Through-Focus Response of Extended Depth of Focus Intraocular Lenses.

PURPOSE: To investigate extended depth of focus intraocular lenses (EDOF IOLs), intended to extend the depth of field after cataract surgery in a comparative study at the optical bench. METHODS: An optical bench with either green or white light was used for this study. The artificial cornea used exhibited a spherical aberration of 0.2 µm. Examinations of the following lenses with a pupil opening of 3 and 4.5 mm were carried out: AcrySof IQ Vivity (Alcon Laboratories, Inc), Isopure (PhysIOL), Tecnis Eyhance (Johnson & Johnson), Vivinex Impress (Hoya Surgical Optics), and xact (Santen). RESULTS: Using green light and a pupil aperture of 3 mm, the AcrySof IQ Vivity showed the highest light energy for the intermediate area, whereas the Isopure and Vivinex Impress provided the highest energy for distance vision. Under the same examination conditions with a pupil opening of 4.5 mm, all lenses showed a low light distribution for the intermediate range. Regarding light distribution for distance, the Tecnis Eyhance had the highest light intensity. Using white light, the curves became much wider and more similar to each other. CONCLUSIONS: The five EDOF lenses investigated differ mainly by their different weighting of energy between the far and intermediate ranges. [J Refract Surg. 2022;38(8):497-501.].

Correlation between central stromal demarcation line depth and changes in K values after corneal cross-linking (CXL).

PURPOSE: A stromal demarcation line (DL) after corneal cross-linking (CXL) has lately been suggested as a surrogate parameter for the success of CXL. The aim of this study was to investigate the correlation between depth of the central DL 1 month and the change in K values 12 months after CXL. METHODS: Treatment-naive subjects with keratoconus were treated using an accelerated CXL protocol [A-CXL(9*10)]. Depth of the DL/relative depth of the DL (DL%) was measured using Visante OCT imaging 1 month postoperatively (OP). Kmax/K2.5 (preOP) and change in Kmax/K2.5 (preOP - 12 months postOP) were assessed using corneal tomography (Pentacam HR, Oculus GmBH). RESULTS: Forty eyes were treated following the A-CXL(9*10). The mean DL depth was 200 ± 99 µm (range 71 to 479)/mean DL% = 42.70 ± 20.00% (range 17-90). There was no statistically significant correlation between stromal depth of the DL and change in Kmax or K2.5, respectively (Spearman rho DL/∆Kmax - 0.14 and DL/∆K2.5 - 0.14). Between DL% and the changes in maximum K values or K2.5, no statistically significant correlation was found as well (Spearman rho DL%/∆Kmax - 0.10 and DL%/∆K2.5 - 0.19). Mean change in Kmax after 12 months was - 0.68 ± 2.26 diopters (D) (median - 0.35 D) and - 0.82 ± 1.6 D (median - 0.65 D) for K2.5 (p = 0.07; p = 0.02). CONCLUSIONS: No statistically significant correlation was found between the stromal central depth of the DL and any outcome parameter for CXL after 12 months. Therefore, the interpretation of the DL as a predictive parameter for the effect of the procedure may not apply.

Changes in straylight and densitometry values after corneal collagen crosslinking.

PURPOSE: To evaluate the change in backward-directed and forward-directed corneal straylight in eyes after corneal collagen crosslinking (CXL) and its correlation with corrected distance visual acuity (CDVA) and changes in corneal topography. SETTING: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. DESIGN: Retrospective cohort study. METHODS: Following the Dresden protocol, corneal CXL was performed in eyes with progressive keratoconus. Corneal light scattering was evaluated using densitometry measurements from different corneal layers and zones obtained using Scheimpflug tomography (Pentacam HR). Retinal straylight values were measured using the C-Quant device. The CDVA was recorded during each follow-up examination. Changes in corneal topography were measured using Scheimpflug tomography. RESULTS: The study evaluated 31 eyes of 31 patients. The mean densitometry of different corneal layers and in 3 different zones increased 3 months postoperatively and decreased thereafter. The mean densitometry in the 0.0 to 2.0 mm zone remained statistically significantly elevated after 12 months (P < .05). The mean preoperative retinal straylight was 1.14 log(s) ± 0.28 (SD). The mean straylight peaked after 1 month and then decreased continuously but remained elevated after 1 year at 1.26 ± 0.21 log(s). There was an increase in CDVA and flattening of the steepest keratometry (K) value (maximum K). Eyes with the greatest maximum K reduction also had the highest densitometry values. CONCLUSIONS: Crosslinking-induced stromal changes resulted in an increase in densitometry, especially in the anterior stroma of the central (0.0 to 2.0 mm) zone. These changes correlated with an increase in retinal straylight but not with the postoperative CDVA values.

