Elsevier

Survey of Ophthalmology

Volume 49, Issue 5, September–October 2004, Pages 470-490
Survey of Ophthalmology

Major review
Macular edema

https://doi.org/10.1016/j.survophthal.2004.06.002Get rights and content

Abstract

Macular edema is the final common pathway of many intraocular and systemic insults. It may develop in a diffuse pattern where the macula appears generally thickened or it may acquire the characteristic petaloid appearance referred to as cystoid macular edema. Although macular edema may be associated with protean underlying conditions, it is most commonly seen following intraocular surgery, venous occlusive disease, diabetic retinopathy, and posterior segment inflammatory disease. As well as clinical suspicion, a wide range of investigations may lead to the diagnosis of macular edema. Fluorescein angiography and optical coherence tomography provide enhanced visualization of the geometry and distribution of macular edema. A variety of approaches to the treatment of macular edema have been attempted, with a variable degree of success. These options have included topical and systemic steroids, topical and oral non-steroidal anti-inflammatory agents and laser photocoagulation treatment. More recently other therapeutic modalities, including immunomodulators, intravitreal injection of triamcinolone, and pars plana vitrectomy have also been employed. Clinical trials are currently looking into the use of a steroid slow-release intravitreal device for the management of macular edema secondary to uveitis and diabetes. This article reviews the clinical entity of macular edema focusing on the current therapeutic strategies for its management.

Introduction

Macular edema represents a common pathologic sequel of the retina associated with a broad spectrum of potential insults. It consists of a localized expansion of the retinal intracellular and/or extracellular space in the macular area. This predilection to the macular region is probably associated with the loose binding of inner connecting fibers in Henle's layer, allowing accumulation of fluid leaking from perifoveal capillaries. The absence of Müller cells in the foveal region is also a contributing factor.

Radially orientated cystoid spaces consisting of ophthalmoscopically clear fluid are often clinically detectable in the macular area. The cysts are characterized by an altered light reflex with a decreased central reflex and a thin, highly reflective edge (Fig. 1).66 Histological studies show the cysts to be areas of retina in which the cells have been displaced. Recently Antcliff et al15 monitored the hydraulic conductivity of the human retina following progressive ablation of retinal layers performed with the aid of an excimer laser. They concluded that the inner and outer plexiform layers constitute high resistance barriers to fluid flow through the retina, which accounts for the characteristic distribution of cystoid macular edema (CME) seen in histological specimens and with optical coherence tomography (OCT).

In this review the etiology and investigative methods for the diagnosis and monitoring of macular edema are presented with an emphasis on current therapeutic modalities based on evidence from existing literature.

Section snippets

Etiology and Clinical Manifestations

A multitude of underlying conditions may result in macular edema. In this section the most common causes of macular edema are described with reports on its clinical manifestation in different clinical settings.

Investigations

Slit-lamp examination with contact or non-contact lens, makes it possible to detect retinal thickening, localized or extending to the posterior pole. The use of a narrow slit beam is useful in detecting cystoid spaces. Clinical suspicion of macular edema can be confirmed with the aid of a wide variety of investigations (Table 1). Tests may be grouped into three categories according to whether one is analyzing the underlying pathogenesis, the effect of the macular edema on the retina, or its

Medical

The challenge concerning the management of macular edema arises in the chronic and persistent case, for which a stepwise therapeutic approach is optimal. The clinician must always be alert to the possible side effects of the many effective, but potentially toxic, pharmaceutical agents used to treat this entity. Additionally, surgical management should be considered for unremitting cases of CME (Table 2).

Method of Literature Search

In this review, we identified pertinent articles on macular edema from a combination of sources including electronic database searches and manual searches through the literature. A computerized search of the PubMed database (National Library of Medicine) was performed up to January 2003. The term macular edema was used for a broad and sensitive search. Subsequently all the abstracts were carefully scanned and were divided into subcategories covering topics including pathogenesis, etiology,

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