IS/OS refers to which parts of the photoreceptors?

IS/OS refers to which parts of the photoreceptors?

• A. Inner segment / outer segment
• B. Inner segment and outer retina
• C. Inner segment / inner sclera
• D. Intraocular surface / outer surface

Answer: (A)

IS/OS denotes the boundary between the photoreceptor inner segment and outer segment. The inner segment carries the cell’s metabolic machinery, while the outer segment contains the photopigment discs that actually detect light. On OCT this boundary appears as a distinct, bright line and is a key marker of photoreceptor integrity. If this junction is disrupted or poorly defined, it often correlates with reduced visual function. The other terms would describe broader regions (outer retina, sclera, surface tissues) that aren’t the specific interface between the inner and outer segments of photoreceptors.

IS/OS denotes the boundary between the photoreceptor inner segment and outer segment. The inner segment carries the cell’s metabolic machinery, while the outer segment contains the photopigment discs that actually detect light. On OCT this boundary appears as a distinct, bright line and is a key marker of photoreceptor integrity. If this junction is disrupted or poorly defined, it often correlates with reduced visual function. The other terms would describe broader regions (outer retina, sclera, surface tissues) that aren’t the specific interface between the inner and outer segments of photoreceptors.