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Purpose: To design and validate a new miniaturized open-field wavefront device that can be attached to an ophthalmic surgical microscope or slitlamp. Setting: Solihull Hospital and Aston University, Birmingham, United Kingdom. Design: Comparative noninterventional study. Methods: The dynamic range of the Aston aberrometer was assessed using a calibrated model eye. The validity was compared with that of a conventional desk-mounted Hartmann-Shack aberrometer (Topcon KR1W) in dilated eyes. The instruments were used in random order, with measurements repeated 5 times to assess intrasession repeatability. Results: The open-field aberrometer had a large dynamic range of at least +21.0 diopters (D) to −25.0 D. It gave similar measurements to the conventional aberrometer for mean spherical equivalent (SE) (mean difference 0.02 D ± 0.49 [95% confidence interval]; correlation r = 0.995; P<.001), astigmatic components (J0: 0.02 ± 0.15 D; r = 0.977, P<.001; J45: 0.03 ± 0.28, r = 0.666, P<.001), and higher-order aberration (HOA) root mean square (RMS) (0.02 ± 0.20 D, r = 0.620, P<.001). Intraclass correlation coefficient assessments of intrasession repeatability were excellent (SE = 1.000, P<.001; J0 = 0.998, P<.001; J45 = 0.980, P<.01; HOA RMS = 0.961, P<.001). Conclusions: The new aberrometer gave valid, repeatable measurements of refractive error and HOAs over a large range. It can measure continuously, thus providing direct feedback on the optical status of the visual system to surgeons during intraocular lens implantation and corneal surgery. Financial Disclosure: The Aston aberrometer is jointly patented by Topcon Corp. and Prof. Wolffsohn. Drs. Mihashi and Yamaguchi are employees of Topcon Corp., Tokyo, Japan. No other author has a financial or proprietary interest in any material or method mentioned. [ABSTRACT FROM AUTHOR]

For the transmission electron aberration-corrected microscope (TEAM) initiative of five U.S. Department of Energy laboratories in the United States, a correction system for the simultaneous compensation of the primary axial aberrations, the spherical aberration Cs , and the chromatic aberration Cc has been developed and successfully installed. The performance of the resulting Cc /Cs-corrected TEAM instrument has been investigated thoroughly. A significant improvement of the linear contrast transfer can be demonstrated. The information about the instrument one obtains using Young's fringe method is compared for uncorrected, Cs-corrected, and Cc /Cs-corrected instruments. The experimental results agree well with simulations. The conclusions might be useful to others in understanding the process of image formation in a Cc /Cs-corrected transmission electron microscope. [ABSTRACT FROM AUTHOR]

Purpose: To compare the ocular wavefront aberration between pharmacologically- and stimulus-driven accommodation in phakic eyes of young subjects. Methods: The aberration structure of the tested eye when accommodating was measured using the Complete Ophthalmic Analysis System (COAS; AMO WaveFront Sciences, Albuquerque, NM, USA). It was used in conjunction with a purposely-modified Badal optometer to allow blur-driven accommodation to be stimulated by a high contrast letter E with a vergence range between +0.84 D and −8.00 D. Pharmacological accommodation was induced with one drop of pilocarpine 4%. Data from six subjects (age range: 23–36 years) with dark irides were collected. Results: No correlation was found between the maximal levels of accommodative response achieved with an 8 D blur-driven stimulus and pharmacological stimulation. Pharmacological accommodation varied considerably among subjects: maximum accommodation, achieved within 38–85 min following application of pilocarpine, ranged from 2.7 D to 10.0 D. Furthermore, although the changes of spherical aberation and coma as a function of accommodation were indistinguishable between the two methods for low levels of response, a characteristic break in the pattern of aberration occurred at higher levels of pilocarpine-induced accommodation. This probably resulted from differences in the time course of biometric changes occuring with the two methods. Conclusion: Measuring the pilocarpine-induced accommodative response at only one time point after its application may lead to misleading results. The considerable inter-individual differences in the time course of drug-induced accommodative response and its magnitude may lead to overestimation or underestimation of the corresponding amplitude of normal, blur-driven accommodation. Stimulating accommodation by topical application of pilocarpine is inappropriate for evaluating the efficacy of ‘accommodating’ IOLs. [ABSTRACT FROM AUTHOR]

Evaluates the production and analysis of injection molded micro-optic components in the U.S. Inclusion of small-scale phenomena; Average difference between simulation and experiment for astigmatism and comatic aberration; Comparison of the predicted values.

PURPOSE: Manufacturers of refractive surgical lasers are seeking Food and Drug Administration (FDA) approval for refractive surgery based on wavefront measurements rather than manifest refractions. This article draws attention to the need for better understanding of the relationship between aberrations and visual function and better testing methods for evaluating safety and effectiveness of wavefront-guided refractive surgery. METHODS: Before U.S. market approval for a new medical device, the FDA must determine whether the manufacturer has provided reasonable assurance that the device is safe and effective for its intended use, based on valid scientific evidence. The issues discussed here are based on FDA reviewers' experiences in evaluating Investigational Device Exemption (IDE) and Premarket Approval (PMA) applications for wavefront-guided refractive lasers. RESULTS: Even an optimal wavefront correction can provide only a marginally greater visual function benefit than a conventional spherocylindrical correction in a normal eye. Actual benefits are even smaller or nonexistent because variability from uncontrollable sources (eg, healing, aging, accommodation, pupil size, or ocular biomechanical effects) are typically larger than the errors treated. The effects of higher order aberrations and aberration changes on visual function are complex and poorly understood. CONCLUSIONS: The FDA's need for better tools to assess safety and effectiveness of wavefront-guided refractive surgery has stimulated major research efforts within the vision, ophthalmic, and optometric research communities. More research is needed to better understand the relationship between aberrations and visual function, and to be able to predict the visual effects of specific aberration changes in individual eyes. This research would have been more appropriately done before rather than after clinical trials for wavefront-guided refractive lasers. [ABSTRACT FROM AUTHOR]