An apparatus includes a probe having a lumen and a first inflatable transparent balloon deployable through the lumen. The first balloon is coupled to be filled with liquid. The apparatus includes a second inflatable transparent balloon, deployable through the lumen, and disposed inside the first inflatable balloon between a proximal side and a distal side of the first inflatable balloon. The second balloon is coupled to be filled with air. The apparatus also includes a camera deployable through the lumen between a proximal side and a distal side of the second inflatable balloon and configured to capture an optical image formed through the first and second inflatable balloons.
