Matthias Fuest

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).

Blood Pressure and Heart Rate Variability to Detect Vascular Dysregulation in Glaucoma

Purpose. To investigate blood pressure and heart rate variability in patients with primary open-angle glaucoma (POAG) to detect disturbed blood pressure regulation. Methods. Thirty-one patients with POAG (mean age 68 ± 10 years) and 48 control subjects (mean age 66 ± 10 years) were included in a prospective study. Continuous blood pressure and heart rate were simultaneously and noninvasively recorded over 30 min (Glaucoscreen, aviant GmbH, Jena, Germany). Data were analyzed calculating univariate linear (time domain and frequency domain), nonlinear (Symbolic Dynamics, SD) and bivariate (Joint Symbolic Dynamics, JSD) indices. Results. Using nonlinear methods, glaucoma patients were separated with more parameters compared to linear methods. In POAG, nonlinear univariate indices (pW113 and pW120_Sys) were increased while the indices pTH10_Sys and pTH11_Sys reflect a reduction of dominant patterns. Bivariate indices (JSDdia29, JSDdia50, and JSDdia52; coupling between heart rate and diastolic blood pressure) were increased in POAG. The optimum set consisting of six parameters (JSDdia29, JSDdia58, pTH9_Sys, pW231, pW110_Sys and pW120_Sys) revealed a sensitivity of 83.3% and specificity of 80.6%. Conclusions. Nonlinear uni- and bivariate indices of continuous recordings of blood pressure and heart rate are altered in glaucoma. Abnormal blood pressure variability suggests disturbed autonomic regulation in patients with glaucoma.

Advances in corneal cell therapy

Corneal integrity is essential for visual function. Transplantation remains the most common treatment option for advanced corneal diseases. A global donor material shortage requires a search for alternative treatments. Different stem cell populations have been induced to express corneal cell characteristics in vitro and in animal models. Yet before their application to humans, scientific and ethical issues need to be solved. The in vitro propagation and implantation of primary corneal cells has been rapidly evolving with clinical practices of limbal epithelium transplantation and a clinical trial for endothelial cells in progress, implying cultivated ocular cells as a promising option for the future. This review reports on the latest developments in primary ocular cell and stem cell research for corneal therapy.

Monitoring intraocular pressure changes after intravitreal Ranibizumab injection using rebound tonometry

Direct drug delivery by intravitreal injection is an essential tool in the treatment of retinal diseases and can trigger transient and intermediate intraocular pressure (IOP) peaks. So far no reliable risk factors for pronounced IOP increments have been outlined, which might be particularly important for patients with increased IOP susceptibility such as glaucoma. In this prospective, interventional study IOP changes were analysed directly before and after injection in sitting and supine positions using the Icare rebound tonometer (RT).

Nerve regeneration by human corneal stromal keratocytes and stromal fibroblasts

Laser refractive surgeries reshape corneal stroma to correct refractive errors, but unavoidably affect corneal nerves. Slow nerve regeneration and atypical neurite morphology cause desensitization and neuro-epitheliopathy. Following injury, surviving corneal stromal keratocytes (CSKs) are activated to stromal fibroblasts (SFs). How these two different cell types influence nerve regeneration is elusive. Our study evaluated the neuro-regulatory effects of human SFs versus CSKs derived from the same corneal stroma using an in vitro chick dorsal root ganglion model. The neurite growth was assessed by a validated concentric circle intersection count method. Serum-free conditioned media (CM) from SFs promoted neurite growth dose-dependently, compared to that from CSKs. We detected neurotrophic and pro-inflammatory factors (interleukin-8, interleukin-15, monocyte chemoattractant protein-1, eotaxin, RANTES) in SFCM by Bio-Plex Human Cytokine assay. More than 130 proteins in SFCM and 49 in CSKCM were identified by nanoLC-MS/MS. Proteins uniquely present in SFCM had reported neuro-regulatory activities and were predicted to regulate neurogenesis, focal adhesion and wound healing. Conclusively, this was the first study showing a physiological relationship between nerve growth and the metabolically active SFs versus quiescent CSKs from the same cornea source. The dose-dependent effect on neurite growth indicated that nerve regeneration could be influenced by SF density.

