Serra Alessandro, Dell'Osso Louis F, Jacobs Jonathan B, Burnstine Robert A
Daroff-Dell'Osso Ocular Motility Laboratory, Louis Stokes Cleveland Veterans Affairs Medical Center, and Department of Neurology, Case Western University and University Hospitals of Cleveland, OH 44106, USA.
Invest Ophthalmol Vis Sci. 2006 Jun;47(6):2451-60. doi: 10.1167/iovs.05-1320.
To investigate the convergence-induced waveform and high-acuity-field improvements resulting from different therapies in two subjects with infantile nystagmus (IN) that was damped by convergence and to report a new finding in one of the subjects.
Infrared reflection was used to measure eye movements during fixation of targets at different gaze and convergence angles and the expanded nystagmus acuity function (NAFX) to evaluate the IN waveform's foveation quality at all fixation points.
Recordings demonstrated that, at far, both subjects exhibited classic nulls (high NAFX values) with NAFX reduction at gaze angles lateral to the null. S1 was treated with prisms and S2 with surgery. When converged at near or at far with base-out prisms (S1) or after bimedial recession and bilateral tenotomy surgery (S2), NAFX was higher at both the null and lateral gaze angles; the null region was broadened. The longest foveation domain (gaze angles where the NAFX is within 10% of its peak) at near was three times wider than at far for S1 and two times wider after than before surgery for S2. The therapeutic improvement domain (gaze angles where the posttherapy NAFX is higher than pretherapy) was even broader. At fixed gaze angles in the central 20 degrees of gaze, S1's NAFX variation with vergence exhibited hysteresis, higher during divergence than convergence; S2 exhibited no hysteresis after surgery.
Damping IN by means of convergence, induced either surgically or with prisms, broadened the range of gaze angles with higher foveation quality, mimicking the null-broadening effects of tenotomy. The discovery of vergence hysteresis may reflect pulley movement and might allow higher acuity, if a near point is transiently fixated just before a far target. The acuity domains provide new and more comprehensive evaluations of both pre- and posttherapy visual function than do primary-position acuity measurements, suggesting that high-visual-acuity fields should be included in clinical measures of visual function in nystagmus.
研究在两名因集合而抑制的婴儿型眼球震颤（IN）患者中，不同治疗方法所导致的集合诱导波形和高敏锐度视野的改善情况，并报告其中一名患者的一项新发现。
利用红外反射测量在不同注视和集合角度注视目标时的眼动情况，并使用扩展的眼球震颤敏锐度函数（NAFX）评估所有注视点处IN波形的中心凹注视质量。
记录显示，在远距离时，两名患者均表现出典型的零点（高NAFX值），在零点外侧的注视角度处NAFX降低。S1接受棱镜治疗，S2接受手术治疗。当通过底向外棱镜（S1）在近距离或远距离集合时，或在双眼内直肌后徙和双侧直肌切断术后（S2），零点和外侧注视角度处的NAFX均更高；零点区域变宽。对于S1，近距离时最长的中心凹注视域（NAFX在其峰值的10%以内的注视角度）比远距离时宽三倍，对于S2，术后比术前宽两倍。治疗改善域（治疗后NAFX高于治疗前的注视角度）甚至更宽。在中央20度注视范围内的固定注视角度下，S1的NAFX随聚散度的变化表现出滞后现象，散开时高于集合时；S2术后未表现出滞后现象。
通过手术或棱镜诱导集合来抑制IN，拓宽了具有更高中心凹注视质量的注视角度范围，类似于直肌切断术的零点拓宽效应。聚散度滞后现象的发现可能反映了滑车运动，如果在远距离目标之前短暂注视近点，可能会提高敏锐度。与主要注视位敏锐度测量相比，敏锐度域为治疗前和治疗后的视觉功能提供了更新颖、更全面的评估，表明高视觉敏锐度视野应纳入眼球震颤视觉功能的临床测量中。
