A ray tracing approach to calculate toric intraocular lenses.

PURPOSE: To quantify the precision of astigmatic correction in routine cataract surgery with toric intraocular lenses (IOLs) and to evaluate the predictability of keratometric and anterior/posterior topographic measurement for the improvement of the overall accuracy. METHODS: Seventy-eight eyes of 56 patients were implanted with toric IOLs. Data acquired by the Lenstar optical biometer (Haag-Streit, Bern, Switzerland) and TMS5 topography (Tomey, Nagoya, Japan) were processed with the ray tracing software Okulix (Tedics, Dortmund, Germany) to predict the residual refraction. Four different inputs were examined: keratometry only, anterior topography, anterior and posterior topography/ tomography, and combination of keratometry only and anterior and posterior topography/tomography. Four weeks postoperatively, the spherical prediction error and the cylindrical prediction error (difference vector between predicted and achieved cylindrical refraction) were determined. RESULTS: Mean absolute error of spherical prediction error was 0.27 diopter (D). Cylindrical prediction errors were 0.57 D (keratometry only), 0.56 D (anterior topography), 0.56 D (anterior and posterior topography/ tomography), and 0.50 D (combination of keratometry only and anterior and posterior topography/tomography). Differences between intraocular lens groups were statistically significant (Friedman test, P < .05). CONCLUSION: The combination of keratometry and anterior and posterior topography/tomography of anterior and posterior surface yielded the best results for toric IOL power calculations.

Clinical outcomes after implantation of a new hydrophobic acrylic toric IOL during routine cataract surgery.

PURPOSE: To assess the clinical outcomes after implantation of a new hydrophobic acrylic toric intraocular lens (IOL) to correct preexisting corneal astigmatism in patients having routine cataract surgery. SETTING: Four hospital eye clinics throughout Europe. DESIGN: Cohort study. METHODS: This study included eyes with at least 0.75 diopter (D) of preexisting corneal astigmatism having routine cataract surgery. Phacoemulsification was performed followed by insertion and alignment of a Tecnis toric IOL. Patients were examined 4 to 8 weeks postoperatively; uncorrected distance visual acuity (UDVA), corrected distance visual acuity, manifest refraction, and keratometry were measured. Individual patient satisfaction with uncorrected vision and the surgeon's assessment of ease of handling and performance of the IOL were also documented. The cylinder axis of the toric IOL was determined by dilated slitlamp examination. RESULTS: The study enrolled 67 eyes of 60 patients. Four to 8 weeks postoperatively, the mean UDVA was 0.15 logMAR ± 0.17 (SD) and the UDVA was 20/40 or better in 88% of eyes. The mean refractive cylinder decreased significantly postoperatively, from -1.91 ± 1.07 D to -0.67 ± 0.54 D. No significant change in keratometric cylinder was observed. The mean absolute IOL misalignment from the intended axis was 3.4 degrees (range 0 to 12 degrees). The good UDVA resulted in high levels of patient satisfaction. CONCLUSION: Implantation of the new toric IOL was an effective, safe, and predictable method to manage corneal astigmatism in patients having routine cataract surgery.

Comparison of visual performance of silicone and acrylic multifocal IOLs utilizing the same diffractive design.

PURPOSE: To compare the visual outcomes in patients implanted with a diffractive silicone multifocal in one eye and a diffractive acrylic multifocal IOL in their fellow eye. SETTING: Augenklinik, Bad Hersfeld, Germany. METHODS: Forty-two eyes of 21 cataract surgery patients were randomized to undergo implantation with either a silicone diffractive multifocal IOL (Tecnis ZM900, Abbott Medical Optics, Santa Ana, CA, USA) or an acrylic diffractive multifocal IOL (Tecnis ZMA00, AMO). The two IOLs share the same design platform. Outcome measurements included uncorrected and best-corrected distance and near visual acuity, spherical equivalent, reading speed and reading acuity, as well as photic phenomena. Patients were followed for 6 months following surgery. RESULTS: The mean spherical equivalent was 0.161 D (acrylic) and 0.065 D (silicone). The mean uncorrected visual acuity was 0.17 logMAR for the acrylic eyes and 0.17 logMAR for the silicone eyes, a difference of 0.01 (p=0.861). The mean best-corrected visual acuity (BCVA) was 0.08 for the acrylic eyes and 0.10 for the silicone lens, a difference of 0.03 (p=0.321). CONCLUSIONS: Given that the designs of the lenses are identical and that this was a contralateral eye study, it is reasonable to expect that the results between the two eyes and two types of lenses were similar. Both versions of this lens provide excellent visual function.

