Clinical Research on the Leading Causes of Severe Sight Impairment in the UK General and Working Populations

Purpose: Clinical research brings the potential of improved diagnostics, sight-saving treatments, and more accessible services to those suffering with severe sight impairment (SSI). This report investigates whether registered ophthalmology clinical studies address the leading causes of SSI in the general and working populations of the United Kingdom (UK).Methods: The latest statistics on the leading causes of SSI in the UK general and working populations were identified by searching PubMed, Cochrane Library, and TRIP databases. Clinical study registries were searched to identify registered clinical studies (on or prior to 1st December 2022) on the leading causes of SSI. The relationship between the number of clinical studies on leading causes of SSI and the percentage of SSI certifications they account for was analyzed.Results: In the UK general population, the number of registered clinical studies on the leading causes of SSI is statistically significantly correlated (Spearman’s rho = 0.86, p Conclusion: Clinical research into the leading causes of SSI in the general population is essential. However, it is important to consider eye conditions that cause the most severe visual impairment in individuals of working age due to the significant health and socioeconomic implications of sight loss in this population.</p

Masking response in <i>Opa1^+/+</i> and <i>Opa1^+/−</i> mice.

<p>(A) The average wheel running revolutions on the night (gray background) of the 3 h light pulse (white background) are plotted relative to the baseline levels (the night before the pulse) for <i>Opa1^+/+</i> (n = 6) and <i>Opa1^+/−</i> (n = 7) mice. The masking pulse completely suppressed activity in both genotypes immediately. ANOVA analysis found no significant effect of genotype on the baseline corrected activity levels (p = 0.468) (B) Hourly breakdown of activity during the masking pulse. A 2-way ANOVA using activity in each hour of light pulse and genotype as factors found a significant effect of hour of light pulse (p<0.005) but no significant effect of genotype (p = 0.143) and no interaction between genotype and light pulse hour (p = 0.359). All data are presented as mean ± SEM.</p

Phase shift behaviour in <i>Opa1^+/+</i> and <i>Opa1^+/−</i> mice.

<p>Representative actograms from (A) <i>Opa1</i>^+/+ and (B) <i>Opa1</i>^+/<i>−</i> mice in constant dark (DD) conditions. Animals were exposed to 15 min light pulses every ∼15 days. Photon matched pulses at 480 nm (black arrow) or 525 nm (white arrow; 1×10¹¹ photons/s/cm²) were applied at CT16. Animals were also exposed to a dark sham pulse condition (grey arrow). (C) The size of the phase shift response are plotted for the 525 nm, 480 nm and sham conditions for <i>Opa1^+/+</i> (n = 6) and <i>Opa1^+/−</i> (n = 7) mice. A two-way ANOVA with genotype and wavelength as factors was performed. There was no significant effect of wavelength (<i>p</i> = 0.66) or genotype (<i>p</i> = 0.17) and the interaction of genotype and wavelength was not significant (<i>p</i> = 0.91).</p

Circadian behaviour in <i>Opa1^+/+</i> and <i>Opa1^+/−</i> mice.

<p>Representative actograms from (A) <i>Opa1 </i>^+/+ and (B) <i>Opa1 </i>^+/− mice entrained to a 12/12 LD cycle and subsequently released into constant darkness (DD). Each horizontal line corresponds to one day and the data has been double plotted. The black vertical bars represent activity (i.e. wheel revolutions). The shaded region represents lights ON. (C) Table showing average period (τ), total activity levels and length of the active phase in LD and in DD for <i>Opa1^+/+</i> (n = 6) and <i>Opa1^+/−</i> (n = 7) mice. There were no significant differences between genotypes (unpaired students t-test; p values are shown). All data are presented as mean ± SEM.</p

Pupil light reflex in <i>Opa1^+/+</i> and <i>Opa1^+/−</i> mice.

<p>The average minimum pupil area expressed as a percentage of maximum dilation following illumination with various intensities of white light for <i>Opa1^+/+</i> (n = 5) and <i>Opa1^+/−</i> (n = 5) mice. All data are fitted with four term sigmoidal functions (solid lines) of the form y = y0+a/(1+exp(-(x-x0)/b)) (goodness of fit of fitted curve to actual data (R2): <i>Opa1^+/+</i> = 0.993 and <i>Opa1^+/−</i> = 0.995). A 2-way ANOVA using intensity and genotype as factors showed a significant effect of light intensity (p<0.0001) but no significant effect of genotype (p = 0.51) and no significant interaction between genotype and intensity (p = 0.99).</p

Melanopsin expression in <i>Opa1^+/+</i> and <i>Opa1^+/−</i> retinae.

