Iritis is an eye condition that is caused by the inflammation in the iris of the eye. Iris is a circular, colored, front portion of the eye, surrounding the dark pupil. Iris is filled with muscular fibers which regulate the amount of light entering the pupil. It allows the pupil to contract in bright light and enlarges it in dim light. When this iris becomes inflamed, it is termed as iritis or anterior uveitis, whereas the inflammation at the back of the eye is called posterior uveitis. Iritis causes severe pain, light sensitivity and may even lead to sight loss on rare occasions.
What causes iritis ?
Iritis can occur in one or both the eyes. The causes to iritis can be traumatic or non traumatic. Iritis caused by the trauma or injury to the eye is called traumatic iritis. Infections such as shingles or syphilis can lead to iritis or uveitis. Iritis may also occur due to certain autoimmune diseases present in the body like Ankylosing spondylitis, reactive arthritis, psoriatic arthritis, irritable bowel disease and tuberculosis. This condition is known as Non traumatic iritis. In most cases, it becomes difficult to find the cause for iritis.
Symptoms of iritis
The symptoms of the iritis surface suddenly and initially it affects one eye. Some of the symptoms of iritis are mentioned below:
Iritis, if left untreated, may give rise to complications such as cataract, glaucoma, retinal detachment and vision loss. Hence it is advisable to seek medical help on finding any of the symptoms. Firstly, the ophthalmologist makes a complete note of your medical history and conducts a thorough eye examination. A slit light is focused on the affected eye to have a better view of the structure and any signs of inflammation. Since iritis is associated with some autoimmune diseases, your doctor may advise few tests to find out the exact cause.
Your eye doctor will prescribe dilating eye drops - Cycloplegics to dilate your pupil and relieve you of the pain. These drops also prevent the scarring of the pupil. Patients complaining of sensitivity to light will be given dark glasses. Steroid eye drops and antibiotics also may be given to reduce the inflammation. These drops settle the cell membrane and regulate the movement of the white blood cells in your eye. If the problem persists or worsens you may be given oral steroids, injections and other anti inflammatory drugs.
Normally, traumatic iritis disappears with proper and timely treatment, but, chances of recurring cannot be ruled out in case of non-traumatic iritis. In such cases, the relapse of iritis depends upon how well the underlying causes are diagnosed and treated.
Herpes Zoster Ophthalmicus
Herpes zoster ophthalmicus HZO, also known as Ocular Shingles, is a painful dermatomal rash around the eye region and forehead caused by the reactivation of the Varicella Zoster Virus (VZV). It affects the trigeminal nerve of the ophthalmic division and eventually spreads to the other structures of the eye. The first division of the trigeminal nerve is the most common site for the development of acute herpes zoster.
Varicella-zoster virus manifests at two different stages in humans. At primary level the virus causes chicken pox after which it remains dormant for several years and reappears as herpes zoster later in the patient’s life. Aging, poor nutrition and low immunity are some of the risk factors that leads to the outbreak of Herpes zoster ophthalmic us (HZO).
HZO begins with flu-like symptoms including fever, Myalgia, and malaise for nearly a week. Typically, patients then develop tingling sensation and painful rash on the forehead and ocular symptoms such as eyelid edema; conjunctival, episcleral and circumcorneal conjunctival hyperemia; corneal edema and light sensitivity. All these symptoms are unilateral - occurring on one side of the face.
Herpes zoster ophthalmicus (HZO) is diagnosed clinically by mere observation of the symptoms. During a clinical visit, the ophthalmologist conducts a detailed examination of visual acuity, visual fields, extra ocular movements, pupillary response, corneal function, Intraocular Pressure and anterior chamber. Doctor also makes a note of past history of chicken pox infection along with clinical examination. Viral culture, direct immunofluorescence assay, or Polymerase chain reaction (PCR) may also be used to confirm the diagnosis. Any signs of Hutchinson disease strongly indicates ocular complications such as inflammation and corneal denervation and forms the basis for diagnosis of herpes zoster ophthalmicus.
Herpes zoster ophthalmicus is a medical emergency and should be treated promptly to avoid vision loss. The disease leads to many ocular conditions such as dermatitis, corneal pseudo-dendrites, uveitis, retinitis, and in rare cases it also causes cranial nerve palsies. Oral anti viral medicines like Acyclovir and Famcyclovir play a major role in treating herpes zoster ophthalmicus. Atropine eye drops are also prescribed to alleviate the painful symptoms. In case keratitis develops, Corticosteroid drops along with Cycloplegics (eye drops to induce ciliary muscle paralysis) may also be considered.
The Human Leukocyte Antigen HLA are proteins or markers that are present on the White blood cells and tissues of the body. HLA test, also known as HLA typing or tissue typing, identifies antigens on the WBCs that determine tissue compatibility for organ transplantation. These HLA markers are inherited from parents. This test is performed for kidney, bone marrow, liver, pancreas, and heart transplants. The transplant will be successful if HLA of donor closely matches with HLA of the patient. If the HLA of the donor and recipient do not match, the immune system of the recipient will assume the donor's HLA antigens as foreign. This causes rejection of the transplanted tissue or organ. This condition is called GVHD or Graft Vs Host disease. Recipients who receive mismatched transplant are at the highest risk of developing this condition. However, GVHD can occur even with proper HLA matching. HLA test also screens recipients for the presence of antibodies that might attack the transplanted tissue or organ as part of an immune response.
Though HLA typing is normally used to screen patients and donors for matching HLA antigens, it can also be undertaken for diagnostic purposes. The presence of HLA antigen B27 is explored to diagnose certain auto immune diseases like ankylosing spondylitis, reactive arthritis and anterior uveitis. HLA-DR15, HLA-DQ6 is associated with Narcolepsy.
Each HLA gene can have huge number of variations called alleles. There are 3 general groups of HLA that play an important role in matching prior to transplantation. They are the A, B and DR antigens. These are inherited from parents, one set of A, B and DR from mother and another set of A, B and DR from father. Thus there are two antigens for each letter and they are identified by different numbers.
HLA Test Process
HLA Test matches alleles of donors and recipients either by performing serological HLA testing or molecular (DNA) typing. Children from the same set of parents are likely to have the best HLA match possible. There is 1 in 4 chances that siblings will inherit the same genes from their parents. This is considered as ideal match.
Once the match has been identified, the next step would be to test for antibodies in the recipient. It is a vital step in HLA testing as antibodies have the potential to attack donor tissues that have the corresponding HLA type.
After testing for antibodies in the recipient, cross matching test is performed to identify donor specific antibodies. Cross matching is performed right before transplant. A cross match determines if the recipient's body contains antibodies formed against the potential donor's antigens. To perform the cross matching, a small amount of the recipient's serum is combined with the donor's white blood cells (T and B lymphocytes). If the recipient has antibodies that are specific to donors HLAs, the donors cells get damaged. This type of reaction is called positive cross match and indicates the incompatibility between recipient and the donor. A blood sample is needed to perform HLA typing. Testing is done using white blood cells and DNA. It takes about two weeks to receive the results.
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Bibliography / Reference
Collection of Pages - Last revised Date: April 1, 2020