Resolution enhancement with deblurring by pixel reassignment (DPR).

Improving the spatial resolution of a fluorescence microscope has been an ongoing challenge in the imaging community. To address this challenge, a variety of approaches have been taken, ranging from instrumentation development to image post-processing. An example of the latter is deconvolution, where images are numerically deblurred based on a knowledge of the microscope point spread function. However, deconvolution can easily lead to noise-amplification artifacts. Deblurring by post-processing can also lead to negativities or fail to conserve local linearity between sample and image. We describe here a simple image deblurring algorithm based on pixel reassignment that inherently avoids such artifacts and can be applied to general microscope modalities and fluorophore types. Our algorithm helps distinguish nearby fluorophores even when these are separated by distances smaller than the conventional resolution limit, helping facilitate, for example, the application of single-molecule localization microscopy in dense samples. We demonstrate the versatility and performance of our algorithm under a variety of imaging conditions.

High-resolution multi-z confocal microscopy with a diffractive optical element.

There has been recent interest in the development of fluorescence microscopes that provide high-speed volumetric imaging for life-science applications. For example, multi-z confocal microscopy enables simultaneous optically-sectioned imaging at multiple depths over relatively large fields of view. However, to date, multi-z microscopy has been hampered by limited spatial resolution owing to its initial design. Here we present a variant of multi-z microscopy that recovers the full spatial resolution of a conventional confocal microscope while retaining the simplicity and ease of use of our initial design. By introducing a diffractive optical element in the illumination path of our microscope, we engineer the excitation beam into multiple tightly focused spots that are conjugated to axially distributed confocal pinholes. We discuss the performance of this multi-z microscope in terms of resolution and detectability and demonstrate its versatility by performing in-vivo imaging of beating cardiomyocytes in engineered heart tissues and neuronal activity in c. elegans and zebrafish brains.

The correlation of retinal neurodegeneration and brain degeneration in patients with Alzheimer's disease using optical coherence tomography angiography and MRI.

Introduction: Pathological changes in Alzheimer's disease can cause retina and optic nerve degeneration. The retinal changes are correlated with cognitive function. This study aimed to explore the relationship of retinal differences with neuroimaging in patients with Alzheimer's disease, analyze the association of cognitive function with retinal structure and vascular density, and identify potential additional biomarkers for early diagnosis of Alzheimer's disease. Method: We performed magnetic resonance imaging (MRI) scans and neuropsychological assessments in 28 patients with mild Alzheimer's disease and 28 healthy controls. Retinal structure and vascular density were evaluated by optical coherence tomography angiography (OCTA). Furthermore, we analyzed the correlation between neuroimaging and OCTA parameters in patients with mild Alzheimer's disease with adjustment for age, gender, years of education, and hypertension. Results: In patients with mild Alzheimer's disease, OCTA-detected retinal parameters were not significantly correlated with MRI-detected neuroimaging parameters after Bonferroni correction for multiple testing. Under multivariable analysis controlled for age, gender, years of education, and hypertension, the S-Hemi (0-3) sector of macular thickness was significantly associated with Mini-cog (ß = 0.583, P = 0.002) with Bonferroni-corrected threshold at P < 0.003. Conclusion: Our findings suggested decreased macular thickness might be associated with cognitive function in mild AD patients. However, the differences in retinal parameters didn't correspond to MRI-detected parameters in this study. Whether OCTA can be used as a new detection method mirroring MRI for evaluating the effect of neuronal degeneration in patients with mild Alzheimer's disease still needs to be investigated by more rigorous and larger studies in the future.

New Endothelial Corneal Dystrophy in a Chinese Family.

