Kevin Vallotton

Ectopia lentis in the pediatric population poses significant surgical challenges given the need for long-term optical rehabilitation. This study evaluated

This study evaluates the biomechanical and optical consequences of three corneal refractive surgeries-PRK, LASIK, and KLEx-using patient-specific finite element simulations. Personalized corneal geometries were derived from preoperative tomography of 30 patients and subjected to virtual interventions modeled in a nonlinear anisotropic framework. Material parameters were calibrated from experimental human corneal data. Stress distributions and refractive outcomes were computed under physiological intraocular pressure. Despite identical tissue removal volumes, PRK preserved a more uniform stress distribution and delivered the least optical undercorrection. LASIK induced significant posterior stromal stress and KLEx, although mechanically intermediate, exhibited greater undercorrection due to cap-induced tension. The results support the integration of biomechanics-informed modeling in refractive surgery planning.

Purpose: The purpose of this study was to develop a deep learning algorithm, to detect retinal breaks and retinal detachments on ultra-widefield fundus (UWF) optos images using artificial intelligence (AI). Methods: Optomap UWF images of the database were annotated to four groups by two retina specialists: (1) retinal breaks without detachment, (2) retinal breaks with retinal detachment, (3) retinal detachment without visible retinal breaks, and (4) a combination of groups 1 to 3. The fundus image data set was split into a training set and an independent test set following an 80% to 20% ratio. Image preprocessing methods were applied. An EfficientNet classification model was trained with the training set and evaluated with the test set. Results: A total of 2489 UWF images were included into the dataset, resulting in a training set size of 2008 UWF images and a test set size of 481 images. The classification models achieved an area under the receiver operating characteristic curve (AUC) on the testing set of 0.975 regarding lesion detection, an AUC of 0.972 for retinal detachment and an AUC of 0.913 for retinal breaks. Conclusions: A deep learning system to detect retinal breaks and retinal detachment using UWF images is feasible and has a good specificity. This is relevant for clinical routine as there can be a high rate of missed breaks in clinics. Future clinical studies will be necessary to evaluate the cost-effectiveness of applying such an algorithm as an automated auxiliary tool in a large practices or tertiary referral centers. Translational Relevance: This study demonstrates the relevance of applying AI in diagnosing peripheral retinal breaks in clinical routine in UWF fundus images.

Background and Purpose: The timing of decision‐making for a surgical intervention in patients with mild degenerative cervical myelopathy (DCM) is challenging. Spinal cord motion phase contrast MRI (PC‐MRI) measurements can reveal the extent of dynamic mechanical strain on the spinal cord to potentially identify high‐risk patients. This study aims to determine the comparability of axial and sagittal PC‐MRI measurements of spinal cord motion with the prospect of improving the clinical workup. Methods: Sixty‐four DCM patients underwent a PC‐MRI scan assessing spinal cord motion. The agreement of axial and sagittal measurements was determined by means of intraclass correlation coefficients (ICCs) and Bland‐Altman analyses. Results: The comparability of axial and sagittal PC‐MRI measurements was good to excellent at all cervical levels (ICCs motion amplitude: .810‐.940; p < .001). Significant differences between axial and sagittal amplitude values could be found at segments C3 and C4, while its magnitude was low (C3: 0.07 ± 0.19 cm/second; C4: −0.12 ± 0.30 cm/second). Bland‐Altman analysis showed a good agreement between axial and sagittal PC‐MRI scans (coefficients of repeatability: minimum −0.23 cm/second at C2; maximum −0.58 cm/second at C4). Subgroup analysis regarding anatomic conditions (stenotic vs. nonstenotic segments) and different velocity encoding (2 vs. 3 cm/second) showed comparable results. Conclusions: This study demonstrates good comparability between axial and sagittal spinal cord motion measurements in DCM patients. To this end, axial and sagittal PC‐MRI are both accurate and sensitive in detecting pathologic cord motion. Therefore, such measures could identify high‐risk patients and improve clinical decision‐making (ie, timing of decompression).

