To evaluate acquired color vision deficiency in glaucoma by using the Rabin cone contrast test (RCCT).
Twenty-seven eyes of 27 patients with glaucoma (glaucoma group) and 27 eyes of 27 normal ...subjects (control group) were included in this study. Long (L), medium (M), and short (S) CCT scores (L CCTs, M CCTs, and S CCTs, respectively) were measured using the RCCT in both groups. Visual field examinations were performed with Humphrey automated perimetry using the Swedish interactive thresholding algorithm 30-2, and the mean deviation (MD) was evaluated. The macular ganglion cell/inner plexiform layer (GCIPL) thickness was measured using high-definition optical coherence tomography in the glaucoma group.
The mean M CCTs and S CCTs in the glaucoma group were significantly lower (P<0.05 for both comparisons) than in the control group (M CCTs, 80.7±16.8 vs. 91.9±8.22; S CCTs, 83.9±19.5 vs. 97.4±3.77, respectively); the L CCTs did not differ significantly (P=0.065) from those of the controls (91.8±12.8 vs. 97.4±3.50, respectively). The M CCTs and S CCTs were correlated significantly with those of MD (M CCTs, r=0.47; S CCTs, r=0.44; P<0.05 for both comparisons) and GCIPL thickness (M CCTs, r=0.70; P<0.0001; S CCTs, r=0.57; P<0.01).
The chromatic discrimination thresholds measured by RCCT in the glaucoma group were significantly different from those measured in the control group and were correlated with the MD and GCIPL thickness. The RCCT may be useful for evaluating acquired color vision deficiency in glaucoma and may help advance current understanding of the pathophysiology of glaucomatous damage.
Achromatopsia (ACHM) is a congenital, autosomal recessive retinal disease that manifests cone dysfunction, reduced visual acuity and color vision, nystagmus, and photoaversion. Five genes are known ...causes of ACHM. The present study took steps toward performing a trial of gene therapy in ACHM by characterizing the genetics of ACHM in Israel and the Palestinian Territories and analyzing retinal function and structure in CNGA3 ACHM patients from the Israeli-Palestinian population and US patients with other origins.
Case series study.
Patients with clinically suspected ACHM, cone dysfunction phenotypes, and unaffected family members were included. The protocol was approved by the local institutional review board and informed consent was obtained from all participants.
Genetic analyses included homozygosity mapping and exome sequencing. Phenotype was assessed with electroretinography (ERG), optical coherence tomography, psychophysics, and photoaversion testing.
Single nucleotide polymorphism microarray, exome analysis, DNA sequence analysis, visual function testing including ERG, and photoaversion.
We identified 148 ACHM patients from 57 Israeli and Palestinian families; there were 16 CNGA3 mutations (5 novel) in 41 families and 5 CNGB3 mutations (1 novel) in 8 families. Two CNGA3 founder mutations underlie >50% of cases. These mutations lead to a high ACHM prevalence of ∼1:5000 among Arab-Muslims residing in Jerusalem. Rod ERG abnormalities (in addition to cone dysfunction) were detected in 59% of patients. Retinal structure in CNGA3 ACHM patients revealed persistent but abnormal foveal cones. Under dark- and light-adapted conditions, patients use rod-mediated pathways. Photoaversion was readily demonstrated with transition from the dark to a dim light background.
Among Israeli and Palestinian patients, CNGA3 mutations are the leading cause of ACHM. Retinal structural results support the candidacy of CNGA3 ACHM for clinical trials for therapy of cone photoreceptors. Efficacy outcome measures would include chromatic light-adapted psychophysics, with attention to the photoreceptor basis of the response, and quantitation of photoaversion.
The CNGA3(-/-)/Nrl(-/-) mouse is a cone-dominant model with Cnga3 channel deficiency, which partially mimics the all cone foveal structure of human achromatopsia 2 with CNGA3 mutations. Although ...subretinal (SR) AAV vector administration can transfect retinal cells efficiently, the injection-induced retinal detachment can cause retinal damage, particularly when SR vector bleb includes the fovea. We therefore explored whether cone function-structure could be rescued in CNGA3(-/-)/Nrl(-/-) mice by intravitreal (IVit) delivery of tyrosine to phenylalanine (Y-F) capsid mutant AAV8. We find that AAV-mediated CNGA3 expression can restore cone function and rescue structure following IVit delivery of AAV8 (Y447, 733F) vector. Rescue was assessed by restoration of the cone-mediated electroretinogram (ERG), optomotor responses, and cone opsin immunohistochemistry. Demonstration of gene therapy in a cone-dominant mouse model by IVit delivery provides a potential alternative vector delivery mode for safely transducing foveal cones in achromatopsia patients and in other human retinal diseases affecting foveal function.
