Holth believes that couching is indicated when the first eye has been lost from expulsive hemorrhage after extraction. Also, in certain incurably insane persons the operation may be done. Exceptionally, couching may be done because of a dense membranous cataract which cannot be discinded with Knapp's knife and extraction is inadvisable.
Reference: Holth. May couching be indicated to-day? Arch Ophthalmol.1902;31.
A look at the past . . .. Arch Ophthalmol. 2007;125(11):1500. doi:10.1001/archopht.125.11.1500