Dry-eye disease and blepharitis

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

The tear film supplies a smooth optical surface and protects the corneal epithelium. Dry-eye disease develops when tear production, distribution or retention becomes inadequate. Reduced aqueous secretion, increased evaporation and incomplete blinking often coexist. A patient may describe grittiness late in the working day, intermittent difficulty focusing or watering outdoors. Reflex tears do not necessarily restore an effective film. Ask about the timing of symptoms, whether blinking clears the blur, and the effect on reading, driving, sleep and employment.

Blepharitis is chronic inflammation around the lid margins. Anterior disease involves the lashes and their roots; posterior disease involves meibomian gland dysfunction with abnormal lipid secretion. Examine the lashes, gland openings, blink completeness and lid position as well as the conjunctiva and cornea. Rosacea and seborrhoeic skin disease can contribute. Screens, air conditioning, smoking, contact lenses and some medicines aggravate symptoms. Review a potentially contributory medicine with its prescriber instead of advising abrupt withdrawal of essential treatment.

Effective treatment is usually a repeatable routine rather than a single short prescription. Agree a manageable combination of lubrication, twice-daily lid care when indicated and changes to drying exposures. Demonstrate each technique. Apparent treatment failure can reflect insufficient lid warming, difficulty delivering drops, irritation from preservatives or an alternative diagnosis. Persistent troublesome symptoms after a few weeks merit reassessment; the appearance of severe pain, marked light sensitivity or enduring visual change requires earlier action.

Key points

Dry eye reflects unstable tear-film function and surface inflammation; reflex watering can occur despite inadequate lubrication.
Meibomian gland dysfunction promotes evaporation and often links posterior blepharitis with dry-eye symptoms.
Burning, grittiness and fluctuating blur that clears after blinking fit surface disease, but sustained visual loss requires further assessment.
Lid cleaning should continue regularly after improvement because blepharitis commonly recurs when maintenance stops.
Combine environmental changes, sustained lid care and suitable lubrication, then review response and administration technique.
Refractory disease needs diagnostic reassessment rather than repeated unsupervised antibiotic or steroid courses.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Evaporation and gland dysfunction

Altered meibomian lipid secretion allows tears to evaporate more readily. Incomplete blinking, dry air and contact-lens wear can add further stress to the ocular surface.

Reduced aqueous secretion

Ageing, medicines and lacrimal dysfunction can reduce tear production. Sjögren syndrome and other inflammatory disorders deserve consideration when marked ocular dryness accompanies persistent oral dryness.

Lid and skin inflammation

Lash-margin bacterial burden, seborrhoeic changes and rosacea can contribute to blepharitis. These recurrent processes interact with the tear film rather than necessarily causing an isolated acute infection.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Unstable optical surface
A rapidly breaking or uneven tear film loses its optical smoothness and protective function. Vision fluctuates and epithelial cells experience greater drying between successive blinks.
2
Inflammatory feedback
Hyperosmolarity and epithelial stress promote inflammatory signalling that can further disturb surface function. Symptoms may persist after the initial drying exposure has been reduced or removed.
3
Reflex tearing
Sensory stimulation from the irritated surface can cause excessive watery tears. This response does not necessarily restore adequate lipid distribution or normal spreading across the cornea.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Tear-film instability

Burning, foreign-body sensation and variable blur during reading or screen work suggest surface instability, especially when blinking briefly improves vision.

Lid-margin inflammation

Crusts at lash roots, irritated lid edges and sticking on waking support blepharitis; plugged meibomian openings suggest a posterior component.

Exposure and mechanics

Incomplete lid closure, reduced blinking, ectropion or prominent eyes can prevent adequate surface protection and require more than additional daytime drops.

Systemic clues

Persistent oral dryness, dental problems, inflammatory joint symptoms or autoimmune disease raise concern for reduced tear production associated with systemic illness.

Red flags requiring action

Persistent visual loss, a corneal white spot or severe unilateral pain requires urgent corneal assessment.
A newly painful red eye in a contact-lens wearer needs same-day specialist triage.
Severe ocular dryness with mouth dryness, joint symptoms or other systemic features requires assessment for an associated disorder.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Visual acuity with usual correctionFirst step
Why
Determine whether symptoms accompany a sustained functional deficit.
Interpretation and limitations
Acuity may fluctuate with tear-film quality, but a persistent reduction needs further ocular assessment rather than automatic attribution to dryness.
02
Lid and surface examination
Why
Identify gland dysfunction, lash debris and exposure mechanisms.
Interpretation and limitations
Lid-margin findings guide routine treatment; a focal corneal opacity, ulcer or marked unilateral inflammation changes the urgency and differential diagnosis.
03
Fluorescein and tear-film assessment
Why
Assess epithelial injury and tear-film stability when trained.
Interpretation and limitations
Punctate epithelial staining can accompany dryness, whereas a focal ulcer or dendritic lesion requires another explanation and specialist management.
04
Selective tear-production and systemic tests
Why
Investigate suspected aqueous deficiency or associated systemic disease.
Interpretation and limitations
Schirmer testing and targeted autoimmune assessment may help selected patients; uncomplicated brief irritation does not require an indiscriminate blood-test panel.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Allergic conjunctivitis

Prominent itch, a seasonal relationship and rhinitis favour allergy. Allergy can coexist with dryness, but increasing lubricants alone may leave the allergic process inadequately treated.

