Special Senses & Otolaryngology

Conjunctivitis: bacterial, viral, allergic

Clinical Overview and When to Suspect Conjunctivitis

— Viral (most common overall in adults) — usually adenovirus

— Bacterial (most common in children) — S. pneumoniae, H. influenzae, S. aureus, Moraxella

— Allergic — bilateral, itch-dominant, atopic background

— Decreased visual acuity

— Severe pain, photophobia, or ciliary flush (limbal injection)

— Fixed/irregular pupil, corneal opacity, hypopyon

— Contact lens wearer with red eye (think Pseudomonas keratitis)

— Recent ocular surgery or trauma

— Severe headache, nausea (acute angle-closure glaucoma)

— Conjunctivitis drives ~1% of all primary care visits in the US

— Antibiotic overprescribing is a quality measure — >60% of viral cases receive unnecessary topical antibiotics

— School/daycare exclusion policies vary; CDC does not mandate exclusion for most viral or allergic cases

Conjunctivitis = inflammation of the bulbar/palpebral conjunctiva, the most common cause of "red eye" in primary care and urgent care.

Three dominant outpatient etiologies tested on Step 3:

Suspect conjunctivitis when a patient presents with red eye + discharge or itching + preserved visual acuity + no photophobia.

Red flags that argue AGAINST simple conjunctivitis and require same-day ophthalmology referral:

Epidemiologic context for the family medicine setting:

Board pearl: On Step 3, the vignette discriminates the three types using discharge character (purulent vs watery vs stringy mucoid), laterality, itching, and preauricular adenopathy — memorize these four discriminators before anything else.

Step 3 management: Most conjunctivitis is a clinical diagnosis without cultures or labs. Reserve cultures for hyperacute, neonatal, contact-lens–associated, treatment-refractory, or immunocompromised presentations. Visual-acuity testing should be performed in every red eye to triage out keratitis and uveitis before assigning the conjunctivitis label and discharging from clinic.

Presentation Patterns and Key History

— Watery/serous discharge, gritty or "sandy" foreign-body sensation

— Starts unilateral, becomes bilateral within 1–2 days

— Often preceded or accompanied by URI symptoms, sore throat, fever

— Recent sick contact, daycare, or healthcare exposure

— Epidemic keratoconjunctivitis (EKC) and pharyngoconjunctival fever are adenoviral subtypes

— Thick, purulent, yellow-green discharge that re-accumulates within minutes of wiping

— Eyelids "glued shut" upon waking

— Typically unilateral at onset, may become bilateral

— Less itching, minimal systemic symptoms

— Hyperacute (<24 h) copious purulent discharge → gonococcal until proven otherwise; chlamydial is more indolent with chronic mucopurulent discharge and follicles

— Bilateral from onset, intense itching is the defining feature

— Stringy/ropy mucoid discharge, watery tearing

— Seasonal pattern, exposure to pollen/pets/dust

— History of atopy: eczema, allergic rhinitis, asthma

— Often accompanied by sneezing, nasal congestion, eyelid edema

— Onset, laterality, discharge character, itch vs pain vs gritty

— Contact lens use and hygiene (overnight wear, tap-water rinsing)

— Trauma, chemical exposure, recent eye surgery

— Sexually transmitted infection risk (gonococcal/chlamydial)

— Recent antibiotic use, prior episodes, immunization status

Viral conjunctivitis (adenoviral):

Bacterial conjunctivitis:

Allergic conjunctivitis:

Key history elements to elicit on every red-eye visit:

Key distinction: Itching = allergic; burning/grittiness = viral; mattering shut = bacterial. If a stem mentions all three, the dominant symptom wins.

Board pearl: A patient with conjunctivitis plus preauricular lymphadenopathy is viral (adenoviral) until proven otherwise — bacterial conjunctivitis virtually never causes preauricular nodes, with the lone exception of gonococcal.

Physical Exam Findings and Ocular Assessment

— Visual acuity (Snellen) — must be preserved in conjunctivitis

— Pupillary size, shape, reactivity — should be normal

— External lids and lashes

— Conjunctival injection pattern (diffuse vs ciliary flush)

— Cornea clarity (fluorescein staining if any pain or contact lens use)

— Anterior chamber depth and clarity (no hypopyon)

— Preauricular and submandibular lymph nodes

— Diffuse bulbar injection, watery discharge

— Follicular reaction of tarsal conjunctiva (small lymphoid bumps)

— Tender preauricular lymphadenopathy (hallmark)

— Possible subepithelial corneal infiltrates in EKC (decreased acuity → refer)

— Mucopurulent discharge welling at lid margins

— Papillary reaction (flat-topped vascularized bumps) of tarsal conjunctiva

— No preauricular nodes (except gonococcal/chlamydial)

— Chemosis variable

— Bilateral conjunctival edema (chemosis — glassy appearance)

— Cobblestone papillae on superior tarsal conjunctiva (vernal/atopic)

— Periorbital allergic "shiners," Dennie-Morgan lines

— Eyelid swelling, no lymphadenopathy

Always document a structured red-eye exam before labeling as conjunctivitis:

Viral findings:

Bacterial findings:

Allergic findings:

Vital signs and systemic exam: generally normal; fever suggests viral URI overlap or, rarely, periorbital/orbital cellulitis if eyelid signs are out of proportion.

