A two-compartment model of the human retina

Summary Purpose: In this article we question a basic concept in retinal pathology, which views the retina as composed primarily of neural elements, in a single compartment. Methods: We suggest an alternative approach, centering on the epithelial-glial elements of the retina, dividing the retina into two distinct compartments. The framework of these two compartments is composed of two epithelial-like monostratified cell layers facing each other by their apical surfaces. This model is in agreement with the embryological development of the retina. Results: Each compartment is composed of a monostratified cell layer in which neural elements are embedded and each is supplied by a different blood supply. The inner compartment, also referred to as the Muller cell compartment, extends between the inner and outer limiting membranes. The outer, or RPE, compartment extends between the outer limiting and Bruch's membranes. The border between the two compartments is formed by the outer limiting membrane (OLM). One simplified example utilizing the two-compartment concept is as follows: inner compartment edema (inner blood-retinal barrier breakdown) may manifest as cystoid edema, but not as serous retinal detachment, while outer compartment edema (outer blood-retinal barrier breakdown) may manifest as serous retinal detachment but not as cystoid edema, as long as the integrity of the OLM is maintained. Conclusion: A two-compartment approach to the structure of the retina, centering on non-neural elements, may enhance our understanding of some retinal pathologies. Various retinal diseases, mainly of vascular origin, are limited to one of the two compartments

A Proposal for the Use of a Fixed Low-Energy Selective Laser Trabeculoplasty for Open Angle Glaucoma

Selective laser trabeculoplasty (SLT) has been in routine clinical use for over 20 years with millions of patients successfully treated and a low rate of clinically significant complications. The procedure requires the clinician to manually position the laser beam on the trabecular meshwork using a gonioscopy lens and to titrate the SLT laser energy based on the amount of pigmentation in the angle, as well as the observation of small bubbles produced by the laser effect. We propose that SLT energy titration is unnecessary either to achieve intraocular pressure (IOP) reduction or to minimize potential side effects. Ample evidence to support our proposal includes multiple clinical reports demonstrating comparable levels of IOP reduction resulting from different laser energies, a large variety of energy and other laser parameters used in commercially available SLT lasers, and the nature of the laser-induced changes in the trabecular meshwork tissue with respect to energy. Despite these variations in laser parameters, SLT consistently reduces IOP with a low complication rate. We propose that using low fixed energy for all patients will effectively and safely lower patients\u27 IOP while reducing the complexity of the SLT procedure, potentially making SLT accessible to more patients

Direct Selective Laser Trabeculoplasty in Open Angle Glaucoma Study Design: A Multicentre, Randomised, Controlled, Investigator-Masked Trial (GLAUrious)

Introduction: Laser trabeculoplasty is an effective and widely used treatment for glaucoma. A new laser technology, the Eagle direct selective laser trabeculoplasty (DSLT) device, may provide automated, fast, simple, safe and effective laser treatment for glaucoma in a broader range of clinical settings. This trial aims to test the hypothesis that translimbal DSLT is effective and not inferior to selective laser trabeculoplasty (SLT) in reducing intraocular pressure (IOP) in open angle glaucoma (OAG). Methods and analysis: This is a multicentre, randomised, controlled, investigator-masked study. The primary efficacy outcome is intergroup difference in mean change from baseline IOP measured at 6 months. Secondary outcomes include mean percentage reduction in IOP at 3, 6 and 12 months; proportion of participants with at least 20% reduction in IOP from baseline at 6 months; change in ocular hypotensive medications at 12 months and evaluation of safety. Participants were aged \u3e= 40 years with OAG, including exfoliative or pigmentary glaucoma, or ocular hypertension with untreated or washed out IOP 22-35 mm Hg. Treatments: DSLT: 120 shots, 3 ns, 400 µm spot size, energy 1.4-1.8 mJ delivered at the limbus over 2 s. SLT: approximately 100 shots, 3 ns, 400 µm spot size administered 360 degrees at the limbus using any gonioscopy lens, energy 0.3-2.6 mJ. A sample size of 164 is sufficient to detect a non-inferiority margin of 1.95 mm Hg for change from baseline IOP. Clinical trial registration number: NCT03750201, ISRCTN14033075

Causative Pathogens in Endophthalmitis after Intravitreal Injection of Anti-vascular Endothelial Growth Factor Agents

Intravitreal injection of anti-vascular endothelial growth factor is currently the preferred treatment for several posterior segment diseases, including age-related macular degeneration and diabetic retinopathy, as well as macular edema and retinal vein occlusion. As an invasive procedure it involves risks. The most significant risk is infectious endophthalmitis, a sight-threatening and even a globe-threatening acute fulminant condition. Most common pathogens include Streptococcus and Staphylococcus species, surprisingly originating from the patient’s, surgeon’s, or nurse’s mouth. Infectious endophthalmitis may have devastating and irreversible effect, with Streptococcus-induced cases having the worst visual outcome. It is therefore crucial for clinicians to promptly recognize and treat such conditions, and, far more important, to put in place protective and preventive measures against this rare, but sight-threatening complication. To that end, this paper describes the most common pathogens causing endophthalmitis after IVI of anti-VEGF, and defines their source, to aid the physician in developing strategies to prevent this catastrophic infection

Hydration with Cefuroxime-a method for sealing a small leaking corneal perforation

Letter to the edito