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.

Imaging of birefringent properties of keratoconus corneas by polarization-sensitive optical coherence tomography.

PURPOSE: To investigate and map the polarizing properties of keratoconus corneas in vitro and to compare the results with those obtained in normal corneas. METHODS: Corneal buttons of five keratoconus corneas were investigated by polarization-sensitive optical coherence tomography (PS-OCT). The instrument measures backscattered intensity (conventional OCT), retardation, and (cumulative) slow axis distribution simultaneously. Three-dimensional (3-D) data sets of the polarizing parameters are recorded, and two-dimensional (2-D) cross-sectional images as well as en face images of the distribution of these parameters at the posterior corneal surface are derived. The results are compared to similar maps obtained from normal corneas. RESULTS: Compared with normal corneas, the retardation and slow axis orientation patterns are heavily distorted in keratoconus corneas. Larger areas of increased and decreased retardation can be found in keratoconus corneas, markedly increased retardation (up to >50 degrees ) can especially be found near the rim of corneal thinning. Contrary to normal corneas, regions where the slow axis markedly changes with depth (by up to 50 degrees -90 degrees ) are observed in keratoconus. CONCLUSIONS: The observed changes in the cornea's birefringence properties indicate a change in the arrangement of collagen fibrils in the corneal stroma associated with keratoconus. PS-OCT may be a useful tool for the study and diagnosis of corneal disease.

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.

Validity and repeatability of anterior chamber depth measurements with Pentacam and Orbscan.

PURPOSE: The purpose of this study was to determine the validity and repeatability of anterior chamber depth (ACD) measurements obtained with a novel rotating Scheimpflug camera (Pentacam; Oculus Optikgeräte GmbH, Wetzlar, Germany) to scanning slit topography (Orbscan; Bausch & Lomb, Rochester, NY). METHODS: ACD in 60 healthy eyes was measured twice by two independent observers with each modality in random order. A total of eight measurements was performed on each eye. The mean differences between measurements, between observers, and between modalities were calculated, and 95% limits of agreement (LoA) were given as mean +/- 1.96 * standard deviation (SD) of the mean. RESULTS: The mean ACD values as determined with the different modalities (+/- SD) were 3.18 +/- 0.38 mm for Pentacam imaging and 3.23 +/- 0.40 for Orbscan. The mean difference between the two modalities was 0.047 mm (LoA: 0.176 to -0.081 mm). Within each modality, the limits of agreement of the differences between individual measurements and between different observers were within 0.073 mm or 4% of total ACD. The total variance in the observed data was 0.145. The variance resulting from interindividual differences in ACD was 85%, as a result of the two different modalities 15%, as a result of different observers 0.007%, and as a result of different measurements 0.007%. CONCLUSIONS: In the assessment of normal eyes, the differences of ACD values measured with Orbscan and Pentacam were within clinically acceptable levels, and inter- and intraobserver variability was considerably below clinically significant levels. Thus, these two modalities can be regarded as interchangeable.

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.

Central corneal thickness measurements with partial coherence interferometry, ultrasound, and the Orbscan system.

OBJECTIVE: To compare the reliability of central corneal thickness measurements (CCT) obtained with partial coherence interferometry (PCI), ultrasound pachymetry, and the Orbscan system. DESIGN: Cross-sectional study. PARTICIPANTS: Twenty healthy subjects with CCT measurements in both eyes. METHODS: The CCT measurements were obtained with PCI, ultrasound pachymetry, and the Orbscan system. In each eye, 2 investigators performed 5 repeated measurements with each pachymetric device. Intraclass correlation coefficients (kappa) were calculated and mean CCT measurements were compared. MAIN OUTCOME MEASURES: The CCT measurements obtained with ultrasound pachymetry, the Orbscan system (Orbtek Inc., Salt Lake City, UT), and PCI. RESULTS: Mean CCT values measured with ultrasound pachymetry were significantly thicker than those measured with PCI (21.5 microm; P<0.001) or the Orbscan system (19.8 microm; P<0.001). The correlation coefficients for the intraobserver variability were 0.999 for PCI measurements, 0.983 for ultrasound pachymetry measurements, and 0.988 for Orbscan system measurements. The correlation coefficients for the interobserver variability were 0.998 for PCI measurements, 0.980 for ultrasound pachymetry measurements, and 0.988 for Orbscan system measurements. There was a slightly better consistency between ultrasound pachymetry and PCI (kappa = 0.96) than between the Orbscan system and PCI (kappa = 0.92) and between ultrasound pachymetry and the Orbscan system (kappa = 0.89). CONCLUSIONS: Partial coherence interferometry was the method with the least intraobserver or interobserver variability. Mean CCT as measured with ultrasound pachymetry was approximately 20 microm thicker than with the Orbscan system and PCI. However, corneal thickness measurements with ultrasound pachymetry and PCI were slightly more consistent than those of the Orbscan system and PCI. This slightly better consistency, however, may be important, especially in corneal refractive surgery.

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.

Effect of accommodation and pupil size on the movement of a posterior chamber lens in the phakic eye.

