TABLE 1.
Characteristics of the Study Population
| All (N = 85,302) | Men (N = 34,963) | Women (N = 50,339) | |
| Age, yr, mean (SD) | 50.7 (12.4) | 51.6 (12.5) | 50.1 (12.3) |
| Ethnicity—White, European, % | 98.6% | 98.8% | 98.4% |
| Income | |||
| <2000 Euro per mo | 27.3% | 21.6% | 31.2% |
| 2000–3000 Euro per mo | 29.6% | 33.1% | 27.2% |
| >3000 Euro per mo | 33.1% | 37.6% | 30.0% |
| Chose not to answer | 10% | 7.7% | 11.6% |
| Smoker | |||
| Current | 15.6% | 17.0% | 14.6% |
| Former | 33.3% | 35.7% | 31.2% |
| Never | 51.1% | 47.3% | 54.2% |
| Dry eye | |||
| WHS definition, % | 9.0% | 5.0% | 11.9% |
| Highly symptomatic dry eye, % | 1.9% | 0.9% | 2.6% |
| Clinical diagnosis | 8.4% | 4.6% | 11.1% |
| Symptomatic dry eye, % | 30.0% | 22.4% | 35.3% |
| Comorbidities* | |||
| No. comorbidities, mean (SD) | 2.9 (2.1) | 2.3 (1.8) | 3.2 (2.3) |
| Presence of ≥1 comorbidity | 88.9% | 85.0% | 91.7% |
| Caffeine intake | |||
| Caffeine intake, mg/d, mean (SD) | 285 (182) | 339 (190) | 249 (167) |
| High caffeine intake (≥400 mg/d), % | 24.7% | 35.1% | 17.5% |
| Coffee consumption | |||
| Coffee intake, cups/d, mean (SD) | 3.4 (2.2) | 4.1 (2.2) | 3.0 (2.0) |
| Intake of ≥1 cup/d of coffee | 83.9% | 90.8% | 79.1% |
| Tea consumption (N = 82,170) | |||
| Tea intake, cups/d, mean (SD) | 2.1 (2.0) | 1.4 (1.6) | 2.5 (2.1) |
| Intake of ≥1 cup/d of tea | 61.1% | 46.0% | 71.3% |
| Cola consumption (N = 79,957) | |||
| Cola intake, glass/d, mean (SD) | 0.3 (0.8) | 0.4 (0.9) | 0.3 (0.7) |
| Intake of ≥1 cup/d of colas | 10.2% | 13.8% | 7.6% |
| Energy drink consumption (N = 73,938) | |||
| Energy drink intake, glass/d, mean (SD) | 0.01 (0.1) | 0.02 (0.1) | 0.01 (0.1) |
| Intake of ≥1 cup/d of energy drinks | 0.2% | 0.3% | 0.2% |
Contact lens wear, hypertension (measured), macular degeneration, glaucoma/ocular hypertension, eye surgery (any), allergic conjunctivitis, Bell palsy, keratoconus, laser refractive surgery, irritable bowel syndrome, fibromyalgia, osteoarthritis, spinal disc herniation, repetitive strain injury, rheumatoid arthritis, systemic lupus erythematosus, Sjogren disease, atherosclerosis, cardiac arrhythmia, liver cirrhosis, chronic cystitis, urinary incontinence, spasticity, migraine, chronic fatigue syndrome, depression, burnout, autism, gastric ulcer, Crohn's disease, asthma, acne, psoriasis, eczema, rosacea, hay fever, allergy (any), anemia, diabetes mellitus, osteoporosis, thyroid disease (any), Graves disease, carpal tunnel syndrome, obstructive sleep apnea, lichen planus, sarcoidosis, chronic back pain, or sinusitis.