Myopic astigmatism as a substitute for accommodation in pseudophakia.
Pseudophacic eyes can be made nearly spectacle-independent by increasing the depth of focus of the uncorrected implanted eye. When the postoperative ametropia is a simple myopic astigmatism the uncorrected visual acuity can be above 0.4 from far to near. The quasi-constant visual acuity in different distances is due to the slow change in the dimension of the blurred retinal image when a point source comes nearer to a myopic astigmatic eye. The intersection of Sturm's conoid and the retina (i.e. the blur spot) changes mainly in form but its size changes much less than in a sperical ametropia. To obtain such a refraction the dioptric change in corneal power induced by surgery must be included in the calculation of the intraocular lens. The induced corneal ametropia is a mixed astigmatism with no equivalent power. The optical principles and the clinical results obtained with iridocapsular Binkhorst lenses are discussed.
D000065:Accommodation, Ocular; D001251:Astigmatism / Q000150:complications*; D002387:Cataract Extraction / Q000379:methods; D006801:Humans; D007910:Lenses, Intraocular; D009216:Myopia / Q000150:complications*; D009799:Ocular Physiological Phenomena; D055095:Optics and Photonics; D011183:Postoperative Complications