David Kuerten

Evaluation of early anatomical changes following canaloplasty with anterior segment spectral-domain optical coherence tomography and ultrasound biomicroscopy

To analyse structural changes in conjunctiva, sclera and Schlemms canal (SC) following canaloplasty with optical coherence tomography (AS‐OCT) and ultrasound biomicroscopy (UBM).

Long term effect of trabeculectomy on retrobulbar haemodynamics in glaucoma

Previous reports showed increased flow velocities in retrobulbar vessels after glaucoma surgery in the first weeks. Colour Doppler imaging was performed to investigate the long‐term effects of trabeculectomy on retrobulbar haemodynamics in patients with primary open–angle glaucoma (POAG).

Comparison of Gebauer SLc and Moria CBm Carriazo-Barraquer ALK Microkeratomes for Descemet’s Stripping Automated Endothelial Keratoplasty Preparation

ABSTRACT Purpose: We compared the hand-guided Moria Carriazo-Barraquer (CBm) microkeratome with the fully automatic SLc microkeratome for Descemet’s stripping automated endothelial keratoplasty (DSAEK)-lamella preparation and storage, vis-à-vis accuracy, endothelial cell loss (ECL), and lamellar surface roughness (LSR). Methods: A total of 18 human corneas were dissected with both the 300 μm CBm multi-use (n = 9) and the 300 µm SLc (n = 9) single-use heads, after which they were incubated for 6 d in a 5% dextran medium. Before preparation (0 h) and 1, 24, and 144 h after dissection, ECL and corneal thickness (CT) were measured by ultrasound pachymetry (USP) and optical coherence tomography (OCT). LSR was assessed by scanning electron microscopy (SEM) and evaluated by three masked observers. Results: Prior to cutting, CTs did not differ significantly between OCT or USP measurements, with a high correlation between the two modalities (r2 = 0.94, p < 0.0001). One hour after preparation the anterior lamella showed a significantly higher dissection depth with the CBm (429.4 ± 21.8 µm) than the SLc (311.7 ± 54.8 µm, p = 0.0006), with the variance of the SLc system showing a trend towards higher values (p = 0.07). Anterior and posterior lamellae swelled significantly in the subsequent culture period. Both groups showed a significant ECL 1 h after preparation (p < 0.0001) with no significant difference between the systems (1 h: p = 0.44; CBm: − 9.4%, SLc: −11.7%), which stabilized over 144 h (144 h CBm: −13.9%, 144 h SLc: −10.3%). LSR did not differ significantly between both systems (p = 0.60). Conclusions: The SLc system agrees more with the designated cutting depth than the CBm. The dissection produced a comparable LSR and a ∼10% ECL independently of the system. Further incubation of the prepared lamellae led to a swelling, but no further ECL.

Three-Year Follow-Up of Trabeculectomy with 5-Fluorouracil

Purpose: To evaluate the long-term outcome of trabeculectomy with intra- and postoperative 5-fluorouracil (5-FU) application in glaucoma. Methods: Eighty-six patients with glaucoma planned for primary trabeculectomy with 5-FU and a minimum follow-up of 3 years were retrospectively analyzed. Success rates, postsurgical 5-FU injections, needling procedures, and complications were analyzed. Results: Mean intraocular pressure (IOP) decreased from 27.2 ± 6.7 to 13.2 ± 4.2 mm Hg at 1 year and 13.8 ± 3.7 mm Hg at the 3-year follow-up. The complete success rates (no IOP-lowering medication) were 83, 79, 73, and 45% at 1 year for IOP ≤21, ≤18, ≤16, and ≤12 mm Hg, respectively, and 64, 59, 56, and 20% for these criteria at 3 years. The average number of medications decreased from preoperatively 2.9 ± 1.4 to 0.2 ± 0.5 at 1 year and 0.7 ± 1.1 at 3 years. During the first 6 months, subconjunctival 5-FU injections were performed in 49 cases. Eleven patients underwent bleb needling during the first 6 months and 13 patients underwent the procedure between the 6th month and the 3rd year. Malignant glaucoma and bleb-related endophthalmitis occurred in 1 patient each. Conclusions: Trabeculectomy with 5-FU is an efficient surgical procedure for glaucoma treatment when combined with intensified postsurgical care.