Key distinction: Ciliary flush (perilimbal redness) signals keratitis, uveitis, or angle-closure — NOT conjunctivitis. If you see it, stop, do not label as conjunctivitis, and refer urgently.

Board pearl: Fluorescein exam revealing a dendritic ulcer = HSV keratitis — do NOT use topical steroids and refer same day. A red eye with photophobia and decreased vision is a corneal or intraocular problem until proven otherwise; conjunctivitis essentially never reduces visual acuity beyond mild blur cleared by blinking.

Diagnostic Workup — Initial Evaluation

— AdenoPlus / RPS Adeno Detector rapid antigen test for adenovirus (sens ~85–90%, spec >95%); useful to curb antibiotic overuse and confirm contagious viral disease, but rarely changes management in primary care

— Conjunctival swab for Gram stain and bacterial culture if hyperacute, neonatal, contact-lens user, immunocompromised, or treatment failure

— NAAT for N. gonorrhoeae and C. trachomatis if STI risk, hyperacute purulent discharge, or inclusion conjunctivitis pattern

— Giemsa stain of conjunctival scrapings — intracytoplasmic inclusion bodies suggest chlamydial inclusion conjunctivitis

— Gram stain, culture, and NAAT for GC/CT

— Day 0–1: chemical (silver nitrate, now rare)

— Day 2–5: gonococcal (IV/IM ceftriaxone, admission)

— Day 5–14: chlamydial (PO erythromycin × 14 days; topical alone insufficient and risks pyloric stenosis association still warrants oral)

— Any timing: HSV — consider IV acyclovir, ophthalmology

Conjunctivitis is a clinical diagnosis in the vast majority of cases — routine labs, cultures, and imaging are NOT indicated for typical viral, bacterial, or allergic presentations.

Point-of-care testing options (selective use):

Fluorescein staining is mandatory whenever there is pain, photophobia, contact lens use, or any visual change — to exclude corneal ulcer, abrasion, or HSV dendrite.

Allergy workup is generally not needed acutely; in chronic/recurrent allergic conjunctivitis, consider specific IgE testing or skin-prick testing through allergy referral to guide environmental control.

Neonates (<30 days) with conjunctivitis — ophthalmia neonatorum — always warrant workup:

Step 3 management: Do not order routine cultures, CBC, or imaging for the typical adult with mild–moderate conjunctivitis — the highest-yield diagnostic action is a focused slit-lamp/penlight exam with visual acuity and fluorescein. Reserve labs for the four red-flag scenarios: hyperacute, neonatal, contact lens, or refractory.

Diagnostic Workup — Advanced or Confirmatory Studies

— Diagnosis uncertain after primary care evaluation

— Decreased visual acuity, photophobia, severe pain

— Suspected keratitis, uveitis, episcleritis, or scleritis

— Persistent symptoms beyond 7–10 days of appropriate therapy

— Contact-lens–associated red eye (rule out microbial keratitis)

— Blood agar, chocolate agar (for Neisseria and Haemophilus), and Thayer-Martin if GC suspected

— Viral cultures rarely useful clinically; PCR available for adenovirus and HSV

— Gold standard for C. trachomatis and N. gonorrhoeae conjunctival infection

— Sensitivity >95%, allows simultaneous urogenital testing — also test partners and screen for other STIs (HIV, syphilis)

— PCR of corneal/conjunctival scrapings if dendrites or vesicular lid lesions

— Tzanck smear of historical interest only; PCR has replaced it

— Eosinophils → allergic

— Neutrophils predominant → bacterial

— Mononuclear/lymphocytic → viral

— Multinucleated giant cells → HSV

— Intracytoplasmic inclusions → chlamydial

— Refer to allergy/immunology for skin-prick or serum specific IgE

— Consider vernal vs atopic keratoconjunctivitis evaluation by ophthalmology — these can scar cornea

Slit-lamp biomicroscopy (often via ophthalmology referral) when:

Conjunctival cultures and sensitivities:

NAAT testing:

HSV/VZV testing:

Conjunctival scraping with Giemsa or Wright stain:

Imaging: CT orbits with contrast only if orbital cellulitis is suspected (proptosis, ophthalmoplegia, pain with eye movement, vision loss) — not for conjunctivitis itself.

Allergic workup, when chronic/severe:

Board pearl: Decreased vision + red eye = NOT routine conjunctivitis. The single highest-yield next step on a Step 3 stem with photophobia, decreased acuity, or contact-lens wear is same-day ophthalmology referral with slit-lamp exam — not empiric antibiotics.

