The future role of wavefront-guided excimer ablation.
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Forecasting↗
Biomedical subjects
Thomas Kohnen
Publications and source records attributed to Thomas Kohnen.
European multicenter study of the AcrySof ReSTOR apodized diffractive intraocular lens.
OBJECTIVE: To report the safety and effectiveness of the AcrySof ReSTOR apodized diffractive intraocular lens (IOL), model MA60D3, when implanted into the capsular bag. DESIGN: Multicenter European study including university clinics, eye hospitals, and private ophthalmic surgical centers. PARTICIPANTS: One hundred twenty-seven subjects implanted in cataractous eyes in an open multicenter study. INTERVENTION: After phacoemulsification, the foldable 3-piece hydrophobic acrylic apodized diffractive IOL was implanted in the capsular bag using a Monarch injector with an A-cartridge. The mean preoperative patient age was 68.4+/-12 years. Intraocular lens implant power ranged from 18.0 to 25.0 diopters (D) in 0.5-D increments. MAIN OUTCOME MEASURES: Distance visual acuity (VA), near VA, spectacle dependence, unwanted visual symptoms, and patient satisfaction. RESULTS: At the 6-month postoperative visit, binocular (both eyes simultaneously) mean uncorrected distance and near logarithm of the minimum angle of resolution VAs for the MA60D3 were 0.04+/-0.14 and 0.09+/-0.12 (n = 118), respectively. In addition, 88.0% and 84.6% of ReSTOR subjects achieved spectacle independence for distance and near vision, respectively. Glare and halos were reported as severe by only 8.5% and 4.2% of patients, respectively. Ninety-two percent of patients stated that they would choose to have the same lens implanted again after the first implant, and 95.7% answered likewise after the second implant. CONCLUSIONS: The AcrySof ReSTOR MA60D3 IOL demonstrated excellent near VA without compromising distance vision. Spectacle independence and patient satisfaction were high, whereas unwanted photic phenomena were clinically acceptable.
Acrylic Resins↗
Intraindividual comparison of higher-order aberrations after implantation of aspherical and spherical intraocular lenses as a function of pupil diameter.
PURPOSE: To compare intraindividual higher-order wavefront aberrations after implantation of aspherical and spherical intraocular lenses (IOLs) as function of pupil diameter. SETTING: Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany. METHODS: In this prospective study, wavefront measurements of 21 patients after implantation of a spherical IOL (AMO AR40e) in 1 eye and an aspherical IOL (AMO Tecnis) in the contralateral eye were analyzed. Third-, 4th-, 5th-, total higher-order aberration (HOA) root-mean-square (RMS), and primary spherical aberration (Z(4)(0)) were compared at different virtual pupil diameters of 3 to 6 mm. RESULTS: For both IOLs and each higher order analyzed, values increased with increasing pupil diameter. Fourth-order RMS and Z(4)(0) in the aspherical IOL group were significantly lower than with the spherical IOL at all analyzed pupil diameters. The total HOA RMS of the aspherical IOL was significantly lower than the spherical IOL only at 6 mm pupil diameter. For 3rd- and 5th-order RMS, no significant difference was found between the tested IOLs at any pupil diameter. CONCLUSION: In comparison to a spherical IOL, the aspherical Tecnis IOL reduced Z(4)(0) and 4th-order RMS significantly for pupil diameters of 3 to 6 mm, whereas total HOA RMS was only significantly reduced for a pupil diameter of 6 mm.
Aged↗
Consultation Section: refractive surgical problem.
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Adult↗
Factors affecting the change in lower-order and higher-order aberrations after wavefront-guided laser in situ keratomileusis for myopia with the Zyoptix 3.1 system.
