Uveitic glaucoma
Uveitic glaucoma is most commonly a progression stage of noninfectious anterior uveitis.
Noninfectious anterior uveitis is an inflammation of the anterior part of the eye and is instigated by autoimmune or other noninfectious causes. The onset of noninfectious uveitis occurs in patients in their thirties, with up to 10% of cases diagnosed in children under the age of 16. The condition may persist as a chronic disease.
Noninfectious uveitis is the most common form of uveitis in developed countries. Approximately 30% of uveitis patients develop glaucoma as a result of the inflammation that occurs in uveitis, as a complication of steroid treatment or a combination of both.
Uveitis, as well as steroid treatment for uveitis, can cause an increased resistance to the flow of aqueous humour from the eye. This leads to an excess of fluid buildup, which exerts elevated pressure on the inside parts of the eye, or elevated intraocular pressure. Elevated intraocular pressure can in turn lead to optic nerve damage and glaucoma.
Based on epidemiological studies of uveitis, approximately 34-94/100,000 people will develop uveitic glaucoma. Uveitic glaucoma patients are at significantly higher risk for visual field loss in the long term compared to patients who only have uveitis. Patients with uveitic glaucoma also experience a particularly high burden of care.
Signs and symptoms
Because uveitic glaucoma is a progressive stage of anterior non infectious uveitis, uveitic glaucoma involves signs and symptoms of both glaucoma and uveitis.Patients with acute non infectious anterior uveitis may experience the following symptoms: pain, blurry vision, headache, photophobia, or the observance of haloes around lights.
An ophthalmologist may be able to observe the main sign of active noninfectious anterior uveitis, which is the presence of immune cells floating within the anterior segment of the eye. The ophthalmologist also may observe peripheral anterior synechiae, or adhesions between the iris and trabecular meshwork, the tissue responsible for draining aqueous humour from the eye.
Patients with uveitis who also experience symptoms of glaucoma may have uveitic glaucoma.
In an eye with uveitic glaucoma, the following glaucoma signs may be observed: elevated intraocular pressure, scotomas in the field of vision, defects in the fiber layer of the retinal nerve, and/or excavation. Pupillary blocks, or the obstruction of "the flow of aqueous humor from the posterior chamber to the anterior chamber" due to a "functional block between the pupillary portion of the iris and the lens" may also be detected. Finally, the ophthalmologist may observe peripheral anterior synechiae, or adhesions between the iris and trabecular meshwork.
The dual presence of glaucoma and uveitis symptoms points to a diagnosis of uveitic glaucoma.
Causes
Uveitic glaucoma is a progressive stage of anterior noninfectious uveitis. Patients diagnosed with anterior noninfectious uveitis may also develop glaucoma; in this case the condition is termed uveitic glaucoma. Uveitic glaucoma can arise from the inflammation that occurs in uveitis; from steroid treatment for uveitis; or a combination of both.Uveitis inflammation
The inflammatory response associated with uveitis may lead to glaucoma. Active anterior uveitis flare-ups may develop quickly; in these cases, the inflammation can damage the tissues in the front part of the eye. Anterior uveitis may also be chronic; in these cases, repeated inflammation can cause progressive, accumulating damage to the eye tissues.In all cases — acute one-time episodes, recurrent chronic inflammation or acute-on-chronic inflammation — damage to the eye tissues can cause increased resistance to the outflow of aqueous humour from the eye, which then increases the pressure inside the eye. In some chronic uveitis cases, the pressure inside the eye waxes and wanes due to the uveitis flare-ups.
Elevated pressure inside the eye can lead to irreversible optic nerve damage and glaucoma.
Steroid treatment for uveitis
are the first-line treatment for an active flare-up of noninfectious anterior uveitis, and the only effective treatment available for active inflammation. However, steroid treatment for uveitis can lead to uveitic glaucoma. Corticosteroids increase the fluid pressure inside the eye by increasing resistance to the outflow of aqueous humour, which can cause optic nerve damage and glaucoma. Steroid treatment can therefore cause or worsen uveitic glaucoma.Elevated pressure inside the eye typically develops 2 to 6 weeks after starting corticosteroid therapy, but can occur at any time during corticosteroid therapy and may continue for weeks after steroid use has been stopped. According to the Glaucoma Research Foundation, the risk of developing chronic steroid-induced glaucoma increases with every week of steroid use.
