Aim. To evaluate the effect of preset elevated intraocular pressure (IOP) level during phacoemulsification on central retina artery and central retinal vein hemodynamics and to determine possible compensatory mechanisms of the ocular blood flow autoregulation in response to intraoperational IOP jump. Methods. This prospective study included 23 cataract patients without concomitant ocular vascular conditions (15 women and 8 men) aged from 62 to 83 years. The mean age was 72.5 5.7 years. In all patients, an intraoperational color duplex scanning in the regimens of color Doppler imaging and pulsed wave velocity imaging using ultrasound scanner Logiq S8 (GE). The blood flow was estimated in retrobulbar vessels: central retinal artery, central retinal vein with maximal systolic velocity, end-diastolic velocity of the blood flow, and resistance index (RI). The investigation was performed under IOP control, which was measured using Icare Pro tonometer, and under blood pressure control using patient monitoring system Draeger Vista 120. In the operating room, ocular blood flow was examined three times: immediately before surgery, straight after the surgical incision sealing at preset intraoperational IOP level, and after IOP normalization and repeated sealing of the corneal tunnel. Results. Under preset intraoperational IOP maintenance on 58.01 8.10 mm Hg level, there was a clinically significant (p 0.05) decrease of blood flow velocity in the central retinal artery. In 30.4% of cases, the blood flow velocity in the central retinal artery during diastolic phase was not registered. The flow velocity in central retinal vein did not change significantly, and did not depend on IOP level (p 0.05). Conclusions. At the 5560 mm Hg IOP level, in humans, compensatory blood flow autoregulation mechanisms in response to intraoperational IOP jumps are absent, up to complete blood flow stop in the central retinal artery at the diastolic phase, and this could be a risk factor for retinal ischemia.
In addition to the breadth of activity of antibacterial medications as well as to their pharmacokinetic and pharmacodynamic properties, their safety and bioavailability represent an important aspect. Currently, there is no consensus on fluoroquinolone toxicity. The aim of the present study was to compare the total cytotoxic effect on corneal epithelium and bioavailability of three antibacterial fluoroquinolone eye drops, registered in the Russian Federation: 1) Oftaquix™ (levofloxacin 5 mg/ml; preservative benzalkonium chloride (BAC) 0.05 mg/ml; produced by Santen Oy, Finland), hereafter “levofloxacin (original)”; 2) Signicef® (levofloxacin 5 mg/ml; preservative BAC 0.1 mg/ml; produced by Sentiss Pharma Pvt. Ltd., India), hereafter “levofloxacin (generic)”; 3) Vigamox® (moxifloxacin® 5 mg/ml; preservative-free; produced by Alcon Laboratories, Inc., USA) hereafter “moxifloxacin” - using in vivo methods and determining the possible effect of preservative presence (in different concentration) or of its absence on reaching the minimal threshold concentrations of the antibiotic in the anterior chamber fluid, using the high-yield liquid chromatography combined with mass-spectrometric detection. The study showed that tested antibacterial medications could exert a cytostatic effect on the corneal epithelium at in vivo conditions and differ in their cytotoxic potential. Benzalkonium chloride presence in Signicef in a concentration twice as high than that of the main medication (Oftaquix) causes a proven by confocal microscopy effect on the corneal epithelium, and this may influence the bioavailability of the medication.
Актуальность. Принципом факоэмульсификации является поддержание баланса ирригационно-аспирационных потоков. Баланс достигается за счет различных систем подачи жидкости, позволяющих хирургу задавать и поддерживать постоянный уровень ВГД во время операции. Вопрос об оптимальном безопасном уровне ВГД во время вмешательства на сегодняшний день остается открытым. Цель. Оценить влияние повышенного уровня интраоперационного офтальмотонуса на скорость кровотока в центральной артерии, вене сетчатки, и задних коротких цилиарных артериях. Материал и методы. В исследование было включено 29 пациентов с начальной катарактой. Факоэмульсификация выполнялась на приборе Alcon Centurion vision system на предустановленном интраоперационном уровне ВГД 60 мм.рт.ст. Скорость кровотока измеряли путем дуплексного сканирования в режиме ЦДК трёхкратно: до вскрытия глазного яблока, интраоперационно на уровне ВГД (58.77±8.28 мм.рт. ст) и сразу после герметизации доступа и нормализации ВГД. Каждое измерение сопровождалось контролем ВГД и АД. Результаты. При значении уровня ВГД 58.77±8.28 мм.рт. ст в ЦАС и ЗКЦА отмечалось статистически достоверное снижение максимальной систолической скорости кровотока. С 12,62±3,07 до 9,93±2,77 см/с и снижение конечной диастолической скорости кровотока с 3,94±1,09 до 1,79±1,64 см/с. В 11 из 29 (37,9%) случаев скорость кровотока в ЦАС в диастолическую фазу не регистрировалась. Максимальная систолическая скорость кровотока в ЗКЦЛА снизилась на 22%. Конечная диастолическая снизилась с 5,11±1,83 до 2,97±1,27 см/с. Аналогично, максимальная систолическая скорость кровотока с медиальной стороны упала с 12,37±2,74 до 9,50±1,68 см/с, а конечная диастолическая скорость кровотока снизилась с 4,54±1,35 до 2,73± 0,91 см/с. Скорость кровотока в ЦВС менялась незначительно и не зависела от уровня ВГД. Выводы. На уровне ВГД 58.77±8.28 мм. рт. ст. у человека отсутствуют компенсаторные механизмы ауторегуляции глазного кровотока в ответ на резкое повышение интраоперационного уровня ВГД, вплоть до полного прекращения кровотока в ЦАС в диастолическую фазу, что может приводить к ишемии тканей сетчатки.
BACKGROUND: The cutting action of a femtosecond laser (FS-laser) on the corneal tissue is performed using a photodestructive effect. FS-laser technology is used in many different areas of corneal surgery, and studying this effect is an actual issue. AIM: To evaluate the surface of the corneal incision created by a FS-laser (experimental study). MATERIALS AND METHODS: 20 porcine eyes were divided into two groups (FS-laser and keratome). The corneal tissue surface in the area of contact between two lips of the incision was visualized by electron microscopy. RESULTS: In all cases, we received a full-thickness incisions through the cornea. Images obtained by electron microscopy showed regular surface, no signs of thermal or mechanical damage to the corneal structure. CONCLUSIONS: The FS-laser is used as a microscopic scalpel in surgery. The precision cutting process is performed by mechanical forces generated by photodestruction by expanding cavitation bubbles.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.