Understanding interparticle interactions in protein solutions is of central importance to gain insight into the origin of protein condensation diseases. While the study of such condensation diseases has traditionally focussed on a molecular view point based on specific, detailed properties of the molecules involved, considerable progress has also been made using statistical and colloid physics, in which the formation of condensed protein phases can be quantitatively analyzed in terms of a subtle interplay between interprotein attractions, repulsions, and entropy. The analogy between colloids and proteins has not only been driven by biological and biomedical research. Globular proteins have also drawn great attention in the colloid physics community due to their suitability as model colloids. Here we demonstrate the importance of this approach for the lens crystallin proteins, which are vital for eye lens transparency and for understanding cataract, a clouding of the eye lens due to increased light scattering. By combining small-angle neutron scattering (SANS) experiments and molecular dynamics (MD) computer simulations, we demonstrate that transparency of lens crystallin protein mixtures at high concentrations, comparable to those in the living eye lens, is greatly enhanced by weak, short-range attractions between two of the prevalent mammalian crystallins, alpha- and gamma-crystallin. Provided they are not too strong, such mutual attractions considerably decrease the critical temperature and corresponding opacity due to light scattering, and are thus essential for lens transparency.