Role of new magnetic resonance imaging modalities in diagnosis of orbital masses: a clinicopathologic correlation

To evaluate the role of diffusion-weighted magnetic resonance imaging [MRI] and proton magnetic resonance spectroscopy [MRS] in the diagnosis of different orbital masses and their advantages over conventional MRI. The study included 20 patients presenting with proptosis. Every patient was subjected to thorough clinical examination, conventional MRI [Tl weighted, T2 weighted, and postcontrast Tl weighted if needed,] diffusion-weighted MRI, and proton MRS. Orbitotomy was performed, the orbital mass was excised, and histopathological examination was performed. Diffusion-weighted MRI could differentiate between benign lesions and malignant tumors in 70% of cases; however, overlap occurred in 30% of cases with benign tumors showing restricted diffusion whereas proton MRS could differentiate between benign and malignant tumors in 90% of cases. Diffusion-weighted MRI and proton MRS can potentially increase the accuracy of diagnosis of orbital masses through in vivo tissue characterization. Magnetic resonance spectroscopy seems to be the more accurate modality

Intra-ocular lens power calculation in patients with high axial myopia before cataract surgery

To evaluate the accuracy of different formulas used for IOL power calculation in patients with high axial myopia undergoing cataract surgery. A prospective clinical study was carried out on 53 eyes of 51 patients with an axial length from 25.5 to 31.4 mm including 21 males [41.2%] and 30 females [58.8%]. Calculation of the IOL power to be implanted was done by three available IOL power formulas; Haigis formula, SRK/T formula, and Holladay I formula. The mean error [ME] was calculated from the difference between the formula predicted refractive error and the actual post operative refractive error. There was no statistically significant difference between the mean error of the three formulas used in the overall performance or in the axial length subcategories. SRK/T formula caused the smallest mean error, [+0.17 D]. Haigis formula showed a higher ME [+0.21 D] and Holladay formula caused a myopic postoperative refractive error [+0.20 D]. The calculation of IOL power in patients with high axial myopia using the third or the fourth generation formulas help in improvement of the accuracy of the calculation and decreasing the post operative refractive error. SRK/T formula showed the lowest mean error, however, there was not statistically significant difference between the three formulas used, neither in the overall performance, nor in axial length subcategories