Central Serous Retinopathy

Central serous chorioretinopathy (CSCR), also termed central serous retinopathy (CSR), is a condition characterised by serous detachment of the neurosensory retina at the macula, caused by focal dysfunction or disruption of the retinal pigment epithelium (RPE) with subsequent accumulation of protein-rich fluid in the subretinal space. It is one of the most common retinal conditions encountered in clinical practice, ranking fourth in frequency among visually significant macular diseases after age-related macular degeneration, diabetic retinopathy, and branch retinal vein occlusion.

CSCR predominantly affects young to middle-aged males, with a characteristic association with psychological stress, Type A personality, and exogenous or endogenous corticosteroid exposure. The underlying structural substrate is pachychoroid — pathological dilatation of the outer choroidal vessels (Haller layer) with consequent congestion, hyperperfusion, and increased hydrostatic pressure transmitted to the RPE. Most acute episodes are self-limiting, resolving spontaneously within 3–4 months with restoration of good central vision. However, chronic CSCR (persisting beyond 3–4 months or recurring) can lead to permanent RPE atrophy, photoreceptor loss, and irreversible visual impairment.

Optical coherence tomography (OCT) has transformed the diagnosis and monitoring of CSCR, enabling non-invasive quantification of subretinal fluid and choroidal thickness. Half-dose photodynamic therapy (PDT) with verteporfin has emerged as the most effective treatment for chronic CSCR, targeting the underlying choroidal hyperpermeability rather than the RPE leak point directly.

CSCR is considered part of the pachychoroid disease spectrum — a group of conditions sharing the common anatomical substrate of dilated outer choroidal vessels. The condition is idiopathic in the majority of cases, with no single causative agent identified, but several factors consistently predispose to or precipitate the disease.

Pachychoroid

The fundamental anatomical predisposition is pachychoroid — dilatation and engorgement of the outer choroidal vessels (Haller layer, Sattler layer) with attenuation of the overlying choriocapillaris. This leads to increased choroidal hydrostatic pressure, venous congestion, and focal ischaemia or hyperperfusion of the choriocapillaris. The resulting stress on the overlying RPE creates focal areas of RPE dysfunction that serve as the leak points seen on fluorescein angiography.

Corticosteroids (Exogenous and Endogenous)

Corticosteroid exposure — by any route (systemic, inhaled, intranasal, topical skin, epidural, intra-articular) — is the most consistently identified exogenous precipitant. Glucocorticoids activate mineralocorticoid receptors (MRs) on choroidal endothelium and RPE cells, increasing vascular permeability and driving the pachychoroid phenotype. Even inhaled corticosteroids and topical dermatological steroids applied at distant sites have been associated with CSCR onset and recurrence. Endogenous hypercortisolism (Cushing's syndrome) produces a particularly severe, bilateral, and chronic form.

Psychological Stress and Sympathomimetic Activation

The association with Type A personality, chronic psychological stress, and elevated plasma cortisol is well established. Stress-induced cortisol elevation may activate the same mineralocorticoid receptor pathway as exogenous corticosteroids. Sympathomimetic medications (ephedrine, pseudoephedrine) and conditions of high adrenergic tone have also been implicated.

Other Aetiological Associations

• Obstructive sleep apnoea (OSA): chronic nocturnal hypoxia and catecholamine surges; CSCR patients have a significantly higher prevalence of OSA
• Helicobacter pylori infection: association described in some studies; mechanism may involve endothelin-1 elevation increasing choroidal vascular permeability; evidence remains debated
• Pregnancy (third trimester): elevated cortisol and aldosterone; bilateral CSCR has been reported; typically resolves post-partum
• Systemic lupus erythematosus (SLE) and organ transplantation: high-dose corticosteroid use in these contexts is a major precipitant
• Hypertension: associated but may reflect shared risk factors with the stress/cortisol axis
• Psychotropic medications: some antipsychotics and antidepressants reported as precipitants

1. Pachychoroid: The Structural Foundation

The core abnormality is dilatation of the large outer choroidal vessels (Haller layer) with secondary attenuation of the overlying choriocapillaris. Dilated Haller layer vessels compress the choriocapillaris, reducing its perfusion and creating a paradox of localised ischaemia in the presence of overall choroidal congestion. The total choroidal thickness is typically >300 μm (normal: ~250 μm), detectable on enhanced depth imaging OCT (EDI-OCT).

