The Rectification of Width and Area of the Ciliary Cleft in Dogs

The width and area of the ciliary cleft (CCW and CCA) measured by ultrasound biomicroscopy was rectified to compare dogs of different body sizes/weights: toy breeds group (TBG), small BG (SBG), medium BG (MBG), and large/giant BG (LGBG). A linear correlation was detected between the natural log of body weight and the ocular axial length (OAL) reflecting the ocular size (OS) (r=0.81, P<0.001). A significant positive correlation was found between OAL and the distance of the Schwalbe line—the anterior lenticular capsule (SLD) (r=0.87, P<0.001), suggesting that SLD could rectify canine OS. Rectified CCW (r-CCW) and rectified CCA (r-CCA) were calculated using SLD and fixed SLD as the SLD mean (SLDM). The SLDM was 2.55 mm in this study, and the r-CCW and the r-CCA were calculated as r-CCW = CCW × (2.55/SLD) and r-CCA = CCA × (2.55/SLD)2. The CCW values of TBG, SBG, and MBG were narrower than those of LGBG (P<0.05). There were significant statistical differences in the CCA between any groups other than TBG and SBG (P<0.05). While, there were no significant differences in the r-CCW and r-CCA in all groups. In addition, CCW/SLD did not show significant changes in dogs with different body sizes/weights. These results suggested that the r-CCW, r-CCA, and CCW/SLD were available for comparison between dogs of different body sizes/weights.