Contributes to the transparency and refractive index of the lens. Acts as a chaperone, preventing aggregation of various proteins under a wide range of stress conditions. Required for the correct formation of lens intermediate filaments as part of a complex composed of BFSP1, BFSP2 and CRYAA. Heteropolymer composed of three CRYAA and one CRYAB subunits. Inter-subunit bridging via zinc ions enhances stability, which is crucial as there is no protein turn over in the lens. Can also form homodimers and homotetramers (dimers of dimers) which serve as the building blocks of homooligomers (By similarity). Within homooligomers, the zinc-binding motif is created from residues of 3 different molecules. His-123 and Glu-125 from one molecule are ligands of the zinc ion, and His-130 and His-177 residues from additional molecules complete the site with tetrahedral coordination geometry (By similarity). Part of a complex required for lens intermediate filament formation composed of BFSP1, BFSP2 and CRYAA (By similarity). Translocates to the nucleus during heat shock and resides in sub-nuclear structures known as SC35 speckles or nuclear splicing speckles. Acetylation at Lys-93 may increase chaperone activity. Undergoes age-dependent proteolytical cleavage at the C-terminus. Constitutes approximately 10% of the total alpha-A-crystallin in the lens. Belongs to the small heat shock protein (HSP20) family.