One-Year and 18-Month Outcomes in nAMD Patient Eyes Switched to Brolucizumab Alone versus to Brolucizumab Alternating with Other Anti-VEGF Agents.

Objective: Retrospective, real-world study to evaluate visual acuity (VA), anti-vascular endothelial growth factor (anti-VEGF) injection intervals, and central macular thickness (CMT) in neovascular age-related macular degeneration (nAMD) eyes switched to brolucizumab only or to brolucizumab alternating with another anti-VEGF. Methods: The overall study population comprised eyes that were given ≥1 brolucizumab injection between 1 October 2019 and 30 November 2021. The brolucizumab-only (BRO) cohort consisted of prior anti-VEGF-treated eyes treated exclusively with ≥3 brolucizumab injections over ≥12 or ≥18 months; the alternating brolucizumab (ALT) cohort comprised prior anti-VEGF-treated eyes treated with ≥2 brolucizumab injections and ≥1 other anti-VEGF over ≥12 or ≥18 months. Results: A total of 482 eyes received ≥1 brolucizumab injection during the study period. Mean VA changes from baseline were -1.1±15.1 letters (BRO cohort; n = 174) and 1.3±13.0 letters (ALT cohort; n = 47) at Month 12, and 0.0±13.5 letters (BRO cohort; n = 95) and -7.3±17.2 letters (ALT cohort; n = 29) at Month 18. Mean changes in injection intervals were +26.9±48.1 days (BRO cohort) and +11.1±17.3 days (ALT cohort) at Month 12 and +36.3±52.3 days (BRO cohort) and +14.0±19.9 days (ALT cohort) at Month 18. Mean changes in CMT were -35.2±108.1 µm (BRO cohort) and -31.5±91.2 µm (ALT cohort) at Month 12 and -38.9±75.0 µm (BRO cohort) and -9.0±59.9 µm (ALT cohort) at Month 18. Intraocular inflammation-related adverse events were recorded in 22/482 (4.6%) eyes. Conclusion: Treatment with either brolucizumab alone or brolucizumab alternating with another anti-VEGF can preserve vision, reduce CMT, and extend anti-VEGF injection intervals in patients with nAMD.

Early surgical displacement of submacular hemorrhage without tissue plasminogen activator use: one-year outcomes.

OBJECTIVE: This study evaluated changes in best-corrected visual acuity and submacular hemorrhage (SMH) resolution in eyes after a single rapid subretinal displacement surgery using subretinal balanced saline solution and sterile air without tissue plasminogen activator (tPA). DESIGN: A retrospective comparative interventional analysis. PARTICIPANTS: Twenty-six eyes with thick SMH who underwent pars plana vitrectomy and subretinal fluid displacement without tPA from 2015 and 2021 and at least 1-year of follow-up. METHODS: Surgical intervention included a standard small-gauge pars plana vitrectomy with subretinal displacement using balanced saline solution with subretinal sterile air and partial gas-air fluid exchange. Main outcome measures included degree of subfoveal SMH displacement, best and final postoperative visual acuities, and adverse events. Snellen acuity was converted to logMARs for statistical analysis. RESULTS: The most common etiology associated with thick SMH (92.3%) was neovascular age-related macular degeneration. Within 1 month postoperatively, 21 patients (80.8%) saw complete subfoveal blood displacement. Most of the SMH surgical displacements were done within 1 week of presenting symptoms. Average preoperative duration of SMH was 3.60 ± 2.78 days (range, 1-12 days). Mean logMAR best-corrected visual acuity improved from 1.63 ± 0.58 (Snellen 20/800 baseline) to 0.90 ± 0.42 letters (Snellen 20/160) at last follow-up (p = 0.001). This study's visual acuity improvement is comparable with that of prior studies using tPA. Early postoperative complications included 1 retinal detachment, 1 vitreous hemorrhage, and 1 macular hole. CONCLUSION: Rapid surgery with subretinal balanced saline solution-sterile air injection without tPA was found to be effective for displacement of thick SMH with retinal function, visual acuity, and corneal refractive therapy improvement.

