The most frequent cataract type seen in adult Retinitis pigmentosa patient is –
Retinitis pigmentosa is associated with posterior subcapsular cataract (PSC).

"Retinal pigment degenerations such as retinitis pigmentosa , Usher's syndrome and gyrate atrophy are associated with cataract, which are usually subcapsular opacities".

—Yanoff & Duker
PSC
Anterior polar
Cortical
Mixed