[Duration of Examination and Patient Comfort with a New Biometric Device, in Comparison to Three Established Devices]. / Untersuchungsdauer und Patientenkomfort eines neuen Biometriegeräts im Vergleich zu 3 etablierten Geräten.

PURPOSE: The aim of this study was to evaluate the duration of the preoperative examination and patient comfort in measurements with an Image Guided System (Verion, Alcon), which is used for the calculation and intraoperative alignment of toric intraocular lenses, in comparison to established keratometry devices. PATIENTS AND METHODS: In a prospective, monocentric, open, ethics committee controlled study, 150 eyes of 150 ophthalmologically healthy volunteers were examined by a single examiner. Three measurements were performed with the Verion Image Guided System and - for comparison - one measurement each with IOLMaster 500, Lenstar LS900 and Pentacam HR. The measurement time was recorded with a stopwatch. For the analysis, patients were divided into three age groups (young, middle, old). Patient comfort was assessed using a questionnaire, which focussed on grading the whole measurement, as well as brightness of light, head posture and subjective duration. RESULTS: The mean age of the volunteers was 40.5 years (18-78 years). The mean duration of measurement was as follows: first Verion measurement 54.0 ± 42.7 seconds (n = 149), second Verion measurement 42.0 ± 20.5 s (n = 144), third Verion measurement 44.7 ± 25.2 s (n = 143), IOLMaster 500 46.3 ± 22.4 s (n = 147), Lenstar LS900 46.6 ± 14.4 s (n = 146) and Pentacam HR 46.6 ± 25.5 s (n = 147). Only the first and second Verion measurements were statistically different (p < 0.01). There were no statistical differences between the age groups, with the single exception of young versus old with the Pentacam (p < 0.01). Subjective patient comfort (n = 143) was very high for all devices and rated as "not uncomfortable" or "slightly uncomfortable". CONCLUSION: The duration of the preoperative examination with the Verion Image Guided System is comparable to established keratometry devices. However, IOL calculation with the Verion requires measurement of axial length and anterior chamber depth with another biometric device, which requires additional time. No age dependent differences were found. The examination can be easily integrated into clinical routine and is well tolerated by patients.

[Influence of corneal pachymetric changes on functional results after cataract surgery]. / Einfluss der Hornhautdickenveränderung auf die funktionellen Ergebnisse nach Kataraktchirurgie.

BACKGROUND: In the early postoperative period following uncomplicated cataract surgery, the correlation of corrected distance visual acuity (CDVA) and the increase in corneal thickness and anterior chamber depth (ACD) are investigated. PATIENTS AND METHODS: A total of 54 cataract patients with a mean age of 70 ± 8.4 years were included in this prospective study. Surgery was carried out on one eye of each patient according to the study protocol. Refraction, CDVA and ACD were evaluated 1 day and 1 week postoperatively and compared with the pachymetry results measured with the Pentacam. RESULTS: The mean postoperative CDVA significantly improved from 0.31 ± 0.24 logMAR to 0.18 ± 0.22 logMAR after one day and up to 0.06 ± 0.13 logMAR one week after surgery (p < 0.05). The mean spherical equivalent was - 0.52 ± 0.69 D after one day and - 0.50 ± 0.82 D one week after surgery and showed only minimal differences compared to the mean target refraction of - 0.39 ± 0.70 D. Postoperative corneal thickness showed a significant increase compared to the preoperative results (p < 0.05) on both visits: the mean difference was 33.26 ± 50.20 µm (- 17 to 315 µm) on the first day and 20.22 ± 23.15 µm (- 10 to 99 µm) one week after surgery. Up to 7 days postoperatively the increase in corneal thickness and CDVA showed only moderate or no correlations (r = 0.465 vs. r = 0.072, respectively). Regarding pachymetry and ACD values, no or only low correlations were found. CONCLUSION: The significant increase in corneal thickness on the first and seventh day shows no to moderate correlation to the CDVA. Nevertheless, a good and early rehabilitation of visual acuity following uncomplicated cataract surgery is possible. Intraocular pressure measurement can lead to false high results due to an increase in corneal thickness.

