Purpose
To analyze mitochondrial DNA (mt DNA) gene mutations in a 19-year-old female patient, who presented with chronic progressive external ophthalmoplegia (CPEO), together with her mother and younger sister.
Methods
The diagnosis of mitochondrial myopathy was made based on clinical and biologic analysis. Histochemical methods were used to detect ragged-red fibers (RRFs) and ragged-blue fibers (RBFs) on a muscle biopsy of the patient. All mitochondrial gene DNA fragments of the patient, her mother, and younger sister were amplified by polymerase chain reaction. The products were sequenced and compared with reference databases.
Results
A novel T1658C mutation and a known A10006G mutation were identified in the mitochondrial tRNAVal gene and the tRNAGly gene, respectively, in the patient, her mother, and younger sister. The T1658C mutation changes the T loop structure of mitochondrial tRNAVal and the A10006G mutation disturbs the D loop of mitochondrial tRNAGly.
Conclusions
The T1658C and A10006G mutations of mtDNA may be responsible for the pathogenesis of the patient with CPEO.
Aims: to evaluate the performance of the RETeval device, a handheld instrument using flicker electroretinography (ERG) and pupillography on undilated subjects with diabetes, to detect vision-threatening diabetic retinopathy (VTDR). Methods: performance was measured using a cross-sectional, single armed, non-interventional, multi-site study with Early Treatment Diabetic Retinopathy Study 7-standard field, stereo, color fundus photography as the gold standard. The 468 subjects were randomized to a calibration phase (80%), whose ERG and pupillary waveforms were used to formulate an equation correlating with the presence of VTDR, and a validation phase (20%), used to independently validate that equation. The primary outcome was the prevalence-corrected area under the receiver operating characteristic (ROC) curve for the detection of VTDR. Results: the area under the ROC curve was 0.86 for VTDR. With a sensitivity of 83%, the specificity was 78% and the negative predictive value was 99%. The average testing time was 2.3 min. Conclusions: with a VTDR prevalence similar to that in the US, the RETeval device will identify about 75% of the population as not having VTDR with 99% accuracy. The device is simple to use, does not require pupil dilation, and has a short testing time.
PURPOSE. MicroRNA (miRNAs) have been previously implicated in scleral remodeling in normal eye growth. They have the potential to be therapeutic targets for prevention/ retardation of exaggerated eye growth in myopia by modulating scleral matrix remodeling. To explore this potential, genome-wide miRNA and messenger RNA (mRNA) scleral profiles in myopic and control eyes from mice were studied. METHODS. C57BL/6J mice (n = 7; P28) reared under a 12L:12D cycle were form-deprived (FD) unilaterally for 2 weeks. Refractive error and axial length changes were measured using photorefraction and 1310-nm spectral-domain optical coherence tomography, respectively. Scleral RNA samples from FD and fellow control eyes were processed for microarray assay. Statistical analyses were performed using National Institute of Aging array analysis tool; group comparisons were made using ANOVA, and gene ontologies were identified using software available on the Web. Findings were confirmed using quantitative PCR in a separate group of mice (n = 7). RESULTS. Form-deprived eyes showed myopic shifts in refractive error (–2.02 ± 0.47 D; P < 0.01). Comparison of the scleral RNA profiles of test eyes with those of control eyes revealed 54 differentially expressed miRNAs and 261 mRNAs fold-change >1.25 (maximum fold change = 1.63 and 2.7 for miRNAs and mRNAs, respectively) (P < 0.05; minimum, P = 0.0001). Significant ontologies showing gene over-representation (P < 0.05) included intermediate filament organization, scaffold protein binding, detection of stimuli, calcium ion, G protein, and phototransduction. Significant differential expression of Let-7a and miR-16-2, and Smok4a, Prph2, and Gnat1 were confirmed. CONCLUSIONS. Scleral mi- and mRNAs showed differential expression linked to myopia, supporting the involvement of miRNAs in eye growth regulation. The observed general trend of relatively small fold-changes suggests a tightly controlled, regulatory mechanism for scleral gene expression.