Switching to brolucizumab: injection intervals and visual, anatomical and safety outcomes at 12 and 18 months in real-world eyes with neovascular age-related macular degeneration.

BACKGROUND: The anti-vascular endothelial growth factor (anti-VEGF) injection interval influences treatment burden and compliance in neovascular age-related macular degeneration (nAMD). This real-world study investigates visual acuity (VA), injection-interval extension, central macular thickness (CMT) and safety in nAMD eyes switched to the anti-VEGF agent brolucizumab and followed for up to 18 months. METHODS: This retrospective study included patients with nAMD who were switched from other anti-VEGF agents to brolucizumab only. Patient eyes were grouped into three nested cohorts with the overall cohort receiving ≥ 1 brolucizumab injection, the second receiving ≥ 3 brolucizumab injections with a follow-up period of ≥ 12 months and the third cohort receiving ≥ 3 brolucizumab injections with a follow-up period of ≥ 18 months. Study endpoints included changes from baseline at 12 or 18 months in VA, injection intervals, and CMT. Sub-group analyses were conducted using baseline injection interval length or baseline VA as qualifiers. RESULTS: Overall, 482 eyes received ≥ 1 brolucizumab injection; 174 eyes received ≥ 3 brolucizumab injections with ≥ 12 months of follow-up, and 95 eyes received ≥ 3 brolucizumab injections with ≥ 18 months of follow-up. VA (mean [95% confidence intervals]) remained stable relative to baseline after 12 months (- 1.1 [- 3.7, 1.6] letters; p = 0.42) and 18 months (0.0 [- 3.1, 3.1] letters; p = 0.98) of brolucizumab treatment, respectively, and pre-switch injection intervals or baseline VA had no notable effect. Following the switch to brolucizumab, injection intervals were extended from baseline to month 12 by 26.9 (19.7, 34.0) days (p < 0.0001), and eyes with pre-switch injection intervals < 8 weeks were able to have their injection intervals extended by 23.6 days longer than eyes with pre-switch injection intervals ≥ 8 weeks. At 18 months, injection intervals were extended by 36.3 (25.6, 46.9) days (p < 0.0001) compared to baseline. Following switch to brolucizumab, CMT was reduced at both 12 and 18 months (12 months: - 35.2 (- 51.7, - 18.8) µm, p < 0.0001; 18 months: - 38.9 (- 54.3, - 22.0) µm, p < 0.0001). Intraocular inflammation-related adverse events were reported in 4.6% of brolucizumab-treated eyes. CONCLUSIONS: This real-world study demonstrates that injection intervals may be significantly extended with maintained vision and reduced CMT in nAMD eyes switching to brolucizumab therapy from other anti-VEGFs.

Comparison of Face-down Positioning Durations Following Silicone Oil Tamponade.

OBJECTIVE: To analyze the rate and timing of retinal redetachments and other complications following pars plana vitrectomy for retinal detachment repair with silicone oil tamponade and the effect of face-down positioning duration on these endpoints. MATERIALS AND METHODS: A retrospective study was performed on patients with retinal detachment repair via pars plana vitrectomy with silicone oil tamponade between 2015 and 2020. Surgery was performed by 10 physicians associated with a private retina practice in Cleveland, Ohio. Duration of postoperative face-down positioning was noted and patients were grouped by short (≤6 days) or long (≥7 days) durations. Outcome variables were retinal re-detachment, epiretinal membrane formation, cataract formation, and other complications. Timing and frequency of outcomes were noted and statistical analysis was performed. RESULTS: The study was composed of 227 eyes. The mean age of patients was 62.09±13.65 years with 143 (63.00%) male and 84 (37.00%) female. Of the initial detachments, 63 (27.88%) were macula-on and 163 (72.12%) were macula-off. Overall, 128 (56.39%) patients were given instructions for face-down positioning for 6 days or less and 99 (43.61%) patients for 7 days or more. Retinal redetachment was seen in 42.19% of patients with face-down positioning ≤6 days and 29.29% of patients with face-down positioning ≥7 days (P = .045). No significant difference was found in epiretinal membrane formation or cataract formation (P >.05). CONCLUSION: There was a lower rate of redetachment in patients who kept a face-down position for ≥7 days compared with ≤6 days. Further study to determine causality between duration of postoperative face-down positioning and retinal redetachment is recommended. [Ophthalmic Surg Lasers Imaging Retina. 2022;53:285-292.].

