Cystoid Macular Edema

Cystoid macular edema (CME) is a pathological accumulation of fluid within the central retina (macula), forming characteristic cyst-like spaces in the outer plexiform layer (Henle fiber layer) and inner nuclear layer. The anatomical arrangement of radially oriented Henle fibers dictates that these cysts adopt a spoke-wheel or petaloid pattern around the fovea, the hallmark appearance on fluorescein angiography. CME is not a single disease but a common final pathway of numerous aetiologies including post-surgical inflammation, uveitis, diabetic macular disease, retinal vascular occlusion, drug toxicity, and inherited retinal dystrophies.

CME is the most common cause of visual loss following otherwise uncomplicated cataract surgery — a form known as Irvine-Gass syndrome, occurring in approximately 1–2% of clinical cases (though angiographic incidence is as high as 20%). In diabetic patients, CME is a significant component of diabetic macular edema (DME), the leading cause of vision loss in working-age adults globally. Across all causes, the fundamental mechanism involves breakdown of the blood-retinal barrier with accumulation of protein-rich fluid within the retinal parenchyma.

Modern management is aetiology-directed and has been transformed by intravitreal anti-VEGF therapy, slow-release corticosteroid implants, and improved surgical techniques. Optical coherence tomography (OCT) has become the diagnostic gold standard, providing high-resolution cross-sectional imaging of retinal fluid, layer-by-layer morphology, and quantitative central subfield thickness (CST) measurements for treatment monitoring.

CME is a manifestation of diverse underlying pathologies that share the final common pathway of blood-retinal barrier disruption:

Post-Surgical (Irvine-Gass Syndrome)

The most common cause overall. CME follows cataract extraction (phacoemulsification), pars plana vitrectomy, trabeculectomy, retinal laser, and other intraocular procedures. Surgical trauma triggers prostaglandin release from the iris and ciliary body, disrupting the inner blood-retinal barrier. Vitreous incarceration at the cataract wound, retained lens fragments, and iris tuck are compounding risk factors. Clinical CME occurs in approximately 1–2% of routine phacoemulsification; complicated surgery increases risk substantially.

Uveitic CME

Intraocular inflammation from any cause — intermediate, posterior, or panuveitis — disrupts the blood-retinal barrier through inflammatory cytokines (IL-6, TNF-α, VEGF) and leukostasis. CME is the primary cause of vision loss in uveitis, affecting up to 30% of patients with chronic uveitis. Associated conditions include sarcoidosis, Behçet's disease, juvenile idiopathic arthritis (JIA)-associated uveitis, pars planitis, and birdshot chorioretinopathy.

Diabetic Macular Edema (DME)

DME is the most common cause of CME globally by prevalence. VEGF-driven inner blood-retinal barrier breakdown from pericyte loss, basement membrane thickening, and oxidative stress leads to macular fluid accumulation. CME occurs in both the cystoid (focal/multifocal hard exudate) and diffuse (generalised macular thickening) subtypes.

Retinal Vascular Occlusion

Both BRVO and CRVO cause CME through ischaemia-induced VEGF upregulation and hydrostatic pressure elevation. CME in vein occlusion is typically more severe and persistent than post-surgical CME, requiring multiple anti-VEGF injections or sustained-release steroid implants.

Drug-Induced CME

• Topical prostaglandin analogues (latanoprost, bimatoprost, travoprost): disrupt the blood-aqueous barrier with secondary effects on the posterior segment; a recognised class-effect for CME
• Niacin (nicotinic acid): dose-dependent CME, thought to involve a direct Müller cell effect via prostaglandin-independent pathways; generally reversible on cessation
• Taxanes (paclitaxel, docetaxel): chemotherapy-induced CME, mechanism unclear
• Fingolimod (sphingosine-1-phosphate receptor modulator) for multiple sclerosis: direct CME risk; black box warning; typically bilateral
• Topical epinephrine / dipivefrin: historical; caused aphakic CME

Inherited Retinal Dystrophies

• Retinitis pigmentosa (RP): CME occurs in 10–50% of RP patients; mechanism involves Müller cell dysfunction and carbonic anhydrase deficiency; responds to systemic acetazolamide
• X-linked retinoschisis: foveal schisis from RS1 gene mutations disrupts Müller cell function
• Best vitelliform macular dystrophy (BVMD): CME component may respond to acetazolamide

Other Causes

• Epiretinal membrane (ERM) with vitreomacular traction
• Radiation retinopathy
• Macular telangiectasia type 1 (MacTel 1)
• Choroidal neovascularisation (exudative AMD)
• Idiopathic (rare; diagnosis of exclusion)

1. Blood-Retinal Barrier Breakdown

The retina is protected by two barriers: the inner blood-retinal barrier (iBRB) — formed by tight junctions (zonula occludens) between retinal capillary endothelial cells — and the outer blood-retinal barrier (oBRB) — formed by RPE tight junctions. CME arises primarily from iBRB disruption, though oBRB disruption can contribute (e.g., in inflammatory or diabetic disease). Loss of tight junction integrity allows plasma and protein-rich fluid to leak from retinal capillaries into the retinal parenchyma.

