Search

Purpose To prospectively study the feasibility of femtosecond lenticule extraction (FLE), a new method of refractive correction. Setting Department of Ophthalmology, Philipps University of Marburg and Helios Clinic, Erfurt, Germany. Methods A flap and a lenticule of intrastromal corneal tissue were simultaneously cut with a VisuMax femtosecond laser system. Next, the lenticule was manually removed and the flap repositioned. The target refraction in all cases was −0.75 diopter (D). Results All 10 myopic eyes in the initial treatment group completed the final 6-month follow-up. The mean patient age was 39 years. The mean spherical equivalent (SE) was −4.73 ± 1.48 (SD) preoperatively and −0.33 ± 0.61 D 6 months postoperatively. Ninety percent of eyes were within ±1.00 D and 40% were within ±0.50 D of the intended correction. No eye lost 2 or more Snellen lines. Corneal topography showed large, prolate optical zones. Aberrometry showed no significant induction of higher-order aberrations. On a standardized questionnaire, all patients said they were very satisfied with the results. Conclusions Preliminary results indicate that FLE is a promising new corneal refractive procedure to correct myopia.

OBJECTIVE—Stimulation of the retina with flickering light increases retinal vessel diameters in humans. Nitric oxide is a mediator of the retinal vasodilation to flicker. The reduction of vasodilation is considered an endothelial dysfunction. We investigated the response of retinal vessels to flickering light in diabetic patients in different stages of diabetic retinopathy. RESEARCH DESIGN AND METHODS—We studied 53 healthy volunteers, 68 type 1 diabetic patients, and 172 type 2 diabetic patients. The diameter of retinal vessels was measured continuously online with the Dynamic Vessel Analyzer (DVA). Diabetic retinopathy was classified using Early Treatment Diabetic Retinopathy Study criteria. Changes in vasodilation are expressed as percent change over baseline values. RESULTS—After adjustments for age, sex, and antihypertensive treatment, the response of retinal arterioles to diffuse luminance flicker was significantly diminished in patients with type 1 diabetes compared with healthy volunteers. The vasodilation of retinal arterioles and venules decreased continuously with increasing stages of diabetic retinopathy. The retinal arterial diameter change was 3.6 ± 2.1% in the control group, 2.6 ± 2.5% in the no diabetic retinopathy group, 2.0 ± 2.7% in the mild nonproliferative diabetic retinopathy (NPDR) group, 1.6 ± 2.2% in the moderate NPDR group, 1.8 ± 1.9% in severe NPDR group, and 0.8 ± 1.6% in proliferative diabetic retinopathy group. CONCLUSIONS—Flicker responses of retinal vessels are abnormally reduced in diabetic patients. This decreased response deteriorated with increasing stages of retinopathy. The response was already reduced before clinical appearance of retinopathy. The noninvasive testing of retinal autoregulation with DVA might prove to be of value in early detection of diabetic vessel pathological changes.

Purpose To investigate whether the advanced glycation end-products (AGEs) pentosidine, Ne-(carboxymethyl)lysine (CML), and imidazolone are present in the aqueous of cataract patients and how AGE levels correlate to cataract type or the diabetic condition of the patient. Setting Departments of Ophthalmology and Internal Medicine, University of Jena, Jena, Germany. Methods Aqueous and serum samples from 77 cataractous patients (33 nondiabetics, 44 diabetics; 14 with dense posterior, 63 with nuclear cataracts) were investigated. The mean age of the patients was 69 years ± 14 (SD). The aqueous protein concentration was examined using a laser flare–cell meter. In the samples, pentosidine was measured by high-performance liquid chromatography and CML using a competitive enzyme-linked immunosorbent assay. Western blot analysis was used to detect imidazolone, pentosidine, and CML in the aqueous. Results The aqueous samples contained CML, pentosidine, or imidazolone. These AGEs occurred mainly bound to albumin. Significant correlations existed between serum pentosidine and aqueous CML and flare levels as well as between serum and aqueous CML. Patients with nuclear cataract had insignificantly higher pentosidine and CML levels than patients with posterior cataract, whereas the flare was significantly higher. No significant differences were found between the aqueous AGE levels in nondiabetic and diabetic patients. Conclusions The aqueous of cataractous eyes contained the AGEs CML, pentosidine, and imidazolone. All 3 AGEs occurred mainly albumin-bound, providing evidence they may originate from the blood. Further investigation is needed to determine the relevance of aqueous AGEs in cataractogenesis.

Dear editor,We thank Zhang and Hoffman for their comments on ourarticle [1]. In their letter, the authors discussed the relation-ship between femtosecond laser parameters and quality ofthe corneal stromal bed surface.The authors mentioned that normative standard settingsfor laser parameters like laser pulse energy and spot/lineseparation are warranted to obtain a better quality of thecorneal stromal bed and for a possibly better patient out-come. We think that the manufacturers of the laser systemsare recommending parameter ranges rather than single val-ues not only because such standard laser settings are notavailable, but the surface quality of the stromal bed and thevisual outcome also depend on the specific working proce-dure with regard to different surgeons and different surgicalinstruments used [2–5].For the ReLEx® procedure with the Carl Zeiss Meditecfemtosecond laser system VisuMax®, spot- and track dis-tances of 3 μm are recommended and the surgeon shouldonly adjust the laser pulse energy settings slightly to opti-mize tissue separation and surface quality. The ability tomake parameter adjustments allows the surgeon to adapt thelaser procedure to his or her individual needs and helps tooptimize patient outcome.We agree that if the spot- and track distance were toosmall or the pulse energy was too high, the applied bubbleswould coalesce, which would make the manual surgery a bitmore difficult [6].However, there is no need for frequent adjustment ofthese parameters with the femtosecond laser system weuse. Nevertheless, some colleagues who like to make flapswith a different thickness may find that they could use thesame spot separation but like lower or higher pulse energiesto obtain optimum tissue separation (unpublished personalcommunication). This is the reason why we think that nor-mative standard settings are not useful for femtosecond lasertreatments.Lastly, we like to notify that we are able to achievesmooth stromal beds and good visual outcome by varyingthe parameters of our femtosecond laser system and so weare happy to be able to change the parameters within acertain range to adapt these settings to our individualrequirements [1, 3, 4, 7].