PURPOSE: The aim of this study was to characterize the clinical presentation of atypical endothelial corneal dystrophy (ECD) and to identify possible associated genetic variants in a Chinese family. METHODS: Six affected members, 4 unaffected first-degree relatives, and 3 spouses who were enrolled in this study underwent ophthalmic examinations. Genetic linkage analysis was performed for 4 affected and 2 unaffected members, and whole-exome sequencing (WES) was performed for 2 patients to identify disease-causing variants. Candidate causal variants were verified using Sanger sequencing in family members and 200 healthy controls. RESULTS: The mean age at disease onset was 16.5 years. The early phenotype of this atypical ECD was characterized by multiple small white translucent spots located in Descemet membrane of the peripheral cornea. These spots coalesced to form opacities with variable shapes, and eventually merged along the limbus. Subsequently, translucent spots appeared in central Descemet membrane and accumulated, causing diffuse polymorphous opacities over time. Finally, significant endothelial decompensation led to diffuse corneal edema. A heterozygous missense variant in the KIAA1522 gene (c.1331G>A; p.R444Q) was identified by WES, which was present in all 6 patients but was absent in the unaffected members and healthy controls. CONCLUSIONS: The clinical features of atypical ECD are unique compared with those of known corneal dystrophies. Moreover, genetic analysis identified the c.1331G>A variant in KIAA1522 , which may be responsible for the pathogenesis of this atypical ECD. Thus, we propose this is a new form of ECD based on our clinical findings.

Vascular Risk Factors in Isolated Microvascular Ischemic Third Nerve Palsy: A Population-Based Study.

BACKGROUND: Although presumed microvascular third nerve palsies (TNP) have been associated with vascular risk factors and/or stroke, these associations have not been explored in a population-based cohort. The purpose of this population-based case-control study was to determine whether these factors are associated with TNPs that had been classified as isolated microvascular ischemic events and determine future risk of mortality. METHODS: Participants were subjects >18 years old with new onset of isolated TNP attributed to presumed microvascular ischemia (n = 55) while residing in Olmsted County, Minnesota, from January 1, 1978 to December 31, 2014. Control subjects (n = 55) were randomly selected from the same population and matched for gender, age, and length of medical follow-up. We identified all cases of new-onset isolated presumed microvascular ischemic TNP using the Rochester Epidemiology Project, a record-linkage system of medical records for all patient-physician encounters in Olmsted County, Minnesota. All medical records of cases and controls were reviewed for potential risk factors, including diabetes mellitus, diabetic retinopathy, hypertension, hyperlipidemia, smoking, and symptomatic ischemic stroke. Multivariable and univariate logistic regression analyses were used to compare the prevalence of potential risk factors between microvascular ischemic cases and controls according to the number of subjects, and odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Kaplan-Meier curves were used to compare mortality between cases and controls. RESULTS: The annual incidence of microvascular ischemic TNP was 1.7 per 100,000. Univariate analysis demonstrated that hypertension ( P < 0.001; OR, 4.80; 95% CI, 2.11-11.58), diabetes mellitus ( P < 0.001; OR, 6.55; 95% CI, 2.72-17.32), diabetic retinopathy ( P = 0.014; OR, 13.50; 95% CI, 2.48-251.55), coronary artery disease ( P = 0.047; OR, 2.27; 95% CI, 1.02-5.18), and symptomatic ischemic stroke ( P = 0.039; OR, 3.56; 95% CI, 1.07-11.85) all occurred more frequently in patients with microvascular ischemic TNP than controls. In multivariate analysis, only hypertension (OR of 4.14, 95% CI, 1.61-10.65, P < 0.001) and diabetes (OR of 4.12, 95% CI, 1.43-11.92, P = 0.003) remained independently statistically significant. There was numerically higher mortality in microvascular cases than in controls, but it did not reach statistical significance. CONCLUSIONS: There are multiple cardiovascular diseases that are associated with isolated microvascular ischemic TNP, including hypertension, coronary artery disease, diabetes mellitus, diabetic retinopathy, and symptomatic ischemic stroke. Given that the main drivers of this association seem to be diabetes and hypertension, patients with microvascular ischemic TNP should be evaluated for these conditions.

Resolution enhancement with deblurring by pixel reassignment.