by
Shanu Markand;
Natecia L. Baskin;
Ranjay Chakraborty;
Erica Landis;
Sara A. Wetzstein;
Kevin J. Donaldson;
Priyanka Priyadarshani;
Shannon E. Alderson;
Curran S. Sidhu;
Jeffrey Boatright;
Paul Iuvone;
Machelle Pardue;
John Nickerson
PURPOSE: Interphotoreceptor retinoid-binding protein (IRBP) is abundant in the subretinal space and binds retinoids and lipophilic molecules. The expression of IRBP begins precociously early in mouse eye development. IRBP-deficient (KO) mice show less cell death in the inner retinal layers of the retina before eyelid opening compared to wild-type C57BL/6J (WT) controls and eventually develop profound myopia. Thus, IRBP may play a role in eye development before visually-driven phenomena. We report comparative observations during the course of the natural development of eyes in WT and congenic IRBP KO mice that suggest IRBP is necessary at the early stages of mouse eye development for correct function and development to exist in later stages. METHODS: We observed the natural development of congenic WT and IRBP KO mice, monitoring several markers of eye size and development, including haze and clarity of optical components in the eye, eye size, axial length, immunohistological markers of differentiation and eye development, visually guided behavior, and levels of a putative eye growth stop signal, dopamine. We conducted these measurements at several ages. Slit-lamp examinations were conducted at post-natal day (P)21. Fundus and spectral domain optical coherence tomography (SD-OCT) images were compared at P15, P30, P45, and P80. Enucleated eyes from P5 to P10 were measured for weight, and ocular dimensions were measured with a noncontact light-emitting diode (LED) micrometer. We counted the cells that expressed tyrosine hydroxylase (TH-positive cells) at P23-P36 using immunohistochemistry on retinal flatmounts. High-performance liquid chromatography (HPLC) was used to analyze the amounts of dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) at P7-P60. Monocular form deprivation in the right eye was induced using head-mounted goggles from P28 to P56. RESULTS: Eye elongation and eye size in the IRBP KO mice began to increase at P7 compared to the WT mice. This difference increased until P12, and the difference was maintained thereafter. SD-OCT images in live mice confirmed previously reported retinal thinning of the outer nuclear layer in the IRBP KO mice compared to the WT mice from P15 to P80. Slit-lamp and fundoscopy examination outcomes did not differ between the WT and KO mice. SD-OCT measurements of the optical axis components showed that the only factor contributing to excess optical axis length was the depth of the vitreous body. No other component of optical axis length (including corneal thickness, anterior chamber depth, and lens thickness) was different from that of the WT mouse. The refractive power of the IRBP KO mice did not change in response to form deprivation. The number of retinal TH-positive cells was 28% greater in the IRBP KO retinas compared to the WT mice at P30. No significant differences were observed in the steady-state retinal DA or DOPAC levels or in the DOPAC/DA ratios between the WT and IRBP KO mice. CONCLUSIONS: The IRBP KO mouse eye underwent precocious development and rapid eye size growth temporally about a day sooner than the WT mouse eye. Eye size began to differ between the WT and KO mice before eyelid opening, indicating no requirement for focus-dependent vision, and suggesting a developmental abnormality in the IRBP KO mouse eye that precedes form vision-dependent emmetropization. Additionally, the profoundly myopic KO eye did not respond to form deprivation compared to the non-deprived contralateral eye. Too much growth occurred in some parts of the eye, possibly upsetting a balance among size, differentiation, and focus-dependent growth suppression. Thus, the loss of IRBP may simply cause growth that is too rapid, possibly due to a lack of sequestration or buffering of morphogens that normally would bind to IRBP but are unbound in the IRBP KO eye. Despite the development of profound myopia, the DA levels in the IRBP KO mice were not statistically different from those in the WT mice, even with the excess of TH-positive cells in the IRBP KO mice compared to the WT mice. Overall, these data suggest that abnormal eye elongation in the IRBP KO mouse is independent of, precedes, and is epistatic to the process(es) of visually-driven refractive development.
Purpose: To provide perspective on the implications of the Comparison of Age-Related Macular Degeneration Treatments Trials (CATT) on intravitreal biologic agents in uveitis and retinal diseases in which ocular inflammatory pathways are central to their pathogenesis. Design: Interpretative essay. Methods: Literature review and interpretation. Results: Besides the clear importance of CATT from a patient treatment perspective in age-related macular degeneration (AMD), these data highlight the critical relevance of highly specific protein immunotherapies offered with biologic agents. The CATT trial also provides a reminder regarding the importance of rigorous efficacy and safety monitoring required when administering intravitreal biologic therapy. Within the field of uveitis, systemic and local biologics have been used to effectively treat uveitis, targeting pathways implicated in both angiogenesis and inflammation (eg, tumor necrosis factor-α [TNF-α] and interleukin-2 pathways), and research on intravitreal biologic therapy for uveitis and AMD will continue to expand. With over 25 ongoing clinical trials on intravitreal biologic therapy for AMD, enthusiasm for vanguard biologic therapies should be tempered by judicious monitoring for adverse events. Conclusion: The importance of the CATT trial encompasses day-to-day treatment decisions for AMD, as well as lessons on how biologics for ocular disease should be implemented into clinical practice. Specifically, the introduction of intravitreal biologic therapies into clinical practice for uveitis, AMD, and other ocular diseases in which inflammation is involved should be guided by a clear understanding of the immunotherapeutic agent and its molecular target and with rigorous monitoring for both patient benefit and patient safety.