[Postoperative Results after Implantation of a Toric, Aspheric Intraocular Lens]. / Postoperative Ergebnisse nach Implantation einer torischen, asphärischen Intraokularlinse.

PURPOSE: The purpose of this study was to evaluate the functional results and quality of vision after implantation of an aspheric, aberration-neutral, monofocal toric intraocular lens (IOL). PATIENTS AND METHODS: 18 eyes of 13 patients were enrolled in this prospective clinical study. The T-flex aspheric, aberration-free toric IOL (Rayner Intraocular Lenses Limited, U. K.) was implanted after femtosecond or standard phacoemulsification. Follow-up examinations were performed two to four months after surgery; these included subjective refraction, ETDRS uncorrected (UDVA) and corrected distance visual acuity (CDVA), wavefront analysis, measurements of stray light (C-Quant), and a questionnaire. RESULTS: Median UDVA was 0.06 logMAR (range: 0.30 to - 0.18 logMAR) postoperatively. Median CDVA increased from 0.20 logMAR (range: 0.64 to 0.00 logMAR) preoperatively to - 0.07 logMAR (range: 0.16 to - 0.26 logMAR) postoperatively. The median difference between achieved versus intended spherical equivalent was - 0.08 D (range: - 1.25 to + 0.65 D). Median subjective cylinder improved from - 2.00 D (range: - 6.50 to - 0.25 D) preoperatively to - 0.50 D (range: - 1.25 to 0.00 D) postoperatively. The median spherical aberrations (6 mm pupil size) were - 0.38 µm (range: - 0.69 to - 0.10 µm) postoperatively. Measurements of stray light (C-Quant) revealed a median value of 1.28 log(s) (range: 0.92 to 1.61 log[s]). CONCLUSION: The T-flex aspheric toric IOL provided beneficial and predictable functional results after surgery. The implantation of the T-flex is an effective method to correct a large range of corneal astigmatism.

[Functional results after implantation of an aspheric, aberration-neutral intraocular lens]. / Funktionelle Ergebnisse nach Implantation einer asphärischen, aberrationsneutralen Intraokularlinse.

PURPOSE: The aim of this study was to perform a clinical evaluation of the functional results and quality of vision after implantation of an aspheric, aberration-neutral, monofocal intraocular lens (IOL). PATIENTS AND METHODS: 47 eyes of 34 patients (median age: 68 years) with cataract were enrolled in this prospective clinical study that had Ethics Committee approval. The C-flex or Superflex aspheric IOL (Rayner, UK) was implanted after phacoemulsification. Follow-up examinations were performed two to four months after surgery including subjective refraction, ETDRS uncorrected (UDVA) and corrected distance visual acuity (CDVA), wavefront analysis, analysis of stray light (C-Quant), contrast sensitivity under different lighting conditions (F. A. C. T.) and a questionnaire. RESULTS: Two to four months after surgery, median UDVA was 0.08 logMAR (range: 0.64 to - 0.18 logMAR, n = 41). Median CDVA increased from 0.30 logMAR (range: 1.00 to - 0.02 logMAR) preoperatively to - 0.08 logMAR (range: 0.16 to - 0.22 logMAR) postoperatively (n = 47). Median difference between achieved vs. intended (Holladay 1-formula) spherical equivalent was + 0.06 D (range: - 1.06 to + 0.87 D). Median total HOA RMS (6 mm pupil size) was 0.66 µm (range: 0.41 to 1.19 µm). The median spherical aberrations were - 0.36 µm (range: - 0.70 to - 0.17 µm). Analysis of stray light (C-Quant) revealed a median value of 1.21 log(s) (range: 0.79 to 1.57 log[s]). CONCLUSION: The C-flex and Superflex aspheric IOLs provide good and predictable functional results. Patients are not negatively influenced by stray light and show slightly negative spherical aberrations.