Long-term changes in posterior chamber phakic intraocular collamer lens vaulting in myopic patients.

OBJECTIVE: Evaluation of central and midperipheral vaulting of the posterior chamber phakic intraocular Collamer lens (ICL; Staar Surgical Inc., Monrovia, CA) in eyes with moderate to high myopia. DESIGN: Retrospective analysis of prospectively collected data. PARTICIPANTS: Eighty-four eyes treated with the latest ICL (V4 model) and 27 eyes treated with early ICL models were examined. METHODS: After standardized ICL implantation, patients underwent complete ophthalmologic examinations before surgery and at 1 week, 1 month, 3 months, 6 months, and at yearly intervals thereafter. Central vaulting was measured using the Jaeger device (Haag-Streit, Bern, Switzerland). From 2006 onward, vaulting was measured additionally by optical coherence tomography (Visante OCT; Carl Zeiss Meditec, Jena, Germany). Using the Visante OCT, the crystalline lens rise and the midperipheral vaulting of the ICL were assessed. MAIN OUTCOME MEASURES: Central vaulting after ICL implantation. RESULTS: The mean duration of follow-up was 74.1+/-23.1 months and 96.3+/-50.2 months in eyes treated with V4 and early models, respectively. Postoperative central vaulting was 466+/-218 microm (range, 30-900 microm) in eyes treated with the V4 models and 321+/-200 microm (range, 150-900 microm) in those treated with early ICL models. From the 6-month follow-up onward, a continuous and nearly linear reduction of central vaulting was observed. At the 10-year follow-up, the mean central vaulting was reduced to 184+/-159 microm (range, 6-500 microm) and 138+/-218 microm (range, 0-820 microm) in eyes treated with V4 or early models, respectively. Eyes with total vaulting had a mean central vaulting of 407+/-202 microm (range, 180-730 microm), whereas those with midperipheral contact had a significantly lower central vaulting of 105+/-87 microm (range, 0-200 microm). CONCLUSIONS: This study revealed consistent reduction of central vaulting over a 10-year period and provides further evidence that insufficient vaulting of the ICL is responsible for the development of anterior subcapsular cataract. A minimum central vaulting of 230 microm seems to be necessary to ensure total vaulting of the ICL. If an ICL is chosen for the correction of myopia, targeting for the greatest possible postoperative central vaulting is advised to achieve safe and complete vaulting for several years.

In vitro strehl ratios with spherical, aberration-free, average, and customized spherical aberration-correcting intraocular lenses.

PURPOSE: To determine in vitro image qualities of artificial eyes achieved with spherical, aberration-free, average spherical aberration-correcting, and customized spherical aberration-correcting IOLs in centered, decentered, and tilted positions. METHODS: The in vitro performance of these IOL models was determined by optical bench measurements. The experimental setup included a laser light source controlled by aperture stops that corresponded to 3- and 5-mm pupil apertures, an artificial eye with three alternative corneal models exhibiting low, intermediate, and high spherical aberration (SA), IOLs mounted to an immersed IOL holder that could be moved laterally and tilted, and a charge-coupled device camera and software to determine three-dimensional point spread function (PSF), modulation transfer function, and Strehl ratio. RESULTS: Differences among the various lens models turned out to be low for a 3-mm pupil. For a pupil aperture of 5 mm, customized IOLs showed the best results for perfect lens positioning. With ongoing decentration and tilt, customized IOLs rapidly lost their advantages, particularly in corneas with high SA and IOLs of high diopters. Spherical IOLs were always inferior to aberration-free IOLs. CONCLUSIONS: Reasonably well-centered aberration-correcting IOLs may provide considerably better image quality than conventional spherical IOLs. In the presence of significant postoperative decentration and tilt of the IOL, aberration-free IOLs are the safest option among the various intraocular lens designs.

