Study guide
19.1 The Acute Red Eye & Ophthalmic Emergencies
ABIM Internal Medicine Exam
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1 Chapter 0: The ABIM Exam, Blueprint & Study Strategy
0.1 Exam Format, Question Types & the 2026 Blueprint 0.2 Eligibility, Registration, Fees & Exam-Day Logistics 0.3 Scoring, the Passing Standard & Score Reports 0.4 Building a Blueprint-Weighted Study Plan
2 Chapter 1: Cardiovascular Disease (14% of Exam)
1.1 Ischemic Heart Disease & Acute Coronary Syndromes 1.2 Antithrombotic Therapy, Secondary Prevention & Mechanical Complications of MI 1.3 Atrial Fibrillation, Atrial Flutter & Stroke Prevention 1.4 Supraventricular Tachycardias, Ventricular Arrhythmias & Bradycardias 1.5 Heart Failure: Classification, Staging & Guideline-Directed Medical Therapy 1.6 Device Therapy, HFpEF & the Cardiomyopathies 1.7 Valvular Heart Disease & Endocarditis Prophylaxis 1.8 Pericardial Disease & Acute Aortic Syndromes 1.9 Hypertension: Classification, Diagnosis & Secondary Causes 1.10 Hypertensive Crises & Dyslipidemia 1.11 Adult Congenital Heart Disease & Coarctation of the Aorta 1.12 Syncope: Reflex, Orthostatic & Cardiac Causes 1.13 Cardiac Physical Examination, Murmurs & Antithrombotic Selection
3 Chapter 2: Endocrinology, Diabetes & Metabolism (9% of Exam)
2.1 Diabetes Mellitus: Diagnosis, Glycemic Targets & Pharmacotherapy 2.2 Insulin Therapy, Hyperglycemic Emergencies & Chronic Complications 2.3 Thyroid Function Testing & Hypothyroidism 2.4 Thyrotoxicosis, Thyroid Storm & Thyroid Nodules 2.5 Adrenal & Pituitary Disorders 2.6 Hypercalcemia, Hypocalcemia & Disorders of Mineral Metabolism 2.7 Osteoporosis & Paget Disease of Bone 2.8 Ovarian, Testicular & Reproductive Endocrine Disorders 2.9 Hypoglycemia, Endocrine Tumors, Polyglandular Syndromes & Severe Hypertriglyceridemia
4 Chapter 3: Gastroenterology & Hepatology (9% of Exam)
3.1 Esophageal Disease 3.2 Stomach & Duodenal Disease and Gastrointestinal Hemorrhage 3.3 Inflammatory Bowel Disease 3.4 Celiac Disease & Irritable Bowel Syndrome 3.5 Diverticular Disease & Colorectal Cancer Screening 3.6 Viral Hepatitis, Steatotic & Alcohol-Associated Liver Disease 3.7 Cirrhosis & the Complications of Portal Hypertension 3.8 Acute Pancreatitis 3.9 Chronic Pancreatitis & Biliary Tract Disease 3.10 Inherited, Autoimmune & Drug-Induced Liver Disease 3.11 Small Intestinal Disease, Ischemia & Gastrointestinal Complications of HIV
5 Chapter 4: Infectious Disease (9% of Exam)
4.1 Lower Respiratory Tract Infections & Sepsis Syndromes 4.2 Viral Respiratory Pathogens & Tuberculosis 4.3 Central Nervous System Infections 4.4 Skin, Soft Tissue, Bone & Joint Infections 4.5 Infective Endocarditis & Cardiovascular Infection 4.6 Clostridioides difficile & Catheter-Related Bloodstream Infection 4.7 HIV Diagnosis, Antiretroviral Therapy & Prevention 4.8 Opportunistic Infections & Sexually Transmitted Infections 4.9 Fever of Unknown Origin, Neutropenic Fever & Toxic Shock 4.10 Travel-Related Illness, Vector-Borne Disease & Outbreaks 4.11 Infection Prevention, Nosocomial Infection & Postexposure Prophylaxis 4.12 Rheumatic Fever, Poststreptococcal Disease, Enteric & Hepatic Infections
6 Chapter 5: Pulmonary Disease (9% of Exam)
