Patent ID: 7819523

Claim:
A progressive multifocal contact lens having a distance portion for aiding a far vision, a near portion for aiding a near vision, and an intermediate portion in which a power is changed progressively between the distance portion and the near portion, in a lens optical region, so that said distance portion, said intermediate portion, and said near portion are arranged sequentially from one end to another end along a prescribed direction of said lens optical region; a power distribution of said lens optical region along said prescribed direction is set according to the following formula (1); and said prescribed direction is a vertical direction of an eye during wearing the progressive multifocal contact lens: [ Formula ⁢ ⁢ 1 ] PowerDist = P ⁢ - ⁢ Power + ( Max ⁢ - ⁢ Add π ) ⁢ { tan - 1 ⁡ ( Wave Bnf ⁢ X - Wave ) + tan - 1 ⁡ ( Wave ) } ( 1 ) wherein each symbol in the formula (1) is defined as follows: PowerDist: power distribution (unit: D (diopter)); P-Power: power (unit: D) at one end point of the lens optical region; Max-Add: power difference (unit: D) between one end point and the other end point of the lens optical region; Bnf: distance (unit: mm) from one end point of the lens optical region to a boundary between a distance power of the distance portion and a near power of the near portion; Wave: power variation coefficient (wave degree); and x: distance (unit: mm) from one end point of the lens optical region; wherein −25D≦P-Power≦+25D; ±0D≦Max-Add≦+8D; 0.5 mm≦Bnf≦7 mm; and 1≦Wave≦8.