Patent ID: 8079706

Claim:
An apparatus for aligning a mask with a visual axis of an eye of a patient, the apparatus comprising: a first target positioned on an instrument axis at a first distance relative to a first location; a second target positioned on the instrument axis at a second distance relative to the first location; and a marker configured to indicate the location of the instrument axis; wherein the mask comprises an aperture having a mask axis that can be positioned substantially collinear with the instrument axis, further wherein the mask comprises an annulus configured to be substantially opaque to visible light and to extend between the aperture and an outer periphery of the mask, the annulus having an inner peripheral region between a central region and the aperture and an outer peripheral region between the central region and the outer periphery of the mask, the inner peripheral, central and outer peripheral regions each having a nutrient transport structure for conveying nutrients between anterior and posterior surfaces of the mask, the nutrient transport structure providing an amount of open area per unit area in the central region that is greater than an amount of open area per unit area in at least one of the outer peripheral region and the inner peripheral region.