A fully automatic nerve segmentation and morphometric parameter quantification system for early diagnosis of diabetic neuropathy in corneal images

Diabetic Peripheral Neuropathy (DPN) is one of the most common types of diabetes that can affect the cornea. An accurate analysis of the nerve structures can assist the early diagnosis of this disease. This paper proposes a robust, fast and fully automatic nerve segmentation and morphometric parameter quantification system for corneal confocal microscope images. The segmentation part consists of three main steps. First, a preprocessing step is applied to enhance the visibility of the nerves and remove noise using anisotropic diffusion filtering, specifically a Coherence filter followed by Gaussian filtering. Second, morphological operations are applied to remove unwanted objects in the input image such as epithelial cells and small nerve segments. Finally, an edge detection step is applied to detect all the nerves in the input image. In this step, an efficient algorithm for connecting discontinuous nerves is proposed. In the morphometric parameters quantification part, a number of features are extracted, including thickness, tortuosity and length of nerve, which may be used for the early diagnosis of diabetic polyneuropathy and when planning Laser-Assisted in situ Keratomileusis (LASIK) or Photorefractive keratectomy (PRK). The performance of the proposed segmentation system is evaluated against manually traced ground-truth images based on a database consisting of 498 corneal sub-basal nerve images (238 are normal and 260 are abnormal). In addition, the robustness and efficiency of the proposed system in extracting morphometric features with clinical utility was evaluated in 919 images taken from healthy subjects and diabetic patients with and without neuropathy. We demonstrate rapid (13 seconds/image), robust and effective automated corneal nerve quantification. The proposed system will be deployed as a useful clinical tool to support the expertise of ophthalmologists and save the clinician time in a busy clinical setting

Short-term impact of glycaemic control and intravitreal ranibizumab treatment on serum cytokine levels and diabetic macular edema in patients with unregulated blood glucose

Objective: To evaluate the short-term effect of glycaemic control and intravitreal ranibizumab treatment on diabetic macular edema (DME) and to assess the correlation between HbA1c and certain serum cytokines. Design: A prospective study of 43 participants with HbA1c levels exceeding 53 mmol/mol (7%) and with DME, as detected by spectral domain optical coherence tomography (SDOCT). Subjects: Participants were grouped according to their initial best corrected distance visual acuity (BCVA). Group 1 was treated with three monthly doses of intravitreal ranibizumab (0.5 mg) injections, and Group 2 was followed without treatment. Methods: Serum cytokine levels, including interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor-alpha (TNF-α), monocyte chemoattractant protein-1(MCP-1), and vascular endothelial growth factor (VEGF) were analysed at the beginning and at the end of 3 months, using enzyme-linked immunosorbent assays (ELISA). Results: A significant decrease in macular thicknesses (except for one quadrant) was observed in Group. Changes in serum cytokine levels were not correlated with HbA1c decrease. Serum VEGF level was significantly increased in Group 1, despite the intravitreal treatment. Conclusion: Short-term glycaemic control alone had limited value in the treatment of DME. The therapeutic effect of intravitreal treatment on DME supports the role of the local cytokine milieu in the pathophysiology

Characteristics of the cornea in patients with pseudoexfoliation syndrome

ABSTRACT Purpose: To quantify the morphological alterations in corneal nerve fibers and cells in patients with pseudoexfoliation syndrome (PEX) and their relationship with the presence of hyperreflective endothelial deposits observed using in vivo confocal microscopy. Methods: One eye each of 37 patients with PEX and 20 age-matched healthy control subjects was evaluated by in vivo corneal confocal microscopy. Patients with PEX were further classified into two groups: those with and without hyperreflective endothelial deposits. We evaluated the densities of basal epithelial cells, anterior and posterior stromal keratocytes, and endothelial cells and structure of sub-basal nerve fibers. Results: The mean anterior and posterior stromal keratocyte and endothelial cell densities and corneal sub-basal nerve plexus variables were significantly lower in patients with PEX compared with those in healthy control subjects. The mean basal epithelial cell density did not significantly differ. Conclusion: Eyes with PEX presented decreased corneal sub-basal nerve plexus variables and cell densities in all corneas, except for the mean basal epithelial cell density. Further, a trend of lower corneal sub-basal nerve plexus measurements in patients with hyperreflective endothelial deposits compared with those without endothelial deposits was observed

Corneal Sensitivity and Dry Eye Symptoms in Patients with Keratoconus.

