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2018 SEP 8 (NewsRx) -- By a News Reporter-Staff News Editor at Obesity, Fitness & Wellness Week -- Investigators publish new report on Proteomics. According to news reporting originating from [...]

A study conducted at Osaka Medical and Pharmaceutical University examined the severity of eye pain in patients with aqueous-deficient dry eye (ADDE). The researchers used a pain-measuring device called PainVision(R) to assess the severity of eye pain and its correlation with objective findings. The study found that the central corneal staining score was the most significant factor affecting eye pain. Additionally, punctal occlusion treatment significantly reduced eye pain in the patients. The research suggests that central corneal epithelial damage is closely associated with ADDE-related eye pain. [Extracted from the article]

Keywords: Miami; State:Florida; United States; North and Central America; Algorithms; Antigen-Presenting Cells; Artificial Intelligence; Dendritic Cells; Emerging Technologies; Health and Medicine; Immunology; Machine Learning; Mononuclear Phagocyte System; Veterans; Veterans Health EN Miami State:Florida United States North and Central America Algorithms Antigen-Presenting Cells Artificial Intelligence Dendritic Cells Emerging Technologies Health and Medicine Immunology Machine Learning Mononuclear Phagocyte System Veterans Veterans Health 1818 1818 1 08/28/23 20230901 NES 230901 2023 SEP 1 (NewsRx) -- By a News Reporter-Staff News Editor at Health & Medicine Week -- Data detailed on Veterans have been presented. Keywords for this news article include: Miami, Florida, United States, North and Central America, Algorithms, Antigen-Presenting Cells, Artificial Intelligence, Dendritic Cells, Emerging Technologies, Health and Medicine, Immunology, Machine Learning, Mononuclear Phagocyte System, Veterans, Veterans Health, University of Miami. [Extracted from the article]

To compare small nerve fiber damage in the central cornea and whorl area in participants with diabetic peripheral neuropathy (DPN) and to examine the accuracy of evaluating these 2 anatomical sites for the diagnosis of DPN.

Reviewed by Nathan Congdon, MD MPH Fort Lauderdale, FL--Both a thin central cornea and low corneal hysteresis are independently associated with increased risk for glaucoma damage. The jury is still [...]

Reviewed by Eve J. Higginbotham, MD Editor's note: This is the second story in a three-part series covering a forum on 'Ethnicity and Glaucoma' at Johns Hopkins University to commemorate [...]

To validate an algorithm quantifying activated dendritic cells (aDCs) using in-vivo confocal microscopy (IVCM) images.

Infection on the snout with HSV-1 in mice with normal corneas produced a mild ocular disease, characterized by a zosteriform skin lesion around the eye, enlargement of the pupil, hyperemia of the iris and, sporadically, transient keratitis. By contrast, snout infection after prior cauterization of the cornea induced significantly more frequent and more severe corneal disease, in which keratitis was usually permanent. Corneal cauterization also produced increased numbers of Langerhans cells in the central cornea. We speculate that the combination of virus and increased numbers of Langerhans cells within the cornea may lead to an exaggerated ocular immune response that is destructive to the cornea.

B Author Information b An event is serious (based on the ICH definition) when the patient outcome is: * death * life-threatening * hospitalisation * disability * congenital anomaly * other medically important event A male patient [ I age not stated i ] exhibited reversible visual loss secondary to deposits of ciprofloxacin in the central cornea during treatment with ciprofloxacin eye drops. Therefore, the patient discontinued the application of ciprofloxacin eye drops and received preservative-free tear substitute in an hourly manner. [Extracted from the article]

A recent study conducted at Chang Gung Memorial Hospital in Linkou, Taiwan, compared the impact of femtosecond laser-assisted cataract surgery (FLACS) and conventional phacoemulsification surgery (CPS) on corneal endothelial cells in different regions. The research found that FLACS patients experienced less endothelial cell loss (ECL) at 3 and 6 months postoperatively, particularly in the central cornea. However, ongoing ECL near the main wound at 6 months suggested continued endothelial remodeling in that region. This peer-reviewed study provides valuable insights into the effects of different surgical techniques on corneal endothelial cells. [Extracted from the article]

University of Granada researchers have conducted a study on tissue engineering, specifically focusing on the development of human artificial corneas (HAC) using nanostructured fibrin-agarose biomaterials. The research compared the structure and composition of HAC with native corneas and limbus, finding that HAC may be more biomimetic to the corneal limbus than the central cornea. This study suggests that HAC could potentially be used in patients with limbal deficiency. For more information, readers can refer to the original article published in BMC Medicine. [Extracted from the article]

A recent preprint abstract discusses the role of the Sox9 gene in regulating the asymmetric fates of limbal stem cells and their progeny in the corneal epithelium. The study utilized an in vivo cell cycle reporter and single-cell transcriptional analysis to identify distinct basal cell identities with unique expression profiles. Sox9 was found to be differentially expressed between limbal stem cells and their progeny, and its conditional deletion led to abnormal differentiation and squamous metaplasia in the central cornea. The findings suggest that Sox9 plays an essential role in the spatial regulation of asymmetric fate in the corneal epithelium, which is necessary for tissue homeostasis. [Extracted from the article]

The patient interface of claim 8, wherein: the contact element is configured for insertion into the contact portion; and the contact portion is configured to accept the insertion of the contact element. The patient interface of claim 8, wherein: the attachment portion is separate from the contact portion; and the attachment portion is configured to be coupled to the contact portion after the contact portion has been docked to the eye. The patient interface of claim 8, the contact portion comprising: an escape structure, configured to assist an expulsion of air from a contact space between the transparent central portion and the central-cornea. [Extracted from the article]

