Ophthalmic blade with moveable section

An ophthalmic instrument, comprising:

• a blade extending in a horizontal plane along a central longitudinal axis and a lateral axis orthogonal to the longitudinal axis, the blade symmetric about the central longitudinal axis, wherein the blade comprises:
• an anterior blade portion having a triangular head and a shaft;
• the triangular head having opposed anterior cutting edges that extend from an anterior tip to a base position, the base position having a base width parallel with the lateral axis;
• the shaft having a shaft width between opposed shaft edges that is less than the base width, the shaft extending aft from the base position;
• a fixed blade portion having a forward lateral position with a forward width and a posterior lateral position with a posterior width that is greater than the forward width and opposed posterior cutting edges extending from the forward lateral position to the posterior lateral position;
• and
• a pocket formed in the fixed blade portion and extending aft along and bisected by the central longitudinal axis:
• wherein the shaft is positioned in the pocket and moveable between a retracted position with the base position located with the forward lateral position whereby the opposed anterior cutting edges and the opposed posterior cutting edges present substantially continuous cutting edges, and an extended position where the base position is spaced forward of the forward lateral position by an extension length.