Background To explore the role of foveal and parafoveal Müller cells in the morphology and pathophysiology of tractional macular disorders with a mathematical model of mechanical force transmission.
Methods In this retrospective observational study, spectral-domain optical coherence tomography images of tractional lamellar macular holes and patients with myopic foveoschisis were reviewed and analysed with a mathematical model of force transmission. Parafoveal z-shaped Müller cells were modelled as a structure composed of three rigid rods, named R1, R2 and R3. The angle formed between the rods was referred to as θ . R1, R2 and R3 lengths as well as the variation of the angle θ were measured and correlated with best corrected visual acuity (BCVA).
Results In tractional lamellar macular holes, there was a significant reduction of the angle θ towards the foveal centre (p<0.001). By contrast, there were no significant differences in θ in myopic foveoschisis (p=0.570). R2 segments were more vertical in myopic foveoschisis. There was a significant association between lower θ angles at 200 µm temporal and nasal to the fovea and lower BCVA (p<0.001 and p=0.005, respectively). The stiffness of parafoveal Müller cells was predicted to be function of the angle θ , and it grew very rapidly as the θ decreased.
Conclusion Parafoveal Müller cells in the Henle fibre layer may guarantee structural stability of the parafovea by increasing retinal compliance and resistance to mechanical stress. Small values of the angle θ were related to worse BCVA possibly due to damage to Müller cell processes and photoreceptor’s axons.
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Funding J-PH: consultant for Alcon (Fort Wort, TX, USA), Allergan (Dublin, Ireland); DS: consultant for Amgen (Thousand Oaks, CA, USA), consultant and speaker for Bayer (Leverkusen, Germany), consultant and researcher for Genentech (San Francisco, CA, USA), researcher for Heidelberg (Heidelberg, Germany), speaker for Novartis (Basel, Switzerland), consultant, researcher and speaker for Optovue (Freemont, CA, USA), researcher for Regeneron (Tarrytown, NY, USA); MSF: consultant for Novartis (Basel, Switzerland), Alcon (Fort Wort, TX, USA), Bayer (Leverkusen, Germany), Allergan (Dublin, Ireland), Hoffman LaRoche (Basel, Switzerland), Zeiss (Oberkochen, Germany); FB: consultant for Novartis (Basel, Switzerland), Bayer (Leverkusen, Germany); CC: Consultant for Genentech (San Francisco, California, USA), Merck (Whitehouse Station, New Jersey, USA) Janssen Cell Therapy (Raritan, New Jersey, USA); research support from Hoffman LaRoche (Basel, Switzerland). MRR: research grants from Alcon (Fort Wort, TX, USA); DORC (Zuidland, Holland); Baush & Lomb (Rochester, NY, USA); Bayer (Leverkusen, Germany), consultant for Leica (Wetzlar, Germany).
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon request.
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