2. Choroidal Hyperpermeability

Indocyanine green angiography (ICGA) demonstrates the pathognomonic finding of choroidal hyperpermeability — areas of delayed arterial filling followed by prolonged and increased fluorescence in the late phase, corresponding to the dilated engorged choroidal vessels. This represents increased hydrostatic pressure within the outer choroidal vasculature.

3. Mineralocorticoid Receptor Activation

Glucocorticoids can bind to and activate mineralocorticoid receptors (MRs) expressed on RPE cells, choroidal vascular endothelium, and Müller cells. MR activation upregulates vasodilatory factors (prostacyclin, nitric oxide) and increases vascular permeability through downregulation of occludin and ZO-1 tight junction proteins. This provides the mechanistic link between corticosteroid exposure and CSCR, and is the therapeutic rationale for mineralocorticoid receptor antagonists (eplerenone, spironolactone).

4. RPE Dysfunction and Outer Blood-Retinal Barrier Failure

Elevated choroidal hydrostatic pressure exerts mechanical and metabolic stress on the overlying RPE. At the weakest or most susceptible point — often a site of pre-existing RPE thinning or a pre-existent small pigment epithelial detachment (PED) — the RPE tight junctions fail. This constitutes a focal breakdown of the outer blood-retinal barrier. Protein-rich fluid from the choroid passes through the incompetent RPE into the subretinal space.

5. Neurosensory Retinal Detachment

Fluid entering the subretinal space accumulates between the photoreceptor outer segments and the RPE, separating the neurosensory retina from its metabolic support layer. The result is a dome-shaped serous detachment of the macula. Unlike CME (intraretinal) or tractional detachment (no fluid), CSCR detachment is entirely subretinal, with an intact overlying neurosensory retina — a key distinguishing feature on OCT.

6. FFA Leakage Patterns

On fluorescein angiography, the focal RPE defect produces characteristic leakage patterns as dye under hydrostatic pressure is forced through the RPE:

• Smokestack pattern (classic, ~10–20%): early focal hyperfluorescence at the RPE defect that expands vertically upward into the subretinal space, then spreads laterally — resembling a chimney smokestack; driven by pressure differential
• Inkblot pattern (~80–90%): more common; focal hyperfluorescence that expands concentrically from the RPE defect site, like ink spreading on blotting paper; slowly expands throughout the study

7. Photoreceptor Compromise

Separated from the RPE, photoreceptors lose access to the visual cycle retinoid transport, oxygen delivery, and outer segment phagocytosis. Prolonged detachment causes progressive outer nuclear layer thinning, ellipsoid zone disruption, and irreversible photoreceptor loss — the structural basis of permanent visual impairment in chronic CSCR.

Demographic Factors

• Male sex: male predominance of 6:1 to 10:1 in acute CSCR; chronic CSCR has a more balanced sex ratio, with older females more commonly affected than in acute disease
• Age: acute CSCR peaks at 25–50 years; chronic CSCR tends to affect an older age group (40–60 years)
• Ethnicity: higher incidence in Asians (including East and South Asian populations) and Hispanics compared to Caucasians; rarer in Black individuals

Behavioural and Psychological Factors

• Type A personality: competitive, driven, time-pressured, perfectionist behaviour patterns consistently associated with CSCR
• Psychological stress: acute and chronic stress are precipitants; elevated 24-hour urinary cortisol has been demonstrated in CSCR patients
• Sleep deprivation and shift work: dysregulation of cortisol diurnal rhythm

Medical and Pharmacological Factors

• Corticosteroid use: any route — systemic, inhaled, intranasal, topical skin preparations, epidural, intra-articular; even short courses of topical steroids applied to distant skin sites can precipitate CSCR in susceptible individuals
• Obstructive sleep apnoea: nocturnal hypoxia and adrenergic surges; highly prevalent in male CSCR patients
• Systemic hypertension: associated; may share mechanisms with sympathetic activation and cortisol dysregulation
• Cushing's syndrome: endogenous hypercortisolism; CSCR is a recognised ocular complication; bilateral and severe
• Organ transplantation: high-dose immunosuppressive steroids post-transplant are a major precipitant
• Helicobacter pylori: serological association in some studies; testing and eradication may reduce recurrence in seropositive patients
• Pregnancy (third trimester): elevated mineralocorticoid levels and cortisol; CSCR typically resolves post-partum
• Sympathomimetic medications: pseudoephedrine, ephedrine, sildenafil, certain antihistamines
• Prior episode of CSCR: strongest predictor of recurrence

Slit-Lamp Biomicroscopy (Contact Lens / Volk Lens)

