Dry Eye Syndrome — Symptoms, Causes & Treatment | MyMedicPlus

Dry eye syndrome (DES), also termed dry eye disease (DED), is a multifactorial ocular surface condition characterised by instability of the tear film and ocular surface inflammation — leading to symptoms of discomfort, visual disturbance, and potential damage to the ocular surface. It occurs when the eyes either produce insufficient aqueous tears (aqueous-deficient dry eye) or when tears evaporate too rapidly (evaporative dry eye — accounting for approximately 65-80% of cases). It is one of the most prevalent eye conditions worldwide, affecting an estimated 5-50% of the global population depending on diagnostic criteria and geography. Women are disproportionately affected (approximately 2:1 female-to-male ratio), and prevalence increases markedly with age — affecting up to 30% of adults over 50. Dry eye disease causes significant discomfort, ocular surface damage, impairment of visual acuity (particularly contrast sensitivity and reading performance), and measurable reduction in quality of life comparable to moderate-to-severe angina. The 2017 DEWS II (Dry Eye Workshop) report defines DED as 'a multifactorial disease of the ocular surface characterised by loss of homeostasis of the tear film, accompanied by ocular symptoms, in which tear film instability, hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles.'

Aqueous-deficient dry eye: reduced lacrimal gland secretion — primary Sjögren's syndrome (autoimmune exocrinopathy); secondary Sjögren's with rheumatoid arthritis, SLE, or other connective tissue disease; non-Sjögren's causes include age-related lacrimal gland atrophy, lacrimal gland obstruction (trachoma, pemphigoid, radiation), and reflex secretion loss from corneal nerve damage (post-LASIK, post-herpetic keratitis, neurotrophic keratopathy). Evaporative dry eye (most common — 65-80%): meibomian gland dysfunction (MGD — blockage and atrophy of the oil-secreting tarsal glands, causing an inadequate lipid tear film layer and accelerated evaporation); incomplete or infrequent blinking (screen use, reading, contact lens wear, Parkinson's disease); eyelid margin disease (anterior blepharitis, seborrhoeic dermatitis); eyelid abnormalities (lagophthalmos from facial palsy — nocturnal exposure keratopathy; ectropion). Risk factors — systemic: advancing age; female sex (androgens critical for lacrimal and meibomian gland function — oestrogen reduction post-menopause worsens DED); connective tissue diseases; rosacea (severe MGD); thyroid eye disease (proptosis, lid retraction); vitamin A deficiency; diabetes (autonomic neuropathy impairing lacrimal secretion). Medications: antihistamines (potent anticholinergic effect), tricyclic antidepressants, SSRIs, beta-blockers, diuretics, oral contraceptives, isotretinoin, and topical preservatives (benzalkonium chloride — paradoxically causes DED from frequent eye drop use). Environmental: low humidity (air conditioning, central heating, aircraft), prolonged screen use (reduced blink rate from 15 to 5 per minute), contact lens wear, smoke, wind exposure.

Dry eye disease produces a characteristic and often cyclical symptom pattern. Ocular discomfort: persistent burning, stinging, grittiness, sandiness, or a foreign body sensation — often described as 'sand in the eyes'; dryness; aching or soreness. Visual symptoms: blurred vision that fluctuates with blinking and temporarily improves on blinking (due to tear film instability across the corneal optical surface — reduced contrast and visual acuity between blinks); difficulty with sustained near tasks (reading, screen use, driving) due to progressive visual deterioration over a fixation period. Eye fatigue (asthenopia): heaviness, difficulty keeping eyes open, and eye strain during sustained visual tasks — a common reason for reducing reading time and screen exposure. Photophobia: light sensitivity from ocular surface inflammation and corneal nerve sensitisation — may cause significant functional disability in bright environments. Paradoxical epiphora (excessive watering): reflex tearing triggered by ocular surface irritation — patients report watery eyes despite having dry eye disease, which can mislead assessment. Eyelid symptoms: crusting and debris along the eyelid margin from abnormal meibomian gland secretion in MGD; meibomian gland plugging visible on slit-lamp. Symptom aggravation: prolonged screen use (blink rate suppressed to 5/min from 15/min), low humidity, wind, smoke, contact lens wear, reading, driving, and late afternoon/evening (tear volume declines throughout the day). Morning symptoms predominate in nocturnal lagophthalmos; end-of-day worsening suggests evaporative DED.

Dry eye diagnosis combines symptom questionnaires and clinical testing. Validated symptom questionnaires: the OSDI (Ocular Surface Disease Index — score 0-100; above 13 indicates mild DED, above 33 severe) and the DEQ-5 (Dry Eye Questionnaire-5) quantify symptom burden and guide treatment decisions. Slit-lamp biomicroscopy: assessment of tear film meniscus height, meibomian gland expression (quality of meibum — milky or toothpaste-like secretions indicate MGD), eyelid margin telangiectasia, blepharitis, conjunctival injection, and corneal surface. Tear film break-up time (TBUT): fluorescein instilled in conjunctival sac — patient blinks then maintains fixation; time to first dark break-up spot is measured; below 10 seconds indicates instability; below 5 seconds suggests significant evaporative disease. Corneal and conjunctival staining: fluorescein reveals corneal epithelial defects (punctate keratopathy — graded by Oxford or NEI scale); lissamine green stains devitalised conjunctival and corneal epithelium. Schirmer's test (with topical anaesthesia): filter paper strips placed in lower fornix for 5 minutes; below 5 mm wetting suggests aqueous-deficient DED. Osmolarity testing (TearLab): tear film hyperosmolarity above 308 mOsm/L, or inter-eye difference above 8 mOsm/L, is a reliable DED biomarker. Meibography (infrared transillumination imaging of eyelids): assesses meibomian gland morphology and dropout — quantified by Meiboscore; essential for grading MGD severity and planning treatment.

