Shin Hyun Jin, Lee Sang Jae, Oh Chung-Sik, Kang Hyunkyoo
Department of Ophthalmology, Research Institute of Medical Science, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Republic of Korea; Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital, Houston, TX, USA.
School of Medicine, Konkuk University, Seoul, Republic of Korea.
J Biomech. 2020 Aug 26;109:109955. doi: 10.1016/j.jbiomech.2020.109955. Epub 2020 Jul 15.
Accurate knowledge of extraocular muscle (EOM) tension is important for the diagnosis of and surgical planning for strabismus, such as choosing which eye to operate or determining the amount of muscle displacement. Previous evaluations of passive EOM tension have relied extensively on the experience and skill of ophthalmic surgeons, who generally perform such evaluations by gripping the eyeball and then pushing and pulling it. This methodology, named the forced duction test, has the significant limitation that the tension is felt subjectively via the forceps, with the results therefore not being quantifiable. Previous quantitative analyses have utilized several different types of equipment with implanted force transducers or have involved connecting the muscle tendon to a strain gauge. However, the associated equipment setups and recording systems are highly complex and rarely used outside research settings. This situation prompted the present study to develop a novel compact, quantifiable and clinically applicable device for measuring the passive tension in human EOMs for use in clinical practice. The device employs locking forceps and a tilting sensor to rule out effects of the gripping force and to compensate for changes in the force due to tilting, which improves the measurement accuracy. The performance of the device was investigated in 60 eyes of 30 consecutive anaesthetized patients immediately prior to ophthalmic surgery. The results showed that the measured EOM tension in each rectus muscles agreed with previous findings: 48.3 ± 14.5 g (0.82 ± 0.28 g/deg, mean ± SD) for the lateral rectus, 45.6 ± 13.2 g (0.82 ± 0.23 g/deg) for the medial rectus, 48.6 ± 14.7 g (0.71 ± 0.21 g/deg) for the inferior rectus and 53.4 ± 13.7 g (0.77 ± 0.25 g/deg) for the superior rectus.
准确了解眼外肌（EOM）张力对于斜视的诊断和手术规划至关重要，例如选择手术眼或确定肌肉移位量。以往对被动眼外肌张力的评估很大程度上依赖眼科医生的经验和技能，他们通常通过抓住眼球然后推拉来进行此类评估。这种方法称为强迫牵引试验，有一个重大局限性，即张力是通过镊子主观感受的，因此结果无法量化。以往的定量分析使用了几种不同类型的植入力传感器设备，或者涉及将肌腱连接到应变仪。然而，相关的设备设置和记录系统非常复杂，很少在研究环境之外使用。这种情况促使本研究开发一种新颖的、紧凑的、可量化的且适用于临床的装置，用于测量人类眼外肌的被动张力，以用于临床实践。该装置采用锁定镊子和倾斜传感器来排除夹持力的影响，并补偿由于倾斜引起的力的变化，从而提高测量精度。在眼科手术即将开始前，对30例连续麻醉患者的60只眼睛进行了该装置性能的研究。结果表明，每条直肌的测量眼外肌张力与先前的研究结果一致：外直肌为48.3±14.5克（0.82±0.28克/度，平均值±标准差），内直肌为45.6±13.2克（0.82±0.23克/度），下直肌为48.6±14.7克（0.71±0.21克/度），上直肌为53.4±13.7克（0.77±0.25克/度）。