The effect of air, SF6 and C3F8 on immortalized human corneal endothelial cells

While anterior chamber air bubbles aid attachment during posterior lamellar surgery only for few days, these periods can be prolonged with gases in non‐expanding concentrations. To test the effects of different gas compositions on immortalized human corneal endothelial cells (HCEC‐12), we utilized Transwell inserts with semipermeable membranes as an artificial anterior chamber model.

Gebauer SLc Original and Moria One‐Use Plus automated microkeratomes for ultrathin Descemet's stripping automated endothelial keratoplasty preparation

We compared the SLc Original (SLc) and One‐Use Plus (OUP) microkeratomes for ultrathin Descemets stripping automated endothelial keratoplasty (DSAEK) lamella preparation and storage, vis‐à‐vis accuracy, endothelial cell loss (ECL) and lamellar surface roughness (LSR).

Blood Pressure and Heart Rate Variability in Primary Open-Angle Glaucoma and Normal Tension Glaucoma

ABSTRACT Purpose: Vascular dysfunction and ischemia are believed to play an important part in the pathogenesis of glaucoma and especially of normal tension glaucoma (NTG). The aim of the present study was to analyze the blood pressure (BP) and heart rate variability patterns in patients with primary open-angle glaucoma (POAG) and NTG compared with controls. Methods: In total, 37 patients with POAG, 27 patients with NTG, and 82 control subjects were included in a prospective clinical validation study. Continuous BP and heart rate were simultaneously recorded over 30 min (Glaucoscreen, aviant GmbH, Jena, Germany) under resting conditions. Time series of heart rate, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were extracted and analyzed calculating univariate linear (time domain, frequency domain), nonlinear (symbolic dynamics), and bivariate (joint symbolic dynamics) indices. Results: Overall, 12 parameters could be identified that were significantly different when comparing POAG patients and controls, whereas 80 parameters were significantly different in NTG patients compared with controls. The optimum set consisting of three indices showed a sensitivity of 81.5% at a specificity of 86.6% for NTG patients compared with a sensitivity of 62.2% at a specificity of 82.9% for POAG patients. Conclusions: Alterations in BP variability and coupling with heart rate suggest impaired patterns of autonomic cardiovascular regulation in glaucoma patients especially in patients with NTG.

Acute Effect of Hypervolemic Hemodilution on Retrobulbar Hemodynamics in Anterior Ischemic Optic Neuropathy

Purpose Ischemic ocular disorders may be treated by hypervolemic hemodilution. The presumed therapeutic benefit is based on a volume effect and improved rheological factors. The aim was to investigate the acute effect of intravenous hydroxyethyl starch on retrobulbar hemodynamics in patients with nonarteritic anterior ischemic optic neuropathy (NAION). Methods 24 patients with acute NAION were included. Retrobulbar hemodynamics were measured using color Doppler imaging before and 15 min after intravenous infusion of 250 cc 10% hydroxyethyl starch (HES). Peak systolic velocity (PSV), end diastolic velocity (EDV), and Pourcelots resistive index (RI) were measured in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (PCAs). Results After infusion of HES blood flow velocities significantly increased in the CRA (PSV from 7.53 ± 2.33 to 8.32 ± 2.51  (p < 0.001); EDV from 2.16 ± 0.56 to 2.34 ± 0.55  (p < 0.05)) and in the PCAs (PSV from 7.18 ± 1.62 to 7.56 ± 1.55  (p < 0.01); EDV from 2.48 ± 0.55 to 2.66 ± 0.6 cm/sec (p < 0.01)). The RI of all retrobulbar vessels remained unaffected. Blood pressure and heart rate remained unchanged. Conclusions Hypervolemic hemodilution has an acute effect on blood flow velocities in the CRA and PCAs in NAION patients. Increased blood flow in the arteries supplying the optic nerve head may lead to a better perfusion in NAION patients. This trial is registered with DRKS00012603.