Intraindividual comparison of color contrast sensitivity in patients with clear and blue-light-filtering intraocular lenses.

PURPOSE: To evaluate the effect of blue-light-filtering intraocular lenses (IOLs) with a yellow chromophore on color contrast sensitivity by intraindividual comparison with an identically designed IOL without a blue-light filter. SETTING: Medical University of Vienna, Department of Ophthalmology, Vienna, Austria. METHODS: Randomized implantation of an AF-1 (UV) IOL (Hoya) in 1 eye and an AF-1 (UY) IOL (Hoya) in the contralateral eye was performed after phacoemulsification and primary posterior curvilinear capsulorhexis. Three months postoperatively, the best distance-corrected visual acuity was evaluated. Before color contrast sensitivity testing, a heterochromatic flicker test was performed in both eyes to avoid error in brightness matching. Central and peripheral tritan color contrast sensitivities were evaluated using the Moorfields Vision System (CH Electronics). RESULTS: Visual acuity did not differ significantly between the 2 IOL groups (P>.05). The central color contrast sensitivity threshold also did not differ significantly between eyes with a clear IOL and eyes with a yellow IOL at any tested spatial frequency. The peripheral color contrast sensitivity test showed slightly higher color contrast sensitivity thresholds in eyes with a yellow IOL, although the differences were not statistically significant. Two patients independently reported subjective changes in color perception in the eye with the yellow IOL. CONCLUSION: In this intraindividual comparison, the implantation of a blue-light-filtering IOL did not lead to a clinically significant change in color contrast sensitivity.

Depth of focus in eyes with diffractive bifocal and refractive multifocal intraocular lenses.

PURPOSE: To evaluate monocular and binocular depth of focus in eyes with different multifocal intraocular lens (IOLs) systems. SETTING: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. METHODS: In this comparative interventional study, binocular implantation of multifocal IOLs was performed in 3 groups. In the first group, 26 eyes of 13 patients received asymmetric Acri. Twin (Acri.Tec) IOLs, a near-weighted 733D in 1 eye and a distance-weighted 737D in the fellow eye. In the second group, 26 eyes of 13 patients received a diffractive 811E IOL (Pharmacia). In the third group, 26 eyes of 13 patients received a refractive Array IOL (AMO). The visual acuity was tested monocularly and binocularly starting at 6 m in 0.50 diopter (D) defocusing steps. RESULTS: Distance visual acuity was best in eyes with the distance-dominated 737D IOL; eyes with the other IOLs had comparable results. Binocular distance visual acuity was comparable between the Acri. Twin group and the 811E group. The Acri. Twin group had better distance visual acuity than the Array group (P< or =.048). Near visual acuity was best in eyes with the near-weighted 733D, followed by the 737D and the 811E. Patients with Array IOLs had worse visual acuities at reading distance (between 33 cm and 40 cm) (P< or =.001). Patients with diffractive bifocal IOLs had better results than patients with refractive multifocal IOLs at reading distance (P< or =.018). CONCLUSION: The diffractive IOLs performed better than refractive IOLs. Asymmetric-weighted IOLs provided better binocular depth of field.

Repeatability and reproducibility of central corneal thickness measurement with Pentacam, Orbscan, and ultrasound.

