Non-corrective unitary lens eyeglasses or safety helmet comprising - a one-piece shield (300, 400), said shield (300, 400) having a front surface (302, 402) and a back surface (304, 404), whereby said front surface (302, 402) having a front surface geometry and said back surface (304, 404) having a back surface geometry; - a frame in which said one-piece shield is mounted or which forms a integral part of said shield; said frame being constructed to dispose said one-piece shield (300, 400) in a predetermined local relationship with respect to a wearer's head and eyes, whereby said wearer's head being one of a plurality of standardized head models of the group consisting of a head model having the Alderson headform, a head model having the headform according to EN 168, a head model having the headform according to ISO 12311:2013, a head model having the headform according to ISO 12312-1 and a head model having the Canadian headform; whereby said standardized head models each having left and right eyes being located at standardized positions thereby providing respective standardized theoretical centers of rotation of said left and right eyes, respective standardized theoretical monocular pupil distances and respective standardized "normal" lines of sight; - said one-piece shield (300, 400) being disposed in said predetermined local relationship with respect to said wearer's head and eyes establishing non-zero minus power and prism as worn of less than 0.15 prism diopter within a portion (307a, 307b, 407a, 407b) of said back surface (304, 404) surrounding an intersection of wearer's standardized "normal" line of sight of one of said wearer's eyes with said back surface (304, 404) for all of wearer's lines of sight intersecting said back surface within said portion (307a, 307b, 407a, 407b) due to eye rotations of said one of said wearer's eyes around said respective standardized theoretical center of rotation of said one of said wearer's eyes, whereby said non-zero minus power within said portion (307a, 307b, 407a, 407b) being less than 0.12 D, whereby said portion (307a, 307b, 407a, 407b) being larger than 0.1 cm 2, whereby said portion (307a, 307b, 407a, 407b) of said back surface (304, 404) having a freeform surface geometry, and, whereby said freeform surface geometry has no symmetry over an area and whereby said front surface (302, 402) is curved in horizontal direction between the point where the "normal" straight ahead line of sight of the wearer's left eye intersects the front surface (302, 402) and the point where the "normal" straight ahead line of sight of the wearer's right eye intersects the front surface (302, 402) without having any kink or change of direction of curvature. - a one-piece shield (300, 400), said shield (300, 400) having a front surface (302, 402) and a back surface (304, 404), whereby said front surface (302, 402) having a front surface geometry and said back surface (304, 404) having a back surface geometry; - a frame in which said one-piece shield is mounted or which forms a integral part of said shield; said frame being constructed to dispose said one-piece shield (300, 400) in a predetermined local relationship with respect to a wearer's head and eyes, whereby said wearer's head being one of a plurality of standardized head models of the group consisting of a head model having the Alderson headform, a head model having the headform according to EN 168, a head model having the headform according to ISO 12311:2013, a head model having the headform according to ISO 12312-1 and a head model having the Canadian headform; whereby said standardized head models each having left and right eyes being located at standardized positions thereby providing respective standardized theoretical centers of rotation of said left and right eyes, respective standardized theoretical monocular pupil distances and respective standardized "normal" lines of sight; - said one-piece shield (300, 400) being disposed in said predetermined local relationship with respect to said wearer's head and eyes establishing non-zero minus power and prism as worn of less than 0.15 prism diopter within a portion (307a, 307b, 407a, 407b) of said back surface (304, 404) surrounding an intersection of wearer's standardized "normal" line of sight of one of said wearer's eyes with said back surface (304, 404) for all of wearer's lines of sight intersecting said back surface within said portion (307a, 307b, 407a, 407b) due to eye rotations of said one of said wearer's eyes around said respective standardized theoretical center of rotation of said one of said wearer's eyes, whereby said non-zero minus power within said portion (307a, 307b, 407a, 407b) being less than 0.12 D, whereby said portion (307a, 307b, 407a, 407b) being larger than 0.1 cm 2, whereby said portion (307a, 307b, 407a, 407b) of said back surface (304, 404) having a freeform surface geometry, and, whereby said freeform surface geometry has no symmetry over an area and whereby said front surface (302, 402) is curved in horizontal direction between the point where the "normal" straight ahead line of sight of the wearer's left eye intersects the front surface (302, 402) and the point where the "normal" straight ahead line of sight of the wearer's right eye intersects the front surface (302, 402) without having any kink or change of direction of curvature.