5.1 COPD: Diagnosis, GOLD Classification & Initial Pharmacotherapy 5.2 Interventions That Reduce COPD Mortality & Exacerbation Management 5.3 Asthma: Diagnosis, Stepwise Therapy & Status Asthmaticus 5.4 Interstitial Lung Disease & Idiopathic Pulmonary Fibrosis 5.5 Sarcoidosis, Hypersensitivity Pneumonitis & Occupational Lung Disease 5.6 Pulmonary Embolism: Diagnosis, Risk Stratification & Anticoagulation 5.7 Pulmonary Hypertension & Sleep-Disordered Breathing 5.8 Acute Respiratory Distress Syndrome & Mechanical Ventilation 5.9 Pleural Disease, Empyema & Pneumothorax 5.10 Bronchiectasis, Cystic Fibrosis & Restrictive Lung Disease 5.11 Evaluation of Cough, Dyspnea, Hemoptysis & the Solitary Pulmonary Nodule
7 Chapter 6: Rheumatology & Orthopedics (9% of Exam)
6.1 Rheumatoid Arthritis: Diagnosis & Systemic Manifestations 6.2 Antirheumatic Pharmacotherapy & the Spondyloarthropathies 6.3 Gout: Pathophysiology & Acute Management 6.4 Urate-Lowering Therapy & Calcium Pyrophosphate Deposition Disease 6.5 Osteoarthritis 6.6 Systemic Lupus Erythematosus 6.7 Systemic Sclerosis, Sjogren Syndrome & Inflammatory Myopathies 6.8 The Vasculitides 6.9 Regional Musculoskeletal Syndromes, Back Pain & Sports Injuries 6.10 Other Primary Rheumatic Disorders & Mixed Connective Tissue Disease 6.11 Osteonecrosis & Metabolic Bone Disease
8 Chapter 7: Hematology (6% of Exam)
7.1 Approach to Anemia & the Microcytic Anemias 7.2 Macrocytic, Normocytic & Hemolytic Anemias 7.3 Hemoglobinopathies, Thalassemias & Paroxysmal Nocturnal Hemoglobinuria 7.4 Platelet Disorders, Thrombocytopenia & the Bleeding Patient 7.5 Coagulation Factor Disorders, Thrombophilia & Anticoagulant Reversal 7.6 Acute Leukemias, Chronic Leukemias & Myeloproliferative Neoplasms 7.7 Lymphomas & Plasma Cell Disorders 7.8 Myelodysplastic Syndrome, Myeloproliferative Neoplasms & Porphyria 7.9 Transfusion Medicine & Late Complications of Transplantation
9 Chapter 8: Medical Oncology (6% of Exam)
8.1 Breast, Lung, Colorectal & Prostate Cancer 8.2 Oncologic Emergencies 8.3 Genitourinary & Gynecologic Malignancies 8.4 Head and Neck, Bone & Soft Tissue Cancer and Cancer of Unknown Primary 8.5 Complications of Cancer & Its Treatment 8.6 Cancer Prevention, Survivorship & Psychosocial Care
10 Chapter 9: Nephrology & Urology (6% of Exam)
9.1 Acute Kidney Injury: Staging, Etiology & Urine Microscopy 9.2 Glomerular Disorders & Nephrotic Syndrome 9.3 Nephritic Syndromes, RPGN & Indications for Renal Replacement Therapy 9.4 Chronic Kidney Disease: Staging & Progression Retardation 9.5 Complications of Chronic Kidney Disease: Anemia, CKD-MBD & Acidosis 9.6 Hyponatremia, Hypernatremia & Water Balance 9.7 Potassium Disorders & Systematic Acid-Base Analysis 9.8 Renal Tubular Acidosis & Nephrolithiasis 9.9 Prostate Disorders, Urinary Incontinence & Other Urologic Conditions 9.10 Cystic Kidney Disease, Obstructive Uropathy, Tubulointerstitial Disease & Hematuria
11 Chapter 10: Neurology (4% of Exam)
10.1 Acute Ischemic Stroke: Syndromes & Reperfusion 10.2 Transient Ischemic Attack, Secondary Prevention & Hemorrhagic Stroke 10.3 Headache & Facial Pain 10.4 Seizures, Epilepsy & Movement Disorders 10.5 Multiple Sclerosis & Neuromuscular Junction Disorders 10.6 Motor Neuron Disease & Acute Peripheral Neuropathy 10.7 Cranial Neuropathies & Neuro-Ophthalmology 10.8 Peripheral Neuropathies, CNS Tumors & Other Neurologic Disorders
12 Chapter 11: Psychiatry & Behavioral Health (4% of Exam)