Management Logic — Choosing Among the Three Pathways

— Viral → supportive, hygiene, time

— Bacterial → topical antibiotics (or systemic for GC/CT)

— Allergic → allergen avoidance + topical antihistamine/mast cell stabilizer

— Cold compresses, artificial tears, antihistamine drops for symptomatic itch

— Strict hand hygiene; do NOT share towels/pillows

— Discontinue contact lenses until resolution

— Self-limited over 7–14 days, may take up to 3 weeks

— Antibiotics provide NO benefit and increase resistance

— Topical steroids only by ophthalmology for symptomatic subepithelial infiltrates

— Mild cases in immunocompetent adults often self-resolve in 1–2 weeks

— Topical antibiotics shorten duration and reduce transmission — start empirically for moderate–severe cases, contact lens wearers, healthcare workers, and children in daycare

— Reassess at 48–72 hours if no improvement

— Identify and avoid trigger

— Cold compresses, preservative-free artificial tears (dilutional washout)

— First-line: dual-action topical antihistamine/mast-cell stabilizer (olopatadine, ketotifen, bepotastine)

— Add oral antihistamine if systemic allergic symptoms

— Refer to allergy for chronic/severe disease; ophthalmology if vision-threatening vernal/atopic forms

Anchor management on the etiologic triage:

Viral conjunctivitis pathway:

Bacterial conjunctivitis pathway:

Allergic conjunctivitis pathway:

CCS pearl: When the CCS case opens with a red eye, your first orders are visual acuity, penlight + fluorescein exam, and history of contact lens use before any drug. Skipping acuity is a common point-loss step; "ophthalmology consult" advances the clock when the stem includes pain, photophobia, or decreased vision.

Step 3 management: Avoid topical corticosteroids in primary care — they can worsen HSV keratitis, prolong adenoviral shedding, and raise IOP. Steroids belong to ophthalmologists, not family physicians, for red-eye disease.

Pharmacotherapy — First-Line Regimens

— Erythromycin 0.5% ophthalmic ointment, ½-inch ribbon QID × 5–7 days (cheap, broad, safe in pregnancy/peds)

— Polymyxin B–trimethoprim drops, 1 drop q3–6h × 5–7 days

— Azithromycin 1% drops BID × 2 days, then daily × 5 days

— Sulfacetamide 10% — older, more irritation, declining use

— Fluoroquinolone drops: moxifloxacin 0.5%, gatifloxacin 0.3–0.5%, or ciprofloxacin 0.3%, 1 drop q2–4h while awake × 5–7 days

— Discontinue contacts until symptom-free × 24 h after antibiotic completion

— Replace lens case and discard current pair

— Ceftriaxone 1 g IM × 1 (adult) — systemic therapy required

— Plus saline lavage of conjunctiva

— Plus empiric doxycycline 100 mg BID × 7 days for chlamydial co-infection

— Admit if corneal involvement; ophthalmology consult

— Azithromycin 1 g PO × 1 or doxycycline 100 mg BID × 7 days

— Treat sexual partners; report per state STI requirements

— No antiviral indicated for adenovirus

— HSV keratoconjunctivitis → trifluridine 1% drops or oral acyclovir 400 mg 5×/day; refer to ophthalmology

— Olopatadine 0.2% or 0.7% daily, or ketotifen 0.025% BID (OTC)

— Add oral cetirizine/loratadine for systemic atopy

— Avoid chronic vasoconstrictor drops (naphazoline) — rebound hyperemia

Bacterial conjunctivitis — uncomplicated, non–contact-lens wearer:

Bacterial conjunctivitis — contact lens wearer (cover Pseudomonas):

Gonococcal conjunctivitis (hyperacute):

Chlamydial (inclusion) conjunctivitis:

Viral conjunctivitis:

Allergic conjunctivitis:

Board pearl: Topical aminoglycosides (gentamicin, tobramycin) are toxic to corneal epithelium with prolonged use; reserve for Pseudomonas keratitis under ophthalmology. For routine bacterial conjunctivitis, choose erythromycin ointment or polymyxin-trimethoprim — they are first-line for cost and safety.

Expanded Pharmacology and Adjunctive Therapy

— Olopatadine, ketotifen, bepotastine, alcaftadine, epinastine

— Onset within minutes (H1 block) plus sustained mast cell stabilization

— Once- or twice-daily dosing improves adherence

— Safe in pregnancy (category B/limited data — olopatadine commonly used)

— Require 2-week loading before full benefit; useful for seasonal prophylaxis started before allergy season

— Reduce itching/inflammation; second-line allergic adjunct

— Avoid in contact lens wearers; can cause corneal melts in dry eye

— Ophthalmology-prescribed only

— Indications: severe allergic (vernal, atopic), EKC subepithelial infiltrates, post-op

— Risks: cataract, glaucoma (IOP rise), HSV reactivation, fungal/bacterial superinfection

— Chronic allergic and dry-eye overlap; specialist-managed

— Preservative-free artificial tears multiple times daily (dilutes allergens, soothes inflammation)

— Cold compresses 4–6× daily

— Avoid eye rubbing (worsens mast cell degranulation and can cause keratoconus over years)

— Lid hygiene with warm compresses for concurrent blepharitis

— Topical vasoconstrictors >3 days → rebound conjunctivitis medicamentosa

— Topical anesthetics for symptomatic relief → corneal toxicity, neurotrophic ulcer (never prescribe for home use)

— Aminoglycosides chronically → epithelial toxicity

— Neomycin → high contact-allergy rates

Topical antihistamine/mast-cell stabilizers (allergic — preferred):

Pure mast-cell stabilizers (cromolyn, lodoxamide, nedocromil):

Topical NSAIDs (ketorolac 0.5%):

Topical corticosteroids (loteprednol, fluorometholone, prednisolone):

Immunomodulators (cyclosporine 0.05%, lifitegrast):

Adjunctive measures across all types:

Drugs to AVOID or use cautiously:

Step 3 management: When a patient with "allergic conjunctivitis" returns worse after using OTC tetrahydrozoline/naphazoline for 2 weeks, the diagnosis is conjunctivitis medicamentosa — stop the offending drop, switch to preservative-free tears plus olopatadine, and counsel that vasoconstrictor drops should never be used more than 72 hours.

