article published yes Florianne E Schoot Uiterkamp author 3526230C-F248-11E8-B48F-1D18A9856A87 Margaret E Maes author 3838F452-F248-11E8-B48F-1D18A9856A870000-0001-9642-1085 Mohammad Alamalhoda author Arsalan Firoozi author Gloria Colombo author 3483CF6C-F248-11E8-B48F-1D18A9856A870000-0001-9434-8902 Sandra Siegert author 36ACD32E-F248-11E8-B48F-1D18A9856A870000-0001-8635-0877 SaSi department Dissecting the morpho-functional relationship of microglia project FWF Open Access Fund project Purpose: Optic nerve crush (ONC) is a model for studying optic nerve trauma. Unilateral ONC induces massive retinal ganglion cell (RGC) degeneration in the affected eye, leading to vision loss within a month. A common assumption has been that the non-injured contralateral eye is unaffected due to the minimal retino-retinal projections of the RGCs at the chiasm. Yet, recently, microglia, the brain-resident macrophages, have shown a responsive phenotype in the contralateral eye after ONC. Whether RGC loss accompanies this phenotype is still controversial. Methods: Using the available RGCode algorithm and developing our own RGC-Quant deep-learning-based tool, we quantify RGC's total number and density across the entire retina after ONC. Results: We confirm a short-term microglia response in the contralateral eye after ONC, but this did not affect the microglia number. Furthermore, we cannot confirm the previously reported RGC loss between naïve and contralateral retinas 5 weeks after ONC induction across the commonly used Cx3cr1creERT2 and C57BL6/J mouse models. Neither sex nor the direct comparison of the RGC markers Brn3a and RBPMS, with Brn3a co-labeling, on average, 89% of the RBPMS+-cells, explained this discrepancy, suggesting that the early microglia-responsive phenotype does not have immediate consequences on the RGC number. Conclusions: Our results corroborate that unilateral optic nerve injury elicits a microglial response in the uninjured contralateral eye but without RGC loss. Therefore, the contralateral eye should be treated separately and not as an ONC control. https://research-explorer.ista.ac.at/download/19566/19567/2025_IOVS_SchootUiterkamp.pdf application/pdfno Association for Research in Vision and Ophthalmology2025 eng 1552-5783 4012650710.1167/iovs.66.3.49 663 https://research-explorer.ista.ac.at/record/20467 https://github.com/siegert-lab/RGC-Quant F. E. Miteva, M. E. Maes, M. Alamalhoda, A. Firoozi, G. Colombo, and S. Siegert, “Optic nerve crush does not induce retinal ganglion cell loss in the contralateral eye,” <i>Investigative Ophthalmology &#38; Visual Science</i>, vol. 66, no. 3. Association for Research in Vision and Ophthalmology, 2025. Miteva, F. E., Maes, M. E., Alamalhoda, M., Firoozi, A., Colombo, G., &#38; Siegert, S. (2025). Optic nerve crush does not induce retinal ganglion cell loss in the contralateral eye. <i>Investigative Ophthalmology &#38; Visual Science</i>. Association for Research in Vision and Ophthalmology. <a href="https://doi.org/10.1167/iovs.66.3.49">https://doi.org/10.1167/iovs.66.3.49</a> Miteva, Florianne E., et al. “Optic Nerve Crush Does Not Induce Retinal Ganglion Cell Loss in the Contralateral Eye.” <i>Investigative Ophthalmology &#38; Visual Science</i>, vol. 66, no. 3, 49, Association for Research in Vision and Ophthalmology, 2025, doi:<a href="https://doi.org/10.1167/iovs.66.3.49">10.1167/iovs.66.3.49</a>. Miteva FE, Maes ME, Alamalhoda M, Firoozi A, Colombo G, Siegert S. Optic nerve crush does not induce retinal ganglion cell loss in the contralateral eye. <i>Investigative Ophthalmology &#38; Visual Science</i>. 2025;66(3). doi:<a href="https://doi.org/10.1167/iovs.66.3.49">10.1167/iovs.66.3.49</a> Miteva, Florianne E, Margaret E Maes, Mohammad Alamalhoda, Arsalan Firoozi, Gloria Colombo, and Sandra Siegert. “Optic Nerve Crush Does Not Induce Retinal Ganglion Cell Loss in the Contralateral Eye.” <i>Investigative Ophthalmology &#38; Visual Science</i>. Association for Research in Vision and Ophthalmology, 2025. <a href="https://doi.org/10.1167/iovs.66.3.49">https://doi.org/10.1167/iovs.66.3.49</a>. Miteva FE, Maes ME, Alamalhoda M, Firoozi A, Colombo G, Siegert S. 2025. Optic nerve crush does not induce retinal ganglion cell loss in the contralateral eye. Investigative Ophthalmology &#38; Visual Science. 66(3), 49. F.E. Miteva, M.E. Maes, M. Alamalhoda, A. Firoozi, G. Colombo, S. Siegert, Investigative Ophthalmology &#38; Visual Science 66 (2025). 195662025-04-15T13:40:35Z2026-05-20T06:37:12Z