Purpose:
To assess papillary thickness (PT) of the optic nerve head (ONH) in patients with papilledema, using a spectral-domain optical coherence tomography (SD-OCT) star-pattern scan (SPS) acquisition protocol. Past studies have used peripapillary total retinal thickness (PRT) for ONH edema. We postulate that measurement of PT provides a more accurate baseline measure for diagnosis and follow-up of papilledema.
Methods:
A comparative case series of 8 eyes from 4 patients with newly diagnosed papilledema and 8 eyes from 4 healthy subjects. PRT and PT were both evaluated with SD-OCT: for PTR we used a macular cube acquisition protocol centred on the optic disc, and for PT we used a SPS consisting of 48 radial slices through the ONH. PT was measured from the end of Bruch’s membrane to the top of the ONH. Mean Thickness values were calculated in four quadrants and compared between them and with the control group.
Results:
For papilledema patients, mean PT were 647±87.7 µm, 441±83.7 µm, 609±104.7 µm and 614±92.8 µm for the superior (S), temporal (T), inferior (I) and nasal (N) quadrants, respectively. These PT values were significantly higher than PRT values in all quadrants (S: +75 µm, T: +65 µm, I: +82 µm, and N: +125 µm, P=0.012-0.036). When compared with the control group, PT was significantly higher in all four quadrants (average thickness: 577 ±120 µm vs 357 ±70 µm for control, P=0.001); moreover, the difference between PT and PRT values was significantly higher in the S (P=0.009), T (P=0.005), and N (P=0.001) quadrants.
Conclusions:
PT measured with SD-OCT SPS acquisition protocol is significantly higher than PRT when compared with a control group. We speculate that PT is a more sensitive sign to monitor disease progression and response to treatment than PRT since it represents more accurately the clinical evaluation of papilledema. To our knowledge this is the first study using SPS for the diagnosis of ONH edema. Our pilot study’s aim is to validate the measurement method for future prospective studies that will compare the changes in PT and PRT during the evolution of papilledema.
Keywords: neuro-ophthalmology: optic nerve • neuro-ophthalmology: diagnosis • imaging/image analysis: clinical