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Daniel Lee, Melissa A Wilk, Brandon J Lujan, Bhavna J Antony, Joseph Carroll; Correlating Foveal Pit Morphology To Outer Nuclear and Henle Fiber Layer Topography. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1526.
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Prior studies have used traditional SD-OCT imaging to elucidate relationships between the outer nuclear layer (ONL) and foveal specialization (Tick et al, 2011; Yanni et al, 2012; Menghini et al, 2015). However, SD-OCT does not clearly delineate the ONL and the overlying Henle fiber layer (HFL) which can lead to inaccurate measurements. Directional optical coherence tomography (D-OCT) is an OCT technique which allows for clear delineation of the ONL and HFL in vivo (Lujan et al, 2015). Here we use D-OCT to measure both foveal ONL and HFL thickness in subjects with no known ocular pathology in order to assess their respective relationships to foveal pit morphology.
Horizontal D-OCT B-scans were acquired, registered and averaged as previously described (Lujan et al, 2015). Averaged images were manually segmented to extract both true ONL and HFL thickness. Volume scans of the macula were used to derive pit depth, diameter and volume. Correlation between ONL or HFL thickness and various pit metrics (depth, diameter, volume) was assessed using Spearman r. Because three descriptors for foveal pit morphology were considered, we used the Holm-Bonferroni Method to minimize familywise error rate.
Fifty subjects, ages 8-67 (mean ± SD 25.36 ± 11.77), with no known ocular pathology were recruited for this study. Mean ONL thickness at the foveal center ranged from 78.01 to 118.32μm (mean ± SD 96.21±10.38μm) while HFL thickness at the foveal center ranged from 0.45 to 23.74μm (mean ± SD 9.78±6.40μm). On average, foveal HFL consisted of 8.85% of the measured ONL+HFL thickness. Foveal ONL thickness was found to be negatively correlated with pit depth (r = -0.50, p<0.001) and pit volume (r = -0.45, p < 0.01). No significant relationship was found between foveal ONL thickness and pit diameter. No significant relationship was found between foveal HFL thickness and pit depth, diameter or volume.
Consistent with prior literature, foveal ONL topography appears to be correlated with foveal pit morphology. Greater ONL thickness at the foveal center is associated with shallower foveal pits in normal subjects. We did not find a relationship between foveal HFL thickness and foveal pit morphology. Additional work is required to better elucidate the relationship between ONL and HFL topography with cone packing of the fovea.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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