Frequency and Symptoms of Intravitreal Silicone Oil Droplets Following Becton Dickinson and Norm-Ject Bevacizumab Injections.

BACKGROUND AND OBJECTIVE: To determine silicone oil droplet frequency and symptomatic impact in patients injected with Norm-Ject (NJ) and/or Becton Dickinson (BD) intravitreal bevacizumab. PATIENTS AND METHODS: This was a retrospective cohort study of 426 patients with prior bevacizumab injection(s). Symptomatic floaters questionnaire responses were compiled and statistical analysis was performed using Fisher's exact t test with 95% CI calculated via the modified Wald method. RESULTS: Patients who received BD intravitreal bevacizumab showed more droplets (67.2%) than those who received NJ intravitreal bevacizumab (7.8%), and droplets increased with injection quantity. However, the symptomatic patients reporting new floaters were similar (NJ: 39.22%, BD: 39.47%). [Ophthalmic Surg Lasers Imaging Retina. 2022;53:108-112.].

Histologic Findings of Choroidal Vasculopathy in Eyes Enucleated following Radiation Therapy for Uveal Melanoma: Radiation Choroidopathy.

INTRODUCTION: Little has been published about the choroidal vascular changes that occur years after radiation exposure. The aim of this study was to review the histological changes observed in the choroidal vasculature following radiotherapy for uveal melanoma. METHODS: Records from a single institution were retrospectively reviewed from June 7, 2007 to June 7, 2017; 101 patients with a diagnosis of uveal melanoma that underwent enucleation had their records reviewed. Out of these, a total of 26 eyes had undergone plaque brachytherapy prior to enucleation, which had been performed at a mean time of 7.2 years (range from 0 years to 30 years) after the initial plaque placement. A histopathologic analysis was conducted on all 26 eyes with special emphasis on the choroidal changes. Of these 26 eyes, 18 demonstrated evidence of radiation-induced vasculopathy. RESULTS: Of the 18 eyes, 10/18 (55%) had radiation retinopathy and 16/18 (89%) had radiation choroidal vasculopathy. One patient had a phthisical eye, and the choroid could not be evaluated because the characteristics of the vasculature could not be determined. Nine cases had vitreous hemorrhage (50%), all cases had radiation retinopathy, and 8/9 (89%) had radiation choroidopathy. Of the 16 cases with radiation choroidal vasculopathy, 3/16 (19%) had only intratumoral radiation choroidal vasculopathy, 3/16 (19%) had only extratumoral radiation choroidal vasculopathy, and, thus, 10/16 (32%) had both intratumoral and extratumoral radiation choroidal vasculopathy. In patients with radiation choroidal vasculopathy, 2/16 (13%) had hyalinization of the choroidal vessels. Another 3/16 (19%) cases with radiation choroidal vasculopathy had ectatic vessels. The other 11/16 (68%) had evidence of both hyalinization of the choroidal vessels as well as ectatic vessels in the choroid. Histological evidence of radiation retinopathy and choroidopathy were seen in 69% of eyes enucleated after receiving radiation therapy, which, in some cases, also had vitreous hemorrhage. Polypoidal choroidal vasculopathy, choroidal neovascularization, and retinal choroidal anastomoses (RAP-type lesions) were seen in 12 of the 16 eyes (75%). DISCUSSION/CONCLUSION: Irradiation of malignant tumors of the eye causes not only radiation retinopathy but also radiation choroidopathy. The role of radiation choroidopathy in the subsequent visual loss following radiotherapy and the role of anti-VEGF therapy needs to be recognized and distinguished from radiation retinopathy. Our data adds to the prior limited knowledge that radiation affects the choroid and can induce specific phenotypes similar to the clinical spectrum of CNV, PCV, and RAP.