Microbial keratitis

A focal opacity, significant pain, photophobia or sustained acuity loss needs assessment for infection. An existing dry-eye diagnosis does not lower the urgency of these findings.

Exposure keratopathy

Poor lid closure or abnormal lid position leaves the cornea exposed, particularly during sleep. Identifying the mechanical problem matters because ordinary daytime drops may provide insufficient protection.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Surface protectionImprove lubrication and support normal blinkingFirst stepSymptoms and examination support dry eye without urgent corneal or visual findings.

1Choose a lubricant suitable for symptom severity and practical administration, explaining dose, expiry and storage.
2Encourage screen breaks, a screen slightly below eye level and avoidance of direct airflow or smoke where feasible.
3Review inadequate improvement after a few weeks, checking formulation tolerance, blink function and whether the diagnosis still fits.

02Lid careMake treatment a sustainable daily routineLash debris, lid irritation or meibomian gland dysfunction accompanies the ocular discomfort.

1Apply a comfortably warm clean compress over closed lids for five to ten minutes without using heat that could burn.
2Massage the closed lids gently for about thirty seconds, then carefully clean the lid margins with an appropriate clean pad or product.
3Repeat lid care twice daily and continue after improvement; avoid eye makeup and contact lenses while the lids are actively inflamed.

03ReassessmentIdentify the reason symptoms remain troublesomeAn adequate treatment routine has not controlled symptoms or examination suggests significant surface disease.

1Check for allergy, rosacea, exposure, medication toxicity and aqueous deficiency before simply increasing preserved drops.
2Seek optometric or ophthalmic assessment for persistent disease, corneal staining or treatment that may require anti-inflammatory medication.
3EscalationEscalate urgently for new pain, photophobia or visual loss, and arrange medical investigation when systemic autoimmune symptoms are present.

Key medicines and prescribing safety1 treatment · regimens, roles and cautions

Provides lubrication for symptoms caused by insufficient or unstable tear-film function.

Carmellose sodium eye drops

Instil one to two drops into the affected eye or eyes as needed. The NHS describes 0.5% for mild symptoms and 1% for moderate to severe symptoms; treatment can continue for as long as needed.

Follow product-specific contact-lens and opening-expiry instructions. Consider preservative-free drops for frequent use or intolerance. Leave at least five minutes between different drops, and apply ointment after drops.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Corneal epithelial damage

Severe tear deficiency or exposure can cause epithelial breakdown. Increasing pain, a substantial defect or an infiltrate requires assessment for infection and progressive tissue damage.

Recurrent gland obstruction

Meibomian obstruction may lead to chalazia, while inflamed lids remain uncomfortable. A recurrent or atypical focal lesion deserves examination rather than automatic attribution to routine blepharitis.

Reduced everyday function

Unstable vision and discomfort can impair sustained reading, computer work and driving confidence. Treatment review should measure these effects alongside the appearance of the ocular surface.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Review symptom burden and reading tolerance alongside examination, because visible redness alone does not measure the effect on daily life.
Ask the patient to demonstrate lid care and drop administration before concluding that an appropriate treatment has failed.
Check whether preserved drops cause immediate irritation and whether another formulation or a preservative-free product would be more suitable.
Review opening dates and storage; single-dose vials and multidose bottles have different product-specific discard instructions.
Refer persistent troublesome symptoms after several weeks, with immediate reassessment for a painful red eye, significant photophobia or sustained visual decline.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Watering does not exclude dryness

An irritated surface may produce reflex tearing that fails to correct lipid abnormalities or poor tear spreading, so visible watering can coexist with dry-eye disease.

Symptoms and signs may differ

Severe discomfort can occur with limited staining, while reduced corneal sensation can conceal substantial epithelial damage. Combine the symptom history with an appropriate examination.

Explain warming clearly

A briefly applied cool cloth may provide inadequate warming, while excessive heat can burn. Agree a safe and sustainable technique that fits the patient's circumstances.

Escalation needs a defined indication

Selected refractory lid disease may warrant antibiotics, and significant inflammatory surface disease may need specialist anti-inflammatory treatment. Neither should replace reassessment of diagnosis, technique and contraindications.

11Common pitfallsFrequent interpretation and management errors.

01
Prescribing antibiotics for every recurrence of lash crusting while omitting a maintenance lid-care plan.
02
Reassuring about persistent visual loss simply because the patient already has a dry-eye diagnosis.
03
Continuing to add preserved drops without asking about irritation, delivery technique or an alternative explanation.
04
Starting ocular steroids without a defined indication, exclusion of relevant infection and an ophthalmic monitoring plan.