What is the internal limiting membrane (ILM)?

What is the internal limiting membrane (ILM)?

• A. The boundary between the retina and vitreous.
• B. A vascular layer in the choroid.
• C. The photoreceptor outer segment layer.
• D. The boundary between the retina and sclera.

Answer: (A)

The inner limiting membrane is the boundary between the retina and the vitreous. It is the innermost retinal surface, formed by the foot processes of Müller glial cells, acting as the basement membrane that interfaces with the vitreous body. On OCT, it shows up as the bright line at the vitreoretinal interface, marking where the retina ends and the vitreous begins. It is not a vascular layer in the choroid, not the photoreceptor outer segment layer, and not the boundary with the sclera, so the correct description is the retinal–vitreous boundary.

The inner limiting membrane is the boundary between the retina and the vitreous. It is the innermost retinal surface, formed by the foot processes of Müller glial cells, acting as the basement membrane that interfaces with the vitreous body. On OCT, it shows up as the bright line at the vitreoretinal interface, marking where the retina ends and the vitreous begins. It is not a vascular layer in the choroid, not the photoreceptor outer segment layer, and not the boundary with the sclera, so the correct description is the retinal–vitreous boundary.