Romano Paul E
Department of Ophthalmology, University of Florida, Gainesville, FL, USA.
Binocul Vis Strabismus Q. 2006;21(1):45-6.
The HR (prism diopters [PD] per mm of corneal light reflection test [CLRT] asymmetry for strabometry) varies in humans from 14 to 24 PD/mm, but is totally unpredictable. Photo(grammetric) HR calibration in (of) each case facilitates acceptable strabometry precision and accuracy.
Take 3 flash photos of the patient with both the preferred eye and then the deviating eye fixating straight ahead and then again with the deviation eye fixing at (+/-5-10 PD) the strabismic angle on a metric rule (stick) one meter away from the camera lens (where 1 cm = 1 PD).
On these 3 photos, make four precise measurements of the position of the CLR with reference to the limbus: In the deviating eye fixing straight ahead and fixating at the angle of deviation. Divide the mm difference in location into the change in the angle of fixation to determine the HR for this patient at this angle. Then determine the CLR position in both the deviating eye and the fixing eye in the straight ahead primary position picture. Apply the calculated calibrated HR to the asymmetry of the CLRs in primary position to determine the true strabismic deviation.
This imaging method insures accurate Hirschberg CLRT strabometry in each case, determining the deviation in "free space", under conditions of normal binocular viewing, uncontaminated by the artifacts or inaccuracies of other conventional strabometric methods or devices. So performed, the Hirschberg CLRT is the gold standard of strabometry.
用于斜视测量的角膜光反射试验（CLRT）的水平率（每毫米角膜光反射试验不对称性的棱镜度[PD]）在人类中为14至24 PD/mm，但完全不可预测。对每个病例进行摄影（测量）水平率校准有助于获得可接受的斜视测量精度和准确性。
拍摄患者3张闪光照片，先让优势眼注视正前方，然后让斜视眼注视正前方，再让斜视眼在距离相机镜头1米的米尺（杆）上以（±5 - 10 PD）斜视角度注视。
在这3张照片上，参照角膜缘对角膜光反射（CLR）的位置进行四次精确测量：斜视眼注视正前方时以及注视斜视角度时。将位置上的毫米差异除以注视角度的变化，以确定该患者在此角度下的水平率。然后在斜视眼和注视眼注视正前方的初始位置照片中确定CLR位置。将计算出的校准水平率应用于初始位置CLR的不对称性，以确定真正的斜视偏差。
这种成像方法确保了在每种情况下准确的 Hirschberg CLRT 斜视测量，在正常双眼视觉条件下，在“自由空间”中确定偏差，不受其他传统斜视测量方法或设备的伪影或不准确性的影响。如此进行的 Hirschberg CLRT 是斜视测量的金标准。
