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Patrick A Sibony, Robert A Honkanen, Mark J Kupersmith, James Rohlf; Peripapillary RPE-layer shape changes in Idiopathic Intracranial Hypertension before and after treatment. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5106.
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We have previously reported that the shape of the peripapillary-RPE(ppRPE) layer in papilledema has an inverted U-shape indentation to mild flattening of the globe compared normals who exhibit a V-shape . This study attempts to determine the magnitude and type of shape changes that occur with a decrease in CSF pressure that follows lumbar puncture and after successful treatment.
We studied 30 patients with idiopathic intracranial hypertension; 27 female, mean age 25.6. We used the SD-OCT to evaluate three groups with respect to 1.shape of the RPE layer (using Geometric Morphometrics [1-4] ), 2.anterior-posterior displacement of the RPE layer at its margin and 3. RNFL thickness. We compared eyes with: A. papilledema before (Pre) and after lumbar puncture (P-lp), B. before (Pre) and after treatment with resolution(P-r); C.resolved papilledema(P-r) to normal controls.
There was a statistically significant difference in the shape of the RPE-layer after LP (p=.004) and after resolution(p=.001) compared to the Pre. The inverted-U indentation of the globe decreased slightly after LP and decreased further in the P-r group. Despite “resolution”, the P-r shape was statistically different (p=.001) from normals. The average posterior displacement after spinal tap was -78um ; and -215um after resolution . The mean RNFL at presentation was 278um, and decreased to 94u with resolution. There was a statistically significant (p=0.000) decrease of the mean RNFL(56um) after LP(before treatment). Displacement correlated with shape changes (r=.87,p=0.000). There was a statistically significant but mild correlation between displacement and RNFL change (r=.37, p=.01), shape and average RNFL (r =.44,p=.002).
The changes in the ppRPE-shape are dynamic and presumably reflect a decrease in the intracranial pressure after LP and treatment. There is a complex relationship between the translaminar pressure, scleral compliance and structural geometry of the neural canal that affects the shape of the peripapillary eye wall5. Peripapillary deformations may be useful in the diagnosis and management of intracranial hypertension.
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