Improving the spatial resolution of a fluorescence microscope has been an ongoing challenge in the imaging community. To address this challenge, a variety of approaches have been taken, ranging from instrumentation development to image postprocessing. An example of the latter is deconvolution, where images are numerically deblurred based on a knowledge of the microscope point spread function. However, deconvolution can easily lead to noise-amplification artifacts. Deblurring by postprocessing can also lead to negativities or fail to conserve local linearity between sample and image. We describe here a simple image deblurring algorithm based on pixel reassignment that inherently avoids such artifacts and can be applied to general microscope modalities and fluorophore types. Our algorithm helps distinguish nearby fluorophores, even when these are separated by distances smaller than the conventional resolution limit, helping facilitate, for example, the application of single-molecule localization microscopy in dense samples. We demonstrate the versatility and performance of our algorithm under a variety of imaging conditions.

Increased rate of ptosis following glaucoma drainage device placement and other anterior segment surgery: a prospective analysis.

PURPOSE: To determine the degree and rate of ptosis in patients undergoing glaucoma and cataract surgery. METHODS: Patients undergoing cataract extraction (CE), trabeculectomy, or glaucoma drainage device (GDD) placement, or a combination, were consecutively enrolled by a sole surgeon. Eyelid measurements, including margin reflex distance 1 (MRD1) and levator function, were obtained preoperatively and at 1 and 3 months postoperatively. Primary outcome measures were the change in MRD1 pre- vs postoperatively; percentage of patients with ptosis (defined as MRD1 < 2 mm pre- vs postoperatively). Secondary measures were the absolute change in MRD1 between groups, decrease in MRD1 of ≥ 2 mm, and change in levator function. RESULTS: In total, 104 eyes of 73 patients underwent CE, trabeculectomy, or GDD placement and completed at least 1-month follow-up; 93 eyes of 65 patients completed 3-month follow-up. MRD1 decreased significantly in trabeculectomy and GDD groups at 1 and 3 months postoperatively, while it did not change in the CE group. The GDD group had a significant increase in percentage of patients with ptosis at 3 months postoperatively. CONCLUSION: Patients who underwent glaucoma surgery, especially those who underwent GDD placement, were more likely to have postoperative ptosis than patients undergoing CE alone. High ptosis rates in patients undergoing glaucoma surgery may warrant preoperative counseling and post-operative referral to oculoplastic surgeons.

Telemedicine in long-term care of glaucoma patients.

Introduction: This manuscript describes data from an original study, simulating a tele-glaucoma programme in an established clinic practice with an interdisciplinary team. This is a 'real life' trial of a telemedicine approach to see a follow-up patient. The goal is to evaluate the accuracy of such a programme to detect worsening and/or unstable disease. Such a programme is attractive since in-clinic time could be reduced for both the patient and provider. This study evaluates agreement between in-person and remote assessment of glaucoma progression. Methods: A total of 200 adult glaucoma patients were enrolled at a single institution. The in-person assessment by an optometrist or glaucoma specialist at time of enrolment was used as the gold standard for defining progression. Collated clinical data were then reviewed by four masked providers who classified glaucoma as progression or non-progression in each eye by comparing data from enrolment visit to data from the visit immediately prior to enrolment. Agreement of glaucoma progression between the masked observer and the in-person assessment was determined using Kappa statistics. Intra-observer agreement was calculated using Kappa to compare in-person to remote assessment when both assessments were performed by the same provider (n = 279 eyes). Results: A total of 399 eyes in 200 subjects were analysed. Agreement between in-person versus remote assessment for the determination of glaucoma progression was 63%, 62%, 69% and 68% for each reader 1­4 (kappa values = 0.19, 0.20, 0.35 and 0.33, respectively). For intra-observer agreement, reader 1 agreed with their own in-person assessment for 65% of visits (kappa = 0.18). Discussion: Intra-observer agreement was similar to the agreement for each provider who did not see the patient in person. This similarity suggests that telemedicine may be equally effective at identifying glaucomatous disease progression, regardless of whether the same provider performed both in-clinic and remote assessments. However, fair agreement levels highlight a limitation of using only telemedicine data to determine progression compared with clinical detail available during in-patient assessment.

Analysis of Foveal Microvascular Abnormalities in Diabetic Retinopathy Using Optical Coherence Tomography Angiography with Projection Artifact Removal.

