Ophthalmia neonatorum from Neisseria gonorrhoeae is a true ocular emergency — neonatal gonorrhoeal conjunctivitis can cause corneal ulceration, perforation, and permanent blindness within 24-48 hours if untreated. The clinical features: onset within the first 1-5 days of life (reflecting intrapartum transmission through infected birth canal), marked bilateral lid swelling (chemosis), profuse purulent discharge, and corneal haziness if advanced. Any neonate with a discharge-producing red eye in the first 5 days of life requires same-day ophthalmology referral and immediate gram stain/culture (gram-negative intracellular diplococci in the discharge = gonorrhoea until proved otherwise). Treatment: ceftriaxone 25-50 mg/kg IV or IM single dose (for gonorrhoea) + saline eye irrigation. Topical antibiotics alone are inadequate — systemic treatment is mandatory. Chlamydial ophthalmia neonatorum (onset days 5-14) must also be treated systemically (oral erythromycin syrup 12.5 mg/kg QDS for 14 days in neonates, or azithromycin) to prevent Chlamydia pneumonitis, which can develop even after successful treatment of the conjunctivitis.

The paradox of dry eye causing watery eyes is one of the most important conceptual points in eye examination — and the reason why many patients with epiphora do NOT have overflow of tears due to obstruction or allergy, but rather have dry eye disease causing reflex hyperlacrimation. When the tear film is unstable (as in evaporative dry eye from meibomian gland dysfunction), the corneal surface rapidly desiccates between blinks. The corneal dryness triggers a trigeminal reflex arc that stimulates the lacrimal gland to produce an acute watering episode — often described by patients as 'my eyes water when I go outside or into a cold wind' or 'my eyes are dry and then suddenly water.' This reflex tear is watery and low-quality (lacking the lipid layer from meibomian glands) and provides only temporary relief. Asking three questions distinguishes dry eye epiphora from drainage obstruction epiphora: (1) Is it worse in wind or cold? (dry eye — evaporation); (2) Does it improve when blinking (dry eye — redistribution of tear film); (3) Is there gritty or burning sensation (dry eye) vs painless constant overflow (drainage obstruction)?

The fluorescein dye disappearance test (DDT) is a simple, rapid primary care test that can objectively assess nasolacrimal drainage without specialist equipment — instil a drop of fluorescein (from a fluorescein strip or preservative-free fluorescein 2% drops) into the inferior fornix of each eye simultaneously, then assess the remaining fluorescein under a cobalt blue light (or standard ophthalmoscope) at 5 minutes. Normal: minimal fluorescein residue bilaterally (most has drained via the nasolacrimal duct). Obstruction: fluorescein remains in the tear lake/inferior fornix unilaterally or bilaterally. The test is particularly useful in: assessing the severity of CNLDO in infants (more fluorescein retention = more significant obstruction, less likely to resolve spontaneously), monitoring response to massage in CNLDO (improving drainage = less retention over weeks), and objectively confirming drainage failure before ophthalmology referral for dacryocystorhinostomy (DCR).

Meibomian gland dysfunction (MGD) is the most common cause of dry eye disease and the most common cause of blepharitis in the UK — meibomian glands are sebaceous glands embedded in the tarsal plate of the eyelids that secrete the lipid layer of the tear film. In MGD, the gland orifices become occluded by inspissated (thickened, waxy) secretions, reducing lipid secretion into the tear film and causing rapid tear film evaporation. The lipid deficiency leads to an unstable tear film, corneal desiccation between blinks, and the paradoxical watery eye. The treatment is mechanical: warming the eyelids (hot compress for 10 minutes twice daily — softens the inspissated meibomian secretions) followed by lid massage (gently rolling a fingertip along the lid margin from base toward the eyelid edge — expresses the softened secretions). This twice-daily regimen, maintained consistently over 4-6 weeks, significantly improves meibomian gland function, tear film stability, and dry eye symptoms. The instruction to patients is often described as the '10-minute lid warm': microwave-heated wheat bag, reusable eye mask (EyeBag — medical device, available OTC), or warm flannel, applied to closed eyes for 10 minutes, then gentle expression massage.