PURPOSE: The purpose of this study was to compare central corneal thickness (CCT) measurements obtained with a novel rotating Scheimpflug camera (Pentacam; Oculus) with scanning slit topography (Orbscan; Bausch & Lomb), and with ultrasound pachymetry (SP-2000; Tomey). METHODS: CCT in 30 healthy eyes was measured twice with each modality by 2 independent observers in random order. The results from scanning slit topography are given both with and without multiplication with the "acoustic correction factor" of 0.92. In addition, the displayed images from the rotating Scheimpflug camera and scanning slit topography were used to calculate the signal difference-to-noise ratios (SD/N) between cornea and background signal. RESULTS: The mean CCT values as determined with the different modalities (+/-standard deviation) were: 542+/-29 microm, 576+/-37 microm, 530+/-34 microm, and 552+/-32 microm for rotating Scheimpflug imaging, for uncorrected and for corrected scanning slit pachymetry, and for ultrasound, respectively. The differences between modalities (+/-95% limits of agreement) were -9.8+/-31 microm between rotating Scheimpflug and ultrasound, 24+/-31.2 microm between scanning slit and ultrasound, and 33+/-27 microm between scanning slit and rotating Scheimpflug imaging. The limits of agreement for within and between observer effects were within 4.2% of the absolute CCT values for scanning slit and ultrasound and within 2.2% for the rotating Scheimpflug imaging. The rotating Scheimpflug camera showed similar SD/N ratios but steeper edges of the corneal surfaces in the intensity profile plots. CONCLUSION: In the assessment of normal corneas, the Pentacam measured CCT values closer to ultrasound pachymetry and with less variability compared with Orbscan. The (interobserver) reproducibility with the Pentacam was highest of all 3 modalities.

Upregulation of alphavbeta6 integrin, a potent TGF-beta1 activator, and posterior capsule opacification.

PURPOSE: To identify the predominant activation pathway of transforming growth factor (TGF)-beta1 in the lens capsule, studying the spatial and temporal expression pattern of alphavbeta6 and thrombospondin-1. Other PCO-related proteins were also studied. SETTING: Departments of Ophthalmology and Optometrics and Clinical Pathology, Medical School, University of Vienna, Vienna, Austria. METHODS: The lens capsules of 12 human donor eyes were cultivated in a protein-free medium for up to 28 days (cultivated lens capsules [CLCs]) after lens extraction. Ten intact lenses (ILs) served as the control group and were also cultured. During the culture period, cell dynamics were observed by phase-contrast microscopy. Proteins were detected by double immunofluorescence on frozen sections. RESULTS: In ILs, alphavbeta6 was absent but 91.6% of the CLCs showed extensive staining. Remnant lens epithelial cells (LECs) expressed alphavbeta6 immediately after lens extraction. The alphavbeta6 was detected throughout the culture period in all regions of the capsule. Thrombospondin-1 was absent in ILs and CLCs, suggesting that this protein is not significant in TGF-beta1 activation in the lens. Transforming growth factor-beta1 was abundantly expressed in all ILs and CLCs, slightly decreasing during intensive LEC proliferation and migration. The TGF-beta receptor II (RII) was expressed equally in all specimens, decreasing with culture time. Nonresident extracellular matrix proteins and alpha-smooth muscle actin were partially detected in CLCs but not in ILs. Latent TGF-beta binding protein 1 and collagen III were absent in all specimens. All cells found in the cultures expressed vimentin and alphaB-crystallin (LEC markers). CONCLUSION: Alphavbeta6 is the main activator of TGF-beta1 in the lens capsule and represents a new target for PCO prevention.

Contrast sensitivity function in eyes with diffractive bifocal intraocular lenses.

