Clinical Guides
Conjunctivitis
A clinically focused guide to conjunctivitis across ages, emphasizing diagnostic uncertainty, corneal and contact-lens red flags, neonatal infection, antimicrobial limits, steroid hazards, infection control and Indian access pathways.
MedNext Academy | 13 min read
Conjunctivitis
A clinically focused guide to conjunctivitis across ages, emphasizing diagnostic uncertainty, corneal and contact-lens red flags, neonatal infection, antimicrobial limits, steroid hazards, infection control and Indian access pathways.
Summary
Conjunctivitis is inflammation centred on the conjunctiva, presenting with redness, discharge, irritation, tearing or itch. It is a syndrome, not a single infection. Viral, bacterial and allergic disease are common, but toxic, mechanical, chlamydial, gonococcal, herpetic, immune-mediated and neonatal causes require different decisions. Discharge colour alone does not reliably identify a pathogen. The first clinical task is to decide whether inflammation is confined to the conjunctiva or whether cornea, anterior chamber, sclera, orbit or optic nerve may be involved.
Uncomplicated conjunctivitis usually causes discomfort rather than deep pain and should not materially reduce vision after discharge is cleared. Pain, true photophobia, reduced acuity, corneal opacity or staining, contact-lens wear, trauma, chemical exposure, abnormal pupil, proptosis or impaired ocular movement changes urgency. Hyperacute purulent discharge raises gonococcal disease; chronic follicular disease can indicate chlamydia or a retained foreign body. Any conjunctivitis in the first 28 days of life requires prompt neonatal assessment because gonococcal and herpetic infection can threaten sight and disseminate.
Many acute viral and bacterial episodes are self-limited. Antibiotic drops provide only a modest average improvement in clinical and microbiological resolution for bacterial conjunctivitis and should not be prescribed automatically for every red eye. Allergic disease is managed by allergen reduction, lubricants and selected topical antiallergic therapy. Topical corticosteroids can worsen herpes or microbial keratitis, delay healing, raise intraocular pressure and obscure diagnosis; they require ophthalmic diagnosis and monitoring. Hand hygiene, avoiding shared towels and cosmetics, pausing contact lenses and cleaning contaminated items are central. This draft is educational and remains quarantined following MedNext Clinical Team review.
How Common Is It?
Conjunctivitis is among the most frequent reasons for red-eye consultations, but precise prevalence depends on age, season, setting and definition. Viral outbreaks cluster in households, schools, hostels, clinics and workplaces. Bacterial disease is proportionally more common in children than adults, while allergic conjunctivitis follows sensitisation patterns and may be seasonal or perennial. Clinic data overrepresent persistent, severe and treatment-resistant cases; pharmacy sales overrepresent self-diagnosis and cannot establish disease burden.
Adenovirus causes much contagious acute conjunctivitis and may accompany respiratory symptoms, pharyngitis or preauricular nodes. Acute bacterial conjunctivitis is often self-limited, and clinical appearance does not consistently separate it from viral disease. Allergic conjunctivitis can be common where aeroallergen exposure is high, but severe vernal or atopic keratoconjunctivitis is a distinct, potentially cornea-damaging minority. Chlamydial, gonococcal and herpetic disease are less frequent yet clinically important because they require systemic or specialist management.
India does not have one current national prevalence applicable to every district. Climate, air pollution, crowded living, school outbreaks, access to clean water, contact-lens practices, agricultural exposure and over-the-counter eye drops may affect presentation. Neonatal estimates are especially sensitive to antenatal STI testing, delivery care and prophylaxis practices. A local service should count age, laterality, corneal involvement, laboratory-confirmed outbreak, neonatal disease, contact-lens association, antimicrobial use and referral outcome. Raw “pink eye” attendance cannot show whether clinicians safely excluded keratitis, uveitis or gonococcal disease.
Risk Factors
Viral conjunctivitis spreads through contact with ocular or respiratory secretions, contaminated hands, towels, cosmetics, instruments and surfaces. Household, hostel, school and healthcare outbreaks are therefore plausible. Recent upper-respiratory symptoms or a close contact supports but does not prove a viral cause. Poor hand hygiene and touching both eyes can facilitate sequential bilateral disease. Infection-control failures during tonometry or examination can amplify outbreaks; reusable equipment must follow validated disinfection procedures.