Purpose: To describe a morphological scoring system of posterior capsule opacification (PCO) that is not based on visual acuity testing. Setting: Department of Ophthalmology, University of Heidelberg, Germany. Methods: Following dilation of the pupil, standardized photographs of the pseudophakic anterior segments were obtained using a photo slitlamp. Posterior capsule opacification was scored by evaluating retroillumination photographs. The individual PCO score was calculated by multiplying the density of the opacification (graded from 0 to 4) by the fraction of capsule area involved behind the intraocular lens (IOL) optic. To evaluate the reliability of the morphological scoring system, six observers examined photographs of five eyes each (Experiment A, interindividual reliability). The same observer scored the PCO in three eyes on five different days (Experiment B, intraindividual reliability). Results: Morphological PCO scores were very reliable. With PCO scoring from 0 to 4, the interindividual reliability showed standard deviations between 0.08 and 0.25. The intraindividual reliability showed standard deviations between 0.06 and 0.19 of the mean individual PCO scores. Standard deviation was 0.12 when different photographs of the same eye were scored. Conclusion: The morphological scoring system evaluates the entire area behind the IOL optic and thus includes a larger area of the posterior capsule than does visual acuity testing. The method revealed high reliability and insignificant investigatordependent variations. When using a standardized photographic setup, systematic errors by the photographic technique were not relevant. This method may be an important tool to accurately test for differences in PCO formation with various IOL styles and surgical methods.

Visualization of renal autoregulation in the split hydronephrotic kidney of rats. The autoregulatory ability of the renal vascular system in the split hydronephrotic kidney was quantitated with intravital microscopy. The luminal diameters of the arcuate and interlobular arteries as well as the afferent and efferent arterioles were measured. Glomerular blood flow was determined by the dual slit technique. In the first series of experiments, the renal perfusion pressure was reduced by graded clamping of the abdominal aorta. Pressure reduction from 118mm Hg to 95mm Hg induced dilation of all preglomerular vessels except for the distal afferent arteriole; there was no change in the efferent arteriole and the blood flow was maintained. Further pressure reductions to 71 and 43mm Hg caused additional dilations of the preglomerular vessels, a marginal reduction in diameter of proximal efferent arterioles and flow reductions by 15% and 41%, respectively. In the second series, systemic blood pressure was increased by continuous i.v. infusions of norepinephrine (NE). NE constricted pre- and postglomerular vessels except for the distal afferent arteriole; glomerular flow was decreased. Reduction of renal perfusion pressure during NE infusion to the preinfusion value did not diminish glomerular blood flow, but reduced the constrictor response to NE in preglomerular vessels. In a third series of experiments we examined the effect of atrial natriuretic factor (ANF) on renal autoregulation. Addition of ANF (10−9 to 10−7M) to the renal bath induced a dose-dependent dilation of all preglomerular vessels and a constriction of the efferent arteriole. Pressure reduction from 120 to 95mm Hg resulted in a further preglomerular vasodilation. These experiments demonstrate that autoregulation is mediated primarily by diameter changes in all preglomerular vessels excluding the distal segment of the afferent arteriole. Further, these data suggest that ANF induced dilation of preglomerular vessels does not impair the myogenic response of these vessels.

Purpose To estimate the repeatability of biometric parameters obtained with a new swept-source biometer and to compare the agreement with that of partial coherence interferometry (PCI) and optical low-coherence reflectometry (OLCR). Setting Department of Ophthalmology, Helios Hospital Erfurt, Erfurt, Julius-Maximilians University, Wurzburg, and Philipps University, Marburg, Germany. Design Prospective comparative multicenter clinical study. Methods Biometry was taken with the use of 3 different biometers: the IOLMaster 700 swept-source biometer, the PCI-based IOLMaster 500, and the OCLR-based Lenstar LS 900. Axial length (AL), anterior chamber depth (ACD), and spherical equivalent (SE) were compared between swept-source and PCI biometry and central corneal thickness (CCT) and lens thickness (LT) between swept-source and OLCR biometry. The repeatability of swept-source biometry was evaluated on the basis of 3 measurements captured for each patient. Results One hundred twenty cataract eyes were included in the study. The mean difference between swept-source and PCI biometry for AL, ACD, and SE measurements was 4 μm ± 25 (SD), 17 ± 122 μm, and −0.001 ± 0.19 diopter (D), respectively. The mean difference between swept-source and OLCR biometry for LT and CCT measurements was 21 ± 122 μm and 0.15 ± 4.51 μm, respectively. Differences between swept-source biometry and the other devices distributed around zero without statistical significance. The standard deviation of repeatability for AL, ACD, LT, CCT, and SE was 8.8 μm, 9.8 μm, 2.3 μm, 19.5 μm, and 0.1 D, respectively. Conclusions Swept-source biometry showed high repeatability performance for all biometric parameters. The agreement of AL, ACD, and SE between swept-source and PCI biometry as well as that of LT and CCT between swept-source and OLCR biometry was excellent. It remains to be validated whether high repeatability shown by swept-source biometry will result in better postoperative refractive outcomes. Financial Disclosure Drs. Blum and Sekundo are members of the Scientific Advisory Board of Carl Zeiss Meditec AG. Drs. Peter and Buhren are employees of Carl Zeiss Meditec AG.