Red eye

Conjunctival Causes

Viral conjunctivitis: Watery discharge, recent upper respiratory tract infection, highly contagious.
Bacterial conjunctivitis: Purulent discharge, eyelids sticking together, often unilateral.
Allergic conjunctivitis: Itchy, watery eyes, associated with other allergic symptoms like rhinitis.
Subconjunctival hemorrhage: Painless red eye, often spontaneous or following straining, no visual disturbance.
Dry eye syndrome: Burning, gritty sensation, worse with prolonged visual tasks, may be associated with systemic conditions like Sjögren’s syndrome.
Pterygium: Triangular fibrovascular growth on the conjunctiva, can be red and inflamed.

Corneal Causes

Keratitis: Painful red eye, photophobia, reduced vision, contact lens wear is a common risk factor.
Corneal ulcer: Severe pain, visual loss, white spot on the cornea, often related to trauma or contact lens use.
Corneal abrasion: History of trauma or foreign body, severe pain, photophobia, foreign body sensation.
Herpes simplex keratitis: Dendritic ulcer seen with fluorescein staining, history of cold sores.
Herpes zoster ophthalmicus: Vesicular rash in V1 distribution, pain, photophobia, Hutchinson’s sign (rash on the nose).
Contact lens-related infection: Associated with poor lens hygiene, can lead to microbial keratitis.

Uveal Causes

Anterior uveitis (iritis): Painful red eye, photophobia, small or irregular pupil, blurred vision, often associated with systemic autoimmune conditions.
Scleritis: Severe, deep eye pain, red eye, may be associated with systemic autoimmune diseases like rheumatoid arthritis.
Episcleritis: Localized redness, mild discomfort, usually self-limiting and not associated with systemic disease.
Acute angle-closure glaucoma: Sudden onset severe eye pain, headache, nausea, vomiting, blurred vision, halo around lights, mid-dilated non-reactive pupil.

History of Presenting Complaint

Onset: Acute onset suggests trauma, infection, or angle-closure glaucoma; gradual onset may suggest dry eye syndrome or conjunctivitis.
Pain: Severe pain suggests keratitis, uveitis, scleritis, or acute glaucoma; mild discomfort is more typical of conjunctivitis or episcleritis.
Photophobia: Common in keratitis and uveitis; less likely in conjunctivitis or episcleritis.
Discharge: Purulent suggests bacterial conjunctivitis; watery suggests viral or allergic conjunctivitis.
Visual disturbance: Blurred vision can occur in keratitis, uveitis, acute glaucoma, or corneal ulcer.
History of trauma: Foreign body sensation and history of trauma suggest corneal abrasion or foreign body.
Contact lens use: Increases the risk of keratitis, corneal ulcer, or infection.
Systemic symptoms: Fever, rash, or joint pain may indicate an underlying systemic condition like herpes zoster ophthalmicus or uveitis.
Previous eye conditions: Recurrent episodes suggest conditions like herpes simplex keratitis or chronic uveitis.
Medications: Recent use of eye drops, systemic medications, or anticoagulants may contribute to the condition.
Allergies: A history of allergies may suggest allergic conjunctivitis.
Occupation and hobbies: Exposure to chemicals, dust, or physical trauma may point towards specific causes.
Family history: Glaucoma, uveitis, or other eye conditions may have a genetic predisposition.
Recent travel: Exposure to pathogens or environmental factors abroad may be relevant.

Background

Medical history: Review for chronic conditions such as diabetes, rheumatoid arthritis, or hypertension, which may predispose to eye complications.
Surgical history: Previous eye surgeries, including LASIK or cataract surgery, may impact current eye health.
Medication history: Review for use of anticoagulants, corticosteroids, or eye drops.
Social history: Consider occupational hazards, smoking, alcohol use, and recreational drug use.
Family history: Assess for family history of glaucoma, autoimmune diseases, or hereditary eye conditions.
Environmental exposures: Assess for exposure to irritants, allergens, or infectious agents.
Immunization status: Consider relevant vaccinations, especially if infectious causes are suspected.
Trauma history: Review any recent or past trauma to the eye or face.
Previous imaging or investigations: Review any past imaging or specialist consultations.
Occupational and recreational history: To assess for risk factors such as prolonged screen time, outdoor activities, or swimming.

Laboratory Tests

Swab for culture and sensitivity: Particularly in cases of suspected bacterial conjunctivitis or corneal ulcer.
Viral PCR: If viral causes such as herpes simplex or zoster are suspected.
Complete blood count (CBC): To assess for infection or systemic involvement.
Autoimmune screen: Including ANA, ANCA, and rheumatoid factor if autoimmune uveitis or scleritis is suspected.
Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP): To assess for systemic inflammation.
Blood glucose levels: Particularly in diabetics, to rule out diabetic eye disease.
Thyroid function tests: In cases of suspected thyroid eye disease.
Venereal Disease Research Laboratory (VDRL) test or rapid plasma reagin (RPR): If syphilitic uveitis is suspected.
HLA-B27: If ankylosing spondylitis or reactive arthritis is suspected in cases of recurrent uveitis.
Tuberculosis (TB) screening: If TB-associated uveitis is suspected.
Serum ACE levels: If sarcoidosis is suspected as a cause of uveitis.
HIV test: In cases where immune compromise is suspected as a contributing factor.
Serum electrolytes: Particularly in cases with systemic symptoms or potential dehydration.
Blood cultures: If sepsis or endophthalmitis is suspected.

Imaging and Other Tests

Slit-lamp examination: Essential for diagnosing corneal, uveal, and conjunctival disorders.
Fluorescein staining: To identify corneal abrasions, ulcers, or herpetic keratitis.
Intraocular pressure (IOP) measurement: To assess for acute angle-closure glaucoma or ocular hypertension.
Ocular ultrasound: If there is concern for a posterior segment pathology not visible on slit-lamp examination.
Optical coherence tomography (OCT): To assess the retina and optic nerve in cases with visual disturbance.
Fundoscopy: To assess the retina, optic disc, and vessels for signs of systemic disease or retinal involvement.
CT or MRI orbit: If orbital cellulitis, abscess, or tumor is suspected.
Chest X-ray or CT chest: If sarcoidosis, TB, or other systemic causes are suspected.
B-scan ultrasonography: Useful in assessing the posterior segment in cases with opaque media or suspected retinal detachment.
Gonioscopy: To evaluate the anterior chamber angle in cases of suspected glaucoma.
Electroretinography (ERG): If retinal dystrophy or other retinal disorders are suspected.
Visual field testing: Particularly in cases with suspected glaucoma or optic neuropathy.
Ophthalmology referral: For any cases that are severe, recurrent, or not responding to initial treatment.

Musculoskeletal