Sensitive Metal-Semiconductor Nanothermocouple Fabricated by FIB to Investigate Laser Beams with Nanometer Spatial Resolution

The focused ion beam (FIB) technique was used to fabricate a nanothermocouple (with a 90 nm wide nanojunction) based on a metal–semiconductor (Pt–Si) structure, which showed a sensitivity up to 10 times larger (with Seebeck coefficient up to 140 µV/K) than typical metal–metal nanothermocouples. In contrast to the fabrication of nanothermocouples which requires a high-tech semiconductor manufacturing line with sophisticated fabrication techniques, environment, and advanced equipment, FIB systems are available in many research laboratories without the need for a high-tech environment, and the described processing is performed relatively quickly by a single operator. The linear response of the manufactured nanothermocouple enabled sensitive measurements even with small changes of temperature when heated with a stream of hot air. A nonlinear response of the nanothermocouple (up to 83.85 mV) was observed during the exposition to an argon-laser beam with a high optical power density (up to 17.4 Wcm−2), which was also used for the laser annealing of metal–semiconductor interfaces. The analysis of the results implies the application of such nanothermocouples, especially for the characterization of laser beams with nanometer spatial resolution. Improvements of the FIB processing should lead to an even higher Seebeck coefficient of the nanothermocouples; e.g., in case of the availability of other suitable metal sources (e.g., Cr).

Multinucleate Cell Angiohistiocytoma: A Case Report and Unique Treatment Consideration

Introduction: Multinucleate cell angiohistiocytoma (MCAH) is a benign, yet exceedingly rare vascular and firbiohistiocytic proliferation. The lesions are typically asymptomatic and are commonly cosmetically displeasing to patients. 1 Previous reports have demonstrated success in treating MCAH with fractional ablative CO2 laser, argon laser, pulsed dye laser, and KTP lasers. 3 The scarcity of reported cases may suggest that the lesion is commonly misdiagnosed, and we report this case to highlight the characteristic features of MCAH with successful treatment with Neodymium YAG laser. Case Presentation: A 64-year- old female presented to our clinic with a 1- month history of multiple erythematous to violaceous lesions on her bilateral hands. The lesions were asymptomatic, but cosmetically displeasing for the patient. Past medical history and family history was noncontributory. Examination revealed several 2-6 mm well- circumscribed, erythematous, indurated smooth papules on the bilateral dorsal and in the second web space of the left hand. Shave biopsy of the lesions were consistent with MCAH. She was initially treated with topical steroids twice daily for 2 weeks, with no improvement. The patient received 3 treatments with Neodymium YAG, 4 weeks apart. This treatment was discontinued after 3 sessions due to the dramatic visible improvements in regards to induration and discoloration of the lesions. Discussion: MCAH is an extremely uncommon lesion, diagnosis is made on the basis of clinical examination, histopathologic and immunohistochemical analysis of the lesions. This case illustrates diagnosis and successful treatment of MCAH with Neodymium YAG and offers a unique treatment consideration for patients.

The Therapeutic Predicament of Branch Retinal Vein Occlusion in uncontrolled Hypertension in Pakistan

Around the globe, hypertension is a silent pandemic. After diabetic retinopathies, hypertensive retinal vascular diseases are one of the most prevalent. In Pakistan, diagnostic investigations due to their cost are not done on regular screening basis as the financial burden of management is a point at issue. Thus, such conditions can often go undetected or therapeutically compromised. Here is a case of unilateral ischemic branch retinal vein occlusion in a 48-year-old male with a history of uncontrolled hypertension and diabetes. Additional laboratory investigations were carried out including complete lipid profile, serum urea and creatinine levels. Fundus fluorescein angiography and optical coherence tomography was done. The patient was managed on anti-VEGF injections and Argon Laser. Follow-up along with a multi-disciplinary management approach is essential for the best possible prognosis. Keywords: hypertension, central retinal vein occlusion (CRVO), branch retinal vein occlusion (BRVO)

