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Abstract This study employed in vivo 7-T magnetic resonance imaging (MRI) to evaluate the postnatal ocular growth patterns under normal development or neonatal impairments in Sprague–Dawley rats. Using T2-weighted imaging on healthy rats from postnatal day (P) 1 (newborn) to P60 (adult), the volumes of the anterior chamber and posterior chamber (ACPC), lens, and vitreous humor increased logistically with ACPC expanding by 33-fold and the others by fivefold. Intravitreal potassium dichromate injection at P1, P7, and P14 led to T1-weighted signal enhancement in the developing retina by 188–289%. Upon unilateral hypoxic-ischemic encephalopathy at P7, monocular deprivation at P15, and monocular enucleation at P1, T2-weighted imaging of the adult rats showed decreased ocular volumes to different extents. In summary, in vivo high-field MRI allows for non-invasive evaluation of early postnatal development in the normal and impaired rat eyes. Chromium-enhanced MRI appeared effective in examining the developing retina before natural eyelid opening at P14 with relevance to lipid metabolism. The reduced ocular volumes upon neonatal visual impairments provided evidence to the emerging problems of why some impaired visual outcomes cannot be solely predicted by neurological assessments and suggested the need to look into both the eye and the brain under such conditions.

Purpose: The p.(Leu450Trp) COL8A2 mutation, associated with an early-onset corneal endothelial dystrophy, can result in bullous keratopathy within the first few decades of life. People with this condition frequently experience anterior corneal changes in keratometry as the disease worsens, which may potentially affect refractive error after endothelial keratoplasty. We describe outcomes of the first cases of Descemet Membrane Endothelial Keratoplasty (DMEK) for patients with known mutations in this gene. Observations: Four eyes from two patients with COL8A2-associated corneal dystrophy underwent DMEK for this condition at a tertiary academic center. Preoperative and postoperative Scheimpflug imaging and manifest refraction was conducted. Mean central corneal thickness decreased from 713 μm preoperatively to 529 μm at one month. Despite long-standing corneal haze, all eyes reached between 20/20 and 20/30 best corrected visual acuity, and minimum postoperative central corneal thickness reached 482, 479, 479 and 533 μm. Refractive changes frequently occurred during the first postoperative year, with 3.6 D, 3.3 D, 3 D, and 0.8 D shifts in spherical equivalent taking place within this time period in the four eyes. Conclusions and Importance: In two patients with the p.(Leu450Trp) mutation in COL8A2 who underwent DMEK, resolution of corneal edema resulted in centrally thin corneas and refractive shifts postoperatively. Despite chronic edema, excellent visual acuity was achieved in all eyes.

Visual function has been shown to deteriorate prior to the onset of retinopathy in some diabetic patients and experimental animal models. This suggests the involvement of the brain's visual system in the early stages of diabetes. In this study, we tested this hypothesis by examining the integrity of the visual pathway in a diabetic rat model using in vivo multi-modal magnetic resonance imaging (MRI). Ten-week-old Sprague-Dawley rats were divided into an experimental diabetic group by intraperitoneal injection of 65 mg/kg streptozotocin in 0.01 M citric acid, and a sham control group by intraperitoneal injection of citric acid only. One month later, diffusion tensor MRI (DTI) was performed to examine the white matter integrity in the brain, followed by chromium-enhanced MRI of retinal integrity and manganese-enhanced MRI of anterograde manganese transport along the visual pathway. Prior to MRI experiments, the streptozotocin-induced diabetic rats showed significantly smaller weight gain and higher blood glucose level than the control rats. DTI revealed significantly lower fractional anisotropy and higher radial diffusivity in the prechiasmatic optic nerve of the diabetic rats compared to the control rats. No apparent difference was observed in the axial diffusivity of the optic nerve, the chromium enhancement in the retina, or the manganese enhancement in the lateral geniculate nucleus and superior colliculus between groups. Our results suggest that streptozotocin-induced diabetes leads to early injury in the optic nerve when no substantial change in retinal integrity or anterograde transport along the visual pathways was observed in MRI using contrast agent enhancement. DTI may be a useful tool for detecting and monitoring early pathophysiological changes in the visual system of experimental diabetes non-invasively.