<p>Overall distribution of melanopsin-positive RGCs in a flatmount retina from (A) <i>Opa1</i>^+/+ and (B) <i>Opa1</i>^+/<i>−</i> mice. The total number of melanopsin expressing cells was not significantly different between genotypes (<i>Opa1^+/+</i>: n = 3; <i>Opa1^+/</i>: n = 3). (C) Quantification of melanopsin (<i>Opn4</i>) and <i>Opa1</i> gene expression by real time quantitative PCR. Expression levels in <i>Opa1^+/−</i> animals are plotted relative to wildtype data. No significant difference in expression was detected for <i>Opn4</i> between genotypes. A significant reduction in <i>Opa1</i> expression was observed in <i>Opa1^+/−</i> mice relative to wildtype controls (student's t-test. * = p<0.005). (D) Representative confocal images of melanopsin cells in <i>Opa1^+/+</i> and <i>Opa1^+/−</i> retinae. A projected image of a confocal stack (from the inner plexiform layer to the ganglion cell layer) is shown for each genotype. An image at the plane of the outermost region of sublamina a and an image at the plane of the innermost region of sublamina b from the same image stacks is also shown.</p

Analysis of Green fluorescent protein (GFP) fluorescence intensity measurement of SH-SY5Y cells <i>in vitro</i> 9 days after transfection using different recombinant AAV serotypes.

<p>Representative images are shown of GFP fluorescence following transduction with rAAV2/2, rAAV2/5, rAAV2/Rec2 and rAAV2/Rec3 (A). Analysis of grey value (B) and percentage of pixels above threshold (C) are shown in the bottom row, demonstrating significant differences between standard rAAV2/2 and rAAV2/5 serotypes and hybrid recombinant vectors (*p&lt;0.05, **p&lt;0.01, ***p&lt;0.001). In order to ensure levels of cell confluence did not differ between groups and affect transduction, Hoechst-labeled nuclei were counted in each field analyzed, with no significant difference between groups (D). Scale bar 50 µm.</p

Quantitative analysis of green fluorescent protein (GFP) fluorescence intensity on histological sections in eyes that underwent subretinal injection of different recombinant AAV serotypes expressing GFP (mean±SEM).

<p>Two mouse models for retinal degeneration (<i>Abca4^−/−</i> and <i>Pde6b^rd1/rd1</i> mice) are compared with wild type (WT) mice. Grey level analysis (upper row) represented an estimate for the level of transgene expression within transduced cells, whereas the percentage (%) of pixels above threshold (bottom row) represented an estimate of viral efficacy for cell transduction. 4 to 8 eyes were analysed per group. ONL = outer nuclear layer, RPE = retinal pigment epithelium.</p

Green fluorescent protein (GFP) fluorescence patterns of different recombinant AAV serotypes in the degenerate retina of <i>Pde6b^rd1/rd1</i> mice following subretinal injection.

<p>The main images a–d are confocal stacks illustrating overall GFP expression patterns. For each serotype, images i–iii are confocal slices showing GFP expression (green), nuclear labeling (blue) and immunostaining with calbindin identifying horizontal cells (red). Colocalisation of signals indicates horizontal cell transduction. Images iv–vi show colocalisation of GFP (green) in ganglion cells identified by Brn-3a immunostaining (red) demonstrating ganglion cell transduction. GCL = ganglion cell layer, INL = inner nuclear layer, RPE = retinal pigment epithelium. Scale bar: 30 µm for images a–d, 10 µm for images i–vi.</p

Green fluorescent protein (GFP) fluorescence following <i>ex vivo</i> administration of hybrid recombinant AAV vectors.

<p>GFP expression in macaque explants following rAAV2/Rec2 transduction (A) and histology of cross-sectional specimens showing expression of GFP (green) in the ganglion cell layer (B,C). Image D shows GFP expression in macaque explants following rAAV2/Rec3 transduction. GCL = ganglion cell layer; INL = inner nuclear layer.</p