Morphological characterization of the human corneal epithelium by in vivo confocal laser scanning microscopy

Background: Regarding the growing interest and importance of understanding the cellular changes of the cornea in diseases, a quantitative cellular characterization of the epithelium is becoming increasingly important. Towards this, the latest research offers considerable improvements in imaging of the cornea by confocal laser scanning microscopy (CLSM). This study presents a pipeline to generate normative morphological data of epithelial cell layers of healthy human corneas. Methods: 3D in vivo CLSM was performed on the eyes of volunteers (n=25) with a Heidelberg Retina Tomograph II equipped with an in-house modified version of the Rostock Cornea Module implementing two dedicated piezo actuators and a concave contact cap. Image data were acquired with nearly isotropic voxel resolution. After image registration, stacks of en-face sections were used to generate full-thickness volume data sets of the epithelium. Beyond that, an image analysis algorithm quantified en-face sections of epithelial cells regarding the depth-dependent mean of cell density, area, diameter, aggregation (Clark and Evans index of aggregation), neighbor count and polygonality. Results: Imaging and cell segmentation were successfully performed in all subjects. Thereby intermediated cells were efficiently recognized by the segmentation algorithm while efficiency for superficial and basal cells was reduced. Morphological parameters showed an increased mean cell density, decreased mean cell area and mean diameter from anterior to posterior (5,197.02 to 8,190.39 cells/mm²; 160.51 to 90.29 µm²; 15.9 to 12.3 µm respectively). Aggregation gradually increased from anterior to posterior ranging from 1.45 to 1.53. Average neighbor count increased from 5.50 to a maximum of 5.66 followed by a gradual decrease to 5.45 within the normalized depth from anterior to posterior. Polygonality gradually decreased ranging from 4.93 to 4.64 sides of cells. The neighbor count and polygonality parameters exhibited profound depth-dependent changes. Conclusions: This in vivo study demonstrates the successful implementation of a CLSM-based imaging pipeline for cellular characterization of the human corneal epithelium. The dedicated hardware in combination with an adapted image registration method to correct the remaining motion-induced image distortions followed by a dedicated algorithm to calculate characteristic quantities of different epithelial cell layers enabled the generation of normative data. Further significant effort is necessary to improve the algorithm for superficial and basal cell segmentation

What can inactivity (in its various forms) reveal about affective states in non-human animals? A review

Captive/domestic animals are often described as inactive, with the implicit or explicit implication that this high level of inactivity is a welfare problem. Conversely, not being inactive enough may also indicate or cause poor welfare. In humans, too much inactivity can certainly be associated with either negative or positive affective states. In non-human animals, however, the affective states associated with elevated or suppressed levels of inactivity are still not well understood. Part of the complexity is due to the fact that there are many different forms of inactivity, each likely associated with very different affective states. This paper has two aims. One is to identify specific forms of inactivity that can be used as indicators of specific affective states in animals. The other is to identify issues that need to be resolved before we could validly use the remaining, not yet validated forms of inactivity as indicators of affective state. We briefly discuss how inactivity is defined and assessed in the literature, and then how inactivity in its various forms relates to affective (either negative or positive) states in animals, basing our reasoning on linguistic reports of affective states collected from humans displaying inactivity phenotypically similar to that displayed by animals in similar situations, and, when possible, on pharmacological validation. Specific forms of inactivity expressed in response to perceived threats (freezing, tonic immobility, and hiding) appear to be, to date, the best-validated indicators of specific affective states in animals. We also identify a number of specific forms of inactivity likely to reflect either negative (associated with ill-heath, boredom-like, and depression-like conditions), or positive states (e.g. ‘sun-basking’, post-consummatory inactivity), although further research is warranted before we could use those forms as indicators of the affective states. We further discuss the relationship between increased inactivity and affective states by presenting misleading situations likely to yield wrong conclusions. We conclude that more attention should be paid to inactivity in animal welfare studies: specific forms of inactivity identified in this paper are, or have the potential to be, useful indicators of affective (welfare) states in animals

