Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA; Department of Neurology, University of California, Los Angeles, Los Angeles, CA, USA; Neuroscience Interdepartmental Program, University of California, Los Angeles, Los Angeles, CA, USA; Biomedical Engineering Interdepartmental Program, University of California, Los Angeles, Los Angeles, CA, USA; David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA, USA; David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
Am J Ophthalmol. 2021 Jan;221:137-146. doi: 10.1016/j.ajo.2020.09.002. Epub 2020 Sep 9.
Magnetic resonance imaging (MRI) of extraocular muscle function was used to evaluate the role of newly recognized mechanisms underlying compensation of large heterophoria by vertical fusional vergence (VFV).
Prospective case series.
At one academic center, 8 adults with large hyperphoria and supernormal VFV underwent MRI during monocular and binocular fixation of a centered, near target. Contractility of the rectus and superior oblique (SO) extraocular muscles in hypertropic and hypotropic eyes was determined from changes in posterior partial volume (PPV).
Five of 8 patients could sustain binocular fusion in the scanner. In those patients, VFV corrected approximately 5-degree misalignment, approximately 5-fold greater than normal VFV. Vertical strabismus was compensated mainly by significant contractility of the lateral more than the medial compartment of the inferior rectus (IR) in both eyes (P < .005). The superior rectus (SR) and inferior oblique muscles had no significant contractile contribution, although the hypotropic SO relaxed significantly. The IR lateral compartment and SR medial compartment significantly co-relaxed when binocular fusion was attained from monocular target fixation (P < .01).
Although VFV protects patients from small muscle imbalances over the lifespan, even enhanced VFV may be inadequate to avert diplopia. Compensation of hyperphoria by VFV is accomplished mainly by IR muscle relaxation in the hypotropic eye, principally in its selectively innervated lateral compartment, whereas the SO contributes little. Fusion involves compartmentally selective co-relaxation in hypotropic eye vertical rectus muscles. Taken together, these overall findings suggest a physiologic basis to prefer therapeutic surgical weakening of the medial IR in the hypotropic eye.
眼外肌功能磁共振成像（MRI）用于评估新发现的机制在大隐斜视的垂直融合性聚散（VFV）代偿中的作用。
前瞻性病例系列。
在一个学术中心，8 名大斜视伴超 VFV 的成年人在单眼和双眼注视中心近目标时接受 MRI 检查。通过后部分容积（PPV）的变化确定外直肌和上斜肌（SO）在远视和低矫眼中的收缩性。
8 名患者中有 5 名可在扫描仪中维持双眼融合。在这些患者中，VFV 纠正了大约 5 度的斜视，大约是正常 VFV 的 5 倍。垂直斜视主要通过下直肌（IR）外侧比内侧隔间的显著收缩来补偿，双眼均如此（P<.005）。上直肌（SR）和下斜肌没有明显的收缩贡献，尽管低矫的 SO 明显松弛。当从单眼目标注视获得双眼融合时，IR 外侧隔间和 SR 内侧隔间显著共同松弛（P<.01）。
尽管 VFV 在患者的一生中保护其免受小肌肉失衡的影响，但即使增强的 VFV 也可能不足以避免复视。VFV 补偿大斜视主要是通过低矫眼 IR 肌肉松弛来实现的，主要是其选择性支配的外侧隔间，而 SO 贡献不大。融合涉及低矫眼垂直直肌隔间选择性共同松弛。总的来说，这些发现表明，在低矫眼中，治疗性手术减弱内侧 IR 的方法具有生理基础。