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder caused by a premutation CGG repeat expansion (55–200 repeats) within the 5′ UTR of the fragile X gene (FMR1). FXTAS is characterized by intension tremor, cerebellar ataxia, progressive neurodegeneration, parkinsonism and cognitive decline. The development of transgenic mouse and Drosophila melanogaster models carrying an expanded CGG repeat has yielded valuable insight into the pathophysiology of FXTAS. To date, we know of two main molecular mechanisms of this disorder: (1) a toxic gain of function of the expanded CGG-repeat FMR1 mRNA, which results in the binding/sequestration of the CGG-binding proteins; and (2) CGG repeat-associated non-AUG-initiated (RAN) translation, which generates a polyglycine peptide toxic to cells. Besides these CGG-mediated mechanisms, recent studies have shed light on additional mechanisms of pathogenesis, such as the antisense transcript ASFMR1, mitochondrial dysfunction, DNA damage from R-loop formation and 5-hydroxymethylcytosine (5hmC)-mediated epigenetic modulation. Here we summarize the recent progress towards understanding the etiology of FXTAS and provide an overview of potential treatment strategies.
Purpose: To identify risk factors for a severe uveitis course among children with non-infectious uveitis.
Design: Retrospective cohort study
Method: This was a retrospective analysis of a prospectively collected database. Records of 94 children with uveitis were reviewed at enrollment and every 3-6 months (2011-2015). Severe uveitis was defined as a history of ocular complications or a visual acuity (VA) of ≤20/200. Children were compared by disease, VA, complications and race. Regression models were used to model risk factors for severe disease. When examining race, we focused on non-Hispanic African American and non-Hispanic White children only.
Results: Of 85 children with uveitis and complete ocular examinations, 27 (32%) had a history of a VA of ≤20/200. A subanalysis of non-Hispanic African American and White children showed an increased prevalence of VA ≤20/200 in non-Hispanic African Americans (18/25 (72%) vs. 4/43 (9%)). Non-Hispanic African Americans were more likely to be diagnosed at an older age (p=0.030), have intermediate uveitis (p=0.026), bilateral disease (p=0.032), a history of VA ≤20/50 (p=0.002), VA ≤20/200 (p<0.001), and a higher rate of complications (p<0.001). On multivariable analysis, non-Hispanic African American race was a significant predictor of blindness (OR=31.6, 95% CI (5.9– 168.5), p<0.001), after controlling for uveitis duration. Non-Hispanic African Americans also developed 2.2 times more unique complications per year of disease than non-Hispanic Whites when controlling for uveitis type and duration.
Conclusions: There appear to be racial differences in the outcomes of children with uveitis. Non-Hispanic African American children with non-juvenile idiopathic arthritis associated uveitis may have worse visual outcomes with increased vision loss and ocular complications. These findings highlight the need for future studies in minority populations.
Purpose: We report endothelial cell (EC) characteristics and central corneal thickness (CCT) from Infant Aphakia treatment Study (IATS) patients at the 5-year exam.
Design: Randomized, controlled trial of the treatment of unilateral cataract with aphakic contact lens (CL) versus primary intraocular lens implant (IOL).
Subjects: 114 infants with unilateral cataract.
Methods: EC density, coefficient of variation (CV), and percent hexagonal cells were measured by non-contact specular microscopy. Central corneal thickness (CCT) was measured using contact pachymetry. Fellow eyes served as controls.
Main outcome measures: Mean differences between treated and fellow eyes of CL and IOL groups were compared with a paired t test. A one-way analysis of variance model and the Tukey-Kramer multiple comparison procedure were used to assess the effect of a diagnosis of glaucoma or glaucoma suspect.