Around 90% of patients with open angle glaucoma experience a steroid response of elevated intraocular pressure following steroid treatment. Therefore, once uveitis patients have developed uveitic glaucoma, they should ideally avoid steroids wherever possible.
Combination of uveitis inflammation and steroid treatment
In some cases, uveitis inflammation and steroid treatment both contribute to elevated pressure inside the eye, which leads to optic nerve damage and glaucoma.Pathogenesis
Uveitic glaucoma as a result of recurring uveitic inflammation
Uveitic glaucoma can develop as a complication of anterior uveitis resulting from the inflammatory response associated with the disease. The inflammatory response can be characterized by occlusion of the trabecular meshwork, or blocking of the tissue that is responsible for draining aqueous humour from the eye. Another characteristic that presents in some patients is peripheral anterior synechiae, or adhesions between the iris and trabecular meshwork. These two characteristics of the inflammatory uveitic response can lead to an increase in intraocular pressure, and consequently to irreversible optic nerve damage and glaucoma.Noninfectious uveitis is characterized by an inflammatory process that may be acute, recurrent, chronic or acute-on-chronic. Uveitic glaucoma is associated with an aggressive disease course caused by very high levels of intraocular pressure that wax and wane. When uveitis is acute, the onset of inflammation is rapid, with obstruction of intertrabecular spaces. When uveitis is chronic, recurrent bouts lead to tissue destruction from direct inflammation. Obstruction of the intertrabecular spaces characteristic of acute onset uveitis, as well as the repeated inflammation characteristic to chronic uveitis, can lead to elevated intraocular pressure. This can consequently cause optic nerve damage and glaucoma.
Uveitic glaucoma as a response to steroid treatment of uveitis
Uveitic glaucoma can also develop as a response to steroid treatment of uveitis. Corticosteroids cause a rise in the fluid pressure inside the eye. While the pathogenesis of corticosteroid-induced ocular hypertension is not fully understood, it likely involves swelling and remodeling of the trabecular meshwork, which leads to increased resistance to aqueous humour outflow and an increase in intraocular pressure. Another possible mechanism by which corticosteroids increase fluid pressure inside the eye is as follows:- Corticosteroids inhibit the breakdown of glycosaminoglycans in the trabecular meshwork.
- GAGs accumulate in the meshwork.
- Fluid drainage is decreased.
- Fluid pressure in the eye is increased.
Diagnosis
Uveitic glaucoma is a progression stage of noninfectious acute anterior uveitis. In order to diagnose uveitic glaucoma, a dual diagnosis of non-infectious anterior uveitis and glaucoma is required. A thorough examination of the eye by an ophthalmologist is performed in order to diagnose uveitic glaucoma.Noninfectious anterior uveitis
The main diagnostic sign of noninfectious acute anterior uveitis is the presence of anterior chamber cells, or immune cells, in the anterior, or front, chamber of the eye. The anterior chamber of healthy eyes does not contain any immune cells, hence the main indicator of noninfectious anterior uveitis is the presence of immune blood cells inside the anterior chamber of the eye. The more cells found floating in the anterior chamber, the more severe the uveitis.
The quantity of immune cells present in the anterior chamber can be determined via a slit lamp examination.
In 2005, an International Working Group on SUN took steps towards standardizing the methods for reporting clinical data in the field of uveitis. One of their products was a grading scheme for anterior chamber cells.
In 2021, a new slit lamp–based ACC assessment method, TGIS, was developed. TGIS uses a visual analog scale to enable pattern recognition-based evaluation of ACC density during a uveitic flare-up. This is achieved by graphically representing a high-power field slit beam through the anterior chamber, from the cornea to the lens surface.
Another important clinical measurement of ocular inflammation is flare. Flare is the leakage of various proteins into the ocular anterior chamber, as a manifestation of inflammation. It will usually have a "milky" appearance. Flare can also be observed via slit lamp examination.
Glaucoma
Glaucoma is a group of eye diseases that result in damage to the optic nerve and cause vision loss.
Glaucoma is challenging to diagnose and relies on several different methods of assessment to determine the level of optic nerve damage. These may include tonometry, a procedure to determine pressure inside the eye; a visual field test, which assesses peripheral vision; and imaging tests of the optic nerve.