PURPOSE: To identify factors that affect the change in lower- and higher-order wavefront aberrations after myopic wavefront-guided laser in situ keratomileusis (wg-LASIK). SETTING: Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany. METHODS: Sixty myopic eyes of 32 patients were treated with wg-LASIK (Zyoptix version 3.1, Bausch & Lomb) and had an uneventful follow-up of 12 months. Wavefront errors were measured preoperatively and 12 months after LASIK and were computed for pupil diameters (PDs) of 3.5 mm and 6.0 mm. Multiple stepwise regression analysis was performed to assess the influence of patient age, spherical equivalent (SE), sphere, cylinder, optical zone (OZ) diameter, and the preoperative individual Zernike coefficients on lower- and higher-order aberration (HOA) change. RESULTS: The mean preoperative SE was -5.59 diopters (D) +/- 2.20 (SD) (range -1.00 to -9.50 D); the mean OZ diameter was 6.70 +/- 0.68 mm (range 5.6 to 8.1 mm). Reduction in almost all Zernike coefficients was influenced significantly by the preoperative amount of the individual coefficient. The effect varied among the coefficients and was lower with the 6.0 mm PD. With the 3.5 mm PD, age, SE, sphere, cylinder, and OZ diameter did not have a significant effect on individual Zernike coefficients. With the 6.0 mm PD, SE and OZ diameter had a significant effect on the induction of Z4(0); the OZ diameter also had an effect on the induction of coma root mean square. CONCLUSIONS: Three groups of factors influenced the change in HOAs: The negative correlation with the magnitude of preoperative HOA values reflected the effect of the wavefront-guided algorithm. The SE and OZ diameter affected the inadvertent induction of spherical aberrations. Randomly acting effects such as decentration or flap creation, which were not included in the model, affected the induction of HOAs, particularly coma-like terms.
Adult↗
Classification of excimer laser profiles.
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Algorithms↗
Excimer laser refractive surgery in autoimmune diseases.
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Autoimmune Diseases↗
Visual performance of aspherical and spherical intraocular lenses: intraindividual comparison of visual acuity, contrast sensitivity, and higher-order aberrations.
PURPOSE: To intraindividually compare visual performance in terms of photopic high-contrast visual acuity (HCVA), mesopic HCVA, mesopic low-contrast visual acuity (LCVA), and contrast sensitivity (CS) in patients after implantation of either an aspherical or a spherical intraocular lens (IOL). SETTING: Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany. METHODS: Forty eyes of 20 patients were randomized to implantation of an aspherical IOL (Tecnis Z9000, AMO) in 1 eye and a spherical IOL (Sensar AR40e, AMO) in the other eye. Three to 4 months postoperatively, photopic HCVA (270 cd/m(2)) was measured with the observer-independent Frankfurt-Freiburg Contrast and Acuity Test System (FF-CATS) and high-mesopic HCVA and LCVA (8 cd/m(2)) were measured with Early Treatment Diabetic Retinopathy Study charts. CS was assessed with the FF-CATS under photopic (167 cd/m(2)), high-mesopic (1.67 cd/m(2)), and low-mesopic (0.167 cd/m(2)) luminance conditions with and without glare. For each individual eye, higher-order wavefront aberrations were reconstructed for a physiological mesopic pupil diameter. Intraindividual differences (Delta(i)) in visual acuity, contrast sensitivity, and higher-order aberrations (HOAs) were calculated, and the influence of age and Delta(i) HOA on Delta(i) contrast sensitivity (logCS) under high-mesopic conditions was investigated using multiple regression analysis. RESULTS: There were no statistically significant differences between the Tecnis IOL and the Sensar IOL in visual acuity measurements or contrast sensitivity measurements. For physiological mesopic pupil diameter, primary spherical aberration (Z(4)(0)) was significantly lower in the Tecnis group (P<.001). For all parameters studied except Z(4)(0), the Delta(i) values were distributed around zero. Multiple regression analysis showed only a partial influence of Delta(i) Z(4)(0) on Delta(i) logCS (adjusted R(2) = 0.49) but did not show any influence of age, coma-like aberration, or residual HOA. CONCLUSIONS: Although Z(4)(0) was significantly lower in the eyes with the aspherical IOL, no statistically significant differences were found between aspherical and spherical IOLs in LCVA, HCVA, and contrast sensitivity. Statistical analysis of intraindividual contrast sensitivity differences showed that in most patients, this Z(4)(0) difference was too low to have an effect on contrast sensitivity.