[Intrastromal femtosecond laser-based presbyopia correction]. / Intrastromale Presbyopiekorrektur mittels Femtosekundenlaser.

The surgical correction of presbyopia is gaining more and more popularity in the field of refractive surgery. Besides intraocular treatment with multifocal or accommodative intraocular lenses more and more corneal laser approaches are being established. These are performed either with the Excimer laser as laser in situ keratomileusis (LASIK) or the femtosecond laser. The femtosecond laser treatment is done purely intrastromally without dissection of the epithelium and is characterized by an extremely low risk of infection and inflammation. The procedure leads to a central corneal steepening with more prolate shape and increase in depth of field. This leads to a better uncorrected near visual acuity, however, corrected distance visual acuity might be reduced due to these changes.

[Functional results after bilateral intrastromal femtosecond laser correction of presbyopia]. / Funktionelle Ergebnisse nach Korrektur der Presbyopie mittels bilateraler intrastromaler Femtosekundenlaserbehandlung.

PURPOSE: The purpose of this study was to evaluate the results of bilateral intrastromal femtosecond laser correction of presbyopia (INTRACOR). METHODS: In a prospective study 17 patients were enrolled who had previously received binocular treatment in a two-step approach. Postoperative (4-8 months) outcomes were compared with a matched control group who had undergone only unilateral surgery of the non-dominant eye (n = 17 patients, 24 months after surgery). RESULTS: The binocular distance corrected near visual acuity (DCNVA) showed the same median but lower scattering of values after bilateral treatment: 0.10 (median in logMAR) (0.30/- 0.10 min/max) (study) versus 0.10 (0.50/- 0.10) (control). In the study group, however, a higher loss of binocular corrected distance visual acuity (CDVA) was found: 23.5 %, 70.6 %, 5.9 % (0, - 1, - 2 lines) (study) versus 35.3 %, 64.7 % and 0 %, respectively (control). CONCLUSIONS: Regarding the reduced CDVA INTRACOR should initially only be performed in the non-dominant eye. In selected cases binocular treatment can improve DCNVA; however, careful risk-benefit assessment and informed consent are necessary.

[Effect of intrastromal correction of presbyopia with femtosecond laser (INTRACOR) on mesopic contrast sensitivity]. / Auswirkungen intrastromaler Presbyopiebehandlung mittels Femtosekundenlaser (INTRACOR) auf die mesopische Kontrastsensitivität.

BACKGROUND: The aim of this study was to examine the mesopic contrast sensitivity (CS) and glare sensitivity following intrastromal femtosecond laser correction of presbyopia (INTRACOR). PATIENTS AND METHODS: In this study 25 patients with slight hyperopia and presbyopia underwent femtosecond laser correction in the non-dominant eye. Mesotest II measurements (OCULUS Optikgeräte, Wetzlar, Germany) were performed with and without glare at each of four different contrast levels preoperatively as well as 3, 6, 12, 18 and 24 months postoperatively. Data were compared using the Wilcoxon-test with a level of significance of p < 0.05. RESULTS: After 24 months the median CS decreased from 1:2 to 1:2.7 without glare and from 1:23 to 0 with glare. Of all patients 36% showed loss in CS without and 52% with glare and CS did not show any statistically significant differences between the treated and the untreated fellow eyes after 12 and 24 months. Overall 9 out of 18 monocular treated patients showed no binocular night driving ability according to the recommendations of the German Society of Ophthalmology (DOG) and the Professional Association of German Ophthalmologists (BVA) 24 months following INTRACOR. CONCLUSIONS: INTRACOR can lead to a slight reduction of mesopic contrast sensitivity and an increase of glare sensitivity. Possible consequences on night driving ability should be discussed with the patients prior to treatment.

[Immunological graft rejection after autologous contralateral keratoplasty]. / Immunologisches Transplantatversagen nach autologer kontralateraler Keratoplastik.