2. Prostaglandin and Inflammatory Cascade

In post-surgical CME, surgical trauma triggers arachidonic acid release from cell membranes, generating prostaglandins (PGE2, PGI2) via cyclooxygenase (COX-1 and COX-2) enzymes. Prostaglandins disrupt endothelial tight junctions by phosphorylating VE-cadherin and increasing intracellular cAMP. This is the rationale for NSAID prophylaxis and treatment in pseudophakic CME.

3. VEGF-Mediated Permeability

Vascular endothelial growth factor (VEGF) — particularly VEGF-A — is the dominant driver of vascular permeability in diabetic CME and vein occlusion-related CME. VEGF activates VEGFR-2 on endothelial cells, triggering phosphorylation of VE-cadherin, opening of intercellular junctions, and increased paracellular permeability. Hypoxia-inducible factor-1α (HIF-1α) drives VEGF transcription in ischaemic retina. The VEGF pathway is also activated by pro-inflammatory cytokines (IL-6, TNF-α), creating an inflammatory-angiogenic cycle.

4. Fluid Accumulation in the Henle Fiber Layer

The outer plexiform layer (OPL) of the macula is occupied by the obliquely oriented axons of photoreceptors — the Henle fiber layer. This unique radial arrangement creates natural anatomical channels oriented around the fovea. When fluid leaks from capillaries in the inner nuclear layer or OPL, it tracks along these fibers in a spoke-wheel distribution, producing the characteristic petaloid pattern on fluorescein angiography.

5. Müller Cell Dysfunction

Müller cells are the primary glia of the retina and play a critical role in fluid homeostasis through expression of aquaporin-4 (AQP4) water channels and Kir4.1 potassium channels at their endfeet. In diabetic and inflammatory CME, Müller cell dysfunction and downregulation of these channels impairs the normal active resorption of retinal fluid, allowing cystoid spaces to persist and enlarge. In RP-associated CME, Müller cell failure may be a direct consequence of photoreceptor degeneration.

6. Photoreceptor Damage and Chronicity

Persistent fluid disrupts the physical and metabolic relationship between photoreceptors and the RPE, impairing phototransduction, visual cycle retinoid transport, and photoreceptor outer segment phagocytosis. Chronic cystoid spaces cause progressive thinning of the outer nuclear layer, fragmentation of the ellipsoid zone (IS/OS junction), and ultimately irreversible photoreceptor loss — the basis of the guarded prognosis in chronic CME.

Surgical Risk Factors

• Cataract surgery (phacoemulsification) — particularly complicated cases with posterior capsule rupture, vitreous loss, or iris trauma
• Retained lens material post-cataract surgery
• Anterior vitrectomy with vitreous incarceration at the wound
• Multiple prior intraocular procedures
• Pars plana vitrectomy, trabeculectomy, retinal laser treatment

Ocular Risk Factors

• Pre-existing uveitis or intraocular inflammation
• Diabetic retinopathy (especially proliferative stage)
• Retinal vein occlusion (BRVO or CRVO)
• Epiretinal membrane with vitreomacular traction
• Prior episode of CME (strong predictor of recurrence)
• Retinitis pigmentosa and other inherited retinal dystrophies
• Pseudoexfoliation syndrome (higher inflammation risk with surgery)
• Use of topical prostaglandin analogue glaucoma drops

Systemic Risk Factors

• Diabetes mellitus — especially poor glycaemic control (high HbA1c)
• Systemic hypertension — worsens vascular permeability
• Systemic inflammatory conditions (sarcoidosis, Behçet's, JIA, ankylosing spondylitis)
• Multiple sclerosis treated with fingolimod
• Dyslipidaemia treated with niacin
• Chemotherapy with taxane agents

