Dry Eye Syndrome — Causes, Symptoms, Diagnosis & Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Dry eye disease (DED), also called dry eye syndrome (DES) or keratoconjunctivitis sicca (KCS), is a multifactorial disease of the ocular surface characterised by a loss of homeostasis of the tear film, accompanied by ocular symptoms, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles (TFOS DEWS II definition, 2017). The tear film has three layers: outer lipid (meibomian glands), middle aqueous (lacrimal glands), and inner mucin (goblet cells). Disruption of any layer causes dry eye. It is classified as aqueous-deficient (insufficient lacrimal gland production) or evaporative (excessive tear evaporation — most common, usually from meibomian gland dysfunction). DED is one of the most prevalent eye conditions globally, affecting 5-50% of adults depending on population and diagnostic criteria used.

Evaporative dry eye (most common — 85% of dry eye): meibomian gland dysfunction (MGD — blockage/inflammation of oil-secreting glands of the eyelids leading to poor-quality lipid layer and increased tear evaporation); incomplete blinking (from screen use, reading — reduces blink rate from 15/min to 5/min); contact lens wear; low-humidity environments; air conditioning; wind. Aqueous-deficient dry eye: Sjogren's syndrome (autoimmune — lacrimal and salivary gland destruction; primary or secondary to RA, SLE, systemic sclerosis); non-Sjogren's: age-related lacrimal gland atrophy, lacrimal gland ablation, medications (antihistamines, tricyclic antidepressants, isotretinoin, diuretics, beta-blockers, antipsychotics — all reduce aqueous tear production). Risk factors: female sex (hormonal influences — oestrogen deficiency post-menopause), advancing age, Asian ethnicity, prior refractive surgery (LASIK disrupts corneal nerves), vitamin A deficiency, prolonged digital screen use, and autoimmune diseases.

Classic symptoms include a foreign body or gritty sensation ('as if there is sand in the eye'), burning or stinging, dryness, photophobia, intermittent or constant blurred vision (improves briefly with blinking — tear film instability), excessive watering (paradoxical reflex tearing from irritated cornea), eye fatigue, and difficulty wearing contact lenses. Symptoms typically worse at end of day, in dry or air-conditioned environments, after prolonged screen use, and in outdoor wind exposure. The OSDI (Ocular Surface Disease Index) and DEQ-5 questionnaires quantify symptom severity. Severe dry eye can cause corneal punctate epithelial erosions, filamentary keratitis, corneal ulceration (rare), and — in aqueous-deficient dry eye — significant visual impairment. Sjogren's syndrome-associated dry eye is usually more severe.

Diagnosis combines validated symptom questionnaires with clinical tests. Schirmer's test: filter paper placed in the lower conjunctival fornix — normal wetting is above 10 mm in 5 minutes; below 5 mm indicates severe aqueous deficiency. Tear break-up time (TBUT): fluorescein instilled; time from blink to first dry spot on corneal surface — below 10 seconds indicates evaporative dry eye or tear film instability. Ocular surface staining: sodium fluorescein (corneal epithelial defects — punctate staining); lissamine green or rose bengal (conjunctival damage). Meibomian gland assessment: slit-lamp examination of meibomian gland orifices and expression of meibum quality; meibography (infrared imaging of meibomian glands — detects gland dropout and atrophy). Tear osmolarity (TearLab): above 308 mOsm/L confirms hyperosmolarity; above 316 mOsm/L or 8 mOsm/L intereye difference is diagnostic. Autoimmune blood tests (ANA, anti-Ro/SSA, anti-La/SSB, RF) for suspected Sjogren's syndrome.

Lubricating eye drops (artificial tears): cornerstone of mild-moderate DED — used as frequently as needed (up to 4-6 times daily for moderate disease); preservative-free drops are essential for frequent use (preserved drops cause toxicity to corneal epithelium with more than 4 applications daily); formulations: hyaluronic acid (Hylotears, Optive), carbomer gels (Viscotears — longer contact time), liposomal sprays for lipid layer replenishment. Lid hygiene for MGD: warm compresses (45°C for 10 minutes) to melt thickened meibum; lid massage and cleaning with diluted baby shampoo or commercially available lid wipes. Anti-inflammatory therapy: cyclosporin 0.1% (Ikervis — NICE-approved) is the most evidence-based prescription treatment for moderate-severe dry eye with ocular surface inflammation — increases goblet cell density and reduces inflammatory cytokines; takes 3-6 months for full effect. Oral omega-3 fatty acids (fish oil supplements): modest evidence for MGD and evaporative dry eye — may reduce meibomian gland inflammation. Punctal plugs: silicone plugs inserted into lacrimal puncta to reduce tear drainage — effective for aqueous-deficient DED. Intense pulsed light (IPL) therapy: treats MGD by reducing lid surface inflammation and expressed meibomian gland secretions — evidence of sustained benefit in multiple RCTs. Autologous serum eye drops: prepared from patient's own blood serum; highly effective for severe or Sjogren's-associated DED — contains growth factors and vitamin A to promote epithelial healing. Scleral contact lenses: for severe DED with corneal involvement — provide a fluid reservoir over the ocular surface. Treat Sjogren's syndrome systemically.

Severe or inadequately treated dry eye can progress beyond discomfort to cause ocular surface damage. Recurrent punctate epithelial erosions from corneal surface desiccation can coalesce into frank corneal ulceration, particularly in Sjogren's syndrome-associated severe aqueous-deficient dry eye. Filamentary keratitis (mucus strands and epithelial cells adhering to the corneal surface) causes severe pain, photophobia, and visual disruption resistant to standard lubricant therapy. Corneal perforation is a rare but recognised complication of very severe dry eye with neurotrophic keratopathy, following refractive surgery (LASIK-induced neurotrophic keratopathy), or in Stevens-Johnson syndrome. Contact lens intolerance — permanent loss of ability to wear contact lenses from persistent surface disruption — occurs in severe DED. Microbial keratitis risk is significantly elevated in dry eye contact lens wearers: Pseudomonas aeruginosa and Acanthamoeba can cause vision-threatening corneal infections. Chronic pain, photophobia, and visual fluctuation significantly impair quality of life, work performance, and mental health in moderate-to-severe DED.

Apply the 20-20-20 rule for screen use: every 20 minutes, look at something 20 feet away for 20 seconds — reduces digital eye strain and blink frequency reduction. Blink consciously and completely during screen use. Optimise workstation ergonomics: position screen below eye level (reduces exposed ocular surface area). Use a humidifier in dry indoor environments (target 40-60% humidity). Avoid air conditioning and fans directed at the face. Wear wraparound glasses or goggles outdoors in windy conditions. Remove eye makeup thoroughly — eye makeup particles can block meibomian gland orifices. Stay well hydrated (dehydration reduces tear production). Use preservative-free eye drops proactively before activities that trigger symptoms. Omega-3 supplement (1-2 g EPA/DHA daily) for prevention in high-risk groups.

See an optometrist or ophthalmologist for persistent eye dryness, gritty sensation, burning, or blurred vision that does not improve with over-the-counter artificial tears, or that is interfering with daily activities or quality of life. Seek urgent eye care for: sudden vision loss, severe eye pain, significant eye redness with discharge (possible corneal infection), or any corneal injury — do not use dry eye drops as the sole treatment for these symptoms. Dry eye with dry mouth, fatigue, and joint pain suggests Sjogren's syndrome — seek GP assessment and rheumatology referral. Contact lens wearers with persistent discomfort should have a contact lens assessment and consider temporary discontinuation.