Hue and luminance contrast are basic visual features. Here we use multivariate analyses of magnetoencephalography data to investigate the timing of the neural computations that extract them, and ...whether they depend on common neural circuits. We show that hue and luminance-contrast polarity can be decoded from MEG data and, with lower accuracy, both features can be decoded across changes in the other feature. These results are consistent with the existence of both common and separable neural mechanisms. The decoding time course is earlier and more temporally precise for luminance polarity than hue, a result that does not depend on task, suggesting that luminance contrast is an updating signal that separates visual events. Meanwhile, cross-temporal generalization is slightly greater for representations of hue compared to luminance polarity, providing a neural correlate of the preeminence of hue in perceptual grouping and memory. Finally, decoding of luminance polarity varies depending on the hues used to obtain training and testing data. The pattern of results is consistent with observations that luminance contrast is mediated by both L-M and S cone sub-cortical mechanisms.
Mutations in the CNGB3 gene account for >50% of all known cases of achromatopsia. Although of early onset, its stationary character and the potential for rapid assessment of restoration of retinal ...function following therapy renders achromatopsia a very attractive candidate for gene therapy. Here we tested the efficacy of an rAAV2/8 vector containing a human cone arrestin promoter and a human CNGB3 cDNA in CNGB3 deficient mice. Following subretinal delivery of the vector, CNGB3 was detected in both M- and S-cones and resulted in increased levels of CNGA3, increased cone density and survival, improved cone outer segment structure and normal subcellular compartmentalization of cone opsins. Therapy also resulted in long-term improvement of retinal function, with restoration of cone ERG amplitudes of up to 90% of wild-type and a significant improvement in visual acuity. Remarkably, successful restoration of cone function was observed even when treatment was initiated at 6 months of age; however, restoration of normal visual acuity was only possible in younger animals (e.g. 2-4 weeks old). This study represents achievement of the most substantial restoration of visual function reported to date in an animal model of achromatopsia using a human gene construct, which has the potential to be utilized in clinical trials.
Blue cone monochromacy (BCM) is an X-linked congenital vision disorder characterized by complete loss or severely reduced L- and M-cone function. Patients with BCM display poor visual acuity, ...severely impaired color discrimination, myopia, nystagmus, and minimally detectable cone-mediated electroretinogram. Recent studies of patients with BCM with adaptive optics scanning laser ophthalmoscopy (AOSLO) showed that they have a disrupted cone mosaic with reduced numbers of cones in the fovea that is normally dominated by L- and M-cones. The remaining cones in the fovea have significantly shortened outer segments but retain sufficient structural integrity to serve as potential gene therapy targets. In this study, we tested whether exogenously expressed human L- and M-opsins can rescue M-cone function in an M-opsin knockout (
) mouse model for BCM.
Adeno-associated virus type 5 (AAV5) vectors expressing OPN1LW, OPN1MW, or C-terminal tagged OPN1LW-Myc, or OPN1MW-HA driven by a cone-specific promoter were injected subretinally into one eye of
mice, while the contralateral eye served as the uninjected control. Expression of cone pigments was determined with western blotting and their cellular localization identified with immunohistochemistry. M-cone function was analyzed with electroretinogram (ERG). Antibodies against cone phototransduction proteins were used to study cone outer segment (OS) morphology in untreated and treated
eyes.
We showed that cones in the dorsal retina of the
mouse do not form outer segments, resembling cones that lack outer segments in the human BCM fovea. We further showed that AAV5-mediated expression of either human M- or L-opsin individually or combined promotes regrowth of cone outer segments and rescues M-cone function in the treated
dorsal retina.
Exogenously expressed human opsins can regenerate cone outer segments and rescue M-cone function in
mice, thus providing a proof-of-concept gene therapy in an animal model of BCM.
To examine the foveal avascular zone (FAZ) in patients with congenital achromatopsia (ACHM).
Forty-two patients with genetically confirmed ACHM were imaged either with Optovue's AngioVue system or ...Zeiss's Plex Elite 9000, and the presence or absence of a FAZ was determined. For images where a FAZ was present and could be confidently segmented, FAZ area, circularity index, and roundness were measured and compared with previously published normative values. Structural optical coherence tomography images were acquired to assess the degree of foveal hypoplasia (number and thickness of inner retinal layers present at the fovea).