• Serous macular detachment: a dome-shaped elevation of the foveal region is visible with a contact lens; the foveal reflex is absent or diminished; the elevated retina has a distinctive glistening or yellowish sheen compared to the surrounding attached retina
• Circumscribed shadow ring: a circular or ovoid shadow (the detachment margin) surrounds the serous elevation — visible as a darker arc on the fundus
• Focal RPE changes: a small yellowish or greyish subretinal dot at the leak point may be visible (the PED or RPE defect site)
• Subretinal precipitates: in chronic CSCR, fibrin deposits, lipid, or yellowish subretinal material may accumulate at the base of the detachment
• Anterior segment: normal; no cells or flare (distinguishing from uveitic conditions)

Fundus Camera Imaging Signs

• Colour fundus photography: oval or circular area of retinal elevation at the fovea; subtle pallor or glistening sheen to the detached area; RPE changes (atrophy, gravel-like deposits) in chronic CSCR; may appear almost normal in mild acute cases
• Fundus autofluorescence (FAF): in chronic CSCR, characteristic descending gravitational tracts of RPE atrophy below the detachment (hypoautofluorescent vertical streaks from subretinal fluid tracking inferiorly); hyperautofluorescent patches from subretinal deposits
• Fluorescein angiography (FFA): focal hyperfluorescence at the RPE defect site with classic smokestack or inkblot leakage pattern in late frames; in chronic CSCR, widespread RPE window defects (transmission hyperfluorescence) from RPE atrophy
• ICGA: choroidal hyperpermeability (late-phase hyperfluorescence of dilated Haller layer vessels); hypofluorescent areas representing dilated vessel lumens in early frames (blocked fluorescence from vessel walls)

OCT Signs (Diagnostic Standard)

• Dome-shaped subretinal fluid (SRF): hyporeflective space between the neurosensory retina and RPE; the key diagnostic feature; clear fluid without intraretinal cysts (distinguishing from CME)
• Intact neurosensory retina overlying SRF: retinal layers are intact above the fluid — no cysts, no epiretinal membrane, no intraretinal pathology (in uncomplicated acute CSCR)
• Pigment epithelial detachment (PED): focal dome-shaped elevation of the RPE with hyporeflective or moderately reflective material beneath; represents the primary RPE defect/leak site; may have a fibrinous or serous content
• Choroidal thickening (pachychoroid): on EDI-OCT (enhanced depth imaging OCT) or swept-source OCT, the subfoveal choroidal thickness is typically >300 μm; dilated Haller layer vessel lumens appear as hyporeflective ovals
• EZ (ellipsoid zone) integrity: intact in acute CSCR; disrupted or absent in chronic CSCR indicating photoreceptor damage
• ONL (outer nuclear layer) thinning: in prolonged chronic CSCR

Symptoms in CSCR arise from physical separation of photoreceptors from the RPE, disrupting the optical geometry and metabolic support of the foveal cone mosaic. Onset is typically subacute (days to weeks). In acute CSCR, symptoms are often milder than the clinician might expect given the degree of subretinal fluid, reflecting the slow time-course of photoreceptor compromise.

Characteristic Symptoms

• Blurred or hazy central vision: the most common presenting complaint; typically mild to moderate in acute disease (VA often 6/9 to 6/18); patients often describe “looking through water” or a “blur in the middle” of vision
• Micropsia: objects appear smaller than they actually are; caused by photoreceptors being physically spread apart by the subretinal fluid — a characteristic and near-pathognomonic symptom of serous macular detachment
• Metamorphopsia: straight lines appear wavy, curved, or distorted; detectable on the Amsler grid; due to photoreceptor displacement by fluid
• Central relative scotoma: a grey or dark patch in the centre of vision; may be subtle in early disease; worsens in chronic CSCR as photoreceptors degenerate
• Altered colour perception: subtle dyschromatopsia; colours may appear slightly different between the affected and fellow eye
• Positive after-image phenomenon: after looking at a bright light, the normal negative after-image takes longer to fade in the affected eye; patients notice this when comparing both eyes
• Reduced contrast sensitivity: difficulty with low-contrast tasks (driving in fog, reading in dim conditions) even when Snellen acuity is near normal
• Hyperopic shift: the serous detachment displaces the retina forward, producing a myopic effect — or paradoxically improves acuity in a myopic patient — the retina is pushed toward the lens, effectively reducing the axial length in the serous zone
• Photophobia: occasionally; especially if the detachment is large

Notably, many patients present saying their vision “improved” after using a plus lens (reading glasses) — a characteristic feature of the relative hyperopic shift from the serous detachment pushing the retina anteriorly.

