Background: Retinopathy of prematurity (ROP) is considered as the most common reason for blindness in children, particularly in preterm infants. The disease is characterized by the dysregulation of angiogenic mechanisms due to preterm birth, leading ultimately to vascular abnormalities and pathological neovascularization (NV). Retinal detachment and vision loss could represent a concrete risk connected to the most severe forms of ROP, also characterized by inflammation and retinal cell death.
Methods: During the last decades, many animal models of oxygen-induced retinopathy (OIR) have been recognized as useful tools to study the mechanisms of disease, since they reproduce the hallmarks typical of human ROP. Indeed, modulation of retinal vascular development by exposure to different oxygen protocols is possible in these animals, reproducing the main pathological phenotypes of the disease. The easy quantification of abnormal NV and the possibility to perform electrophysiologic, histological and molecular analyses on these models, make OIR animals a fundamental instrument in studying the pathophysiology of ROP and the effects of novel treatments against the disease.
Discussion: Here, the most commonly used OIR protocols in rodents, such as mice and rats, are described as well as the main pathological outcomes typical of these models. Despite their limitations and variables which should be considered whilst using these models, OIR models display several characteristics which have also been confirmed in human patients, validating the usefulness of such animals in the pre-clinical research of ROP.
Background: Axonal degeneration caused by damage to the optic nerve can result in a gradual death of retinal ganglion cells (RGC), leading to irreversible vision loss. An example of such diseases in humans includes optic nerve degeneration in glaucoma. Glaucoma is characterized by the progressive degeneration of the optic nerve and the loss of RGCs that can lead to loss of vision. The different animal models developed to mimic glaucomatous neurodegeneration, all result in RGC loss consequent optic nerve damage.
Methods: The present article summarizes experimental procedures and analytical methodologies related to one experimental model of glaucoma induced by optic nerve crush (ONC). Point-by-point protocol is reported with a particular focus on the critical point for the realization of the model. Moreover, information on the electroretinogram procedure and the immunohistochemical detection of RGCs are described to evaluate the morpho-functional consequences of ONC.
Discussion: Although the model of ONC is improperly assimilated to glaucoma, then the ONC model simulates most of the signaling responses consequent to RGC apoptosis as observed in models of experimental glaucoma. In this respect, the ONC model may be essential to elucidate the cellular and molecular mechanisms of glaucomatous diseases and may help to develop novel neuroprotective therapies.
Background and Objective: Subthreshold laser therapy has emerged as a therapeutic alternative to traditional laser photocoagulation for certain ophthalmic diseases including central serous chorioretinopathy (CSCR), diabetic macular edema (DME), macular edema secondary to branch retinal vein occlusion (BRVO), and age-related macular degeneration (AMD). The objective of this paper is to review and discuss the clinical applications of subthreshold laser and the mechanisms of different subthreshold laser techniques including subthreshold micropulse laser (SMPL), selective retina therapy (SRT), subthreshold nanosecond laser (SNL), endpoint management (EpM), and transpupillary thermotherapy (TTT).
Methods: A narrative review of English literature and publicly available information published before November 2021 from literature databases and computerized texts. We discuss the currently available subthreshold laser systems and the advancements made to perform different subthreshold laser techniques for various ophthalmic diseases. We highlight various clinical studies and therapeutic techniques that have been conducted to further understand the effectiveness of subthreshold laser in the clinical setting. We conclude the article by covering emerging subthreshold laser systems that are currently being developed for future clinical use. The PubMed database was utilized for peer-reviewed articles and pertinent information on subthreshold systems was cited from publicly available online websites covering specific systems.
Key Content and Findings: Various subthreshold laser systems have been developed to treat certain retinal diseases. Several systems are currently in development for future clinical applications.
Conclusions: While conventional laser photocoagulation has been effective in treating various retinal diseases, subthreshold laser systems aim to provide a therapeutic effect without visible signs of damage to the underlying tissue. This technology may be particularly effective in treating macular disorders. Further clinical studies are needed to evaluate their role in the management of retinal diseases.
Background and Objective: Subthreshold laser technologies and their applications in ophthalmology have greatly expanded in the past few decades. Initially used for retinal diseases such as central serous chorioretinopathy and diabetic macular edema, subthreshold lasers have recently shown efficacy in the treatment of various types of glaucoma. Our primary objectives are to review the clinical applications of subthreshold laser in the context of glaucoma treatment and discuss the mechanisms of different subthreshold laser techniques, including subthreshold selective laser trabeculoplasty (SSLT), micropulse laser trabeculoplasty (MLT), pattern-scanning laser trabeculoplasty (PSLT), titanium laser trabeculoplasty (TLT), and micropulse transscleral cyclophotocoagulation (MP-TSCPC).
Methods: This was a narrative review compiled from literature of PubMed and Google Scholar. The review was performed from March 2021 to October 2021 and included publications in English. We also included information from web pages to cover details of relevant laser systems. We discuss the history of subthreshold laser, recent advancements in subthreshold techniques, and commercially available systems that provide subthreshold capabilities for glaucoma. We highlight basic science and clinical studies that deepen the understanding of treatment mechanisms and treatment effectiveness in the clinical setting respectively. We review commonly used parameters for each technique and provide comparisons to conventional treatments.
Key Content and Findings: We found five distinct types of subthreshold laser used in the management of glaucoma. Numerous subthreshold laser systems are commercially available and can provide this treatment. Therefore, understanding the differences between subthreshold techniques and laser systems will be critical in utilizing subthreshold laser in the clinical setting.
Conclusions: Traditional laser trabeculoplasty (LT) and cyclophotocoagulation (CPC) have shown effectiveness in the treatment of various types of glaucoma but are associated with visible damage to the underlying tissue and adverse effects. Subthreshold laser systems aim to provide the therapeutic effect found in traditional lasers, while minimizing unwanted treatment related effects. Further clinical studies are needed to evaluate the role of subthreshold lasers in the management of glaucoma.
Background: To investigate the outcome of cataract surgery in patients with legal blindness defined as best-corrected visual acuity (BCVA) of 20/1,000 or lower and to determine factors influencing the visual outcome in these patients.
Methods: Medical records of 68 eyes of 62 patients diagnosed with legal blindness and underwent cataract surgery were reviewed. The study population was divided into 3 groups based on types of cataracts (Group A: posterior subcapsular cataract, Group B: mature or brunescent cataract, and Group C: cataract combined with other ocular diseases). Data including demographics, predisposing factors, BCVA before and 6 months after surgery and post-operative complications were collected and analyzed.
Results: Mean preoperative logMAR BCVA was 1.88±0.24, 2.24±0.26 and 1.96±0.31 in Groups A, B and C, respectively (P=0.003). The postoperative BCVA was 0.49±0.35, 0.51±0.47 and 0.90±0.53 in Groups A, B and C, respectively (p=0.003). Significant improvement in BCVA was shown in all 3 groups (P<0.001 in Groups A and B and, P=0.001 in Group C). There was significant difference in the amount of visual improvement among the 3 groups, P<0.001). Although there was no significant difference in the amount of visual improvement between group A and C (P=0.379), significantly higher visual improvement was achieved in group B compared with group A (P=0.012) and C (P=0.001).
Conclusions: Cataract surgery should be encouraged for patients with legal blindness, even in the presence of other ocular disease. Significant visual recovery was observed in all the groups, particularly in those with mature or brunescent cataract.