Aged↗
Internal anterior chamber diameter using optical coherence tomography compared with white-to-white distances using automated measurements.
PURPOSE: To compare internal horizontal anterior chamber (AC) diameter determined by optical coherence tomography (OCT) and horizontal corneal diameter (white-to-white [WTW]) using automated measurements. SETTING: Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany. METHODS: Internal AC diameter and WTW distance was measured in 52 eyes of 26 patients using the Visante OCT (Carl Zeiss Meditec), IOLMaster (Carl Zeiss Meditec), and Orbscan IIz topography system (Bausch & Lomb). Statistical evaluation was performed using the Bland-Altman method and regression analysis for comparison of measurement techniques. The Kruskal-Wallis test was used to measure the repeatability of each device. RESULTS: The mean internal AC diameter was 12.45 mm +/- 0.53 (SD) with OCT; the mean WTW distance was 12.17 +/- 0.45 mm with the IOLMaster and 11.84 +/- 0.41 mm with the Orbscan IIz. A positive regression was determined for AC diameter and both WTW measurements. Measurement values varied little between both WTW measurement systems (R(2) = 0.9384). CONCLUSIONS: Anterior chamber measurement using optical coherence tomography (Visante OCT) was easy to handle and showed good repeatability. The internal horizontal diameter of the AC was larger than the horizontal corneal diameter determined by automated WTW measurements (IOLMaster, Orbscan IIz). Optical coherence tomography with the Visante OCT allows direct measurement of the AC width.
Adult↗
Scheimpflug measurement of intraocular lens position after piggyback implantation of foldable intraocular lenses in eyes with high hyperopia.
PURPOSE: To investigate the position of 3-piece foldable intraocular lenses (IOLs) after piggyback implantation for high hyperopia. SETTING: University Eye Hospital, Johann Wolfgang Goethe University, Frankfurt am Main, Germany. METHODS: Eight eyes of 5 highly hyperopic patients had phacoemulsification and implantation of 2 foldable IOLs. In 3 eyes, both IOLs were implanted in the capsular bag. In 5 eyes, 1 IOL was placed in the capsular bag and the second IOL in the ciliary sulcus. Intraocular lens optic tilt and decentration, combined thickness of both IOLs, and anterior chamber depth (ACD) were measured postoperatively over a period of 18 months using Scheimpflug photography. RESULTS: All eyes with both IOLs in the capsular bag showed interpseudophakic opacification, with a mean increase in combined IOL thickness of 0.4 mm, a decrease in ACD of 0.3 mm, and a corresponding hyperopic shift of 4.00 diopters. Eyes in which the anterior IOL was placed in the ciliary sulcus showed no changes in refraction or combined IOL thickness. In these eyes, the anterior IOL had a higher mean decentration (0.49 mm +/- 0.20 [SD] after 12 months) than the posterior IOL (0.21 +/- 0.13 mm after 12 months). CONCLUSIONS: Piggyback IOL implantation with placement of 2 foldable IOLs in the capsular bag can be followed by a hyperopic shift that may be caused in part by displacement of the IOLs. Placement of the anterior IOL in the ciliary sulcus can lead to higher decentration of this IOL.
Adult↗
Correlation between clinical in vivo confocal microscopic and ex vivo histopathologic findings of Salzmann nodular degeneration.
