Maximum visual impairment occurs in:

Nebular corneal opacity has maximal visual disability. Type of corneal opacities Nebular: Superficial layers involving upto superficiial stroma. It do more disability of vision owing to the irregular astigmatism. Macular: Upto mid stroma is involved as opacity Leucomatous: Full thickness stromal opacity. Adherent leucoma is iris tissue incarcerated in opacity, seen normally after perforation. Peripheral, mid peripheral and centrocaecal leucomas will not affect the visual axis and hence would not produce visual disability. However a central leucoma would not allow light to pass through and hence would cause maximum visual problems.