Loss of Vision after Laser Peripheral Iridotomy: A Case Report

Laser Peripheral Iridotomy (LPI) is a common laser procedure carried out in patients with narrow or occluded irido-corneal angles at risk of developing angle closure glaucoma. Nd-YAG and Argon laser are used sequentially in our local population to create an iridotomy. Posterior segment complications are rare after this procedure and generally can occur due to direct laser induced damage. We report a 44-year old patient, who had LPI performed on his both eyes. Post laser patient complained of reduced vision in his left eye and was evaluated in our glaucoma clinic. On examination, his vision was 20/25 unaided in his right eye and 20/60 in his left eye with no further improvement. Optical coherence tomography (OCT) revealed presence of cystoid macular edema (CME) in his left eye responsible for his reduced vision. Key Words: Laser Peripheral Iridotomy, Cystoid Macular Edema, Argon Laser.

How ‘eye’ helped in von Hippel-Lindau syndrome

Background: Von Hippel-Lindau syndrome is a rare autosomal dominantly inherited multisystemic oncologic syndrome, presenting predominantly with angiomatosis in embryologically similar neurologic tissue such as retina, cerebellum and adrenals. Retinal hemangioblastomas are the hallmark ophthalmic finding. In this case report, we describe the importance of timely diagnosis, thorough systemic examination and treatment of bilaterally asymmetrical retinal hemangioblastomas in a young adult male. Case presentation: A 31-year-old male presented with painless diminution of vision in both eyes, associated with eyestrain and headache. Multiple asymmetric retinal lesions and dilated feeder vessels were noted on ophthalmoscopic examination and confirmed by fluorescein angiography to be retinal hemangioblastomas. Comprehensive systemic examination revealed cerebellar hemangioblastomas and multiple pancreatic and renal cysts. Treatment of retinal lesions was done by combination therapy of argon laser photocoagulation and cryopexy, which lead to a good visual outcome. Subsequently, neurosurgical resection of cerebellar hemangioblastoma proved to be lifesaving for the patient. Conclusion: RHBs are the earliest, easiest and the most frequently detected manifestation of VHL. Identification of ocular manifestations play a pivotal role in early diagnosis and timely intervention in VHL syndrome, thereby significantly reducing associated morbidity and mortality. Therefore, an ophthalmologist’s role is crucial in the management of these potentially deadly tumours.

Argon laser photocoagulation for treatment of presumed trematode-induced granulomatous anterior uveitis in children

Background/AimsTo assess the safety and efficacy of argon laser photocoagulation as a new modality for the treatment of presumed trematode-induced granulomatous anterior uveitis (PTGAU) in children.MethodsForty-eight eyes of 48 children with PTGAU with pearl-like nodule(s) in the anterior chamber were included in this prospective non-randomised controlled clinical trial. The patients were divided into two groups: those in Group A (23 eyes) were treated with one session of argon laser applied to the anterior chamber nodules and those in Group B (25 eyes) received medical treatment in the form of topical steroid and cycloplegic eye drops with trans-septal triamcinolone injections. All cases were followed up for 3 months with measurement of visual acuity (VA), assessment of the anterior chamber reaction and measurement of the pearl-like nodule size.ResultsIn Group A, 22 eyes (95.65%) showed regression of the pearl-like nodules with resolution of the anterior chamber reaction (flare and cells) and improvement in visual acuity from 0.52±0.12 to 0.06±0.08 logMAR (p<0.001). Such improvement was maintained within the 3-month follow-up period. In Group B, 23 eyes (92%) showed initial regression of the granulomas, which was maintained in only 14 eyes (56%),with nine eyes experiencing recurrence after 3 months of follow-up.ConclusionArgon laser photocoagulation is a safe and effective novel treatment for PTGAU with pearl-like nodules in the anterior chamber in children. Larger studies with longer follow-up periods are needed to confirm these results.