The cornea needs to be transparent to visible light and precisely curved to provide the correct refractive power. Both properties are governed by its structure. Corneal transparency arises from constructive interference of visible light due to the relatively ordered arrangement of collagen fibrils in the corneal stroma. The arrangement is controlled by the negatively charged proteoglycans surrounding the fibrils. Small changes in fibril organisation can be tolerated but larger changes cause light scattering. Corneal keratocytes do not scatter light because their refractive index matches that of the surrounding matrix. When activated, however, they become fibroblasts that have a lower refractive index. Modelling shows that this change in refractive index significantly increases light scatter. At the microscopic level, the corneal stroma has a lamellar structure, the parallel collagen fibrils within each lamella making a large angle with those of adjacent lamellae. X-ray scattering has shown that the lamellae have preferred orientations in the human cornea: inferior-superior and nasal-temporal in the central cornea and circumferential at the limbus. The directions at the centre of the cornea may help withstand the pull of the extraocular muscles whereas the pseudo-circular arrangement at the limbus supports the change in curvature between the cornea and sclera. Elastic fibres are also present; in the limbus they contain fibrillin microfibrils surrounding an elastin core, whereas at the centre of the cornea, they exist as thin bundles of fibrillin-rich microfibrils. We present a model based on the structure described above that may explain how the cornea withstands repeated pressure changes due to the ocular pulse.

The patient interface of claim 1, the contact portion comprising: an escape structure, configured to assist an expulsion of air from a contact space between the transparent central portion and the central-cornea. The patient interface of claim 1, wherein: the contact element is configured for insertion into the contact portion; and the contact portion is configured to accept the insertion of the contact element. The patient interface of claim 1, wherein: the attachment portion is separate from the contact portion; and the attachment portion is configured to be coupled to the contact portion after the contact portion has been docked to the eye. [Extracted from the article]

A patent has been issued for a bi-radial patient interface by Alcon Inc. The patent describes a patient interface that attaches an ophthalmic system to the eye for anterior segment eye procedures, such as cataract procedures. The patient interface aims to reduce corneal wrinkling, which can hinder the precision of ophthalmic surgical procedures. The interface includes a contact element with a central portion and a peripheral portion, where the central radius of curvature is smaller than the peripheral radius of curvature. The patent provides detailed claims and specifications for the patient interface. [Extracted from the article]

Severe dry eye (SDE) can cause grievous damage to the ocular surface and result in vision impairment and even blindness. To investigate the fate of limbal stem cells in SDE and the underlying mechanism, the current study established an SDE rat model by removing the extraorbital and infraorbital lacrimal glands and maintaining them in a low-humidity environment. One month after the surgery, aqueous tear secretion was reduced dramatically, blood vessels invaded into the central cornea, and inflammatory cells infiltrated into the limbal stroma. The expressions of keratin 12 and paired box gene 6 were down-regulated dramatically, while those of keratin 10, small proline-rich protein 1b, and mucin 5AC were up-regulated in the corneal epithelium of the SDE rats. Cell proliferation in the limbal epithelium was up-regulated, while the stem/progenitor marker adenosine 5′-triphosphate-binding cassette member 2 and the limbal epithelial colony-forming efficiency were decreased in the SDE condition. Furthermore, the p38 mitogen-activated protein kinase signaling pathway was activated in the limbal corneal epithelium of SDE rats. The abnormal differentiation and stemness loss in the corneal epithelium could be reversed upon treatment with a p38 inhibitor in a SDE in vivomodel and in vitrohyperosmolar corneal epithelial culture conditions. These data suggest that SDE can lead to limbal stem cell dysfunction, and p38 mitogen-activated protein kinase signaling pathway activation plays an essential role in this process.

A clinical trial, NCT06397976, has been launched to compare the investigational device ANTERION with software version 1.5 against the ANTERION with software version 1.2.4. The trial aims to assess the reproducibility and repeatability of various measurements, such as central cornea thickness, thinnest point thickness, lens thickness, anterior chamber depth, and axial length. The study includes eyes with both normal and abnormal anterior segments, and the estimated enrollment is 60 participants. The trial is currently recruiting and is expected to be completed by December 30, 2025. [Extracted from the article]

Purpose To report the case of persistent corneal epithelial defect in total limbal stem cell deficiency (LSCD) after severe firework-related ocular burn treated with autologous Platelet-Rich Plasma (PRP).Case description A young patient, victim of fireworks trauma, presented with a large persistent epithelial defect affecting the central cornea of his left eye and progressing to stromal melting, in the context of grade VI ocular surface burn with 12 h limbal involvement. Impression cytology to the cornea confirmed a complete LSCD. Assessment of corneal sensitivity by Cochet Bonnet esthesiometer revealed complete corneal anesthesia. Based on progressive clinical worsening under conventional therapy, the patient was started on very pure autologous PRP eye drops obtained using the Hy-Tissue PRP® technology. Six times a day eye drops administration for 30 days was scheduled in the affected eye. At the end of treatment, the epithelial defect had disappeared being replaced by advancing conjunctiva.Conclusion Our findings provide information on management of ocular burns from fireworks, a subject of current interest and concern. Autologous PRP eye drops prepared using the Hy-Tissue PRP® system and administered in the presence of total LSCD and complete corneal anesthesia, prevented corneal stromal melting to progress and allowed the ocular surface epithelial coverage to re-establish. This paved the way for later successful restorative and reconstructive intervention. Also, first description of the Hy-tissue PRP procedure for ophthalmological use is reported.