PURPOSE: To evaluate the image quality of asymmetric Acri. Twin bifocal intraocular lenses (IOLs) (Acri.Tec) by comparing distance and near black-white contrast sensitivity function with that of the Pharmacia 811E IOL. SETTING: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. METHODS: Thirty-two eyes of 16 patients were examined after contralateral implantation of 1 Acri. Twin near-weighted 733D IOL and 1 Acri. Twin distance-weighted 737D IOL. Twenty eyes in 10 patients were examined after binocular Pharmacia 811E IOL implantation. Best corrected distance and near visual acuities were determined. Individual reading distance was recorded and corrected to 40 cm for the near contrast test (Holladay Contrast Acuity Test). Distance contrast sensitivity function was evaluated using the Acuity Max (Science 2020) computer program. RESULTS: Best corrected distance visual acuity was significantly better in patients with the 737D IOL than in those with the 733D or 811E IOLs. For distance reading with best distance correction, the 733D IOL performed better than the 737D and the 811E. Individual reading distance with the Acri. Twin IOL and 811E IOL was 33.6 cm and 34.0 cm, respectively. Best distance-corrected near contrast sensitivity function was better in eyes with the near-weighted 733D IOL. Binocular testing showed a significant difference between the 2 groups only at low-contrast values. At distance, contrast sensitivity function was better with the 737D IOL, whereas no difference was found between the 733D and the 811E IOLs. Binocular contrast sensitivity function at distance revealed statistically significantly better results in the Acri. Twin group. CONCLUSION: An asymmetric diffractive bifocal lens system was advantageous in terms of vision quality when implanted binocularly and superior to monocular stronger weighted focus compared with conventional bifocal IOLs.

Long-term results of implantation of phakic posterior chamber intraocular lenses.

PURPOSE: To study the incidence and progression of lens opacification after implantation of phakic posterior chamber intraocular lenses for myopia and its correlation with vaulting and endothelial cell density (ECD). SETTING: Department of Ophthalmology, University of Vienna Medical School, Vienna, Austria. METHODS: An implantable contact lens (ICL V4, Staar Surgical Inc.) was inserted in 76 myopic eyes. Patients were prospectively followed preoperatively and at 1, 3, 6, 12, 24, and 36 months. The uncorrected visual acuity and best corrected visual acuity (BCVA) were determined. Vaulting was measured optically with a Jaeger II pachymeter, and the crystalline lens was examined at the slitlamp for the presence and characteristics of opacification. Endothelial cell morphometry was performed by specular microscopy, and the ECD was calculated. Eyes in which lens opacification developed were followed for at least 12 months to determine the degree and course of visual impairment. RESULTS: Lens opacification occurred in 11 eyes (14.5%). Opacification was correlated with intraoperative trauma to the crystalline lens, age older than 50 years, and decreased ECD values throughout the observation period. Vaulting of the ICL did not correlate with the risk for lens opacification. After onset of lens opacification, 6 eyes (55%) had a stable BCVA within +/-0.5 lines and 5 eyes had progressive opacification, losing between 3.5 lines and 0.5 lines (mean 1.8 lines +/- 1.1 [SD]). Three eyes (3.9%) in the progressive group had a 1- to 2-line loss of BCVA over preoperative values and subsequently had cataract surgery. CONCLUSIONS: Risk factors for lens opacification after implantation of the model V4 ICL included intraoperative trauma to the crystalline lens and older age. Decreased ECD in eyes with opacification suggests ongoing inflammation as a cause. Patients younger than 45 years may have a significantly lower incidence of opacification.

Influence of spectacle-related changes in retinal image size on contrast sensitivity function after laser in situ keratomileusis.