Endoscope-assisted scleral buckle procedure.

BACKGROUND: Retinal reattachment surgery requires clear visualization of the posterior segment for optimal outcomes. Select patients may benefit most from primary scleral buckling without vitrectomy, but lack adequate posterior segment ophthalmoscopic visualization to use standard techniques. CASE PRESENTATION: The authors describe a retinal reattachment technique utilizing endoscope-assisted visualization to perform a primary scleral buckle procedure for a 34yo female with Peters' Anomaly and a macula-sparing retinal detachment. Retinal reattachment was achieved with a single procedure and she remained stable with preservation of baseline visual acuity at 30 months follow-up. CONCLUSION: In cases where a primary scleral buckle procedure is the preferred retinal detachment repair technique but posterior segment visualization is limited, intraoperative fundus examination, cryotherapy administration, and scleral buckle positioning can be facilitated with intraocular endoscopy.

Extranodal Marginal Zone Lymphoma of Ocular Adnexa: Outcomes following Radiation Therapy.

AIM: The aim of this study was to report outcomes following radiation therapy in patients with biopsy-proven extranodal marginal zone lymphoma of the ocular adnexa and uvea. METHODS: Records from a single institution were retrospectively reviewed from January 1997 to December 2015. The mean follow-up duration was 38 months (range 0-194). Radiation therapy was administered to 77 eyes (60 patients); 57 of the 77 eyes (74%) were treated with radiation only (range 20-36 Gy, median 15 fractions). Radiation cataract, radiation retinopathy, and optic neuropathy assessments were performed on all eyes treated with radiation. RESULTS: 100% of the 47 patients treated with radiation therapy only had local control with an average dose of 26.5 Gy (median 25.2 [range 20-36] Gy; 150-200 cGy per fraction). Four patients lost 2 lines or more of vision after radiation. The most common complication of radiation therapy was cataract formation/progression in 19 eyes (25%). Radiation retinopathy was observed only in 1 patient (1%). CONCLUSION: Our results confirm that radiation therapy (median 25 Gy) for extranodal marginal zone lymphoma of the ocular adnexa is associated with high local control and low risk of visually significant complications.

Nucleophilic Aromatic Addition in Ionizing Environments: Observation and Analysis of New C-N Valence Bonds in Complexes between Naphthalene Radical Cation and Pyridine.

Radical organic ions can be stabilized by complexation with neutral organics via interactions that can resemble chemical bonds, but with much diminished bond energies. Those interactions are a key factor in cluster growth and polymerization reactions in ionizing environments such as regions of the interstellar medium and solar nebulae. Such radical cation complexes between naphthalene (Naph) and pyridine (Pyr) are characterized using mass-selected ion mobility experiments. The measured enthalpy of binding of the Naph+•(Pyr) heterodimer (20.9 kcal/mol) exceeds that of the Naph+•(Naph) homodimer (17.8 kcal/mol). The addition of 1-3 more pyridine molecules to the Naph+•(Pyr) heterodimer gives 10-11 kcal/mol increments in binding enthalpy. A rich array of Naph+•(Pyr) isomers are characterized by electronic structure calculations. The calculated Boltzmann distribution at 400 K yields an enthalpy of binding in reasonable agreement with experiment. The global minimum is a distonic cation formed by Pyr attack on Naph+• at the α-carbon, changing its hybridization from sp2 to distorted sp3. The measured collision cross section in helium for the Naph+•(Pyr) heterodimer of 84.9 ± 2.5 Å2 at 302 K agrees well with calculated angle-averaged cross sections (83.9-85.1 Å2 at 302 K) of the lowest energy distonic structures. A remarkable 16 kcal/mol increase in the binding energy between Naph+•(Pyr) and Bz+•(Pyr) (Bz is benzene) is understood by energy decomposition analysis. A similar increase in binding from Naph+•(NH3) to Naph+•(Pyr) (as well as between Bz+•(NH3) and Bz+•(Pyr)) is likewise rationalized.

