12-phase flow (12)

1. 1FRAME
   Frame acute vision loss as an EMERGENCY TRIAGE problem, not a leisurely differential. Two can-not-miss clocks dominate: CRAO = acute ischemic stroke (retina dies in ~90-100 min — Hayreh Ophthalmology 1980 PMID 6769079; Mac Grory Stroke 2021 PMID 33677974) and GCA = empiric high-dose steroid before biopsy to save the fellow eye (Maz ACR/VF 2021 PMID 34235884; Liu Ophthalmology 1994 PMID 7800356). Definitive pathway ownership is routed OUT by engine_id.
   advance: emergency-triage framing set; CRAO and GCA clocks foregrounded
2. 2ENTRY
   Capture the four triage binaries up front: painful vs painless, transient vs persistent, monocular vs binocular, ± other neuro deficits. These collapse the differential before any test (Biousse/Newman framework; Mac Grory Stroke 2021 PMID 33677974).
   inputs: pain_present, transient_vs_persistent, monocular_vs_binocular
   actions: workup.acute_vision_loss
   advance: all four triage binaries recorded
3. 3CONTEXT
   Risk substrate: age (≥50 → GCA prior up), the GCA symptom cluster (headache/jaw claudication/scalp tenderness/PMR), time since onset (retinal clock), vascular risk factors (CRAO/amaurosis = stroke-equivalent secondary-prevention urgency), demyelinating history, immunocompromise. This phase assigns the pretest priors.
   inputs: age, gca_symptom_cluster, time_since_onset, vascular_risk_factors, eye_pain_with_movement, demyelinating_or_nmosd_history, immunocompromise
   actions: workup.gca_temporal_arteritis
   advance: priors assigned by triage axes × age/vascular-risk; GCA cluster scored
4. 4RED_FLAGS
   Time-critical screen: (1) CRAO or amaurosis or any focal neuro deficit → activate stroke pathway, route to neuro.acute-stroke.core.v1 / neuro.tia.core.v1 (Mac Grory Stroke 2021 PMID 33677974); (2) age ≥50 + GCA cluster → empiric high-dose steroid NOW, do not wait for ESR/biopsy (Maz ACR/VF 2021 PMID 34235884); (3) post-op/post-injection painful eye → endophthalmitis route; (4) acute angle-closure → emergent IOP-lowering. Recognised and started here; ownership routed OUT.
   inputs: associated_neuro_deficits, recent_intraocular_surgery_or_injection
   actions: protocol.crao, protocol.stroke, workup.acute_stroke
   advance: CRAO/stroke, GCA, endophthalmitis, AACG red flags screened and time-critical action initiated
5. 5INITIAL_WORKUP
   Bedside afferent exam: visual acuity each eye, RAPD (the key localising sign), confrontation fields, dilated fundus (cherry-red spot vs pallid disc edema vs blood-and-thunder vs detachment vs vitreous blood — Hayreh & Zimmerman Retina 2007 PMID 17460582), IOP, colour vision. STAT ESR + CRP + platelets + CBC if any GCA suspicion (results never delay steroid). Urgent neuro-imaging (DWI-MRI) for binocular/cortical or CRAO (concurrent brain infarction common).
   inputs: rapd_relative_afferent_pupillary_defect, fundus_findings, intraocular_pressure, esr, crp, platelets
   actions: workup.acute_red_eye, panel.cbc, panel.inflammation, calc.nihss
   advance: afferent exam + fundus + IOP done; GCA inflammatory labs sent; imaging ordered if indicated
6. 6BRANCHING_WORKUP
   Branch by fundus + triage axes: cherry-red spot → CRAO (stroke pathway, GCA screen if ≥50); pallid disc edema + ≥50 + ↑ESR/CRP → arteritic AION (steroid emergency); hyperemic disc edema, <50, eye-movement pain, RAPD → optic neuritis (MRI brain/orbits, AQP4/MOG); blood-and-thunder → CRVO; macula-threatening detachment → RD (urgent vitreoretinal); dense vitreous blood → VH (B-scan); high IOP + closed angle → AACG; normal eye + homonymous field → occipital stroke (DWI-MRI). Temporal-artery biopsy / vascular imaging arranged but never gates steroid.
   inputs: fundus_findings, eye_pain_with_movement
   actions: workup.acute_stroke, workup.acute_headache, panel.cmp
   advance: syndrome localised; confirmatory test arranged; emergency therapy not delayed by it
7. 7DIFFERENTIAL
   Terminal differential with pivot findings: CRAO (cherry-red spot + sudden painless monocular loss + retinal clock pivot — STROKE) vs arteritic AION/GCA (≥50 + pallid disc edema + jaw claudication + ↑ESR/CRP/platelets pivot — STEROID) vs non-arteritic AION (small crowded "disc at risk", afebrile, normal ESR, vasculopath pivot) vs CRVO (blood-and-thunder fundus pivot) vs rhegmatogenous RD (curtain + flashes/floaters + Shafer sign pivot) vs vitreous hemorrhage (loss of red reflex + diabetic/PVD pivot) vs optic neuritis (young + pain on movement + dyschromatopsia + RAPD + normal/edematous disc pivot) vs acute angle-closure glaucoma (painful red eye + mid-dilated pupil + ↑IOP + haloes pivot) vs occipital/homonymous stroke (binocular congruous field cut + intact pupils + other neuro signs pivot) vs endophthalmitis (recent surgery/injection + hypopyon + pain pivot) vs functional vision loss (normal RAPD/fundus/OCT + non-physiologic fields + tunnel/spiral pivot — diagnosis of exclusion).
