Toxic Anterior Segment Syndrome
Encyclopedia
Toxic Anterior Segment Syndrome (TASS) is an acute, sterile anterior segment
inflammation
following generally uneventful cataract
and anterior segment surgery.
One of the main factors in differentiating TASS from an infectious endophthalmitis
is the rapid onset. Most patients with TASS will develop symptoms within 12 to 24 hours of the surgery. Common findings on anterior segment slit lamp
examination include increased cell and flare with associated fibrin
and possible hypopyon
formation. Patients may show signs of diffuse corneal edema, and they may also show signs of iris
atrophy
with pupillary abnormalities and eventual increased intraocular pressure.
It is important to differentiate sterile postoperative inflammation from infectious endophthalmitis as the evaluation and treatment of these patients are markedly different. Patients with TASS will often respond quite rapidly to treatment with intense topical corticosteroid
s. It is important that the patients be evaluated often to ensure that the inflammation is clearing and that the patient’s intraocular pressure
is under control. The clearing of the inflammation and eventual patient outcome is related to the severity of the toxic insult at the time of surgery. Fortunately, most patients reported to date are in the category of a moderate toxic inflammation.
TASS may be related to problems with any irrigating solution or other solution placed in the patient’s eye during surgery including Balanced Salt Solution (BSS) or anything added to the BSS. Material placed in the eye during surgery such as anesthetics, Ophthalmic Viscoelastic Devices (OVD), antibiotics, or other medications has been found to be related to TASS. Problems related to the cleaning and sterilization of instruments for cataract surgery have been found to be a common source of TASS.
Anterior segment
The anterior segment is the front third of the eye that includes the structures in front of the vitreous humour: the cornea, iris, ciliary body, and lens.Within the anterior segment are two fluid-filled spaces:...
inflammation
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
following generally uneventful cataract
Cataract
A cataract is a clouding that develops in the crystalline lens of the eye or in its envelope, varying in degree from slight to complete opacity and obstructing the passage of light...
and anterior segment surgery.
One of the main factors in differentiating TASS from an infectious endophthalmitis
Endophthalmitis
Endophthalmitis is an inflammation of the internal coats of the eye. It is a dreaded complication of all intraocular surgeries, particularly cataract surgery, with possible loss of vision and the eye itself. Infectious etiology is the most common and various bacteria and fungi have been isolated as...
is the rapid onset. Most patients with TASS will develop symptoms within 12 to 24 hours of the surgery. Common findings on anterior segment slit lamp
Slit lamp
The slit lamp is an instrument consisting of a high-intensity light source that can be focused to shine a thin sheet of light into the eye. It is used in conjunction with a biomicroscope...
examination include increased cell and flare with associated fibrin
Fibrin
Fibrin is a fibrous, non-globular protein involved in the clotting of blood. It is a fibrillar protein that is polymerised to form a "mesh" that forms a hemostatic plug or clot over a wound site....
and possible hypopyon
Hypopyon
Hypopyon is pus in the eye.It is a leukocytic exudate, seen in the anterior chamber, usually accompanied by redness of the conjunctiva and the underlying episclera. It is a sign of inflammation of the anterior uvea and iris, i.e. iritis, which is a form of anterior uveitis...
formation. Patients may show signs of diffuse corneal edema, and they may also show signs of iris
Iris (anatomy)
The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...
atrophy
Atrophy
Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations , poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, disuse or lack of exercise or disease intrinsic to the tissue itself...
with pupillary abnormalities and eventual increased intraocular pressure.
It is important to differentiate sterile postoperative inflammation from infectious endophthalmitis as the evaluation and treatment of these patients are markedly different. Patients with TASS will often respond quite rapidly to treatment with intense topical corticosteroid
Corticosteroid
Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...
s. It is important that the patients be evaluated often to ensure that the inflammation is clearing and that the patient’s intraocular pressure
Intraocular pressure
Intraocular pressure is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk from glaucoma...
is under control. The clearing of the inflammation and eventual patient outcome is related to the severity of the toxic insult at the time of surgery. Fortunately, most patients reported to date are in the category of a moderate toxic inflammation.
TASS may be related to problems with any irrigating solution or other solution placed in the patient’s eye during surgery including Balanced Salt Solution (BSS) or anything added to the BSS. Material placed in the eye during surgery such as anesthetics, Ophthalmic Viscoelastic Devices (OVD), antibiotics, or other medications has been found to be related to TASS. Problems related to the cleaning and sterilization of instruments for cataract surgery have been found to be a common source of TASS.