Introduction This study investigated the morphological characteristics of corneal microstructure in the quiescent phase of vernal keratoconjunctivitis (VKC).Methods Twenty patients with quiescent VKC and 25 healthy subjects were included. In vivo confocal microscopy (IVCM) of the central cornea was performed. Cellular density of each layer and the morphology of subbasal nerve plexus (SBNP) was analysed. Langerhans cell density (LCD), morphology (LCM), and field area (LCF) were also examined.Results No differences were found either in cell densities nor in SBNP morphology (p> 0.05). LCD, LCM and LCF were significantly higher in the VKC group (p= 0.005, p< 0.001 and p< 0.001, respectively). The severity of papillary hypertrophy had a significant impact on LCD, LCM and LCF (β-coefficient: 19.541, p< 0.001; β-coefficient: 0.283, p< 0.001 and β-coefficient: 595.255, p< 0.001, respectively).Discussion In quiescent VKC, LCD, LCM, and LCF were increased, and they were associated with the severity of papillary hypertrophy. Alterations of Langerhans cells indicate a subclinical inflammatory process without ocular symptoms.

A recent study conducted at the Eye and ENT Hospital of Fudan University compared the measurements of corneal and lens densities obtained by two different devices, Pentacam and CASIA2, in myopic patients. The study found that CASIA2 showed higher density values compared to Pentacam in all measured zones. However, despite the numerical differences, CASIA2 was deemed a reliable alternative method for densitometric measurements. The study concluded that CASIA2 demonstrated good consistency with Pentacam, except for measurements in the central cornea and in cases of high myopia. [Extracted from the article]

The outermost layer of the eye, the cornea, is renewed continuously throughout life. Stem cells of the corneal epithelium reside in the limbus at the corneal periphery and ensure homeostasis of the central epithelium. However, in young mice, homeostasis relies on cells located in the basal layer of the central corneal epithelium. Here, we first studied corneal growth during the transition from newborn to adult and assessed Keratin 19 (Krt19) expression as a hallmark of corneal maturation. Next, we set out to identify a novel marker of murine corneal epithelial progenitor cells before, during and after maturation, and we found that Bmi1is expressed in the basal epithelium of the central cornea and limbus. Furthermore, we demonstrated that Bmi1+cells participated in tissue replenishment in the central cornea. These Bmi1+cells did not maintain homeostasis of the cornea for more than 3 months, reflecting their status as progenitor rather than stem cells. Finally, after injury, Bmi1+cells fueled homeostatic maintenance, whereas wound closure occurred via epithelial reorganization. StemCells2018;36:562–573 Corneal renewal is a dynamic process. Basally located central epithelial progenitor cells maintain the corneal layers for a limited time, whereas stem cells reside in the limbus. Healing after injury occurs via reorganization of the epithelium.

MiR-146a upregulated in limbus vs. central cornea and in diabetic vs. non-diabetic limbus has emerged as an important immune and inflammatory signaling mediator in corneal epithelial wound healing. Our aim was to investigate the potential inflammation-related miR-146a target genes and their roles in normal and impaired diabetic corneal epithelial wound healing.

AimsTo evaluate the impact of herpes simplex virus (HSV)-induced scar location on bilateral corneal nerve alterations using laser in vivo confocal microscopy (IVCM).MethodsCentral and peripheral corneal subbasal nerve density (CSND) were assessed bilaterally in 39 patients with unilateral HSV-induced corneal scars (21 central scars (CS), 18 peripheral scars (PS)) using IVCM. Results were compared between patients and 24 age-matched controls. CSND was correlated to corneal sensation for all locations.ResultsOverall patients revealed significant decrease of CSND in the central and peripheral cornea (9.13±0.98 and 6.26±0.53 mm/mm2, p<0.001), compared with controls (22.60±0.77 and 9.88±0.49 mm/mm2). CS group showed a decrease in central (8.09±1.30 mm/mm2) and total peripheral nerves (5.15±0.62 mm/mm2) of the affected eyes, whereas PS group demonstrated a decrease in central (10.34±1.48 mm/mm2) and localised peripheral nerves only in the scar area (4.22±0.77 mm/mm2) (all p<0.001). In contralateral eyes, CSND decreased in the central cornea of the CS group (16.88±1.27, p=0.004), and in the peripheral area, mirroring the scar area in the affected eyes of the PS group (7.20±0.87, p=0.032). Corneal sensation significantly decreased in the whole cornea of the affected, but not in contralateral eyes (p<0.001). A positive correlation between CSND and corneal sensation was found in all locations (p<0.001).ConclusionsPatients with HSV scar demonstrate bilateral CSND decrease as shown by IVCM. CSND and corneal sensation decrease in both central and peripheral cornea in affected eyes, although only in the scar area in PS group. Interestingly, diminishment of CSND was found locally in the contralateral eyes, corresponding and mirroring the scar location in the affected eyes.

Purpose: To investigate the role of oxidative stress in keratocytes in the pathogenesis of keratoconus (KC) using the rabbit cornea as a model.Methods: Immerse the rabbit cornea in collagenase type II solution at room temperature for 30 min in the KC group. The central cornea thickness (CCT), and mean keratometry (Km) were examined before and after the procedure. Reactive oxygen species (ROS), the nuclear translocation of nuclear factor E2-related factor 2 (NRF-2), the expression of heme oxygenase-1 (HO-1) protein, and nicotinamide adenine dinucleotide phosphate (NADPH) Oxidase (NOX) family members NOX-2 and NOX-4 protein levels were examined by immunohistochemistry analysis and Western Blot. The expression levels of HO-1, NOX-2, NOX-4, and NRF-2 mRNA were quantitatively detected by Real-time PCR.Results: A significant increase in Km and a significant decrease in CCT were observed in the KC group compared with the control group after the surgery (both p< 0.001). Immunofluorescence staining showed the rabbit KC model induced a significant increase in ROS production (p< 0.001). The expression of HO-1, NOX-2, NOX-4, and NRF-2 proteins in the KC group were significantly higher than those in the control group (all p< 0.001). RT-PCR results showed the levels of HO-1, NOX-2, NOX-4, and NRF-2 mRNA in KC groups were all significantly increased compared with control groups (all p< 0.05).Conclusions: Oxidative stress and compensatory activation of antioxidant proteins suggest oxidative stress injury in corneal stromal cells plays an important role in the development of KC in a rabbit model.