Dose-Response-Relationship between Number of Laser Burns and IOP Reduction in Cyclophotocoagulation: An Animal Study

Purpose. The relationship between number of laser burns of cyclophotocoagulation (CPC) and intraocular pressure (IOP) reduction is unknown. This animal model was established to reveal a possible dose-response-relationship between the number of applied laser burns and the IOP lowering effect. Methods. 30 chinchilla bastard rabbits were divided into 5 groups and treated with either 1, 5, 10, 20, or 30 CPC burns, respectively. IOP was followed up for 1 week. IOP reduction of a single 30-burn treatment was compared with a fractionated treatment (three sessions; one week in between; 10 burns/session). Results. IOP reduction increases nonlinearly with the number of CPC burns (max. -6.1±1.4 mmHg). Fractionated treatment shows similar IOP reduction with less complications and more constant results compared to single session treatment. Conclusions. The study reveals a complex relationship between IOP reduction and the number of CPC burns. Fractionated CPC gives comparable IOP reduction at a higher degree of safety

Effects of glaucoma drugs on ocular hemodynamics in normal tension glaucoma: a randomized trial comparing bimatoprost and latanoprost with dorzolamide [ISRCTN18873428]

Abstract Background Reduced choroidal perfusion is hypothesized to play a role in the pathogenesis of normal tension glaucoma. Thus the impact of antiglaucomatous eye drops on ocular perfusion has been the focus of recent research and the subject of intensive investigations. The present study investigates whether topically applied latanoprost or bimatoprost influence ocular perfusion in patients with normal tension glaucoma and compares these effects with that changes detected after the treatment with dorzolamide. Methods Ocular hemodynamics were assessed by color Doppler imaging (CDI) shortly before and after a one-month treatment with either latanoprost, bimatoprost or dorzolamide. Primary end-points of the study were peak systolic and end-diastolic blood flow velocities in the short posterior ciliary artery (SPCA) under the new therapy. Intraocular pressure (IOP) and additional perfusion parameters in the SPCA and other retrobulbar vessels were tracked as observational parameters. n = 42 patients with normal tension glaucoma were enrolled in the study. Results Systolic and diastolic blood flow velocities in the SPCA showed no significant alteration after the treatment with latanoprost or bimatoprost. Dorzolamide lead to increase of peak systolic velocity. IOP was reduced by all three agents in a range reported in the literature. Conclusion Topically applied latanoprost and bimatoprost act in a hemodynamically neutral manner and have the capability to lower IOP even in patients with normal tension glaucoma and low initial IOP level. Dorzolamide accelerates blood flow in systole. None of the tested compounds has a negative impact on hemodynamics in the short posterior ciliary arteries.</p

Effects of glaucoma drugs on ocular hemodynamics in normal tension glaucoma: a randomized trial comparing bimatoprost and latanoprost with dorzolamide ISRCTN18873428-0

<p><b>Copyright information:</b></p><p>Taken from "Effects of glaucoma drugs on ocular hemodynamics in normal tension glaucoma: a randomized trial comparing bimatoprost and latanoprost with dorzolamide [ISRCTN18873428]"</p><p>BMC Ophthalmology 2005;5():6-6.</p><p>Published online 5 Apr 2005</p><p>PMCID:PMC1087849.</p><p>Copyright © 2005 Zeitz et al; licensee BioMed Central Ltd.</p

Effects of glaucoma drugs on ocular hemodynamics in normal tension glaucoma: a randomized trial comparing bimatoprost and latanoprost with dorzolamide ISRCTN18873428-2

<p><b>Copyright information:</b></p><p>Taken from "Effects of glaucoma drugs on ocular hemodynamics in normal tension glaucoma: a randomized trial comparing bimatoprost and latanoprost with dorzolamide [ISRCTN18873428]"</p><p>BMC Ophthalmology 2005;5():6-6.</p><p>Published online 5 Apr 2005</p><p>PMCID:PMC1087849.</p><p>Copyright © 2005 Zeitz et al; licensee BioMed Central Ltd.</p