Advanced Retina Implants

Interfacing with the Brain: How Nanotechnology Can Contribute

Interfacing artificial devices with the human brain is the central goal of neurotechnology. Yet, our imaginations are often limited by currently available paradigms and technologies. Suggestions for brain-machine interfaces have changed over time, along with the available technology. Mechanical levers and cable winches were used to move parts of the brain during the mechanical age. Sophisticated electronic wiring and remote control have arisen during the electronic age, ultimately leading to plug-and-play computer interfaces. Nonetheless, our brains are so complex that these visions, until recently, largely remained unreachable dreams. The general problem, thus far, is that most of our technology is mechanically and/or electrically engineered, whereas the brain is a living, dynamic entity. As a result, these worlds are difficult to interface with one another. Nanotechnology, which encompasses engineered solid-state objects and integrated circuits, excels at small length scales of single to a few hundred nanometers and, thus, matches the sizes of biomolecules, biomolecular assemblies, and parts of cells. Consequently, we envision nanomaterials and nanotools as opportunities to interface with the brain in alternative ways. Here, we review the existing literature on the use of nanotechnology in brain-machine interfaces and look forward in discussing perspectives and limitations based on the authors' expertise across a range of complementary disciplines─from neuroscience, engineering, physics, and chemistry to biology and medicine, computer science and mathematics, and social science and jurisprudence. We focus on nanotechnology but also include information from related fields when useful and complementary.

Exploring Molecular Pathways in Refractive Errors Associated with Inherited Retinal Dystrophies

The term inherited retinal dystrophies (IRDs) refers to a diverse range of conditions characterized by retinal dysfunction, and mostly deterioration, leading to a gradual decay of the visual function and eventually to total vision loss. IRDs have a global impact on about 1 in every 3000 to 4000 individuals. However, the prevalence statistics might differ significantly depending on the exact type of dystrophy and the demographic being examined. The cellular pathophysiology and genetic foundation of IRDs have been extensively studied, however, knowledge regarding associated refractive errors remain limited. This review aims to clarify the cellular and molecular processes that underlie refractive errors in IRDs. We did a thorough search of the current literature (Pubmed, accession Feb 2024), selecting works describing phenotypic differences among genes-related to IRDs, particularly in relation to refractive errors. First, we summarize the wide range of IRDs and their genetic causes, describing the genes and biological pathways connected to the etiology of the disease. We then explore the complex relationship between refractive errors and retinal dysfunction, including how the impairment of the vision-related mechanisms in the retina can affect ocular biometry and optical characteristics. New data about the involvement of aberrant signaling pathways, photoreceptor degeneration, and dysfunctional retinal pigment epithelium (RPE) in the development of refractive errors in IRDs have been examined. We also discuss the therapeutic implications of refractive defects in individuals with IRD, including possible approaches to treating visual impairments. In addition, we address the value of using cutting-edge imaging methods and animal models to examine refractive errors linked to IRDs and suggest future lines of inquiry for identifying new targets for treatment. In summary, this study presents an integrated understanding of the cellular and molecular mechanisms underlying refractive errors in IRDs. It illuminates the intricacies of ocular phenotypes in these conditions and offers a tool for understanding mechanisms underlying isolated refractive errors, besides the IRD-related forms.

An Eye on Extracellular Vesicles: Trends and Clinical Translations in Vision Research

Purpose

To perform a review of research, funding, and clinical translation efforts for extracellular vesicles (EVs) within vision science.

Design

Retrospective analysis of publication, funding, and clinical trials data.

Methods

A pretrained large language model (Jina2) was used to create semantic embeddings for 41 282 abstracts from articles related to EVs archived on EMBASE and published between January 1966 and January 2024. The articles were projected and clustered according to semantic embedding similarity, and research subdomains for EVs were determined through inspection of term frequency-inverse document frequency weighted word clouds. Mann-Kendall trend analysis was performed to identify current areas of growth within EV research. Additionally, National Institutes of Health funding data from RePORT Expenditures and Results and clinical trials data from ClinicalTrials.gov were analyzed to correlate publication trends with funding support and clinical translation efforts.

Results

Unsupervised clustering and Mann-Kendall trend analysis identified wound healing/regeneration (P = 0.030) and neurodegenerative disease (P = 0.049) as significantly accelerating in growth of publication over time. Ophthalmology-restricted subset analysis identified that publications in age-related macular degeneration (P = 0.191) and clinical applications (P = 0.086) are no longer growing at a significant rate. Analysis of funding data identified that the National Cancer Institute was the top funding institution overall, but that the National Institute on Aging is rapidly advancing in terms of funding EV research and trials. Analysis of ClinicalTrials.gov data highlights a dearth of clinical trials within ophthalmology despite a growing number of studies in other medical subfields.

Conclusions

Extracellular vesicles remain a promising substrate for both the identification and treatment of vision-threatening diseases. A better understanding of the current landscape of research and funding trends should help to inform future funding and translational efforts.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Short-Term Results of Multiwavelength Photobiomodulation in Retinitis Pigmentosa

Objective

To assess the short-term effects of Multiwavelength Photobiomodulation (LumiThera Valeda Light Delivery System) on retinal functional behavior in patients with retinitis pigmentosa (RP).

