الفهرس | Only 14 pages are availabe for public view |
Abstract With the emergence of modern surgical techniques, patients have increasingly higher refractive expectations. To achieve optimal refractive outcomes, IOL power calculation is important. IOL power is calculated using preoperative biometric measurements such as AL, corneal power, ACD and an estimation of postoperative effective lens position. Optical biometers - as the partial coherence interferometry (PCI)-based IOLmaster used in our study - have gained more preference over the previously used applanation ultrasound (A-scan) biometry. Previous studies showed no statistically significant correlation between AL and ACD in eyes with AL of 27.5 mm or greater while positive statistically significant correlation existed in eyes shorter than 27.5 mm. In short eyes, some studies suggest that the Hoffer Q formula produced significantly more accurate ELP prediction than the Haigis formula in eyes with an ACD < 2.5 mm. While other studies showed that the Hoffer Q formula overestimates ELP in eyes with a short AL and a shallow ACD. Normal eyes show no significant difference between the five formulas (Haigis, SRK-II, Hoffer Q, SRK/T and Holladay 1). Some studies recommend using the Holladay 1 formula as the most accurate. In long eyes, the SRK/T and the Haigis formulas are reportedly more accurate than other formulas. The results of our study showed that the correlation between the axial length and the anterior chamber depth among short eyes was statistically significant and they were negatively correlated, while no statistically significant correlation existed between AL and ACD in normal and long eyes. Our observation that the correlation between AL and ACD differs in normal and long eyes suggests the importance of the IOL formulas such as Haigis, Holladay II and Barrett Universal Formula II which take into consideration the ACD as a separate variable when calculating the IOL power. |