PurposeAnalysis of microstructural alterations of corneal and limbal epithelial cells in healthy human corneas and in other ocular conditions.Patients and methodsUnilateral eyes of three groups of subjects include healthy volunteers (G1, n=5), contact lens wearers (G2, n=5), and patients with dry eyes (G3, n=5) were studied. Imaging of basal (BC) and intermediate (IC) epithelial cells from central cornea (CC), corneal limbus (CL) and scleral limbus (SL) was obtained by in vivo confocal microscopy (IVCM). An appropriate image analysis algorithm was used to quantify morphometric parameters including mean cell area, compactness, solidity, major and minor diameter, and maximum boundary distance.ResultsThe morphometric parameters of BC and IC demonstrated no significant differences (P>0.05) between groups. Comparison between three corneal locations (CC, CL, and SL) within the groups showed significant differences (P<0.05) with mean values of cell area, compactness, solidity, and major and minor diameter of BC that increase from CC to limbus. The BC were round and regular in the central cornea (P<0.05) compared with CL and SL.ConclusionsIVCM enables high-quality confocal images from central corneal and limbal epithelium. This quantitative study demonstrated morphological differences in the basal and intermediate epithelium between limbus and central cornea, and found no differences between contact lens wearers, dry eyes, and normal subjects.

Purpose To compare the short-term changes in corneal endothelial cells after trabeculectomy or XEN Gel Stent implantation.Design Prospective, interventional, comparative study.Methods Changes in corneal endothelium in patients that underwent XEN Gel Stent implantation or trabeculectomy were prospectively evaluated. Eighty eyes of 62 diagnosed with open-angle glaucoma were divided into two the trabeculectomy and XEN Gel Stent groups. Corneal specular microscopy was performed at the central cornea using a noncontact specular microscope preoperatively and 3 months after surgery.Results The baseline mean corneal endothelial cell density in the trabeculectomy group was 2390.3 ± 324.8 cells/mm2, and this was significantly reduced to 2148 ± 352.5 cells/mm23 months after surgery, representing a cell loss of 10.0% (p < 0.001). The baseline mean corneal endothelial cell density in the XEN Gel Stent group was 2156.2 ±559.7 cells/mm2, and this was significantly reduced to 2098.4 ± 556.2 cells/mm23 months after surgery, representing a cell loss of 2.1% (p = 0.002). The corneal endothelial cell density change rate of the trabeculectomy group (−10.0% ± 9.7%) was statistically higher than the XEN Gel Stent group (−2.1% ± 13.8%) (p = 0.002). A statistically significant difference was observed in the trabeculectomy group between the baseline and postoperative values in the coefficient of variation (p = 0.029).Conclusion Trabeculectomy caused more endothelial cell damage than XEN Gel Stent implantation in the short-term follow-up period. The XEN Gel Stent may be the treatment of choice in patients with a significantly low preoperative corneal endothelial cell density.

Stem cell (SC) division, deployment, and differentiation are processes that contribute to corneal epithelial renewal. Until now studying the destiny of these cells in a living mammal has not been possible. However, the advent of inducible multicolor genetic tagging and powerful imaging technologies has rendered this achievable in the translucent and readily accessible murine cornea. K14CreERT2‐Confetti mice that harbor two copies of the Brainbow 2.1 cassette, yielding up to 10 colors from the stochastic recombination of fluorescent proteins, were used to monitor K‐14+progenitor cell dynamics within the corneal epithelium in live animals. Multicolored columns of cells emerged from the basal limbal epithelium as they expanded and migrated linearly at a rate of 10.8 µm/day toward the central cornea. Moreover, the permanent expression of fluorophores, passed on from progenitor to progeny, assisted in discriminating individual clones as spectrally distinct streaks containing more than 1,000 cells within the illuminated area. The centripetal clonal expansion is suggestive that a single progenitor cell is responsible for maintaining a narrow corridor of corneal epithelial cells. Our data are in agreement with the limbus as the repository for SC as opposed to SC being distributed throughout the central cornea. This is the first report describing stem/progenitor cell fate determination in the murine cornea using multicolor genetic tracing. This model represents a powerful new resource to monitor SC kinetics and fate choice under homeostatic conditions, and may assist in assessing clonal evolution during corneal development, aging, wound‐healing, disease, and following transplantation. StemCells2015;33:157–169

This case series examines the magnitude and regional variation in scleral lens–induced corneal edema in postradial keratotomy (RK) eyes. Scheimpflug imaging was used to measure corneal thickness across the central 6 mm before and after scleral lens wear in nine post-RK eyes (median age 64 years). Variations in corneal edema were examined as a function of distance from the corneal center (six 0.5-mm annuli) and from 0° to 360°. The median central corneal edema was 2.19% (interquartile range 1.03%–3.18%; P=0.02) and increased in magnitude and variability further from the central cornea (from 1.30% in the central 0–0.5 mm to 3.12% in the 2.5–3.0 mm midperiphery) (P=0.02). Scleral lens–induced corneal edema in post-RK eyes was greater in magnitude further from the corneal center and at the approximate location of corneal incisions.

