Toxic Anterior Segment Syndrome

Introduction

The eyes are the window to our bodies. We see things through our eyes, without which the quality of life will be significantly affected. Any issue to the eye will itself cause anxiety in us. Eyes are always considered sacred for many known reasons. The eyes are composed of layers from the outer to the inner, namely the cornea, iris, lens, and retina. Between the corneal and iris (the front part of the eyes), a space containing the aqueous humor is called the anterior chamber.

The anterior chamber controls the amount of light entering the eye by closing and opening the pupil. The light enters the cornea, passes through the iris, and then enters the lens from where the light will be directed towards the retina, which creates an image for vision.

In some cases, especially in old age, this lens gets covered by a layer of cataract film, disrupting the vision. This condition will generally need surgical intervention.

There are many more conditions where intraocular surgery, like glaucoma, diabetic retinopathy, retinal tears, detached retinas, etc. There are several postoperative complications of these surgeries, and one of the rare conditions is toxic anterior segment syndrome. It commonly occurs due to using unsterile instruments during surgery and other factors. It presents as inflammation after one to two days of anterior segment surgery. The iris and lens or surgeries involving the iris and lens are termed anterior segment surgery.

What Causes Toxic Anterior Segment Syndrome?

Arriving at the cause of toxic anterior segment syndrome is a non-success even after a thorough examination. Yet few reasons are considered the source and diagnosis revolve around the same.

• Surgical instruments and tubings are not appropriately sterilized (primary cause).

• Flushing the instruments inadequately during surgery.

• Using irrigation solutions containing antibiotics. Levels of preservatives used beyond the tolerable range.

• Metal residue formations.

• Usage of intraocular solutions like balanced salt solutions.

• Autoclave steam impurities.

• Denatured viscoelastic devices.

• Intraocular lens.

How to Differentiate Toxic Anterior Segment Syndrome From Endophthalmitis?

Endophthalmitis is a common inflammatory condition of the eye seen post-operation, just like toxic anterior segment syndrome.

• The primary difference between these two is that toxic anterior segment syndrome-associated symptoms occur in less than two days, whereas endophthalmitis occurs between three-seven days.

• Pain in the anterior segment syndrome is mild to moderate, whereas severe in the other case.

• Intraocular pressure increases in toxic anterior segment syndrome and is not usually elevated in endophthalmitis.

• Prognosis is better with toxic anterior segment syndrome management than endophthalmitis.

What Are the Clinical Features of Toxic Anterior Segment Syndrome?

• Severe inflammatory infection of the anterior chamber after a day or two of eye surgery.

• Mild to severe pain.

• Sensitive to light.

• Reduced vision.

• Increased intraocular pressure.

• Swelling of the corneal layer limbus to limbus.

• Accumulation of neutrophils and fibrin in the anterior chamber (hypopyon).

• Dilated pupils.

What Is the Pathophysiology of Toxic Anterior Segment Syndrome?

The condition is caused by the accumulation of toxic agents in the eye's anterior chamber. In this process, the endothelial cells of the corneal layers are broken down, resulting in loss of function (barrier). The remaining active endothelial cells will spread over the damaged layer to prevent further damage. Since only a few active cells are present, the damage will progress and result in corneal edema. The classic feature of the condition is inflammation of the eye's anterior chamber.

How to Diagnose Toxic Anterior Segment Syndrome?

Patients who are to be investigated for toxic anterior segment syndrome will also have to undergo tests for infectious endophthalmitis.

Tests to Detect Endophthalmitis:

A series of laboratory tests like gram's staining and culturing will be performed that include procedures like,

• Aspiration of the anterior chamber.

• Vitreous biopsy.

Also, B scan ultrasonography will be performed to rule out Vitritis (creamy white cotton-like lesion of the retina and choroid extending into the vitreous cavity).

Tests to Detect Toxic Anterior Segment Syndrome:

A complete eye examination is advised.

The tests include,

Physical Examination: The eye doctor will examine the eyes for,

1. Corneal edema from limbus to limbus is considered the classic sign of anterior segment syndrome.

2. Levels of intraocular pressure.

Visual Acuity: Using the Snellen eye chart (the chart comprises alphabets and numbers from bigger to smaller), the patient will be asked to read out the alphabets and numbers from 6 feet away. This is used to evaluate the vision power.

Slit Lamp Test: This test is helpful in profoundly studying the eye's layers and diagnosing the conditions. Here a microscope attached to a slit lamp is used to illuminate the eyes of the patient sitting across and study the layers of the eye.

Dilated Fundus Examination: The patient's eye will be introduced with a few drops of mydriatic eye drops to dilate the pupil and study the fundus (area opposite the lens) of the eye.

Goldmann Applanation Tonometry: This test is used to measure the pressure of the eyes. It is considered the gold standard.

How to Manage Toxic Anterior Segment Syndrome?

Medications:

Generally, surgery will not be preferred until there is no hope with medications. Suppose diagnosing the condition is unsuccessful, and there are few doubts regarding the causative factor. In that case, it is good to begin treatment for toxic anterior segment syndrome and endophthalmitis. To begin with, topical steroids will be prescribed to be used every 30 - 60 minutes for two-three days. Follow-up of the patient is essential. If it is toxic anterior segment syndrome, topical steroids will ease the condition, whereas, in endophthalmitis, it will only worsen (steroids are not enough). Elevated intraocular pressure is to be treated to prevent optic nerve damage.

Surgical Intervention:

• If there is a severe fibrin reaction, an intracameral recombinant tissue plasminogen activator is useful.

• If the intraocular lens is found to be the cause, replacing it is necessary.

• Corneal transplantation is preferred if the corneal edema is seen after six weeks.

What Are the Complications of Toxic Anterior Segment Syndrome?

• Glaucoma (trabecular meshwork damage).

• Iris sphincter muscle damage.

• Cystoid macular edema (retinal swelling to form multiple fluid cyst-like areas in the macula).

• Pain.

• Loss of vision.

How to Prevent Toxic Anterior Segment Syndrome?

• Follow proper sterilization techniques.

• Using properly sterilized surgical instruments.

• Using sterile and appropriate irrigation solutions.

• Consuming the medications as prescribed by the doctor before and after surgery.

Conclusion

This condition is totally out of hand, and The medical world is trying its best to eradicate the same. This condition will generally cause panic in the patients but reaching out to the doctor immediately increases the chances of resolving it earlier.