A FAZ was present in 31 of 42 patients imaged (74%), although no determination could be made for 11 patients due to poor image quality (26%). The mean ± SD FAZ area for the ACHM retina was 0.281 ± 0.112 mm2, which was not significantly different from the previously published normative values (P = 0.94). However, their FAZs had decreased circularity (P < 0.0001) and decreased roundness (P < 0.0001) compared to the normative cohort. In the patients with ACHM examined here, the FAZ area decreased as the number and thickness of the retained inner retinal layers increased.
Our data demonstrate that despite the presence of foveal hypoplasia, patients with ACHM can have a FAZ. This is distinct from other conditions associated with foveal hypoplasia, which generally show an absence of the FAZ. In ACHM, FAZ formation does not appear to be sufficient for complete pit formation, contrary to some models of foveal development.
Cone/cone-rod dystrophy is a large group of retinal disorders with both phonotypic and genetic heterogeneity. The purpose of this study was to characterize the phenotype of eight patients from seven ...families harboring POC1B mutations in a cohort of the Japan Eye Genetics Consortium (JEGC).
Whole-exome sequencing with targeted analyses identified homozygous or compound heterozygous mutations of the POC1B gene in 7 of 548 families in the JEGC database. Ophthalmologic examinations including the best-corrected visual acuity, perimetry, fundus photography, fundus autofluorescence imaging, optical coherence tomography, and full-field and multifocal electroretinography (ERGs) were performed.
There were four men and four women whose median age at the onset of symptoms was 15.6 years (range, 6-23 years) and that at the time of examination was 40.3 years (range, 22-67 years). The best-corrected visual acuity ranged from -0.08 to 1.52 logMAR units. The funduscopic appearance was normal in all the cases except in one case with faint mottling in the fovea. Optical coherence tomography revealed an absence of the interdigitation zone and blurred ellipsoid zone in the posterior pole, but the foveal structures were preserved in three cases. The full-field photopic ERGs were reduced or extinguished with normal scotopic responses. The central responses of the multifocal ERGs were preserved in two cases. The diagnosis was either generalized cone dystrophy in five cases or cone dystrophy with foveal sparing in three cases.
Generalized or peripheral cone dystrophy with normal funduscopic appearance is the representative phenotype of POC1B-associated retinopathy in our cohort.
Congenital achromatopsia is an autosomal recessive disease causing substantial reduction or complete absence of cone function. Although believed to be a relatively stationary disorder, questions ...remain regarding the stability of cone structure over time. In this study, the authors sought to assess the repeatability of and examine longitudinal changes in measurements of central cone structure in patients with achromatopsia.
Forty-one subjects with CNGB3-associated achromatopsia were imaged over a period of between 6 and 26 months using optical coherence tomography and adaptive optics scanning light ophthalmoscopy. Outer nuclear layer (ONL) thickness, ellipsoid zone (EZ) disruption, and peak foveal cone density were assessed.
ONL thickness increased slightly compared with baseline (0.184 μm/month, P = 0.02). The EZ grade remained unchanged for 34/41 subjects. Peak foveal cone density did not significantly change over time (mean change 1% per 6 months, P = 0.126).
Foveal cone structure showed little or no change in this group of subjects with CNGB3-associated achromatopsia. Over the time scales investigated (6-26 months), achromatopsia seems to be a structurally stable condition, although longer-term follow-up is needed. These data will be useful in assessing foveal cone structure after therapeutic intervention.
Previously we showed that AAV5-mediated expression of either human M- or L-opsin promoted regrowth of cone outer segments and rescued M-cone function in the treated M-opsin knockout (Opn1mw-/-) ...dorsal retina. In this study, we determined cone viability and window of treatability in aged Opn1mw-/- mice.
Cone viability was assessed with antibody against cone arrestin and peanut agglutinin (PNA) staining. The rate of cone degeneration in Opn1mw-/- mice was quantified by PNA staining. AAV5 vector expressing human L-opsin was injected subretinally into one eye of Opn1mw-/- mice at 1, 7, and 15 months old, while the contralateral eyes served as controls. M-cone-mediated retinal function was analyzed 2 and 13 months postinjection by full-field ERG. L-opsin transgene expression and cone outer segment structure were examined by immunohistochemistry.
We showed that dorsal M-opsin dominant cones exhibit outer segment degeneration at an early age in Opn1mw-/- mice, whereas ventral S-opsin dominant cones were normal. The remaining M-opsin dominant cones remained viable for at least 15 months, albeit having shortened or no outer segments. We also showed that AAV5-mediated expression of human L-opsin was still able to rescue function and outer segment structure in the remaining M-opsin dominant cones when treatment was initiated at 15 months of age.
Our results showing that the remaining M-opsin dominant cones in aged Opn1mw-/- mice can still be rescued by gene therapy is helpful for establishing the window of treatability in future blue cone monochromacy clinical trials.
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