Seyed Javad Hashemian MD Eye Research Center Rasoul Akram Hospital Tehran University of Medical Sciences No financial interest ASCRS, San Diego, March /27/ 2011 Direct Measurement of the Ciliary Sulcus Diameter by Ultrasound Biomicroscopy and Correlation with White to White measurement. In the name of GOD

lens sizes & Correspondence between white-to-white and sulcus diameter Published studies have not found any anatomical correspondence between white-to- white and sulcus diameter, suggesting that some lens sizing issues may be explained by the assumption that sulcus diameter can be estimated from white-to-white. Posterior chamber phakic IOLs using a sizing criteria of adding 0.50 mm to the white-to-white in eyes where the anterior chamber depth (ACD) was 2.80 to 3.50 mm, and adding 1.00 mm to the white-to-white in eyes where the ACD was >3.50 mm. The common theme regarding postoperative complications of posterior chamber phakic IOL surgery is that of lens sizing An oversized lens can cause angle closure leading to malignant glaucoma, or the lens can chafe the iris leading to pigment dispersion An undersized lens can cause cataract or damage to the zonules with dislocation of the phakic IOL Recently, a 35-MHz UBM was developed, and this device seems to be more accurate than other methods because it can measure ciliary sulcus diameter from 1 image, even though the image resolution is not as good as that of 50-MHz UBM. In the present study, we measured ciliary sulcus diameters using a 35-MHz UBM and evaluated the correlation with white-to-white distances. In the present study, we measured ciliary sulcus diameters using a 35-MHz UBM and evaluated the correlation with white-to-white distances.

Horizontal white-to-white distances were measured by scanning slit topography using Orbscan IIz (Bausch & Lomb) UBM ciliary sulcus measurement Topical tetracaine 0.5% was instilled to anesthetize the cornea before measurement. One of 3 differently sized eyecups (18 mm, 20 mm, and 22 mm) was inserted depending on the ocular aperture size. An eyecup was filled with sterile normal saline and the subject was asked to fixate on a ceiling target with the fellow eye to maintain accommodation and fixation. Diameters of the ciliary sulcus were measured using a VuMax-II UBM equipped with a 35-MHz transducer. Cross-sectional images were obtained on the horizontal meridians. Diameters of the ciliary sulcus were measured using a VuMax-II UBM equipped with a 35-MHz transducer. Cross-sectional images were obtained on the horizontal meridians. METHODS: To evaluate the correlation of white to white measurement between Caliper and Orbscan and relation to sulcus to sulcus dimension measured by UBM. In this cross-sectional observational study we measured sulcus to sulcus dimension of 203 eyes of high myopic patients who presented to be assessed for phakic IOL surgery. we measured sulcus to sulcus dimension by UBM and horizontal white-to-white distance using Orbscan IIz and Caliper. Mean W-W dimension, differences between methods of measurement and correlation with S- to- S diameter was evaluated. PURPOSES :

RESULTS: Mean W-W dimension in Caliper group was mm ±0.38 mm ( range mm), By Orbscan was 11.80mm ± 0.42 mm (range 10.5mm-13.2mm). Mean S-S dimension by UBM was 12.14mm ± 0.43mm ( range mm) Mean difference of S-S and W-W by Caliper was 0.49mm±0.26mm ( range mm) Mean difference of W-W by Orbscan – Caliper was 0.10mm ±0.25mm ( range mm). Correlation: The correlation of white to white diameter measured by Caliper and Orbscan with sulcus to sulcus dimension measured by UBM was 78.4% and 71% respectively.

Instrument Mean SDMinimumMaximum UBM Sulcus to Sulcus UBM Angle to Angle Orbscan IIz (WTW) Caliper (WTW) MeanSDCorrelation Coefficient P Value UBM Ciliary Sulcus Diameter (mm) Caliper White to white Diameter (mm) MeanSDCorrelation Coefficient P Value UBM Ciliary Sulcus Diameter (mm) Orbscan Iiz White to white Diameter (mm) MeanSDCorrelation Coefficient P Value Caliper White to white Diameter (mm) Orbscan Iiz White to white Diameter (mm)

CONCLUSIONS: The 35-MHz UBM is an accurate method for direct measurement of the ciliary sulcus diameter for proper determination of posterior chamber phakic IOL size The White-to-white measurements by Caliper and Orbscan are an acceptable method to predict the ciliary sulcus diameter in myopic patients if UBM is not available.