PURPOSE: To evaluate changes in contrast sensitivity after laser in situ keratomileusis (LASIK) for the correction of myopia using a monitor-based method and considering the preoperative minification effect of high-diopter spectacles. SETTING: Department of Ophthalmology, University of Vienna Medical School, Vienna, Austria. METHODS: Fifteen eyes of 11 patients had LASIK to correct myopia. The best corrected visual acuity (BCVA) and contrast sensitivity function (CSF) were measured preoperatively and 1, 3, and 6 months postoperatively using the AcuityMax (Science 2020) computer program. The error in contrast sensitivity measurement due to different angular sizes of the test figures deriving from the spectacle refractions before and after LASIK were considered. RESULTS: Preoperatively, and at 1, 3, and 6 months, the mean Snellen BCVA was 0.93 +/- 0.19 (SD), 0.80 +/- 0.26, 0.85 +/- 0.21, and 0.84 +/- 0.27, respectively. The best mean CS (measured at 1.1 logMAR) was 1.17 +/- 0.05, 1.12 +/- 0.07, 1.13 +/- 0.08, and 1.18 +/- 0.04, respectively. The strongest CS changes were observed at 0.7 logMAR (6 cycles per degree), where CS was 1.10 +/- 0.07 preoperatively and 1.06 +/- 0.09, 1.07 +/- 0.12, and 1.14 +/- 0.07, at 1 month, 3 months, and 6 months, respectively. With correction for the spectacle effect, the preoperative CS was approximately 3% higher and CS at 3 months for intermediate optotype sizes was significantly inferior to preoperatively. CONCLUSIONS: With correction of different retinal image sizes before and after LASIK (due to different spectacle refraction), the CS was significantly below the preoperative values at 1 and 3 months and approached the preoperative values at 6 months. The proposed method is potentially capable of quality monitoring and method comparisons after photorefractive surgery.

Outcome after treatment of ametropia with implantable contact lenses.

OBJECTIVE: To evaluate long-term results after insertion of implantable contact lenses (ICLs) in phakic eyes. DESIGN: Prospective, noncomparative, interventional case series. PARTICIPANTS: Seventy-five phakic eyes (65 myopic, 10 hyperopic eyes) of 45 patients aged 21.7 to 60.6 years were included. INTERVENTION: STAAR Collamer Implantable Contact Lenses (STAAR Surgical Inc., Nidau, Switzerland) were implanted for correction of high myopia and hyperopia. MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), and intraocular pressure (IOP) were determined. Presence of lens opacification and the distance between the ICL and the crystalline lens were assessed by slit-lamp examination before surgery and at 1, 3, 6 months, and yearly after lens implantation. RESULTS: Preoperative mean spherical equivalent was -16.23+/-5.29 diopters (D) for myopic eyes and +7.88 +/-1.46 D for hyperopic eyes. After ICL implantation, mean residual refractive error was -1.77+/-2.17 D in myopic patients and +0.44+/-0.69 D in hyperopic patients. Preoperative mean UCVA was Snellen 0.03+/-0.03 for myopic patients and Snellen 0.12+/-0.16 for hyperopic patients. Preoperative mean BCVA was Snellen 0.49+/-0.23 for myopic patients and Snellen 0.82+/-0.23 for hyperopic patients. After ICL implantation, mean UCVA up to the end of individual observation time was Snellen 0.36+/-0.36 for myopic patients and Snellen 0.58+/-0.28 for hyperopic patients. Mean BCVA was Snellen 0.73+/-0.26 for myopic and Snellen 0.80+/-0.24 for hyperopic patients. Mean preoperative IOP was 14.2+/-2.7 mmHg, and mean postoperative IOP was 13.46+/-2.1 mmHg over all follow-up investigations. The main complication was the development of subcapsular anterior opacifications of the crystalline lens in 25 eyes (33.3%), 2 of which showed direct contact to the ICL. Eleven eyes (14.7%) were stable in opacification and 14 eyes (18.7%) had progressive opacifications. The median time to opacification was 27.1 months. In 8 patients (10.7%), the subjective visual impairment mandated cataract surgery. CONCLUSIONS: The most significant long-term complication after ICL implantation is the formation of opacifications of the crystalline lens with the risk of the necessity of subsequent cataract surgery (10.7%). Old age, female gender, and contralateral opacification are independent significant risk factors for early formation of opacifications in this patient group.

Effect of tenascin and fibronectin on the migration of human corneal fibroblasts.

