Diplopia in the Younger Adult (≤65 Years Old) Compared With Older Adult (>65 Years Old) Population-Presentation, Progression, and Outcome.

BACKGROUND: Despite the impact of new-onset diplopia on the quality of life, there are few studies concerning new-onset diplopia in seniors. This study aimed to describe the epidemiology, etiology, prognosis, and outcome of different treatments in the older adults compared with younger adult patients presenting with new-onset binocular diplopia. METHODS: A retrospective chart review of patients ≥18 YO with new-onset binocular diplopia presenting between 2010 and 2021. Data collected included age at presentation, gender, duration of time since diplopia onset, imaging results, known trigger, etiology, treatment, and follow-up. RESULTS: Two hundred ten patients were included. Of them, 75 patients were ≤65 YO (35.7%, the "younger adult group") and 135 > 65 YO (64.3%, the "older adults group"). The common etiology in both groups was neurogenic (54.7% ≤ 65 vs 62.2% >65, P = 0.29). Cranial nerve palsies were more commonly microvascular in the older adults (96.0% vs 74.1%, P = 0.005), whereas tumor-related cranial nerve palsies were more frequent in younger adults (14.81% vs 2.04%, P = 0.03). A restrictive etiology was observed in 20% of younger adult compared with 11.1% of older adults group (P = 0.08). Sagging eye syndrome (SES) was the second most common etiology in the older adults group at 11.9%, compared with 1.3% in the younger adult group (P = 0.01). Decompensated phoria/tropia appeared in 16% of younger adult group compared with 11.9% of older adults (P = 0.4), with an obvious trigger (mostly cataract surgery) in the latter (80% older adults vs 20% younger adults, P = 0.019). Positive imaging findings were found in 46.7% of patients ≤65 compared with 25.3% of >65 (P = 0.01) and complete spontaneous resolution of diplopia was noted in 32.1% of the older adults compared with 11.8% of younger adults (P = 0.003). CONCLUSIONS: Neurogenic diplopia was the most common etiology for both groups, but is more prominent in the older adults. Noticeable findings in the older adults were SES diagnosis, identification of triggers for impaired fusion/diplopia, and a paucity of positive findings in imaging results. It is important to know these differences not only for managing seniors better, but also to minimize symptoms of binocular diplopia after lens-related procedures.

[CASE SERIES OF EARLY NEUROIMAGING IN PATIENTS WITH VASCULAR RISK FACTORS AND ISOLATED SIX CRANIAL NERVE PALSY, DEMONSTRATING THE DILEMMA OF EARLY IMAGING].

INTRODUCTION: There are various etiologies for isolated third, fourth and sixth cranial nerve palsies. The most common etiology in adults aged 50 years and older with vascular risk factors such as diabetes, hyperlipidemia, and hyperlipidemia, is microvascular ischemia. The role of early neuroimaging in older patients with vascular risk factors presenting with acute isolated ocular motor nerve palsy is controversial. AIMS: We present six cases of patients aged 50 years and older, with vascular risk factors, who suffered from acute isolated paralysis of the sixth nerve. All cases were diagnosed with a non-microvascular ischemia etiology. RESULTS: The identified etiologies included petroclival meningioma with involvement of the cavernous sinus, metastatic hepatoma, plasmacytoma, venous thrombosis, arterial-venous malformation and aneurysm. CONCLUSIONS: Despite the high cost and presumed low yield, early neuroimaging can change the clinical management in certain cases. DISCUSSION: Previous studies have found the yield of early neuroimaging in older vasculopathic patients with acute 4th or 6th cranial nerve palsies to be 1-15%. In spite of these reports, our cases demonstrate the need for early onset imaging in these cases.

Clinical profile of 80-year-old and older thyroid eye disease patients.

PURPOSE: Thyroid eye disease (TED), an autoimmune orbital disorder, follows a time-of-onset bimodal peak: 40-44 and 60-64 years for women, 45-49 and 65-69 years for men. TED, however, can also commence in old age. The study's purpose was to evaluate TED in octo- and nonagenarians. METHODS: Medical records of 19 ≥ 80 years geriatric patients at time of diagnosis were compared to 122 TED patients, aged 20-79. A second analysis was performed after subdividing the control group into two age groups, ≤ 40 ("young group," 16 patients) and 41-79 years ("middle-aged group," 106 patients). RESULTS: The geriatric group's mean age was 84 years (80-94), 11 males and 8 females. Mean follow-up time was 16 months. Compared to the controls, the geriatric patients smoked less (p = 0.012), were more often hypothyroid (p = 0.019), and had concurrent myasthenia gravis (p = 0.02) at time of diagnosis. Diplopia was the most common presenting symptom among the elderly (p = 0.005) and proptosis among the controls, specifically the young group (p = 0.027). Bilateral signs were more common among seniors (p = 0.049). Optic neuropathy was diagnosed in 10% of the geriatric group (2/19) and 11% of middle-aged group (12/106), all being resolved after steroids or orbital decompression. Active disease (clinical activity score (CAS) score = > 3) was more common among the middle-aged group (p = 0.024) while the geriatric patients tended towards higher TED severity grades. Orbital decompression and eyelid repositioning surgeries were more common among the middle-aged group. Strabismus surgeries were more common among seniors. CONCLUSIONS: TED among octo- and nonagenarians has unique patterns, with different demographic features, more exposed to diplopia, hypothyroidism, association with myasthenia gravis, and bilateral involvement. Special attention should be given when medically managing this subgroup.

Electric-field tuning of the surface band structure of topological insulator Sb2Te3 thin films.

