Dry eye syndrome (DED) may be among the causes of Chronic Fatigue Syndrome (CFS). This is the finding of a study conducted in Taiwan on almost 900 DED patients.
Chronic fatigue syndrome: what it is
Chronic fatigue syndrome is a complex disorder that negatively affects quality of life. CFS is characterised by severe and disabling fatigue and other symptoms, including muscular and skeletal pain, sleep disturbances, reduced concentration and headaches. It is a long-term and persistent condition that is difficult to diagnose, in which fatigue persists even after periods of rest. The underlying factors of this condition are not yet known, and several studies have been devoted to understanding the aetiology of CFS.
CFS and dry eye syndrome, a possible correlation?
La dry eye syndrome (DED) is a multifactorial disorder of the ocular surface, characterised by impairment and loss of tear film homeostasis and ocular surface dryness and pain. Several studies have shown that CFS is often related to dry eye symptoms and the Sjögren's syndrome. In particular, a clinical study reported that symptoms of dryness were present in about 70% of patients with chronic fatigue syndrome. However, the relationship between DED and the risk of developing CFS is still not well defined. Therefore, a study conducted in Taiwan sought to shed light on the correlation between chronic fatigue syndrome and dry eye syndrome.
The results of the study
I results of the Taiwanese study have shown that patients with any comorbidity have an increased risk of developing CFS. Moreover, being affected by a severe form of DED appears to be directly related to the development of CFS.
In particular, patients with dry eye syndrome showed a 2-fold higher risk of developing CFS, compared to the control group without DED. The risk remained higher (approximately 1.6-fold) even after normalising the data for age, gender and comorbidities.
The study also examined the correlation between the frequency of DED-related doctor visits and the risk of developing chronic fatigue syndrome. The results showed that those who visit a specialist once or twice a year for dry eye syndrome run an almost five times higher risk of developing CFS in their lifetime. Essentially, the results showed that the cumulative incidence rate of developing chronic fatigue syndrome was significantly higher in the group of patients with DED, compared to patients without dry eye syndrome. In addition, the cumulative incidence rate of CFS increases with follow-up time, so the condition may also occur later in life compared to DED.
According to the researchers, the possible correlation between dry eye syndrome and chronic fatigue syndrome could reflect a dysfunction of the immune system, further complicated by the presence of chronic diseases. CFS would, therefore, be a complication of these conditions. Indeed, dysregulated ocular immune responses cause damage to the ocular surface and are one of the factors contributing to the pathogenesis of DED.
Conclusions
In conclusion, the study results showed that the risk of developing chronic fatigue syndrome is associated with both dry eye syndrome and other comorbidities. Moreover, the onset of DED also seems to be correlated with the incidence of CFS in later life years. Therefore, DED could also be considered as a marker in clinical practice to improve the diagnosis of CFS, which to date is still based on patient-reported symptoms.
The researchers also recommend that physicians take adequate account of the increased risk of chronic fatigue syndrome among patients with dry eye syndrome and adequately assess the impact of these conditions on patients' general health.
- Chen CS, Cheng HM, Chen HJ, Tsai SY, Kao CH, Lin HJ, Wan L, Yang TY. Dry eye syndrome and the subsequent risk of chronic fatigue syndrome-a prospective population-based study in Taiwan. Oncotarget. 2018 Jul 17;9(55):30694-30703.
- Cleare AJ, Reid S, Chalder T, Hotopf M, Wessely S. Chronic fatigue syndrome. BMJ Clin Evid. 2015 Sep 28;2015:1101. PMID: 26415100; PMCID: PMC4585442.
- Periman LM, Perez VL, Saban DR, Lin MC, Neri P. The Immunological Basis of Dry Eye Disease and Current Topical Treatment Options. J Ocul Pharmacol Ther. 2020 Apr;36(3):137-146.