Bacterial risk is influenced by childhood exposure, concurrent blepharitis, nasolacrimal obstruction, ocular surface disease, immunosuppression and contaminated products. Contact-lens wear is a special risk state because a painful red eye may be microbial keratitis, including Pseudomonas infection, rather than simple conjunctivitis. Sleeping, showering or swimming in lenses, topping up solution, poor case hygiene and using tap water increase risk. Gonococcal or chlamydial conjunctivitis follows sexual or perinatal exposure and requires confidential, non-stigmatising history and appropriate testing.
Allergic conjunctivitis occurs with atopy, rhinitis, eczema and allergen exposure; rubbing can worsen inflammation and corneal distortion. Long-term topical medicines, preservatives, cosmetics, occupational chemicals, smoke, dust and traditional remedies can cause toxic or irritant conjunctivitis. Newborn risk includes untreated maternal gonorrhoea or chlamydia, rupture of membranes, genital herpes and gaps in antenatal or delivery care. Risk factors adjust probability, not certainty: a purulent eye can be viral, an itchy eye can coexist with infection, and absence of a reported sexual exposure should not stop evaluation of a hyperacute presentation.
Diagnosis
History
Establish onset, first eye, spread to the other eye, pain, photophobia, change in vision, itch, foreign-body sensation and discharge pattern. Ask about respiratory illness, sick contacts, school or hostel outbreaks, allergy, eczema, trauma, chemical exposure, contact lenses and water exposure. Record every eye drop, including antibiotic-steroid combinations and traditional preparations. In chronic or hyperpurulent disease ask sensitively about sexual exposure and genital symptoms. In a newborn document exact age at onset, delivery, membrane rupture, maternal screening and treatment.
Examination
Measure visual acuity in each eye before drops and recheck after cleaning discharge. Inspect lids, skin, nodes, conjunctival distribution and discharge; evert the upper lid when a foreign body is possible. Assess pupils, ocular movements and pain with movement. Slit-lamp examination should identify follicles, papillae, membranes, haemorrhage, corneal epithelial defect or infiltrate and anterior-chamber inflammation. Fluorescein helps detect corneal disease. A normal-appearing cornea without adequate illumination is not a reliable exclusion. Avoid tonometry if open-globe injury is possible.
Investigations
Most mild acute cases need no laboratory test. Culture or molecular testing is appropriate for hyperacute purulence, suspected gonorrhoea or chlamydia, neonatal disease, severe or recurrent infection, immunocompromise, outbreaks, corneal involvement or failure of appropriate therapy. Gonococcal samples require urgent Gram stain, culture and susceptibility testing, while nucleic-acid testing may support gonorrhoea and chlamydia according to laboratory validation. Corneal scraping belongs to an ophthalmic keratitis pathway. Allergy tests are seldom required for routine seasonal disease. Investigation must not delay immediate irrigation after chemical exposure or urgent systemic treatment of suspected gonococcal neonatal infection.
Differential Diagnosis
Viral conjunctivitis often begins unilaterally with watery discharge, follicles and preauricular nodes before involving the fellow eye. Bacterial disease more often produces mucopurulent discharge and lids stuck on waking, but overlap is substantial. Allergic disease is usually bilateral with prominent itch, chemosis and papillae. Hyperacute copious purulence, rapid reaccumulation and lid oedema suggest gonorrhoea; subacute or chronic follicular conjunctivitis with genital exposure suggests chlamydia. Herpes simplex may be unilateral with vesicles, reduced corneal sensation or dendritic epithelial disease.
The dangerous differential is broader than conjunctivitis. Microbial keratitis produces pain, photophobia, reduced acuity, a corneal epithelial defect or stromal infiltrate and is especially important in contact-lens wearers or after trauma. Anterior uveitis causes consensual photophobia, ciliary injection, cells and flare. Acute angle closure may cause severe pain, headache, nausea, corneal haze and a poorly reactive pupil. Scleritis causes deep pain and tenderness; episcleritis is usually milder. Chemical injury and open-globe trauma are emergencies.