Special Populations — Elderly and Renal/Hepatic Impairment

— Coexisting dry eye disease mimics and worsens allergic/viral conjunctivitis — always evaluate tear film

— Blepharitis and meibomian gland dysfunction are extremely common >60 y/o and present as chronic bilateral red, gritty eyes; treat with lid hygiene, warm compresses, omega-3s, not antibiotic drops

— Anticholinergic burden (antihistamines, TCAs, urinary antispasmodics) worsens dry eye and mimics allergic conjunctivitis

— Reduced manual dexterity and visual impairment affect drop self-administration — assess technique, consider caregiver instillation or punctal occlusion training

— Higher risk of pseudomonal/MRSA flora in nursing home residents — lower threshold for culture in refractory cases

— Avoid first-generation (diphenhydramine, hydroxyzine, chlorpheniramine) per Beers criteria — confusion, falls, urinary retention, anticholinergic load

— Use second-generation: loratadine, cetirizine, fexofenadine — fexofenadine is least sedating

— Oral doxycycline preferred over azithromycin/erythromycin for chlamydial conjunctivitis in CKD (no renal dose adjustment for doxycycline)

— Cetirizine — reduce dose to 5 mg daily if CrCl <30

— Fexofenadine — reduce to 60 mg daily if CrCl <80

— Acyclovir for HSV — adjust per CrCl; risk of crystal nephropathy with high doses

— Erythromycin and azithromycin metabolized hepatically — monitor in advanced cirrhosis

— Doxycycline preferred when hepatic dysfunction is mild–moderate

Topical ophthalmic therapy minimizes systemic exposure, so renal and hepatic dose adjustments are rarely required for conjunctivitis drops. However, several nuances matter for the older adult:

Elderly considerations:

Oral antihistamines in elderly:

Renal impairment:

Hepatic impairment:

Board pearl: A nursing home resident with chronic bilateral red, crusted lid margins and gritty eyes is almost always blepharitis with secondary dry eye, NOT bacterial conjunctivitis. Treatment is warm compresses, lid scrubs, and artificial tears — antibiotic drops alone will not resolve the underlying meibomian gland disease and may select resistant organisms.

Special Populations — Pregnancy, Pediatrics, Neonatal

— Erythromycin ophthalmic ointment — preferred topical antibiotic (category B, minimal systemic absorption)

— Polymyxin B-trimethoprim — acceptable

— Avoid fluoroquinolones when feasible (limited safety data, theoretical cartilage concerns — though topical exposure is minimal)

— Avoid tetracyclines/doxycycline in pregnancy and lactation (tooth staining, bone deposition)

— Chlamydial conjunctivitis in pregnancy: azithromycin 1 g PO × 1

— Gonococcal: ceftriaxone 500 mg–1 g IM × 1 — safe in pregnancy

— Topical antihistamines: olopatadine and ketotifen considered low risk

— Oral antihistamines: loratadine and cetirizine preferred

— Most common bacterial pathogens: nontypeable H. influenzae, S. pneumoniae, Moraxella

— Conjunctivitis–otitis syndrome: bilateral purulent conjunctivitis + ipsilateral otitis media → H. influenzae; treat with oral amoxicillin–clavulanate (systemic therapy needed; topicals insufficient)

— Daycare: AAP allows return when treatment started and discharge improving; many states require 24 h of antibiotics

— Adenoviral: no school exclusion universally required, but contagious — emphasize hand hygiene

— <24 h: chemical (silver nitrate prophylaxis — now rare in US, replaced by erythromycin ointment)

— 2–5 days: gonococcal — admit, IV/IM ceftriaxone 25–50 mg/kg (single dose), saline lavage; can cause corneal perforation

— 5–14 days: chlamydial — oral erythromycin 50 mg/kg/day × 14 days (topical alone insufficient; oral therapy because of associated pneumonitis risk). Counsel on infantile hypertrophic pyloric stenosis association with erythromycin in infants <6 weeks — informed discussion required

— Any time: HSV — IV acyclovir, ophthalmology

— Universal US prophylaxis: erythromycin 0.5% ophthalmic ointment to all newborns within 1 h of birth (mandated in most states)

Pregnancy:

Pediatric conjunctivitis:

Neonatal conjunctivitis (ophthalmia neonatorum) — always concerning, always work up:

Step 3 management: Newborn with purulent conjunctivitis on day 3 of life → ceftriaxone IM + admit + ophthalmology + test mother and partners for STIs + report per state law. Never send these patients home on topical antibiotics alone.

