A variable focus optical apparatus including a rigid, curved, transparent optical component; two transparent, distensible membranes attached to a periphery of the rigid optical component to define two cavities, a first cavity between the rigid optical component and a first membrane and a second cavity between the first membrane and a second membrane; and a variable amount of fluid filling each of the cavities, and a reservoir containing additional fluid and in fluid communication with the cavity, wherein the reservoir is configured to provide injection of fluid into the cavity or withdrawal of fluid out of the cavity in response to a force or an impulse.