The Inner Retinal Layers of Megalopapilla Mesasured by Optical Coherence Tomography

Rita Gama, Catarina Relha, Joana Gomes Costa, Nuno Eiro


The primary purpose was to assess the differences on the peripapillary retinal nerve fiber layer (pRNFL) and the ganglion cell-inner plexiform layer (GCIPL) thicknesses between subjects with megalopapilla (MP) and physiologic large cup discs (LCD) measured by a spectral-domain optical coherence tomography. The secondary purpose was is to determine whether the pRNFL and GCIPL thicknesses increase with the optic nerve head (ONH) area.

This is a cross-sectional study that included 184 eyes, 92 diagnosed as MP and 92 as LCD. LCD constituted a sex-and-age-matched control group. All subjects were imaged with Cirrus HD-OCT. Macula and pRNFL thicknesses maps for each subject were obtained.

The inferior quadrant pRNFL thickness was higher on the MP group than LCD group (p<0.05). There were no differences on the GCIPL thickness between the two groups. A positive correlation was found between average, superior and inferior quadrant pRNFL thickness and the ONH area (p<0.05). The steepness of the correlation curve was higher on the inferior quadrant. No correlation was found between GCIPL thickness and ONH area. Comparing with LCD, the inferior quadrant pRNFL thickness of MP patients is higher. As the ONH area increases, average, superior and inferior quadrant pRNFL thickness also increases.

Based on our findings, in MP subjects, the assessment of a glaucomatous lesion based on the pRNFL thickness measurements is not reliable. The authors recommend that, in these patients, the evaluation of glaucoma damage privileges the GCIPL thickness map analysis rather than the pRNFL thickness.

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