The retina is an attractive source of biomarkers since it shares many features with the brain. Thickness differences in 10 retinal layers between 19 patients with mild Alzheimer’s disease (AD) and a control group of 24 volunteers were investigated. Retinal layers were automatically segmented and their thickness at each scanned point was measured, corrected for tilt and spatially normalized. When the mean thickness of entire layers was compared between patients and controls, only the outer segment layer of patients showed statistically significant thinning. However, when the layers were compared point-by point, patients showed statistically significant thinning in irregular regions of total retina and nerve fiber, ganglion cell, inner plexiform, inner nuclear and outer segment layers. Our method, based on random field theory, provides a precise delimitation of regions where total retina and each of its layers show a statistically significant thinning in AD patients. All layers, except inner nuclear and outer segments, showed thickened regions. New analytic methods have shown that thinned regions are interspersed with thickened ones in all layers, except inner nuclear and outer segments. Across different layers we found a statistically significant trend of the thinned regions to overlap and of the thickened ones to avoid overlapping.

Penetrating injuries of the cranium are relatively uncommon, only 0.4% of all head injuries. In patients with disturbed conscious level, an extensive examination should be performed in the emergency unit to rule out transorbital penetrating brain injury. A 25-year-old male was attacked with a dagger. He presented with ethylic intoxication and the physical examination demonstrated a small skin injury on the lateral canthus of the left eye with a large periocular hematoma which prevented eyelid opening. Cranial CT scan showed a metallic intraorbital foreign body consisting of a fragment of a dagger which perforated the eyeball, and penetrated through the superomedial wall of the orbit into the anterior cranial fossa. Reconstruction of the eyeball was performed and the fragment was removed. Orbital injuries with a knife in situ are very unusual. Early identification and removal of retained foreign bodies are essential.

ObjectiveTo apply a fully automated method to quantify the 3D structure of the bony nasolacrimal canal (NLC) from CT scans whereby the size and main morphometric characteristics of the canal can be determined.DesignCross-sectional study.Subjects36 eyes of 18 healthy individuals.MethodsUsing software designed to detect the boundaries of the NLC on CT images, 36 NLC reconstructions were prepared. These reconstructions were then used to calculate NLC volume. The NLC axis in each case was determined according to a polygonal model and to 2nd, 3rd and 4th degree polynomials. From these models, NLC sectional areas and length were determined. For each variable, descriptive statistics and normality tests (Kolmogorov-Smirnov and Shapiro-Wilk) were established.Main Outcome MeasuresTime for segmentation, NLC volume, axis, sectional areas and length.ResultsMean processing time was around 30 seconds for segmenting each canal. All the variables generated were normally distributed. Measurements obtained using the four models polygonal, 2nd, 3rd and 4th degree polynomial, respectively, were: mean canal length 14.74, 14.3, 14.80, and 15.03 mm; mean sectional area 15.15, 11.77, 11.43, and 11.56 mm2; minimum sectional area 8.69, 7.62, 7.40, and 7.19 mm2; and mean depth of minimum sectional area (craniocaudal) 7.85, 7.71, 8.19, and 8.08 mm.ConclusionThe method proposed automatically reconstructs the NLC on CT scans. Using these reconstructions, morphometric measurements can be calculated from NLC axis estimates based on polygonal and 2nd, 3rd and 4th polynomial models.

There is growing evidence that thinned retinal regions are interspersed with thickened regions in all retinal layers of patients with Alzheimer’s disease (AD), causing roughness to appear on layer thickness maps. The hypothesis is that roughness of retinal layers, assessed by the fractal dimension (FD) of their thickness maps, is an early biomarker of AD. Ten retinal layers have been studied in macular volumes of optical coherence tomography from 24 healthy volunteers and 19 patients with mild AD (Mini-Mental State Examination 23.42 ± 3.11). Results show that FD of retinal layers is greater in the AD group, the differences being statistically significant (p < 0.05). Correlation of layer FD with cognitive score, visual acuity and age reach statistical significance at 7 layers. Nearly all (44 out of 45) FD correlations among layers are positive and half of them reached statistical significance (p < 0.05). Factor analysis unveiled two independent factors identified as the dysregulation of the choroidal vascular network and the retinal inflammatory process. Conclusions: surface roughness is a holistic feature of retinal layers that can be assessed by the FD of their thickness maps and it is an early biomarker of AD.

PurposeAlzheimer’s Disease (AD) is the most common cause of dementia. Retinal thickness changes had been reported in different stages of the disease, being these changes a biomarker of AD progression. There is increasing evidence that thinned and thickened regions are interspersed throughout the retinal layers of AD patients, resulting in the roughness of their bounding surfaces and thickness maps. The aim of this work is to prove the roughness of retinal layers, as assessed by the fractal dimension (FD) of their thickness maps, is an early biomarker of AD.MethodsA complete ophthalmological exam and cognitive test (Mini Mental State Examination) was carried out in 24 healthy volunteers and 19 patients with mild AD. Total retinal thickness and retinal layers thickness were studied by optical coherence tomography (OCT) and thickness retinal maps were obtained. From the whole retinal area scanned on each subject only a central square region available from all sample subjects was kept for roughness analysis. In this square, the FD of the thickness map of each retinal layer was calculated as an index of its roughness.ResultsThe FD of retinal layers is significantly higher (p < 0.05) in the AD group, compared to the healthy group. The correlation of FD with cognitive score, visual acuity and age reaches statistical significance in 7 layers. Nearly all (44 out of 45) FD correlations among layers are positive and half of them (23) reached statistical significance (p  <  0.05). Factor analysis revealed two groups of retinal layers whose roughness evolves independently: the first includes two layers related to the outer segments and may be influenced by dysregulation of the choroidal vascular network; and the second includes the remaining layers, and may be associated with the inflammatory process of the retina.ConclusionsRoughness is a holistic feature of retinal layers that can be assessed by FD of their thickness maps and is an early biomarker of AD.