Factors Affecting Optic Nerve Sheath Diameter and Visual Acuity Changes in Adult Patients Undergoing Prone Spine Surgery: A Prospective Observational Study
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 发起方
- 入组人数
- 65
- 试验地点
- 1
- 主要终点
- Change in ultrasonographic optic nerve sheath diameter (mm)
研究概览
简要总结
The prone position in spinal surgery can alter intracranial pressure and optic nerve sheath diameter (ONSD) and potentially lead to visual complications. This prospective observational study aimed to identify factors influencing ultrasonographic ONSD changes and visual acuity in patients undergoing spinal surgery.
详细描述
During spine surgery, many patients are positioned face-down (prone position) for several hours. This position may influence blood flow to the head and increase pressure around the brain and eyes. One structure that can reflect these pressure changes is the optic nerve sheath, which surrounds the optic nerve at the back of the eye. When the pressure inside the skull rises, the optic nerve sheath may become wider. This change can be measured non-invasively using ultrasound and is referred to as optic nerve sheath diameter (ONSD).
This prospective observational study will evaluate whether ONSD changes occur in adult patients undergoing prone-position spine surgery and whether these changes are related to temporary alterations in vision. Visual acuity will be evaluated using a standard Snellen chart before surgery and on the first postoperative day to detect any change in vision after the procedure.
Ultrasound ONSD measurements will be performed in three stages: before the patient is placed in the prone position, shortly after the prone position is established, and at the end of the surgery while still in the same position. Clinical variables such as blood pressure, carbon dioxide levels, ventilation parameters, anesthesia technique, the use of a pinned head holder, and patient characteristics will also be recorded. By comparing these variables with ONSD and visual outcomes, the study aims to identify whether specific surgical or physiological factors contribute to increased optic nerve sheath width or temporary vision disturbances.
This research does not involve any experimental drug or device. All measurements are part of routine safe monitoring techniques used to assess patients' condition during surgery. The goal of this study is to help better understand factors that may increase the risk of eye-related complications during prone spine surgery and to contribute to safer surgical practices.
研究设计
- 研究类型
- Observational
- 观察模型
- Cohort
- 时间视角
- Prospective
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Age ≥ 18 years
- •Scheduled to undergo elective spine surgery in the prone position
- •American Society of Anesthesiologists (ASA) physical status I-III
- •Preoperative visual acuity measurable using a Snellen chart
排除标准
- •Preexisting ophthalmologic diseases affecting optic nerve or visual acuity (e.g., glaucoma, optic neuropathy, diabetic retinopathy)
- •Previous eye trauma or history of orbital surgery
- •Inability to obtain reliable ultrasonographic ONSD measurements (e.g., orbital deformity, ocular infection)
研究组 & 干预措施
Prone Spine Surgery Cohort
Adults undergoing prone-position spine surgery, evaluated with ultrasound ONSD measurements and visual acuity testing.
结局指标
主要结局
Change in ultrasonographic optic nerve sheath diameter (mm)
时间窗: Baseline (preoperative, supine), after prone positioning (15 minutes after positioning), and at the end of surgery (intraoperative, before repositioning to supine).
Optic nerve sheath diameter (ONSD) will be measured bilaterally using standardized transorbital ultrasonography with a high-frequency linear probe (6-13 MHz). Measurements will be obtained 3 mm posterior to the globe, in accordance with established sonographic guidelines. For each eye, three measurements will be recorded, and the mean value will be calculated. The average of both eyes will be used for statistical analysis. The primary outcome will be the absolute change in ONSD (ΔONSD, mm) between baseline and intraoperative prone measurements.
次要结局
- Change in visual acuity (logMAR)(Baseline (preoperative) and postoperative day 1.)
- Correlation between change in ONSD and intraoperative end-tidal carbon dioxide (EtCO₂)(Intraoperative period: baseline (supine), after prone positioning (15 minutes), and at the end of surgery.)
- Difference in ONSD change between pinned head holder and non-pinned positioning(ntraoperative period: baseline (supine), after prone positioning (15 minutes), and at the end of surgery.)
- Association between postoperative visual acuity change and intraoperative ONSD change(Baseline (preoperative) and postoperative day 1.)
- Correlation between change in ONSD and intraoperative mean arterial pressure (MAP)(Intraoperative period: baseline (supine), after prone positioning (15 minutes), and at the end of surgery.)
- Correlation between change in ONSD and intraoperative arterial partial pressure of carbon dioxide (PaCO₂)(Intraoperative period: baseline (supine), after prone positioning (15 minutes), and at the end of surgery.)
- Correlation between change in ONSD and intraoperative arterial partial pressure of oxygen (PaO₂)(Time Frame: Intraoperative period: baseline (supine), after prone positioning (15 minutes), and at the end of surgery.)
- Correlation between change in ONSD and intraoperative positive end-expiratory pressure (PEEP)(Intraoperative period: baseline (supine), after prone positioning (15 minutes), and at the end of surgery.)
研究者
Begüm Ramakan, MD
Resident Physician in Anesthesiology and Reanimation
Istanbul University - Cerrahpasa