Gas phase hydration of halogenated benzene cations. Is it hydrogen or halogen bonding?

Halogen bonding (XB) non-covalent interactions can be observed in compounds containing chlorine, bromine, or iodine which can form directed close contacts of the type R1-XY-R2, where the halogen X acts as a Lewis acid and Y can be any electron donor moiety including electron lone pairs on hetero atoms such as O and N, or π electrons in olefin double bonds and aromatic conjugated systems. In this work, we present the first evidence for the formation of ionic halogen bonds (IXBs) in the hydration of bromobenzene and iodobenzene radical cations in the gas phase. We present a combined thermochemical investigation using the mass-selected ion mobility (MSIM) technique and density functional theory (DFT) calculations of the stepwise hydration of the fluoro, chloro, bromo, and iodobenzene radical cations. The binding energy associated with the formation of an IXB in the hydration of the iodobenzene cation (11.2 kcal mol-1) is about 20% higher than the typical unconventional ionic hydrogen bond (IHB) of the CHδ+OH2 interaction. The formation of an IXB in the hydration of the iodobenzene cation involves a significant entropy loss (29 cal mol-1 K-1) resulting from the formation of a more ordered structure and a highly directional interaction between the oxygen lone pair of electrons of water and the electropositive region around the iodine atom of the iodobenzene cation. In comparison, the hydration of the fluorobenzene and chlorobenzene cations where IHBs are formed, -ΔS° = 18-21 cal mol-1 K-1 consistent with the formation of less ordered structures and loose interactions. The electrostatic potentials on the lowest energy structures of the hydrated halogenated benzene radical cations show clearly that the formation of an IXB is driven by a positively charged σ-hole on the external side of the halogen atom X along the C-X bond axis. The size of the σ-hole increases significantly in bromobenzene and iodobenzene radical cations which results in strong interaction potentials with the electron lone pairs of the oxygen atom of the water molecules and thus IXBs provide the most stable hydrated structures of the bromobenzene and iodobenzene radical cations. The results clearly distinguish the hydration behaviors resulting from the ionic hydrogen and halogen bonding interactions of fluorobenzene and iodobenzene cations, respectively, and establish the different bonding and structural features of the two interactions.

Observation of covalent and electrostatic bonds in nitrogen-containing polycyclic ions formed by gas phase reactions of the benzene radical cation with pyrimidine.

Polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic nitrogen heterocyclics (PANHs) are present in ionizing environments, including interstellar clouds and solar nebulae, where their ions can interact with neutral PAH and PANH molecules leading to the formation of a variety of complex organics including large N-containing ions. Herein, we report on the formation of a covalently-bonded (benzene·pyrimidine) radical cation dimer by the gas phase reaction of pyrimidine with the benzene radical cation at room temperature using the mass-selected ion mobility technique. No ligand exchange reactions with benzene and pyrimidine are observed indicating that the binding energy of the (benzene·pyrimidine)˙+ adduct is significantly higher than both the benzene dimer cation and the proton-bound pyrimidine dimer. The (benzene·pyrimidine)˙+ adduct shows thermal stability up to 541 K. Thermal dissociation of the (C6D6·C4H4N2)˙+ adduct at temperatures higher than 500 K produces C4H4N2D+ (m/z 82) suggesting the transfer of a D atom from the C6D6 moiety to the C4H4N2 moiety before the dissociation of the adduct. Mass-selected ion mobility of the (benzene·pyrimidine)˙+ dimer reveals the presence of two families of isomers formed by electron impact ionization of the neutral (benzene·pyrimidine) dimer. The slower mobility peak corresponds to a non-covalent family of isomers with larger collision cross sections (76.0 ± 1.8 Å2) and the faster peak is consistent with a family of covalent isomers with more compact structures and smaller collision cross sections (67.7 ± 2.2 Å2). The mobility measurements at 509 K show only one peak corresponding to the family of stable covalently bonded isomers characterized by smaller collision cross sections (66.9 ± 1.9 Å2 at 509 K). DFT calculations at the M06-2X/6-311++G** level show that the most stable (benzene·pyrimidine)˙+ isomer forms a covalent C-N bond with a binding energy of 49.7 kcal mol-1 and a calculated collision cross section of 69.2 Å2, in excellent agreement with the value obtained from the faster mobility peak of the (benzene·pyrimidine)˙+ dimer. Formation of a C-N covalent bond displaces a hydrogen atom from a C-H bond of the benzene cation which is transferred to the second pyrimidine nitrogen atom, thus preserving the pyrimidine π system and yielding the most stable (benzene·pyrimidine)˙+ isomer. The calculations also show less stable non-covalent electrostatically bonded perpendicular isomers of the (benzene·pyrimidine)˙+ dimer with a binding energy of 19 kcal mol-1 and a calculated collision cross section of 74.0-75.0 Å2 in excellent agreement with the value obtained from the slower mobility peak of the (benzene·pyrimidine)˙+ dimer.

