[Duration of Examination and Patient Comfort with a New Biometric Device, in Comparison to Three Established Devices]

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]

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]

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]

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.

[Immunological graft rejection after autologous contralateral keratoplasty]

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.

[Precision of a new device for biometric measurements in pseudophakic eyes]

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.

[Hereditary hyperferritinemia cataract syndrome--the first family in Germany]

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]

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.

Genauigkeit der Linsenstärkenberechnung und Zentrierung einer asphärischen Intraokularlinse

BACKGROUND

Aspherical intraocular lenses (IOLs) are presumed to optimize the optical characteristics of IOLs. In order to profit from these characteristics, exact calculation of the IOL power and good centration of the lens are essential.

METHODS

In all, 43 eyes of 43 patients with an average age of 70.9+/-8.3 years underwent implantation of a Tecnis IOL (AMO, Ettlingen) after uneventful cataract surgery with topical anesthesia. IOL power calculation was performed using the Holladay, Haigis, and SRK II formulas. Spherical equivalent refraction and centration and position of the implanted IOLs were measured 6 months postoperatively. Centration of the IOL was analyzed using digital slit lamp photographs and an image analysis program.

RESULTS

Best corrected visual acuity (BCVA) increased from 0.47+/-0.25 (LogMAR) preoperatively to 0.1+/-0.11 6 months postoperatively (spherical equivalent +0.3+/-0.6 D). The intraindividual difference between target refraction and achieved postoperative refraction was 0.64+/-0.11 D for the Holladay formula, -0.21+/-0.11 D for the Haigis formula, and 0.97+/-0.15 D for the SRK II formula. The mean decentration of the IOL from the center of the corneal limbus was 0.4+/-0.1 mm.

CONCLUSIONS

For the aspherical Tecnis IOL very good postoperative functional results are reported, which are supported by an accurate calculation of the IOL power and a good centration of the IOL inside the capsular bag. In this study the Haigis formula showed the lowest difference between target refraction and achieved postoperative refraction.

Presbyopiekorrektur mittels Intraokularlinsen

Modern cataract surgery has advanced tremendously over the past 20 years. Improved surgical techniques, as well as improved implant materials and designs, have enlarged patient profiles and indications not only for cataract surgery, but also for refractive lens exchange surgery. This has also created much higher patient expectations. The loss of accommodation is a loss of quality of life for presbyopic and especially young pseudophakic patients. Multifocal intraocular lenses (MIOL) have been implanted since 1986, starting with 2-3 zone refractive and diffractive designs. Due to the surgical techniques available at that time, MIOL decentration and surgically induced astigmatism were possible complications. In addition, reduced contrast perception and increased glare were common problems of MIOL because of their optical principles. New developments in this field in recent years such as the folding, multizonal, progressive refractive MIOL and aspheric diffractive MIOL in combination with improved surgical techniques have overcome those initial problems. Therefore, modern MIOL (and in the future also accommodative IOL) can be considered not only for the correction of aphakia but also for refractive purposes.

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.

Quantitative Nachstarevaluierung von Acrylat- und Silikonintraokularlinsen mit scharfem Kantendesign

BACKGROUND

At the Department of Ophthalmology, Heidelberg, Germany, posterior capsule opacification (PCO) of a silicone and an acrylic intraocular lens (IOL) with a sharp optic edge design was evaluated.

PATIENTS AND METHODS

In a prospective study either the AMO ClariFlex silicone IOL or the Sensar AR40e hydrophobic acrylic IOL were implanted in 47 patients following uneventful phacoemulsification. Mean patient age was 76.2+/-7.8 (ClariFlex) and 73.4+/-12.9 years (AR40e), respectively. The mean follow-up time was 19.7+/-5.34 in the ClariFlex and 21.9+/-1.89 months in the AR40e group. PCO development was evaluated postoperatively using the EPCO 2000 analysis software (scale 0-4). Areas of interest were the total IOL optic, the central 3-mm zone as well as the capsulorhexis.

RESULTS

In both groups, all patients achieved a BCVA of 20/32 (AR40e) and 20/25 (ClariFlex), respectively. There was a very low incidence of PCO development with a mean EPCO score of 0.07+/-0.2 (ClariFlex and 0.15+/-0.2 (AR40e). Within the 3-mm zone and the capsulorhexis, there was a tendency for even lower EPCO scores in both groups. We calculated a statistically significant difference for the two lens materials for all investigated IOL areas (Wilcoxon's test, p<0.05).

CONCLUSION

Both IOLs with a sharp edge design showed good functional results, a stable position in the capsular bag as well as a low incidence of PCO development. However, the silicone IOL showed statistically significantly lower PCO scores.