Results: 105 (52 CL, 53 IOL) had either specular microscopy or corneal thickness data recorded. Mean EC densities were higher in the aphakic eyes compared to fellow eyes (3921 and 3495 cells/mm2, p < 0.0001). Mean CV was higher in aphakic eyes (27 vs 24, p=0.0002), and mean percent hexagonal cells was lower (72% vs 76%, p=0.002). Mean CCT of aphakic eyes was higher than controls (637 vs 563 μm, p < 0.0001). There was no difference in EC densisty in eyes treated with IOL compared to fellow eyes (3445 and 3487 cells/mm2, p=0.68). Means for CV (25 vs 24, p=0.07) and percent hexagonal cells (74 vs 76%, p=0.27) were also not significantly different. Mean CCT was higher in eyes with IOL (605 vs 571 μm, p < 0.0001) compared to fellow eyes. Compared to treated eyes without glaucoma or glaucoma suspect, treated eyes with glaucoma had lower EC density (3289 vs 3783 cells/mm2, p = 0.03) and treated eyes with glaucoma suspect had greater mean corneal thickness (660 vs 612 μm, p = 0.0036).
Conclusion: Cataract extraction during infancy with IOL implantation was not associated with a reduced EC count in treated compared to fellow eyes, although CCT was increased. Extended wear aphakic CL may cause corneal polymegathism with increased EC density and CCT. Glaucoma diagnosis was associated with reduced EC counts and increased CCT.
Neonatal aphakia is associated with retardation of the axial elongation of the neonatal eye. In contrast, form deprivation increases axial elongation, an effect that has been associated with decreased retinal dopamine metabolism. The present investigation was conducted to test the hypothesis that neonatal aphakia induces an effect on the levels of retinal dopamine opposite to form deprivation. Lensectomy and vitrectomy were performed on the right eyes of rhesus monkeys at approximately 1 week of age; their left eyes were unmanipulated. Axial length was measured by A-scan ultrasonography. Prior to surgery, mean axial length of the right and left eyes was identical. Following lens removal, both eyes continued to elongate, however the aphakic eyes elongated at a slower rate resulting in a significant shorter axial length compared to that of the unmanipulated eye. Removal of the crystalline lens had no effect on steady-state dopamine levels in either central or peripheral retina. However, levels of the dopamine metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid were significantly elevated in central retina, but not in the peripheral retina of aphakic eyes. Our results support the hypothesis that dopamine is a component of the retinal signaling pathways that are involved in the regulation of eye growth and emmetropization.
by
Malini Veerappan;
Abdul-Karim M. El-Hage-Sleiman;
Vincent Tai;
Stephanie J. Chiu;
Katrina P. Winter;
Sandra S. Stinnett;
Thomas S. Hwang;
G Baker Hubbard;
Michelle Michelson;
Randall Gunther;
Wai T. Wong;
Emily Y. Chew;
Cynthia A. Toth
Purpose Structural and compositional heterogeneity within drusen comprising lipids, carbohydrates, and proteins have been previously described. We sought to detect and define phenotypic patterns of drusen heterogeneity in the form of optical coherence tomography–reflective drusen substructures (ODS) and examine their associations with age-related macular degeneration (AMD)–related features and AMD progression. Design Retrospective analysis in a prospective study. Participants Patients with intermediate AMD (n = 349) enrolled in the multicenter Age-Related Eye Disease Study 2 (AREDS2) ancillary spectral-domain optical coherence tomography (SD OCT) study. Methods Baseline SD OCT scans of 1 eye per patient were analyzed for the presence of ODS. Cross-sectional and longitudinal associations of ODS presence with AMD-related features visible on SD OCT and color photographs, including drusen volume, geographic atrophy (GA), and preatrophic features, were evaluated for the entire macular region. Similar associations were also made locally within a 0.5-mm-diameter region around individual ODS and corresponding control region without ODS in the same eye. Main Outcome Measures Preatrophy SD OCT changes and GA, central GA, and choroidal neovascularization (CNV) from color photographs. Results Four phenotypic subtypes of ODS were defined: low reflective cores, high reflective cores, conical debris, and split drusen. Among the 349 participants, there were 307 eligible eyes and 74 (24%) had at least 1 ODS. The ODS at baseline were associated with (1) greater macular drusen volume at baseline (P < 0.001), (2) development of preatrophic changes at year 2 (P = 0.001–0.01), and (3) development of macular GA (P = 0.005) and preatrophic changes at year 3 (P = 0.002–0.008), but not development of CNV. The ODS at baseline in a local region were associated with (1) presence of preatrophy changes at baseline (P = 0.02–0.03) and (2) development of preatrophy changes at years 2 and 3 within the region (P = 0.008–0.05). Conclusions Optical coherence tomography–reflective drusen substructures are optical coherence tomography–based biomarkers of progression to GA, but not to CNV, in eyes with intermediate AMD. Optical coherence tomography–reflective drusen substructures may be a clinical entity helpful in monitoring AMD progression and informing mechanisms in GA pathogenesis.