Abstract
Purpose: :
To measure ciliary sulcus diameters at 4 different axes and estimate in vivo dimensions of posterior chamber, and determine the relationship with white–to–white diameters.
Methods: :
Twenty eyes of ten subjects that had never had ocular surgery were studied with Orbscan and high frequency (35MHz) ultrasound (HiScan, Optikon) in sequential meridional scan planes at 45 degrees increments.
Results: :
The mean diameters of ciliary sulcus were 11.78±0.40 mm at 0 degree, 11.97±0.38 mm at 45 degrees, 12.42±0.36 mm at 90 degrees, and 11.99±0.46 mm at 135 degrees. In all eyes, vertical diameter was longer than horizontal diameter. Mean difference between vertical and horizontal diameter was 0.64±0.26 mm (range 0.36∼1.13 mm) and it was statistically significant (p=0.000). The relationship between white–to–white diameter and horizontal or vertical sulcus diameter was not correlated (r=0.264, 0.088, respectively).
Conclusions: :
The shape of posterior chamber was vertically oval. White–to–white technique to predict the horizontal diameter of ciliary sulcus was shown to be inaccurate. High frequency (35MHz) ultrasound biometry may be a good method to measure accurate diameters of ciliary sulcus for implantation of posterior chamber phakic intraocular lens.
Keywords: refractive surgery: phakic IOL • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)