The Daily Differential — Friday, May 22, 2026

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Hyphema

Blood in the anterior chamber can signal significant ocular trauma and can lead to acute glaucoma, corneal blood staining, rebleeding, and permanent vision...

At the Bedside

Mechanism: blunt trauma most common; also penetrating trauma, postoperative, neovascularization, anticoagulation, bleeding disorders.
Symptoms: eye pain, photophobia, blurred vision, visible blood layering in anterior chamber.
Exam priorities:
Visual acuity.
Inspect for open globe: teardrop pupil, Seidel positive, extrusion, severe subconjunctival hemorrhage, shallow/deep chamber asymmetry.
Slit lamp: anterior chamber blood layering or microhyphema with circulating RBCs.
Pupils, EOMs, consensual photophobia.
IOP measurement only if open globe is not suspected.
Grading:
Microhyphema: RBCs without visible layer.
Grade I: <1/3 anterior chamber.
Grade II: 1/3–1/2.
Grade III: >1/2 but not total.
Grade IV: total “8-ball” hyphema.
Workup:
CT orbits if significant trauma, concern for orbital fracture, intraocular foreign body, or open globe.
Consider CBC/coags if anticoagulated, bleeding disorder, nontraumatic hyphema.
Ask about sickle cell disease/trait — lower threshold for treatment/admission because RBC sickling obstructs trabecular meshwork at lower IOPs.
Initial ED management:
Eye shield; avoid patching that applies pressure.
Head of bed elevated 30–45 degrees.
Bed/activity restriction; avoid reading/straining if severe.
Pain control with acetaminophen/opioids if needed.
Antiemetics to prevent Valsalva and rebleed.
Avoid NSAIDs, aspirin, anticoagulants if medically safe.
Cycloplegics and topical steroids usually ophthalmology-directed.
Treat elevated IOP:
Topical beta blocker, alpha agonist, carbonic anhydrase inhibitor if no contraindications.
Avoid prostaglandins acutely unless ophthalmology directs.
Avoid/closely discuss acetazolamide and mannitol in sickle cell disease/trait due to acidosis/dehydration/osmotic effects worsening sickling; management threshold differs.
Disposition:
Urgent ophthalmology, typically same day or within 24 hours for small uncomplicated cases.
Admit/urgent intervention if: elevated IOP, sickle cell disease/trait, total/large hyphema, rebleeding, poor follow-up, pediatric/noncompliant patient, anticoagulation, suspected open globe, severe associated ocular injury.

A Classic Presentation

A 19-year-old is struck in the eye by a baseball and presents with photophobia and blurred vision. Exam shows VA 20/80, a layered blood level occupying 25% of the anterior chamber, no Seidel sign, and IOP 24 mmHg. He receives an eye shield, head elevation, acetaminophen, ondansetron, activity restriction, avoidance of NSAIDs, and urgent ophthalmology follow-up; sickle trait history is specifically assessed.

Study Directive

Draw the anterior chamber and label where blood obstructs the trabecular meshwork causing IOP rise.
Memorize admission triggers: sickle cell, high IOP, total hyphema, rebleed, poor follow-up, suspected globe injury.
Practice counseling script: no NSAIDs/aspirin, head elevation, eye shield, no strenuous activity, return for worse pain/vision/vomiting.
Review topical glaucoma medication contraindications, especially timolol in reactive airway disease/heart block.

Key Medications

Pain/nausea:
- Acetaminophen 650–1000 mg PO q6h PRN, max usually 3–4 g/day depending on risk factors.
- Ondansetron 4 mg IV/PO q6–8h PRN.
Cycloplegic, often ophthalmology-directed:
- Cyclopentolate 1% 1 drop BID–TID.
- Atropine 1% 1 drop daily–BID may be used for more severe inflammation; check ophthalmology preference.
Topical steroid, ophthalmology-directed:
- Prednisolone acetate 1% 1 drop QID or more frequently depending on severity — confirm with ophthalmology.
IOP-lowering agents:
- Timolol 0.5% 1 drop BID; avoid in asthma/COPD exacerbation, bradycardia, heart block.
- Brimonidine 0.2% 1 drop TID.
- Dorzolamide 2% 1 drop TID.
- Acetazolamide 500 mg PO/IV once, then 250 mg PO q6h if needed; avoid/consult ophtho in sickle cell disease/trait, sulfa allergy nuance, renal failure.
- Mannitol 0.5–1 g/kg IV for severe IOP elevation; avoid/consult in sickle cell disease/trait and CHF/renal failure.