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).

Tonometry in Corneal Edema after Cataract Surgery: Rebound versus Goldmann Applanation Tonometry

Abstract Purpose: Goldmann applanation tonometry (GAT) is known to be influenced by corneal properties, whereas the effect of corneal edema on intraocular pressure (IOP) measurement using Rebound tonometry (RT) is not clear. In this study, IOP was measured before and after cataract surgery using GAT and RT to investigate differences between methods and the effect of postsurgical corneal edema. Methods: Thirty patients with cataract were included in a prospective study. IOP was measured using GAT and RT (Icare PRO, Tiolat Oy, Finland) before and after one day of phacoemulsification. Central corneal thickness (CCT) was determined before and after surgery (Pentacam, Oculus, Germany). Results: CCT increased significantly after surgery by 52.2 ± 35.1 µm (p < 0.0001). IOP values of GAT and RT were significantly correlated before surgery (r = 0.65, p < 0.0001) and after surgery (r = 0.94, p < 0.0001). No significant correlation of GAT and RT to CCT before surgery (GAT: r = 0.18, p = 0.36; RT: r = 0.03, p = 0.87) or after surgery (GAT: r = −0.08, p = 0.69; RT: r = 0.17, p = 0.37) was found. The mean difference between GAT and RT (GAT-RT) was −1.0 ± 2.9 mmHg (range −6.2 to 6.4 mmHg, p = 0.08) before surgery and −1.1 ± 2.2 mmHg (range −5.1 to 4.8 mmHg, p = 0.01) after surgery. Before surgery, a positive correlation of GAT-RT with mean IOP of both methods is apparent (r = 0.45, p = 0.01). After surgery, no such correlation was found (r = −0.08, p = 0.69). Conclusions: RT underestimates IOP in higher values and overestimates IOP in lower values compared to GAT before surgery. This is not apparent in eyes with corneal edema. Large differences between methods may be present in individual patients with and without corneal edema.

Role of the Endothelial Layer in the Deswelling Process of Organ-Cultured Human Corneas Before Transplantation.

Purpose: Before corneal transplant surgery, a deswelling process of organ-cultured corneas is required. This study compares the deswelling kinetics of corneas with an intact endothelial cell layer and disrupted or removed endothelium by measuring central corneal thickness (CCT) over time using anterior segment spectral domain optical coherence tomography. Methods: Ten donor pairs were cultured in organ culture. The right and left corneas were alternately assigned to one of 2 deswelling groups. Deswelling in the first group [endothelial group (EG)] was induced using a medium with dextran 5%. Corneas of the second group [nonendothelial group (NEG)] were deprived of their endothelial cell layer by trypsinization and were then placed in the same deswelling medium. CCT (mean ± SD) was measured by anterior segment spectral domain optical coherence tomography before deswelling (0 hours) and after 1, 2, 3, 6, 12, 24, 48, 72, and 144 hours. Deswelling kinetics was analyzed through the nonlinear platform in SAS/JMP11 Pro. Results: Before deswelling, CCT was 1071.0 &mgr;m (±129.6 &mgr;m) and 1133.8 &mgr;m (±124.3 &mgr;m) in the EG and NEG, respectively. Minimum corneal thickness was obtained after 24 hours in the EG (531.9 ± 47.5 &mgr;m) and 6 hours in the NEG (645 ± 81.2 &mgr;m). CCT was significantly (P < 0.01) higher in the NEG than EG after more than 6 hours. Conclusions: Corneal dehydration after organ culture seems to be a multifactorial process, which not only depends on osmotic effects of the deswelling compound but also requires the presence of an intact endothelial cell layer.

Conjunctival and intraocular swabs for the microbiological assessment of donor corneas

In this study, we investigated the associations between conjunctival (co) and intraocular (io) swabs and their implications for the contamination rates of organ‐cultured corneas.

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.