For the biomaterials scientist, the eye presents unique problems, principally because the maintenance of optical function is paramount. This paper concentrates on some current challenges in the development of devices to be placed in the optical path: from air to tear film, cornea, aqueous humour, pupil, lens, vitreous humour, and finally to the retina. Optical clarity during contact lens wear depends on control of deposits from tear film components (by patient performed cleaning procedures) and on continuous oxygen supply to the cornea whose clarity depends on intact epithelial and endothelial cells. Intracorneal lenses of contact lens material are possible if intracorneal fluid flow is not compromised. Corneal integrity can also be affected by adhesive endothelial cell damage during intraocular lens implantation, a factor leading to the development of so-called visco-elastic media for anterior chamber use. The associated questions of photodegradation of materials and protection of the optical tissues from photo-toxicity are critical in the eye. Laser surgery is also uniquely valuable in ophthalmology since many procedures can be performed without invasive access. Finally, intraocular lenses can also incur protein adsorption, cellular adhesion, and opacification of the lens capsule which compromise optical performance.