Materials and Methods

Twelve RP patients (24 eyes) underwent treatment involving nine photobiomodulation (PBM) sessions using the Valeda system, which emits three distinct wavelengths within the yellow (590 nm; 4 mW/cm2), red (660 nm; 65 mW/cm2), and near-infrared (NIR) (850 nm; 0.6 mW/cm2) spectrum. All evaluations were conducted four weeks post-therapy. The treated eye was compared with baseline (pre-therapy). Following nine PBM sessions, assessments included best-corrected visual acuity (BCVA), retinal sensitivity, and characteristics of the correction area via fundus automated perimetry using the Compass system. Additionally, a functional and structural assessment of the retina was performed using multifocal electroretinography (ERG), optical coherence tomography (OCT), fluorescence retinography (FR), and autofluorescence (AF). Statistical analysis employed the Student's t-test for paired samples at a 95% confidence level (p-value ≤ 0.05).

Results

LogMAR-based visual acuity assessment demonstrated an improvement in mean value from 0.62 to 0.53 logMAR, with a statistically significant p-value of 0.001. Visual field examination, based on mean deviation (MD), pattern standard deviation (PSD), and fundal perimeter deviation index (FPDI) parameters, showed improvement from -19.87 dB to -19.45 dB, 9.77 dB to 9.76 dB, and 37% to 39%, respectively, although with non-significant p-values of 0.366, 0.446, and 0.245, respectively. No adverse effects or abnormalities in optical coherence tomography (OCT) and electroretinogram (ERG) were observed during the follow-up period.

Conclusion

In this short-term study, PBM appeared to have the potential to enhance BCVA and fundus automated perimeter in RP patients without causing significant adverse events. However, further assessment with a larger patient cohort and longer follow-up is warranted to ascertain the efficacy of this technique in these patients.

Recent Advancements in Bioelectronic Medicine: A Review

Bioelectronic medicine is a multidisciplinary field that combines molecular medicine, neurology, engineering, and computer science to design devices for diagnosing and treating diseases. The advancements in bioelectronic medicine can improve the precision and personalization of illness treatment. Bioelectronic medicine can produce, suppress, and measure electrical activity in excitable tissue. Bioelectronic devices modify specific neural circuits using electrons rather than pharmaceuticals and uses of bioelectronic processes to regulate the biological processes underlining various diseases. This promotes the potential to address the underlying causes of illnesses, reduce adverse effects, and lower costs compared to conventional medication. The current review presents different important aspects of bioelectronic medicines with recent advancements. The area of bioelectronic medicine has a lot of potential for treating diseases, enabling non-invasive therapeutic intervention by regulating brain impulses. Bioelectronic medicine uses electricity to control biological processes, treat illnesses, or regain lost capability. These new classes of medicines are designed by the technological developments in the detection and regulation of electrical signaling methods in the nervous system. Peripheral nervous system regulates a wide range of processes in chronic diseases; it involves implanting small devices onto specific peripheral nerves, which read and regulate the brain signaling patterns to achieve therapeutic effects specific to the signal capacity of a particular organ. The potential for bioelectronic medicine field is vast, as it investigates for treatment of various diseases, including rheumatoid arthritis, diabetes, hypertension, paralysis, chronic illnesses, blindness, etc.

Randomized Phase 2b Study of Brimonidine Drug Delivery System Generation 2 for Geographic Atrophy in Age-related Macular Degeneration

PURPOSE

To evaluate the safety and efficacy of repeat injections of Brimonidine Drug Delivery System (Brimo DDS) Generation 2 (Gen 2) containing 400 μg brimonidine in patients with geographic atrophy (GA) secondary to age-related macular degeneration (AMD).

DESIGN

Phase 2b, randomized, multicenter, double-masked, sham-controlled, 30-month study (BEACON).

PARTICIPANTS

Patients diagnosed with GA secondary to AMD and multifocal lesions with total area >1.25 mm² and ≤18 mm² in the study eye.

METHODS

Enrolled patients were randomized to treatment with intravitreal injections of 400-μg Brimo DDS (n=154) or sham procedure (n=156) in the study eye every 3 months from day 1 through month 21.

MAIN OUTCOME MEASURES

The primary efficacy endpoint was change from baseline in the GA lesion area in the study eye, assessed with fundus autofluorescence imaging, at month 24. Safety measures included treatment-emergent adverse events (AEs).

RESULTS

The study was terminated early, at the time of the planned interim analysis, because of a slow GA progression rate (∼1.6 mm²/year) in the enrolled population. Least-squares mean (standard error) GA area change from baseline at month 24 (primary endpoint) was 3.24 (0.13) mm² with Brimo DDS (n=84) versus 3.48 (0.13) mm² with sham (n=91); the reduction in GA area change from baseline in the Brimo DDS group compared with the sham group was 0.25 mm² (7%) (P = 0.150). At month 30, the GA area change from baseline was 4.09 (0.15) mm² with Brimo DDS (n=49) versus 4.52 (0.15) mm² with sham (n=46), a reduction of 0.43 mm² (10%) with Brimo DDS compared with sham (P=0.033). Exploratory analysis showed numerically smaller loss over time in retinal sensitivity assessed with scotopic microperimetry with Brimo DDS compared with sham (P=0.053 at month 24). Treatment-related AEs were usually related to the injection procedure. No implant accumulation was observed.

CONCLUSIONS

Multiple intravitreal administrations of Brimo DDS (Gen 2) were well tolerated. The primary efficacy endpoint at 24 months was not met, but there was a numerical trend for reduction in GA progression at 24 months compared with sham treatment. The study was terminated early because of the lower-than-expected GA progression rate in the sham/control group.