A head-mounted display may include a display system and a lens system in a housing. The head-mounted display may include control circuitry that operates the head-mounted display in an active use mode and a protected mode. In the protected mode, the display system may be protected from collisions with the lens system. Placing the head-mounted display in the protected mode may include using an actuator to increase the distance between the display system and the lens system, may include injecting fluid between the display system and the lens system, and/or may include deploying a protective layer between the display system and the lens system. The control circuitry may determine whether to operate the head-mounted display in protected mode or active use mode based on sensor data, on/off status information, location information, and/or other information.