School of Optometry, Indiana University, Bloomington, Indiana, USA.
Department of Psychology, Northeastern University, Boston, Massachusetts, USA.
Ophthalmic Physiol Opt. 2023 Jul;43(4):598-614. doi: 10.1111/opo.13093. Epub 2023 Jan 24.
Individuals with different types of intermittent exotropia (IXT) may use neurally coupled accommodation and vergence responses differently from those without exotropia to achieve eye alignment. This study examined the relationship between simultaneously recorded accommodation and vergence responses in children and young adults with a range of types of IXT while aligned and deviated.
Responses of 29 participants with IXT (4-31 years) and 24 age-matched controls were recorded using simultaneous eye-tracking and eccentric photorefraction while they watched a movie in binocular or monocular viewing at varying viewing distances. Gradient response AC/A ratios and fusional vergence ranges were also assessed. Eight participants had divergence or pseudo-divergence excess type IXT, 5 had convergence insufficiency and 16 had basic IXT.
Control and IXT participants accommodated similarly both in monocular and binocular-aligned conditions to visual targets at 80 and 33 cm. When deviated in binocular viewing, most participants with IXT exhibited changes in accommodation <0.5D relative to alignment. Gradient response AC/A ratios were similar for control [0.56 MA/D (IQR: 0.51 MA/D)] and IXT participants [0.42 MA/D (0.54 MA/D); p = 0.60]. IXT participants showed larger vergence to accommodation ratios with changes from distance to near fixation [1.19 MA/D (1.45 MA/D)] than control participants [0.78 MA/D (0.60 MA/D); p = 0.02], especially among IXT participants with divergence or pseudo-divergence excess. Participants with IXT exhibited typical fusional divergence ranges beyond their dissociated position [8.86 Δ (7.10 Δ)] and typical fusional convergence ranges from alignment [18 Δ (15.75 Δ)].
This study suggests that control of IXT is typically neither driven by accommodative convergence alone nor associated with over-accommodation secondary to fusional convergence efforts. These simultaneous measurements confirmed that proximal vergence contributed significantly to IXT control, particularly for divergence or pseudo-divergence excess type IXT. For IXT participants in this study, achieving eye alignment did not conflict with having clear vision.
不同类型间歇性外斜视（IXT）患者在实现眼位正位时，其神经相关调节和聚散反应可能与无斜视患者不同。本研究旨在观察和分析不同类型间歇性外斜视患者在双眼和单眼注视时调节和聚散同步记录的反应，评估斜视患者的神经调节和聚散功能。
使用双眼视眼动追踪和偏心视网膜验光技术，在 29 名间歇性外斜视患者（4-31 岁）和 24 名年龄匹配的对照组儿童和青少年观看电影时，记录他们在双眼和单眼不同视距下的调节和聚散反应。同时评估梯度性调节性集合/调节（AC/A）比率和融合性聚散范围。8 名患者为分开性/假性分开性外斜视，5 名患者为集合不足，16 名患者为基本型间歇性外斜视。
在 80cm 和 33cm 视觉目标下，无论是在双眼正位还是单眼正位时，对照组和间歇性外斜视组的调节反应都相似。在双眼注视时偏离目标时，大多数斜视患者的调节变化小于 0.5D。对照组的梯度性 AC/A 比率为 0.56（IQR：0.51），斜视组为 0.42（IQR：0.54）；p=0.60。与对照组相比，间歇性外斜视患者在从远距离注视转为近距离注视时的调节性集合/调节比值更大[1.19（1.45）]，差异有统计学意义（p=0.02），尤其是在分开性/假性分开性外斜视患者中。斜视患者在其分离位置以外表现出典型的融合性散开范围[8.86Δ（7.10Δ）]，在注视正位时表现出典型的融合性集合范围[18Δ（15.75Δ）]。
本研究表明，间歇性外斜视的控制既不是单纯的调节性集合驱动，也不是融合性集合努力导致的过度调节。这些同步测量结果证实，近端聚散在间歇性外斜视的控制中起着重要作用，特别是对分开性/假性分开性外斜视患者。对于本研究中的间歇性外斜视患者，实现眼位正位并不与保持清晰视力相冲突。
