Cataract Surgery with a Refractive Corneal Inlay in Place.

Purpose. To present a case of cataract surgery performed in a patient with a refractive corneal inlay in place. Methods. A 48-year-old female patient presented to our institute with bilateral cataract. The patient had undergone refractive corneal inlay implantation three years ago in her right, nondominant eye for presbyopia correction. Biometry and intraocular lens (IOL) power calculation were performed without removing the inlay. Phacoemulsification and IOL insertion were carried out in both eyes in a usual manner. Results. On day one postoperatively, the patient achieved binocular uncorrected distance visual acuity 20/20 and uncorrected near visual acuity J1. The vision remained stable during the one-year follow-up period. Conclusion. Cataract surgery was performed in a standard manner in a patient with Presbia Microlens corneal inlay in place. Visual outcomes for both near and distance vision were satisfactory.

Wavefront customized ablations with the WASCA Asclepion workstation.

PURPOSE: WASCA (Wavefront Aberration Supported Cornea Ablation) is a method for wavefront-guided ablation. This new method records all existing eye aberrations with the Asclepion Wavefront Aberrometer and calculates the customized pattern for laser correction. We measured the low and high order aberrations of eyes before and after PRK and LASIK, as well as before and after flap creation. METHODS: The Asclepion Shack-Hartmann aberrometer was used to measure wavefront aberrations. Preoperative and postoperative measurements were made following both PRK and LASIK performed with conventional software, modified Aberration-free Profile (AFA) software, and specially designed WASCA software. Surgery was performed with the Meditec MEL-70 G-scan excimer laser. Additionally, measurements were made before and after flap creation only (10 eyes). RESULTS: There was a significant difference between preoperative and 1-month postoperative high order aberrations, with notable increases following conventional PRK and LASIK and less increase following modified AFA PRK and LASIK. Flap creation only changed the higher order aberrations slightly, and caused a shift toward hyperopia. In the eyes that received WASCA correction with PRK or LASIK, at 3 months postoperative the high order aberrations averaged an increase of 1.3 times for PRK and 1.8 times for LASIK. Both the AFA and WASCA treatments demonstrated improved outcomes in comparison to conventional PRK and LASIK. CONCLUSION: Wavefront mapping of the eye and wavefront-guided ablation with the Asclepion Aberrometer can be used for optimizing the results and fine-tuning visual performance after laser vision correction. WASCA PRK appeared to result in better outcomes than WASCA LASIK.

Objective measurement of wavefront aberrations with and without accommodation.

PURPOSE: The measurement of the refractive error profile is more useful than corneal topography in understanding the complexities of refractive surgery. We report on experimental studies of the spatially resolved refractometer Tracey-1, developed in Ukraine by IBME in medical cooperation with VEIC, Greece. METHODS: Ten eyes were subjected to dynamic measurement of accommodation, in order to test the effectiveness of Tracey refractometry. Measurements were performed in zones 0 to 6 mm. The refractive aberrations were calculated and accommodation was evaluated. RESULTS: Evaluation of data shows that the instrument can effectively follow the dynamic change of refractive aberrations through the accommodation process. CONCLUSION: Clinical tests of Tracey technology demonstrated the ability to investigate accommodation using this instrument.

Principles of ray tracing aberrometry.

PURPOSE: Of all transforms of an eye, aberrations are significant when higher visual acuity is to be achieved. Ray tracing aberrometry developed by the Institute of Biomedical Engineering (Kiev) and first tested at the Vardinoyannion Eye Institute of Crete is a promising technique for eye refraction aberration and refraction mapping. METHODS: The technique uses measurement of the position of a thin laser beam projected onto the retina. The beam is directed into the eye parallel to the visual axis. Each entrance point provides its own projection on the retina. A set of entrance points forms a set of projections. From these data, a refraction map is reconstructed as well as a point spread function of the eye. The total time of scanning over the whole aperture of the eye is within 10 to 20 ms and depends on the number of test points at the eye entrance, as well as on the number of independent measurements in each point. Configuration of the scanning pattern can be chosen by the operator. It may contain 60 to 400 points, each checked 1 to 5 times. RESULTS: Preliminary studies showed high reproducibility of results. Twenty pseudophakic eyes were subjected to 30 consecutive measurements each. Ninety-five percent of all measured values were within +/-0.20 D of declination from the mean. CONCLUSIONS: Ray tracing aberrometry is a flexible technology for eye investigation. It can be adapted to any laser technique of vision correction Its further development should be oriented on laser-linked applications of the refraction driven refractive surgery.

Clinical experience with the Tracey technology wavefront device.

PURPOSE: In refractive surgery, measuring the total ocular profile of refraction gives more vital information than measuring the cornea alone. We report the first clinical experiments with spatially resolved refractometry using ray tracking principles. Tracey technology was developed in Ukraine by the Institute of Biomedical Engineering in cooperation with the Vardinoyannion Eye Institute of Crete. METHODS: The Tracey-1 device was evaluated in comparison with conventional videokeratoscopes. Seven pseudophakic eyes of 7 patients and two phakic eyes were measured thirty (30) consecutive times (consecutively) each to test reproducibility. Measurements were provided in zones 0 to 5 (6) mm. For each zone, parameters of astigmatism were calculated and mean value and standard deviation were derived. RESULTS: Standard deviation on the order of 0.14 D was derived. CONCLUSION: The Tracey Technology wavefront device provides information on the refraction distribution at the first principal plane of the ocular optical system. For the instrument to provide measurements that are directly applicable to clinical practice, the data should be transposed to the corneal plane. The Tracey device can be utilized for the measurement of accommodative amplitude and range. Further development of the instrument is requred to increase its accuracy.