Corneal responses to eye rubbing with spectral domain optical coherence tomography.

PURPOSE: Surprisingly, a significant reduction (18.4%) in epithelial thickness was found after 15 seconds of eye rubbing measured using Holden-Payor optical pachometer reported in the literature. Hence, we aimed at studying the effects of compressive and shearing pressure associated with eye rubbing on total corneal, epithelial and Bowman's membrane thickness using spectral domain OCT (SD-OCT). METHODS: SD-OCT (Spectralis; Heidelberg Engineering) was used to acquire cross-sectional images of the cornea. Central total-corneal thickness (TCT), epithelial thickness (ET) and Bowman's membrane thickness (BMT) was measured on 20 eyes of 10 subjects with normal corneas without any ocular pathology using in-house developed MATLAB (Mathworks, Inc.) program. Two different measurement methods (distance between inflection points and peak to peak distance) were performed on luminance graph to obtain thickness profile of the corneas. Baseline measurements were compared with the measurements obtained immediately after 30 seconds of circular eye rubbing over the closed eye lid with contra lateral eye at a primary gaze position. RESULTS: We have found that the mean difference in TCT, ET and BMT to be 0.44 ± 6.00 µm, 0.28 ± 1.72 µm, and 0.01 ± 0.77 µm with first method of measurement, respectively, and the mean difference in TCT and ET were -0.26 ± 5.75 µm, and 0.37 ± 1.38 µm with second method of measurement respectively before and after eye rubbing. These differences were statistically insignificant (all p > 0.05) using both measuring methods. CONCLUSION: Thirty seconds of circular pattern rubbing over closed eye lids using index finger produce no significant changes on total corneal, epithelial and Bowman's membrane thickness.

Evaluation of corneal endothelial cell loss and corneal thickness after cataract removal with light-adjustable intraocular lens implantation: 12-month follow-up.

PURPOSE: To determine quantitative changes in endothelial cell loss and corneal thickness in patients having cataract surgery and implantation of a light-adjustable intraocular lens (IOL) to correct residual postoperative refractive errors by application of a spatially profiled near-ultraviolet (UV) light. SETTING: Ruhr University Eye Clinic, Bochum, Germany. DESIGN: Cohort study. METHODS: The light-adjustable IOLs were implanted after phacoemulsification cataract surgery and treated with spatial-intensity-profiled UV light at 365 nm to induce a targeted refractive change. Once the desired correction was achieved, the light-adjustable IOL was treated again to lock-in the lens power. Noncontact computer-assisted endothelial cell microscopy and corneal pachymetry were performed before surgery; after surgery before adjustment; before lock-in; and 1, 3, 6, and 12 months after final lock-in. RESULTS: One hundred twenty-two eyes were evaluated 12 months after lock-in. The mean cumulative UV light dose at the cornea was 61.47 J/cm(2) ± 2.37 (SD). The mean endothelial cell loss was 6.91% ± 3.66% 2 weeks after surgery before adjustment and 6.57% ± 3.81% 12 months after lock-in. The mean relative change in corneal thickness from preoperatively was 6.18% ± 3.97% 2 weeks postoperatively and -0.64% ± 1.88% 12 months after lock-in. CONCLUSIONS: Endothelial cell loss and corneal thickness change 12 months after lock-in agreed well with those reported in the literature after phacoemulsification with IOL implantation. The UV light exposure for adjustment and lock-in procedures did not add to the endothelial damage caused by the cataract surgery.

Optimized constants for an ultraviolet light-adjustable intraocular lens.

