Purpose The outer nuclear layer (ONL) contains photoreceptor nuclei, and its thickness is an important biomarker for retinal degenerations. Accurate ONL thickness measurements are obscured in standard optical coherence tomography (OCT) images because of Henle fiber layer (HFL). Improved differentiation of the ONL and HFL boundary is made possible by using Directional OCT (D-OCT), a method that purposefully varies the pupil entrance position of the OCT beam. Methods Fifty-seven normal eyes were imaged using multiple pupil entry positions with a commercial SDOCT system. Cross-sectional image sets were registered to each other, and segmented at the top of HFL, the border of HFL and the ONL and at the external limiting membrane. Thicknesses of the ONL and HFL were measured and analyzed. Results The true ONL and HFL thicknesses varied substantially by eccentricity and between individuals. The true macular ONL thickness comprised an average of 54.6% of measurements that also included HFL. The ONL and HFL thicknesses at specific retinal eccentricities were poorly correlated. Conclusion Accurate ONL and HFL thickness measurements are made possible by the optical contrast of D-OCT. Distinguishing these individual layers can improve clinical trial endpoints and assessment of disease progression.

Plain gut suture was associated with fewer adverse suture reactions when compared with polyglycolic acid and polyglactin 910 and seems to be suitable for sclerotomy closure.

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