PURPOSE: To investigate the effect of fibronectin and tenascin on the migration of corneal fibroblasts. SETTING: Department of Ophthalmology, University of Vienna, Medical School, Vienna, Austria. METHODS: Using human corneal fibroblasts, a monolayer migration assay was performed to measure corneal fibroblast movement. The migration on collagen I, fibronectin, and tenascin with and without transforming growth factor (TGF)-alpha/fibroblast growth factor (FGF)-2 stimulation and the effect of soluble tenascin and fibronectin on corneal fibroblast migration on collagen-I-coated wells were investigated. RESULTS: The cytokines TGF-alpha and FGF-2 stimulated migrational activity of corneal stromal cells in a dose-dependent manner, reaching the maximum effect at 100 ng/mL and 10 ng/mL, respectively. The migration of corneal fibroblasts on fibronectin was significantly higher (P <.05) than the migration on collagen I. Transforming growth factor-alpha and FGF-2 increased radial cell displacement independent of the provided matrix composition. Tenascin had a negative effect on corneal fibroblast adhesion/migration in this in vitro model. CONCLUSION: Fibronectin and tenascin influenced corneal fibroblast migration and adhesion, respectively, and may play a role in stromal cell movement during wound healing. The cytokines TGF-alpha and FGF-2 had an additive effect on corneal fibroblast migration on a fibronectin matrix.

Glare and halo phenomena after laser in situ keratomileusis.

PURPOSE: To simulate and measure subjectively observed glare and halos after laser in situ keratomileusis (LASIK). SETTING: University of Vienna, Medical School, Department of Ophthalmology, Vienna, Austria. METHODS: In 16 eyes of 10 patients, the best corrected visual acuity (BCVA) and subjectively observed glare and halo size under mesopic conditions were measured before LASIK and 1, 3, and 6 months postoperatively. Infrared pupillography was used to ensure that all patients had a larger ablation zone than the measured pupil size under mesopic conditions. RESULTS: Preoperatively, the mean Snellen BCVA was 0.88 +/- 0.17 (SD) and the mean glare and halo size was 1.97 +/- 1.20 square degrees (sqd) before the treatment. One month after LASIK, the BCVA was 0.83 +/- 0.29 and the mean glare and halo size, 2.61 +/- 3.14 sqd. Three months after LASIK, the mean values were 0.90 +/- 0.26 and 1.88 +/- 2.37 sqd, respectively. Six months after LASIK treatment, they were 0.85 +/- 0.28 and 1.30 +/- 1.63 sqd, respectively. The 95% confidence interval for the difference between preoperative glare and halo and glare and halo at 6 months was -1.56 to + 0.51 sqd. CONCLUSIONS: Subjectively observed glare and halo size after LASIK reached a peak after 1 month and decreased in the following postoperative period.

Comparison of visual acuities at different distances and defocus curves.

PURPOSE: To evaluate how visual acuities at different distances correlate with results from defocus curves. SETTING: Department of Ophthalmology and Institute of Medical Physics, University of Vienna, Medical School, Vienna, and Department of Ophthalmology, Krankenhaus St. Pölten, St. Pölten, Austria. METHODS: This study comprised 15 eyes of 14 patients with a mean age of 67.9 years +/- 9.7 (SD) with a monofocal silicone intraocular lens (911A, Pharmacia). The best corrected distance visual acuity was determined at viewing distances of 6 m, 2 m, 1 m, 67 cm, 50 cm, 40 cm, and 33 cm using logMAR charts. Defocus curves were then evaluated from -3.0 to -0.5 diopter (D) at 0.5 D increments from the best distance correction at a viewing distance of 6 m. RESULTS: The mean distance visual acuity was logMAR 0.08 +/- 0.07. The visual acuity graph from the testing at different distances was above the defocus graph at all testing points. Comparison of the visual acuity results from the 2 tests revealed statistically significant differences in the range from 2 m (-0.5 D) to 33 cm (-3.0 D). CONCLUSIONS: Results of defocus curves disregard the diminutions of minus glasses, the normally restricted viewing distance to 6 m for distance acuity determination, and in particular the physiological miosis caused by the near-point reaction.

Changes of axial length and keratometry after keratoplasty for keratoconus using the guided trephine system.