Complications and Adverse Outcomes

— Subepithelial corneal infiltrates in EKC — cause persistent blurred vision and glare for weeks to months; managed with topical steroids by ophthalmology

— Symblepharon and conjunctival scarring in severe cases

— Pseudomembrane/true membrane formation (fibrinous exudate) — may require peel by ophthalmology

— Prolonged viral shedding (up to 14 days); high transmission in clinics and hospitals

— Gonococcal: corneal ulceration and perforation within 24–48 h — sight-threatening emergency

— Chlamydial trachoma (serovars A–C) — leading infectious cause of blindness worldwide; chronic follicular conjunctivitis → entropion, trichiasis, corneal scarring

— Preseptal/orbital cellulitis from contiguous spread

— Endophthalmitis (rare without trauma or surgery)

— Vernal and atopic keratoconjunctivitis can produce shield ulcers, corneal scarring, keratoconus

— Chronic eye rubbing → keratoconus

— Steroid-dependence with cataract and glaucoma

— Fluoroquinolone drops: precipitate formation (ciprofloxacin), corneal toxicity

— Aminoglycoside epithelial toxicity

— Topical vasoconstrictor rebound (conjunctivitis medicamentosa)

— Topical anesthetic abuse → corneal melt

— Steroid: IOP rise, posterior subcapsular cataract, HSV reactivation

— Misdiagnosing HSV keratitis as bacterial conjunctivitis and prescribing steroids → dendritic ulcer progression, permanent corneal scarring

— Missing acute angle-closure glaucoma → permanent vision loss within hours

— Missing contact lens microbial keratitis → corneal ulcer, perforation, enucleation

Viral (adenoviral) complications:

Bacterial complications:

Allergic complications:

Treatment-related adverse events:

Missed-diagnosis morbidity:

Board pearl: Hyperacute (<24 h) copious purulent conjunctivitis in a sexually active adult = gonococcal until proven otherwise and a true ocular emergency because of the bacterium's ability to penetrate intact corneal epithelium and perforate within 48 hours. Same-day IM ceftriaxone and ophthalmology consult are mandatory.

When to Escalate — Referral, Inpatient, or Emergent Care

— Decreased visual acuity beyond mild blur

— Moderate–severe eye pain or photophobia

— Ciliary flush (perilimbal injection)

— Corneal opacity, infiltrate, ulcer, or dendrite on fluorescein

— Hypopyon or hyphema

— Fixed or irregular pupil

— Suspected angle-closure glaucoma (mid-dilated pupil, firm globe, headache, nausea)

— Contact lens wearer with red eye + pain/discharge — assume microbial keratitis

— Hyperacute purulent discharge (gonococcal)

— Penetrating ocular injury or chemical exposure (immediate irrigation FIRST)

— Post-operative red eye within 6 weeks of intraocular surgery

— No improvement after 48–72 h of appropriate empiric therapy

— Suspected gonococcal keratoconjunctivitis with corneal involvement → admit for IV ceftriaxone, hourly saline lavage, ophthalmology at bedside

— Neonatal conjunctivitis → admit for workup and IV/IM antibiotics

— Orbital cellulitis (proptosis, pain with EOM, ophthalmoplegia, fever) → CT orbits, IV broad-spectrum antibiotics, ENT/ophthalmology

— Chemical burns → continuous irrigation until pH neutral, then transfer

— Allergy/immunology: recurrent or year-round allergic conjunctivitis for desensitization

— Infectious disease/public health: gonococcal/chlamydial cases (partner notification, STI workup)

— Pediatrics: persistent neonatal tearing — consider nasolacrimal duct obstruction (massage, refer at 12 months)

Same-day ophthalmology referral indications:

Emergency department / inpatient triage:

Subspecialty referral patterns:

CCS pearl: On a CCS case with red eye + photophobia + decreased visual acuity, the highest-yield early orders are: visual acuity check, fluorescein staining, slit-lamp exam (or "ophthalmology consult, urgent"), and IOP measurement. Empiric antibiotic drops without first ruling out keratitis, uveitis, or angle-closure will lose points and may worsen outcomes. Document hand-off and ensure ophthalmology has seen the patient before closing the case.

Key Differentials — Other Causes of Conjunctival Injection

— Adenoviral conjunctivitis — watery, follicular, preauricular nodes

— Bacterial conjunctivitis — purulent, papillary, no nodes

— Gonococcal — hyperacute, copious purulence, lid edema, preauricular nodes

— Chlamydial (adult inclusion) — chronic mucopurulent, follicular, sexually active adult

— Trachoma — chronic follicular, endemic regions, leads to scarring/entropion

— HSV conjunctivitis — unilateral, vesicular lid lesions, dendrites on cornea

— VZV (zoster ophthalmicus) — V1 dermatome rash, Hutchinson's sign (nasal tip), refer

— Allergic — bilateral itching, atopic background, papillary reaction

— Vernal keratoconjunctivitis — young males, warm climates, giant cobblestone papillae, shield ulcers

— Atopic keratoconjunctivitis — adult atopics, chronic, can scar

— Giant papillary conjunctivitis — contact lens or ocular prosthesis-related; treat by removing offending object

— Conjunctivitis medicamentosa — chronic vasoconstrictor or preservative (benzalkonium) drop use

— Toxic/chemical conjunctivitis — occupational exposures, cosmetics

— Dry eye disease (keratoconjunctivitis sicca) — common in elderly, Sjögren's

— Pterygium/pinguecula — focal injection, sun exposure, lateral or nasal

Within the conjunctivitis spectrum, distinguish:

Non-infectious, non-allergic conjunctival inflammation:

Key distinction: Bilateral itching + ropy discharge + atopy → allergic. Unilateral with vesicles on lid + dendrites → HSV (NO steroids). Hyperacute copious purulence → gonococcal (systemic ceftriaxone). Chronic mucopurulent in young sexually active adult → chlamydial (azithromycin PO + partner treatment).