Treatment follows a stepwise approach based on DED severity (DEWS II grades 1-4). Step 1 — mild DED: preservative-free artificial tears (sodium hyaluronate 0.1-0.2%, carbomer gels, lipid-based drops for MGD — preservative-free formulations essential for frequent use; benzalkonium chloride preservative worsens DED); 20-20-20 rule during screen use; lid hygiene (warm compresses 5-10 minutes twice daily — heating meibum to 40-45°C liquefies secretions; digital lid massage expresses meibum); humidification; environmental modification. Step 2 — moderate DED: non-preserved lubricants PRN and nocturnal lubricating gel or ointment; cyclosporine A eye drops 0.05% twice daily (Restasis — reduces T-cell-mediated inflammation; onset 3-6 months; CEQUA 0.09% is a higher-concentration newer formulation); lifitegrast 5% twice daily (Xiidra — LFA-1/ICAM-1 antagonist; onset 6-12 weeks); omega-3 fatty acid supplements (1,000-3,000 mg EPA+DHA daily — modest evidence for MGD); professional thermal meibomian gland expression (LipiFlow device, intense pulsed light/IPL — for MGD; IPL also reduces inflammatory mediators on the eyelid margin). Step 3 — severe or Sjögren's-related DED: punctal plugs (silicone plugs occlude lower lacrimal puncta — retains tears on the ocular surface; effective for aqueous-deficient DED); autologous serum eye drops (15-50% — prepared from patient's own blood, containing EGF, vitamin A, TGF-beta, fibronectin — for severe neurotrophic or Sjögren's DED); scleral contact lenses (large-diameter gas-permeable lenses maintain a fluid reservoir over the cornea — highly effective for severe DED); systemic immunosuppression for Sjögren's DED (hydroxychloroquine, pilocarpine — systemic cholinergic stimulation of secretion, rituximab in selected refractory cases).

Untreated or inadequately managed dry eye disease causes progressive ocular surface damage. Punctate keratitis: breakdown of the corneal epithelium at individual cell level — detected by fluorescein staining; causes pain, photophobia, and reduced visual acuity as it disrupts the optical surface. Corneal ulceration: severe aqueous-deficient DED (particularly Sjögren's) can progress to sterile or infectious corneal ulceration — leading to corneal scarring, irregular astigmatism, and permanent visual impairment. Filamentary keratitis: strands of mucus and epithelial cells attach to the cornea causing severe pain and foreign body sensation — a debilitating complication of severe DED. Corneal neovascularisation and opacification: chronic ocular surface inflammation triggers vessel ingrowth into the normally avascular cornea, causing progressive opacity and visual loss. Increased infection risk: compromised epithelial barrier allows penetration of pathogens — microbial keratitis is a serious sight-threatening complication, particularly in contact lens wearers with DED. Quality of life and mental health impact: DED has a profound functional impact — driving, reading, digital device use, and social interaction are significantly restricted; DED is strongly associated with depression, anxiety, and suicidal ideation in severe cases, comparable in impact to moderate angina or dialysis. DED creates a chronic cycle where inflammation causes neural sensitisation, which amplifies pain and perpetuates further inflammation and ocular surface damage even without ongoing exogenous triggers.

Follow the 20-20-20 rule during screen use: every 20 minutes, look at an object 20 feet (6 metres) away for 20 seconds — this restores normal blink rate and allows the tear film to stabilise. Make a conscious effort to blink fully and frequently during screen work. Use a humidifier in dry environments (particularly offices, aircraft, and centrally heated rooms); target indoor relative humidity of 40-50%. Wear wraparound sunglasses or moisture chamber goggles outdoors in windy or dusty conditions to reduce evaporation. Maintain good lid hygiene: warm compresses to the closed eyelids for 5-10 minutes twice daily and gentle digital lid massage reduce MGD and meibomian gland dysfunction. Limit contact lens wearing time; choose daily disposable lenses over extended-wear; ensure lenses are replaced as scheduled; remove before sleeping. Stay well hydrated (at least 2 litres of fluid daily). Avoid prolonged exposure to air conditioning or heating vents directed at the face. Review medications with a doctor if dry eyes are a suspected side effect (antihistamines, antidepressants, diuretics — alternatives or dose adjustments may help). Omega-3 fatty acids (oily fish, flaxseed, or supplements) support meibomian gland function. For contact lens wearers: always wash hands before handling lenses and use preservative-free lubricating drops compatible with lens wear.

See an optometrist or GP for: persistent eye dryness, grittiness, or burning that is not adequately relieved after 2-4 weeks of regular artificial tear use; eyes that water excessively (reflex tearing from dry eye — often misidentified as 'too wet' rather than dry); symptoms significantly affecting reading, screen use, or driving. Seek urgent ophthalmological assessment for: sudden marked reduction in vision; eye pain (rather than irritation or discomfort — pain suggests corneal involvement); visible corneal cloudiness or whitening; red, very painful eye associated with photophobia (light sensitivity); or dry eyes in a person with rheumatoid arthritis, Sjogren's syndrome, or lupus who develops new rapidly worsening eye symptoms. Dry eyes from contact lens wear require a specialist contact lens review — continuing to wear ill-fitting lenses in dry eye worsens corneal damage. If prescribed topical steroids or ciclosporin eye drops for dry eye, attend follow-up appointments as scheduled to monitor intraocular pressure.