Medical Hypothesis, Discovery & Innovation (MEHDI) Journals
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Developmental Changes in Accommodation Evidenced by an Ultrabiomicroscopy Procedure in Patients of Different Ages
Get PDFWe demonstrate that changes in the behaviour of the contractile ciliary muscle accompanied by augmented rigidity of the lens are the most important aspects in the loss of accommodation. With ultrabiomicroscopy (UBM), we demonstrated that the performance of the ciliary muscle is diminished and accompanied by rigidity of the lens. Both lens thickness and trabecular-ciliary process distance (TCPD) were the parameters that showed major alterations with the loss of accommodation in patients of different ages. The results indicated that the differences between these parameters in farsightedness and nearsightedness in the different groups of patients were positively correlated
Glycosylation End-product Formation in Retinal Membranes, an Energy Alteration Injury
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Serous Pigment Epithelium Detachment Associated with Age-Related Macular Degeneration: A Possible Treatment Approach
Get PDFTo evaluate the effects of intravitreal triamcinolone acetonide (TA) as a monotherapy of serous Pigment Epithelial Detachment (PED) associated with AMD (Age-Related Macular Degeneration), this study has been performed. Seventeen patients (19 eyes) with serous PED associated with AMD were observed. All patients received 0.1ml (4mg) of intravitreal TA. The mean follow-up period was 18 months. Re-attachment of serous PED was observed in 37% of cases to the end of follow-up. In other cases, the height and length of serous PED significantly decreased. Visual acuity remained stable in all cases. No evidence of RPE tear or CNV development were noted. Before TA administration, intraocular pressure (IOP) was 20.18 ± 2.58 mmHg however, after intravitreal TA, IOP increased gradually and reached its maximum of all period of observation (23.25±1.85mmHg) six months after injection (P=0.031). In 7 (37%) of the cases, progression to cataract was observed after treatment. After surgery, the visual acuity in all cases increased by 0.2 to 0.5. As a conclusion, intravitreal TA decreases of both the height and length of serous PED associated with AMD after 18 months follow-up in most cases. The presented data provides support for the hypothesis regarding the possibility of monotherapy of serous PED with intravitreal TA
Collagen-Based Bioengineered Substitutes of Donor Corneal Allograft Implantation: Assessment and Hypotheses
No full textTo fabricate donor corneal substitutes based on carbodiimide cross-linked porcine collagen, to study their in vitro and in vivo properties, and to elaborate new implantation techniques for the donor corneal collagen-based substitutes, this study had been performed. Bioengineered substitutes of corneal stroma (BSCS) were fabricated by cross-linking porcine type I collagen with 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide and N-hydroxysuccinimide, as previously described. Their refractive indices were measured using an Abbe refractometer. The mechanical properties were evaluated by their ability to tolerate interrupted stitches placed during deep lamellar keratoplasty performed on isolated rabbit eyes. BSCS were then implanted into one cornea of 8 rabbits and were followed-up for 12 months. Our BSCS had refractive indices of 1.24-1.3 (human cornea 1.37-1.38), and tolerated the placement of 12 interrupted stitches well. A new technique, the BSCS “stitchless” implantation, was developed. When implanted into rabbit corneas, BSCS remained stably integrated and clear during the 12 month follow-up. Non-intensive opacities within corneal layers (grade 1.5 on a scale of 0 to 4) were observed in 2/8 eyes during the 1st postoperative week, and in one eye the opacity resolved. In the 2nd eye a fine opacity (grade 1) remained. Light microscopy confirmed the integrity of the implants and the absence of inflammation in corneal stroma. The current data suggest that the BSCS fabricated in the Ukraine by cross-linking collagen is a good alternative to human donor corneas if medical grade porcine collagen is used. In addition, the new “stitchless” technique of BSCS implantation may decrease corneal substitute damage and accelerate its epithelialisation
Presbyopia: a New Potential Pharmacological Treatment
Get PDFPresbyopia occurs after 40 years of age in humans with a progressive loss of accommodation. Accommodation depends on the contraction of the ciliary muscle and iris, lens changes and convergence. The parasympathetic system regulates the degree of ciliary muscle and iris contraction necessary to modify the shape and position of the lens and its stimulation is effective through the activation of muscarinic receptors that are present in both structures. The hypothesis proposed here suggests the correction of accommodation in emmetropic presbyopic patients using a pharmacological treatment that includes a cholinergic agent combined with non-steroidal anti-inflammatory drugs (NSAIDs). This drug combination can restore near vision without affecting distance vision. It is important to note that the pharmaceutical form used was devoid of any inflammatory or other collateral effects