High-Yield Pearls

Rebleeding risk peaks around days 2–5 and is often worse than the initial bleed.
Do not measure IOP if open globe is suspected.
In hyphema, the priorities are shield, elevate, quiet eye, control nausea/pain, and urgent ophthalmology.

Board Question

A patient with traumatic hyphema has elevated IOP. Which historical factor most strongly changes management by lowering the threshold for aggressive treatment/admission?

AMyopia
BSickle cell trait
CPrior LASIK surgery
DSeasonal allergies

Reveal answer

Correct: B

Sickle cell disease or trait increases risk of trabecular obstruction and optic nerve injury at lower IOPs. Carbonic anhydrase inhibitors and hyperosmotic agents may worsen sickling physiology and should be used only with ophthalmology guidance.

Recent Literature

Review or guideline Hyphema
Optom Clin, 1993 · cited 1×
Recent clinical Pediatric Hyphema
Pediatr Rev, 2026

3 of 4

Optic Neuritis

Optic neuritis is a common cause of acute painful monocular vision loss and may be the first presentation of multiple sclerosis or another...

At the Bedside

Classic presentation:
Young adult, often female.
Subacute monocular vision loss over hours to days.
Eye pain worse with movement.
Decreased color vision/red desaturation.
Relative afferent pupillary defect.
Fundus may be normal in retrobulbar neuritis; optic disc edema in papillitis.
Key exam:
Visual acuity and visual fields.
Pupils/RAPD.
Color vision, especially red desaturation.
Fundoscopy for disc edema, hemorrhages, retinal findings.
Neuro exam for MS, transverse myelitis, brainstem signs.
Dangerous mimics/red flags:
Age >50 or systemic symptoms → giant cell arteritis.
Sudden painless vision loss → CRAO/retinal detachment/vitreous hemorrhage.
Bilateral severe vision loss, longitudinal cord symptoms → NMOSD/MOGAD.
Fever, meningismus, orbital signs, proptosis → infection/orbital process.
Severe headache, neuro deficits → stroke/mass.
Progressive weeks/months → compressive lesion.
Workup:
MRI brain and orbits with gadolinium, fat-suppressed orbital sequences if available.
Consider MRI spine if myelitis symptoms.
ESR/CRP/platelets if age >50 or GCA concern.
Pregnancy test when relevant before imaging/meds.
Neurology and ophthalmology consultation, especially atypical cases.
Additional labs for atypical/recurrent/bilateral disease: AQP4-IgG, MOG-IgG, ANA/ACE/infectious testing as guided by specialists.
Management:
Typical optic neuritis: high-dose IV steroids can speed visual recovery but do not substantially change final visual outcome in classic cases.
Avoid low-dose oral prednisone alone — associated with higher recurrence in classic ONTT data.
Treat GCA immediately if suspected; do not wait for biopsy.
Plasma exchange may be needed for severe steroid-refractory demyelinating optic neuritis, especially NMOSD.
Disposition:
Admit or observation for severe vision loss, bilateral symptoms, atypical features, neurologic deficits, inability to obtain timely MRI/follow-up, or need for IV steroids.
Reliable mild typical cases may have urgent neuro-ophthalmology/neurology follow-up, but many ED pathways favor MRI and specialist evaluation.

A Classic Presentation

A 28-year-old woman presents with 2 days of right eye pain worse with movement and blurry vision. She reports colors look “washed out.” Exam shows VA 20/100 OD, red desaturation, and a right RAPD with normal fundus. MRI brain/orbits with gadolinium is ordered, neurology and ophthalmology are consulted, and she is treated with high-dose IV methylprednisolone due to functional vision loss and concern for demyelinating optic neuritis.

Study Directive

Practice distinguishing optic neuritis from CRAO, retinal detachment, vitreous hemorrhage, acute angle closure, and migraine aura.
Memorize the core exam triad: pain with EOM, red desaturation, RAPD.
Review MRI findings and MS risk counseling basics: brain white matter lesions increase future MS risk.
Write a one-page algorithm for painful monocular vision loss by anatomic location: cornea/anterior chamber/retina/optic nerve/brain.

