Certified Ophthalmic Medical Technologist (COMT) Practice Exam

What term describes an area where decreased pigment in the retinal pigment epithelium allows normal fluorescence of the choroid to shine through?

1. Leakage defect

2. Window defect

3. Block defect

4. Transmission defect

The correct answer is: Window defect

The term that describes an area where decreased pigment in the retinal pigment epithelium allows normal fluorescence of the choroid to shine through is known as a window defect. This phenomenon occurs when there is a loss of pigment in the retinal pigment epithelium, which typically absorbs light and helps to reduce background fluorescence. When this pigment is reduced or absent, the underlying choroidal fluorescence can be seen more clearly during fluorescein angiography. In contrast to other terms, a window defect is characterized specifically by the visibility of the choroidal fluorescence due to a thinning or absence of the pigment epithelium layer. This can often be observed in conditions like fundus flavimaculatus or other retinal degenerations where pigment loss is prominent. Other terms such as "leakage defect," "block defect," and "transmission defect" refer to different processes in the context of retinal imaging or pathology. Leakage defects involve pathological leakage of dye from blood vessels, block defects refer to areas where the retinal pigment epithelium blocks fluorescence (often due to the presence of hemorrhage or other lesions), and transmission defects relate to the reduced transmission of light through media opacities. Thus, window defect is the most appropriate term