Thomas Kasper

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 (Z40) 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 Z40 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 Z40 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.

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/m2) was measured with the observer‐independent Frankfurt‐Freiburg Contrast and Acuity Test System (FF‐CATS) and high‐mesopic HCVA and LCVA (8 cd/m2) were measured with Early Treatment Diabetic Retinopathy Study charts. CS was assessed with the FF‐CATS under photopic (167 cd/m2), high‐mesopic (1.67 cd/m2), and low‐mesopic (0.167 cd/m2) luminance conditions with and without glare. For each individual eye, higher‐order wavefront aberrations were reconstructed for a physiological mesopic pupil diameter. Intraindividual differences (Δi) in visual acuity, contrast sensitivity, and higher‐order aberrations (HOAs) were calculated, and the influence of age and Δi HOA on Δi 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 (Z40) was significantly lower in the Tecnis group (P<.001). For all parameters studied except Z40, the Δi values were distributed around zero. Multiple regression analysis showed only a partial influence of Δi Z40 on Δi logCS (adjusted R2 = 0.49) but did not show any influence of age, coma‐like aberration, or residual HOA. CONCLUSIONS: Although Z40 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 Z40 difference was too low to have an effect on contrast sensitivity.

Correlation of infrared pupillometers and CCD-camera imaging from aberrometry and videokeratography for determining scotopic pupil size

Purpose: To compare 2 infrared pupillometers with a videokeratographer and 2 aberrometers for the determination of scotopic pupil size. Setting: Department of Ophthalmology, Johann Wolfgang Goethe‐University, Frankfurt am Main, Germany. Methods: The pupil diameter was measured in 100 eyes of 51 patients after 2 minutes of dark adaptation using the following devices: digital infrared pupillometer (Procyon Instruments Ltd.), handheld infrared pupillometer (Colvard) (Oasis Medical), Zywave® aberrometer (Bausch & Lomb), Wasca aberrometer (Asclepion‐Meditec‐Zeiss), and Orbscan® II topography system (Bausch & Lomb Surgical). Measurements taken with the Procyon pupillometer were considered reference values for comparison with the other devices. Statistical evaluation was performed using the Bland‐Altmann method for comparison of measurement techniques. Results: The mean pupil size was 6.10 mm ± 0.86 (SD) with the Procyon pupil‐ lometer, 5.68 ± 1.07 mm with the Colvard pupillometer, 5.91 ± 1.01 mm with the Zywave aberrometer with the fixating target turned off, 5.09 ± 1.14 mm with the Zywave aberrometer with the fixating target turned on, 5.59 ± 0.99 mm with the Wasca aberrometer, and 3.75 ± 0.67 mm with the Orbscan topographer. The limits of agreement were smallest for measurements between Procyon and Colvard and largest for measurements between Procyon and Orbscan. The sign test revealed statistically significant differences for all devices compared with the Procyon pupillometer (P<.001 in all cases) except the Zywave aberrometer with the fixating target turned off (P = .13). Conclusions: The Zywave wavefront sensor with the fixating target turned off using the study settings and light conditions provided measurements of scotopic pupil diameter that were closest to the reference values (Procyon). With the other devices (Colvard pupillometer, Zywave aberrometer with the fixating target switched on, Wasca aberrometer, and Orbscan topographer), the difference was statistically significant.

Intraocular lenses for the correction of refraction errors. Part II. Phakic posterior chamber lenses and refractive lens exchange with posterior chamber lens implantation

ZusammenfassungIm vorliegenden Übersichtsartikel wird der derzeitige Stand der Intraokularlinsenchirurgie zur Korrektur von Refraktionsfehlern dargestellt. Man unterscheidet zwischen additiver Chirurgie mit Kunstlinsenimplantation ohne Extraktion der kristallinen Linse [phake Intraokularlinse (PIOL)] und der Entfernung der natürlichen Linse mit Implantation einer Kunstlinse [refraktiver Linsenaustausch (RLA)]. Die phaken Intraokularlinsen (PIOL) werden in kammerwinkelgestütze und irisgetragene Vorderkammerlinsen sowie sulkusfixierte Hinterkammerlinsen unterteilt. Die Implantation der phaken IOL hat sich als effektives, sicheres, vorhersagbares und stabiles Verfahren zur Korrektur von höheren Ametropien erwiesen. Komplikationen sind selten und zwischen den 3 verschiedenen PIOL-Typen unterschiedlich, bei den Hinterkammerlinsen handelt es sich um Kataraktentwicklung und Pigmentdispersion. Der refraktive Linsenaustausch (RLA) wird bevorzugt dann bei hohen Ametropien eingesetzt, wenn keine Akkommmodationsleistung der natürlichen Linse mehr zu erwarten ist. Zu den Komplikationsmöglichkeiten des myopen RLA gehören die Netzhautablösung, zu denen des hyperopen RLA operative Schwierigkeiten bedingt durch das kurze Vordersegment.AbstractIn this overview, the current status of intraocular lens surgery to correct refractive error is reviewed. The interventions are divided into additive surgery with intraocular lens implantation without extraction of the crystalline lens (phakic intraocular lens, PIOL) or removal of the crystalline lens with implantation of an IOL (refractive lens exchange, RLE). Phakic IOLs are constructed as angle-supported or iris-fixated anterior chamber lenses and posterior chamber lenses which are fixated in the ciliary sulcus. The implantation of phakic IOLs has been demonstrated to be an effective, safe, predictable and stable procedure to correct higher refractive errors. Complications are rare and differ for the three types of PIOL; for posterior chamber lenses these are mainly cataract formation and pigment dispersion. RLE is preferable in cases of high ametropia in which the natural lens has lost its accommodative effect. The main complications for myopic RLA include retinal detachment, while hyperopic refractive lens exchange may be associated with surgical problems in the narrower anterior eye segment.

Quality of Vision After Refractive Surgery

After inventing, evaluating and perfecting refractive surgical procedures in recent years, one of the current efforts is to focus on “quality of vision” after various surgical interventions. The number of surgical procedures to correct refractive errors is steadily increasing, old procedures are replaced by newer, mostly better ones, the complication rate is decreasing, and the results of each of the established procedures are improving with more experience, better technology and scientific evaluation. Success or failure of refractive procedures, defined by criteria like safety, efficacy, stability and predictability [13] is based on Snellen acuity. However, some patients present with anatomically perfect results and excellent visual outcome with respect to these criteria measured in Snellen acuity,but complain of visual disturbances like decreased contrast, different colour perception, glare, halos or simply “bad vision”. In some cases the problem can be explained, e.g. by residual astigmatism or a decentred ablation zone in excimer surgery or the optic diameter of a phakic intraocular lens implant on halo perception, in other cases an immediate answer is not found. On the contrary, in retrospect there should have been problems (6mm ablation zone for LASIK with 7-mm scotopic pupil size diameter) that fortunately have never occurred. Therefore determining the outcome seems to be more complex. Why do only some patients complain? Are some complaints associated with simple residual refractive error or are there other much more sophisticated reasons for visual disturbances yet unknown to the patients [14]? The present chapter gives an overview of how quality of vision could be defined and determined and summarises typical disturbances which are known to date.

Selecting Phakic Intraocular Lenses for the Correction of Refractive Errors

Detailed and exact preoperative examinations are required to secure postoperative results that are highly satisfactory for the patients. The most important measurements are refraction, corneal topography, biometry of the anterior and posterior chamber, as well as endothelial cell density.