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.
Background: The complexity of the glaucoma pathophysiology is directly reflected on its experimental modeling for studies about pathological mechanisms and treatment approaches. Currently, a variety of in vivo models are available for the study of glaucoma, although they do not reach an exact reproduction of all aspects characterizing the human glaucoma. Therefore, a comprehensive view of disease onset, progression and treatment efficacy can only be obtained by the integration of outcomes deriving from different experimental models.
Methods: The present article summary experimental procedures and analytical methodologies related with two experimental models of glaucoma belonging to the classes of induced intraocular pressure (IOP)-elevation and genetic models, methyl cellulose (MCE)-induced ocular hypertension and DBA/2J mouse strain. Point-by-point protocols are reported with a particular focus on the critical point for the realization of each model. Moreover, typical strength and drawbacks of each model are described in order to critically handle the outcomes deriving from each model.
Discussion: This paper provides a guideline for the realization, analysis and expected outcomes of two models allowing to study IOP-driven neurodegenerative mechanisms rather than IOP-independent neurodegeneration. The complementary information from these models could enhance the analysis of glaucomatous phenomena from different points of view potentiating the basic and translational study of glaucoma.
