There is disclosed a trephine guide having an upper guide member having a first substantially circular guide aperture and a first circumferential portion and a lower guide member having a second substantially circular guide aperture and a second circumferential portion. The upper and lower guide members are connected in a spaced apart configuration by at least one arm extending from the first circumferential portion to the second circumferential portion, such that the first and second guide apertures are substantially concentric, thereby to allow a trephine to pass through the upper and lower guide members. The at least one arm has a width that extends over less than three quarters of the circumference of the first or second circumferential portions to allow good visibility to a trephine blade.
