What is Neuroretinitis?
Neuroretinitis (NR) is a condition that involves inflammation in the front part of the optic nerve and the part of the retina around it. This condition usually causes vision loss and is accompanied by swelling of the optic disc (the area where the optic nerve enters the eye) and a star-shaped pattern of fluid buildup in the macula, the center of the retina. This doesn’t point to a specific cause or source of the problem.
Neuroretinitis was first identified in 1916 by Theodor Leber and was originally thought to start in the macula (a term reflected in the name ‘stellate maculopathy’). However, later studies showed that the leakage of fluid actually starts at the optic disc and then affects the macula. This led to the term “neuroretinitis”.
Various infections and inflammation-related causes have now been linked to neuroretinitis. Most cases tend to clear up on their own, but it’s important to understand that sometimes the recovery may be minor or the disease may come back, so early treatment may be necessary.
Neuroretinitis can be categorized in different ways: idiopathic (meaning its cause is unknown), idiopathic-recurrent, and cat-scratch-disease neuroretinitis (a type of neuroretinitis caused by an infection from cat scratches). Additionally, it can be classified based on whether it is caused by an infection or not, with idiopathic and idiopathic-recurrent neuroretinitis usually being non-infectious. Typically, neuroretinitis affects one eye at a time, but if it affects both eyes, the doctor should look for other possible explanations.
What Causes Neuroretinitis?
Cat-scratch disease, which happens due to infection with a type of bacteria called Bartonella henselae, is often linked to a condition affecting the eyes known as neuroretinitis. This disease is responsible for two-thirds of neuroretinitis cases. But it can also lead to other eye problems, such as Parinaud’s syndrome (an eye and gland condition), retinitis (inflammation of the retina), uveitis (inflammation inside the eye), retinal vasculitis (inflammation of the blood vessels in the retina), and retinal detachment (when the retina pulls away from its normal position). However, neuroretinitis remains the primary symptom in 88% of cat-scratch disease patients, according to a study of 107 eyes of 86 patients.
Neuroretinitis can also be caused by other infections including:
– Lyme disease
– Syphilis
– Tuberculosis
– Salmonella
– Chickenpox and shingles
– Measles
– Mumps
– German measles (Rubella)
– West Nile virus
– Zika virus
– Chikungunya virus
– Flu (Influenza)
– Hepatitis
– Epstein-Barr virus
– Histoplasmosis
– Coccidioidomycosis
– Actinomycosis
– Toxoplasmosis
– Toxocariasis
– Hepatitis B
– Leptospirosis
– Typhus
Further, inflammation-related diseases can also result in neuroretinitis, including:
– Sarcoidosis (inflammatory disease affecting multiple organs)
– Lupus (autoimmune disease)
– Behçet’s disease
– Polyarteritis nodosa
– Takayasu’s arteritis
– Vogt-Koyanagi-Harada disease
– Inflammatory bowel disease, although it’s rarely associated with neuroretinitis.
In half of the cases, we simply don’t know what causes neuroretinitis – this condition is termed idiopathic neuroretinitis.
Risk Factors and Frequency for Neuroretinitis
There’s limited information on how common Neuroretinitis (NR) is, as it’s often not diagnosed right away. This is because signs like disc swelling and star-like spots on the retina (macular star formation) don’t happen at the same time – there’s usually a gap of one to two weeks.
- Neuroretinitis tends to affect young adults between the ages of 8 and 40, most commonly at the age of 24.
- Women are more likely to get CSD-NR, a type of Neuroretinitis, than men, with a ratio of 1.8 women for every man. However, other types of Neuroretinitis do not seem to affect one gender more than the other.
- There is a suspicion that Neuroretinitis may be more prevalent in the Mid-Western United States, but this hasn’t been confirmed yet.
Signs and Symptoms of Neuroretinitis
Neuroretinitis often causes vision loss, which is usually in one eye but can affect both. The condition often begins with swelling of the optic disc in the eye. This may also include flame-like hemorrhages at the disc. If there’s significant swelling or signs of retinal blood vessel blockage, the doctor may need to look for other conditions. Fluid may accumulate around the optic disc, and can sometimes be missed unless special imaging like optical coherence tomography (OCT) is used. In some cases, this fluid can create a small detachment of the retina. After the swelling and fluid go away, you may notice a star-like pattern of fatty residues in the eye.
About three weeks after onset, the longer the fluid stays, the more damage it may cause to the light-sensitive cells of the eye, indicating that treatment should start. Changes in vision may range from 20/20 vision to just light perception, and they can sometimes be worse in certain types of neuroretinitis. The loss of the visual field can change greatly, but usually, it is in the center or in an area around the center. In some instances, a type of visual field defect known as a central scotoma may occur with an arcuate defect. Eye pain or pain behind the eye is rare, if severe pain is experienced, other causes should be looked into.
A condition known as ‘relative afferent pupillary defect’ (RAPD) may be seen in many cases, particularly in about two-thirds of a certain type of neuroretinitis. However, the presence or absence of RAPD does not confirm or rule out neuroretinitis. The presence of cells in the vitreous humor, the clear gel that fills the space between the lens and retina, can show the inflammatory nature of the condition.
It’s important for the doctor to take a thorough medical history. They will need to ask about any recent flu-like symptoms, as well as risk factors for other conditions like Lyme disease (tick bites and skin rashes), sexually transmitted infections, and tuberculosis. A detailed review of your overall health and travel history is necessary in all cases of neuro-ophthalmic conditions.
Testing for Neuroretinitis
Your doctor may order several available and useful lab tests if they suspect certain diseases. These can include tests for illnesses such as syphilis, tuberculosis, Bartonella, and Borrelia.
