Iritis
Iritis is a term describing inflammation of the eye structures surrounding iris. Iritis is used interchangeably with another condition called anterior uveitis. Uveitis is more involved inflammation of the eye that can affect the optic nerve, sclera, and retina. In a way, this terminology is important to the ophthalmologists to describe the segments of the eye that are inflamed.
In this article:
- What Is Iritis?
- Symptoms
- When to see a doctor
- Causes
- Risk Factors
- Iritis Exams and Diagnosis
- Can iritis be prevented?
- References
What Is Iritis?
Uveitis can affect people of all ages and can vary significantly by geographic location and age of the patient. In a study done from 2006 to 2007, the incidence of uveitis was 24.9 cases per 100,000 persons. Iritis is the most prevalent form, accounting for approximately 50% of uveitis cases, while posterior uveitis is the least common.
Uveitis may be triggered by genetic, immune, traumatic, or infectious mechanisms. In such situations the inflammation of the eye is more of a symptom, and other organs are also involved. When no specific reasons for the iritis are found, it is called idiopathic. Idiopathic cases account for 48 to 70% of uveitis cases.
Uveitis can be further subdivided into anterior, intermediate, posterior, and panuveitis based on the primary anatomical location of the inflammation in the eye. Symptoms and consequences can range from pain and conjunctival injection to complete vision loss.
Anterior uveitis is epitomized by the anterior segment being the predominate site of inflammation. Intermediate uveitis is defined by inflammation of the vitreous cavity and pars plana, while posterior uveitis involves the retina and choroid. Inflammation in panuveitis includes all layers.
Symptoms of uveitis depend on the type (anterior, posterior, or intermediate) and duration (acute or chronic).
Ongoing inflammation seen in untreated uveitis and complications related to this uncontrolled inflammation are estimated to be responsible for approximately 10% of the blindness in the United States.
Symptoms
The first symptoms of iritis are not very specific and can happen in other eye diseases:
- Eye redness
- Eye pain
In anterior uveitis, the affected pupil maybe constricted or irregular in shape when compared to the unaffected eye due to adhesions formation.
Symptoms will vary depending on the structure that is inflamed. Acute anterior uveitis can be unilateral or bilateral (an autoimmune disease) with symptoms including blurred vision and photophobia.
A complete past medical, family, and ophthalmic history (specifically surgical) is necessary for a proper diagnosis.
When to see a doctor
There are plenty o different reasons for the red painful eye:
- Anterior uveitis
- Keratitis
- Corneal abrasion
- Acute angle closure glaucoma
- Conjunctivitis
- Scleritis
All these conditions can be potentially dangerous for the vision. It is important to see a doctor if the eye pain and redness is increasing and continuous.
Causes
Systemic inflammatory disorders commonly associated with anterior uveitis include:
- HLA-B27-associated eye inflammation
- Juvenile idiopathic arthritis
- Inflammatory bowel disease
- Sarcoidosis
- Behcet’s disease
- Tubulo-interstitial nephritis.
Multiple sclerosis, sarcoidosis, and tubulo-interstitial nephritis are causes of intermediate uveitis with systemic manifestations, while Vogt-Koyanagi-Harada syndrome, leukemia, lupus, Behcet’s disease, and multiple sclerosis can cause a posterior uveitis with systemic manifestations.
Behcet’s disease is a systemic vasculitis that can also present with pan-uveitis. Infectious processes are thought to account for approximately 20% of all uveitis cases but underlying causes can vary geographically.
- viruses (HSV, VZV, CMV),
- bacteria (endophthalmitis, syphilis, tuberculosis, etc),
- parasites/worms (toxoplasmosis, Lyme Disease, toxocara, Bartonella sp. or other atypical infections).
Viral anterior uveitis (VAU) needs to be suspected in anterior uveitis (AU) associated with elevated intraocular pressure, corneal involvement, and iris atrophic changes. Common etiologies of VAU include herpes simplex, varicella-zoster, cytomegalovirus, and rubella virus.
Clinical presentations can vary from granulomatous AU with corneal involvement, Posner-Schlossman syndrome, Fuchs uveitis syndrome, and endothelitis. Due to overlapping clinical manifestations between the different viruses, diagnostic tests like polymerase chain reaction and Goldmann-Witmer coefficient analysis on the aqueous humor may help in identifying etiology to plan and monitor treatment.
Cat-scratch disease (Bartonella) occurs in immunocompetent individuals of all ages worldwide. It is the leading cause of regional lymphadenopathy in children and young adults. Patients will present with tender, swollen lymph nodes at or near the site of the bite or scratch. It is the most common cause of neuroretinitis. Other forms of ocular inflammation include intermediate uveitis, anterior uveitis, conjunctivitis, retinal vasculitis, and orbital abscess.
Lyme disease (Borrelia) is a multisystem disorder caused by the spirochete Borrelia burgdorferi infection and its sequelae and is transmitted via tick bites. In the USA, cases are highly concentrated in the northeast, mid-Atlantic, and upper Midwest regions. There are three stages of Lyme disease: the early stage, disseminated stage, and persistent stage. In the early stage of the disease, 60%–80% of patients present with the classic “Bull’s eye” red macular rash at the site of the tick bite 2–28 days after the bite. Fever, malaise, fatigue, arthralgias, and myalgias often accompany the rash. The disseminated stage occurs several weeks after the initial exposure, and the patients may develop skin, nervous system, joint, heart, and eye problems. Uveitis may be present at the disseminated and persistent stages of the disease; anterior uveitis, intermediate uveitis, posterior uveitis, neuroretinitis, retinal vasculitis, choroiditis, and panuveitis have all been reported.