Autologous keratoplasty from an amblyopic eye to the fellow oculus ultimus is a rarely used procedure. This is due to the relatively uncommon constellation of pathology. The following article reports the case of a graft rejection after autologous keratoplasty, while the homologous graft on the amblyopic fellow eye remained clear.

[Influence of different multifocal intraocular lens concepts on retinal stray light parameters]. / Einfluss verschiedener multifokaler Intraokularlinsenkonzepte auf den Streulichtparameter.

PURPOSE: Multifocal intraocular lenses (MIOL) are known to induce various photic phenomena depending on the optical principle. The aim of this study was to investigate the correlation between stray light measurements performed with the C-Quant (Oculus, Germany) and the results of a subjective patient questionnaire. PATIENTS AND METHODS: In this study three different MIOLs were compared: AMO ReZoom (refractive design, n=10), AMO ZM900 (diffractive design, n=10) and Oculentis Mplus (near segment design, n=10). Cataract and refractive patients were enrolled in the study. Functional results were evaluated at least 3 months postoperatively followed by stray light measurements and a subjective questionnaire. RESULTS: Surgery was performed for all patients without complications. The three groups were matched for age, IOL power and corrected distance visual acuity (CDVA). Significantly different stray light (median) values log(s) were found (Kruskal-Wallis test, p<0.05): 1.12 log (refractive), 1.13 log (segment) and 1.28 log (diffractive). The subjective questionnaire did not show differences in glare perception but refractive MIOL patients noticed more halos surrounding light sources than the diffractive and segment MIOL patients. CONCLUSIONS: Stray light and subjective photopic phenomena do not show any basic correlation. Measurements in patients with refractive MIOLs showed less stray light than near segment or diffractive MIOLs. However, refractive MIOLs induced more halos compared to the other groups analyzed.

[Agreement of subjective and objective refraction measurements following INTRACOR femtosecond laser treatment]. / Übereinstimmung subjektiver und objektiver Refraktionsmessungen nach INTRACOR-Femtosekundenlaser-Behandlung.

BACKGROUND: The goal of this study was to determine the accuracy of autorefraction measurements in patients after INTRACOR intrastromal femtosecond laser treatment of presbyopia by comparing the agreement between the subjective and objective refraction. PATIENTS AND METHODS: In this study the data of 19 patients with a mean age of 56.5±6.0 years following INTRACOR treatment were analyzed pre-operatively and 12 months postoperatively. Measurements of the subjective refraction and the results of the autorefractor Nidek-660A in miosis were compared. INTRACOR is a refractive intrastromal femtosecond laser treatment to correct presbyopia. During the procedure a series of five concentric rings in the central stroma are cut which cause a change in the curvature of the cornea. RESULTS: The differences in sphere and spherical equivalent between subjective refraction and autorefraction were not significant (t-test p>0.05 and Wilcoxon test p>0.05). Comparing the cylinder of the two measurements a significant difference (t-test p<0.05) was found. Focusing on the difference of the postoperative measurements of the subjective refraction and autorefraction a correlation (within ±0.5 D) of 89% in the sphere, 100% in cylinder and 68% in the spherical equivalent was detected. With one exception the differences in sphere, cylinder and the spherical equivalent were within ±1.25 D. In several patients the performance of the autorefraction with the Nidek-660A was somewhat complicated and the measures had to be repeated frequently. CONCLUSION: The agreement between subjective refraction and objective measurements of the Nidek-660A of patients following INTRACOR-treatment was good. However there was a significant difference in the cylinder values. Therefore thorough comparison of measurements obtained with the autorefractor and the subjective refraction is recommended.

[Precision of a new device for biometric measurements in pseudophakic eyes]. / Präzision eines neuen Biometriegeräts zur Messung pseudophaker Augen.

