What is MacTel?
The term MacTel most often describes idiopathic juxtafoveal macular telangiectasia Type 2. MacTel is an eye disease that affects a central area of the retina called the macula. For patients with MacTel, photoreceptors within the macula die or lose their ability to function, reducing overall visual function.
Are there other types of MacTel?
Yes, but they are even rarer than MacTel Type 2.
– MacTel Type 1 is a congenital disease that only occurs in males and usually in just one eye. Type 1 may be associated with Coat’s disease, which is a rare retinal disorder.
– MacTel Type 3 is less understood in the scientific community and is classified as a predominantly vascular disease of the retina, where diseased blood vessels tend to become closed or obstructed (“occluded”).
What are the symptoms of MacTel?
MacTel Type 2 usually affects both eyes. Patients usually report the following symptoms (though some do not experience any or all of these):
– Slow loss of vision over a prolonged period
– Blurry or distorted vision: Straight lines appear wavy, or there is a distinct “spot” (called a “scotoma”) of worse vision in the center of the visual field
– Difficulty reading; identifying details; missing/skipping letters, parts of words, or numbers
How is MacTel diagnosed?
An ophthalmologist (eye doctor) can perform an eye examination to determine if you have MacTel. Retina specialists look for specific signs and changes in your eyes that may be detected by examining the back of your eye (“fundus”) with a bright light source (“fundoscopy”) as well as special cameras such as an Optical Coherence Tomograph (OCT). Different imaging techniques allow the doctor to take images of the retina without touching the eye. For a more precise evaluation of retinal and choroidal blood vessels, an eye test that uses a special dye (“fluorescein”) and camera may be used to obtain pictures of blood flow to the back of the eye (angiography).
Who gets MacTel and why?
The exact causes for developing MacTel are still unknown. The disease sometimes runs in families, and specific genetic mutations have been identified in some MacTel patients. Therefore, it is likely that genetics plays a role in the development of the disease. Overall, MacTel is believed to be a “complex” disease that is caused by a combination of genetic and environmental factors. Some studies have proposed an association between MacTel and increased weight, hypertension, and/or type 2 diabetes.
Most people with MacTel are first diagnosed in middle-age (around 40s-60s) and it is equally prevalent among both men and women.
Are there treatments or cures for MacTel?
There are currently no approved cures or treatments for MacTel that would reverse existing damage, slow progression of vision loss, or prevent symptoms. An ongoing Phase III clinical trial is evaluating the safety and efficacy of ciliary neurotrophic factor (CNTF) in MacTel. CNTF is a growth factor that promotes the survival of certain neuronal cell types. In the clinical trial, CNTF is delivered via an implant in the back of the eye. The results of this study should be known by early 2023.
Will I go completely blind?
No. MacTel can cause a significant loss of central vision (which is needed for activities like reading and driving) but does NOT cause complete or total blindness. Peripheral vision is usually not affected by MacTel.
What is the timeline for my vision loss?
MacTel usually is a slowly-progressing disease, vision loss spanning 10-20 years, or more. If you notice a sudden decline in vision, it is recommended that you contact your eye doctor, as complications of the disease such as the development of new, abnormal blood vessels (“neovascularization”), bleeding or swelling may occur, and these conditions may be treatable.
What is a “leak” in my eye?
Leakage of abnormal retinal blood vessels commonly occurs in MacTel,and may be assessed by your eye doctor with an eye test that uses a special dye (“fluorescein”) and camera to evaluate vessels in the retina and choroid (“angiography”). This fluid leakage is not usually associated with bleeding and is not treatable.
Are injections recommended? How often should I get them?
Previous studies have shown no benefit of anti-VEGF injections in the general MacTel population. (Anti-VEGF injections are medications that block a specific factor known to promote abnormal blood vessels growth). In rare cases, however, patients may develop abnormal new blood vessels (“neovascularization”) as a secondary complication of MacTel. These abnormal blood vessels may cause an increase in leakage, bleeding and swelling, leading to a decline in visual function. In these cases, treatment with anti-VEGF injections may be beneficial.
In the instances of treatments for active bleeding or swelling, your eye doctor will determine if and how many injections will be needed and will monitor your disease and treatment response.
Do vitamins help treat MacTel?
There is currently no evidence of vitamins or supplements (including serine and glycine) that prevent, slow the progression of, or reverse damage caused by MacTel. Further investigations are needed to determine if there may be any benefits from a supplementation with certain nutrients.
Does MacTel cause dry eyes?
There is currently no evidence that MacTel causes dry eyes or that dry eyes are a symptom of MacTel. Researchers are currently investigating whether certain nerves within the cornea (the clear front part of your eye that covers the iris/pupil and focuses light into your eye) are affected in MacTel, and further studies are needed to evaluate a potential link.
Is double vision a symptom of MacTel?
MacTel typically causes blurry or distorted vision but does not usually cause double vision.
Are “floaters” a symptom of MacTel?