The dacryocystorhinostomy (DCR) referral decision for adult nasolacrimal duct obstruction should follow a systematic process — the majority of adults with unilateral chronic watery eye from acquired nasolacrimal duct obstruction (ALDO) will benefit from surgery, which has a success rate of approximately 85-90% (endoscopic endonasal DCR, the preferred technique in most UK centres, bypasses the obstructed nasolacrimal duct entirely by creating a new ostium directly into the nasal cavity). The GP's role: (1) confirm the diagnosis clinically (unilateral overflow watering, no active infection, no conjunctival injection); (2) exclude secondary causes (tumour — refer 2WW if any medial canthal mass or blood-stained discharge); (3) refer to ophthalmology for nasolacrimal syringing to confirm obstruction and DCR assessment. DCR is performed under local or general anaesthesia as a day case. Post-DCR: patients self-irrigate with saline for 4-6 weeks and use topical antibiotic/steroid drops.

The oral doxycycline for posterior blepharitis and meibomian gland dysfunction is one of the most evidence-based antibiotic treatments in ophthalmology that works through a non-antimicrobial mechanism — tetracyclines have anti-inflammatory properties (inhibit matrix metalloproteinases, reduce prostaglandin synthesis, and have a direct effect on meibomian lipid chemistry, reducing the viscosity of meibomian secretions by altering fatty acid composition). Clinical trials consistently demonstrate that doxycycline 100 mg OD for 3 months (or 40 mg modified-release doxycycline — Efracea, licensed for rosacea — also used off-label for blepharitis) significantly improves meibomian gland function, tear film break-up time, and patient-reported dry eye symptoms in posterior blepharitis/MGD. The low-dose anti-inflammatory doxycycline 40 mg modified-release (not the standard antibacterial 100 mg dose) achieves therapeutic tissue concentrations without inducing antibiotic resistance or producing significant antibiotic effects — this is the preferred prescribing approach for long-term blepharitis management.

The olopatadine eye drops (Opatanol 0.1% or Pataday 0.2%) represent the most evidence-based first-line topical treatment for allergic conjunctivitis — olopatadine has a dual mechanism: H1-receptor antihistamine (immediate relief of itch and hyperaemia) combined with mast cell stabilisation (preventing further histamine release on allergen exposure). This dual mechanism makes it significantly more effective than either pure antihistamines (emedastine) or pure mast cell stabilisers (sodium cromoglicate) used alone. Clinical trials consistently show olopatadine 0.1% BD superior to sodium cromoglicate 2% QDS and equivalent to or better than ketotifen 0.025% for symptom relief. The practical advantage: olopatadine 0.1% BD works both acutely (within minutes) and chronically (mast cell stabilisation builds over days) — making it suitable for both episodic and persistent allergic conjunctivitis. Patients should be instructed: apply 1 drop in each affected eye, wait 5 minutes, then apply other eye drops if co-prescribing. Contact lens wearers: remove lenses before drops, wait 15 minutes before reinserting.

The nasolacrimal occlusion technique after instilling eye drops is a simple manoeuvre that can significantly reduce systemic absorption of topical ophthalmic medications — particularly important for topical beta-blockers (timolol 0.5% — systemic absorption can cause bradycardia, bronchospasm, and hypotension, particularly in COPD patients), topical corticosteroids (dexamethasone — systemic absorption can suppress the HPA axis with prolonged use), and topical brimonidine (alpha-2 agonist — CNS depression in children). The technique: after instilling the drop, close the eye and press firmly on the inner corner (punctum) with the fingertip or corner of a tissue for 1-2 minutes. This prevents the drop from entering the nasolacrimal duct, which would carry it to the nasal mucosa and pharynx (where rapid systemic absorption occurs). GPs prescribing topical beta-blockers for glaucoma in patients with COPD or asthma should advise the nasolacrimal occlusion technique — it reduces systemic absorption by approximately 40-60%.

The adenoviral keratitis complication of viral conjunctivitis is an important reason to safety-net patients diagnosed with 'viral conjunctivitis' — adenoviral conjunctivitis (the most common form of infective conjunctivitis in the UK, responsible for approximately 65-70% of all infective conjunctivitis) resolves in approximately 1-2 weeks in most patients. However, in approximately 20-40% of adenoviral conjunctivitis cases, subepithelial infiltrates develop in the cornea at 2-4 weeks after the onset of conjunctivitis. These are immune-mediated opacity deposits under the corneal epithelium that cause glare, blurring of vision, and photophobia. In mild cases they resolve spontaneously over months. In severe cases they require short-term topical corticosteroid treatment (under ophthalmology supervision). The GP safety-netting message for any patient with viral conjunctivitis: 'The discharge and redness should clear in 1-2 weeks. If after 2 weeks you develop any blurring of vision, increasing sensitivity to light, or severe pain — return immediately for same-day assessment.'