Preseptal cellulitis causes lid inflammation without proptosis or impaired movements; orbital cellulitis adds painful restriction, diplopia, proptosis, reduced vision or systemic toxicity. Dry eye, blepharitis, retained subtarsal foreign body, nasolacrimal obstruction, medicamentosa and contact dermatitis commonly mimic or sustain symptoms. Chronic unilateral disease raises molluscum, canaliculitis, a retained foreign body, nasolacrimal tumour or conjunctival neoplasia. In neonates distinguish chemical irritation, nasolacrimal obstruction and bacterial, chlamydial, gonococcal or herpetic infection, but do not use timing alone to exclude a dangerous organism.
Management
Start by protecting vision and stopping the exposure. Chemical injury requires immediate copious irrigation. Contact lenses are removed, retained with the case if microbiological advice requests them, and not resumed until symptoms have resolved and an eye professional confirms safety. Suspected keratitis, uveitis, gonococcal disease, herpes, orbital disease or neonatal infection follows an urgent specialist pathway. Mild viral conjunctivitis is managed with cool compresses, preservative-free lubricants and hygiene; antibiotics do not treat adenovirus.
For uncomplicated suspected bacterial conjunctivitis, explain diagnostic uncertainty and spontaneous recovery. Delayed treatment or observation can be reasonable when follow-up and safety-netting are reliable. A 2023 Cochrane review found that topical antibiotics modestly improved the chance and speed of clinical and microbiological resolution, but most placebo recipients also resolved. Antibiotics do not justify skipping acuity or corneal examination. Hyperacute gonococcal disease needs systemic therapy and urgent ophthalmic and sexual-health care; topical drops alone are inadequate. Adult chlamydial disease also requires systemic treatment and partner management.
Allergic conjunctivitis responds to allergen avoidance, cold compresses, lubricants and selected topical dual-acting antihistamine or mast-cell stabilising therapy. Severe vernal or atopic disease needs ophthalmology because corneal involvement may scar. Avoid chronic vasoconstrictor “whitening” drops. Do not prescribe topical anaesthetic for home use. Corticosteroid or immunomodulatory drops require ophthalmic assessment. Review a patient whose symptoms worsen, vision changes, pain or photophobia develops, discharge remains hyperpurulent, or the course is prolonged or recurrent.
Prescribing Information
No antibiotic is automatically indicated for a red eye. When uncomplicated bacterial conjunctivitis is sufficiently likely and treatment is chosen, use a locally approved topical agent, correct formulation, laterality, frequency and duration after checking allergy, age, pregnancy, contact-lens status and corneal findings. Avoid repeatedly changing antibiotics solely because discharge persists for a day. Obtain culture in severe, recurrent, neonatal, hyperacute or treatment-resistant disease. Stewardship is especially important because many cases are viral or self-limited and the average antibiotic benefit is modest.
Suspected gonococcal conjunctivitis is a systemic infection emergency. It needs urgent parenteral treatment according to the current national or specialist STI protocol, ocular lavage and evaluation for corneal and disseminated disease; coinfection and partners require assessment. Chlamydial conjunctivitis needs systemic therapy and partner management because topical therapy alone does not eradicate genital or nasopharyngeal infection. Neonatal dosing is weight- and age-dependent and must be led by paediatrics, ophthalmology and microbiology. Infant macrolides have specific adverse-effect considerations, so an adult prescription must never be copied.
Topical corticosteroids can worsen herpes simplex epithelial keratitis, fungal or bacterial keratitis, delay epithelial healing, raise intraocular pressure and promote cataract. Combination antibiotic-steroid drops sold without adequate examination are particularly hazardous. Steroids should be initiated only after an ophthalmic diagnosis with planned pressure and corneal monitoring. Antihistamine or mast-cell stabiliser drops can help allergic disease; oral sedating antihistamines may worsen dryness. Avoid home topical anaesthetics and unsterile traditional preparations. Teach one drop at a time, hand hygiene, no bottle-tip contact and separation of multiple drops.
When to Refer
Arrange same-day ophthalmic assessment for pain, photophobia, reduced vision, corneal opacity or epithelial defect, abnormal pupil, contact-lens-associated red eye, suspected herpes, trauma, chemical injury after irrigation, hyperacute purulent discharge, severe immunosuppression or failure that suggests keratitis. Contact-lens wear should lower the threshold even when the patient calls symptoms “conjunctivitis”. Do not allow an empiric antibiotic prescription to delay slit-lamp examination.