11.1 Major Depressive Disorder & Medical Mimics 11.2 Antidepressant Pharmacotherapy & Treatment-Resistant Depression 11.3 Bipolar Disorder, Mood Stabilizers & Lithium Toxicity 11.4 Anxiety, Stress-Related & Obsessive-Compulsive Disorders 11.5 Alcohol Use Disorder & Withdrawal 11.6 Pharmacotherapy for Alcohol & Opioid Use Disorder 11.7 Toxidromes, Psychiatric Emergencies & Suicide Risk Assessment 11.8 Psychotic, Somatic Symptom, Factitious & Personality Disorders 11.9 Eating Disorders, Sleep Disorders & Sexual Health
13 Chapter 12: Dermatology (3% of Exam)
12.1 Dermatitis, Papulosquamous & Inflammatory Dermatoses 12.2 Acne, Rosacea & Cutaneous Infections 12.3 Herpes Zoster & Autoimmune Blistering Diseases 12.4 Nodules, Tumors & Cutaneous Oncology 12.5 Dermatologic Emergencies & Severe Cutaneous Adverse Reactions 12.6 Pigment Disorders, Alopecia, Nail Disease & Photosensitivity 12.7 Vascular Dermatoses, Environmental Injury & Cutaneous Signs of Systemic Disease
14 Chapter 13: Obstetrics & Gynecology / Women's Health (3% of Exam)
13.1 Contraception, Preconception Care & Teratogenicity 13.2 Hypertensive Disorders of Pregnancy & Gestational Diabetes 13.3 Thyroid Disease & Venous Thromboembolism in Pregnancy 13.4 Menopause & Menopausal Hormone Therapy 13.5 Abnormal Uterine Bleeding, Endometrial Disease & Gynecologic Cancer Screening 13.6 Breast Disorders & Diseases of the Vulva and Vagina 13.7 Menstrual Disorders, Fibroids, Endometriosis & Early Pregnancy Complications
15 Chapter 14: Geriatric Syndromes (3% of Exam)
14.1 Comprehensive Geriatric Assessment & Frailty 14.2 Falls, Gait Assessment & Polypharmacy 14.3 Urinary Incontinence & Pressure Injuries in Older Adults 14.4 Mild Cognitive Impairment, Dementia & Its Subtypes 14.5 Delirium & the Pharmacotherapy of Cognitive Disorders 14.6 Palliative Care, Hospice & Advance Care Planning 14.7 Chronic Wounds, Nutrition, Swallowing, Constipation & Hip Fracture 14.8 Sensory Impairment, Dizziness, Elder Mistreatment & Care Settings
16 Chapter 15: Allergy & Immunology (2% of Exam)
15.1 Anaphylaxis: Recognition & Emergency Management 15.2 Urticaria & Angioedema 15.3 Drug Allergy, Desensitization & Adult Immunodeficiency 15.4 Food Allergy, Insect Venom Hypersensitivity, Serum Sickness & Contrast Reactions 15.5 Rhinitis, Conjunctivitis, Eosinophilic & Mast Cell Disorders
17 Chapter 16: Preventive Medicine, Immunization & Clinical Epidemiology
16.1 The USPSTF Framework & Evidence-Based Cancer Screening 16.2 Cardiovascular & Metabolic Screening and Primary Prevention 16.3 Adult Immunization & Vaccines in Special Populations 16.4 Clinical Epidemiology, Biostatistics & Study Design
18 Chapter 17: Miscellaneous - Ethics, Patient Safety & Quality Improvement (2% of Exam)
17.1 Principles of Bioethics & Decisional Capacity 17.2 Informed Consent, Treatment Refusal & Special Scenarios 17.3 Surrogate Decision-Making, Advance Directives & Confidentiality 17.4 Patient Safety Science, Medical Error & Diagnostic Reasoning 17.5 Quality Improvement Methods, Health Disparities & Health Equity
19 Chapter 18: Perioperative Medicine & Medical Consultation
18.1 Preoperative Cardiovascular Risk Assessment 18.2 Preoperative Pulmonary Risk & Perioperative Medication Management 18.3 Perioperative Anticoagulation, Bridging & Postoperative Complications
20 Chapter 19: Ophthalmology (1% of Exam)
19.1 The Acute Red Eye & Ophthalmic Emergencies 19.2 Painless Vision Loss & Chronic Ophthalmic Disease 19.3 Uveitis, Scleritis & Orbital Disease
21 Chapter 20: Otolaryngology & Dental Medicine (1% of Exam)