Evaluation of Long-term Anatomic Changes Following Canaloplasty With Anterior Segment Spectral-domain Optical Coherence Tomography and Ultrasound Biomicroscopy

Background: To analyze long-term structural changes in conjunctiva, sclera and Schlemm canal (SC) with anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM) following uncomplicated canaloplasty. Materials and Methods: Fifteen patients with planned canaloplasty and no intraoperative complications were included in this prospective study. AS-OCT images were acquired at 1, 3, 6 months and at a long-term time point (20±4.9 mo) postsurgery. UBM images were acquired at 3, 6 months and long-term after canaloplasty. The surgical site was evaluated for the presence of SC, transscleral filtration, a scleral lake, and the visibility of intra-Schlemm sutures. The SC’s height and width were measured at the 3 and 9 o’clock limbus position. Results: Following canaloplasty, the intraocular pressure was successfully reduced from 23.43±5.52 to 12.6±1.78 mm Hg (P<0.0001) at the final control visit. Topical medication was reduced from 2.9±1.1 to 0.4±0.6 over the same period. SC’s increase in height was higher than that in width at the last visit (height: +351%, P=0.0004, width: +144%, P=0.002). With the UBM the SC was easily identifiable by the reflection of the tractions sutures in 75% of the patients at the last visit. Transscleral filtration was detectable in 42% of the patients at the last visit using AS-OCT and a scleral lake was still detectable by OCT in 25% of the patients and even in 42% of the patients by UBM. Conclusions: Persisting anatomic changes of SC, a transscleral filtration and a scleral lake can be recorded by AS-OCT and UBM long-term after successful canaloplasty.

Author reply: central corneal thickness determination in corneal edema

Dear Editors, We thank Nicola Rosa and Maddalena De Bernando for their crucial comments and observations. Central cornea thickness (CCT) measurement in health and disease is a difficult task, subjected to numerous patientand device-related factors. In agreement with our work, several studies have reported Pentacam CCT values to be generally higher in healthy and especially keratoconus patients [1–3]. However, as further stated in the meta-analysis by Wu [4], these differences frequently do not reach statistical significance. In addition, some authors also report the Pentacam to generate thinner CCTs than ultrasound pachymetry (USP) [5, 6]. Most of these studies were performed in healthy corneas without edema; therefore, the results are not completely interchangeable. We are currently working on a larger study addressing the question, if a significant difference in between the previously reported devices exists in different degrees of corneal edema. Because of the differences in measurements between healthy and diseased corneas, establishing a universal regression formula could be difficult. To date, we have not considered computing regression formulas in our research, but we will take this interesting approach into consideration for future projects. The application of topical anesthetic eye drops is a confounding factor in the contact USP measurements and, as a limitation of our work, no predetermined interval was adhered to between application of the eye drops and the start of USP measurements. However, we agree with Rosa and De Bernardo that it is highly unlikely that the corneal thickness decreases after application of topical anesthesia. It is likely that the thickness should increase after application of eyedrops or remain unaffected, as the authors have reported in their interesting work [7]. We believe that the comparison of the large difference between our two investigators regarding USP measurements highlights the number of confounding factors for this measuring technique (including application of topical anesthesia without a fixed Bwait time^) in particular. We feel that the user dependency, especially the correct placement on the corneal apex, which often might not completely concur with the central cornea, is a major limitation of the technique. Furthermore, we do agree with Rosa and De Bernando once again that the US measurements, in theory, should result in fake increased CCT results in cases of corneal edema. Silverman et al. reported of slower speed-of-sound in edematous bovine corneas [8]. The authors speculated that the found speed-of-sound error values and the use of a standard speed-of-sound constant would lead to an overestimation of corneal thickness determination, in corneas with 10–20% edematous swelling, of 4 to 7 μm. This error is lower than 1% of the total corneal thickness and, in our experience, variations of that amount can easily occur between repeated USP CCT measurements in healthy corneas as well. Nevertheless, we wanted to verify that the lower values in our work are not a result of a Bflawed^ study design with two measurement sessions with four single measurements each. We decided on this course of action, as we expected the highest variability in the hand-held USP measurements and wanted to minimize the influence of possible outliers as much as possible in preparation of our work. Therefore, we thank Rosa and De Bernando for the opportunity to revisit our results. To see if the cornea was compressed during the measurement sessions * D. Kuerten dkuerten@ukaachen.de