Clinical Signs on Examination

• Reduced best-corrected visual acuity (BCVA): typically 6/12 to 6/60; may be worse in severe or chronic CME
• Loss of foveal reflex: the normal bright foveal light reflex is absent; replaced by a dull, waxy or slightly grey appearance; subtle in early disease
• Macular thickening: the foveal region appears slightly elevated or has a honeycomb appearance with loss of the central depression; may be detectable with a fundus contact lens at the slit lamp
• Hard exudates: circinate or stellate (star pattern) arrangement around the fovea in chronic or diabetic CME, representing extravasated lipid from leaking microaneurysms or telangiectatic vessels
• Intraretinal microvascular abnormalities (IRMA): in diabetic CME
• Vitreous cells / anterior vitreous flare: in uveitic CME; indicates active inflammation
• Watzke-Allen test: narrow slit beam projected on the macula — interrupted or thinned beam suggests macular pathology (positive in significant CME or macular hole)
• Amsler grid: metamorphopsia (line distortion) or central scotoma

Fundus Camera and Imaging Signs

• OCT (primary diagnostic tool): intraretinal cystoid fluid spaces (dark hyporeflective lacunae) in the INL and OPL; loss of normal foveal contour; increased CST; subretinal fluid if present; ERM or VMT if applicable; integrity of ellipsoid zone (key prognostic marker)
• Fluorescein angiography (FFA): classic petaloid hyperfluorescence in the late phase — leakage from perifoveal capillaries tracks along Henle fibers in a flower-petal pattern centred on the fovea; early frames show capillary leakage without the full petaloid pattern
• Optic disc leakage: concurrent disc hyperfluorescence on FFA may be seen in post-surgical or inflammatory CME
• OCT-angiography (OCTA): identifies foveal avascular zone (FAZ) enlargement, deep capillary plexus dropout, and microaneurysms without dye injection

Symptoms arise from disruption of the normal photoreceptor architecture in the macula — the region responsible for central, high-acuity, colour, and detailed vision. Severity correlates broadly with the degree of macular thickening, foveal involvement, and chronicity.

Common Presenting Symptoms

• Reduced central visual acuity: blurring of central vision, typically gradual in onset; acute reduction in VA post-cataract surgery is the classic presentation of pseudophakic CME; patients may notice difficulty reading fine print
• Metamorphopsia: distortion of straight lines and shapes; a sensitive symptom of macular involvement; detectable with Amsler grid self-monitoring
• Central scotoma: a central or paracentral blind spot; particularly in severe or chronic CME with foveal photoreceptor compromise
• Micropsia: objects appear smaller than normal; results from increased separation of photoreceptors by cystoid fluid spaces
• Reduced colour saturation: colours appear washed out or less vivid; a subtle but consistent finding in macular disease
• Difficulty with contrast sensitivity: trouble with low-contrast tasks (reading in dim light, driving at dusk) even when Snellen acuity is relatively preserved

Symptom Patterns by Aetiology

• Post-surgical CME: initially excellent post-operative vision (first few weeks) followed by gradual blurring starting 4–12 weeks after cataract surgery
• Uveitic CME: visual blurring accompanied by photophobia, floaters, or ocular pain from underlying inflammation
• Diabetic CME: gradual onset, often bilateral; patients may underreport symptoms due to gradual adaptation
• Drug-induced CME: typically mild; reduced vision while on offending medication; may resolve within weeks of drug cessation

• Photoreceptor loss (outer nuclear layer thinning): the most clinically significant complication; chronic cystoid fluid disrupts the photoreceptor-RPE metabolic axis, causing irreversible photoreceptor atrophy and permanent central vision loss
• Ellipsoid zone (IS/OS) disruption: fragmentation of the IS/OS band on OCT is a reliable biomarker of photoreceptor structural damage and is strongly associated with poor visual recovery even after fluid resolution
• Lamellar macular hole: chronic CME creates tissue-deficient cysts that may collapse, forming a partial-thickness (lamellar) defect in the macula; may progress to full-thickness macular hole
• Full-thickness macular hole (FTMH): rare but serious; occurs when large cystoid spaces coalesce and the foveal tissue ruptures; requires vitrectomy with ILM peeling
• Epiretinal membrane (ERM) formation: chronic inflammation or surgery stimulates glial and RPE cell migration to the inner retinal surface; ERM causes tractional CME and may perpetuate the cycle of fluid accumulation
• RPE degeneration: in chronic CME, prolonged fluid contact damages the RPE; focal RPE atrophy leads to geographic scotoma
• Chronic uveitis complications: posterior synechiae, cataract, hypotony, band keratopathy — in uveitic CME with poorly controlled inflammation
• Steroid-related complications: intravitreal or periocular steroid treatment for CME carries risks of steroid-induced ocular hypertension and posterior subcapsular cataract

CME is frequently a manifestation or complication of systemic disease. Identifying and managing the systemic cause is essential for effective CME treatment.