PURPOSE: To report clinical, in vivo confocal microscopy and ex vivo histopathologic findings of Salzmann nodular degeneration (SND). METHODS: A 48-year-old woman with symptoms of ocular irritation and decreased visual acuity caused by SND in both eyes was treated by corneal scraping and phototherapeutic keratectomy (PTK). Slit-lamp biomicroscopy, in vivo confocal microscopy, ex vivo light microscopy, immunohistology, and corneal topography were performed. RESULTS: In vivo confocal microscopy showed an irregular network of highly reflective structures representing activated keratocytes, which could be seen by light microscopy and characterized immunohistologically as myofibroblasts. Unstructured areas with increased reflectivity correlated with irregularly arranged collagen fibers and hyaline deposits in the nodulus. Epithelial cells in vivo appeared atypically shaped and elongated. These observations were consistent with decreased thickness of the epithelium over the nodules showed by histopathology. Treatment led to a dramatic reduction of hyperopia. Two months after surgery, uncorrected visual acuity (UCVA) in the right eye was 20/32 and 20/20 with a refraction of -0.75 -0.75/0 degrees. UCVA in the left eye was 20/40 and 20/20 with a refraction of +0.50 -1.75/165 degrees. Corneal topography showed regular astigmatism. CONCLUSION: In vivo confocal microscopy confirmed the clinicopathologic findings of Salzmann's nodular degeneration. Observations by in vivo confocal microscopy were consistent with the histopathologic descriptions of SND.
Actins↗
Corneal trephination with the femtosecond laser.
PURPOSE: To evaluate the feasibility and cut quality of corneal trephination in human donor corneal tissue with the femtosecond laser. METHODS: Twelve human corneoscleral discs were inserted in an artificial anterior chamber. After corneal thickness measurement and tonometry, the cornea was mounted on a femtosecond laser (FEMTEC; 20/10 Perfect Vision, Heidelberg, Germany) through a contact lens (patient interface). Trephination was performed with diameters of 7.0, 7.5, 8.0, and 8.5 mm in 3 corneas each. The corneal button was removed from the corneoscleral disc in 2 of the 3 corneas in each case. The cut was not manipulated in the remaining corneas to enable histologic detection of possible tissue bridges. The cut edges were macroscopically and light-microscopically examined for quality. RESULTS: Corneal buttons and corneoscleral discs could be separated by blunt dissection in all cases. Tissue bridges were more common in thicker edematous corneas than in thinner ones. Both the macro- and microscopic examination disclosed smooth rectilinear cut margins with a perpendicular cut edge. CONCLUSION: This feasibility study shows that the femtosecond laser enables sufficient trephination of human donor corneas.
Cornea↗
Measuring contrast sensitivity under different lighting conditions: comparison of three tests.
PURPOSE: The purpose of this study was to evaluate three psychophysical tests for the measurement of contrast sensitivity (CS) and disability glare (DG) at different luminance levels. METHODS: In 60 eyes of 60 individuals (group 1: 20 healthy eyes of young individuals; group 2: 20 healthy eyes of elderly subjects; group 3: 20 eyes with nuclear cataract), CS with best correction was measured twice with the Frankfurt-Freiburg Contrast and Acuity Test System (FF-CATS) and the Functional Acuity Contrast Test (FACT, 1.5 cycles per degree [cpd]) at 167 cd/m2 and 0.167 cd/m2, and with the Pelli-Robson Chart (PRC) at 100 cd/m2 with and without glare. Repeatability of test and retest, and discriminative ability between the different subgroups, were assessed for CS values. RESULTS: Maximum CS values varied across tests. In all groups, highest CS values were obtained with the photopic FF-CATS. For FACT scores at 1.5 cpd, there was a ceiling effect for young subjects. CS scores obtained with the PRC were the lowest. The PRC had the best test-retest repeatability of all tests. Under mesopic conditions with glare, reliability was generally lower; the FF-CATS had the highest repeatability of the mesopic tests. The FF-CATS discriminated best between the different groups for all conditions. CONCLUSIONS: There are large discrepancies in the test results between CS testing methods, especially under different lighting conditions. Results from different CS tests are not interchangeable.
Adult↗
A standardized drawing scheme to document corneal changes following refractive corneal surgery.