• Chronic CSCR with permanent vision loss: the primary long-term complication; approximately 30–50% of patients with chronic CSCR develop permanent moderate visual impairment; caused by progressive RPE degeneration and photoreceptor loss
• RPE atrophy (gravitational tracts): in chronic CSCR, subretinal fluid tracks inferiorly under gravity, depositing fibrin, lipofuscin, and inflammatory products that damage the RPE; characteristic downward “falling water marks” or “descending tracts” of RPE atrophy visible on FAF and colour fundus photography
• Ellipsoid zone (IS/OS) disruption: fragmentation or loss of the photoreceptor ellipsoid zone on OCT after prolonged SRF; a structural marker of irreversible photoreceptor damage and poor visual prognosis
• Outer nuclear layer (ONL) thinning: progressive reduction in photoreceptor cell body density correlating with chronic SRF duration
• Pachychoroid neovascularisation (PNV) / Type 1 CNV: in chronic CSCR, the RPE atrophy and choroidal congestion promote development of type 1 choroidal neovascularisation (sub-RPE, flat CNV); may be occult on FFA but visible on OCTA; may convert to exudative (type 2) CNV with rapid vision deterioration
• Recurrence: 30–50% of patients experience recurrent episodes over a 10-year period; each recurrence carries incremental risk of RPE and photoreceptor damage
• Subretinal deposits and lipid exudates: in chronic bullous CSCR, protein-rich subretinal fluid desiccates to form subretinal precipitates; lipid deposits may accumulate around the fovea
• Secondary cystoid macular edema: uncommon; may develop if fluid re-enters through the RPE after PED rupture or with treatment

CSCR is strongly linked to systemic conditions that dysregulate the cortisol-mineralocorticoid axis, alter autonomic tone, or require corticosteroid therapy. Identifying and managing systemic associations is integral to CSCR management.

Cushing's Syndrome

Endogenous hypercortisolism from any cause (pituitary adenoma, adrenal adenoma, ectopic ACTH) produces a particularly aggressive, bilateral, and recurrent form of CSCR. Bilateral CSCR in a patient without exogenous steroid use should prompt evaluation for Cushing's syndrome (24-hour urinary free cortisol, overnight dexamethasone suppression test, late-night salivary cortisol, pituitary MRI). Effective treatment of Cushing's syndrome often leads to resolution of CSCR.

Corticosteroid-Dependent Conditions

• Organ transplant recipients: high-dose systemic corticosteroids (prednisolone, methylprednisolone) for immunosuppression are a leading cause of severe and bullous CSCR; steroid dose reduction (where medically feasible) is the primary intervention
• Systemic lupus erythematosus (SLE): CSCR has been reported in lupus patients on corticosteroid therapy, though lupus retinopathy itself is a separate entity
• Asthma and COPD: inhaled corticosteroids are an under-recognised cause; patients using both inhaled and systemic steroids are at highest risk
• Allergic and inflammatory conditions: topical corticosteroid skin preparations applied to the face, scalp, or even distant sites can trigger CSCR in susceptible individuals

Obstructive Sleep Apnoea (OSA)

OSA is significantly more prevalent in male CSCR patients than in age-matched controls. Chronic nocturnal hypoxia and associated cortisol and catecholamine surges activate the mineralocorticoid receptor pathway in the choroid. CSCR patients — especially males — should be screened for OSA symptoms (snoring, witnessed apnoeas, daytime somnolence, morning headache) and referred for polysomnography where appropriate. CPAP therapy for OSA may reduce CSCR recurrence in some patients.

Helicobacter pylori

Several studies have described a higher seroprevalence of H. pylori in CSCR patients compared to controls. The proposed mechanism involves H. pylori-induced elevation of plasma endothelin-1, which increases choroidal vascular tone and permeability. Some case series report resolution or improvement of CSCR following H. pylori eradication therapy. Testing (urea breath test, stool antigen, serology) and eradication in seropositive CSCR patients is reasonable, particularly for recurrent cases.

Pregnancy

CSCR typically occurs in the third trimester, when cortisol and aldosterone levels are at their peak. It is almost always bilateral and resolves post-partum. Anti-VEGF therapy and PDT are contraindicated in pregnancy; observation is the only safe management in most cases. Recurrence in subsequent pregnancies is common.

Diagnosis is primarily clinical and imaging-based. OCT is the diagnostic cornerstone for detecting and quantifying SRF and assessing choroidal anatomy. FFA and ICGA provide functional information about the RPE leak point and choroidal vasculature.