PURPOSE:To compare anterior chamber depth (ACD) and aqueous depth (AQD) measurements provided by a Scheimpflug camera combined with corneal topography to those obtained by immersion ultrasound (US) biometry when assessing the distance between the cornea and intraocular lens (IOL) in pseudophakic patients.METHODS:In a sample of 40 consecutive patients, each patient underwent measurements of ACD and AQD by means of the two techniques. Scheimpflug (Sirius; C.S.O., Firenze, Italy) measurements were obtained by manually tracing a line between the anterior surface of the IOL and the central cornea. Results were compared by In a sample of 40 consecutive patients, each patient underwent measurements of ACD and AQD by means of the two techniques. Scheimpflug (Sirius; C.S.O., Firenze, Italy) measurements were obtained by manually tracing a line between the anterior surface of the IOL and the central cornea. Results were compared by ttest. Agreement was evaluated by Bland–Altman plots with 95% limits of agreement (LoA).RESULTS:There was no statistically significant difference between the AQD as measured by US (3.95 ± 0.34 mm; range: 3.39 to 4.74 mm) and the AQD as measured by Scheimpflug photography (3.96 ± 0.34 mm; range: 3.41 to 4.77 mm; There was no statistically significant difference between the AQD as measured by US (3.95 ± 0.34 mm; range: 3.39 to 4.74 mm) and the AQD as measured by Scheimpflug photography (3.96 ± 0.34 mm; range: 3.41 to 4.77 mm; P= .3187). The statistically (but not clinically) significant difference between the ACD as measured by US (4.54 ± 0.37 mm; range: 3.93 to 5.35 mm) and Scheimpflug photography (4.58 ± 0.34 mm; range: 4.03 to 5.36 mm; P= .0024) disappeared after setting the US speed for ACD at 1,545 m/sec (mean ACD: 4.58 ± 0.37 mm; range: 3.96 to 5.39 mm). The 95% LoA ranged between −0.15 and +0.18 mm for AQD and between −0.12 and +0.21 mm for ACD.CONCLUSIONS:In pseudophakic eyes, the manual ACD and AQD measurements obtained from the Scheimpflug camera combined with corneal topography are not significantly different compared to those provided by US and therefore can be considered interchangeable with the latter.

PURPOSE:To compare the corneal collagen cross-linking (CXL) demarcation line depth between the central and peripheral cornea after cross-linking using anterior segment optical coherence tomography.METHODS:Retrospective interventional case series of 38 eyes with keratoconus or postoperative LASIK ectasia treated with riboflavin ultraviolet A CXL (UV-X, IROC). CXL demarcation line depth, corneal thickness, and the ratio of the CXL demarcation line depth to the corneal thickness were measured using anterior segment optical coherence tomography at the central cornea and at 2 and 4 mm from the corneal center in four regions: temporal, nasal, superior, and inferior. The CXL demarcation line depths at the center and periphery were compared using the Friedman test.RESULTS:The CXL demarcation line was deepest in the central cornea (302 μm; range: 180 to 397 μm) and was reduced progressively toward the peripheral cornea, at nasal 2 mm (289.5 μm; range: 125 to 370 μm), at nasal 4 mm (206.5 μm; range: 100 to 307 μm), at temporal 2 mm (278.5 μm; range: 128 to 375 μm), and at temporal 4 mm (194 μm; range: 80 to 325 μm) (The CXL demarcation line was deepest in the central cornea (302 μm; range: 180 to 397 μm) and was reduced progressively toward the peripheral cornea, at nasal 2 mm (289.5 μm; range: 125 to 370 μm), at nasal 4 mm (206.5 μm; range: 100 to 307 μm), at temporal 2 mm (278.5 μm; range: 128 to 375 μm), and at temporal 4 mm (194 μm; range: 80 to 325 μm) (P<.001). The penetration proportion was greatest at the central cornea (64.8%; range: 44% to 80%) and was decreased toward the periphery, at nasal 2 mm (53.8%; range: 30% to 74%), at nasal 4 mm (33.8%; range: 19% to 53%), at temporal 2 mm (54.1%; range: 29% to 77%), and at temporal 4 mm (34.1%; range: 15% to 54%) (P⩽.001).CONCLUSIONS:Both the CXL demarcation line depth and its proportion over the corneal thickness were greater at the central cornea than the peripheral cornea.

AimTo investigate changes in corneal endothelial cell density (CECD) after trabeculectomy.MethodsThis prospective, observational study followed 117 eyes of 117 patients for 2 years after trabeculectomy. The central cornea was examined by corneal specular microscopy prior to and at every 6 months after the surgery. Survival analysis of patients who exhibited a 10% or less reduction of the postoperative CECD compared with preoperative levels was assessed using the Kaplan-Meier survival curve. A Cox proportional hazards model was used to evaluate prognostic factors for decreasing CECD.ResultsAt baseline, the mean CECD was 2420±357 cells/mm2, while at 6, 12, 18 and 24 months after surgery, the mean CECD was 2324±373 cells/mm2(p<0.001), 2276±400 cells/mm2(p<0.001), 2290±398 cells/mm2(p<0.001) and 2267±446 cells/mm2(p<0.001), respectively. At 6, 12, 18 and 24 months after surgery, the results of the Kaplan-Meier survival analysis of the 10% loss of CECD from baseline were 91%, 85%, 83% and 77%, respectively. Uveitic glaucoma was a significant prognostic factor for decreasing CECD (p=0.041).ConclusionsCECD significantly and continuously decreased after trabeculectomy.

