Objectives

Upon completion of BCSC Section 12, Retina and Vitreous, the learner should be able to

describe the basic structure and function of the retina and its relationship to the pigment epithelium, choroid, and vitreous

select appropriate methods of examination and ancillary studies for the diagnosis of vitreoretinal disorders

identify specific pathologic processes that affect the choroid, retina, or vitreous

describe the principles of medical and surgical treatment of vitreoretinal disorders

incorporate data from major prospective clinical trials in the management of vitreoretinal disorders whenever possible

Introduction

The retina is the delicate neuroepithelium that lines the posterior aspect of the eye, adhering firmly to the optic nerve head posteriorly and to the ora serrata anteriorly. Divided into central and extra-areal periphery, this layer of modified sensory cilia serves important aspects of visual function:

detail discrimination color perception

vision in dim illumination peripheral vision

The vitreous is the transparent structure that fills the posterior segment eye cavity and is composed of connective tissue, predominantly type II collagen, glycosaminoglycans, and hyaluronic acid. It plays an important role in many diseases of the posterior segment. Understanding its structure and the changes it can undergo with aging is key to understanding many vitreoretinal disorders.

BCSC Section 12, Retina and Vitreous, is arranged into 3 parts. Part I, Fundamentals and Diagnostic Approaches, covers retinal anatomy, imaging, and functional evaluation in 3 chapters. Chapter 1 provides an overview of the anatomy of the posterior segment. Chapter 2 discusses techniques of examination, including dilated slit-lamp biomicroscopy in combination with precorneal non-contact or contact lenses, and indirect ophthalmoscopy, often aided by scleral indentation to facilitate viewing the anterior retina.

Documenting clinical findings, either descriptively or by illustration, remains an essential element of a complete posterior segment examination. In addition, ancillary tests, such as fundus autofluorescence, fluorescein angiography, indocyanine green angiography, optical coherence tomography (OCT), scanning laser ophthalmoscopy, microperimetry, and electrophysiology, may provide additional diagnostic information. Optical coherence tomography in its various incarnations (time-domain, spectral-domain, and swept-source OCT) deserves special mention, as it has become perhaps the most commonly ordered ancillary ophthalmic test and is revolutionizing the understanding of many vitreoretinal conditions.

Chapter 3 reviews electrophysiologic tests and their significance in diagnosis and follow-up of retinal disease. Ultrasonography, or echography, employing both A- and B-scan techniques, is useful for patients with opaque media, can aid in the diagnosis of retinal or choroidal lesions, and can be used to monitor a lesion’s size.

Depending on their location, developmental or acquired alterations in the posterior segment may or may not be symptomatic. Many vitreoretinal diseases, such as diabetic retinopathy or age-related macular degeneration, may be asymptomatic until the more advanced stages are reached. Vitreoretinal disease symptoms, when they occur, may include the following:

transient or persistent reduction in visual acuity dyschromatopsias (alterations in color vision or perception)

delayed photostress recovery (delayed adaptation to reduced lighting) photophobia

metamorphopsia (wavy or distorted vision) floaters

photopsia (flashes) scotomata (blind spots/areas) loss of visual field nyctalopia (night blindness)

Part II, Disorders of the Retina and Vitreous, discusses specific diseases of and trauma to the posterior segment in Chapters 4 through 17. Appropriate diagnostic techniques are indicated throughout these discussions. By necessity, the illustrative findings associated with the described vitreoretinal disorders are presented as highlights–using schematics as well as the different imaging technologies–rather than as a comprehensive collection. Narratives describing the management of, and therapy for, the retinal disorders covered in Part II are complemented by descriptions of many important clinical trials that have helped establish appropriate evidence-based practices.

Part III, Selected Therapeutic Topics, offers more detailed information in Chapters 18 and 19 on the 3 most important posterior segment treatment approaches: vitreoretinal surgery, laser surgery, and intravitreal injection of effective pharmacologic agents, especially anti-vascular endothelial growth factor treatments. The emergence of each of these treatment approaches has been associated with dramatic improvements in the outcomes retina specialists can accomplish in terms of preserving or restoring vision for our patients.

Increasingly, when treating patients with vitreoretinal disorders, clinicians are basing treatment decisions on evidence from clinical trials. Readers should familiarize

themselves with topics important for interpreting the scientific literature, such as study design, levels of evidence, results interpretation, and clinical practice applications of trial results (see BCSC Section 1, Update on General Medicine, Chapter 1).

This book is not meant as a thorough review of the field but rather serves as what a group of experts considers the most important highlights of the specialty. Thus, readers interested in more comprehensive information can obtain additional detail from the selected references as well as from references that appear at the end of the book under Basic Texts. Lastly, a new feature with this edition is the inclusion of videos to better illustrate specific topics; these edited clips are accessible through the print and electronic forms of this volume.