Clinical History

• Age, sex, and ethnicity (young-middle aged male in most acute cases)
• Nature of visual symptoms: micropsia, metamorphopsia, central blur — classic triad
• Detailed corticosteroid exposure history: systemic, inhaled, intranasal, topical, epidural, ophthalmic drops
• Psychological stress, occupation (high-stress professions: physicians, traders, executives, military)
• Sleep symptoms (OSA screening)
• History of previous episodes
• Pregnancy status in females

Visual Function Testing

• BCVA: often 6/9 to 6/18 in acute disease; a +1.00 to +2.00 D pinhole or trial frame may improve acuity (hyperopic shift from retinal elevation)
• Amsler grid: metamorphopsia and central relative scotoma detectable; useful for patient self-monitoring
• Contrast sensitivity: often disproportionately reduced relative to Snellen acuity
• Microperimetry: maps relative scotoma and fixation stability; useful for chronic CSCR monitoring

OCT (Primary Imaging Tool)

• Spectral-domain OCT: diagnostic standard; demonstrates dome-shaped hyporeflective SRF between neurosensory retina and RPE; focal PED at the leak point; intact inner retinal layers (no intraretinal cysts)
• Enhanced depth imaging OCT (EDI-OCT) / swept-source OCT: essential for measuring subfoveal choroidal thickness (>300 μm in pachychoroid); identifying dilated Haller layer vessel lumens
• OCT-angiography (OCTA): identifies type 1 CNV (flow signal beneath RPE) in chronic CSCR; differentiates from pachychoroid neovasculopathy; avoids dye injection
• Key OCT parameters to report: subfoveal SRF height, subfoveal choroidal thickness (SFCT), EZ integrity, PED morphology, ONL thickness

Fluorescein Angiography (FFA)

• Identifies and localises the RPE leak point — essential for planning focal laser treatment in extrafoveal cases
• Classic patterns: smokestack (10–20%) or inkblot (80–90%) leakage
• In chronic CSCR: window defects from RPE atrophy; widespread hyperfluorescence from multiple leaks
• Differentiates CSCR from CME (petaloid vs. inkblot/smokestack), AMD CNV (irregular CNV vs. focal inkblot), and VKH (extensive diffuse RPE leaks)

Indocyanine Green Angiography (ICGA)

• Gold standard for visualising choroidal vasculature and demonstrating choroidal hyperpermeability
• Late-phase ICGA hyperfluorescence corresponds to dilated, permeable choroidal vessels (pachychoroid); this area is the treatment target for PDT
• Essential for guiding spot placement in half-dose PDT

Fundus Autofluorescence (FAF)

• Identifies RPE atrophy (hypoautofluorescence) and subretinal deposits (hyperautofluorescence)
• Characteristic “descending tracts” of gravitational RPE atrophy below the detachment — a hallmark of chronic CSCR

Management is guided by disease chronicity, leak point location, steroid exposure, and patient factors. Acute CSCR is managed conservatively; chronic CSCR requires active treatment.

1. Conservative Management (Acute CSCR <3–4 Months)

• Watchful waiting: over 90% of acute CSCR episodes resolve spontaneously within 3–4 months; observation with serial OCT monitoring (every 4–6 weeks) is appropriate for first episodes of limited duration
• Eliminate corticosteroid exposure: taper or discontinue any exogenous steroids in consultation with the prescribing physician; this is the single most important modifiable intervention; steroid cessation alone may resolve CSCR in many cases
• Stress reduction: patient education on stress management; sleep hygiene optimisation
• OSA treatment: CPAP therapy for confirmed OSA
• Avoid further precipitants: avoid corticosteroids, pseudoephedrine, sildenafil, and other precipitants during and after an episode

2. Half-Dose / Half-Fluence Verteporfin PDT (Gold Standard for Chronic CSCR)

• Photodynamic therapy (PDT) with verteporfin targets the hyperpermeabile choroidal vessels, inducing thrombosis and remodelling of the dilated Haller layer vessels, restoring normal choriocapillaris perfusion and reducing hydrostatic pressure on the RPE
• Half-dose PDT (3 mg/m² verteporfin, 50% of standard dose) or half-fluence PDT (25 J/cm², 50% standard fluence) — used to reduce risk of RPE atrophy from over-treatment compared to standard-dose PDT
• Treatment spot is guided by the area of ICGA hyperfluorescence (choroidal hyperpermeability zone) rather than the FFA leak point alone
• The PLACE trial (van Dijk et al., 2018): half-dose PDT was superior to high-density subthreshold micropulse laser (HSML) at 7 weeks; more complete SRF resolution and better VA gains with PDT
• Complete SRF resolution rates of 80–90% with half-dose PDT; most improvement occurs within 4–12 weeks of treatment
• Risk of over-treatment: RPE atrophy, secondary CNV, choroidal ischaemia — hence half-dose/half-fluence protocols are preferred over standard PDT