TB is an airborne infectious disease caused by Mycobacterium tuberculosis. Granulomas may be noted on the iris, angle, or choroid. Uveitis may present in active TB and in patients with or with-out systemic TB symptoms. Uveitis is the most common ocular manifestation of TB.
The most common uveitis seen in TB is disseminated chorioretinitis, but it can also present as acute anterior uveitis, chronic granulomatous anterior uveitis, intermediate uveitis, vitritis, or endophthalmitis. Broad-based posterior synechiae and retinal vasculitis are common with the uveitis presentation.
Toxoplasmosis is caused by the parasite Toxoplasma gondii and is the leading cause of posterior uveitis worldwide. It is spread through eating undercooked meat or from exposure to cat feces. Classically, toxoplasmosis presents as a yellow-white or gray exudative chorioretinal lesion with ill-defined borders in the retina with a marked vitritis. This is known as “headlight-in-the-fog”. Anterior uveitis may also be present, usually with a granulomatous response, including mutton-fat KPs, posterior synechiae, iris nodules, and fibrin deposition.
Toxocariasis is an infectious disease caused by the larvae of the parasites Toxocara canis or Toxocara cati that are present in the small intestine of dogs and cats, respectively. The larvae reach the eye via the bloodstream and deposit, most commonly, in the retina. Chronic endophthalmitis with associated retinal detachment, low-grade anterior uveitis, posterior synechiae, and hypopyon may also be evident. Papillitis, macular edema, and vitreous exudates are also associated findings. If present in a child, the chief complaint may not be reduced visual acuity, but leukocoria.
Risk Factors
Although rare (<0.5% of cases at tertiary referral centers), a patient’s current medications may cause uveitis. The antiviral, cidofovir, for example, can cause anterior uveitis with or without hypotony in a significant number of patients. Checkpoint inhibitors (newer cancer drugs) are also becoming a well-known cause of mild to severe anterior, posterior, or panuveitis
Immunocompromised patients frequently develop eye disease, including parasytic and bacterial anterior uveitis. Patients with trauma of the eye or recent surgeries can develop anterior uveitis due to open access to bacteria.
Iritis Exams and Diagnosis
Physical exams should include visual acuity testing, slit lamp biomicroscopy, measurement of intraocular pressures, and a dilated eye exam. Signs seen on eye exam:
- anterior chamber cell and flare,
- ciliary flush
- posterior synechiae
- keratic precipitates
Pinhole visual acuity is also a good tool to use when the patient may have left their glasses at home or the patient is thought to have an untreated refractive error. This can be accomplished quite easily by poking a small hole through a styrofoam cup and having the patient look through that single hole to read the visual acuity chart.
Key diagnoses to rule out in every case of uveitis: syphilis, sarcoid, and tuberculosis. For anterior uveitis, consider testing for HLA-B27 typing, FTA/RPR, serum ACE/lysozyme, chest x-ray, and quantiferon gold. Neuroimaging for multiple sclerosis should be considered in the proper demographic population.
Findings and other associated systemic manifestations will call for other specialists involvement. As anywhere else in the body, syphilis is the “great masquerader” and should be considered in all cases of uveitis.
Acute angle closure glaucoma can present as a painful red eye with a change in vision. The patient may complain of a unilateral headache and maybe nauseous even to the point of vomiting. The affected pupil is often mid-dilated and poorly reactive to light. The intraocular pressure will be significantly increased in acute angle closure glaucoma and is typically seen in most causes of uveitis
Conjunctivitis can present as a painful red eye with photophobia. Bacterial conjunctivitis can present with purulent discharge which is not present in uveitis. Patients with viral or allergic conjunctivitis will usually have serous discharge and chemosis (swelling of the conjunctiva); however, they can also be without discharge. Other allergy symptoms and the lack of anterior chamber inflammation help make the diagnosis of conjunctivitis.
Other eye findings, if also found in the unaffected eye) such as posterior synechiae, cataract formation, rubeosis (blood vessels on the iris surface), and band keratopathy may suggest a longstanding inflammatory process or prior event. These findings can help aide in clarifying the differential diagnosis as a unilateral anterior uveitis versus a non-simulutaneous, bilateral anterior uveitis as they can have a different differential diagnosis.
On slit lamp exam, local or diffuse ciliary flush may be seen. One would also expect to see cell and flare in the anterior chamber. ”Cell” refers to a collection of white blood cells in the anterior chamber; the cells may be so dense that it has settled to form a white, dependent, hypopyon (layered white blood cells within the anterior chamber), signifying severe inflammation that should be evaluated by an ophthalmologist promptly.
Can iritis be prevented?
A healthy eye is a very protected organ that is rarely infected. To prevent iritis it is important to remember all safety measures for work-related eye injuries and eye protection in the toxic environment. Face shield will prevent toxic spills and vapors that may affect the cornea and cause surface damage.
Balanced diet is important to avoid nutritional deficiencies and keep your eyes healthy.
It is crucial to learn simple measures preventing viral diseases of the eye, such as hand washing and avoiding habits of touching and rubbing the eyes.