PURPOSE: To present a systematic and standardized drawing scheme for unambiguous and reproducible documentation of corneal changes after incisional techniques, coagulative procedures, and lamellar and surface ablation excimer surgery. METHODS: Standardized symbols in five colors representing specific corneal conditions after incisional surgery (eg, radial keratotomy, astigmatic keratotomy), coagulative procedures (eg, laser thermokeratoplasty, conductive keratoplasty), surface ablation (eg, photorefractive keratectomy, laser subepithelial keratomileusis, epi-LASIK), and LASIK are used to record corneal changes in frontal and sectional views. RESULTS: Corneal changes following refractive corneal surgery were documented. CONCLUSIONS: The drawing scheme permits specific features to be followed in the clinic in a clear and unambiguous manner.
Cornea↗
Comment on the publication "Lamellar keratotomy to correct astigmatism in cataract surgery" by C. Wirbelauer et al.
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Astigmatism↗
Incidence of posterior vitreous detachment after laser in situ keratomileusis.
BACKGROUND: Vitreoretinal complications are rare in laser in situ keratomileusis (LASIK). Increase in intraocular pressure caused by intraoperative suction with subsequent deforming of the ocular globe and excimer laser shock during the ablation have been discussed as possible causes. The purpose of this study was to determine the effect of LASIK on the vitreous body. PATIENTS AND METHODS: In a prospective study we performed ocular ultrasonography (B scan) immediately before and 1 week after LASIK procedure in 103 myopic or myopic-astigmatic eyes (53 patients, mean age 36.3 years, 32 women, 21 men). In particular, the prevalence, localization, and extent of posterior vitreous detachment (PVD) were determined. RESULTS: The mean spherical equivalent was -4.85 D (range -1.25 to -8.38) and the mean anteroposterior ocular globe length was 25.13 mm (range 23.31-27.65). Ninety-five eyes (92.2%) had no PVD preoperatively. Nine eyes out of this group (seven patients, 9.5%) developed incomplete PVD as assessed 1 week postoperatively. Eight eyes (7.8%) had a partial PVD preoperatively and in only one eye was an extension of vitreous detachment observed after the surgery. None of the preoperatively measured parameters could predict the occurrence of PVD by LASIK. CONCLUSIONS: LASIK may in rare cases lead to new occurrence of PVD or extension of a previously existing partial PVD.
Adult↗
Tilt and decentration of three-piece foldable high-refractive silicone and hydrophobic acrylic intraocular lenses with 6-mm optics in an intraindividual comparison.
PURPOSE: Intraindividual comparison of tilt and decentration of three-piece foldable intraocular lenses (IOLs) with 6-mm optics and different edge design and material. DESIGN: Prospective randomized study. METHODS: Twenty-five patients with senile cataract (group I) received a foldable silicone, sharp optic edge IOL in one eye and a silicone, rounded optic edge IOL in the other eye. Group II (n = 28) received the foldable silicone, sharp optic edge IOL in one eye and an acrylate, sharp optic edge IOL in the other eye. Scheimpflug photography was performed after the procedure with an anterior eye segment analysis system. Tilt and decentration of the IOL optic were measured 1 week, 6 months, and 12 months after the procedure. RESULTS: In group I, the foldable silicone, sharp optic edge IOL showed a mean optic tilt of 3.03 +/- 1.79 degrees and an optic decentration of 0.24 +/- 0.13 mm; the silicone, rounded optic edge IOL showed a tilt of 3.26 +/- 1.69 degrees and a decentration of 0.23 +/- 0.13 mm. In group II, the foldable silicone, sharp optic edge IOL showed an average tilt of 2.34 +/- 1.81 degrees and a decentration of 0.29 +/- 0.21 mm after 12 months; the acrylate, sharp optic edge IOL had a tilt of 2.32 +/- 1.41 degrees and a decentration of 0.24 +/- 0.10 mm. There were no significant differences in either group. CONCLUSION: The examined IOLs showed a stable position regarding tilt and decentration in the first 12 postoperative months, independent of material and edge design. Slight deviations from the optical axis might affect the outcome in aspheric or multifocal IOLs.
Acrylic Resins↗