This study compares remote neurodegenerative changes caudal to a cervical injury in degenerative cervical myelopathy (DCM; i.e., non-traumatic) and incomplete traumatic spinal cord injury (tSCI) patients, using magnetic resonance imaging (MRI)–based tissue area measurements and diffusion tensor imaging (DTI). Eighteen mild-to-moderate DCM patients with sensory impairments (modified Japanese Orthopedic score: 16.2 ± 1.9), 14 incomplete tetraplegic tSCI patients (American Spinal Injury Association Impairment Scale C and D), and 20 healthy controls were recruited. All participants received DTI and T2*-weighted scans in the lumbosacral enlargement (caudal to injury) and at C2/C3 (rostral to injury). MRI readouts included DTI metrics in the white matter (WM) columns and cross-sectional WM and gray matter area. One-way analysis of variance with Tukey's post hoc comparison ( p < 0.05) was used to assess group differences. In the lumbosacral enlargement, compared with DCM, tSCI patients exhibited decreased fractional anisotropy in the lateral (tSCI vs. DCM, -11.9%, p = 0.007) and ventral WM column (-8.0%, p = 0.021), and showed a trend toward lower values in the dorsal column (-8.9%, p = 0.068). At C2/C3, compared with controls, fractional anisotropy was lower in both groups in the dorsal (DCM vs. controls, -7.9%, p = 0.024; tSCI vs. controls, -10.0%, p = 0.007) and in the lateral column (DCM: -6.2%, p = 0.039; tSCI: -13.3%, p < 0.001), while tSCI patients had lower fractional anisotropy than DCM patients in the lateral column (-7.6%, p = 0.029). WM areas were not different between patient groups but were lower compared with controls in the lumbosacral enlargement (DCM: -16.9%, p < 0.001; tSCI: -10.5%, p = 0.043) and at C2/C3 (DCM: -16.0%, p < 0.001; tSCI: -18.1%, p < 0.001). In conclusion, mild-to-moderate DCM and incomplete tSCI lead to similar degree of degeneration of the dorsal and lateral columns at C2/C3, but tSCI results in more widespread white matter damage in the lumbosacral enlargement. These remote changes are likely to contribute to the patients' impairment and recovery. DTI is a sensitive tool to assess remote pathological changes in DCM and tSCI patients.

Objectives This study compares remote neurodegenerative changes caudal to a cervical injury in degenerative cervical myelopathy (DCM) (i.e. non-traumatic) and incomplete traumatic spinal cord injury (tSCI) patients, using MRI-based tissue area measurements and diffusion tensor imaging (DTI). Methods Eighteen mild to moderate DCM patients with sensory impairments (mean mJOA score: 16.2), 14 incomplete tetraplegic tSCI patients (AIS C&D), and 20 healthy controls were recruited. All participants received DTI and T2*-weighted scans in the lumbosacral enlargement (caudal to injury) and at C2/C3 (rostral to injury). MRI readouts included DTI metrics in the white matter (WM) columns and cross-sectional WM and gray matter area. One-way ANOVA with Tukey post-hoc comparison (pResults In the lumbosacral enlargement, compared to DCM, tSCI patients exhibited decreased fractional anisotropy in the lateral (tSCI vs. DCM, −11.9%, p=0.007) and ventral WM column (−8.0%, p=0.021), and showed trend toward lower values in the dorsal column (−8.9%, p=0.068). At C2/C3, no differences in DTI metrics were observed between DCM and tSCI, but compared to controls, fractional anisotropy was lower in both groups in the dorsal (DCM vs. controls, −7.9%, p=0.024; tSCI vs. controls, −10.0%, p=0.007) and in the lateral column (DCM: −6.2%, p=0.039; tSCI: −13.3%, pConclusion In conclusion, mild to moderate DCM and incomplete tSCI lead to similar degree of degeneration of the dorsal and lateral columns at C2/C3, but tSCI results in more widespread white matter damage in the lumbosacral enlargement. These remote changes are likely to contribute to the impairment and recovery of the patients. Diffusion MRI is a sensitive tool to assess remote pathological changes in DCM and tSCI patients.

This study aims to determine tissue-specific neurodegeneration across the spinal cord in patients with mild-moderate degenerative cervical myelopathy (DCM). Twenty-four mild-moderate DCM and 24 healthy subjects were recruited. In patients, a T2-weighted scan was acquired at the compression site, whereas in all participants a T2*-weighted and diffusion-weighted scan was acquired at the cervical level (C2–C3) and in the lumbar enlargement (i.e., rostral and caudal to the site of compression). We quantified intramedullary signal changes, maximal canal and cord compression, white (WM) and gray matter (GM) atrophy, and microstructural indices from diffusion-weighted scans. All patients underwent clinical (modified Japanese Orthopaedic Association; mJOA) and electrophysiological assessments. Regression analysis assessed associations between magnetic resonance imaging (MRI) readouts and electrophysiological and clinical outcomes. Twenty patients were classified with mild and 4 with moderate DCM using the mJOA scale. The most frequent site of compression was at the C5–C6 level, with maximum cord compression of 38.73% ± 11.57%. Ten patients showed imaging evidence of cervical myelopathy. In the cervical cord, WM and GM atrophy and WM microstructural changes were evident, whereas in the lumbar cord only WM showed atrophy and microstructural changes. Remote cervical cord WM microstructural changes were pronounced in patients with radiological myelopathy and associated with impaired electrophysiology. Lumbar cord WM atrophy was associated with lower limb sensory impairments. In conclusion, tissue-specific neurodegeneration revealed by quantitative MRI is already apparent across the spinal cord in mild-moderate DCM before the onset of severe clinical impairments. WM microstructural changes are particularly sensitive to remote pathologically and clinically eloquent changes in DCM.