BACKGROUND: Biometric measurements and the knowledge of interrelationships of structures within the eye are especially mandatory for cataract and refractive surgery. As the number of pseudophakic patients steadily increases because cataract surgery becomes more easily available all over the world, exact biometry of eyes with crystalline lenses as well as pseudophakic eyes is gaining interest. In the present study we compared biometric measurements in pseudophakic eyes using a new optical low-coherence reflectometry (OLCR) device with results measured by the IOLMaster. PATIENTS AND METHODS: In this prospective study 140 pseudophakic eyes from 123 adult volunteers following uneventful cataract surgery and IOL implantation were examined at the International Vision Correction Research Centre (IVCRC) at the University of Heidelberg, Germany. The aim of this study was to evaluate a functional prototype of the new LENSTAR LS 900 (Haag-Streit)/ALLEGRO BioGraph (Wavelight) biometer and the IOLMaster V.5 (Carl Zeiss Meditec) and to compare axial length (AL) and keratometry measurements with those obtained by the IOLMaster. Additionally we investigated whether the LENSTAR/BioGraph can detect anterior chamber depth (ACD) and the effective lens position (ELP) of IOLs by OLCR in pseudophakic eyes. Patients with corneal or intraocular pathology and patients who had undergone other surgery in the investigated eye or whose cataract surgery dated back less than 4 weeks were not included in the study. Measurements were repeated with both devices as recommended by the manufacturers. Results were compared using Bland-Altman plots, Passing Bablok regression analysis and Pearson correlation calculations (MedCalc version 7.3.0.1). RESULTS: Valid axial length measurements were available in 137 eyes. The mean values were 23.75 mm for both devices (SD±2.08 with the IOLMaster, ±1.7 with the LENSTAR/BioGraph). The mean corneal radius (R) was 7.7±0.27 mm (IOLMaster) vs. 7.74±0.29 mm (LENSTAR/BioGraph). Valid ACD measurements with the LENSTAR/BioGraph were achieved in 30% of all cases. In 98.6% of the eyes in which ACD was analyzed manually a mean ACD of 4.73±0.53 mm was found. CONCLUSIONS: Both devices tested in this study showed a high correlation for AL and keratometry measurements. ACD measurements performed with the LENSTAR/BioGraph showed a measurable signal but the prototype calculated a value only in the minority (30%) of cases. This study showed that on the one hand the LENSTAR/BioGraph has the potential to be a reliable and useful machine for clinical everyday routine: This space and time-saving device includes several features which make it a patient and user friendly tool for diagnostics as well as screening. On the other hand we found that the software used in the prototype could be improved especially in order to identify IOLs and to measure reliable ACD values in pseudophakic patients. IOL surfaces did not generate sufficient interference signals in the LENSTAR/BioGraph and although the light reflected by the IOL surfaces was recognized by the device the software version used in this study did not generate numerical results for ACD.

[Effect of applanation tonometry on precision of biometry measurements]. / Einfluss der Applanationstonometrie auf die Präzision der Biometrie.

BACKGROUND: The aim of this study was to investigate the effect of applanation tonometry on the accuracy of biometric measurements and the reproducibility of keratometric measurements. PATIENTS AND METHODS: In this clinical prospective study a total of 16 patients were enrolled who presented for cataract surgery on 30 eyes. Biometry measurements were made using an IOLMaster optical biometer before and 10 min after standard Goldmann applanation tonometry. Local anesthesia was achieved by administering one drop of fluorescein-stained oxybuprocaine 0.4%. RESULTS: The mean absolute difference of intraocular lens power for emmetropia was 0.31 ± 0.33 D (range -1.56 to +1.12 D) and the mean standard deviation for R1 and R2 (n=28 eyes) was 0.014 ± 0.013 mm before and 0.024 ± 0.021 mm after tonometry. This difference was statistically significant (t-test, p<0.01). Moderate to severe irregular corneal surfaces were noted in some cases after tonometry. CONCLUSIONS: Local anesthesia and applanation tonometry reduced the accuracy of IOL power calculations with differences exceeding ± 1 D and the reliability of consecutive keratometry measurements decreased significantly. Therefore, it is advisable to perform biometry measurements at the very beginning of the preoperative examination.

[Hereditary hyperferritinemia cataract syndrome--the first family in Germany]. / Das hereditäre Hyperferritinämie-Katarakt-Syndrom--die erste Familie in Deutschland.

