Richard S. Hoffman

Prospective randomized trial of an anterior surface modified prolate intraocular lens

PURPOSE We compare the contrast sensitivity obtained with an anterior surface modified prolate intraocular lens with the contrast sensitivity obtained with a standard spherical intraocular lens. METHODS Patients presenting for cataract surgery in one eye were randomized to receive either the Tecnis Z9000 intraocular lens (Pharmacia) or the AMO AR40e Opti-Edge intraocular lens (AMO). Sine wave grating contrast sensitivity testing under mesopic and photopic conditions served as the principal outcome measure. RESULTS The Tecnis Z9000 intraocular lens provided statistically significantly better contrast sensitivity at 1.5 and 3 cycles per degree under mesopic conditions and at 6, 12 and 18 cycles per degree under photopic conditions. CONCLUSION The use of a modified prolate intraocular lens during cataract surgery has the potential to improve contrast sensitivity under both mesopic and photopic conditions.

Improved functional vision with a modified prolate intraocular lens

Purpose: To evaluate whether the Tecnis Z9000 intraocular lens (IOL) (Pfizer) with a modified prolate anterior surface provides better quality of vision than a conventional spherical IOL. Setting: Oregon Eye Institute, Eugene, Oregon, USA. Methods: Patients presenting for cataract surgery who were randomly assigned to receive a Tecnis Z9000 IOL (Pfizer) or a Sensar® OptiEdge AR40e IOL (AMO) in 1 eye were followed for 3 months postoperatively. The patient could elect to have the same type of IOL implanted in the fellow eye. The results of sine‐wave grating contrast sensitivity testing under mesopic and photopic conditions were compared interindividually. Results: Monocular comparison was made between the 2 IOL groups, which comprised 15 patients each. The Tecnis IOL provided significantly better contrast sensitivity at 6 cycles per degree (cpd) under photopic conditions and at 1.5 and 3 cpd under mesopic conditions. Seven patients with a Tecnis IOL and 9 patients with an AR40e IOL had subsequent implantation in the fellow eye. In all eyes, including fellow eyes, having IOL implantation, the Tecnis provided significantly better contrast sensitivity at 3 and 6 cpd under photopic conditions and at 1.5, 3, and 6 cpd under mesopic conditions. The mean contrast sensitivity in fellow eyes showed that the Tecnis IOL produced significantly better results at some spatial frequencies. Conclusions: Results show the Tecnis IOL with a modified prolate anterior surface may produce better contrast sensitivity than a standard spherical IOL under mesopic and photopic conditions. Because contrast sensitivity testing correlates well with functional vision, a goal of future research should be to evaluate patient performance using functional tests such as driving simulation.

Immersion A-scan compared with partial coherence interferometry: Outcomes analysis

Purpose: To compare 2 methods of axial length measurement, immersion ultrasonography and partial coherence interferometry, and to elucidate surgical outcomes based on immersion measurements. Setting: Oregon Eye Institute, Eugene, Oregon, USA. Methods: Axial length measurements in 50 cataractous eyes were obtained by optical biometry (IOLMaster®, Zeiss Humphrey Systems) and immersion ultrasound (Axis II, Quantel Medical), and the results were compared. Intraocular lens (IOL) power calculations in the same eyes after cataract extraction and posterior chamber IOL implantation were evaluated retrospectively based on the postoperative spherical equivalent prediction error. Results: Immersion ultrasonography and partial coherence interferometry measurements correlated in a highly positive manner (correlation coefficient = 0.996). Outcomes analysis demonstrated 92.0% of eyes were within ±0.5 diopter of emmetropia based on immersion axial length measurements. Conclusion: Immersion ultrasonography provided highly accurate axial length measurements and permitted highly accurate IOL power calculations.

Clinical evaluation of the Crystalens AT-45 accommodating intraocular lens : Results of the U.S. Food and Drug Administration clinical trial

PURPOSE: To evaluate the 12‐month U.S. phase II clinical trial results of the Crystalens AT‐45 (eyeonics, Inc.) intraocular lens (IOL) used to provide uncorrected distance, intermediate, and near visual acuities in patients having cataract extraction and to compare in a substudy the contrast sensitivity and near visual acuity in patients with the Crystalens AT‐45 IOL and those receiving a standard IOL. SETTING: Fourteen clinical sites throughout the U.S. for efficacy and 3 non‐U.S. sites for safety and efficacy. METHODS: Patients 50 years or older had small‐incision cataract extraction with implantation of the Crystalens AT‐45 IOL. Unilateral implantation was followed by fellow‐eye implantation. Postoperatively, uncorrected distance, near, and intermediate visual acuities were determined. Near and intermediate visual acuities were tested through a distance correction to eliminate potential pseudoaccommodative effects of residual myopia and corneal cylinder. A substudy tested contrast sensitivity under mesopic conditions with and without glare, as well as visual acuity in a subset of Crystalens AT‐45 patients and a control group receiving a standard IOL. RESULTS: A total of 263 patients participated in the U.S. clinical trial and had 1 year of follow‐up. Near visual acuities through the distance correction of 20/40 (J3) or better, monocularly and bilaterally, respectively, were seen in 90.1% and 100%; intermediate near visual acuities were seen in 99.6% and 100%. More than half the bilaterally implanted Crystalens AT‐45 patients achieved uncorrected near acuity of 20/25 (J1) or better through the distance correction, and 84% achieved 20/32 (J2) or better. In the substudy, monocular near vision through the distance correction of 20/25 (J1) or better was seen in 50.4% with the Crystalens AT‐45 IOL and in 4.7% with the standard IOLs. Mesopic contrast sensitivity results with and without glare for the Crystalens AT‐45 were similar to those with standard monofocal IOLs. Nearly all patients (74 patients; 97.3%) who bilaterally were within 0.50 diopter of plano postoperatively achieved 20/32 (J2) or better uncorrected near, intermediate, and distance visual acuities. CONCLUSIONS: The Crystalens AT‐45 accommodating IOL provided good uncorrected near, intermediate, and distance vision in pseudophakic patients. Contrast sensitivity with the Crystalens AT‐45 was not diminished relative to standard monofocal IOLs, and near and intermediate visual performance was significantly better than with standard IOLs.

