How does type II classic CNV compare in occurrence to type I occult CNV?

Type II classic choroidal neovascularization (CNV) generally occurs less frequently than type I occult CNV. Type II CNV is characterized by well-defined, typically more symptomatic lesions with a higher degree of exudation and hemorrhage. This type is often associated with conditions such as age-related macular degeneration (AMD) and other retinal diseases where overt neovascularization is apparent.

In contrast, type I occult CNV tends to be less visually apparent and is associated with a more subtle form of neovascularization. It occupies the plane beneath the retinal pigment epithelium and is often associated with less significant symptoms until significant retinal damage has occurred. Due to the nature of type I CNV, it manifests more frequently in patients, particularly in the context of AMD, making it a more common presentation compared to type II classic CNV.

Understanding this distinction helps in managing and anticipating the progression and treatment of CNV related to retinal diseases. The frequency of each type informs clinical decisions and patient prognostications.