Diabetes Mellitus

Diabetic macular edema (DME), of which CME is a key component, is the leading cause of vision loss in working-age adults in developed countries. Systemic risk factors for DME severity include poor glycaemic control (HbA1c >7%), hypertension, dyslipidaemia, nephropathy, anaemia, and pregnancy. Systemic treatment optimisation — tight glycaemic control, antihypertensive therapy, lipid-lowering agents — reduces the incidence and severity of DME and enhances the response to ocular treatment. The UKPDS, ACCORD-Eye, and DCCT/EDIC trials established the retinal benefits of systemic risk factor control.

Autoimmune and Inflammatory Conditions

• Sarcoidosis: granulomatous uveitis causing bilateral chronic CME; may require systemic methotrexate or mycophenolate; serum ACE, chest CT, and biopsy for diagnosis
• Behçet's disease: occlusive vasculitis causing severe CME and disc oedema; colchicine, azathioprine, infliximab used
• Juvenile idiopathic arthritis (JIA): uveitis-associated CME in children; methotrexate and adalimumab are disease-modifying agents
• Ankylosing spondylitis, psoriatic arthritis: HLA-B27-associated anterior uveitis can cause secondary CME
• Birdshot chorioretinopathy: HLA-A29 associated; posterior uveitis with bilateral chronic CME

Hypertension

Systemic hypertension is a major risk factor for retinal vein occlusion (BRVO and CRVO), a leading cause of vascular CME. Adequate blood pressure control is a preventive measure and improves long-term vascular outcomes. Hypertension also worsens diabetic maculopathy.

Multiple Sclerosis (Fingolimod)

Fingolimod (Gilenya), a sphingosine-1-phosphate receptor modulator used for relapsing-remitting MS, causes CME in approximately 0.4–0.6% of treated patients. The mechanism involves sphingosine-1-phosphate receptor modulation on Müller cells and vascular endothelium. CME typically occurs within 3–6 months of initiation, is often bilateral, and resolves with drug cessation. Baseline and follow-up OCT monitoring is mandated in guidelines for all fingolimod-treated patients.

Dyslipidaemia (Niacin Therapy)

Nicotinic acid (niacin) used for dyslipidaemia causes a distinctive CME that is bilateral, dose-dependent, and generally reversible on drug cessation. It occurs in up to 0.7–2% of patients on high-dose niacin (≥1.5 g/day). The mechanism is prostaglandin-independent and may involve a direct Müller cell channel effect. FFA typically shows minimal leakage despite prominent cysts on OCT — a pattern sometimes called “pseudocystoid” because of the lack of true vascular leakage.

Retinitis Pigmentosa (Inherited)

CME in RP is thought to arise from Müller cell dysfunction secondary to progressive photoreceptor degeneration, with loss of carbonic anhydrase activity impairing fluid reabsorption. It occurs in 10–50% of RP patients and may be bilateral. Unlike other forms, it responds preferentially to oral carbonic anhydrase inhibitors (acetazolamide 250–500 mg/day) or topical CAIs (dorzolamide, brinzolamide) rather than anti-VEGF agents.

Diagnosis combines clinical history, risk factor identification, visual function testing, and multimodal imaging. OCT is the cornerstone of diagnosis, quantification, and treatment monitoring.

History and Risk Factor Review

• Recent intraocular surgery (type, complications, timing relative to visual symptoms)
• History of diabetes, uveitis, retinal vein occlusion, RP, or other ocular conditions
• Current medications: prostaglandin analogue drops, niacin, fingolimod, taxanes
• Timing and rate of visual decline — acute post-surgical vs. gradual diabetic progression

Visual Function Testing

• BCVA (best-corrected visual acuity): primary functional endpoint for treatment decisions and monitoring
• Contrast sensitivity: may be disproportionately reduced relative to Snellen acuity in early CME
• Amsler grid: patient self-monitoring for metamorphopsia and central scotoma
• Colour vision (Ishihara / D-15): subtle acquired dyschromatopsia in macular disease
• Microperimetry: functional assessment of macular sensitivity; maps scotoma and fixation stability; useful for monitoring chronic CME

OCT (Primary Diagnostic and Monitoring Tool)