We report on a 23-year-old woman who presented with elevated serum ferritin values at our department. She had undergone cataract surgery at the age of 14 and her family pedigree showed hereditary autosomal-dominant cataract. The combination of isolated hyperferritinemia with autosomal-dominant hereditary cataract led to the diagnosis of the hereditary hyperferritinemia cataract syndrome (HHCS) which we now describe in a German family for the first time. HHCS was confirmed by detection of a causal mutation at position 32 within the iron responsive element (IRE) of L-ferritin leading to a guanine to adenine exchange and the pathognomonic star-shaped cataract. This mutation interrupts the post-transcriptional control of L-ferritin. It prevents binding of the iron regulatory protein 1 (IRP1) to the 5alpha untranslated region of L-ferritin resulting in uncontrolled L-ferritin synthesis and high serum ferritin levels independent of the body iron stores. Premature cataract is eventually caused by deposition of L-ferritin crystals in the lens of the eye. Our family shows the typical autosomal-dominant inheritance of HHCS over four generations affecting a total of 17 family members. The causal mutation, star-shaped cataract and typical laboratory configuration were confirmed in five patients. Thus, in gastroenterological practice, HHCS should be added as a differential diagnosis of hyperferritinemia in Germany. Importantly, patients with HHCS can be spared from invasive diagnostics such as liver biopsy.

Accuracy of a new partial coherence interferometry analyser for biometric measurements.

AIMS: Precise biometry is an essential preoperative measurement for refractive surgery as well as cataract surgery. A new device based on partial coherence interferometry technology was tested and evaluated for accuracy of measurements. METHODS: In a prospective study 200 eyes of 100 healthy phakic volunteers were examined with a functional prototype of the new ALLEGRO BioGraph (Wavelight AG)/LENSTAR LS 900 (Haag Streit AG) biometer and with the IOLMaster V.5 (Carl Zeiss Meditec AG). As recommended by the manufacturers, repeated measurements were performed with both devices and the results compared using Spearman correlation calculations (WinSTAT). RESULTS: Spearman correlation showed high correlations for axial length and keratometry measurements between the two devices tested. Anterior chamber depth, however, had a lower correlation between the two biometry devices. In addition, the mean values of the anterior chamber depth differed (IOLMaster 3.48 (SD 0.42) mm versus BioGraph/LENSTAR 3.64 (SD 0.26) mm); however, this difference was not statistically different (p>0.05, t test). CONCLUSION: The new biometer provided results that correlated very well with those of the IOLMaster. The ALLEGRO BioGraph/LENSTAR LS 900 is a precise device containing additional features that will be helpful tools for any cataract or refractive surgeon.

[Wavefront analysis in ophthalmologic diagnostics]. / Die Wellenfrontanalyse in der ophthalmologischen Diagnostik.

Modern aberrometry measures standard and so-called higher-order refractory aberrations. Ophthalmology and optometry use Zernike polynomials to describe aberrations of the retina and lens causing refractory errors. Aberrations of a higher order sometimes follow successful laser surgery, causing reduced vision and inducing patient dissatisfaction; enhanced wavefront data can help to avoid this. Aberrometry is used also for objective measurement of refractory changes. Wavefront techniques and their clinical application enable many options for understanding the delicate balance of eye optics. The future of refractive surgery lies in increasingly individualized treatment to suppress higher degrees of aberration and thus improve clinical results. Patients will continue placing greater demand on individualized intraocular lenses that correct higher-order aberrations.

[Localization and age relations of ocular aberrations]. / Lokalisation und altersabhängige Verteilung von Aberrationen des Auges.

