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8/10/2019 diabeticmacularedema-131228074443-phpapp02

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DIABETIC MACULAR EDEMA


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OVERVIEW

Most common cause of visual loss in DM

Prevelance 11.1% (2-10%)

Incidence (10 year rate: 20.1%; 25.4%; 13.9%)


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CLINICAL ASSOCIATONS

Severity of DR

Duration of diabetes and glycemic control

Proteinuria,

Hypertension,

Dyslipidemia

Pregnancy,

Intraocular surgery

Pan retinal photocoagulation


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ANATOMY


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ANATOMY


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PATHOPHYSIOLOGY

ALDOSE REDUCTASE

VASOPROLFERATIVE FACTORS

PLATELET DYSFUNCTION


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PATHOPHYSIOLOGY

Capillary damage and raised permeability

(breakdown of inner blood retinal barrier)

Pericyte loss (oxidative damage and AGEs)

Disorganisation of tight junctions

Increased transcelluar endocytosis

VEGF

Protein kinase c

Microaneurysms

IRMAs


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PATHOPHYSIOLOGY

Extracellular fluid accumulation

Cystoid spaces in the outer plexiform layer

May occupy entire thickness

Tissue disorganisation Atrophic changes


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PATHOPHYSIOLOGY

Hard exudates (HE):

Lipoproteinaceous deposits

Transudation

Outer plexiform layer

Subretinal fluid

Subretinal fibrosis


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PRESENTATION

Depends on central macular involvement

Paracentral scotomas

Gradual progressive loss of vision (weeks to

months) Color vision loss

Metamorphopsia

Fluctuation of vision

Contrast sensitivity

Prolonged adaptation


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EXAMINATION

Clinically best detected by 60 D, 78 D lenses

Decreased translucency

Loss of foveolar reflex Patterns :

Diffuse

Focal; circinate pattern Ischemic

Mixed


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CSME

Retinal thickening atthe center of macula

Retinal thickeningand/or adjacent hard

exudates at or within500 u of center ofmacula

Retinal thickening 1

disc area, any part ofwhich is within 1 DD ofthe center of macula


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THERAPY

Medical

LASER photocoagulation

Triancinolone acetonide Anti-VEGF therapy

Protein kinase c inhibtion

Vitrectomy


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ETDRS gave conclusive supporting proof

Focal laser for leaking microaneurysm atleast

500 u from the fovea

(aim : closure of leak)

Grid laser for diffuse retinal thickening/ areas

of ischemia

(aim : stimulate retinochoroidal pump)


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Treatable lesions

Focal leaks >500 u from center of macula

causing thickening/exudation

Focal leaks 300-500 u from center if t/t is not

likely to damage perifoveal capillary network

Areas of diffuse leakage

Abnormal avasular zone


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ETDRS protocol

Focal Grid

Spot size 50-100 u


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Adverse effects

Foveal burns

Subretinal hemorrhage

Vitreous hemorrhage

RPE creep

CNV

Paradoxically increased HE


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TRIANCINOLONE ACETONIDE

Intravitreal route

Needs repeated injections

Duration of effect : 2-3 months with 4mg Complications

Raised iop

Endophthalmitis Cataracts

Peribulbar route


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ANTI-VEGF therapy

Bevacizumab (Avastin)

Ranibizumab (Lucentis)

Fusion proteins with human antibody backbone

Bind all VEGF subtypes

Intravitreal route

No definite schedule

Pegaptinib (Macugen) Engineered RNA fragment

Specific sites for VEGF binding


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PROTEIN KINASE C Inhibitors

PKC

Ruboxistaurin

Oral administration

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