Board pearl: When a contact lens wearer in the stem develops "red eye with pain," do not select bacterial conjunctivitis — the answer is almost always microbial (often pseudomonal) keratitis, and the correct next step is discontinue lenses + same-day ophthalmology + culture-guided fortified topical antibiotics, not pharmacy-counter erythromycin.

Differentials — Other Red-Eye Syndromes to Exclude

— Sudden severe pain, halos around lights, headache, nausea/vomiting

— Mid-dilated, fixed pupil; rock-hard globe; cloudy cornea

— Emergency: IV acetazolamide, topical β-blocker, pilocarpine, mannitol; definitive laser peripheral iridotomy

— Painful red eye, photophobia, decreased vision

— Ciliary flush, cells/flare in anterior chamber, miotic pupil

— Associations: HLA-B27 spondyloarthropathies, sarcoidosis, IBD, syphilis, TB

— Treatment by ophthalmology: topical steroids + cycloplegic

— Bacterial (contact lens), HSV (dendrite), fungal (vegetative trauma), Acanthamoeba (water exposure with lenses — severe pain out of proportion)

— Fluorescein staining + slit-lamp + corneal scraping

— Episcleritis: sectoral injection, mild discomfort, blanches with phenylephrine, self-limited

— Scleritis: severe boring pain (wakes from sleep), violaceous hue, does NOT blanch — associated with RA, GPA, relapsing polychondritis; needs systemic NSAIDs or immunosuppression

— Painless, blood under conjunctiva, often after Valsalva, cough, anticoagulation

— No treatment; resolves in 1–2 weeks; check BP and INR if on warfarin

— Preseptal: lid swelling/erythema, no proptosis, no EOM restriction, no vision change — oral antibiotics

— Orbital: proptosis, pain with EOM, ophthalmoplegia, vision change, fever — CT orbits, IV antibiotics, ENT/ophthalmology

— Bilateral grittiness, worse with screen use/wind, Schirmer's test low

— Treat with artificial tears, cyclosporine/lifitegrast, punctal plugs

Acute angle-closure glaucoma:

Anterior uveitis (iritis):

Keratitis:

Episcleritis vs scleritis:

Subconjunctival hemorrhage:

Preseptal vs orbital cellulitis:

Dry eye disease:

Key distinction: Pain + photophobia + decreased vision + ciliary flush = NOT conjunctivitis. This triad must trigger consideration of keratitis, uveitis, scleritis, or angle-closure glaucoma — all of which require ophthalmology, not topical antibiotics. Conjunctivitis is the diagnosis of a comfortable, seeing eye with discharge or itching.

Secondary Prevention, Discharge Instructions, Long-Term Plan

— Strict hand hygiene; wash hands before/after touching eyes

— Do not share towels, washcloths, pillows, eye makeup, or contact lenses

— Discard eye makeup used during the infection

— Do not wear contact lenses until symptoms fully resolved + 24 h after completing antibiotics

— Replace contact lens case and discard current lens pair

— Avoid eye rubbing

— Return precautions: worsening pain, vision change, photophobia, no improvement at 48–72 h

— Highly contagious for up to 2 weeks

— Stay home from work/school per institutional policy (especially healthcare workers — usually until discharge resolves)

— Disinfect surfaces, doorknobs, phones

— Symptoms peak at 4–7 days, full resolution by 2–3 weeks

— Improvement expected in 48–72 h; complete full antibiotic course

— Reasonable to return to work/school 24 h after starting antibiotics (per local policy)

— Allergen avoidance: pollen counts, HEPA filters, dust mite covers, pet dander control

— Pre-season prophylaxis: start mast cell stabilizer 2 weeks before allergy season

— Daily preservative-free artificial tears for dilution effect

— Avoid contact lens use during high-allergen periods

— Allergy referral if poorly controlled; consider immunotherapy

— Test and treat all sexual partners from prior 60 days

— Screen for HIV, syphilis, hepatitis B/C

— Report per state public health requirements

— Repeat testing in 3 months to assess reinfection

Discharge counseling for ALL conjunctivitis patients:

Viral-specific instructions:

Bacterial-specific instructions:

Allergic prevention strategies:

STI follow-up (gonococcal/chlamydial):

Step 3 management: When discharging a patient with bacterial conjunctivitis, specifically counsel on contact lens disposal and case replacement — recurrence is overwhelmingly driven by reintroduction from contaminated lens cases. Document this counseling; it's a frequent quality measure and a tested point on Step 3 vignettes about recurrent conjunctivitis.