Key Medications

Steroids for typical demyelinating optic neuritis when treating:
- Methylprednisolone 1 g IV daily x 3–5 days, commonly followed by oral taper per neurology/ophthalmology.
- Alternative historical regimen: methylprednisolone 250 mg IV q6h x 3 days.
Avoid: oral prednisone alone at approximately 1 mg/kg/day without IV lead-in for typical optic neuritis.
If GCA suspected with visual symptoms:
- Methylprednisolone 500–1000 mg IV daily x 3 days, then high-dose oral prednisone; consult ophthalmology/rheumatology.
Analgesia:
- Acetaminophen 650–1000 mg PO q6h PRN.
- NSAIDs if no contraindications, e.g., ibuprofen 400–600 mg PO q6h PRN.

High-Yield Pearls

Normal fundus does not exclude optic neuritis — “the patient sees nothing, and the doctor sees nothing” describes retrobulbar neuritis.
Pain with eye movement + red desaturation + RAPD is highly suggestive.
In patients >50 with visual symptoms, always consider giant cell arteritis and check ESR/CRP/platelets.

Board Question

A 30-year-old has painful monocular vision loss, red desaturation, RAPD, and normal fundoscopic exam. Which treatment approach is most appropriate if steroids are used?

ALow-dose oral prednisone alone
BTopical prednisolone drops only
CHigh-dose IV methylprednisolone
DImmediate intraocular pressure lowering with timolol

Reveal answer

Correct: C

Typical optic neuritis is treated, when treatment is chosen, with high-dose IV methylprednisolone to speed recovery. Low-dose oral prednisone alone is avoided because it has been associated with increased recurrence.

Recent Literature

Review or guideline Optic neuritis and autoimmune optic neuropathies: advances in diagnosis and treatment
Lancet Neurol, 2023 · cited 198×
Recent clinical Collaborative Latin American Imaging Network In Neuroimmunology Research (BRAIMS): Rationale, Structure, Challenges, and Future Directions
Mult Scler Relat Disord, 2026

4 of 4

Pacemakers

Pacemaker patients present with syncope, bradycardia, shock, palpitations, or chest pain, and the ECG may hide life-threatening malfunction or underlying...

At the Bedside

First questions:
Why was it placed? Pacemaker vs ICD vs CRT device?
Symptoms: syncope, presyncope, palpitations, shocks, dyspnea, chest pain, infection signs.
Recent generator change/lead revision? Trauma? New meds? Electrolyte/renal issues?
Initial ED assessment:
ABCs, monitor, IV access, defib pads.
12-lead ECG and rhythm strip.
Compare with prior ECG/device card if available.
CXR for lead position, fracture, dislodgement, pneumothorax after recent placement.
Labs: BMP/Mg/Ca, troponin if ischemic symptoms, CBC if infection, digoxin level if relevant, TSH if broad brady workup.
Interrogate device early via device representative/cardiology/electrophysiology.
Pacemaker code basics:
First letter chamber paced: A/V/D.
Second sensed: A/V/D.
Third response: I inhibited, T triggered, D dual.
Common: DDD paces/senses atrium and ventricle; can inhibit or trigger.
Malfunction patterns:
Failure to pace: no pacing spike when expected. Causes: battery depletion, oversensing, lead fracture, programming issue.
Failure to capture: pacing spike not followed by P wave/QRS. Causes: lead dislodgement, hyperkalemia, acidosis, ischemia, fibrosis, low output.
Failure to sense:
Undersensing: pacer spikes occur inappropriately despite intrinsic beats.
Oversensing: pacer mistakenly senses artifact/noise and withholds pacing.
Pacemaker-mediated tachycardia: reentrant loop in dual-chamber device; regular paced tachycardia near upper tracking rate.
Immediate unstable bradycardia management:
Follow ACLS: atropine may be attempted but may fail in pacer-dependent/infranodal disease.
Apply transcutaneous pacing pads early.
Sedate/analgesia if conscious, but do not delay pacing in extremis.
Treat reversible causes: hyperkalemia, ischemia, hypoxia, acidosis, hypothermia, medication toxicity.
Transvenous pacing if persistent instability or device failure.
Magnet use:
For most pacemakers, magnet converts to asynchronous pacing mode at a manufacturer-specific magnet rate.
Useful if oversensing inhibits pacing or sometimes to terminate pacemaker-mediated tachycardia.
In ICDs, magnet typically disables tachyarrhythmia shocks but does not change brady pacing.
Always monitor continuously; response varies by device/manufacturer/programming.
Pacemaker infection:
Pocket erythema, warmth, drainage, erosion, fever, bacteremia.
Needs blood cultures, IV antibiotics, cardiology/EP; definitive management often complete hardware removal.
Disposition:
Admit/telemetry for syncope, unstable rhythm, suspected malfunction, pacemaker dependence, device infection, lead dislodgement, battery depletion, significant electrolyte abnormality, or need for interrogation not completed.
Discharge only if asymptomatic, device interrogation reassuring, reversible issue addressed, and close EP follow-up.