PURPOSE: To determine the accuracy of intraocular lens (IOL) power calculations and to suggest adjusted constants for implantation of ultraviolet light-adjustable IOLs. SETTING: Center for Vision Science, Ruhr University Eye Clinic, Bochum, Germany. DESIGN: Cohort study. METHODS: Eyes with a visually significant cataract that had phacoemulsification with implantation of a light-adjustable IOL were evaluated. IOLMaster measurements were performed before phacoemulsification and IOL implantation and 4 weeks after surgery before the first adjustment of the IOL. The difference in the expected refraction and estimation error was studied. RESULTS: The study evaluated 125 eyes. Using the surgical constants provided by the manufacturer of the light-adjustable IOL, the SRK/T formula gave a more hyperopic refraction than the Hoffer Q and Holladay 1 formulas. The mean error of prediction was 0.93 diopter (D) ± 0.69 (SD), 0.91 ± 0.63 D, and 0.86 ± 0.65 D, respectively. The corresponding mean absolute error of prediction was 0.98 ± 0.61 D, 0.93 ± 0.61 D, and 0.90 ± 0.59 D, respectively. With optimized constants for the formulas, the mean error of prediction was 0.00 ± 0.63 D for Hoffer Q, 0.00 ± 0.64 D for Holladay 1, and 0.00 ± 0.66 D for SRK/T. CONCLUSION: The expected refraction after phacoemulsification and implantation of a light-adjustable IOL toward the hyperopic side of the desired refraction could be considered when using the optimized constants for all formulas.

Fifty consecutive cases of transconjunctival sutureless 23-gauge vitrectomy combined with phacoemulsification and IOL implantation.

BACKGROUND AND OBJECTIVE: To evaluate safety and effectiveness of combined 23-gauge vitrectomy and phacoemulsification with intraocular lens (IOL) implantation for eyes with vitreoretinal conditions and progressed cataract. PATIENTS AND METHODS: The authors retrospectively reviewed 50 previously nonvitrectomized eyes of 50 patients with various vitreoretinal conditions and cataract affecting visual acuity. They underwent combined surgery with sutureless transconjunctival 23-gauge vitrectomy and phacoemulsification with IOL implantation. Surgical indications were a progressed cataract with various retinal conditions. RESULTS: Best-corrected visual acuity (BCVA) improved from 0.23 (range: 0.125 to 0.32; standard deviation [SD]: 0.08) to 0.48 (range: 0.32 to 0.8; SD: 0.16). Spherical equivalent changed from 0.50 to 0.08 diopters. Cataract surgery mean time was 10.46 minutes, vitrectomy mean opening time was 1.1 minutes, and mean vitrectomy procedure time varied widely depending on the type of retinal surgery (20.06 minutes; range: 5 to 55; SD: 11.10). At 1 week, relative hypotony was found in 12% and hypotony was found in 4%. There was no hypotony 3 months after surgery. CONCLUSION: Transconjunctival 23-gauge vitrectomy with phacoemulsification with IOL implantation appears effective with an acceptable safety profile for patients with cataract with simultaneous retinal diseases.

Results of higher power toric intraocular lens implantation.

PURPOSE: To evaluate the efficacy, predictability, and safety of coaxial microincision phacoemulsification and toric intraocular lens (IOL) implantation in eyes with high corneal astigmatism. SETTING: Two eye clinics in Germany. DESIGN: Case series. METHODS: Routine cataract extraction using 2.2 mm coaxial phaco equipment and Acrysof toric IOL (3.00 to 6.00 diopters [D] cylinder) implantation were performed. Examinations included optical biometry, Haigis IOL calculation, topography, and objective and subjective refractions. Retroillumination images were used to evaluate IOL alignment. Postoperative examinations were scheduled at 1 week and 3 months. RESULTS: The study enrolled 40 eyes (30 patients). The mean preoperative keratometric cylinder was 3.55 ± 0.73 D (range 2.64 to 5.39 D) and the mean 3-month postoperative subjective cylinder, 0.67 ± 0.32 D. The mean logMAR uncorrected distance visual acuity improved from 0.93 to 0.20 and the mean logMAR CDVA, from 0.41 to 0.09. The mean prediction error (spherical equivalent) was +0.14 ± 0.44 D. The mean IOL rotation between 1 week and 3 months was 0.23 ± 1.9 degrees clockwise. The mean surgically induced astigmatism was 0.08 ± 0.41 D. The alignment error was below 10 degrees in 97.5% of cases. The mean vector change in refractive cylinder between 1 week and 3 months was 0.31 ± 0.19 D. The Alpins correction index was +1.01, indicating a slight tendency toward overcorrection. CONCLUSIONS: Coaxial microincision phacoemulsification with toric IOL safely and predictably reduced high corneal astigmatism and improved surgical outcomes. Thorough planning and precise execution are necessary.

