My sister is 41yo.in 2yrs her myopia get worse from-2, 50to-4, 50.now she has problem with contrast(shops, night).are these symptoms of cataract or rp?

Possible cataract: Rp_ does not change refraction. With increasing myopia at an age when this is usually stable suspect cataract or also some corneal diseases. She should be checked out by her ophthalmologist (not i hope an optometrist).

Cataracts Symptoms: Cataracts (a white lens change): most often due to/made worse by (most common first): aging, genetics predisposition, excessive sun exposure, smoking, diabetes, steroid medication, previous trauma, inflammation, infection in the eye causing inflammation; previous intraocular eye surgery; genetic conditions; congenital; Symptom-glare especially at night; cloudy vision, decreased VA, induced myopia