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G. M. Mandel, M. Durbin, M. J. Kupersmith, R. H. Kardon; Spectral Domain OCT Parameters to Measure Papilledema Due to Intracranial Hypertension. Invest. Ophthalmol. Vis. Sci. 2010;51(13):647.
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© ARVO (1962-2015); The Authors (2016-present)
To quantify the effects of papilledema on the optic disc and peripapillary retinal fiber layer (RNFL) due to intracranial hypertension.
We compared spectral domain OCT (Cirrus HD-OCT) findings in patients with papilledema due to intracranial hypertension to patients with comparable optic disc swelling, without intracranial hypertension, due to acute optic neuritis (ON) and non-arteritic anterior ischemic optic neuropathy (NAION). We compared volume of RNFL and total retinal volume by quadrants in the peripapillary retina. We manually measured the height of disc swelling from the plane of Bruch’s membrane (BM) and also attempted to measure the diameter of the neural canal from temporal to nasal borders of Bruch’s membrane.
The range for volume of RNFL was 0.63 to 1.84 mm3 and for total retina was 1.8 to 3.2 mm3 for papilledema. The range of tissue volume was similar for NAION, ON and papilledema. Total retinal and RNFL volume by quadrant correlated well (R2 = 0.7 to 0.9) for all 3 disorders. Manual measurement of optic disc swelling correlated less well with average RNFL (R2 = 0.55 for papilledema, 0.57 for ON, 0.49 for NAION). The RNFL and disc finding algorithms failed with severe swelling: of 22 swollen discs due to papilledema, 10 failed accurate identification of the disc borders, and 4 had failed RNFL algorithm. Of 8 NAION eyes, 4 failed the RNFL algorithm, and 3 failed disc border identification. Of 6 ON cases, 1 failed disc border identification, and none had RNFL failures. Even in cases with ‘successful’ RNFL layer measurement, the calculated thickness may include other layers, precluding accurate RNFL loss measurement. The BM borders were difficult to distinguish with acute swelling and became more distinct as swelling resolved in all 3 disorders.
Quantifying the effects of papilledema on the optic disc and peripapillary RNFL remains problematic with current software segmentation algorithms. Most techniques are designed to quantify optic disc and RNFL loss due to glaucoma and other optic neuropathies. With algorithms tailored for analyzing optic disc edema, relating these changes to vision loss at presentation and judging the effects of intervention may become more accurate. Total retinal thickness and RNFL analysis indicate when swelling is present, but quantifying RNFL tissue loss requires resolution of swelling or new methods of analysis.
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