• Spectral-domain OCT (SD-OCT): standard of care; provides 5–7 μm axial resolution cross-sections; quantifies CST (central subfield thickness), detects cystoid spaces, identifies subretinal fluid, evaluates EZ integrity
• Swept-source OCT: longer wavelength (1050 nm); better choroidal and posterior pole penetration; useful for complex cases
• OCT-angiography (OCTA): non-invasive angiography; detects FAZ (foveal avascular zone) size, deep capillary plexus non-perfusion, microaneurysms, and neovascularisation without fluorescein injection
• Key OCT findings in CME: hyporeflective cystoid spaces in INL/OPL; loss of foveal contour; disruption or loss of ellipsoid zone and external limiting membrane; increased CST; ERM or VMT if present; subretinal fluid in some cases

Fluorescein Angiography (FFA)

• Demonstrates the classic petaloid leakage pattern in late-phase frames (10–15 minutes post-injection)
• Identifies concurrent disc oedema, retinal capillary non-perfusion, microaneurysms, and neovascularisation
• Less necessary for diagnosis when OCT is available; valuable for mapping ischaemia, planning laser treatment in DME or BRVO, and identifying subtle angiographic leakage not visible on OCT
• Note: niacin-associated CME shows minimal FFA leakage despite prominent cysts (pseudocystoid pattern)

Additional Investigations

• Blood tests: fasting glucose, HbA1c (diabetes), FBC (anaemia), ESR/CRP (inflammation), ACE and VDRL (sarcoidosis, syphilis), ANA (JIA), blood pressure
• Electroretinography (ERG): pattern ERG or mfERG to assess macular function in inherited retinal disorders; full-field ERG for RP
• B-scan ultrasonography: if media opacity obscures fundal view
• Imaging: chest X-ray or CT for sarcoidosis; MRI for MS in fingolimod-related CME

Management is aetiology-directed, with treatment addressing both the underlying cause and the retinal fluid directly. Early treatment — before ellipsoid zone disruption — offers the best chance of visual recovery.

1. Post-Surgical CME (Irvine-Gass)

• Topical NSAIDs (ketorolac, nepafenac, diclofenac, bromfenac): inhibit COX-1 and COX-2, reducing prostaglandin synthesis; first-line; used 4–6 times daily; highly effective in acute post-surgical CME and as prophylaxis in high-risk patients
• Topical corticosteroids (prednisolone acetate 1%, dexamethasone): adjunct to NSAIDs; address the broader inflammatory cascade
• Combination NSAID + steroid drops: more effective than either agent alone; sustained use for 3–6 months often required
• Periocular / intravitreal corticosteroids: sub-Tenon triamcinolone acetonide or intravitreal triamcinolone for refractory pseudophakic CME not responding to topical treatment
• Nd:YAG vitreolysis / surgical vitrectomy: if vitreous incarceration at the cataract wound is identified as the cause; surgical release of traction resolves CME

2. Uveitic CME

• Treat the underlying uveitis: topical, periocular, or systemic corticosteroids; systemic immunosuppression (methotrexate, mycophenolate, azathioprine, adalimumab) for chronic or recurrent disease
• Intravitreal triamcinolone or sustained-release dexamethasone implant (Ozurdex) for persistent uveitic CME; fluocinolone acetonide implant (Yutiq/Iluvien) for chronic cases
• Monitor for steroid-related IOP rise and posterior subcapsular cataract with any intravitreal or periocular steroid use

3. Diabetic CME (Centre-Involving DME)

• Intravitreal anti-VEGF therapy (first-line): ranibizumab (Lucentis), aflibercept (Eylea), bevacizumab (Avastin — off-label), faricimab (Vabysmo — dual anti-VEGF/Ang-2); monthly injection series followed by treat-and-extend protocol; the RISE/RIDE, RESTORE, VISTA/VIVID, and PROTOCOL T trials established anti-VEGF superiority for centre-involving DME
• Intravitreal corticosteroids: dexamethasone implant (Ozurdex) or fluocinolone acetonide implant (Iluvien/Yutiq) for pseudophakic patients or anti-VEGF non-responders; risk of IOP elevation and cataract
• Focal/grid laser photocoagulation: now second-line; reduces risk of moderate vision loss but does not improve VA as effectively as anti-VEGF; useful adjunct for hard exudates and non-central DME
• Systemic optimisation: glycaemic control (target HbA1c <7%), antihypertensive therapy, lipid control (statins, fenofibrate — ACCORD-Lipid data)

