The effect of modifying oxides Nb 2 O 5, BaO, Ga 2 O 3, TiO 2 < / sub> on the glass-forming ability, thermal, physical and optical properties of glasses of the four-component system La 2 O 3 & # 8211; Al 2 O 3 & # 8211; B 2 O 3 & # 8211; SiO 2 (LABS). It was found that when modifying the LABS system, it is possible to achieve high values ??of the refractive index (n D = 1.81) in combination with low crystallization ability and the possibility of obtaining optically uniform glass castings up to 150 mm in size. The variety of coordination states of modifier cations determines their complex effect on the properties of glasses and the appearance of non-monotonic concentration dependences of properties. Synthesis of multicomponent glass in a 300 ml crucible using optical glass-making methods confirms the promising nature of this composition for its implementation on an industrial scale.