Follow-Up, Monitoring, and Counseling

— Uncomplicated bacterial: follow-up only if no improvement at 48–72 h

— Uncomplicated viral: reassure self-limited course; return if not improving by 2 weeks or worsening at any point

— Allergic: reassess in 2–4 weeks for treatment response; consider step-up therapy

— Gonococcal: clinical reassessment in 24–48 h; test-of-cure for chlamydia/GC NAAT in 3 months (reinfection screening)

— Worsening pain

— Decreased or blurred vision not cleared by blinking

— Photophobia

— Increased discharge after 72 h of treatment

— Periorbital swelling, fever

— HEDIS-style metric: avoidance of unnecessary antibiotics for viral conjunctivitis — major outpatient antimicrobial stewardship target

— Document etiologic reasoning before prescribing topical antibiotics

— Use of generic erythromycin or polymyxin-trimethoprim preferred over branded fluoroquinolones for cost-effectiveness

— Replace lenses per manufacturer schedule; never sleep in non–extended-wear lenses

— Never rinse lenses with tap water (Acanthamoeba risk)

— Replace case every 3 months

— Daily disposable lenses lowest infection risk

— Annual eye exam with contact lens prescription update

— Coordinate with primary atopic disease management (asthma, eczema, rhinitis) — shared treatment strategy

— Consider sublingual or subcutaneous immunotherapy for refractory cases with identifiable triggers (3–5 year course)

— Monitor for steroid-induced IOP rise if chronic ophthalmic steroid use — annual ophthalmology with tonometry

Routine follow-up cadence:

Red-flag teaching for return visit:

Quality and value-based metrics:

Contact-lens counseling (longitudinal):

Allergic conjunctivitis longitudinal care:

CCS pearl: Schedule a 48–72 hour follow-up phone call or visit after starting topical antibiotics for bacterial conjunctivitis. On CCS, "schedule follow-up visit" actions accumulate management points; failure to arrange follow-up after empirical therapy is a recurring point loss. For viral cases, telephone follow-up at 1 week is equally appropriate and avoids unnecessary clinic visits while ensuring red-flag screening.

Ethical, Legal, and Patient Safety Considerations

— Gonococcal and chlamydial conjunctivitis are reportable STIs in all US states — report to public health within required timeframe

— Neonatal gonococcal ophthalmia: report and investigate maternal prenatal care; involves social work and public health follow-up of mother and partners

— Pediatric STI in non-neonatal child: triggers mandatory child abuse evaluation and reporting to Child Protective Services — chlamydial or gonococcal conjunctivitis in a child older than vertical-transmission window is a sentinel finding

— Expedited partner therapy (EPT) is legal in most states for chlamydia (and gonorrhea in some)

— Maintain confidentiality of the index patient; do not disclose identity to partners contacted via public health

— Erythromycin oral therapy for chlamydial conjunctivitis in infants <6 weeks carries a small association with infantile hypertrophic pyloric stenosis — counsel parents on signs (projectile non-bilious vomiting) and return precautions; document discussion

— Use of topical steroids carries risks (cataract, glaucoma, HSV reactivation) — should be ophthalmologist-prescribed with documented IOP monitoring plan

— Patients discharged from urgent care with "conjunctivitis" but unrecognized keratitis/uveitis represent a major diagnostic-error liability — always document visual acuity and fluorescein exam before assigning the diagnosis

— Contact lens wearers triaged to virtual visits without slit-lamp exam are high-risk for missed microbial keratitis — establish clear policy to see in person

— Communicate culture/NAAT results to patients within a defined timeframe; document patient notification (Joint Commission standard)

— Healthcare workers with adenoviral conjunctivitis must be excluded from patient contact until discharge resolves

— Outbreak in clinic or daycare: contact local public health, enhance environmental cleaning of tonometers, slit lamps, doorknobs

Mandatory reporting:

Partner notification and confidentiality:

Informed consent edge cases:

Transition-of-care risks:

Public health and infection control:

Board pearl: Chlamydial or gonococcal conjunctivitis in a non-neonatal child is presumptive evidence of sexual abuse until proven otherwise — mandatory reporting to CPS, social work involvement, and a complete forensic evaluation are required. This is a frequently tested ethical scenario on Step 3.

High-Yield Associations and Rapid-Fire Facts

— Itching → allergic

— Mattering/glued lids → bacterial

— Watery + preauricular node → viral (adenoviral)

— Hyperacute copious pus → gonococcal

— Chronic mucopurulent in sexually active adult → chlamydial

— Contact lens + pain → keratitis, not conjunctivitis

— Adenovirus serotypes 8, 19, 37 → epidemic keratoconjunctivitis (EKC)

— Adenovirus serotypes 3, 7 → pharyngoconjunctival fever (fever + pharyngitis + conjunctivitis)

— H. influenzae nontypeable → most common pediatric bacterial cause; associated with otitis media (conjunctivitis-otitis syndrome)

— Chlamydia trachomatis serovars A–C → trachoma; D–K → adult inclusion conjunctivitis and neonatal

— N. gonorrhoeae → only bacterium that penetrates intact cornea

— Pseudomonas aeruginosa → contact-lens keratitis, hypopyon

— Acanthamoeba → severe pain out of proportion, lens worn in tap water/swimming

— Erythromycin ointment — newborn prophylaxis in all US states

— Olopatadine — first-line allergic

— Fluoroquinolone drops — contact-lens bacterial conjunctivitis

— Never use topical anesthetics for take-home symptom relief

— Topical steroids — ophthalmology only

— Reactive arthritis (Reiter): conjunctivitis + urethritis + arthritis ("can't see, can't pee, can't climb a tree")

