Yes, above 5-6 diopters is considered high myopia, since that's where the risks for retinal detachment, glaucoma, etc. already increase significantly due to the elongated eyeball.
With high myopia, the vertex distance [0] starts to play a big role. Basically, as an example, if someone needs -10D glasses, the eye just has around -8.75D of myopia [1] (when wearing contact lenses). This gap becomes larger the higher the diopters are.
Using the formula on [0], I think this person has around -46.5D of myopia, but needs -106D glasses due to the vertex distance.
With high myopia, the vertex distance [0] starts to play a big role. Basically, as an example, if someone needs -10D glasses, the eye just has around -8.75D of myopia [1] (when wearing contact lenses). This gap becomes larger the higher the diopters are.
Using the formula on [0], I think this person has around -46.5D of myopia, but needs -106D glasses due to the vertex distance.
[0] https://en.wikipedia.org/wiki/Vertex_distance [1] https://en.wikipedia.org/wiki/Vertex_distance#/media/File:Ve...