Refer urgently to emergency or combined ophthalmic and infectious-disease care for suspected gonococcal conjunctivitis. Conjunctivitis in a neonate aged 28 days or younger needs prompt paediatric assessment, conjunctival sampling and consideration of maternal and infant gonorrhoea, chlamydia and herpes. Fever, poor feeding, respiratory symptoms, vesicles or systemic illness increases urgency. Chronic follicular disease, recurrent unilateral symptoms, conjunctival scarring, membrane formation, severe vernal disease or suspected mucous-membrane pemphigoid requires specialist diagnosis.
Routine mild viral or allergic disease can be managed in primary care when acuity is normal and red flags are absent. Review rather than refer automatically if improvement follows an appropriate conservative plan, but give a time-linked safety net. In India, referral may be through a district hospital, medical college, government eye unit, paediatric service or accredited private provider. State whether emergency slit lamp, microbiology and neonatal care are available. Confirm cost, transport, opening hours and a named receiving service rather than giving a generic instruction to “see an eye doctor”.
Red Flags
Pain rather than grittiness, true photophobia, reduced visual acuity, corneal haze, focal white infiltrate, fluorescein uptake over an opacity, anterior-chamber reaction or a relative afferent pupillary defect is not routine conjunctivitis. A contact-lens wearer with any of these findings has microbial keratitis until urgently assessed. A fixed mid-dilated pupil, severe headache, nausea and cloudy cornea suggests acute angle closure. Immediate irrigation takes priority in chemical injury; suspected open globe is shielded without pressure and referred emergently.
Copious purulent discharge that rapidly reaccumulates, severe lid oedema or corneal involvement can indicate gonococcal infection and threaten perforation. Neonatal redness or discharge is a red flag even if the infant appears well. Gonococcal disease can progress quickly and disseminate; chlamydial disease may coexist with nasopharyngeal infection or pneumonia; herpes can involve the cornea and central nervous system. Obtain specialist care rather than prescribing topical drops remotely.
Proptosis, painful or restricted ocular movement, diplopia, colour desaturation, reduced vision, severe headache, fever or toxicity suggests orbital rather than conjunctival disease. Vesicles on the eyelid or forehead, decreased corneal sensation or a dendritic lesion raises herpes. Membranes, symblepharon, conjunctival scarring, persistent unilateral inflammation, a lid lesion or focal bleeding can indicate cicatrizing or neoplastic disease. Worsening after a steroid-containing drop is itself a warning. Return precautions should be written and understandable, because diagnostic features can evolve after the initial visit.
Indian Clinical Context
India's eye-care pathways range from community and primary services to district eye units, medical colleges and specialist corneal centres. Crowding, school or hostel outbreaks and long travel distances can make infection-control advice and follow-up difficult. Explain practical measures: wash hands with soap and water, avoid touching the eyes, do not share towels, pillows, cosmetics or drops, clean frequently touched surfaces and stay away from swimming while discharge is active. Exclusion from school or work should follow current institutional or public-health policy rather than an arbitrary antibiotic rule.
Over-the-counter access to antibiotic, vasoconstrictor and steroid-combination drops creates a distinctive safety risk. Ask to see every bottle. A patient may not know that a “redness” drop contains a corticosteroid. Unregulated traditional preparations, saliva, breast milk or plant extracts can contaminate or injure the cornea and should not be placed in the eye. Stewardship must coexist with access: observation is safe only when the patient can return promptly if pain, photophobia or visual loss develops.
The National Health Mission child-eye screening guidance recognises ophthalmia neonatorum during the first four weeks and differentiates chemical, bacterial and viral causes, but local neonatal protocols and antimicrobial resistance must govern treatment. Maternal STI evaluation should be confidential and non-stigmatising. Contact-lens users need counselling against tap water, swimming and sleeping in lenses and require access to urgent corneal review. Public messaging should not claim that every red eye is contagious or needs antibiotics; it should teach red flags, hygiene and where emergency examination is available.
NMC Competency Mapping
NMC ophthalmology competency OP3.1 requires history taking in a patient with red eye and enumeration of causes. OP3.3 requires description of the aetiology, pathophysiology, ocular features, differential diagnosis, complications and management of conjunctivitis. OP3.4 and OP3.5 separately address trachoma and vernal catarrh, while OP3.9 covers correct instillation of eye drops in a simulated environment. This guide supports those outcomes without collapsing all conjunctival inflammation into acute infection.
