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A CASE OF RETINAL ATHEROSCLEROTIC OXALOSIS DUE TO HYPEROXALURIA IN A PATIENT WITH SHORT GUT SYNDROME.

To describe a severe case of crystalline retinopathy secondary to hyperoxaluria from short gut syndrome. Case report. A 62-year-old Caucasian woman with short gut syndrome and end-stage renal disease from renal oxalosis presented with chronic bilateral vision loss. She had previously been treated for presumed occlusive vasculitis. Visual acuity on initial examination was 20/400 right eye and 20/100 left eye with an afferent pupillary defect of the right eye. Examination revealed attenuated retinal vasculature and diffuse crystalline infiltration of retinal arterial lumina and throughout the retinas bilaterally. Optical coherence tomography revealed inner retinal atrophy with crystalline deposition in the inner retinal layers. Fluorescein angiography demonstrated delayed vascular filling and dropout consistent with severe ischemic vasculopathy. It was concluded that the short-gut syndrome led to overabsorption of oxalate with subsequent hyperoxaluria leading to retinal atherosclerotic oxalosis. Retinal calcium oxalate deposits due to hyperoxaluria have been previously noted; however, this degree of severe retinal vascular infiltration has not been described. Our patient was receiving hemodialysis, which is associated with high rebound increases in systemic oxalate concentrations. It is important to keep hyperoxaluria in mind as a potential cause of retinopathy in patients with end-stage renal disease presenting with vision loss.

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Multispecialty Management of Metastatic Colon Adenocarcinoma Involving the Extraocular Muscles: Primary Excision and Simultaneous Treatment of Strabismus With a Review of the Literature.

Metastatic colon adenocarcinoma involving the extraocular muscles is extremely rare. It usually develops following the diagnosis of the systemic disease and therefore, management and treatment require a multispecialty approach. Within this manuscript, we provide a summary of cases of orbital metastasis secondary to colon cancer. We further discuss a detailed case of a 42-year-old male patient who developed recent-onset diplopia in the left gaze. Orbital CT imaging showed a localized, well-circumscribed enlargement of the right medial rectus muscle. The biopsy of the right medial rectus showed adenocarcinoma originating from the gastrointestinal system. Further workup revealed colon adenocarcinoma with multiple metastatic sites. The patient started systemic chemotherapy. After 2 months of chemotherapy (5-fluouracil, oxaliplatin, irinotecan, and leucovorin), all systemic metastatic sites regressed; however, his medial rectus muscle continued to grow, causing compressive optic neuropathy. The patient underwent excisional biopsy of the right medial rectus muscle with simultaneous repair of the strabismus with transposition of superior and inferior recti muscles. He continued with systemic chemotherapy. Follow up in 1 year revealed no local orbital tumor recurrence with excellent visual acuity and no diplopia in primary gaze.

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Diabetic Retinopathy and Regulation of Mitochondrial Glutathione-Glutathione Peroxidase Axis in Hyperhomocysteinemia.

Diabetic patients have elevated homocysteine levels, and hyperhomocysteinemia is shown to exacerbate mitochondrial damage, which plays a central role in diabetic retinopathy. Glutathione peroxidases (GPx) catalyze hydrogen peroxide (H2O2) reduction using glutathione (GSH) as a cofactor. GSH and GPx are mainly cytosolic but are also present in the mitochondria to neutralize H2O2 produced by superoxide dismutase, and in diabetes, they are downregulated. Hyperhomocysteinemia also disrupts the balance between S-adenosyl-L-homocysteine and S-adenosylmethionine (SAM); SAM is also a methyl donor for DNA methylation. The aim of this study was to investigate the role of homocysteine in mitochondrial GSH-GPx1 regulation in diabetic retinopathy. Human retinal endothelial cells in 20 mM D-glucose + high homocysteine were analyzed for ROS, GSH and GPx in the mitochondria, and SAM levels and GPx1 promoter DNA methylation were also studied (5-methylcytosine and MS-PCR). The results were confirmed in the retina from streptozotocin-induced hyperhomocysteinemic (cystathionine-β-synthase-deficient) diabetic mice. High homocysteine exacerbated the glucose-induced decrease in GSH levels and GPx activity in the mitochondria and the downregulation of GPx1 transcripts and further increased SAM levels and GPx1 promoter DNA methylation. Similar results were obtained in a hyperglycemic-hyperhomocysteinemic mouse model. Thus, elevated homocysteine in diabetes hypermethylates GPx1 promoter, thus decreasing the mitochondrial GPx/GSH pool and exacerbating mitochondrial damage. Modulating hyperhomocysteinemia could be a potential therapeutic avenue to target mitochondrial dysfunction in diabetic retinopathy.

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Glaucoma Surgery Shifts Among Medicare Beneficiaries After 2022 Reimbursement Changes in the United States.

This study revealed the best-estimated surgical procedural counts for 2021 and 2022 and suggests a direct influence of coding and reimbursement changes on surgical device selection. To analyze utilization rates of glaucoma surgeries and minimally invasive (microinvasive) glaucoma surgery among US Medicare beneficiaries between 2021 and 2022. Retrospective comparative analysis of 68,118 unique patients. National claims data from a 5% sample of all Medicare beneficiaries were utilized to compare glaucoma procedure counts between the first quarter of 2021 and the first quarter of 2022. Duplicate claims were excluded, and 50 modifiers were counted as 2 distinct procedures. A multiplier was applied to estimate annual utilization for the entire Medicare population. χ 2 analysis was employed to compare categorical data from the 2 time periods. Current Procedural Terminology codes for angle-based stenting decreased by an estimated 20,960 procedures between 2021 and 2022 (28.60%). Goniotomy increased by an estimated 11,680 procedures (66.97%) and canaloplasty increased by an estimated 6640 procedures (47.43%). Glaucoma surgeries decreased by an estimated 5760 procedures (4.25%) despite an increase of cataract surgery by 234,960 procedures (15.63%), an increase in YAG capsulotomy by 19,280 procedures (3.31%), and an increase in intravitreal injections by 146,320 procedures (3.86%). Despite overall surgical volume increases among the ophthalmology procedures, angle-based stenting utilization decreased significantly with an accompanying trend change following the coding and reimbursement changes implemented in January 2022. Of the minimally invasive (microinvasive) glaucoma surgery procedures, goniotomy and canaloplasty counts increased the most between these periods. Trabeculectomy and glaucoma drainage device procedures continued to decrease, following well-established trends. Future studies are warranted to examine how these shifts in utilization may impact patient care outcomes.

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