The Laser MegaJoule (LMJ) is a 176-beamlines facility, located at CEA CESTA near Bordeaux (France). It is designed to deliver about 1.4 MJ of ultraviolet laser energy on targets set in vacuum chamber, for high energy density physics experiments, including fusion experiments. Final fused silica optics operating at the wavelength of 351 nm are the most exposed to laser damage. Among them, the vacuum window is particularly monitored. Optics damage limit lifetime and degrade focal spot performance. Moreover, for questions of manufacturability, ease of maintenance and cost, understanding and improvement of final optics laser damage resistance are of main importance. To extend lifespan of these optics, two main guidelines are being followed. The reduction of spatial and temporal laser beam modulations to preserve their weakened areas, and a recycle loop consisting in the removal of the optics to mitigate damage sites. This contribution will detail the effort conducted in these two following fieldsss: damage identification algorithm and optics lifetime models.