PURPOSE: To investigate corneal sensitivity to selective mechanical, chemical, and thermal stimulation and to evaluate their relation to dry eye symptoms in patients with keratoconus. METHODS: Corneal sensitivity to mechanical, chemical, and thermal thresholds were determined using a gas esthesiometer in 19 patients with keratoconus (KC group) and in 20 age-matched healthy subjects (control group). Tear film dynamics was assessed by Schirmer I test and by the non-invasive tear film breakup time (NI-BUT). All eyes were examined with a rotating Scheimpflug camera to assess keratoconus severity. RESULTS: KC patients had significatly decreased tear secretion and significantly higher ocular surface disease index (OSDI) scores compared to controls (5.3+/-2.2 vs. 13.2+/-2.0 mm and 26.8+/-15.8 vs. 8.1+/-2.3; p0.05). The mean threshold for selective mechanical (KC: 139.2+/-25.8 vs. control: 109.1+/-24.0 ml/min), chemical (KC: 39.4+/-3.9 vs. control: 35.2+/-1.9%CO2), heat (KC: 0.91+/-0.32 vs. control: 0.54+/-0.26 Delta degrees C) and cold (KC: 1.28+/-0.27 vs. control: 0.98+/-0.25 Delta degrees C) stimulation in the KC patients were significantly higher than in the control subjects (p0.05), whereas in the control subjects both mechanical (r = 0.52, p = 0.02), chemical (r = 0.47, p = 0.04), heat (r = 0.26, p = 0.04) and cold threshold (r = 0.40, p = 0.03) increased with age. In the KC group, neither corneal thickness nor tear flow, NI-BUT or OSDI correlated significantly with mechanical, chemical, heat or cold thresholds (p>0.05 for all variables). CONCLUSIONS: Corneal sensitivity to different types of stimuli is decreased in patients with keratoconus independently of age and disease severity. The reduction of the sensory input from corneal nerves may contribute to the onset of unpleasant sensations in these patients and might lead to the impaired tear film dynamics

Corneal Confocal Microscopy to Image Small Nerve Fiber Degeneration: Ophthalmology Meets Neurology.

Neuropathic pain has multiple etiologies, but a major feature is small fiber dysfunction or damage. Corneal confocal microscopy (CCM) is a rapid non-invasive ophthalmic imaging technique that can image small nerve fibers in the cornea and has been utilized to show small nerve fiber loss in patients with diabetic and other neuropathies. CCM has comparable diagnostic utility to intraepidermal nerve fiber density for diabetic neuropathy, fibromyalgia and amyloid neuropathy and predicts the development of diabetic neuropathy. Moreover, in clinical intervention trials of patients with diabetic and sarcoid neuropathy, corneal nerve regeneration occurs early and precedes an improvement in symptoms and neurophysiology. Corneal nerve fiber loss also occurs and is associated with disease progression in multiple sclerosis, Parkinson's disease and dementia. We conclude that corneal confocal microscopy has good diagnostic and prognostic capability and fulfills the FDA criteria as a surrogate end point for clinical trials in peripheral and central neurodegenerative diseases

Topology-aware Quality-of-Service Support in Highly Integrated Chip Multiprocessors

Current design complexity trends, poor wire scalability, and power limitations argue in favor of highly modular onchip systems. Today’s state-of-the-art CMPs already feature up to a hundred discrete cores. With increasing levels of integration, CMPs with hundreds of cores, cache tiles, and specialized accelerators are anticipated in the near future. Meanwhile, server consolidation and cloud computing paradigms have emerged as profit vehicles for exploiting abundant resources of chip-multiprocessors. As multiple, potentially malevolent, users begin to share virtualized resources of a single chip, CMP-level quality-of-service (QOS) support becomes necessary to provide performance isolation, service guarantees, and security. This work takes a topology-aware approach to on-chip QOS. We propose to segregate shared resources, such as memory controllers and accelerators, into dedicated islands (shared regions) of the chip with full hardware QOS support. We rely on a richly connected Multidrop Express Channel (MECS) topology to connect individual nodes to shared regions, foregoing QOS support in much of the substrate and eliminating its respective overheads. We evaluate several topologies for the QOSenabled shared regions, focusing on the interaction between network-on-chip (NOC) and QOS metrics. We explore a new topology called Destination Partitioned Subnets (DPS), which uses a light-weight dedicated network for each destination node. On synthetic workloads, DPS nearly matches or outperforms other topologies with comparable bisection bandwidth in terms of performance, area overhead, energyefficiency, fairness, and preemption resilience.

