Donor lamella thickness after ultrathin Descemet stripping automated endothelial keratoplasty and its relation to postoperative visual acuity and pre-operative lamella measures.

BACKGROUND: To accurately measure ultrathin Descemet stripping automated endothelial keratoplasty (DSAEK) donor lamella thickness during the first postoperative year and to correlate this with pre-operative and other postoperative measurements. METHODS: Donor lamella thickness in 41 eyes undergoing DSAEK for Fuchs endothelial dystrophy (FED) was measured using the Tomey Casia OCT directly after graft preparation and at 1 week and 1, 3, 6 and 12 months postoperatively. Visual acuity and endothelial cell density were measured as the secondary parameters. RESULTS: Individual graft thickness profiles were shown to be fairly regular within the optically relevant area. There was a strong and highly significant correlation between the pre- and postoperative lamellar thicknesses at all time points (p < 0.0001). Compared with the measurements directly after preparation at the cornea bank, the lamella thickness decreased by 12% after 12 months. Between 1 and 12 months postoperatively, the lamella thickness (mean ± SD) changed from 112 ± 27 µm to 101 ± 21 µm. Best spectacle-corrected visual acuity (BSCVA) changed from 0.46 ± 0.30 logMAR pre-operatively through 0.36 ± 0.33 at 1 month to 0.13 ± 0.16 at 1 year postoperatively. The endothelial cell counts were comparable to those reported in previous studies. CONCLUSIONS: Thickness profiles of individual grafts were fairly regular within the optically relevant area. A strong relationship between pre- and postoperative graft thicknesses was detected, and ultrathin DSAEK grafts prepared using methods similar to that applied in this study are expected to show a deswelling of around 12% during the first postoperative year. No correlation was detected between graft thickness and BSCVA.

Deep Learning for Assessing the Corneal Endothelium from Specular Microscopy Images up to 1 Year after Ultrathin-DSAEK Surgery.

Purpose: To present a fully automatic method to estimate the corneal endothelium parameters from specular microscopy images and to use it to study a one-year follow-up after ultrathin Descemet stripping automated endothelial keratoplasty. Methods: We analyzed 383 post ultrathin Descemet stripping automated endothelial keratoplasty images from 41 eyes acquired with a Topcon SP-1P specular microscope at 1, 3, 6, and 12 months after surgery. The estimated parameters were endothelial cell density (ECD), coefficient of variation (CV), and hexagonality (HEX). Manual segmentation was performed in all images. Results: Our method provided an estimate for ECD, CV, and HEX in 98.4% of the images, whereas Topcon's software had a success rate of 71.5% for ECD/CV and 30.5% for HEX. For the images with estimates, the percentage error in our method was 2.5% for ECD, 5.7% for CV, and 5.7% for HEX, whereas Topcon's software provided an error of 7.5% for ECD, 17.5% for CV, and 18.3% for HEX. Our method was significantly better than Topcon's (P < 0.0001) and was not statistically significantly different from the manual assessments (P > 0.05). At month 12, the subjects presented an average ECD = 1377 ± 483 [cells/mm2], CV = 26.1 ± 5.7 [%], and HEX = 58.1 ± 7.1 [%]. Conclusions: The proposed method obtains reliable and accurate estimations even in challenging specular images of pathologic corneas. Translational Relevance: CV and HEX, not currently used in the clinic owing to a lack of reliability in automatic methods, are useful biomarkers to analyze the postoperative healing process. Our accurate estimations allow now for their clinical use.

The learning curve for Descemet membrane endothelial keratoplasty performed by two experienced corneal surgeons: a consecutive series of 40 cases.

PURPOSE: To describe the learning curve for Descemet's membrane endothelial keratoplasty (DMEK) in the Rotterdam Eye Hospital and to evaluate safety and visual outcome. METHODS: This was a single-centre prospective study of 40 consecutive patients with Fuchs' endothelial dystrophy who underwent a DMEK procedure in the Rotterdam Eye Hospital. The performance of two corneal surgeons, each conducting their first series of 20 procedures, was examined with the cumulative summation test for the learning curve (LC-CUSUM). The surgical procedure was considered unsuccessful when >30% of the graft was not attached at any time during the first 12 postoperative weeks and a mixture of SF6 (20%) and air (80%) had to be injected in the anterior chamber (rebubbling) to reattach the graft. Also assessed were visual outcome, intraocular pressure and peri- and postoperative complications. RESULTS: In total, nine rebubbling procedures were performed in seven eyes. Following repeated rebubbling, two eyes did not achieve a satisfactory result and secondary surgery was required to restore visual function. Complications were usually manageable. The last 13 DMEK procedures (33%) of this series did not require rebubbling. After 3 months, 86% of the eyes had reached a Snellen visual acuity of 0.5 or more. CONCLUSION: Together with the two surgeons' personal experience, the aggregate learning curve was considered to justify incorporation of Descemet membrane endothelial keratoplasty as a regular option of the standard of care for endothelial dysfunction in the Rotterdam Eye Hospital.

Corneal Endothelial Cell Segmentation by Classifier-Driven Merging of Oversegmented Images.