Profile of clear corneal cataract incisions demonstrated by ocular coherence tomography

PURPOSE: To examine the profile of clear corneal cataract incisions in the living eye using optical coherence tomography (OCT). SETTING: Private practice, Eugene, Oregon, USA. METHODS: The Zeiss Visante OCT anterior segment imaging system was used to study the profile of clear corneal cataract incisions, all in senior citizens. The OCT images of the operative eye were taken on the first postoperative day approximately 24 hours after surgery. The OCT images of clear corneal incisions were compared with an OCT image of a control eye, incisions without stromal hydration, and previous drawings of clear corneal incisions. RESULTS: In the images, the clear corneal incisions had an arcuate configuration rather than a straight line configuration, as previously indicated. This architecture appears to add greater stability as a result of a tongue‐and‐groove‐like fit of the floor to the roof of the incision as well as an incision that is longer than the chord length that had previously been measured. Other findings include that stromal swelling, which facilitates sealing of these incisions by the endothelial pump, lasted for at least 24 hours. CONCLUSIONS: Results indicate an incision in the plane of the cornea with a chord length of at least 2.0 mm provides advantageous architecture for adequate self‐sealing. Proper clear corneal incision construction resulted in an incision architecture that seemed to have increased stability and added safety, contributing to an absence of endophthalmitis for more than 10 years and 9000 cases in a single practice.

Use of power modulations in phacoemulsification: Choo-choo chop and flip phacoemulsification

&NA; We used power modulations in addition to new technology available from 6 phacoemulsification manufacturers and altered our phacoemulsification techniques to take advantage of these technologies to significantly reduce the amount of ultrasound energy placed into the eye and enhance the rapidity and level of visual rehabilitation in patients.

Power modulations in new phacoemulsification technology: Improved outcomes

Purpose: To evaluate the clinical outcomes of new phacoemulsification technology. Setting: Oregon Eye Institute, Eugene, Oregon, USA. Methods: After optimization of surgical parameters, patients were randomly assigned to cataract extraction with 1 of 4 phacoemulsification machines using new technology available within the past 1 to 2 years. Outcomes were compared with previously published results for these same machines obtained before the advent of the new technology. Results: Improvements in effective phaco time, average phaco power, percentage of clear corneas, and 20/40 or better uncorrected visual acuity at the first postoperative visit were noted for most systems using new technology. Conclusion: New phacoemulsification technology offers surgical advantages that translate into improved clinical outcomes.

The physics of phaco: A review

&NA; Despite its unparalleled success in the field of surgery, the precise mechanism of ultrasonic phacoemulsification cataract extraction remains controversial. We review the relevant peer‐reviewed literature on the subject of power generation and tip–tissue interactions to clarify the current status of our knowledge. We conclude that phacoemulsification most likely operates by a combination of mechanisms, including direct action of the vibrating tip against tissue and indirect cavitational effects. Surgeons will benefit from understanding the physical principles underlying phacoemulsification because they will be better able to evaluate the performance of various parameters and different machine settings.

Refractive lens exchange with the array multifocal intraocular lens

Purpose: To study the safety and efficacy of refractive lens exchange as a refractive surgery modality in the presbyopic population. Setting: Oregon Eye Institute, Eugene, Oregon, USA. Methods: This retrospective review of patient charts included patient selection, preoperative evaluation, management of astigmatism, surgical technique, postoperative visual outcome, and complications. The study included 68 eyes comprising 32 bilateral and 4 unilateral refractive lens exchanges. Results: All patients having bilateral refractive lens exchange achieved an uncorrected binocular visual acuity of 20/40 and J5 or better 1 to 3 months postoperatively. More than 90% achieved an uncorrected binocular visual acuity of 20/30 and J4 and nearly 60%, of 20/25 and J3. Conclusion: Refractive lens exchange was a safe and effective refractive surgery modality in presbyopic patients.

New phacoemulsification technologies

&NA; To examine recent developments in the field of phacoemulsification, a literature review was conducted for each system described. the review included peer‐ reviewed articles, information from manufacturers, and meeting presentations by surgeons. our personal experience with systems we have used forms the underlying basis of our evaluation. data for erbium: YAG laser phacoemulsification came from an interim summary of the U.S. Food and Drug Administration monitored study. Data for NeoSoniX came from a prospective evaluation of phacoemulsification in 25 eyes performed at the Oregon Eye Surgery Center. The development of new technology has allowed safer, more efficient phacoemulsification. Each surgeon should evaluate new developments to achieve the greatest possible benefit for patients.