PURPOSE:To describe clinical characteristics, risk factors, and visual outcomes in patients requiring flap lift for epithelial ingrowth following LASIK.METHODS:Consecutive, noncomparative, retrospective case series of eyes requiring flap lift for epithelial ingrowth following LASIK from June 2003 through July 2011 at a tertiary care, university-based eye hospital. Main outcome measures were uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) at 1 and 3 months and recurrence of epithelial ingrowth.RESULTS:Forty-five eyes were included. Laser in situ keratomileusis retreatment was the most common etiologic factor for epithelial ingrowth (28/45 eyes [62%]). All patients were treated with flap lift and scraping. Mean logMAR UDVA at presentation was 0.28 (Snellen equivalent 20/38). Mean logMAR UDVA at 3 months was 0.17 (Snellen equivalent 20/30) with 53% of eyes 20/25 or better. Mean logMAR CDVA at 3 months was 0.06 (Snellen equivalent 20/23) with 78% of eyes 20/25 or better. Epithelial ingrowth into the central cornea portended a trend towards UDVA worse than 20/25 or worse at 3-month follow-up (hazard ratio [HR] 5.54, 95% confidence interval [CI]: 0.98–31.3, Forty-five eyes were included. Laser in situ keratomileusis retreatment was the most common etiologic factor for epithelial ingrowth (28/45 eyes [62%]). All patients were treated with flap lift and scraping. Mean logMAR UDVA at presentation was 0.28 (Snellen equivalent 20/38). Mean logMAR UDVA at 3 months was 0.17 (Snellen equivalent 20/30) with 53% of eyes 20/25 or better. Mean logMAR CDVA at 3 months was 0.06 (Snellen equivalent 20/23) with 78% of eyes 20/25 or better. Epithelial ingrowth into the central cornea portended a trend towards UDVA worse than 20/25 or worse at 3-month follow-up (hazard ratio [HR] 5.54, 95% confidence interval [CI]: 0.98–31.3, P=.05) and CDVA worse than 20/25 at 3-month follow-up (HR 4.32, 95% CI: 0.85–21.9, P=.08). Recurrence after treatment was 31% at 3 months and 36% at 1 year. Risk factors for recurrence included: infectious etiology of ingrowth (HR 5.7, 95% CI: 1.11–29.1, P=.04), use of microkeratome for primary LASIK (HR 4.64, 95% CI: 1.07–20.1, P=.04), and hyperopic primary LASIK (HR 2.49, 95% CI: 0.98–6.31, P=.06).CONCLUSIONS:Patients undergoing flap lift for the treatment of epithelial ingrowth have a relatively high rate of recurrence but good visual acuity outcomes.

OBJECTIVE To evaluate the cellular changes in the corneal epithelium and surrounding structures in limbal stem cell deficiency (LSCD) by using in vivo laser scanning confocal microscopy. METHODS This was a prospective comparative study that included 27 eyes of 20 patients with LSCD and 12 eyes of 10 healthy subjects. All subjects underwent slitlamp examination, and LSCD was classified into 3 groups on the basis of clinical presentation. Confocal imaging of the central cornea and 4 locations of limbus was performed. Morphologic characteristics of the corneal epithelium were studied. The basal epithelial cell density and subbasal nerve density in the central cornea were calculated, and a potential correlation between the decrease in basal epithelial cell density and subbasal nerve density in LSCD was investigated. RESULTS The wing and basal epithelial cells became progressively metaplastic, and the basal epithelial cell density and subbasal nerve density in the early and intermittent stages decreased significantly compared with controls (all P &lt; .01). Normal basal epithelial cell morphology was completely lost and subbasal nerves were absent in the late stage of LSCD. The decrease in basal cell density correlated with the decrease in subbasal nerve density in patients with LSCD (P = .03). CONCLUSIONS There are significant microstructural changes associated with early LSCD. These cellular changes could help to understand the disease process and classify and monitor limbal stem cell dysfunction.

This article investigates in vitro light transmission through the human cornea in the ultraviolet (UV) portion of the electromagnetic spectrum as a function of position across the cornea from center to periphery. Spectrophotometry was used to measure UV transmission in the wavelength range 310–400 nm, from the central cornea to its periphery. UV transmission decreases away from the center, and this is attributed to scattering and absorbance. Corneal endothelial cells, which line the back of the cornea and are more numerous in the periphery, therefore receive a lower dose of UV than do those in the central cornea. This is consistent with the recent observation that endothelial cells in the corneal periphery exhibit less nuclear oxidative DNA damage than those in the central cornea.

A 19-year-old Nepalese male presented with complaints of bilateral ocular discomfort, photophobia, watering, and redness for 1 week. Visual acuity was 6/12 and 6/60 in the right and left eye, respectively. On biomicroscopic examination, presence of peripheral stromal infiltrates with conjunctival follicles was noted; infiltrates progressed to involve central cornea with further decrease in vision over next few days. After ruling out infectious keratitis, detailed systemic examination and laboratory investigations were diagnostic of neuro-Behçet’s disease. Patient responded to systemic steroidal and immunosuppressive therapy characterized by corneal healing and visual acuity improvement to 6/6 and 6/9. Although rare, but neuro-Behçet’s disease can primarily present as bilateral immune keratitis and every case of bilateral keratitis needs early systemic evaluation after ruling out infective etiologies.

We evaluated the dynamics of ocular surface temperature using thermal imaging in 21 glaucoma subjects and 19 healthy subjects. On opening of the eye, subjects with glaucoma showed significantly cooler temperatures in the central cornea compared to the control group. The upper eyelid was also significantly cooler just before the eye opened. Immediately after opening the eye, the dynamic of temperature change was different in the two groups. In subjects with glaucoma, the eyes cooled significantly faster, with an average decrease of 0.49°C during the first second compared to 0.24°C in the control group. Our results support the hypothesis that both the stability of the tear film and changes in the ocular blood supply in subjects with glaucoma play an important role in thermal dynamics of the ocular surface.

