RESUMEN
The implantable collamer lens(ICL)is a widely popular option for the correction of refractive errors. ICL implantation brings a whole new dimension to the vision, from the anterior chamber phakic ICL to the posterior and central hole ICL. Even though there are fewer reported complications, ICL size selection remains challenging due to the differences in device measurements and ICL sizing formulas. With the widening comprehensiveness of ICL implantation and the ongoing development of ophthalmic devices and technologies, particularly the advent of artificial intelligence, more and more indicators such as sulcus-to-sulcus(STS), crystalline lens rise(CLR), angle-to-angle(ATA), the iris pigment end to the iris pigment end(PTP), anterior chamber width(ACW), and anterior chamber angle(ACA)are providing references in the selection of ICL size, this article provides a review of ICL size selection.
RESUMEN
Background: Selection of adequate size double lumen tube (DLT) is complicated by marked inter-individual variability in morphology and dimensions of tracheobronchial tree. Computerized tomography (CT)-guided left bronchus width measurement has been used to predict adequate size DLT in European and Singapore population; however, no such data exist for Indian population who are racially different. We compared the effect of DLT size selection based on CT-guided bronchial width measurement to the conventional method of DLT selection on the adequacy of both lungs isolation and on the safety margin of right-sided DLT. Methods: Fifty-five adults scheduled to undergo thoracotomy were enrolled in this prospective observational study. An appropriate size left- or right-sided DLT with outer diameter 0.5–1 mm smaller than the CT-measured bronchial width was selected for the isolation of lungs. Adequacy of separation was checked using fiberoptic bronchoscope. The safety margin of selected right-sided DLT size was calculated from CT-measured right upper lobe bronchus width and diameter of right upper lobe ventilation slot of the DLT. Results: Adequate separation of lungs was achieved in 92.7% of studied population, 90.9% in males, and 95.4% in females. Among these, 54.9% patients required different sized DLT as compared to conventional method. Overall safety of margin of right-sided DLTs was comparable between two methods of DLT selection (median [IQR] 4.8 (3.5–6.8) vs. 6.59 (3.5–7.8), P = 0.317). DLT size with adequate isolation of lung correlated with height, tracheal width (TW) on chest X-ray, and age of the patients. A formula to calculate DLT size based on these variable was derived. Conclusion: CT-measured bronchial width predicts the appropriate DLT size better than conventional method. In the absence of CT scan facility, patient height, age, and chest X-ray TW may be used to predict DLT size with reasonable accuracy.