Combined correction of axial hyperopia and astigmatism using the light adjustable intraocular lens.

PURPOSE: To determine whether residual spherical and cylindrical errors could be corrected postoperatively using spatially profiled UV light irradiation in patients with axial hyperopia undergoing cataract surgery and implantation of a light adjustable, silicone intraocular lens (LAL). DESIGN: We conducted a prospective, nonrandomized clinical trial. The LALs were implanted in eyes with axial lengths <22.20 mm and were treated with a spatial intensity profile delivered by a digital light delivery device to induce a targeted spherical and cylindrical refractive change postoperatively. Once the desired correction was achieved, the LAL was treated again to lock-in the lens power. PARTICIPANTS: We studied 15 eyes of 15 patients with axial hyperopia. METHODS: The manifest refraction, uncorrected visual acuity (UCVA), and best spectacle-corrected visual acuity (BCVA) were determined with follow-up time of 12 months to determine the achieved refractive corrections and their stability. MAIN OUTCOME MEASURES: We measured UCVA, BCVA, achieved versus targeted refractive outcome, and refractive stability with a follow-up time of 12 months. RESULTS: Of 15 eyes, 14 (93%) achieved ± 0.5 diopters (D), and 10 (67%) were within ± 0.25 D of the targeted refractive adjustment up to 12 months postoperative follow-up. Only 1 treated eye showed a change of 0.38 D in manifest spherical equivalent refraction, the remaining 14 eyes showed <0.25 D change between 1 month post lock-in, and at the 3-, 6-, and 12-month postoperative visits. CONCLUSIONS: The light-adjustable lens is a promising technology with the potential to reduce the rate of postoperative refractive surprises up to 2 D of spherical and cylindrical errors after cataract surgery. Postoperative refractive errors were successfully corrected with precision and significant improvement in UCVA and without compromising BCVA using the light-adjustable intraocular lens technology. The data demonstrate the stability of the achieved refractive change after the adjustment and lock-in procedures.

Combined correction of sphere and astigmatism using the light-adjustable intraocular lens in eyes with axial myopia.

PURPOSE: To determine the efficacy of light-adjustable intraocular lenses (IOL) in correcting residual spherical and cylindrical errors in patients with axial myopia. SETTING: Center for Vision Science, Ruhr University Eye Clinic, Bochum, Germany. DESIGN: Prospective cohort study. METHODS: Light-adjustable IOLs were implanted in eyes with axial myopia and treated with spatial irradiance profiles delivered by a digital light-delivery device to induce a target spherical and/or spherocylindrical refractive change. Once the desired correction was achieved, the power of the IOL was locked in (ie, photo locking). The manifest refraction, uncorrected distance visual acuity (UDVA), and corrected distance visual acuity (CDVA) were determined 1, 6, and 12 months after lock-in to determine the achieved refractive corrections and their stability. RESULTS: Twelve months postoperatively, 20 (96%) of the 21 eyes studied were within ± 0.50 diopter (D) of the intended refractive outcome and 17 (81%) were within ± 0.25 D. One eye had a 0.325 D change in mean refractive spherical equivalent (MRSE). The change in MRSE in the other 20 eyes was less than 0.250 D between 1 month after lock-in and the 3-, 6-, and 12-month postoperative visits. CONCLUSIONS: The light-adjustable IOL reduced postoperative spherical and cylindrical errors of up to 2.00 D. Postoperative refractive errors were successfully corrected, and there was a significant improvement in UDVA with concomitant maintenance of CDVA. The achieved refractive change was stable after the adjustment and lock-in procedures.