4. Vascular CME (BRVO / CRVO)

• Intravitreal anti-VEGF: ranibizumab (BRAVO/CRUISE trials), aflibercept (VIBRANT/COPERNICUS/GALILEO), bevacizumab; first-line for macular oedema in both BRVO and CRVO
• Dexamethasone intravitreal implant (Ozurdex): effective in both BRVO and CRVO (GENEVA trial); particularly useful in pseudophakic patients; duration 3–6 months per implant
• Grid laser (BRVO): second-line; reduces recurrence rate; not effective in CRVO

5. Drug-Induced CME

• Prostaglandin analogue glaucoma drops: switch to a non-PGA IOP-lowering agent (beta-blocker, alpha-agonist, CAI); CME typically resolves within weeks to months; topical NSAIDs may accelerate resolution
• Niacin: reduce dose or discontinue; CME resolves spontaneously in most cases; topical NSAIDs have limited effect (not prostaglandin-driven)
• Fingolimod: discontinue drug in consultation with the treating neurologist; CME usually resolves within weeks; topical NSAIDs may assist

6. RP-Associated CME

• Oral acetazolamide (250–500 mg/day): first-line; inhibits carbonic anhydrase in RPE and Müller cells, enhancing fluid resorption; effective in approximately 50–70% of RP-CME cases; monitor for systemic side effects (paraesthesia, renal stones, metabolic acidosis)
• Topical carbonic anhydrase inhibitors (dorzolamide, brinzolamide): less effective but better tolerated; useful if systemic acetazolamide is not tolerated
• Anti-VEGF: limited evidence; may help in a subset

7. Surgical Management

• Pars plana vitrectomy (PPV): indicated for CME associated with vitreomacular traction, epiretinal membrane, or incarcerated vitreous at the cataract wound; ILM peeling may be performed to release tractional forces
• Macular hole repair: PPV with ILM peeling and gas tamponade if chronic CME progresses to full-thickness macular hole

Visual prognosis depends primarily on aetiology, duration of CME, and the structural integrity of the ellipsoid zone (IS/OS layer) on OCT at the time of diagnosis and treatment.

By Aetiology

• Post-surgical CME: generally excellent; most cases resolve within 3–6 months of topical NSAID and/or steroid treatment with full visual recovery; chronic pseudophakic CME (>6 months) carries a more guarded prognosis, particularly if ellipsoid zone is disrupted
• Uveitic CME: guarded to moderate; recurrence is common with inflammatory flares; prognosis depends on the underlying inflammatory condition and adequacy of long-term immunosuppression
• Diabetic CME: variable; anti-VEGF treatment achieves mean VA gains of 7–12 letters (ETDRS) in clinical trials; patients with baseline VA ≥6/12 and preserved EZ fare better; incomplete responders to anti-VEGF may benefit from steroid implants; long-term prognosis limited by progressive diabetic retinopathy and ischaemia
• Vascular CME (BRVO): better than CRVO; many BRVO patients achieve 6/12 or better with anti-VEGF treatment
• Vascular CME (CRVO): more guarded; visual outcomes limited by macular ischaemia; anti-VEGF reduces fluid but VA gain is variable
• Drug-induced CME: generally excellent after drug cessation; vision usually returns to baseline
• RP-associated CME: moderate; acetazolamide reduces fluid but underlying photoreceptor degeneration limits long-term visual outcome

Key Prognostic OCT Biomarkers

• Ellipsoid zone (EZ) integrity: the most robust predictor of visual recovery; intact EZ correlates with better VA outcomes after fluid resolution; disrupted or absent EZ indicates photoreceptor loss and poor prognosis
• External limiting membrane (ELM) integrity: ELM disruption parallels photoreceptor inner segment loss; independently predictive of VA outcome
• Central subfield thickness (CST): correlates imperfectly with VA; thickness reduction does not always translate to VA improvement; structural biomarkers outperform CST for prognosis
• Disorganisation of retinal inner layers (DRIL): loss of defined boundaries between GCL, IPL, and INL; a functional biomarker associated with poor VA in DME
• Subretinal fluid (SRF): in some contexts (e.g., neovascular AMD), mild SRF may be associated with better outcomes than pure IRF; in DME, SRF tends to respond well to anti-VEGF

Long-Term Monitoring

CME in chronic conditions (uveitis, diabetes, RP, retinal vein occlusion) requires lifelong monitoring. OCT monitoring intervals are typically 4–8 weeks during active treatment and 3–6 months in stable treated patients. Recurrence is common and early detection allows prompt retreatment to minimise cumulative photoreceptor damage.