OBJECTIVE To evaluate the differences in aqueous humor dynamics between nighttime and daytime in participants with ocular hypertension. METHODS Thirty participants (mean [SD] age, 59.2 [11.1] years) with ocular hypertension were enrolled in the study, which included 1 daytime and 1 nighttime visit. During each visit, measurements included central cornea thickness by ultrasound pachymetry, intraocular pressure (IOP) by pneumatonometry, aqueous flow by fluorophotometry, outflow facility by tonography, and blood pressure by sphygmomanometry. Uveoscleral outflow was calculated using the Goldmann equation. Daytime measurements were made only of episcleral venous pressure by venomanometry, anterior chamber depth by A-scan, and outflow facility by fluorophotometry. Repeated-measures analysis of variance and 2-tailed t tests were used for statistical comparisons. RESULTS Compared with daytime seated IOP (21.3 [3.5] mm Hg), nighttime seated IOP (17.2 [3.7] mm Hg) was reduced (P &lt; .001) and nighttime supine IOP (22.7 [4.6] mm Hg) was increased (P = .03). Central cornea thickness was increased at night from 570 (39) μm to 585 (46) μm (P &lt; .001). There was a 48% nocturnal reduction in aqueous flow from 2.13 (0.71) μL/min during the day to 1.11 (0.38) μL/min at night (P &lt; .001). Uveoscleral outflow was significantly reduced (P = .03) by 0.61μL/min at night when using supine IOP, tonographic outflow facility, and episcleral venous pressure adjusted for postural changes in the Goldmann equation. All other measurements had no significant changes. CONCLUSIONS Significant ocular changes occur at night in individuals with ocular hypertension, including a reduction in seated IOP but an increase in habitual IOP, thickening of the cornea, and decreases in aqueous flow and uveoscleral outflow. Outflow facility does not change significantly at nighttime.

The collagen microstructure of the peripheral cornea is important in stabilizing corneal curvature and refractive status. However, the manner in which the predominantly orthogonal collagen fibrils of the central cornea integrate with the circumferential limbal collagen is unknown. We used microfocus wide-angle x-ray scattering to quantify the relative proportion and orientation of collagen fibrils over the human corneolimbal interface at intervals of 50 μm. Orthogonal fibrils changed direction 1–1.5 mm before the limbus to integrate with the circumferential limbal fibrils. Outside the central 6 mm, additional preferentially aligned collagen was found to reinforce the cornea and limbus. The manner of integration and degree of reinforcement varied significantly depending on the direction along which the limbus was approached. We also employed small-angle x-ray scattering to measure the average collagen fibril diameter from central cornea to limbus at 0.5 mm intervals. Fibril diameter was constant across the central 6 mm. More peripherally, fibril diameter increased, indicative of a merging of corneal and scleral collagen. The point of increase varied with direction, consistent with a scheme in which the oblique corneal periphery is reinforced by chords of scleral collagen. The results have implications for the cornea's biomechanical response to ocular surgeries involving peripheral incision.

OBJECTIVES To investigate the daytime vs nighttime differences in intraocular pressure (IOP), aqueous humor dynamics, central cornea thickness, and blood pressure among a cohort of healthy volunteers. METHODS Thirty healthy volunteers (mean [SD] age, 57.0 [8.6] years) were enrolled in the study. Individuals underwent 1 daytime visit and 1 nighttime visit for the measurement of aqueous humor dynamics. Measurements included IOP by pneumatonometry, aqueous flow by fluorophotometry, outflow facility by fluorophotometry and tonography, uveoscleral outflow by mathematical calculation, central cornea thickness by pachymetry, and blood pressure by sphygmomanometry. Results between visits were compared by appropriate t test. Dependence of the pneumatonometer probe results on position was tested in enucleated rabbit eyes at set pressures and probe positions. RESULTS Compared with daytime seated IOP, nighttime seated IOP was reduced by 16%, whereas nighttime supine IOP was increased by 17% (P &lt; .001 for both). The IOP changes were independent of the pneumatonometer probe position. Central cornea thickness was increased at nighttime from a mean (SD) of 560 (37) μm to a mean (SD) of 574 (37) μm (P &lt; .001). Compared with daytime aqueous flow, nighttime aqueous flow was reduced by 49% (P &lt; .001). During the night, fluorophotometric outflow facility was reduced by 45% (P = .05), and tonographic outflow facility was reduced by 17% (P &lt; .01). Uveoscleral outflow at night was decreased when calculated using tonographic outflow facility but not fluorophotometric outflow facility in the Goldmann equation. All other measurements were unchanged. CONCLUSIONS Significant changes in aqueous humor dynamics at night in healthy mature humans include reductions in aqueous flow, outflow facility, and possibly uveoscleral outflow. Nocturnal changes in IOP are independent of the pneumatonometer probe position and are dependent on an individual's posture during the measurement.Arch Ophthalmol. 2011;129(3):269-275--

The measurement of central corneal thickness (CCT) is vastly useful for diagnostic and therapeutic evaluation. The ultrasound pachymetry is currently the most common CCT technique. This study was undertaken to determine the precision and correlation of measurements obtained by mechanical and ultrasound pachymetry. The ultrasound pachymetry was determined using an A-scan ultrasonic pachymeter. The probe tip was held perpendicular on the central cornea by a support that goes down smooth to avoid excessive pressure and instability. The mechanical pachymetry was determined using a micrometer with a tip of 2mm of diameter. The tip of the micrometer was held perpendicular on the central cornea by a support that keeps stabilized. A 10x optics increase and a digital video camera shows real time image of approach and full contact of the tip with the cornea. Eight human corneas were obtained from cadaveric eyes. Measurements in both systens were taken for three different users, each one performed five readings. The results for both systems has an average SD of 33 microns refers to the systematic error between users (for positioning, center, pinching). But the difference between systems was 120 microns, possibly refers to the imprecision of ultrasound pachymetry in measuring in vitro corneas.

