Medical Hypothesis, Discovery & Innovation (MEHDI) Journals
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COVID-19: Preliminary Clinical Guidelines for Ophthalmology Practices
No full textThe zoonotic Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and its resultant human coronavirus disease (COVID-19) recently appeared as a global health threat that can cause severe respiratory infection and terminal respiratory distress. By the first week of April, more than 1.3 million people had been globally infected and more than 70,000 had lost their lives to this contagious virus. Clinical manifestations occur shortly after exposure, or a few days later. There is controversy regarding the transmission of the virus through the tear and conjunctiva; however, there are reports that the ocular surface might be a potential target for COVID-19. The ease of transmission of this virus at close proximity presents a risk to eyecare workers. Several recommendations have been issued by local and national organizations to address the issue of safe ophthalmic practice during the ongoing COVID-19 pandemic. These guidelines have numerous similarities; however, subtle differences exist. The purpose of this paper was to discuss measures, with a specific focus on standard precautions, to prevent further dissemination of COVID-19 at Eye Clinics. We have proposed procedures to triage suspected cases of COVID-19, considering emergency conditions.Photo Courtesy of Majid Moshirfar, MD FACS
The Antiangiogenic Properties of Adipose-Derived Mesenchymal Stem/Stromal Cells in Corneal Neovascularization in a Rabbit Model
Full text linkThe purpose was to study the anti-angiogenic effect of adipose-derived mesenchymal stem/stromal cells (ADMSCs) on experimentally induced corneal injuries. Corneal neovascularization (NV) was induced by incising and subsequently suturing the corneal surface in 32 New Zealand rabbits. Following suturing, the rabbits were randomly allocated into 2 groups, and received either phosphate-buffered saline (PBS) (control) or ADMSCs, both administered via three different routes. Digital images of the cornea were obtained two weeks post-incision to measure the area of neovascularized cornea. Tumor necrosis factor (TNF) was immunohistochemically assessed in the both groups. The corneal tissue was evaluated for vascular endothelial growth factor (VEGF). The extent of corneal NV in all eyes was assessed photographically by an independent observer. Fourteen days after the incisions, the degree of corneal NV was substantially decreased in the ADMSC-treated group (1.87 ± 0.9 mm2, 1.4 % ± 0.67 % of corneal surface) compared to the control and PBS-treated group (4.66 ± 1.74 mm2, 3.51 % ± 1.31 %, p < 0.001). ADMSCs significantly decreased injury-induced corneal NV in New Zealand rabbits two weeks post-treatment. This strategy has potential for use in the control of corneal NV in vivo.
Oculocardiac Reflex During Intravitreal Injection
Full text linkOculocardiac reflex (OCR) has been described to occur with mechanical manipulation of the eye, eyelids or orbit. There are no reports in the literature of OCR during intravitreal injection (IVI). This may be due to the fact that heart rate is not monitored during the procedure. We aimed to evaluate OCR during IVI. A total of 532 patients were enrolled in the study in Asociacion para Evitar la Ceguera en Mexico. Mexico City, Mexico. IVI was performed on one eye in every patient with diabetic retinopathy (DR), age related macular degeneration (AMD) or choroidal neovascularization (CNV) secondary to pathological myopia. Heart rate was monitored with a pulse oximeter before, during and after injection. OCR was defined as a 20% decrease or more of basal heart rate. The population enrolled included 270 females and 262 males with mean age of 63.8 years. A decrease in heart rate of 20% or more occurred in 18 patients during IVI (3.3%; 95% confidence interval 1.85% and 4.92%). OCR was asymptomatic in these patients. OCR occurred in 3.3% of our patients during IVI. Hence, OCR must be considered when performing IVI
A Review of Last Decade Developments on Epiretinal Membrane Pathogenesis