20.1 Dizziness, Vertigo & Epistaxis 20.2 Ear Disorders, Hearing Loss & Upper Respiratory Infections 20.3 Oral Cavity, Salivary Gland, Laryngeal & Taste and Smell Disorders
19.1 The Acute Red Eye & Ophthalmic Emergencies
Key Takeaways Explain This Topic AI
Conjunctivitis, glaucoma, cataracts, diseases of the cornea, neuro-ophthalmology, retinal disease, uveitis and miscellaneous disorders are the eight enumerated Ophthalmology subsections.
Vision loss, severe pain, photophobia, a fixed mid-dilated pupil or ciliary flush indicate a sight-threatening cause rather than conjunctivitis.
Acute angle-closure glaucoma presents with a painful red eye, halos, nausea and a mid-dilated non-reactive pupil and requires emergent pressure reduction.
Contact lens wearers with a corneal infiltrate require cultures and intensive topical antibiotics, and lenses must be discontinued.
Topical corticosteroids and topical anesthetics must not be prescribed for self-administration because they impair healing and mask progression.
Last updated: August 2026
Ophthalmic emergencies and vision-threatening disorders frequently present to primary care, urgent care, and inpatient internal medicine services. An internist must be adept at rapidly distinguishing benign, self-limiting superficial conditions from sight-threatening emergencies requiring immediate intraocular pressure reduction, antimicrobial pharmacotherapy, high-dose systemic corticosteroids, or emergent vitreoretinal surgery.
1. Acute Red Eye Triage & Differential Diagnosis
The initial evaluation of the acute red eye begins with four critical triage questions:
Is there vision loss or decreased visual acuity? (Suggests keratitis, anterior uveitis, acute glaucoma, or endophthalmitis)
Is there severe, deep, aching, or boring eye pain? (Suggests scleritis, anterior uveitis, acute angle-closure glaucoma, or corneal ulceration)
Is there marked photophobia? (Suggests corneal epithelial defect, keratitis, or anterior uveitis)
Is the pupil abnormal (fixed, mid-dilated, or irregular/constricted)? (Suggests acute angle-closure glaucoma or anterior uveitis with posterior synechiae)
Condition Primary Symptoms Physical / Slit-Lamp Findings Pupil & IOP Status First-Line Management
Viral Conjunctivitis Gritty sensation, watery discharge, bilateral (sequential) Follicles on palpebral conjunctiva, preauricular lymphadenopathy Normal pupil; Normal IOP Supportive care, cold compresses, strict hand hygiene
Bacterial Conjunctivitis Copious purulent discharge , morning eyelid matting/crusting Marked conjunctival injection; absence of preauricular adenopathy Normal pupil; Normal IOP Topical Fluoroquinolone (Ofloxacin 0.3%, Moxifloxacin 0.5%) or Polymyxin B-Trimethoprim drops for 5–7 days
Hyperacute Gonococcal Conjunctivitis Explosive, severe, thick purulent drainage; rapid progression Marked chemosis, lid edema; risk of rapid corneal melting and perforation Normal pupil initially; elevated IOP if complicated IM Ceftriaxone 1 g single dose + copious continuous saline eye irrigation + oral Azithromycin 1 g (for chlamydia co-treatment)
Allergic Conjunctivitis Intense bilateral pruritus (hallmark) , watery/stringy discharge Chemosis, diffuse hyperemia, cobblestone papillae on upper tarsus Normal pupil; Normal IOP Topical dual-action mast cell stabilizer/antihistamine ( Olopatadine 0.1–0.2% or Ketotifen 0.025% )
