Choroidal neovascularization (CNV) is a sight-threatening complication of many ocular diseases and typically requires therapy such as anti-VEGF agents in addition to treatment for the underlying cause. Distinguishing CNV secondary to inflammatory disease from CNV complicating other conditions is key, researchers say, as “the control of the underlying uveitis allows [it] to decrease the stimulus for new vessel proliferation and reduces the risk of reactivation of the inflammatory CNV. Rarely, inflammatory CNV can also be the only discernible sign of inflammatory/infectious diseases (such as ocular tuberculosis), and other features of intraocular inflammation may go unidentified because they are too subtle. In such cases, distinguishing inflammatory CNV from CNV due to other causes, such as AMD, is very critical.”

However, the presentation of inflammatory CNV is often similar to CNV associated with other conditions such as myopia or AMD on OCT. The pitchfork sign has been described as a feature of noninflammatory CNV eyes and inflammatory CNV eyes associated with multifocal choroiditis and with other uveitic conditions. “There is a need to identify features on OCT that can help in differentiating CNV related to conditions such as AMD, uveitis and myopia,” the authors of a paper published in Retina wrote. In their study, they analyzed OCT features of patients with different causes of CNV to identify characteristics to help pin down the underlying etiology and found that age plays a significant role.

The researchers collected demographic and clinical data of 185 eyes (179 patients) with treatment-naïve inflammatory CNV, myopic CNV and type 2 AMD-CNV for the study. Each patient underwent OCT evaluation to determine the presence of the following OCT signs: pitchfork sign, pigment epithelial detachment (PED), subretinal fluid (SRF), intraretinal cysts, subretinal hyperreflective material, atrophy and outer retinal disruption graded one to four.

When the researchers analyzed the influence of demographics on underlying etiology, they found that patient age had a significant effect on CNV appearance on OCT. The mean ages of those with inflammatory CNV, myopic CNV and AMD-CNV were 36, 61 and 77, respectively. The presence of pitchfork sign was significantly negatively associated with age, regardless of underlying disease. SRF, PED, intraretinal cysts and outer retinal disruption all demonstrated significant positive associations with age, regardless of gender and underlying disease.

The researchers concluded that age significantly affected OCT appearance of CNV, especially in the presence of pitchfork sign. They also noted that none of these OCT signs increased likelihood of an inflammatory CNV diagnosis. “The only two signs that affected the odds ratio for the diagnosis of a specific CNV etiology, given the age and gender of the subject, were the absence of SRF that increased the likelihood of myopic CNV and the presence of SRF and PED that suggested a diagnosis of AMD-CNV,” the researchers wrote in their paper.