Short story - pick one with a high Dk/t :) Given that you have to go to a High Street optometrist to buy lenses, it helps to crosscheck their sales pitch a bit. Case in question is Specsavers offering me daily disposable varifocals, without indicating that the monthlies, though cheaper, are actually more breathable for my eyes. My conclusions from surfing: A contact lens needs to deliver a high level of oxygen to the cornea. Silicon hydrogel lenses are currently the best mix of oxygen permeability and comfort. Silicon lenses on their own allow oxygen to permeate but can stick to the cornea due to no water and leave deposits. Hydrogel lenses on their own have a high water content but as water changes the refractive index lenses needed are thicker,cutting off oxygen. Contact lenses are given a "Dk" value, where D is the diffusion and k the solubility of oxygen. A consistent comparison parameter is "Dk/t" which is oxygen passing through a lens in a specif