A competent learner should measure acuity, identify the dominant symptom, classify discharge without overinterpreting it, examine lids and pupils, evert the lid when appropriate and inspect the cornea with fluorescein under supervision. The clinical presentation should state why keratitis, uveitis, angle closure, scleritis, cellulitis, trauma and chemical injury are less or more likely. Learners should distinguish viral, bacterial and allergic patterns while acknowledging their overlap, and recognise hyperacute gonococcal, chronic chlamydial and neonatal pathways.
Management learning includes infection control, antimicrobial stewardship, contact-lens cessation, safe drop technique and explicit follow-up. Reading does not certify slit-lamp examination, corneal scraping, membrane removal or steroid prescribing. The learner should explain why topical antibiotics offer only modest benefit in typical bacterial disease, why systemic treatment is needed for gonococcal or chlamydial infection, and why an unsupervised steroid combination can blind. Communication should be non-stigmatising for STI-related disease and practical for families navigating variable Indian eye services.
Key Exam Pearls for NEET PG
Viral conjunctivitis classically gives watery discharge, follicles and preauricular nodes; bacterial disease gives mucopurulent discharge; allergic disease produces prominent bilateral itch, chemosis and papillae. These are probability clues, not perfectly specific tests. A follicle is a lymphoid response without a central vessel; a papilla has a central vascular core. Membranes, corneal involvement and reduced vision increase severity. Adenovirus is highly transmissible, and antibiotics do not treat it.
Pain, photophobia and reduced acuity should move the answer away from uncomplicated conjunctivitis toward keratitis, uveitis, scleritis, angle closure or trauma. In a contact-lens wearer, urgently exclude microbial keratitis. Hyperacute copious purulence suggests gonococcus and needs systemic treatment and corneal assessment. Chronic follicular conjunctivitis with genital exposure suggests chlamydia and also needs systemic therapy and partner management. Ophthalmia neonatorum occurs in the first 28 days; gonococcal disease tends to be early and aggressive, while chlamydial disease often presents later, but timing alone cannot safely exclude either.
Most uncomplicated bacterial conjunctivitis resolves spontaneously; topical antibiotics modestly speed resolution. Steroid drops are not a routine answer: they may worsen herpes or microbial keratitis and raise intraocular pressure. Allergic disease is treated with avoidance, cold compresses, lubricants and topical antihistamine or mast-cell stabilisation, with ophthalmology for corneal or severe vernal disease. Always state hygiene, no shared towels or cosmetics, no contact lenses during active disease and urgent return for pain, photophobia or visual change.
Frequently Asked Questions
Does yellow or green discharge prove that conjunctivitis is bacterial?
No. Mucopurulent discharge increases the probability of bacterial disease, but viral infection and other ocular-surface disorders can overlap. Diagnosis also uses pain, itch, visual acuity, corneal examination, contact-lens status, exposure history and the tempo of illness. Severe or rapidly reaccumulating pus needs urgent gonococcal assessment.
Does every case of bacterial conjunctivitis need antibiotic eye drops immediately?
No. Many uncomplicated cases resolve without treatment, and trials show only a modest average benefit from topical antibiotics. Observation or delayed treatment can be reasonable when acuity is normal, the cornea is clear and follow-up is reliable. Neonatal, gonococcal, chlamydial, contact-lens or corneal disease follows a different pathway.
Why are steroid combination drops dangerous in an undiagnosed red eye?
Topical corticosteroids can worsen herpes simplex, fungal or bacterial keratitis, delay epithelial healing, raise intraocular pressure and hide progression. A combined antibiotic does not neutralise those risks. Steroid treatment requires an ophthalmic diagnosis and monitoring of the cornea and pressure; worsening on such a drop requires urgent reassessment.
When should a person with conjunctivitis stop wearing contact lenses?
Remove lenses immediately when redness, discharge, pain or visual change begins and do not resume until symptoms have resolved and an eye professional confirms it is safe. Pain, photophobia, reduced acuity or a corneal spot in a lens wearer needs same-day assessment for microbial keratitis, not remote treatment as simple conjunctivitis.
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