   advance: single best diagnosis selected; arteritic-vs-non-arteritic AION pivot explicitly resolved; co-existence (CRAO + GCA) flagged
8. 8RISK_STRATIFICATION
   Stratify by sight- AND life-threat. CRAO/amaurosis: stroke risk — NIHSS for any neuro deficit, ABCD2 for transient retinal/cortical ischemia, urgent vascular workup (Mac Grory Stroke 2021 PMID 33677974). GCA: threatened/established vision loss → IV pulse vs oral high-dose decision (Maz ACR/VF 2021 PMID 34235884). RD: macula-on (same-day surgical emergency) vs macula-off (more time-tolerant). Systemic-instability overlay (NEWS2/qSOFA) for endogenous endophthalmitis/sepsis or stroke with deterioration.
   inputs: associated_neuro_deficits, time_since_onset
   actions: calc.abcd2, calc.nihss, calc.news2, calc.qsofa
   advance: sight-threat tier + stroke/life-threat tier assigned
9. 9TREATMENT
   Emergency, etiology-stratified, ROUTE-OUT-after-stabilise: (1) GCA suspected → empiric high-dose corticosteroid IMMEDIATELY (oral prednisone ≥1 mg/kg, or IV methylprednisolone pulse if threatened/established vision loss) before biopsy, + aspirin, route to rheum.giant-cell-arteritis.core.v1 for taper/tocilizumab (Maz ACR/VF 2021 PMID 34235884; Liu Ophthalmology 1994 PMID 7800356). (2) CRAO → activate stroke pathway: ocular massage / IOP-lowering / anterior-chamber paracentesis are low-yield non-pharm temporising measures; IV thrombolysis within a tight window is the active stroke-pathway question (intra-arterial fibrinolysis NOT recommended — EAGLE Schumacher Ophthalmology 2010 PMID 20609991); route to neuro.acute-stroke.core.v1. (3) Optic neuritis → IV methylprednisolone speeds recovery; oral prednisone alone is contraindicated (↑recurrence) (Beck ONTT NEJM 1992/1993 PMIDs 1734247/8232485); route to neuro.optic-neuritis.core.v1. (4) AACG → emergent IOP-lowering (topical aqueous suppressants + acetazolamide ± osmotic), route to ophtho.acute-angle-closure-glaucoma.core.v1. (5) Endophthalmitis → emergent tap-and-inject route. Steroid/imaging pregnancy gating applied.
   inputs: pregnancy, gca_symptom_cluster, time_since_onset
   advance: etiology-specific emergency therapy started AND definitive ownership routed by engine_id
10. 10DISPOSITION
    CRAO / acute stroke / amaurosis → emergent ED + stroke unit (route to neuro.acute-stroke.core.v1 / neuro.tia.core.v1). GCA with vision loss → admit for IV pulse + urgent rheum/ophtho + biopsy ≤2 wk. Optic neuritis → admit/observation for IVMP + neurology. RD macula-on → same-day vitreoretinal surgery. Endophthalmitis → emergent ophthalmology. AACG → emergent ophthalmology after IOP control. Functional vision loss → reassurance + outpatient neuro-ophthalmology after organic causes excluded.
    inputs: associated_neuro_deficits
    advance: disposition + routed engine_id documented
11. 11MONITORING
    GCA: steroid response (headache/visual symptoms within 24-72 h), fellow-eye vigilance (untreated fellow-eye involvement risk is high — Liu Ophthalmology 1994 PMID 7800356), ESR/CRP trend. CRAO/stroke: neuro checks, completion of stroke secondary-prevention workup (carotid/cardiac/embolic). Optic neuritis: serial acuity/colour/fields — most recover acuity by 1 year even without steroid (Beck Arch Ophthalmol 1993 PMID 8512477). RD/endophthalmitis/AACG: per receiving engine.
    inputs: esr, crp
    actions: panel.inflammation
    advance: etiology-appropriate monitoring plan active or handed off to routed engine
12. 12FOLLOWUP
    CRAO/amaurosis: stroke/cardiology secondary prevention is the long-tail deliverable — antithrombotic, vascular-risk control, carotid intervention if indicated (Mac Grory Stroke 2021 PMID 33677974) via neuro.acute-stroke.core.v1 / neuro.tia.core.v1. GCA: long glucocorticoid taper + tocilizumab + relapse surveillance via rheum.giant-cell-arteritis.core.v1. Optic neuritis: MS/NMOSD/MOGAD demyelination workup + DMT via neuro.optic-neuritis.core.v1. Low-vision rehabilitation and counselling for irreversible loss; functional vision loss → supportive follow-up.
    inputs: vascular_risk_factors, demyelinating_or_nmosd_history
    advance: secondary-prevention / disease-specific follow-up handed to the routed engine_id