American Board of Ophthalmology (ABO) Practice Exam 2025 - Free Ophthalmology Practice Questions and Study Guide

The distinction between the nonproliferative phase and the proliferative phase of diabetic retinopathy is primarily characterized by the presence of microaneurysms in the nonproliferative phase and the emergence of neovascularization in the proliferative phase.

In the nonproliferative phase, early changes include the formation of microaneurysms, which are small bulges in the retinal blood vessels. These can lead to localized hemorrhages, exudates, and retinal edema. The primary issues in this phase are related to the breakdown of the blood-retinal barrier, which does not necessarily involve the growth of new blood vessels.

In contrast, the proliferative phase is marked by neovascularization, which is the abnormal growth of new blood vessels on the retina or optic disc. This occurs as a response to ischemic conditions in the retina due to poor blood supply, often leading to further complications such as bleeding and retinal detachment.

The other options refer to different aspects of retinal health that do not accurately differentiate between the two phases. While retinal swelling and thinning can occur in diabetic retinopathy, they are not specific indicators to distinguish between the nonproliferative and proliferative phases. Similarly, issues regarding