PURPOSE: To analyze foveal microvascular abnormalities in different stages of diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA) with projection artifact removal (PAR). METHODS: We analyzed 93 eyes of 59 patients with diabetes-31 with no DR (no DR), 34 with mild to moderate nonproliferative DR (mild DR), and 28 with severe nonproliferative DR to proliferative DR (severe DR)-and 31 age-matched healthy controls. Sections measuring 3 × 3 mm2 centered on the fovea were obtained using OCTA. The area, perimeter, and acircularity index (AI) of the foveal avascular zone (FAZ), vessel density within a 300 µm wide region of the FAZ (FD-300), and parafoveal vessel density in the superficial capillary plexus (SCP) and deep capillary plexus (DCP) were calculated using novel built-in software with PAR. RESULTS: There was no statistically significant difference in the FAZ area (p=0.162). There was a statistically significant difference in the FAZ perimeter (p=0.010) and the AI (p < 0.001) between the four groups. There was a correlation between the AI and the increasing severity of DR (p=0.010). Statistically significant decreases of vessel density in the FD-300, SCP, and DCP were observed (all p < 0.001). There was a difference in parafoveal vessel density in the DCP between the healthy control eyes and the eyes with diabetes without DR (p=0.027). There was a significant correlation between vessel density and increasing severity of DR (p < 0.001). CONCLUSION: Compared with the FAZ area, AI allows a more helpful quantitative assessment of the changes in the FAZ. Vessel density determined using OCTA with PAR might be a useful parameter indicating the progression of DR. Parafoveal vessel density in the DCP after PAR might be a potential early biomarker of DR before appearance of clinically evident retinopathy and needs further investigation.

Provider Agreement in the Assessment of Glaucoma Progression Within a Team Model.

PURPOSE: Glaucoma specialists and optometrists who work in a team model at a single institution utilize a common definition of glaucoma progression and treatment algorithm. The purpose of this study was to assess the consistency of agreement in identifying glaucoma progression among glaucoma specialists and optometrists of 1 team. METHODS: In total, 399 eyes of 200 patients age 18 or older with glaucoma were enrolled over 2 years. Clinical data, disc photographs, optical coherence tomography (OCT), and visual fields were independently reviewed by 2 masked optometrists and 2 masked fellowship-trained glaucoma specialists. Each eye was judged as progression or no progression of glaucomatous disease. The following were assessed: (1) agreement among optometrists; (2) agreement among glaucoma specialists; and (3) agreement among optometrists and glaucoma specialists. The frequency of use of testing modality to determine progression was also studied. κ statistics were used to evaluate agreements. RESULTS: Optometrists agreed with each other for 74.2% of the eyes assessed (κ=0.42), whereas glaucoma specialists agreed with each other for 78.7% of eyes (κ=0.39). All 4 providers agreed with each other for 54.4% of the eyes evaluated (κ=0.37). Providers had the highest agreement when the progression decision was based on disc hemorrhage (92%) and the lowest agreement when based on OCT progression analysis (36%). Compared with optometrists, glaucoma specialists used OCT (P≤0.01) more frequently to determine disease progression. CONCLUSIONS: Fair to moderate agreement levels were found among providers in their assessment of glaucoma progression, suggesting that a team approach to glaucoma management may be effective. Further work is needed to investigate ways to optimize consistency within the glaucoma team.

SMILE and Wavefront-Guided LASIK Out-Compete Other Refractive Surgeries in Ameliorating the Induction of High-Order Aberrations in Anterior Corneal Surface.

