately to anti-Acanthamoeba treatment.
An advanced or progressively enlarging corneal ulcer.
Severe corneal thinning.
A high risk of corneal perforation.
Actual corneal perforation.
Infection extending into the deep stroma.
Extensive spread of infection within the cornea.
Continued deterioration of the cornea despite intensive treatment.
A large corneal scar or opacity remaining after the infection has been controlled and significantly affecting vision.

Therapeutic surgery is primarily used in advanced or treatment-resistant cases. In general, elective visual rehabilitation surgery is preferably delayed until the infection has been controlled and the eye has become stable.

1. Corneal Debridement and Removal of Infected Tissue

Therapeutic Epithelial Debridement / Corneal Debridement

Corneal debridement or removal of infected tissue may be used in selected cases. This procedure is not the same as a corneal transplant.

How Is the Procedure Performed?

The ophthalmologist removes unhealthy superficial tissue from the cornea. This may include:

Infected or damaged epithelium.
Dead or nonviable tissue.
Secretions and accumulated material on the corneal surface.
Some superficial infected tissue, depending on the depth of the infection.

Anti-Acanthamoeba treatment is then continued intensively.

What Is the Purpose of Debridement?

This procedure may help to:

Remove some of the organisms present in superficial tissues.
Improve penetration of topical medications into the cornea.
Remove damaged epithelium that may interfere with healing of the corneal surface.
Obtain an appropriate specimen for microscopic examination, culture, and PCR testing.

However, debridement alone generally does not eliminate Acanthamoeba located within the corneal stroma. Therefore, it should not be considered a substitute for medical treatment.

2. Therapeutic Phototherapeutic Keratectomy (PTK)

Phototherapeutic Keratectomy (PTK) is a procedure that uses an excimer laser to remove selected superficial layers of the cornea.

It is not routinely used in all cases of Acanthamoeba keratitis. Instead, it may be considered in selected cases when the infection is relatively superficial, limited in depth, and has not responded adequately to medical treatment.

When Can PTK Be Considered?

PTK may be appropriate when the infection is:

Relatively superficial.
Limited to the anterior layers of the cornea.
Resistant to medical treatment.
Not associated with severe corneal thinning.
Not associated with an imminent risk of perforation.

How Is PTK Performed?

In general, the procedure involves:

Applying topical anesthesia to the eye.
Removing the damaged epithelium.
Using an excimer laser to remove a carefully measured amount of superficial stromal tissue.
Applying appropriate postoperative treatment.
Closely monitoring corneal healing and controlling the infection.

The basic concept is to remove superficial infected or damaged tissue, which may also help improve the penetration of topical medications into the affected tissues.

What Are the Limitations of PTK?

If Acanthamoeba is present in the deep stroma, PTK is generally unlikely to be sufficient. Removing a large amount of stromal tissue may also result in dangerous corneal thinning.

Therefore, PTK is a selective treatment option rather than a routine treatment for all cases of Acanthamoeba keratitis.

3. Deep Anterior Lamellar Keratoplasty (DALK)

Deep Anterior Lamellar Keratoplasty (DALK) is an important surgical option when the infection is confined to the anterior or mid-stroma while the deeper corneal layers remain healthy.

When the primary goal of the procedure is to remove active infection, it is referred to as:

Therapeutic Deep Anterior Lamellar Keratoplasty (TDALK)

In other cases, lamellar keratoplasty may be performed for visual rehabilitation after the infection has healed but a corneal scar or opacity remains and significantly affects vision.

Understanding the DALK Procedure

The cornea consists primarily of several layers arranged from front to back:

Epithelium
↓
Bowman's layer
↓
Stroma
↓
Descemet's membrane
↓
Corneal endothelium

During DALK, the affected epithelium and infected stromal tissue are removed while attempting to preserve the deeper layers, particularly Descemet's membrane and the corneal endothelium.

Why Is DALK Useful?

DALK allows the surgeon to remove the affected portion of the cornea while preserving the patient's own corneal endothelium. This may reduce some of the risks associated with replacing the entire thickness of the cornea.

4. How Is DALK Generally Performed?

The exact surgical technique varies depending on the surgeon's approach and the condition of the cornea. However, the main stages can generally be summarized as follows:

Stage 1: Determining the Depth of the Infection

The surgeon carefully evaluates the cornea using:

Slit-lamp examination.
Anterior Segment Optical Coherence Tomography (AS-OCT), when indicated.
In-vivo confocal microscopy in selected cases.

The goal is to determine whether the infection extends into deeper corneal layers that could make DALK unsuitable.

Stage 2: Removal of Infected Tissue

The damaged epithelium is removed, followed by gradual and carefully controlled removal of the infected stroma.

Stage 3: Reaching a Healthy Deep Plane

The surgeon attempts to reach a healthy deep corneal plane while preserving Descemet's membrane and the corneal endothelium whenever possible.

Stage 4: Preparation of the Donor Tissue

Suitable lamellar corneal tissue from a donor is prepared to match the portion removed from the patient's cornea.

Stage 5: Placement of the Donor Tissue

The donor tissue is placed over the remaining deep corneal layer of the patient's eye.

Stage 6: Securing the Graft

The graft is secured using fine surgical sutures or another appropriate technique depending on the surgical method used.

Stage 7: Monitoring the Infection

Close postoperative monitoring continues after surgery. Anti-Acanthamoeba treatment may also be continued depending on the activity of the infection and the risk of recurrence.

It is important to emphasize that undergoing DALK does not automatically mean that anti-Acanthamoeba treatment can be discontinued.

5. When Is DALK Not Appropriate?

DALK may not be suitable when the infection extends into the deeper layers of the cornea, such as:

The very deep stroma.
Descemet's membrane.
Extensive or full-thickness corneal involvement.

