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Purpose: To use optical modeling to compare a 6.0 mm and 7.0 mm intraocular lens (IOL) optic diameters on peripheral retinal illumination with implications for negative dysphotopsia. Setting: Mayo Clinic, Rochester, Minnesota, and Simpson Optics LLC, Arlington, Texas. Design: Model eye. Methods: Ray-tracing software was used to simulate retinal illumination from an extended light source for a pseudophakic eye with in-the-bag biconvex IOLs (refractive index [n] = 1.46 and 1.55) and a 2.5 mm pupil. Ray-tracing diagrams and simulated retina illumination profiles were compared using the 6.0 mm and 7.0 mm optic diameter IOLs. Retinal locations were scaled to relative visual angles from 70 to 110 degrees horizontally. Results: A 7.0 mm optic (n = 1.46) expands the image field by 2.8 degrees compared with a 6.0 mm optic. High-angle input light misses a 7.0 mmoptic at a larger visual angle than a 6.0 mm optic, shifting illumination of the peripheral retina by this light anteriorly by 5.6 degrees. Consequently, a region of nonilluminated peripheral nasal retina is enlarged and shifted peripherally using a 7.0 mm optic (visual angle, 86.3 to 96.3 degrees) compared with a 6.0 mm optic (visual angle, 83.5 to 90.7 degrees). Similar illumination changes were seen modeling a 1.55 n IOL. Conclusions: A narrow dark region in the nasal retina when using a 6.0 mm optic is changed to a broader, more peripheral dark region when using a 7.0 mm optic. An extended, more peripheral dark nasal region may make a temporal shadow less bothersome and explain lower negative dysphotopsia rates using a 7.0 mm optic. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate negative dysphotopsia in the far periphery of the pseudophakic eye by generating simulated images of text charts. Setting: Consultancy. Design: Laboratory study. Methods: Simulated images of a peripheral text chart were created using a ray-trace model of a pseudophakic eye. The point spread function varies strongly with a radial location. Retinal angles subtended at the second nodal point were used to linearly scale retinal locations to a polar plot in object space, weighting rays by the object luminance, the total transmittance, and a cosine normalization for pupil effects. Improved scaling using a phakic 70-year-old eye was also explored. Results: Images demonstrate a distinct shadow with a 2.5 mm pupil between the upper limit of the text image formed by the intraocular lens (IOL) and a second larger image due to light missing the IOL. The shadow is rapidly softened by a small increase in pupil diameter. Conclusions: The images verified characteristics that previously were only inferred indirectly: (1) With a 2.5 mm pupil, there is a prominent dark shadow. (2) Light missing the IOL experiences lower power and forms a larger image and also comes from a lower visual angle. (3) A small increase in pupil diameter causes the shadow to fade. The calculations showed that imaging in the far periphery is very different for the pseudophakic eye in comparison with the phakic eye. The limit of the focused image is probably the primary cause of the shadow, yet relatively few patients find this to be bothersome. [ABSTRACT FROM AUTHOR]

Purpose: To report normative angle alpha orientation and magnitude distribution in a cataract surgery patient population. Setting: U.S. academic medical center. Design: Retrospective review. Methods: A total of 11 871 wavefront aberrometer/corneal topographer angle alpha measurements were performed over 40 months, yielding 8773 bilateral measurements (73.9%) with zero bad wavefront datapoints. The analysis was limited to the first right-eye scan for 3382 unique patients. The angle alpha magnitudes (millimeters) and orientations (degrees) were analyzed for these unique right eyes. Results: For the 3,382 unique patients, the mean angle alpha magnitude was 0.44 +/- 0.15 mm (median, 0.44 mm; 25th and 75th percentiles 0.34 mm, 0.53 mm). Angle alpha orientation was predominantly horizontal (P <.01), with a mean of 186 +/- 32 degrees. The expected point of intraocular lens (IOL) centration (EPIC) based on the geometric center of the corneal limbus was temporal to the visual axis in 3212 eyes (95%), nasal in 92 eyes (2.7%), inferior in 56 eyes (1.7%), and superior in 22 eyes (0.6%). The mean angle alpha magnitude was 0.3 mm or less in 607 eyes (18%) and 0.5 mm or greater in 1089 eyes (32%). Conclusions: Angle alpha is a predominantly horizontal phenomenon with a mean EPIC of 0.44 mm temporal to the visual axis. This information may assist in determining eligibility for patients in multifocal IOL implantation. [ABSTRACT FROM AUTHOR]

The ReSTOR intraocular lens presents a unique apodized diffractive design within a refractive foldable acrylic optic, which makes an unprecedented level of mulifocal optical performance available. We describe the history and principles of diffractive optics used in the development of this refractive–diffractive IOL. [Copyright &y& Elsevier]