Report

Intravitreal Bevacizumab in Myopic Neovascular Membranes: 24-Month Results

Myopia is a highly frequent ocular disorder worldwide and pathologic myopia is the 4th most common cause of irreversible blindness in developed countries. Pathologic myopia is especially common in East Asian countries. Ocular alterations associated with pathologic myopia, especially those involving the macular area—defined as myopic maculopathy—are the leading causes of vision loss in patients with pathologic myopia.

High myopia is defined as the presence of a highly negative refractive error (>−6 to −8 diopters) in the context of eye elongation (26–26.5 mm). Although the terms high myopia and pathologic myopia are often used interchangeably, they do not refer to the same eye disease. The two key factors driving the development of pathologic myopia are: 1) elongation of the axial length and 2) posterior staphyloma.

The presence of posterior staphyloma, which is the most common finding in patients with pathologic myopia, is the key differentiating factor between high and pathologic myopia. The occurrence of staphyloma will, in most cases, eventually lead to other conditions such as atrophic, traction, or neovascular maculopathy. Posterior staphyloma is for instance, responsible for the differences between a myopic macular hole (MH)—with and without retinal detachment—and idiopathic MH. Posterior staphyloma typically induces retinal layer splitting, leading to foveoschisis in myopic MH, an important differentiating factor between myopic and emmetropic MH.

Myopic maculopathy is a highly complex disease and current classification systems do not fully account for the numerous changes that occur in the macula of these patients. Therefore, a more comprehensive classification system is needed, for several important reasons. First, to more precisely define the disease stage to improve follow-up by enabling clinicians to more accurately monitor changes over time, which is essential given the progressive nature of this condition. Second, unification of the currently-available classification systems would establish standardized classification criteria that could be used to compare the findings from international multicentric studies. Finally, a more comprehensive classification system could help to improve our understanding of the genetic origins of this disease, which is clearly relevant given the interchangeable—but erroneous—use of the terms high and pathologic myopia in genetic research.

The aim of this article is to review and compile available information on the classification, pathophysiology, and clinical features of myopic choroidal neovascularization (CNV); to describe the latest data on the management of this disease; and to present guidance.

In the United States, myopia affects approximately 34 million people (2010), and similar figures have been reported in Europe. Pathologic myopia (PM), a possible consequence of myopia, is estimated to affect up to 3% of the global population. One of the most serious complications of PM is myopic CNV, which often leads to a sudden onset but progressive decline in central vision and is associated with a poor prognosis unless treated. Furthermore, 35% of patients with myopic CNV develop bilateral disease in the fellow eye within 8 years. Although intravitreal anti–vascular endothelial growth factor (VEGF) therapies have had a major impact on the management of patients with myopic CNV, there remain significant gaps in our understanding of this condition and how to best administer treatment. Additionally, the long-term safety and efficacy of these treatments are largely unknown.

We carried out a literature review (September 2015) of all English-language articles in PubMed resulting from searches of the following terms: “choroidal neovascularization” AND “myopia” OR “myopic macular degeneration” OR “degenerative myopia” OR “myopic maculopathy” OR “myopic retinopathy” OR “pathological myopia” OR “pathologic myopia.”

We screened a total of 566 abstracts, and 250 articles were deemed relevant for full publication review. We excluded a further 71, but an additional 44 articles were identified. This resulted in 223 articles being used to develop this review.

Highly myopic patients experiencing a sudden loss of central vision should be referred for further examination. Once a diagnosis of myopic CNV has been confirmed, after fluorescein angiography, treatment initiation should be prompt and anti-VEGF agents considered as first-line therapy, unless contraindicated. Continued monitoring of patients is required to assess any progression or recurrence of the condition.