Corneal endothelium images obtained by in vivo specular microscopy provide important information to assess the health status of the cornea. Estimation of clinical parameters, such as cell density, polymegethism, and pleomorphism, requires accurate cell segmentation. State-of-the-art techniques to automatically segment the endothelium are error-prone when applied to images with low contrast and/or large variation in cell size. Here, we propose an automatic method to segment the endothelium. Starting with an oversegmented image comprised of superpixels obtained from a stochastic watershed segmentation, the proposed method uses intensity and shape information of the superpixels to identify and merge those that constitute a cell, using support vector machines. We evaluated the automatic segmentation on a data set of in vivo specular microscopy images (Topcon SP-1P), obtaining 95.8% correctly merged cells and 2.0% undersegmented cells. We also evaluated the parameter estimation against the results of the vendor's built-in software, obtaining a statistically significant better precision in all parameters and a similar or better accuracy. The parameter estimation was also evaluated on three other data sets from different imaging modalities (confocal microscopy, phase-contrast microscopy, and fluorescence confocal microscopy) and tissue types (ex vivo corneal endothelium and retinal pigment epithelium). In comparison with the estimates of the data sets' authors, we achieved statistically significant better accuracy and precision in all parameters except pleomorphism, where a similar accuracy and precision were obtained.

Long-Term Functional and Anatomical Outcome after Descemet Stripping Automated Endothelial Keratoplasty: A Prospective Single-Center Study.

PURPOSE: To investigate the long-term anatomical and functional outcomes of Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: Prospective follow-up of 114 eyes (95 subjects) after DSAEK for endothelial dysfunction. Measurements included best spectacle-corrected visual acuity (BSCVA), straylight, endothelial cell density (ECD), and graft thickness. RESULTS: The mean follow-up time was 5.1 ± 1.5 years. Four grafts ultimately failed (after 5 to 7 years). From baseline up to 1 year after DSAEK, mean BSCVA improved by 0.30 logMAR. This beneficial effect remained until the last follow-up (LFU). After DSAEK, straylight was reduced. ECD sharply dropped by 900 cells/mm2 (33%) immediately after surgery and, thereafter, steadily decreased at a rate of 11 cells/mm2 per month. No significant correlation was observed between graft thickness at 3 years and BSCVA. CONCLUSIONS: We observed a low graft failure rate and a normalization of graft thickness. Postoperative straylight remained elevated relative to the normal population. The sharp initial and the subsequent more gradual ECD decline are consistent with other studies. A significant and prolonged functional gain can be achieved by posterior lamellar grafting for endothelial dysfunction.

Mesencephalic dopamine neurons interfacing the shell of nucleus accumbens and the dorsolateral striatum in the rat.

Parallel corticostriatonigral circuits have been proposed that separately process motor, cognitive, and emotional-motivational information. Functional integration requires that interactions exist between neurons participating in these circuits. This makes it imperative to study the complex anatomical substrate underlying corticostriatonigral circuits. It has previously been proposed that dopaminergic neurons in the ventral mesencephalon may play a role in this circuit interaction. Therefore, we studied in rats convergence of basal ganglia circuits by depositing an anterograde neuroanatomical tracer into the ventral striatum together with a retrograde fluorescent tracer ipsilaterally in the dorsolateral striatum. In the mesencephalon, using confocal microscopy, we looked for possible appositions of anterogradely labeled fibers and retrogradely labeled neurons, "enhancing" the latter via intracellular injection of Lucifer Yellow. Tyrosine hydroxylase (TH) immunofluorescence served to identify dopaminergic neurons. In neurophysiological experiments, we combined orthodromic stimulation in the medial ventral striatum with recording from ventral mesencephalic neurons characterized by antidromic stimulation from the dorsal striatum. We observed terminal fields of anterogradely labeled fibers that overlap populations of retrogradely labeled nigrostriatal cell bodies in the substantia nigra pars compacta and lateral ventral tegmental area (VTA), with numerous close appositions between boutons of anterogradely labeled fibers and nigrostriatal, TH-immunopositive neurons. Neurophysiological stimulation in the medial ventral striatum caused inhibition of dopaminergic nigrostriatal neurons projecting to the ventrolateral striatal territory. Responding nigrostriatal neurons were located in the medial substantia nigra and adjacent VTA. Our results strongly suggest a functional link between ventromedial, emotional-motivational striatum, and the sensorimotor dorsal striatum via dopaminergic nigrostriatal neurons.

Tbx3 controls the sinoatrial node gene program and imposes pacemaker function on the atria.

The sinoatrial node initiates the heartbeat and controls the rate and rhythm of contraction, thus serving as the pacemaker of the heart. Despite the crucial role of the sinoatrial node in heart function, the mechanisms that underlie its specification and formation are not known. Tbx3, a transcriptional repressor required for development of vertebrates, is expressed in the developing conduction system. Here we show that Tbx3 expression delineates the sinoatrial node region, which runs a gene expression program that is distinct from that of the bordering atrial cells. We found lineage segregation of Tbx3-negative atrial and Tbx3-positive sinoatrial node precursor cells as soon as cardiac cells turn on the atrial gene expression program. Tbx3 deficiency resulted in expansion of expression of the atrial gene program into the sinoatrial node domain, and partial loss of sinoatrial node-specific gene expression. Ectopic expression of Tbx3 in mice revealed that Tbx3 represses the atrial phenotype and imposes the pacemaker phenotype on the atria. The mice displayed arrhythmias and developed functional ectopic pacemakers. These data identify a Tbx3-dependent pathway for the specification and formation of the sinoatrial node, and show that Tbx3 regulates the pacemaker gene expression program and phenotype.