there are hundreds of different pressure sensors. Go thru the literature and find the one that suits your requirements, as to pressure range, output range, size, atmosphere/fluid, etc. Then come back here with the specs of that sensor. A circuit can be designed with an opamp or comparator to drive a relay which will open the lens, assuming the lens can be electrically driven. And we need the specs on the lens drive also.
Also, is this an on/off circuit, when the pressure exceeds (or drops below) a set point, the lens is opened, and VV, or is it a proportional control?
For a university student, presumably in electronics, you are very sparse on the details. In this type of project, details are everything. You sit down and list the specs of the sensor, the lens, and what you want to do, and it all starts to come together.