Efficacy of different excimer laser techniques in the management of recurrent corneal erosions.

BACKGROUND AND OBJECTIVE: To investigate the efficacy of two excimer laser techniques for recurrent corneal erosions (RCEs). PATIENTS AND METHODS: Of 100 patients with RCEs not responding to common treatments, 50 received transepithelial (group 1) and 50 received subepithelial (group 2) treatment of 20 pulses of a 193-nm excimer laser (170 J/cm(2)). Postoperative follow-up occurred at 4 and 52 weeks. Outcome measures were frequency of RCEs, haze formation, and refractive changes. RESULTS: At first follow-up, 7 patients (14%) in each group displayed recurrence. At second follow-up, 12 patients in group 1 (24%) and 10 patients in group 2 (20%) had RCE. Follow-up recurrence risk was 6% to 27% in both groups at 4 weeks and 13% to 38% in group 1 and 10% to 34% in group 2 at 52 weeks. The spherical equivalent remained unaffected in group 1, but a statistically significant change was observed in group 2. CONCLUSION: Excimer laser treatment (transepithelial and subepithelial) of RCEs can be performed successfully on the intact epithelium without adjunct therapy or pain. The transepithelial technique is a simple and relatively painless way to reduce the rate of RCE and is equivalent to the well-established subepithelial treatment.

Analysis of biometry and prevalence data for corneal astigmatism in 23,239 eyes.

PURPOSE: To present and analyze biometry data sets and prevalence data for corneal astigmatism in a large population. SETTING: High-volume eye surgery center, Castrop-Rauxel, Germany. METHODS: Axial length (AL), corneal radii, anterior chamber depth (ACD), and horizontal corneal diameter (white-to-white [WTW] distance) were optically measured by partial coherence interferometry (IOLMaster). Patient data sets acquired between 2000 and 2006 were reviewed and analyzed. RESULTS: The study evaluated 23,239 data sets of 15,448 patients with a median age of 74 years. The mean values were as follows: AL, 23.43 mm +/- 1.51 (SD); corneal radius, 7.69 +/- 0.28 mm; WTW distance, 11.82 +/- 0.40 mm; and ACD, 3.11 +/- 0.43 mm. The ACD and axis of astigmatism were correlated with age. The AL, corneal radius, ACD, and WTW were correlated with one other. Eight percent of eyes had corneal astigmatism greater than 2.00 diopters (D), and 2.6% had more than 3.00 D. Astigmatism was with the rule (WTW) in 46.8% of eyes, against the rule in 34.4%, and oblique in 18.9%. High astigmatism was predominantly WTW. CONCLUSIONS: The results in this analysis might provide normative data for cataract patients and a useful reference for multiple purposes. The correlation of AL with corneal radius, ACD, and corneal diameter in normal eyes was not present in eyes with extreme myopia or hyperopia.

The combination of diffractive and refractive multifocal intraocular lenses to provide full visual function after cataract surgery.

PURPOSE: To investigate if implantation of a far dominant refractive multifocal intraocular lens (IOL) in one eye and a near dominant diffractive multifocal IOL in the fellow eye improves range of vision following cataract surgery. METHODS: This was a prospective, nonrandomized, case-control study involving 20 patients (40 eyes) scheduled for cataract surgery. Inclusion criteria were bilateral cataracts, minimum age 50 years, availability for follow-up visits, and informed consent. All patients received a far dominant refractive multifocal IOL (ReZoom, Abbott Medical Optics) in their dominant eye and a near dominant diffractive multifocal IOL (Tecnis ZM900, AMO) in their nondominant eye. Preoperative and postoperative measurements (3 months) included refraction, uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), reading acuity, and reading speed. RESULTS: All patients completed the study. We present results of the 3-month postoperative visit. The patient group comprised 14 females and 6 males, with mean age 72 years (SD 6.1 years). Postoperatively, the mean sphere was 0.05 +/- 0.31 D and the cylinder -0.31 +/- 0.37 D. At the 3-month visit, mean binocular distance UCVA was 0.080 logMAR (SD 0.070) and BCVA was 0.030 logMAR (SD 0.066). The mean binocular near visual acuity was 0.140 logMAR (SD 0.068), mean binocular best-corrected, near visual acuity 0.060 logMAR (SD 0.060). CONCLUSIONS: The combination of a far dominant refractive multifocal IOL (with better distance performance) with a near dominant diffractive multifocal IOL (with better near vision) proved to be very suitable to help meet cataract patients' visual needs.

