Ku dar liiska calaamadaha leh ee qaababka kala duwan ee muraayadaha indhaha
Context:Qaabka Loo Sameeyo Muraayadaha Indhaha  Inta badan muraayadaha indhaha waa muraayadaha wareegaya: labada dusha sare ee muraayadaha indhaha waa qeybo ka mid ah dusha sare ee wareega. Dusha sare waxay noqon kartaa mid qoyan (oo ka soo baxaya muraayadda), mid qoyan (oo ku dhex jira muraayadda), ama mid fidsan (flat). Xariiqda isku xirta xarumaha goobaha ka kooban dusha sare ee muraayadda waxaa lagu magacaabaa dhidibka muraayadda. Sida caadiga ah dhidibka lensku wuxuu maraa xarunta jirka ee lenska, sababtoo ah sida loo soo saaray. Muraayadaha indhaha waa la jari karaa ama la shiidi karaa ka dib marka la sameeyo si loo siiyo qaab ama cabir kale. Sidaa darteed dhidibka muraayadda ma mari karo bartamaha muraayadda.  Muraayadaha indhaha ee loo yaqaano 'Toric' ama'spheric-cylindrical' waxay leeyihiin dusha sare oo leh laba radii oo kala duwan oo qalooca ah oo ku yaal laba diyaaradood oo orthogonal ah. Waxay leeyihiin awood diiradeed oo kala duwan oo ku saabsan meridians kala duwan. Tani waxay samaysaa lens astigmatic ah. Tusaale waxaa ah muraayadaha indhaha oo loo isticmaalo in lagu saxo astigmatismka indhaha qof.
Waxyaabaha soo socda ayaa ah qaababka kala duwan ee muraayadaha indhaha: - Qalooca: wuxuu ka soo baxayaa dhexda muraayada indhaha - Qalooca: Qalooca dhexda ah ee muraayadda - Fasalka: muraayadaha indhaha ee fidsan