Shingles, or herpes zoster, is a viral infection causing a painful rash. It results from the reactivation of the varicella-zoster virus (VZV), the same virus that causes chickenpox. After chickenpox, VZV remains dormant in nerve tissues and can reactivate years later. While the rash often appears on the torso, shingles can affect various body parts, including the eyes.
How Shingles Reaches the Eye
Ocular shingles occurs when the dormant varicella-zoster virus reactivates in the trigeminal ganglion. This cluster of nerve cells is responsible for sensation in the face. The virus then travels along the ophthalmic branch (V1) of the trigeminal nerve. This nerve branch supplies sensation to the forehead, upper eyelid, and the eye itself. Reactivation in this area leads to herpes zoster ophthalmicus (HZO).
Recognizing the Signs
Initial symptoms often include tingling, itching, or burning in the scalp, forehead, or around the eye. A characteristic red, painful skin rash with fluid-filled blisters appears afterward. This rash is usually unilateral, affecting only one side of the face, including the forehead, eyelid, or areas around the eye.
Hutchinson’s sign, the presence of blisters on the tip of the nose, is a specific indicator of potential eye involvement. This suggests the nasociliary nerve, which also supplies the eye, is affected, increasing the likelihood of ocular complications. Other common symptoms include severe pain or throbbing in the eye, redness and swelling of the eyelid, and photophobia (sensitivity to light). Blurred vision can also occur. These ocular symptoms often accompany or follow the skin rash.
Damage to Eye Tissues
Shingles can cause inflammation and damage to various eye structures. The cornea, the clear front surface, is frequently affected, leading to keratitis. This inflammation can result in corneal ulcers, scarring, and permanent vision loss.
Internal eye structures like the iris and ciliary body can also become inflamed, a condition known as uveitis or iritis. Uveitis can cause pain, redness, and light sensitivity, and may lead to increased eye pressure, potentially resulting in glaucoma or cataracts.
In rarer instances, the retina, the light-sensitive tissue at the back of the eye, can become inflamed (retinitis), which can severely impair vision and may progress to acute retinal necrosis. Inflammation of the optic nerve (optic neuritis) can also occur, potentially leading to vision loss. Eyelids may experience scarring or deformation from the rash.
Diagnosis and Management
Diagnosis of ocular shingles involves examination by a healthcare professional, often an ophthalmologist. This includes evaluating the rash and symptoms. Laboratory tests, such as polymerase chain reaction (PCR) to detect VZV DNA from a fluid sample, may confirm the diagnosis.
Treatment primarily involves antiviral medications like acyclovir, valacyclovir, or famciclovir, which reduce viral replication. These medications are most effective when started within 72 hours of rash onset to minimize complications.
Depending on affected eye structures, topical eye drops, including steroids to reduce inflammation or lubricating drops for comfort, may also be prescribed. Pain management is important. Early medical intervention helps prevent severe and potentially permanent complications.
Preventing Ocular Shingles
Vaccination is the primary method for preventing shingles, including its ocular form. The recombinant zoster vaccine, Shingrix, reduces the risk of developing shingles and its complications. This vaccine is recommended for healthy adults 50 years and older.
Shingrix is administered as a two-dose series, two to six months apart. It is over 90% effective in preventing shingles in adults 50 and older, and similarly effective for those 70 and older. It also significantly reduces the risk of ocular shingles, with effectiveness of approximately 73% to 89% against herpes zoster ophthalmicus.