— Kawasaki disease: bilateral non-exudative conjunctival injection, fever ≥5 days, strawberry tongue, rash, cervical adenopathy, extremity changes

— Sjögren's: keratoconjunctivitis sicca + xerostomia

— Stevens-Johnson syndrome: severe membranous conjunctivitis with skin/mucosal involvement

Discriminator cheat sheet:

Pathogen pearls:

Drug pearls:

Exam-tested syndromic packages:

Board pearl: Bilateral non-exudative ("limbal-sparing") conjunctival injection in a febrile child should trigger Kawasaki disease workup — echocardiogram, ESR/CRP, platelets — NOT topical antibiotics. Missing the diagnosis risks coronary artery aneurysm; IVIG plus aspirin must be started within 10 days.

Board Question Stem Patterns

— "A 22-year-old with eczema and seasonal rhinitis presents with bilateral itchy, watery eyes for 3 days each spring. Exam: chemosis, stringy mucoid discharge, no preauricular nodes."

— Answer: olopatadine drops + allergen avoidance + cold compresses + preservative-free artificial tears

— "A 30-year-old teacher with URI symptoms develops unilateral watery red eye that becomes bilateral over 2 days. Tender preauricular node. Visual acuity 20/25."

— Answer: supportive care, hand hygiene, no antibiotics; school exclusion until discharge resolves

— "A 35-year-old with right eye glued shut on awakening for 3 days. Yellow-green discharge. No pain, vision 20/20."

— Answer: erythromycin or polymyxin-trimethoprim drops × 5–7 days

— "A 24-year-old contact lens wearer with red painful right eye and decreased vision. Slit lamp: corneal infiltrate."

— Answer: discontinue lenses + same-day ophthalmology + fluoroquinolone drops + culture — NOT routine bacterial conjunctivitis management

— "A 28-year-old sexually active man with sudden copious purulent right eye discharge over 12 h, lid swelling, preauricular node."

— Answer: IM ceftriaxone + doxycycline + saline lavage + ophthalmology + STI workup + partner notification

— "5-day-old with bilateral mucopurulent eye discharge; mother had no prenatal care."

— Answer: conjunctival Gram stain/culture/NAAT for GC and CT; IV/IM ceftriaxone if GC; oral erythromycin if chlamydial; admit

— "4-year-old with bilateral purulent conjunctivitis and otalgia."

— Answer: oral amoxicillin-clavulanate (covers H. influenzae); topical antibiotics not needed

— "Young man with conjunctivitis, dysuria, asymmetric oligoarthritis post-dysentery."

— Answer: reactive arthritis; treat underlying infection (often chlamydia), NSAIDs

Stem pattern 1 — Allergic conjunctivitis:

Stem pattern 2 — Viral (adenoviral):

Stem pattern 3 — Bacterial in adult:

Stem pattern 4 — Contact lens wearer:

Stem pattern 5 — Hyperacute gonococcal:

Stem pattern 6 — Neonatal:

Stem pattern 7 — Conjunctivitis-otitis:

Stem pattern 8 — Reactive arthritis:

Board pearl: When the answer choices include "topical antibiotic" for an obvious viral or allergic stem, the trap is to treat. Step 3 rewards antimicrobial stewardship — choose supportive care, document the rationale, and counsel the patient on natural history and red flags.

One-Line Recap

Conjunctivitis is a clinical diagnosis triaged into viral (watery + preauricular node, supportive), bacterial (purulent + glued lids, topical antibiotics — fluoroquinolone if contact lens), or allergic (bilateral itching + atopy, olopatadine) — but any red eye with pain, photophobia, decreased vision, or contact-lens use must be referred to ophthalmology to exclude keratitis, uveitis, or angle-closure before assigning the conjunctivitis label.

— Itching = allergic

— Mattering/glued lids = bacterial

— Preauricular node = viral (or gonococcal)

— Hyperacute purulence → gonococcal (IM ceftriaxone, same-day ophthalmology)

— Contact lens + pain → microbial keratitis, not conjunctivitis

— Dendrite on fluorescein → HSV keratitis (NO steroids)

— Mid-dilated fixed pupil + halos + headache → acute angle-closure glaucoma

— Proptosis + pain with EOM → orbital cellulitis (CT, IV antibiotics)

— Most viral and allergic conjunctivitis receive unnecessary antibiotics

— First-line bacterial drops: erythromycin ointment or polymyxin-trimethoprim

— Reserve fluoroquinolones for contact lens wearers

— Never use topical steroids in primary care for red eye

— Never prescribe take-home topical anesthetics

— Document visual acuity and fluorescein exam on every red eye

— Counsel on hand hygiene, contact lens disposal, case replacement

— Mandatory reporting for gonococcal/chlamydial cases; CPS evaluation for non-neonatal pediatric STI conjunctivitis

— 48–72 hour follow-up for bacterial cases; return precautions for vision change, pain, photophobia in all cases

Discriminator triad to memorize:

Cannot-miss emergencies hiding in red-eye stems:

Antimicrobial stewardship is the tested principle:

Step 3 management essentials: