Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is a neurological illness, so it is not surprising that it can cause a wide variety of visual disturbances. Most of them are not caused by damage to the eyes, but rather by neurological or neuromuscular problems.
For some reason these symptoms are not often discussed, often causing needless worry in patients. In a small study of 25 patients with CFS/ME all reported ocular (eye) symptoms (Caffery et al.).
It is still important to note the possibility of misdiagnosis or a coexisting illness. Blurred vision may be caused by diabetes or pituitary tumors, which can also mimic other symptoms of CFS/ME. Optic neuritis is not typical of CFS/ME and suggests multiple sclerosis. A typical sign of optic neuritis is changes in color vision. It can also cause sudden complete loss of vision.
Hypothyroidism can lead to dry eyes and occasionally Graves' opthtalmopathy, which may be associated with bulging eyes. Dry eyes may be a sign of Sjögren's syndrome, with other symptoms which can also resemble those of CFS/ME
Many anticonvulsants and antidepressants and some other drugs can cause transient vision disturbances. Antimalarial/antirheumatic drug hydroxychloroquine and anticonvulsant vigabatrin may both permnently damage vision, but are rarely used in CFS/ME.
Vision Disturbances in CFS/ME
Photophobia is not a real phobia (fear), but refers to light sensitivity of the eyes. It is very common in CFS/ME. This association is described in detail in this article. On the other hand, night vision may also suffer in CFS/ME.
Double vision and trouble focusing are also common in CFS/ME. Fatigue often makes this problem worse, but it may be present at rest, too. Rarely patients may even completely lose the ability to read or watch television because of this. Attempting to focus may lead to vertigo and nausea.
Patients may also have nystagmus, which is an outwardly visible involuntary movement of the eyes. It may develop with fatigue or eye strain.
A more peculiar, uncommon vision disturbance is "tunnel vision". Less severe loss of peripheral vision is also possible. Rarely color acuity may be decreased and even color blindness may develop. These are rarely listed as symptoms of CFS/ME, but are reported in the reference by Anil Jain and renowned CFS/ME expert Byron Hyde.
Patients may also have problems with visual comprehension, such as having problems intepreting the colors of traffic lights correctly, despite normal color vision. Spatial and depth perception may suffer. Patients may walk into walls and door frames and may have trouble climbing stairs because of visual dysfunction. Some even report that objects like stairs appear to "repeat" themselves, making it difficult to judge when they end.
Jain and Hyde also report four instances of visual reversals, usually temporary – left and right or up and down switching places.
Other Eye Complaints in CFS/ME
While dry eyes can signal hypothyroidism or Sjögren's syndrome, they are also common in CFS/ME by itself. This symptom is called keratoconjuctivitis sicca or sicca syndrome. The dryness can cause itching and a "sandy" feeling in the eyes, redness, tearing, vision strain and mild vision disturbances, even eye pain.
Many medications commonly used in CFS/ME can also cause dry eyes, especially antihistamines, anticholinergic drugs and tricyclic antidepressants like amitriptyline.
Some people with CFS/ME have eye pain which is not due to dry eyes, but the reason often remains unclear. Nonetheless, it is well known that CFS/ME can cause pain in unusual locations.
Many patients have abnormally large pupils, which may explain the photophobia. Some report that many medications cause their pupils to greatly enlarge especially when initiating use. Anisocoria. (asymmetrically sized pupils) and other abnormalities in pupil size, including a "cogwheel" movement of the pupil and even dilatation (as opposed to contraction) in response to light have also been reported.
Treatments for Eye Symptoms
For most eye symptoms the treatment is symptom-based. For example, using sunglasses or dimming the lights may alleviate discomfort in cases of photophobia. Artificial tears or medication changes may relieve eye dryness.
The muscle relaxant baclofen may relieve nystagmus and other neuromuscular eye symptoms (Comer et al.). The herb Siberian ginseng or eleuthero (Eleutherococcus senticosus) has been reported to improve light and color perception in healthy persons (Arushanian et al.).
References
Caffery BE, Josephson JE, Samek MJ. The ocular signs and symptoms of chronic fatigue syndrome. J Am Optom Assoc. 1994 Mar;65(3):187-91.
Hyde B, Jain A, Clinical Observations of Central Nervous System Dysfunction in Post-Infectious, Acute Onset M.E./CFS. In the book: Hyde B (ed.) The Clinical and Scientific Basis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. The Nightingale Research Foundation 1992. pp. 48-51.
Comer RM, Dawson EL, Lee JP. Baclofen for patients with congenital periodic alternating nystagmus. Strabismus. 2006 Dec;14(4):205-9.
Arushanian EB, Shikina IB. [Improvement of light and color perception in humans upon prolonged administration of eleutherococcus]. Eksp Klin Farmakol. 2004 Jul-Aug;67(4):64-6.
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