Cataracts are cloudy areas that develop within the eye lens. A healthy lens is clear like a camera's, and light has no problem passing through it to the retina at the back where images are processed. When you have a cataract, the light can't get through as easily and, as a result, you can't see as well. Cataracts often form slowly, and they don't cause symptoms like pain, redness, or tearing in the eye. Some stay small and don't affect your eyesight.
A composite flight plan is actually two flight plans-one VFR and one IFR. What makes it composite is that you will transition from one to the other at some specified point during your flight.
A synthetic vision system overlays relevant terrain information on the symbology of a primary flight display. The most advanced SVS PFDs use HUD symbology in place of the conventional pitch based PFD symbology to give the pilot a view into the energy state of the aircraft compared to the terrain it is overflying.