Recurrent Conjunctival Myofibrosarcoma Managed With Triple Application of Episcleral Brachytherapy.

PURPOSE: To report a case of recurrent conjunctival myofibrosarcoma treated with wide surgical excision, cryotherapy, and triple sequential applications of episcleral brachytherapy. METHODS: A single case of recurrent conjunctival myofibrosarcoma. RESULTS: A 54-year-old man with a history of a renal transplant presented with a recurrent conjunctival tumor. Histopathologic diagnosis was established through immunohistochemistry. In total, 3 iodine radiation episcleral plaques were used over a period of 49 weeks. After cicatricial ectropion repair and cataract surgery, visual acuity was 20/20 at 4.5-year follow-up without evidence of recurrence or radiation retinopathy. CONCLUSIONS: Myofibrosarcoma is a rare mesenchymal tumor that can present as ocular surface tumor. Final histopathologic diagnosis can be challenging, and immunohistochemistry is important for evaluation. Myofibrosarcoma should be considered in the clinical differential diagnosis of atypical ocular surface lesions and the histopathologic differential diagnosis of ocular spindle neoplasms.

Surgical Drainage of Lymphangiectasia Haemorrhagica Conjunctivae.

PURPOSE: To report a case of nonresolving lymphangiectasia haemorrhagica conjunctivae (LHC) successfully treated with surgical drainage. METHODS: Retrospective case report. RESULTS: A 17-year-old white girl presented with a history of a large red lesion affecting her right eye. Approximately 1 year earlier, she had noticed a small painless "red spot" affecting the inferior aspect of the conjunctiva of her right eye. Three months before presentation, she noticed a sudden increase in the size of the lesion. There was no history of trauma, and she was not a contact lens wearer. Her medical history was remarkable for a remote seizure disorder which had been stable on levetiracetam. Magnetic resonance imaging/magnetic resonance angiography of the brain and orbits was unremarkable. Anterior segment fluorescein angiography did not show any flow in the lesion, indicating a lymphatic origin of channels. Surgical drainage of the lesion was performed while sparing the affected conjunctiva resulting in an excellent cosmetic outcome. Incisional biopsy confirmed the diagnosis of LHC. The patient remained free of recurrence 6 months after the procedure. CONCLUSIONS: Nonresolving LHC can be managed successfully with conjunctival sparing surgical drainage with an excellent cosmetic outcome.

Primary iris leiomyoma.