BACKGROUND: The aim of this study was to analyze the distribution of total, corneal, and mainly internal human third- to sixth-order aberrations (HOA) and investigate possible correlations between wavefront errors and patient age. PATIENTS AND METHODS: For this study 140 eyes of 140 subjects (age range 17-77 years) were measured three times each using Nidek Optical Path Difference scan. Mean value and standard deviation for each Zernike polynomial was computed for a 5-mm pupil diameter, and six different age groups were formed. RESULTS: There was wide individual variation in the internal wavefront aberrations. The mean root-mean-square value for HOA was 0.4563 microm+/-0.296 microm. No positive correlation was found between Zernike polynomials and increasing age. In total spherical aberration however a significant difference was found between the 26-35-year and > or =56-year age groups (p=0.0002), as well as to internal and total coma (Z8) (p=0.0487 and p=0.0117, respectively). CONCLUSIONS: The internal, corneal, and total wavefront aberrations varied widely among patients. Some significant differences were found between the age groups. No correlation between age and the internal, corneal, or total aberrations was found.

[Scheimpflug and topography systems in ophthalmologic diagnostics]. / Scheimpflug- und Topographiesysteme in der ophthalmologischen Diagnostik.

Modern Ophthalmology is currently experiencing a boom in anterior segment analysis tools that can increasingly gather information with one short measurement. These systems are based e.g. on so-called Scheimpflug (Pentacam, Galilei), slitlamp, and Placido technologies (Orbscan IIz) and other measurement systems. They help in analyzing the cornea in detail, including calculation of corneal wavefront. In addition, morphological and anatomical parameters such as anterior chamber depth, pachymetry, chamber angle, and lens densitometry can be analyzed. That makes these new technologies of interest for refractive surgery as well as for screening procedures such as Glaucoma, Keratoconus and others. This survey focuses on the two models, Oculus Pentacam and B&L Orbscan IIz as representative of all the other systems, as they are the most successful machines in this field.

[Design and optical principles of multifocal lenses]. / Design und optische Prinzipien von Multifokallinsen.

Multifocal intraocular lenses (MIOLs) of different designs have been used for more than 20 years in modern cataract surgery. The first IOLs were either refractive 2-3-zone designs or of diffractive concept. All MIOL types, regardless of manufacturer, show reduced contrast sensitivity and increased glare for years. Nevertheless, even first-generation MIOL patients had very good functional results when patient selection, IOL calculation, and surgical techniques were appropriate. Today's gold standard is foldable, aspherical diffractive, or refractive MIOLS. Advancements in technology allow the possibility that MIOLs will be used for aphakia correction as well as presbyopia correction.

Intraocular lens power calculation using ray tracing following excimer laser surgery.

PURPOSE: To evaluate intraocular lens (IOL) power calculation using ray tracing in patients presenting with cataract after excimer laser surgery. METHODS: Ten eyes of seven consecutive patients who presented for cataract surgery following excimer laser treatment without any pre-refractive biometry data were enrolled in this prospective clinical study. Preoperatively, IOL power calculation was performed using a ray tracing software called OKULIX. Keratometry data (C-Scan) were imported and axial length (IOLMaster) was entered manually. Accuracy of IOL power calculation was investigated by subtracting attempted and achieved spherical equivalent. RESULTS: Mean spherical equivalent was -3.51+/-2.77 D (range -10.38 to -0.5 D) preoperatively and -1.01+/-1.08 D (range -2.5 to +0.75 D) postoperatively. Mean error was 0.31+/-0.84 D, mean absolute error was 0.74+/-0.46 D, and IOL calculation errors ranged from -1.39 to +1.47 D. A total of 40% of eyes were within +/-0.5 D, 70% within +/-1.0 D, and 100% within +/-1.5 D. Three eyes with corneal radii over 10 mm showed calculation errors exceeding +/-1.0 D. Mean best-corrected visual acuity increased from 20/60 to 20/30 postoperatively. CONCLUSIONS: IOL power calculation after excimer laser surgery can be difficult, especially when pre-refractive keratometry values are not available. In these cases, ray tracing combined with corneal topography measurements provides reliable and satisfactory postoperative results. However, it is advisable to be careful when calculating IOL power for eyes with corneal radii exceeding 10 mm because of slightly higher prediction errors.