Perspectives and hypothesis from a case of Asymmetric Optic Nerve Drusen.

Purpose A case of bilateral optic nerve head drusen (ONHD), with unilateral VF (VF) defects and Optical coherence tomography (OCT) RNFL (RNFL) loss is presented. Quantification of RNFL and VF loss corresponded to a relative afferent pupillary defect (RAPD). A probable RNFL/VF loss rate of progression was estimated. Case report A healthy 45-year-old female presented with bilateral ONHD. Corrected acuities were OD 20/20-2 and OS 20/20-1. VF was within normal limits OD mean deviation (MD) -1.48 dB, pattern standard deviation (PSD) 1.38 dB), with diffuse defects OS (MD -9.38 dB, PSD 6.65 dB). RNFL values were normal OD, while OS was outside normal limits (average 83 um, superior 90 um, inferior 76 um). A RAPD was observed OS, that corresponded with the magnitude difference between eyes for the VF MD and RNFL. Estimation of rate of progression of RNFL OD assuming a linear rate of loss progression in this ONHD case, predicted approximately an RNFL average/MD VF of 2.65 um/dB loss per year. Conclusion The asymmetric presentation of ONHD in this case provides an indication of the level of loss that may give rise to a RAPD in ONHD. It provides an insight into the possible rate of RNFL/VF loss in ONHD. The measured relative rate of RNFL average to MD VF loss estimated in this case is comparable to that observed in glaucoma optic neuropathy.