PURPOSE: Although a posterior chamber phakic intraocular lens provides effective refractive correction of high myopia and hyperopia, mechanical contact between the implantable contact lens (ICL) and the crystalline lens and inadequate aqueous circulation in the prelenticular space could cause subcapsular opacification. To assess whether and to what extent such mechanical contact occurs, changes in the distance between the STAAR Collamer ICL and the crystalline lens under various conditions were investigated. DESIGN: Open pilot study. PARTICIPANTS: Thirteen eyes of 11 myopic and 2 hyperopic patients with a mean age of 38 years (range, 19-53 years) were examined at least 6 months after ICL implantation. METHODS: A noninvasive, high-resolution biometry technique, partial coherence interferometry, was used to measure distance changes between the ICL and the crystalline lens during subjective accommodation, after instillation of pilocarpine, and under changing light conditions. MAIN OUTCOME MEASURES: Mean distance changes from the posterior corneal surface to the ICL, from the posterior corneal surface to the anterior surface of the crystalline lens, and the distance between the ICL and the crystalline lens. RESULTS: In the nonaccommodated state, the mean distance between the ICL and the crystalline lens was 457 microm (range, 123-924 microm). During subjective accommodation, a significant (P<0.01) decrease and, after topical application of pilocarpine, a nonsignificant (P=0.35) decrease of anterior chamber depth was accompanied by a nonsignificant (P = 0.71) reduction of the ICL-crystalline lens distance. Under photopic conditions, a significant mean reduction (P<0.01) of the ICL-crystalline lens distance of -28 microm (range, -16 to -188 microm) was observed. CONCLUSIONS: Partial coherence interferometry biometry enabled noninvasive high-precision investigation of ICL dynamics. No significant changes between the ICL and the crystalline lens were detected during subjective accommodation and after application of pilocarpine. However, under photopic conditions, with constriction of the pupil, the distance between the ICL and the crystalline lens was significantly reduced. This mechanism might cause inadequate aqueous circulation in the prelenticular space and might be one of the causes of subcapsular opacification in some of the eyes after ICL implantation.

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 ultrasound pachymetry and partial coherence interferometry in the measurement of central corneal thickness.

PURPOSE: To compare central corneal thickness (CCT) measurements obtained with 3 ultrasound pachymeters and with partial coherence interferometry (PCI) and evaluate the effect of repeated contact by a pachymetry probe on corneal thickness. SETTING: Department of Ophthalmology, University of Vienna, Vienna, Austria. METHODS: Central corneal thickness was measured in 20 eyes of 20 healthy volunteers with 3 different ultrasound pachymeters (DGH 500, DGH Technology Inc.; SP 2000, Tomey Inc.; Paxis, Biovision Inc.) and with PCI. In each eye, 5 measurements with PCI were followed by 5 measurements with each ultrasound pachymetry device and another 5 measurements with PCI. RESULTS: The mean CCT measured with the DGH 500, SP 2000, and Paxis was 541.0 microm, 539.2 microm, and 545.1 microm, respectively. Although the differences among the 3 ultrasound pachymetry devices were within 6.0 microm, they were statistically significant (P<.05). The PCI measurements were significantly smaller (P <.05) than the ultrasound measurements: 518.8 microm before and 517.5 microm after repeated contact with the ultrasound pachymetry probe (P <.05). The mean precision (standard deviation) was 0.77 microm for PCI and between 2.40 microm and 3.58 microm for ultrasound pachymetry measurements. The correlation coefficients for the intraobserver variability were 0.999 for PCI and between 0.987 and 0.995 for ultrasound pachymetry measurements. CONCLUSIONS: Partial coherence interferometry was the more precise method of measuring CCT and had better intraobserver variability. Repeated contact by a pachymetry probe reduced corneal thickness by 1.3 microm. However, the reason for the smaller measurements with PCI than with ultrasound pachymetry remains unclear.

Reading performance with a refractive multifocal and a diffractive bifocal intraocular lens.

PURPOSE: To evaluate the reading performance of a diffractive bifocal (811E, Pharmacia) and a refractive multifocal (SA40N, Allergan) intraocular lens (IOL) and compare it with that of a monofocal IOL (811C, Pharmacia) with respect to reading acuity, reading speed based on print size, maximum reading speed, reading distance, and critical print size. SETTING: Department of Ophthalmology, University of Vienna, Vienna, Austria. METHODS: This study comprised 120 pseudophakic eyes of 70 patients; each IOL group had 40 eyes. The patients' age, sex, and best corrected logMAR visual acuity were recorded. Reading acuity and speed were tested monocularly. Reading acuity was determined in logRAD (ie, the reading equivalent of logMAR). Patients with bifocal and multifocal IOLs read with best distance correction and patients with a monofocal IOL, with an addition of +3.0 diopters. RESULTS: The age, mean spherical equivalent, cylinder, and best corrected distance visual acuity were comparable among the 3 groups. The mean logRAD reading acuity was 0.17 +/- 0.18 (SD) in the 811E group (94.0% of logMAR), 0.31 +/- 0.13 in the SA40N group (73.2% of logMAR), and 0.24 +/- 0.22 in the 811C group (94.1% of logMAR). The reading acuity in the SA40N group was statistically significantly lower than in the 811E and 811C groups. The best reading distance was 30 cm in the 811E group and 40 cm in the SA40N group. The mean maximum reading speeds in words per minute were comparable: 187.5 +/- 26.1 (811E), 171.0 +/- 21.1 (SA40N), and 179.4 +/- 21.6 (811C). The reading speed, which ranged from logRAD 0.7 to 0.3, and the critical print size in the SA40N group were significantly worse than in the 811E and 811C groups. The mean critical print size in the 811E group was significantly worse than in the 811C group. CONCLUSIONS: Reading performance was acceptable in the bifocal and multifocal IOL patients, with the diffractive bifocal IOL performing best in a standardized reading test setting.

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.