In these situations, leaving the deeper layers in place may result in a risk of residual infection.

In such cases, the more appropriate option may be:

Therapeutic Penetrating Keratoplasty (TPK)

The depth of infection is one of the most important factors guiding the surgeon's choice between DALK and TPK.

6. Therapeutic Penetrating Keratoplasty (TPK)

Therapeutic Penetrating Keratoplasty (TPK) is one of the most important surgical procedures for advanced cases of Acanthamoeba keratitis.

It is a full-thickness corneal transplant primarily intended to remove infected corneal tissue, control the infection, and preserve the structural integrity of the eye.

When Is TPK Used?

TPK may be performed when there is:

Deep infection.
Extensive infection.
Failure to respond adequately to intensive medical treatment.
Severe corneal thinning.
A high risk of perforation.
Actual corneal perforation.

At this stage, the primary goal is not immediate visual improvement but rather controlling the infection and preserving the eye.

7. How Is TPK Generally Performed?

The exact details vary depending on the individual case, but the main steps generally include:

1. Anesthesia

The procedure may be performed under local or general anesthesia, depending on the patient's condition and the surgical team's assessment.

2. Identifying the Infected Area

The surgeon identifies the ulcer, infiltrates, and unhealthy tissue and determines the appropriate size of the corneal area that needs to be removed.

3. Removal of the Infected Cornea

A section of the cornea is removed through its full thickness. This is the key feature distinguishing TPK from DALK.

4. Removal of Infected Tissue

The surgeon aims to remove as much infected tissue as possible while avoiding unnecessary removal of healthy tissue.

5. Placement of the Donor Cornea

A suitable donor corneal button is placed in the area from which the infected cornea was removed.

6. Securing the Graft

The graft is secured with fine surgical sutures. Depending on the case and surgical technique, interrupted or continuous sutures may be used.

7. Examination of the Excised Cornea

The removed corneal tissue should be sent to the laboratory for evaluation for:

Acanthamoeba cysts.
Trophozoites.
Bacteria.
Fungi.
Other infectious organisms.
The extent of infection within the cornea.

8. Postoperative Treatment and Follow-Up

Close medical follow-up continues after surgery, and anti-Acanthamoeba treatment may be continued according to the corneal specialist's assessment.

8. What Happens If a Corneal Perforation Occurs?

Corneal Perforation

Corneal perforation is one of the most serious complications of Acanthamoeba keratitis. It may require urgent intervention to preserve the structural integrity of the eye and prevent loss of its contents.

The choice of procedure depends on:

The size of the perforation.
Its location.
Its depth.
The condition of the surrounding tissue.
The activity of the infection.

Treatment options may include tissue adhesive, corneal patch grafting, or therapeutic keratoplasty.

9. Tissue Adhesive

Tissue adhesive may be used for certain small corneal perforations or areas of severe thinning that are at risk of perforation.

How Is Tissue Adhesive Used?

In general:

The affected area is cleaned.
The area is appropriately prepared.
A precise amount of adhesive is applied to the site of leakage.
A protective measure, such as a bandage contact lens, may be used depending on the ophthalmologist's assessment.
Anti-Acanthamoeba treatment and close monitoring are continued.

What Is the Purpose of the Adhesive?

The adhesive does not eliminate Acanthamoeba. Its primary purposes are to:

Seal the leak.
Maintain the structural integrity of the eye.
Prevent progression of the perforation.
Provide a temporary or appropriate solution in selected cases.

Large perforations or perforations associated with deep infection may require therapeutic corneal transplantation.

10. Amniotic Membrane Transplantation (AMT)

Amniotic Membrane Transplantation (AMT) may be used in selected cases involving significant damage to the corneal surface or delayed epithelial healing.

It may be considered when there is:

Extensive epithelial loss.
A persistent corneal epithelial defect.
Delayed healing of the corneal surface.
Severe superficial inflammation.
Certain selected cases of corneal thinning.

What Are Its Benefits?

The amniotic membrane may help to:

Provide a supportive surface for epithelial regeneration.
Promote healing of the corneal surface.
Reduce certain inflammatory processes.
Limit some forms of fibrosis and scarring.

However, amniotic membrane transplantation is not a treatment for active Acanthamoeba infection and does not replace anti-Acanthamoeba therapy.

11. Conjunctival Flap

In some chronic or complicated cases, a portion of the conjunctiva may be used to cover the damaged area of the cornea.

Goals of a Conjunctival Flap

A conjunctival flap may aim to:

Protect the cornea.
Support tissue healing.
Reduce further loss of corneal tissue.
Provide coverage in selected cases where maintaining corneal integrity is difficult.

However, there is an important limitation: covering the cornea may make it more difficult to monitor ongoing infection within the corneal tissue.

Therefore, a conjunctival flap is not a routine option for every case of Acanthamoeba keratitis and is reserved for selected cases determined by a corneal specialist.

12. Optical Corneal Transplantation

Optical Penetrating Keratoplasty (Optical PKP) differs fundamentally from therapeutic corneal transplantation.

In TPK, the primary goal is to remove the infection and preserve the eye.

In Optical PKP, the infection has already been eliminated, but a visual problem remains because of a dense corneal scar or opacity.

Example

A patient may progress through the following stages:

Acanthamoeba keratitis
↓
Anti-Acanthamoeba treatment
↓
Eradication of active infection
↓
Resolution and stabilization of the eye
↓
Persistent dense central corneal scar
↓
Continued visual impairment

In this situation, optical corneal transplantation may be considered to improve vision.

Optical keratoplasty is generally avoided while active infection is still present. Controlling the infection and ensuring that the eye has become stable are important factors for surgical success and for reducing the risk of recurrent infection or graft failure.