We measured the response of the surface state spectrum of epitaxial Sb(2)Te(3) thin films to applied gate electric fields by low temperature scanning tunneling microscopy. The gate dependent shift of the Fermi level and the screening effect from bulk carriers vary as a function of film thickness. We observed a gap opening at the Dirac point for films thinner than four quintuple layers, due to the coupling of the top and bottom surfaces. Moreover, the top surface state band gap of the three quintuple layer films was found to be tunable by a back gate, indicating the possibility of observing a topological phase transition in this system. Our results are well explained by an effective model of 3D topological insulator thin films with structure inversion asymmetry, indicating that three quintuple layer Sb(2)Te(3) films are topologically nontrivial and belong to the quantum spin Hall insulator class.

Experimental evidence for s-wave pairing symmetry in superconducting Cu(x)Bi2Se3 single crystals using a scanning tunneling microscope.

Topological superconductors represent a newly predicted phase of matter that is topologically distinct from conventional superconducting condensates of Cooper pairs. As a manifestation of their topological character, topological superconductors support solid-state realizations of Majorana fermions at their boundaries. The recently discovered superconductor Cu(x)Bi(2)Se(3) has been theoretically proposed as an odd-parity superconductor in the time-reversal-invariant topological superconductor class, and point-contact spectroscopy measurements have reported the observation of zero-bias conductance peaks corresponding to Majorana states in this material. Here we report scanning tunneling microscopy measurements of the superconducting energy gap in Cu(x)Bi(2)Se(3) as a function of spatial position and applied magnetic field. The tunneling spectrum shows that the density of states at the Fermi level is fully gapped without any in-gap states. The spectrum is well described by the Bardeen-Cooper-Schrieffer theory with a momentum independent order parameter, which suggests that Cu(x)Bi(2)Se(3) is a classical s-wave superconductor contrary to previous expectations and measurements.

Single-molecule-resolved structural changes induced by temperature and light in surface-bound organometallic molecules designed for energy storage.

We have used scanning tunneling microscopy, Auger electron spectroscopy, and density functional theory calculations to investigate thermal and photoinduced structural transitions in (fulvalene)tetracarbonyldiruthenium molecules (designed for light energy storage) on a Au(111) surface. We find that both the parent complex and the photoisomer exhibit striking thermally induced structural phase changes on Au(111), which we attribute to the loss of carbonyl ligands from the organometallic molecules. Density functional theory calculations support this conclusion. We observe that UV exposure leads to pronounced structural change only in the parent complex, indicative of a photoisomerization reaction.

Functionalization, self-assembly, and photoswitching quenching for azobenzene derivatives adsorbed on Au(111).

We have used scanning tunneling microscopy to investigate the structure and photoswitching behavior of azobenzene molecules functionalized with bulky spacer groups and adsorbed onto Au(111). We find that positioning tert-butyl "legs" in a canted arrangement on the azobenzene phenyl rings quenches photoisomerizability of the molecule on Au(111). Addition of cyano groups at the para positions changes the molecular self-assembly significantly, but does not alter the quenched photoisomerizability. This behavior likely arises from a combination of molecule-surface interactions, molecule-molecule interactions, and alteration of azobenzene electronic structure resulting from the position-specific addition of tert-butyl groups.

Determination of photoswitching dynamics through chiral mapping of single molecules using a scanning tunneling microscope.

Single-molecule-resolved scanning tunneling microscopy of tetra-tert-butyl azobenzene (TTB-AB) molecules adsorbed onto Au(111) reveals chirality selection rules in their photoswitching behavior. This observation is enabled by the fact that trans-TTB-AB molecules self-assemble into homochiral domains. Cis-TTB-AB molecules produced via photoisomerization are found in two distinct conformations with final state chirality determined by the initial trans isomer chirality. Based on these observations and ab initio calculations, we propose a new inversion-based dynamical photoswitching mechanism for azobenzene molecules at a surface.

Surface anchoring and dynamics of thiolated azobenzene molecules on Au(111).

We have investigated the temperature-dependent behavior of thiolated azobenzene molecules on Au(111) using scanning tunneling microscopy. The addition of a thiol functional group to azobenzene molecules leads to increased surface anchoring of single azobenzene molecules to gold. Thiolated azobenzene shows diverse surface morphology and does not form well-ordered structures at low coverage. At elevated temperatures, anchored molecules are observed to spin in place via hindered rotation. By measuring the number of rotating molecules as a function of temperature and using a simple model, we are able to estimate the energy barrier and attempt frequency for thermally induced hindered rotation to be 102+/-3 meV and 110+/-2 GHz, respectively.

Self-patterned molecular photoswitching in nanoscale surface assemblies.

Photomechanical switching (photoisomerization) of molecules at a surface is found to strongly depend on molecule-molecule interactions and molecule-surface orientation. Scanning tunneling microscopy was used to image photoswitching behavior in the single-molecule limit of tetra-tert-butyl-azobenzene molecules adsorbed onto Au(111) at 30 K. Photoswitching behavior varied strongly with surface molecular island structure, and self-patterned stripes of switching and nonswitching regions were observed having approximately 10 nm pitch. These findings can be summarized into photoswitching selection rules that highlight the important role played by a molecule's nanoscale environment in determining its switching properties.

Reversible photomechanical switching of individual engineered molecules at a metallic surface.

We have observed reversible light-induced mechanical switching for individual organic molecules bound to a metal surface. Scanning tunneling microscopy (STM) was used to image the features of individual azobenzene molecules on Au(111) before and after reversibly cycling their mechanical structure between trans and cis states using light. Azobenzene molecules were engineered to increase their surface photomechanical activity by attaching varying numbers of tert-butyl (TB) ligands ("legs") to the azobenzene phenyl rings. STM images show that increasing the number of TB legs "lifts" the azobenzene molecules from the substrate, thereby increasing molecular photomechanical activity by decreasing molecule-surface coupling.