Intraocular leiomyomas are uncommon and usually occur in the ciliary body. Primary leiomyoma of the iris is both rare and a difficult diagnosis to make, given melanocytic tumors are more common and may be amelanotic. The somewhat controversial diagnosis of iris leiomyoma requires further confirmation by immunohistochemistry and electron microscopy. Herein, we describe a 58-year-old man with a 2-mm round translucent pink lesion of the iris. The tumor was excised by sector iridectomy. Immunohistochemistry showed positivity for both smooth muscle actin and desmin and negativity for S-100, HMB45, SOX10, MelanA, CD31, CD34, and h-caldesmon. Epstein-Barr virus-associated smooth muscle tumor was excluded by chromogenic in situ hybridization-Epstein-Barr virus-encoded RNA. Ultrastructural analysis showed cytoplasmic myofilaments with focal fusiform densities and micropinocytotic vesicles. Our review of previous literature confirmed the unusual nature of this tumor. Primary iris leiomyoma should be considered in the differential of an amelanotic S-100-immunonegative iris tumor.

Surgical removal of dystrophic calcification on a silicone intraocular lens in association with asteroid hyalosis.

We present a case of successful removal of late calcium deposition on the posterior surface of a silicone intraocular lens (IOL) optic in association with asteroid hyalosis using a surgical technique that included pars plana vitrectomy, a lighted pick, and a modified silicone-tipped cannula. The lighted pick provided the most efficient and complete removal of calcium deposits. Postoperatively, the dystrophic calcification was removed and the IOL optic was clear at 6 months follow-up. The patient's symptoms resolved and uncorrected distance visual acuity returned to 20/20. This method can be considered in patients with dystrophic calcification of a silicone IOL in association with asteroid hyalosis and might avoid the need for IOL exchange and its associated complications and uncertain refractive outcomes.

Optic Nerve Assessment Using 7-Tesla Magnetic Resonance Imaging.

PURPOSE: The purpose of this study was to correlate high-resolution magnetic resonance imaging (MRI) and histologic findings in a case of juxtapapillary choroidal melanoma with clinical evidence of optic nerve invasion. METHODS: With institutional review board approval, an enucleated globe with choroidal melanoma and optic nerve invasion was imaged using a 7-tesla MRI followed by histopathologic evaluation. RESULTS: Optical coherence tomography, B-scan ultrasonography, and 1.5-tesla MRI of the orbit (1-mm sections) could not detect optic disc invasion. Ex vivo, 7-tesla MRI detected optic nerve invasion, which correlated with histopathologic features. CONCLUSIONS: Our case demonstrates the potential to document the existence of optic nerve invasion in the presence of an intraocular tumor, a feature that has a major bearing on decision making, particularly for consideration of enucleation.

Unconventional CH(δ+)···N hydrogen bonding interactions in the stepwise solvation of the naphthalene radical cation by hydrogen cyanide and acetonitrile molecules.

Equilibrium thermochemical measurements using the mass-selected ion mobility (MSIM) technique have been utilized to investigate the binding energies and entropy changes of the stepwise association of hydrogen cyanide (HCN) and acetonitrile (CH3CN) molecules with the naphthalene radical cation (C10H8˙(+)) in the gas phase forming the C10H8˙(+)(HCN)n and C10H8˙(+)(CH3CN)n clusters with n = 1-3 and 1-5, respectively. The lowest energy structures of the C10H8˙(+)(HCN)n and C10H8˙(+)(CH3CN)n clusters for n = 1-2 have been calculated using the M062X and ω97XD methods within the 6-311+G** basis set, and for n = 1-6 using the B3LYP method within the 6-311++G** basis set. In both systems, the initial interaction occurs through unconventional CH(δ+)···N ionic hydrogen bonds between the hydrogen atoms of the naphthalene cation and the lone pair of electrons on the N atom of the HCN or the CH3CN molecule. The binding energy of CH3CN to the naphthalene cation (11 kcal mol(-1)) is larger than that of HCN (7 kcal mol(-1)) due to a stronger ion-dipole interaction resulting from the large dipole moment of CH3CN (3.9 D). On the other hand, HCN can form both unconventional hydrogen bonds with the hydrogen atoms of the naphthalene cation (CH(δ+)···NCH), and conventional linear hydrogen bonding chains involving HCN···HCN interactions among the associated HCN molecules. HCN molecules tend to form "externally solvated" structures with the naphthalene cation where the naphthalene ion is hydrogen bonded to the exterior of an HCN···HCN chain. For the C10H8˙(+)(CH3CN)n clusters, "internally solvated" structures are favored where the acetonitrile molecules are directly interacting with the naphthalene cation through CH(δ+)···N unconventional ionic hydrogen bonds. In both the C10H8˙(+)(HCN)n and C10H8˙(+)(CH3CN)n clusters, the sequential binding energy decreases stepwise to about 6-7 kcal mol(-1) by three HCN or CH3CN molecules, approaching the macroscopic enthalpy of vaporization of liquid HCN (6.0 kcal mol(-1)).