“Floaters” are spots in your vision that may appear as black or gray dots or strings. Most floaters are simply flecks of vitreous gel (the material that fills the back of the eye) that break off in the back of our eyes. They are not associated with MacTel, but with aging.
Are ocular migraines a symptom of MacTel?
No, ocular migraines are not associated with MacTel.
Are macular holes a symptom of MacTel?
Sometimes MacTel patients may also have macular holes because MacTel can lead to a thinning of the retina.
Does glare from light affect MacTel?
Patients with MacTel may be more sensitive to glare. Furthermore, they may experience problems with adapting to changing light conditions, and they may have reduced contrast sensitivity. Some of these issues are believed to be associated with a loss of macular pigment in MacTel. Macular pigment protects the retina from harmful short wavelength (blue) lights, and may be thought of as our “natural sunglasses.”
Do cataracts or cataract surgery affect MacTel?
A cataract is when the lens of the eye (a clear structure behind the iris that focuses light on the retina) is clouded. When the lens is cloudy, it can cause double vision, blurred vision, glare, sensitivity to light, and poor night vision. Cataracts are quite common, especially after the age of 60, and progress as you age. Because both MacTel and cataracts impair vision, having both diseases can further degrade overall vision. Cataract surgery to remove and replace the cloudy lens will significantly improve vision in cases where the cataract is causing vision loss. Your eye doctor can evaluate the degree of clouding in your lens and determine if and when cataract surgery should be performed and whether removing the cataract would improve your vision.
Can stress affect MacTel?
There have not been any studies assessing the relationship between stress and MacTel.
Can MacTel patients also have other co-existing eye diseases that affect vision?
Yes, it is possible to have other eye diseases, in addition to MacTel, that also affect vision.
What is the prevalence of neuropathy in MacTel patients? Should I be tested for it?
The prevalence of neuropathy in MacTel patients is not fully understood. MacTel is a co-morbidity of a rare peripheral neuropathy (HSAN1). The incidence of neuropathy in the general MacTel population is currently being investigated. Assessment for peripheral neuropathy is currently not necessary for patients without the accompanying symptoms. If you are experiencing symptoms of peripheral neuropathy (numbness, tingling, pain, abnormal temperature or sensory sensations, or ulcers), it is recommended that you follow up with your health care provider.
If you are experiencing symptoms of peripheral neuropathy, make sure you tell the study team when you enroll in the MacTel Registry or on your annual follow-up calls.
What are the stages of MacTel Type 2? How do they differ?
Currently, the most widely used clinical staging system comprises five stages of MacTel and has been developed by Gas and Blodi. Staging is based on characteristics your eye doctor can see when examining the back of your eye (“fundus”) with a bright light source (“fundoscopy”). We currently differentiate between stages 1 to 4 without the development of abnormal new vessels (“neovascularization”) and stage 5 with neovascularization. Under Gass and Blodi staging, knowing the stage of your disease does not provide much insight into how you might expect your disease to progress.
Newer imaging technologies have given us more insight into parameters and markers that may define disease progression in MacTel and may lead to an update of the current staging system in the near future.
Why do my latest scans show no further degenerations but my vision and ability to read is worsening?
Retinal scans show structural changes in the back of the eye, but they cannot always assess function and explain why a patient perceives worsening vision. This may be due to limits of the resolution of the scan or it may be due to non-retinal factors, such as cataracts or dry eye syndrome, that impair visual function.
Functional measures such as reading or visual acuity testing may be used to quantify changes in visual function. Microperimetry, a functional exam that measures light sensitivity in the retina, may be used to determine changes in visual function more precisely, and may detect spots of worse vision (“scotomas”) within the central visual field.
How do MacTel patients adjust/compensate for vision loss?
There are a few ways people with all types of macular diseases can adapt to their changing vision.
1. Low vision rehabilitation & occupational therapy
Low vision rehabilitation is like any other kind of physical therapy in that it requires a specialist to train patients in strategies to improve their functioning. Occupational therapists, and especially low vision rehabilitation specialists, can recommend lifestyle changes, such as:
– How to adapt your home for safety and easy navigation
– Labeling medications or things that are small and/or difficult to see/read
– Improving lighting conditions at home or the workplace
– Instruction on using tools or devices to make tasks easier
2. Preferred Retinal Locus (PRL)
PRL involves shifting your vision slightly to see something more clearly. This type of shift often happens naturally, but low vision rehabilitation can help train a patient to do this more effectively.
3. Therapeutic devices
Sometimes the use of different types of tools or technologies are recommended by your health care provider. Some examples include:
– Prescription lenses
– Electronic and/or portable magnification devices
– “Text to voice” devices (including clocks, timers, blood pressure monitors, etc.)
– Color-coded organizers (especially for pill bottles)
– Wearable magnifying devices and telescopes
4. Support Groups & Counseling
Mental health is as important as physical health. Your health care provider or a low vision specialist may be able to provide you with resources and information on support groups for people with vision loss, or refer you to a therapist or counselor to address emotional concerns related to your diagnosis.