A Classic Presentation

A 78-year-old with a permanent pacemaker presents after syncope. Monitor shows bradycardia at 30 with pacer spikes not followed by QRS complexes. He is hypotensive and confused. Pads are placed, transcutaneous pacing is started with analgesia as feasible, labs reveal potassium 7.1, and he receives IV calcium, insulin/dextrose, and albuterol while cardiology is called for device interrogation and possible transvenous pacing.

Study Directive

Draw four rhythm strips from memory: normal pacing, failure to pace, failure to capture, undersensing/oversensing.
Memorize the unstable bradycardia sequence: pads → atropine/pressors → TCP → transvenous pacing → treat reversible causes.
Review your hospital’s process for device interrogation: who to call, where magnets are stored, and how to identify manufacturer.
Practice interpreting pacemaker codes: VVI, DDD, AAI, CRT-D.

Mechanism Pearl of the Day: Today’s topics all hinge on compartment-level failure causing organ dysfunction: infection in the closed globe destroys vision in endophthalmitis, blood obstructs aqueous outflow in hyphema, inflammation blocks optic nerve conduction in optic neuritis, and electrical/mechanical capture failure prevents myocardial depolarization in pacemaker malfunction.

Key Medications

Unstable bradycardia temporizing meds:
- Atropine 1 mg IV q3–5 min, max 3 mg.
- Epinephrine infusion 2–10 mcg/min IV, titrate to response.
- Dopamine infusion 5–20 mcg/kg/min IV, titrate to response.
Sedation/analgesia for transcutaneous pacing if time allows:
- Fentanyl 25–50 mcg IV q5–10 min titrated.
- Midazolam 1–2 mg IV q2–5 min titrated.
- Ketamine analgesic/subdissociative 0.1–0.3 mg/kg IV may be considered; dissociative dosing 1–2 mg/kg IV if procedural sedation appropriate.
Hyperkalemia causing capture failure:
- Calcium gluconate 10% 3 g IV over 10 min, repeat as needed for ECG changes.
- Calcium chloride 10% 1 g IV preferably central line.
- Regular insulin 10 units IV + dextrose 25 g IV if glucose not elevated.
- Albuterol 10–20 mg nebulized.
- Sodium bicarbonate 50 mEq IV if severe acidosis/wide QRS as adjunct.
Device infection empiric antibiotics:
- Vancomycin 15–20 mg/kg IV initially, pharmacy-adjusted.
- Add gram-negative coverage such as cefepime 2 g IV q8h if septic, healthcare-associated, immunocompromised, or per local protocol.

High-Yield Pearls

Spike with no QRS = failure to capture; no spike when expected = failure to pace.
Hyperkalemia can cause pacemaker capture failure — always check potassium in pacemaker malfunction.
A magnet affects pacemakers and ICDs differently: pacemaker often asynchronous; ICD usually suspends shocks.

Board Question

A pacemaker-dependent patient is bradycardic and hypotensive. ECG shows pacer spikes that are not followed by QRS complexes. What is the malfunction?

AFailure to capture
BFailure to sense due to undersensing
CPacemaker-mediated tachycardia
DNormal DDD pacemaker function

Reveal answer

Correct: A

Failure to capture occurs when a pacer spike does not produce myocardial depolarization. Causes include lead dislodgement, battery/output problems, ischemia, acidosis, and hyperkalemia.

Recent Literature

Review or guideline Pacemakers
NEJM Evid, 2025
Recent clinical Cost-effectiveness of leadless versus transvenous single-chamber ventricular pacing: a propensity-weighted real-world study in France
Ann Med, 2026

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TheDaily Differential

Endophthalmitis

At the Bedside

Study Directive

Recent Literature

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