Optical coherence tomography (OCT) is a type of eye imaging technique that is incredibly helpful in examining the optic disc and the macula of your eye. The optic disc is the spot in the back of your eye where the optic nerve enters, and the macula is the part of your eye that provides sharp and central vision. This method can identify fluid that is trapped beneath or within the retina that may not be found during the early stages of a routine eye exam.
OCT can show signs of a condition called neuroretinitis, such as a change in the shape of a part of the eye called the fovea, fluid in specific layers of the retina, or fluid beneath the retina, before a characteristic swelling pattern (macular star) becomes apparent.
Right at the beginning stages, OCT might reveal clusters of cells in the jelly-like filling of the eye in front of the optic disc, even before they can be seen on a special type of eye exam using a tool known as a slit-lamp.
This discovery is important, especially in unclear cases, because it helps differentiate causes of optic disc swelling which are due to inflammation or infection from non-inflammatory ones like papilledema (swelling caused by increased pressure around the brain) and ischemic optic neuropathy (damage to the optic nerve due to insufficient blood flow).
Furthermore, with OCT, the extent of fluid trapped within and beneath the retina and the degree of optic disc swelling can be measured and tracked with repeated scans. This provides vital information to your doctor to predict whether your vision is likely to improve within the first few weeks. It’s crucial to note if the fluid is extensive or lingering since it may indicate a lower likelihood of vision recovery.
Fundus fluorescein angiography is another safe and helpful tool used to determine the exact location of leakage, identify less visible eye pathologies such as inflammation and blockage of the blood vessels in the retina, and record diabetic or hypertensive retinopathy (eye damage due to diabetes or high blood pressure). With neuroretinitis, leakage should start in the optic disc and may be segmented. It can also pinpoint leakage from a single vessel at the front of the optic disc. It can also highlight subtle swelling within the opposite optic disc where a condition affecting both eyes might be otherwise missed.
Magnetic resonance imaging (MRI) is often used when the diagnosis is unsure. It’s usually normal but can sometimes show enhancement of the optic disc, which may even extend a bit within the portion of the optic nerve inside your eye socket. Rarely, the sheath that surrounds the optic nerve may show enhancement. This scan is critical to exclude other potentially treatable conditions that cause optic nerve inflammation or compression.
Treatment Options for Neuroretinitis
The best method to treat the illness
mentioned often varies because the causes can be different, it’s not very common, and mostly, it gets better on its own. If we know what’s causing the disease, we should treat that. It’s also widely agreed that most unidentified causes of the disease and most diseases that don’t respond to cat scratch treatment will get better without intervention. However, we don’t have enough clinical trials to show us what we should do in these or other cases, and medical experts are still discussing this.
For a more severe form of cat-scratch disease that involves fever and swollen lymph nodes, research has shown that a course of a drug called azithromycin reduces the swollen node more quickly than without any treatment.
Previous research has examined treating another form of the disease that doesn’t respond to routine cat scratch treatment with antibiotics, steroids, or a combination of antibiotics and steroids. Antibiotics that are often used include azithromycin, ciprofloxacin, and doxycycline, often combined with rifampin. These treatments can speed up recovery, but it’s important to note that most cases do get better on their own, especially in mentally and physically healthy patients.
More recent expert opinion and analysis of evidence suggest that for patients experiencing severe vision loss or significant bodily symptoms, treatment with doxycycline or azithromycin, along with rifampin, for 4-6 weeks might provide some benefit. Routine use of steroids, however, is not recommended.
Lastly, for patients who continue to experience neuroretinitis, a form of inflammation of the optic nerves and retina, long-term usage of azithromycin might be necessary.
What else can Neuroretinitis be?
There are some other health issues which can cause disc swelling with fluid building up underneath the retina, or a pattern in the retina that looks like a star. These conditions include:
- Hypertensive retinopathy (commonly affects both eyes)
- Papilledema (usually affects both eyes or is uneven)
- Anterior ischemic optic neuropathy
- Vasculitis
- Diabetic papillopathy.
So, it is really important for doctors to check each patient’s blood pressure and heart rate. They also need to ask patients about any symptoms that could suggest high pressure inside the skull or other illnesses affecting the whole body.
What to expect with Neuroretinitis
In cases of idiopathic NR and CSD-NR, which are certain types of vision impairments, about 97% of people regain a good level of vision clarity, technically known as 20/40 or better. This means that what a normal eye sees at 40 feet, a 20/40 eye sees at 20 feet.
However, for people with recurrent idiopathic NR, which is a condition where the same vision-related issue happens repeatedly, only 36% recover to the 20/40 vision level. This is due to the cumulative damage caused by recurring incidents.
Depending on how severe the episode is, there could be changes in the optic disk – the area at the back of the eye where the optic nerve connects to the retina. This can result in sectoral (a part) or diffuse (spread out) pallor – a pale or whitening appearance. This is an indication that permanent loss of neurons, or nerve cells, has occurred in the eye.
Possible Complications When Diagnosed with Neuroretinitis
If neuroretinitis, an infection of the eye, keeps coming back or gets worse, it can permanently harm your vision. This could lead to less sharp vision or blind spots. Therefore, it’s best to get treated if you have serious vision loss, blind spots, or a weakened immune system. Other complications can occur based on the specifics of each person’s health condition.
Common Complications:
- Permanent damage to vision
- Less sharp vision
- Blind spots in vision
- Complications due to a weaker immune system
- Potential other complications depending on individual health conditions
Preventing Neuroretinitis
Currently, there are no known ways to prevent this eye condition. However, if you’re experiencing significant vision loss that affects your daily life, there are resources available to help. This might include practical tools designed for those with low vision, such as magnifiers or lighting equipment, that can help improve your visual function.