3. High-Density Subthreshold Micropulse Laser (HSML)

• Laser energy delivered in microsecond pulses, treating RPE without visible burn or permanent tissue damage
• Can be applied even over the fovea (unlike conventional laser); targets the RPE at the leak site
• Efficacy inferior to half-dose PDT in the PLACE trial; resolution rates approximately 30–40% at 7 weeks
• Used when PDT is unavailable, as adjunct, or in patients where PDT is contraindicated

4. Focal Laser Photocoagulation

• Conventional (threshold) laser applied to the FFA-identified RPE leak point
• Effective in accelerating SRF resolution in acute CSCR with extrafoveal leak points (>300 μm from the centre)
• Absolutely contraindicated for foveal or juxtafoveal leak points — creates permanent scotoma
• Not recommended for chronic CSCR (multiple diffuse leaks); rarely used as first-line given widespread PDT availability

5. Mineralocorticoid Receptor Antagonists (Off-Label)

• Eplerenone (25–50 mg/day) or spironolactone (25–50 mg/day): mineralocorticoid receptor blockade addresses the cortisol-mediated pathway directly
• Some retrospective case series showed modest SRF reduction; however the VICI randomised trial (Bousquet et al., 2015) showed eplerenone was not significantly superior to placebo at 3 months for chronic CSCR
• Some physicians use as adjunct or in cases where PDT is not available or in milder chronic disease; uncertain efficacy based on current evidence
• Monitor for hyperkalaemia, particularly in patients with renal impairment

6. Anti-VEGF Therapy

• Not indicated for primary CSCR without CNV
• Intravitreal anti-VEGF (ranibizumab, bevacizumab, aflibercept) used for secondary CNV complicating chronic CSCR — particularly pachychoroid neovasculopathy converting to exudative disease

7. H. pylori Eradication

• Test for H. pylori in recurrent or chronic CSCR (urea breath test or stool antigen); eradicate with standard triple therapy if positive
• Adjunctive measure; evidence limited but low-risk intervention

Prognosis depends critically on the duration of SRF, the degree of RPE and photoreceptor damage at the time of treatment, and the adequacy of treatment of precipitating factors.

Acute CSCR

• Spontaneous resolution in >90% within 3–4 months; mean VA at resolution typically 6/9 or better
• Most patients regain baseline VA; however subtle deficits in contrast sensitivity, colour perception, and reading speed frequently persist even after complete anatomical resolution
• The vision achieved after first-episode acute CSCR is excellent, but subtle functional deficits remain in many patients

Chronic CSCR

• Approximately 30–50% of patients with chronic CSCR develop permanent moderate visual impairment (VA <6/12) in the affected eye
• Half-dose PDT resolves SRF in 80–90% of treated cases; VA improvement depends on pre-treatment EZ integrity and ONL thickness
• Visual gains after PDT are better when treatment is given before significant EZ disruption — reinforcing the importance of timely intervention at the 3–4 month threshold
• Even after complete SRF resolution, subtle contrast sensitivity and reading speed deficits often persist from subclinical photoreceptor damage

Recurrence

• Recurrence rate: approximately 30–50% over 10 years; higher in patients who continue corticosteroid use, have untreated OSA, or have bilateral pachychoroid
• Each recurrent episode carries incremental risk of cumulative RPE and photoreceptor damage
• Fellow eye involvement: bilateral pachychoroid in many patients; fellow eye subclinical changes detectable in up to 40%; clinical CSCR in the fellow eye in 10–15% of cases

Key Prognostic OCT Markers

• Ellipsoid zone (EZ) integrity: primary predictor of final visual outcome; disrupted EZ indicates irreversible photoreceptor loss
• Outer nuclear layer (ONL) thickness: thinning correlates with chronicity and visual prognosis
• SRF height and extent: larger SRF at presentation is associated with longer resolution time but not necessarily worse final VA if treated promptly
• Subfoveal choroidal thickness: very thick choroids may predict higher recurrence risk but do not independently predict final visual outcome