Background and Objective:To investigate the efficacy of anterior segment optical coherence tomography (AS-OCT) for calculating flap thickness in femtosecond laser-assisted laser in situ keratomileusis.Patients and Methods:Fifty-one eyes of 26 patients with myopia and myopic astigmatism were included in this prospective study. High-resolution corneal images were evaluated at 1 week and 1 month postoperatively. Images along the horizontal meridian were measured with the flap tool at seven points.Result:Measurements at vertex and at 1 mm nasally and temporally from the vertex were indistinct but easily defined. Although statistically not significant, flaps were found to be thinner in the central cornea and thicker in the periphery (Measurements at vertex and at 1 mm nasally and temporally from the vertex were indistinct but easily defined. Although statistically not significant, flaps were found to be thinner in the central cornea and thicker in the periphery (P> .05).Conclusion:AS-OCT provides detailed high-resolution images for quantitative evaluation of the flap–stroma relationship, but it may not be precise in the central 2-mm area of the cornea. Despite this, AS-OCT is an imaging tool with significant utility.

The purpose of this study was to assess the corneal response, as measured by corneal oxygen uptake, of keratoconic corneas to SoftPerm and SynergEyes hybrid contact lenses at the central cornea, 2.0 and 4.5 mm temporal to the central cornea, and 1 mm temporal to the limbus.

Corneal antigen‐presenting cells (APC), including dendritic cells (DC), were thought to reside exclusively in the peripheral cornea. Here, we present recent data from our group demonstrating that the central cornea is indeed endowed with a heterogeneous population of epithelial and stromal DC, which function as APC. Although the corneal periphery contains mature and immature resident bone marrow‐derived CD11c+DC, the central cornea is endowed exclusively with immature and precursor DC, both in the epithelium and the stroma, wherein Langerhans cells and monocytic DC reside, respectively. During inflammation, a majority of resident DC undergo maturation by overexpressing major histocompatibility complex class II and B7 (CD80/CD86) costimulatory molecules. In addition to the DC, macrophages are present in the posterior corneal stroma. In transplantation, donor‐derived DC are able to migrate to host cervical lymph nodes and activate host T cells via the direct pathway when allografts are placed in inflamed host beds. These data revise the tenet that the cornea is immune‐privileged as a result of lack of resident lymphoreticular cells and suggest that the cornea is capable of diverse cellular mechanisms for antigen presentation.

In order to understand the pathobiology of neurotrophic keratopathy, we established a mouse model by coagulating the first branch of the trigeminal nerve (V1 nerve). In our model, the sensory nerve in the central cornea disappeared and remaining fibers were sparse in the peripheral limbal region. Impaired corneal epithelial healing in the mouse model was associated with suppression of both cell proliferation and expression of stem cell markers in peripheral/limbal epithelium as well as a reduction of transient receptor potential vanilloid 4 (TRPV4) expression in tissue. TRPV4 gene knockout also suppressed epithelial repair in mouse cornea, although it did not seem to directly modulate migration of epithelium. In a co-culture experiment, TRPV4-introduced KO trigeminal ganglion upregulated nerve growth factor (NGF) in cultured corneal epithelial cells, but ganglion with a control vector did not. TRPV4 gene introduction into a damaged V1 nerve rescues the impairment of epithelial healing in association with partial recovery of the stem/progenitor cell markers and upregulation of cell proliferation and of NGF expression in the peripheral/limbal epithelium. Gene transfer of TRPV4 did not accelerate the regeneration of nerve fibers. Sensory nerve TRPV4 is critical to maintain stemness of peripheral/limbal basal cells, and is one of the major mechanisms of homeostasis maintenance of corneal epithelium.

BackgroundGlaucoma prevalence and subtype profile vary across different racial and ethnic groups. This study provides a comparative evaluation of differences in aqueous humour dynamics (AHD) and ocular biometrics in healthy Chinese and Caucasian adults of two different age groups.MethodsData from two independent studies with identical designs were compared. Cohorts included young adults (20–30 years old, 32 Chinese and 39 Caucasians) and older adults (>50 years old, 37 Chinese and 46 Caucasians). Parameters of AHD and ocular biometrics were evaluated. Group comparisons were made by generalised estimating equation methods.ResultsDifferences in young adult Caucasians compared with similarly aged Chinese were thinner central cornea (−29.27 µm, p<0.001), lower intraocular pressure (IOP) (−2.33 mm Hg, p<0.001), larger anterior chamber volume (ACV) (28.78 µL, p<0.001) and faster uveoscleral outflow rate (Fu) (0.82 µL/min, p<0.001). Differences in older adult Caucasians compared with similarly aged Chinese were slower aqueous flow rate (Fa) (−0.28 µL/min, p=0.042), lower IOP (−1.97 mm Hg, p<0.001) and larger ACV (33.15 µL, p<0.001). Considering all subjects together by race, Caucasian subjects had slower Fa (−0.22 µL/min, p=0.035), thinner corneas (−0.52 µm, p=0.003), lower IOP (−2.11 mm Hg, p<0.001), higher ACV (30.39 µL, p<0.001) and faster Fu (0.63 µL/min, p<0.001).ConclusionDifferences in AHD and biometrics between Caucasian and Chinese adults include larger ACVs which may contribute to the wider angles reported in Caucasians, and slower Fa rates coupled with faster Fu rates which may contribute to their lower IOP and lower overall risk of glaucoma.