The boundary between retina and vitreous is which structure?

• A. Internal limiting membrane
• B. Outer limiting membrane
• C. Inner nuclear layer
• D. Choroid boundary

Answer: (A)

The boundary between the retina and the vitreous is the internal limiting membrane. This thin, basement-membrane layer sits on the inner surface of the retina and is formed mainly by the endfeet of Müller cells. It serves as the interface where the vitreous humor’s posterior surface (the posterior hyaloid) contacts the retina. In imaging like OCT, the internal limiting membrane appears as the innermost hyperreflective line, marking the vitreoretinal boundary. The other structures listed correspond to different retinal boundaries: the outer limiting membrane lies deeper, between photoreceptors and the outer nuclear layer; the inner nuclear layer is its own retinal layer; and the choroid boundary is at the retina–choroid interface behind the retina, not at the vitreous interface.