Full text linkEpiretinal membrane (ERM) is a pathologic tissue that develops at the vitreoretinal interface. ERM is responsible for pathological changes of vision with varying degrees of clinical significance. It is either idiopathic or secondary to a wide variety of diseases such as proliferative diabetic retinopathy (PDR) and proliferative vitreoretinopathy (PVR). A great variation in the prevalence of idiopathic ERM among different ethnic groups proposed that genetic and lifestyle factors may play a role in ERM occurrence. Histopathological studies demonstrate that various cell types including retinal pigment epithelium (RPE) cells, fibrocytes, fibrous astrocytes, myofibroblast-like cells, glial cells, endothelial cells (ECs) and macrophages, as well as trophic and transcription factors, including transforming growth factor (TGF), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) etc., are directly or indirectly involved in the pathogenesis of idiopathic or secondary ERMs. These processes are driven (on the last count) by more than 50 genes, such as Tumor Necrosis Factor (TNF), CCL2 ((chemokine (C-C motif) ligand 2)), MALAT1, transforming growth factor (TGF)-β1, TGF-β2, Interleukin-6 (IL-6), IL-10, VEGF and glial fibrillary acidic protein (GFAP), some of which have been studied more intensely than others. The present paper tried to summarize, highlight and cross-correlate the major findings made in the last decade on the function of these genes and their association with different types of cells, genes and gene expression products in the ERM formation
Peripheral Cornea Crosslinking Before Deep Anterior Lamellar Keratoplasty
No full textSince Cornea crosslinking (CXL) has been proven to halt progression and biomechanically stabilize keratoconus, we hypothesized that CXL of the corneal periphery 3 months prior to corneal transplantation can reduce the incidence of recurrent ectasia by strengthening the peripheral corneal tissue and causing apoptosis of diseased peripheral host keratocytes. Thus, the aim of this case-repot was to propose a novel peripheral CXL technique prior to keratoplasty and evaluate its safety. A 22-year-old woman was admitted with advanced right keratoconus and corrected distance visual acuities of 20/30 in the right eye and 20/200 in the left eye with a manifest refraction of -3.00 -8.00 × 36 and -17.00 -11.50 × 90, respectively. The proposed treatment involved crosslinking of peripheral corneal tissue (6.5-9.5mm), sparing the central cornea and limbus, three months prior to corneal transplantation as a means of biomechanically strengthening the peripheral cornea tissue. We performed peripheral CXL technique in a patient with keratoconus undergoing deep anterior lamellar keratoplasty (DALK). This procedure was feasible and safe with repopulation of the peripheral cornea with keratocytes and no significant endothelial cell loss. This method might reduce or eliminate the need for repeat corneal transplantation in patients with recurrent ectasia. Further studies are needed to confirm the results
Advances in Biomechanical Parameters for Screening of Refractive Surgery Candidates: A Review of the Literature, Part III
Full text linkCorneal biomechanical properties have garnered significant interest in their relation to the development of ectatic corneal disease. Alongside the advent of corneal tomography and Scheimpflug imaging such as Pentacam and Galilei, there have been advances in assessing the cornea based on its biomechanical characteristics. Though the aforementioned imaging systems are highly capable of identifying morphologic abnormalities, they cannot assess mechanical stability of the cornea. This article, in contrast to Parts I and II of this article series, will focus on in vivo corneal biomechanical imaging systems. The two most readily available commercial systems include the Corvis ST and the Ocular Response Analyzer. Both of these systems aimed to characterize corneal biomechanics via distinct measurements. While in Parts I and II of this article series the authors focused on elevation, pachymetric, and keratometric data, the purpose of this article was to summarize biomechanical parameters and their clinical use in screening refractive surgery candidates. Moreover, this article explores biomechanical decompensation and its role in the development of corneal ectasia and keratoconus. There is a focus on the diagnostic accuracy of biomechanical indices in the identification of diseases such as keratoconus that may preclude a patient from undergoing refractive surgery
Conjunctival Autograft With Fibrin Glue for Pterygium: A Long Term Recurrence Assessment
