Third nerve palsy associated with preeclampsia and HELLP syndrome

Preeclampsia can cause myriad organ dysfunction, including cranial nerve palsies that pose diagnostic and management dilemmas. We present an unusual case of third nerve palsy, (presenting as diplopia, ptosis) with hypertension, hyperreflexia, proteinuria, easy bruising in a parturient at 34 + 6/52 weeks of twins gestation. She was treated as for severe preeclampsia and HELLP syndrome; intravenous magnesium sulphate and labetalol commenced and emergent cesarean delivery performed under general anesthesia due to concerns of low platelets and for airway protection should her glascow coma scale (GCS) deteriorate. Postoperatively, stroke, aneurysm and intra-cerebral causes of third nerve palsy were excluded, with subsequent recovery of symptoms upon blood pressure normalization. The eye signs are postulated to be due to two preeclamptic mechanisms involving disordered cerebral autoregulation: (1) hyperperfusion and breakdown of the blood–brain barrier that occurs with rising hypertension, causing fluid/blood product extravasation into brain parenchyma, or (2) focal reactive vasoconstriction and local hypoperfusion, contributed to by endothelial dysfunction.     

Auto-adjusted 3-D optic disk viewing from low-resolution stereo fundus image

Three-dimensional (3-D) visualization of the optic nerve head (optic disk) is very useful for clinical applications. It allows clinicians to measure the disk parameters more accurately and thus make the pathological diagnosis and progression monitoring easier. This paper describes an automatic, precise, 3-D optic nerve head reconstruction method from a pair of stereo images for which efficient steps including sparse-image registration and dense-depth recovery are used. A combination of two registration methods is used to detect the sub-pixel correspondences. The proposed method takes advantages of both the correlation methods which is robust to noise and the feature-based method on its accuracy. The searching range in image registration is auto-adjusted based on the previous iteration result. Only sparse matched points are computed to speed up the processing and the sub-pixel matching is used to overcome the problem of low resolution in the image. This is followed by the piecewise cubic interpolation to obtain the dense disparities and depths. Multiple windowing is applied here by first using the large window to obtain basic disparities followed by the small window and previous basic disparities to measure details. The result is then smoothed and displayed as the final 3-D shape.     

Three dimensional optic disc visualisation from stereo images via dual registration and ocular media optical correction

BACKGROUND/AIMS: The three dimensional (3-D) visualisation of the optic disc in true colour will give essential meaning in clinical application. It is not only useful for clinicians in the evaluation of the condition of the optic disc, but it also simplifies the pathological diagnosis and disease progression monitoring. This paper describes a complete 3-D optic disc reconstruction method from a pair of stereo images by a series of robust procedures including camera calibration, image registration, depth recovery, and ocular media optical inclusion. METHODS: Two registration techniques (correlation and feature based methods) are combined together to prune the uncertain matching points in order to improve the overall accuracy of registration. The ocular media within the eyeball are lump modelled as a single lens and integrated into the reconstruction process to obtain an accurate 3-D optic disc image. CONCLUSION: The recovered 3-D optic disc images show good consistency and compatibility when compared with the results from Heidelberg retina tomography (HRT) under clinical validation, with an additional advantage of implementing a more economical and conventional mode of retinal image acquisition.