Diabetic Retinopathy and Ehrlichia: the Possible Relationship
Get PDFIn the United States, 20,000 patients each year lose their sight from diabetic retinopathy. The cause has been attributed to a failure of control of glucose levels. Recent studies have challenged this, and have suggested that there is no evidence for a consistent glycemic threshold in various populations relating to the incidence of retinopathy. The Ehrlichia have been recently suggested as having a role in diabetes. The action of this obligate parasitic bacterium which often affects the cells involved in immunity has the potential of affecting various tissues randomly. This includes self-reactive T or B cells which may be erroneously altered or released from the marrow because of infection of marrow precursors by an Ehrlichia. The discovery of a gene obtained by molecular methodology from a leukemia patient, has given us a tool to identify by molecular methods, the presence of this gene and assumed bacterium in the blood of patients with various syndromes that includes diabetes. Because of the inconsistent evidence of a uniform glycemic threshold in retinopathy and the failure of its control, this hypothesis raises the question of something else that might be causing this damage. The suspected bacterium in diabetes may have as a significant side effect of its infection of the immune system, specifically the site of action of damage to the small vessels of the retina which could lead to what is regularly described in retinopathy; further, and that may include damage to other vessels seen in peripheral and coronary arteries. The availability of a molecular test in whole blood specimens from diabetics suggests a survey for the gene of the bacterium described in diabetic patients and matched controls. Such an investigation could lead to other therapies directed against the bacterium's presence in the marrow if discovered, and strategies to eliminate the harmful self-reactive T or B cells, if found in diabetes
Fibrin Glue Assisted Trans-Scleral Fixation of an Endocapsular Device for Sutureless Trans-Scleral Capsular Bag Fixation in Traumatic Subluxations: The Glued Endocapsular Ring/Segment
Get PDFSubluxated cataracts secondary to blunt injury are a challenge to treat from the construction of rhexis to IOL insertion. For that reason, we designed a new glued endocapsular ring (ECR)/ segment (ECS) for subluxated cataracts and IOLs for sutureless fibrin glue assisted trans-scleral fixation of the capsular bag. The glued ECR/segment stabilizes the capsular bag intra and post-operatively, allowing for sutureless fibrin glue assisted trans-scleral fixation. The segment gives vertical, horizontal and rotational stability as well as forniceal expansion. The advantages to this approach include easier implementation; faster surgery; easy adjustability; sturdier scleral fixation; fewer chances of segment drop into vitreous and lack of suture-related complications. Our hypothesis is that a glued versus sutured ECR/ECS will be more viable and stable on the sclera in the long term. Less pseudophakodonesis will also lead to a more stable capsule-bag complex and reduce the risk of posterior segment complications such as retinal detachment and cystoid macular edema. The nature of the device also makes its removal, if required, much more straightforward than the sutured rings/segments. This device can be used in patients with subluxated cataracts, colobomatous lens or subluxated IOLs
Was Terson's Tersons?
Get PDFTerson’s syndrome has had multiple definitions. The original definition is unlikely to have included Terson’s original case. An updated definition based on mechanism is proposed and related to the original case described by Terson
A Novel Insight into Keratoconus: Mechanical Fatigue of the Cornea
Get PDFAn integrated model for keratectasia risk assessment has received much attention over many years. The objective of this article is to propose a more complete, conceptual model by which high risk individuals can be screened, even with no topographic irregularity or corneal thinning. In this model, corneal ectasia results from the fatigue effect of cyclic shear stress and tensile stress, caused by eye rubbing and fluctuating intraocular pressure (IOP), respectively, on corneal microstructures. The model clarifies the importance of the magnitude of shearing force applied by eye rubbing, the amplitude of IOP fluctuations, the frequency of eye rubbing and IOP fluctuations, the geometry of the cornea, the temperature of the cornea, and the effects of oxidative stress on the cornea in keratectasia development. Therefore, preoperative screening strategies based on these concepts can be designed to assess the risk of keratectasia at an early stage, and select the best candidates who can benefit from keratorefractive surgeries