Purpose. To compare the change of anterior corneal higher-order aberrations (HOAs) after laser in situ keratomileusis (LASIK), wavefront-guided LASIK with iris registration (WF-LASIK), femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK), and small incision lenticule extraction (SMILE). Methods. In a prospective study, 82 eyes underwent LASIK, 119 eyes underwent WF-LASIK, 88 eyes underwent FS-LASIK, and 170 eyes underwent SMILE surgery. HOAs were measured with Pentacam device preoperatively and 6 months after surgery. The aberrations were described as Zernike polynomials, and analysis focused on total HOAs, spherical aberration (SA), horizontal coma, and vertical coma over 6 mm diameter central corneal zone. Results. Six months postoperatively, all procedures result in increase of anterior corneal total HOAs and SA. There were no significant differences in the induced HOAs between LASIK and FS-LASIK, while SMILE induced fewer total HOAs and SA compared with LASIK and FS-LASIK. Similarly, WF-LASIK also induced less total HOAs than LASIK and FS-LASIK, but only fewer SA than FS-LASIK (P < 0.05). No significant difference could be detected in the induced total HOAs and SA between SMILE and WF-LASIK, whereas SMILE induced more horizontal coma and vertical coma compared with WF-LASIK (P < 0.05). Conclusion. FS-LASIK and LASIK induced comparable anterior corneal HOAs. Compared to LASIK and FS-LASIK, both SMILE and WF-LASIK showed advantages in inducing less total HOAs. In addition, SMILE also possesses better ability to reduce the induction of SA in comparison with LASIK and FS-LASIK. However, SMILE induced more horizontal coma and vertical coma compared with WF-LASIK, indicating that the centration of SMILE procedure is probably less precise than WF-LASIK.

Apolipoprotein E gene ε4ε4 is associated with elevated risk of primary open angle glaucoma in Asians: a meta-analysis.

BACKGROUND: Epidemiological studies have evaluated the association between Apolipoprotein E (APOE) gene ε2/ε3/ε4 polymorphism and glaucoma susceptibility. However, the published data are still inconclusive. The aim of the present study is to evaluate the impact of APOE gene ε2/ε3/ε4 polymorphism on glaucoma risk by using meta-analysis. METHODS: A comprehensive literature search of PubMed, EMBASE, Cochrane, Elsevier Science Direct and CNKI databases was conducted to identify relevant articles, with the last report up to January 5, 2014. Pooled odds ratio (OR) and 95% confidence interval (CI) were used to assess the strength of association by using the fixed or random effect model. RESULTS: Fifteen separate studies including 2,700 cases and 2,365 controls were included in the meta-analysis. We did not detect a significant association between APOE gene ε2/ε3/ε4 polymorphism and glaucoma in overall population (P > 0.0083). In Asians, we detected an association of the ε4ε4 genotype with elevated risk for glaucoma (OR = 5.22, 95% CI = 1.85-14.68, P = 0.002), mainly for primary open angle glaucoma (OR = 4.98, 95% CI = 1.75-14.20, P = 0.003). CONCLUSIONS: The meta-analysis suggests that APOE gene ε4ε4 may be associated with elevated risk for primary open angle glaucoma in Asians. However, more epidemiologic studies based on larger sample size, case-control design and stratified by ethnicity as well as types of glaucoma are suggested to further clarify the relationship between APOE gene ε2/ε3/ε4 polymorphism and genetic predisposition to glaucoma.

The expression of vascular endothelial growth factor in mast cells promotes the neovascularisation of human pterygia.

AIMS: To analyse the relationship between mast cells and vascularisation in pterygia and to determine whether mast cells play an important role in the vascularisation of pterygia through the secretion of vascular endothelial growth factor (VEGF). METHODS: Fifty-two pterygia and forty-four normal conjunctiva samples were obtained. Formalin-fixed, paraffin wax-embedded tissues were analysed by immunohistochemistry with CD31 and VEGF antibodies. Dual-immunofluorescence was used to see the location of mast cells and microvessels. To prove that mast cells have the function of secreting VEGF, we used dual-immunofluorescence, toluidine blue stain and immunohistochemisty study. RESULTS: Mast cells are located near the microvessels. The numbers of mast cells in pterygia (10.8 ± 2.7) were significantly higher compared with those in conjunctiva (4.7 ± 2.4, p<0.01). The numbers of microvessels in pterygia (20.7 ± 5.4) were also significantly higher than those in conjunctiva (9.3 ± 2.9, p<0.01). There was an association between mast cell count and microvessel density in pterygia (r=0.77, p<0.001). The cells were positive for toluidine blue staining and could express VEGF through a serial section stain. Dual-immunofluorescence showed that VEGF and mast cell tryptase (MCT) were expressed in the same cell. CONCLUSION: The results suggest that mast cells have a function in the vascularisation of pterygia through the secretion of VEGF.