Corneal confocal microscopy detects a reduction in corneal endothelial cells and nerve fibres in patients with acute ischemic stroke

YesEndothelial dysfunction and damage underlie cerebrovascular disease and ischemic stroke. We undertook corneal confocal microscopy (CCM) to quantify corneal endothelial cell and nerve morphology in 146 patients with an acute ischemic stroke and 18 age-matched healthy control participants. Corneal endothelial cell density was lower (P<0.001) and endothelial cell area (P<0.001) and perimeter (P<0.001) were higher, whilst corneal nerve fbre density (P<0.001), corneal nerve branch density (P<0.001) and corneal nerve fbre length (P=0.001) were lower in patients with acute ischemic stroke compared to controls. Corneal endothelial cell density, cell area and cell perimeter correlated with corneal nerve fber density (P=0.033, P=0.014, P=0.011) and length (P=0.017, P=0.013, P=0.008), respectively. Multiple linear regression analysis showed a signifcant independent association between corneal endothelial cell density, area and perimeter with acute ischemic stroke and triglycerides. CCM is a rapid non-invasive ophthalmic imaging technique, which could be used to identify patients at risk of acute ischemic stroke.Qatar National Research Fund Grant BMRP2003865

Subfoveal Choroidal Thickness Changes in Patients Who Underwent Inferior Oblique Myectomy Surgery

Amaç: Alt oblik kasın aşırı fonksiyonu tedavisi için alt oblik miyektomi cerrahisi uygulanan olgularda subfoveal koroid kalınlığı değişikliklerinin spektral domain-optik koherans tomografi ile değerlendirilmesi.Gereç ve Yöntem: Alt oblik miyektomi cerrahisi uygulanan 32 olgu bu prospektif çalışmaya dahil edildi. Bilateral cerrahi yapılan 15 olgunun sağ gözleri çalışmaya alınırken, tek taraflı cerrahi uygulanan 17 olgunun iki gözü de çalışmaya dahil edildi ve cerrahi yapılmayan gözler kontrol olarak alındı. Olguların subfoveal koroid kalınlığı ölçümleri spektral domain-optik koherans tomografi cihazının artırılmış derinlikli görüntüleme modunda, cerrahi öncesi ve cerrahi sonrası 1. gün, 1. hafta ve 1. ay olmak üzere 4 defa kaydedildi. Cerrahi öncesi ve sonrası kaydedilen subfoveal koroid kalınlığı değerleri arasındaki farklılıkların karşılaştırılmasında tekrarlı ölçümlerde varyans analizi testi kullanıldı.Bulgular: Olguların ortalama yaşı 10,8 5,9 yıl idi. Alt oblik miyektomi cerrahisi uygulanan gözlerde ortalama subfoveal koroid kalınlığı değerlerinin cerrahi öncesine göre cerrahi sonrası 1. gün ve 1. haftada anlamlı olarak artmış olduğu (sırasıyla p0,008 ve p0,009), 1. ayda ise subfoveal koroid kalınlığı değerlerinin azaldığı ve cerrahi öncesine göre anlamlı fark kalmadığı gözlendi (p0,176). Kontrol grubundaalınan 4 ölçüm arasında anlamlı farklılık olmadığı görüldü (p0,351).Sonuç: Alt oblik miyektomi cerrahisi uygulanan gözlerde geçici bir süre subfoveal koroid kalınlığı artışı olduğu tespit edilmiştir. Cerrahiişlemler sırasında kas traksiyonunun mekanik etkisinin bu sonuca yol açtığı düşünülebilir.Objective: To evaluate the subfoveal choroidal thickness changes in patients with inferior oblique overaction who underwent inferior oblique myectomy surgery by using spectral-domain optical coherence tomography. Material and Method: Thirty-two patients with inferior oblique overaction who underwent inferior oblique myectomy procedure were enrolled in this prospective study. Right eyes of 15 patients who had bilateral surgery and both eyes of 17 patients who had unilateral surgery were included in analysis, with the fellow eyes serving as controls. Subfoveal choroidal thickness was measured preoperatively and 1 day, 1 week, and 1 month postoperatively using the enhanced depth imaging program of an spectral-domain optical coherence tomography. Repeated measures ANOVA test was used to compare the subfoveal choroidal thickness data among the preoperative and postoperative measurements. Results: The mean age of the patients was 10.8 ± 5.9 years. The mean subfoveal choroidal thickness increased significantly at 1-day and 1-week visits (p0.008 and p0.009, respectively) compared with the preoperative data in eyes receiving inferior oblique myectomy surgery, while no significant difference was present 1 month after surgery (p0.176). There were no significant differences in subfoveal choroidal thickness of the fellow eyes among the four visits (p0.351). Conclusion: A transient increase in subfoveal choroidal thickness was observed in eyes receiving inferior oblique myectomy surgery. This finding may be due to the mechanical effect as a result of muscle traction during the surgical procedures

Iatrogenic Lens Injuries

During intraocular surgery, undesired damages of various etiology may occur in adjacent tissues. One of these tissues is the crystalline lens, which may be traumatized both in anterior segment and posterior segment surgeries, and when damaged, it usually causes marked decrease in visual acuity. The leading causes of iatrogenic lens injuries are intravitreal injection, laser iridotomy, phakic intraocular lens implantation, anterior chamber paracentesis, and vitreoretinal surgery. When crystalline lens damage occurs, its negative effect on visual function may be eliminated by performing cataract surgery intraoperatively or in elective conditions. (Turk J Ophthalmol 2012; 42: Supplement 27-30