Corneal Abrasion Sudden sharp pain, foreign body sensation, photophobia, tearing Fluorescein uptake under cobalt blue light (linear/geographic epithelial defect) Normal to reactive constricted pupil; Normal IOP Non-contact lens: Erythromycin ointment. Contact lens wearer: Topical antipseudomonal drops (Ciprofloxacin 0.3% or Tobramycin); NEVER PATCH
Herpes Simplex Keratitis Pain, foreign body sensation, photophobia, red eye Dendritic branching ulcer with terminal end-bulbs on fluorescein stain; reduced corneal sensation Normal pupil; IOP normal or elevated Topical Trifluridine 1% or Ganciclovir 0.15% gel OR Oral Valacyclovir 500–1000 mg TID . CONTRAINDICATION: Topical Corticosteroids
Anterior Uveitis (Iritis) Deep aching pain, consensual photophobia , blurred vision Ciliary flush (violaceous circumcorneal injection), cells and flare in anterior chamber, keratic precipitates, hypopyon Constricted, sluggish, or irregular pupil (posterior synechiae); Variable IOP Urgent ophthalmology referral; Topical Corticosteroids (Prednisolone acetate 1%) + Cycloplegic/Mydriatic drops (Homatropine 5% or Cyclopentolate 1%)
Acute Angle-Closure Glaucoma Sudden excruciating eye/head pain, nausea/vomiting, colored halos Cloudy / steamy cornea , shallow anterior chamber, ciliary flush, firm "rock-hard" globe Fixed, mid-dilated non-reactive pupil ; IOP markedly elevated (>40–70 mmHg) EMERGENCY: Topical Timolol 0.5% + Apraclonidine 1% + Pilocarpine 2% + Systemic IV/Oral Acetazolamide 500 mg or IV Mannitol 1–2 g/kg ; Definitive: Laser Peripheral Iridotomy
Episcleritis Mild discomfort, foreign body sensation, no severe pain Localized sectoral, salmon-pink injection; vessels blanch with topical 2.5% Phenylephrine Normal pupil; Normal IOP Self-limiting (1–2 weeks); artificial tears, topical/oral NSAIDs
Scleritis Severe, deep, boring pain radiating to forehead/jaw, wakes patient from sleep Deep violaceous/bluish hue, scleral edema; vessels do NOT blanch with 2.5% Phenylephrine ; scleral thinning Normal or reactive pupil; Normal IOP Urgent ophthalmology referral; Systemic NSAIDs , Oral Prednisone 1 mg/kg/day , DMARDs/Biologics (Rituximab, Infliximab); workup for RA, GPA, SLE
Loading diagram... Emergency Diagnostic & Management Triage for the Acute Red Eye
- 2. In-Depth Management of Specific Ophthalmic Conditions
- Acute Angle-Closure Glaucoma (AACG)
Pathophysiology: Narrowing or closure of the anterior chamber angle between the peripheral iris and trabecular meshwork, preventing aqueous humor outflow through the canal of Schlemm. Most commonly triggered by pupillary dilation (mydriasis in dim lighting, emotional stress, or pharmacologic mydriatics/anticholinergics such as atropine, ipratropium, oxybutynin, tricyclic antidepressants, topiramate, or sympathomimetics) in anatomically predisposed eyes (hyperopia, shallow anterior chambers, advancing age, Asian or Inuit ancestry).
Diagnostic Confirmation: Tonometry revealing Intraocular Pressure (IOP) markedly elevated above normal (10–21 mmHg), typically reaching 40 to 70 mmHg . Direct visualization of shallow anterior chamber and closed angle via gonioscopy (performed by ophthalmology).
Emergency IOP-Lowering Pharmacotherapy Protocol:
Topical Beta-Blocker: Timolol 0.5% ophthalmic solution (1 drop) — suppresses aqueous humor production by ciliary epithelium.
Topical Alpha-2 Adrenergic Agonist: Apraclonidine 1% or Brimonidine 0.2% (1 drop) — dual action: reduces aqueous humor production and increases uveoscleral outflow.