What Is the Structure of the Naphthalene-Benzene Heterodimer Radical Cation? Binding Energy, Charge Delocalization, and Unexpected Charge-Transfer Interaction in Stacked Dimer and Trimer Radical Cations.

The binding energy of the naphthalene(+•)(benzene) heterodimer cation has been determined to be 7.9 ± 1 kcal/mol for C10H8(+•)(C6H6) and 8.1 ± 1 kcal/mol for C10H8(+•)(C6D6) by equilibrium thermochemical measurements using the mass-selected drift cell technique. A second benzene molecule binds to the C10H8(+•)(C6D6) dimer with essentially the same energy (8.4 ± 1 kcal/mol), suggesting that the two benzene molecules are stacked on opposite sides of the naphthalene cation in the (C6D6)C10H8(+•)(C6D6) heterotrimer. The lowest-energy isomers of the C10H8(+•)(C6D6) and (C6D6)C10H8(+•)(C6D6) dimer and trimer calculated using the M11/cc-pVTZ method have parallel stacked structures with enthalpies of binding (-ΔH°) of 8.4 and 9.0 kcal/mol, respectively, in excellent agreement with the experimental values. The stacked face-to-face class of isomers is calculated to have substantial charge-transfer stabilization of about 45% of the total interaction energy despite the large difference between the ionization energies of benzene and naphthalene. Similarly, significant delocalization of the positive charge is found among all three fragments of the (C6D6)C10H8(+•)(C6D6) heterotrimer, thus leaving only 46% of the total charge on the central naphthalene moiety. This unexpectedly high charge-transfer component results in activating two benzene molecules in the naphthalene(+•)(benzene)2 heterotrimer cation to associate with a third benzene molecule at 219 K to form a benzene trimer cation and a neutral naphthalene molecule. The global minimum of the C10H8(+•)(C6H6)2 heterotrimer is found to be the one where the naphthalene cation is sandwiched between two benzene molecules. It is remarkable, and rather unusual, that the binding energy of the second benzene molecule is essentially the same as that of the first. This is attributed to the enhanced charge-transfer interaction in the stacked trimer radical cation.

Communication: Ion mobility of the radical cation dimers: (Naphthalene)2(+•) and naphthalene(+•)-benzene: Evidence for stacked sandwich and T-shape structures.

Dimer radical cations of aromatic and polycyclic aromatic molecules are good model systems for a fundamental understanding of photoconductivity and ferromagnetism in organic materials which depend on the degree of charge delocalization. The structures of the dimer radical cations are difficult to determine theoretically since the potential energy surface is often very flat with multiple shallow minima representing two major classes of isomers adopting the stacked parallel or the T-shape structure. We present experimental results, based on mass-selected ion mobility measurements, on the gas phase structures of the naphthalene(+⋅) ⋅ naphthalene homodimer and the naphthalene(+⋅) ⋅ benzene heterodimer radical cations at different temperatures. Ion mobility studies reveal a persistence of the stacked parallel structure of the naphthalene(+⋅) ⋅ naphthalene homodimer in the temperature range 230-300 K. On the other hand, the results reveal that the naphthalene(+⋅) ⋅ benzene heterodimer is able to exhibit both the stacked parallel and T-shape structural isomers depending on the experimental conditions. Exploitation of the unique structural motifs among charged homo- and heteroaromatic-aromatic interactions may lead to new opportunities for molecular design and recognition involving charged aromatic systems.