PURPOSE: The purpose of this study was to examine the cause of increasing myopia after penetrating keratoplasty for keratoconus with the guided trephine system. DESIGN: Prospective interventional study cohort. METHODS: Thirty eyes (28 patients) after keratoplasty for keratoconus were examined. Preoperatively and 1, 3, 6, 12, and 24 months postoperatively subjective refraction was evaluated. Keratometry was calculated with a computerized videokeratoscope (TMS-1). Axial length was measured using applanation ultrasonography before surgery and 2 years after surgery. Anterior chamber depth, lens thickness, and vitreous length were taken into consideration. RESULTS: The mean spherical equivalent was + 2.22 +/- 3.47 diopters 1 month postoperatively and had a continuous myopic shift to -1.02 +/- 2.65 diopters 2 years postoperatively. This was associated with a significant increase in mean keratometric levels from + 41.72 +/- 2.96 diopters 1 month postoperatively to + 43.77 +/- 2.29 diopters 2 years postoperatively (r(s) = -0.36, P =.05). Overall, no significant changes in axial length were observed. However, vitreous length showed a small but statistically significant increase. As expected, mean anterior chamber depth decreased significantly postoperatively (P

Long-term endothelial changes in phakic eyes with posterior chamber intraocular lenses.

PURPOSE: To evaluate the long-term endothelial cell changes in phakic eyes after implantation of a posterior chamber phakic intraocular lens to correct high ametropia. SETTING: Department of Ophthalmology, University Hospital of Vienna, Vienna, Austria. METHODS: Thirty-four eyes of 21 patients having implantation of an implantable contact lens (ICL, Staar Surgical) for high myopia or hyperopia were prospectively examined. The minimum follow-up was 2 to 4 years. Preoperative and serial postoperative specular microscopy (Noncon Robo SP 8000, Konan) was performed to evaluate the long-term endothelial cell changes. RESULTS: The mean preoperative endothelial cell density was 2854 cells/mm(2). The mean endothelial cell loss from preoperatively was 1.8% at 3 months, 4.2% at 6 months, 5.5% at 12 months, 7.9% at 2 years (n = 34), 12.9% at 3 years (n = 13), and 12.3% at 4 years (n = 11). All other endothelial cell characteristics remained stable during the 4-year follow-up. CONCLUSIONS: Continuous endothelial cell loss was observed after ICL implantation during a 4-year follow-up. There was rapid cell loss until 1 year postoperatively, after which the rate of loss was no longer statistically significant. The percentage of hexagonal cells (polymorphism) and the coefficient of variation (polymegethism) remained stable during the 4-year follow-up.

Quantitative performance of bifocal and multifocal intraocular lenses in a model eye: point spread function in multifocal intraocular lenses.

OBJECTIVE: To compare the optical properties of bifocal diffractive and multifocal refractive intraocular lenses. METHODS: A model eye with a pupil 4.5 mm in diameter was used to determine the point spread function (PSF) of the distance focus and near focus of a diffractive bifocal intraocular lens (IOL) (model 811E; Pharmacia Inc, Columbus, Ohio) and of a refractive multifocal IOL (model SA40N; Allergan Optical Inc, Irvine, Calif) to compare them with PSFs of foci of corresponding monofocal lenses. For interpreting the PSFs the through focus response, the modulation transfer function, and the Strehl ratio were evaluated. RESULTS: The intensity of the distance focus of the bifocal diffractive lens reached 58.5% and the near focus attained 42.7% of the intensity of a corresponding monofocal lens. The maximal halo intensity surrounding both foci was approximately 4.5%. The distance peak of the refractive multifocal IOL was 73.4% and the near peak 25.1% of a corresponding monofocal lens. The out-of-focus image overlaying the distance focus of the refractive multifocal IOL was approximately 3% of the light intensity of the distance focus, whereas the PSF of the near focus of the multifocal IOL is substantially affected by out-of-focus images. The computed modulation transfer functions show better results for the monofocal lenses, similar results for the tested distance foci, and clear advantages for the bifocal diffractive near focus. CONCLUSIONS: Modulation transfer functions reveal comparable properties for distance vision and a superiority of the bifocal diffractive lens over the refractive multifocal lens for near vision.