Full text linkPterygium is an old challenge for ophthalmic surgeons. Its final resolution is surgical intervention. New surgical techniques have been introduced to improve the outcome, however, the possibility of recurrence always exists. The purpose of this study was to evaluate the pterygium recurrence rate with a long-term follow-up, after surgery was performed with conjunctival autograft and fibrin glue as a biological adhesive. A retrospective case-series study was performed, reviewing cases operated from May 2008 to May 2018 with at least 1 year of follow-up in a private clinic in Buenos Aires, Argentina. The evaluation time-points were at 1 day, 20 days, 6 months, 1 year after surgery and then every year. All the procedures were performed by the same surgeon in single center. Topical Mitomycin C (MMC), 5-Fluorouracil (5-FU), cauterization and/or amniotic membrane were not used in any case. From a total of 159 operated eyes (82/77 women/men), pterygium was recurred in 7 eyes (4.4%); all of them detected at the second follow-up time-point (at day 20). Intraoperative complications did not occur, but at the postoperative stage, one case presented a conjunctival granuloma, which was surgically resolved. In conclusion, a low pterygium recurrence rate was observed after conjunctival autograft with fibrin glue. In our study, recurrence was found at the postoperative first month and did not recur until the end of follow-up for 10 years. Epub: October 1, 2019
Comparison of Corneal Epithelial Thickness Map Measured by Spectral Domain Optical Coherence Tomography in Healthy, Subclinical and Early Keratoconus Subjects
Full text linkThe aim of this study was to compare epithelial thickness map obtained by Spectral Domain Optical Coherence Tomography (SD-OCT) of eyes with myopic astigmatism but without keratoconus, subclinical and early keratoconus. Sixty-three eyes divided into three groups; myopic astigmatism without keratoconus, subclinical and early keratoconus. Corneal epithelial thickness map was obtained by SD-OCT for all patients and compared between the 3 groups. Mean epithelial thickness in the area of minimum corneal epithelial thickness, in the one eighth part of the inferior (I) and in the one eighth part of the temporal (T) were 56.64±2.82 µm, 59.00±3.24 µm and 60.40±4.93 µm respectively in subclinical group. Three parameters on epithelial maps obtained by SD-OCT was significantly different in the 2 groups: I and T corneal epithelial thickness map was thicker in subclinical keratoconus (P<0.02 and P<0.02 respectively). Epithelial map uniformity indices were different between the groups, as Superior-I, Superonasal-Inferotemporal were lower (P<0.00 and P< 0.01 respectively) but T-nasal was higher in the subclinical group (P<0.02). The area with minimum epithelial thickness had a significantly lower amount in early keratoconus group compared to the other two groups (P<0.00). In conclusion, corneal epithelial thickness map provided early detection of keratoconus in the subclinical stage with compensatory epithelial thickening of inferior and temporal one eighth compared to total corneal thickness and changes in epithelial map uniformity indices cause early detection of subclinical keratoconus from normal cornea
A Modified Customized Rigid Gas Permeable Contact Lens to Improve Visualization During Phacoemulsification in Ectatic Corneas
Full text linkAdvanced Keratoconus and ectatic corneal diseases may lead to corneal thinning and irregular astigmatism. The optical distortion caused by these pathologies may result in poor visibility for the surgeon during phacoemulsification operations. Thus, the risk of complication would be increased intraoperatively (capsular rupture, vitreous loss). The aim of this case series was to use Rigid Gas Permeable (RGP) contact lens to improve visualization during all the stages of phacoemulsification surgery in irregular corneas and to avoid open sky technique for cataract removal during penetrating keratoplasty. A customized, 12 mm, RGP contact lens was designed and manufactured. Two peripheral notches were customized to fit the hand position of the surgeon (at 11 O’clock and 2 Clock in this case series) to allow clear corneal incisions. Six eyes of 6 patients were included (3 eyes with advanced keratoconus and a severely optically distorted, yet clear corneas, planned for penetrating keratoplasty on the same day; 2 eyes were status post-intracorneal ring segment implantation for stage 4 keratoconus and 1 eye had combined phacoemulsification with superficial keratectomy to remove paracentral corneal Salzmann’s nodule). Lens opacities ranged from +2 to +4 nuclear sclerosis in all eyes. Good visualization of the anterior lens and capsule attained with the RGP contact lens fitting. Improved visualization was reported during all the steps (Capsulorhexis, IA, Phaco. IOL implantation). The phacoemulsification was smooth and non-complicated in a total of 6 eyes of 6 patients. In these cases, without RGP fitting, the operation was not technically possible. The customized notches allowed any insertion of surgical instruments, and with the help of viscoelastic maintained a good stability of the contact lens during the operation. We concluded that customized method Rigid Gas Permeable contact lens, may help reducing complications during phacoemulsification in advanced corneal ectasia and perhaps in irregular corneas as well