10 Management-Changing Clinical Scenarios

Clinical Scenarios: En Face OCT in Practice

Pattern recognition is built case by case. This module works through five scenarios where en face imaging changed the diagnosis, the management decision, or both — not by being clever, but by revealing information that B-scan alone could not provide. For each case, consider the B-scan finding before seeing the en face result.

Case: Subtle ERM Detection

Clinical context: A 58-year-old woman with 2 months of mild metamorphopsia in the right eye. Distance VA 20/25. Amsler grid shows mild central distortion. Dilated exam: foveal reflex slightly dull; no obvious membrane visible.

B-scan finding: Standard foveal B-scan shows a mildly elevated central retinal thickness (CRT 340 μm). A thin, barely visible hyper-reflective line is present on the ILM surface at the fovea. The EZ band appears continuous. No fluid.

En face finding: ILM slab en face shows fine parallel striae in the temporal parafoveal region extending to the foveal margin. The striae are subtle but unambiguous — they converge slightly at a central point, consistent with stage 2 ERM with focal traction. The spatial extent of the membrane covers approximately 60% of the macular area.

• Management change: B-scan alone suggested "mild ERM, monitor." En face clarified: the membrane is large and has traction component. Referred for vitreoretinal surgical consultation with full en face imaging documentation.
• Teaching point: ERM extent on B-scan (single-line raster) consistently underestimates true spatial coverage. Always obtain ILM en face when ERM is present before counseling patients or setting monitoring intervals.
• Serial monitoring: En face provides the most sensitive longitudinal marker — progressive striae density or new focal pucker indicates advancing stage before B-scan thickness changes cross clinical thresholds.

Case: Early AMD Monitoring

Clinical context: A 71-year-old man with known intermediate AMD (large soft drusen, no fluid) being followed annually. Last visit OCT appeared stable. No new symptoms.

B-scan finding: Standard 5-line raster B-scan shows multiple medium and large drusen (largest ~180 μm) with mild RPE irregularity. The EZ band appears intact across all scan lines. Impression: stable intermediate AMD.

En face finding: RPE slab en face reveals a dense drusen distribution across the entire 6×6 mm scan area — extending well beyond the central 3 mm captured by the 5-line raster. A new, subtle dark zone of ~0.5 mm² is visible superior to the foveal center, corresponding to nascent RPE atrophy not visible on any of the B-scan lines.

• Management change: The nascent atrophy identified on en face prompted transition from annual to 6-month monitoring intervals and initiation of AREDS2 supplementation discussion.
• Teaching point: Drusen burden assessed by foveal B-scan lines alone underestimates geographic extent in the majority of intermediate AMD patients. RPE slab en face provides a complete spatial map.
• Staging impact: En face-based drusen area quantification directly affects AREDS2 eligibility assessment and trial enrollment criteria — point-counting from B-scan lines is no longer adequate for staging in evidence-based practice.

Case: DME Treatment Response

Clinical context: A 64-year-old woman with type 2 diabetes and DME being treated with intravitreal ranibizumab, 3 loading doses completed. VA has improved from 20/60 to 20/40. Clinician is deciding whether to continue monthly vs. extend the interval.

B-scan finding: CRT has decreased from 520 μm to 390 μm. Some residual intraretinal hypo-reflective spaces remain at the fovea, but their distribution is difficult to assess on standard line scans.

En face finding: Inner retinal slab en face shows a pronounced petalloid cystoid pattern (6-petal arrangement) at baseline. Post-treatment en face shows marked reduction in the spatial extent of the cystoid pattern — central petals have resolved, but two parafoveal cysts persist in the nasal sector. The EZ slab shows a focal area of disruption nasally corresponding to the persistent cysts.

• Management change: The persistent nasal cysts on en face, invisible on the standard foveal B-scan line, prompted 2 additional monthly doses before extending. At next visit, nasal cysts had resolved on en face.
• Teaching point: DME has a three-dimensional distribution. Central foveal B-scan captures only one axis. En face inner retinal slab assessment before declaring "dry" prevents premature interval extension and recurrence.
• EZ correlation: EZ slab disruption on en face correlates with photoreceptor integrity loss — this provides prognostic information for final VA even before fluid fully resolves.

Case: CNV Activity Assessment

Clinical context: A 78-year-old man with known wet AMD, type 1 CNV, on PRN anti-VEGF. Last injection 10 weeks ago. VA stable at 20/40. Patient denies symptoms. Clinician is deciding whether to inject or monitor.

B-scan finding: CRT 298 μm, within normal limits. A shallow fibrovascular PED persists at the fovea, unchanged from prior visit. No obvious sub-retinal or intra-retinal fluid on standard B-scan lines.

En face finding: RPE slab en face shows a subtle new area of heterogeneity at the superior margin of the known PED — slightly brighter, irregular texture suggesting new membrane growth. OCTA en face at the outer retinal level shows a small new flow loop at this location, not present on the prior visit OCTA. No SRF is detectable on en face yet.

• Management change: The new OCTA flow loop identified on en face — before any detectable fluid — prompted an injection at this visit rather than continuing observation. At 4-week follow-up, OCTA confirmed flow loop regression without fluid development.
• Teaching point: CNV activity on OCTA en face precedes fluid accumulation. In PRN treatment protocols, OCTA can detect reactivation earlier than B-scan fluid monitoring — potentially allowing treatment before visual acuity decline occurs.
• Limitations: OCTA flow sensitivity has limits; small lesions (<0.2 mm²) may be below detection threshold. Projection artifacts from RPE elevation can mimic CNV flow. Always correlate structural and flow en face views.

Case: Vitreomacular Interface

Clinical context: A 66-year-old man with 3 months of progressive metamorphopsia and mildly decreased VA (20/30). Fundus exam shows no obvious pathology at the fovea. Clinician suspects early ERM but the standard B-scan is equivocal.

B-scan finding: The standard foveal B-scan shows a slightly elevated CRT (315 μm) with a subtle hyper-reflective line on the ILM surface. The foveal pit contour appears mildly blunted. The B-scan is categorized as "possible early ERM vs. vitreomacular adhesion — monitor."

En face finding: ILM slab en face shows a distinctive star-burst pattern of radial folds converging on a 400 μm zone 250 μm nasal to the foveal center — the hallmark of focal vitreomacular traction (VMT). The VMT footprint is clearly delineated. No broad ERM striae are present.

• Management change: The en face VMT pattern changed the diagnosis from "possible ERM" to confirmed VMT. VMT under 1500 μm footprint has a higher spontaneous release rate — patient was counseled on watchful waiting vs. ocriplasmin, and opted for 3-month serial monitoring. VMT spontaneously released at 3 months.
• Teaching point: ERM and VMT have distinct en face patterns. ERM = parallel striae (tangential contraction). VMT = radial folds converging on a central point (focal traction). This distinction cannot always be made from B-scan alone and directly affects surgical vs. pharmacological treatment decisions.
• Documentation: Document VMT footprint size and location on en face at each visit — increasing footprint size or change from eccentric to foveal involvement signals the need to escalate management.