Topical Cholinergic / Miotic Agent: Pilocarpine 2% (1 drop every 15 minutes for 2 doses) — stimulates pupillary sphincter muscle contraction to physically pull the peripheral iris away from the trabecular meshwork, opening the filtration angle. Clinical Pearl: Pilocarpine is ineffective when IOP >40–50 mmHg due to pressure-induced ischemia of the pupillary sphincter; administer after initiating pressure-lowering systemic agents.
Systemic Carbonic Anhydrase Inhibitor: Acetazolamide 500 mg IV or PO (followed by 250 mg PO QID) — rapidly halts aqueous humor production via carbonic anhydrase inhibition. (Check for severe sulfonamide allergy and avoid in sickle cell disease where acetazolamide induces sickling in the anterior chamber).
Systemic Hyperosmotic Agent (for refractory IOP): Intravenous Mannitol 1.0–2.0 g/kg IV over 30–45 minutes — increases serum osmolality to draw water out of the vitreous humor, reducing intraocular volume.
Definitive Treatment: Laser Peripheral Iridotomy (LPI) to create a full-thickness bypass hole in the peripheral iris, restoring aqueous flow. Prophylactic LPI is mandatory in the unaffected contralateral eye due to high rates (>50%) of subsequent angle-closure.
Herpes Simplex Keratitis vs Herpes Zoster Ophthalmicus
Herpes Simplex Keratitis (HSV-1):
Reactivation of latent HSV-1 from the trigeminal ganglion migrating down the ophthalmic branch (V1).
Hallmark Finding: Branching dendritic ulcer with rounded terminal bulbs on fluorescein staining, accompanied by reduced corneal sensation (neurotrophic cornea).
Treatment: Topical antivirals ( Ganciclovir 0.15% ophthalmic gel 5 times daily or Trifluridine 1% drops 8–9 times daily) OR systemic oral antivirals ( Valacyclovir 1000 mg PO TID or Acyclovir 400 mg PO 5 times daily for 10–14 days).
Critical Board Warning: NEVER USE TOPICAL CORTICOSTEROIDS in active epithelial dendritic keratitis. Corticosteroids potentiate viral replication, causing rapid transition into massive "geographic" corneal ulcers, corneal stromal melting, secondary bacterial superinfection, and permanent blindness.
Herpes Zoster Ophthalmicus (HZO):
Reactivation of Varicella-Zoster Virus in the ophthalmic division of the trigeminal nerve (CN V1).
Hutchinson Sign: Vesicles involving the tip, side, or ala of the nose , indicating nasociliary branch involvement; correlates with a >75% risk of intraocular complications (keratitis, anterior uveitis, secondary glaucoma, acute retinal necrosis).
Slit-Lamp: "Pseudodendrites" (elevated mucous plaques without terminal bulbs that stain poorly with fluorescein).
Treatment: Oral Valacyclovir 1000 mg PO TID for 7–10 days initiated within 72 hours of rash onset, combined with urgent ophthalmologic evaluation.
Episcleritis vs Scleritis
Episcleritis: Mild, self-limiting inflammation of the superficial episcleral vascular network. Features sectoral or diffuse salmon-pink injection. Phenylephrine 2.5% blanching test: Application of topical phenylephrine causes rapid blanching/constriction of episcleral vessels within 10–15 minutes, confirming superficial inflammation. Managed with cold compresses, artificial tears, or oral NSAIDs.
Scleritis: Severe, destructive, full-thickness inflammation of the deep sclera. Features excruciating, deep, boring pain radiating to the periorbital region, temple, or jaw that wakes the patient from sleep. Sclera demonstrates a distinct violaceous or bluish-red hue under natural light. Vessels DO NOT blanch with topical 2.5% Phenylephrine . Strongly associated with underlying systemic autoimmune diseases in >50% of cases ( Rheumatoid Arthritis [most common], Granulomatosis with Polyangiitis [GPA], Relapsing Polychondritis, Systemic Lupus Erythematosus). Complications include scleral thinning ( scleromalacia perforans ) and globe rupture. Managed with systemic high-dose NSAIDs, oral corticosteroids (Prednisone 1 mg/kg/day), and biologic immunosuppression (e.g., Rituximab, Infliximab).