Intermediate vision and reading speed with array, Tecnis, and ReSTOR intraocular lenses.

PURPOSE: To retrospectively evaluate reading performance at intermediate distances of three types of multifocal intraocular lenses (IOLs) under different light conditions based on reading acuity and reading speed tests. METHODS: Thirty cataract patients (60 eyes) randomly assigned to receive the Array SA40N lens (n = 20 eyes), the Tecnis ZM001 lens (n = 20 eyes), and the ReSTOR lens (n = 20 eyes) were retrospectively tested for their reading abilities at distances of 40 cm, 60 cm, and 80 cm under low light conditions (6 cd/m2) and bright light conditions (100 cd/m2). RESULTS: LogMAR distance-corrected acuity in dim (bright) light at 40 cm was 0.456 (0.363) (Array), 0.446 (0.293) (ReSTOR), and 0.299 (0.140) (Tecnis); at 60 cm, it was 0.417 (0.259) (Array), 0.448 (0.318) (ReSTOR), and 0.381 (0.121) (Tecnis); at 80 cm, it was 0.359 (0.195) (Array), 0.395 (0.245) (ReSTOR), and 0.373 (0.124) (Tecnis). Uncorrected reading speed (words/min) in dim (bright) light at 40 cm was 25 (69) (Array), 58 (138) (ReSTOR), and 110 (166) (Tecnis); at 60 cm, it was 65 (129) (Array), 58 (129) (ReSTOR), and 135 (173) (Tecnis); and at 80 cm, it was 59 (153) (Array), 79 (164) (ReSTOR), and 121 (176 (Tecnis). CONCLUSIONS: Our study indicates that Array, ReSTOR, and Tecnis IOLs provide functional intermediate vision in bright light. In dim light, however, the Tecnis IOL provides better uncorrected reading speed at intermediate distances than Array and ReSTOR IOLs.

Reading ability with 3 multifocal intraocular lens models.

PURPOSE: To prospectively evaluate reading performance with of 3 types of multifocal intraocular lenses (IOLs) under different lighting conditions based on reading acuity and reading speed tests. SETTING: Augenklinik, Bad Hersfeld, Germany. METHODS: This randomized study comprised 60 cataract patients (120 eyes) randomly assigned to receive an SA40N IOL (AMO) (Group 1, 20 patients), Tecnis ZM001 IOL (AMO) (Group 2, 20 patients), or AcrySof ReSTOR SA60D3 IOL (Alcon) (Group 3, 20 patients). Pupil size and reading ability at near (visual acuity, reading speed) without correction, with best distance correction, and with best near correction were assessed 6 weeks postoperatively under low-light conditions (6 cd/m(2)) and bright-light conditions (100 cd/m(2)) using the Radner Reading Charts. RESULTS: Six weeks postoperatively, there was no significant difference between groups in pupil size measured under low-light (6 cd/m(2)) or bright-light (100 cd/m(2)) conditions. When assessed under low-light conditions, near visual acuity and reading speed with or without correction were generally better in Group 2 than in Groups 1 and 3; there were no significant difference between Groups 1 and 3. Under bright-light conditions, Groups 2 and 3 performed significantly better than Group 1 and Group 2 performed better than Group 3. CONCLUSIONS: Under bright-light conditions, second-generation multifocal IOLs provided better reading performance than the Array SA40N IOL. However, when tested under low-light conditions, patients with the Tecnis ZM001 IOL had the best reading acuity and reading speed.