20/20 chiratidzo ndechiyero chekuona zvakanaka. 20/20 kuonekwa kwakanaka kunoreva kuti munhu anogona kuona zvishoma zvishoma kubva pamamita makumi maviri zvichienderana nemunhu ane maziso anoyevedza angaona kubva pamamita makumi maviri. Kana munhu ane ruzivo rwema 20/40, anonzi aone tsanangudzo kubva pamamita makumi maviri zvichienderana nemunhu ane maziso anowanzoona ari kubva mamita makumi mana kubva ipapo.
ChiDutch ophthalmologist, Herman Snellen akavandudza Snellen kuonekwa kwakanaka muna 1862. Snellen maziso anoonekwa sechikamu chiduku uye inomiririrwa semuganhu apo kuedza kunoitwa pamusoro penharaunda apo chiduku chiduku chiduku chinoratidzwa chinosvika maonero emaminitsi mashanu eArc uye tsanangudzo yeiyo maitiro inoshandisa 1 miniti yeArc. Chinhu chinonyanya kushandiswa, tsamba, mifananidzo, kana nhamba inoshandiswa kuratidzira nyaya iyo inooneka yakajeka.
20/20 chiratidzo chinoonekwa sechinyakare asi hazvireve kuti zvinoreva zvakakwana. Kuva nechiratidzo che20/20 chinongoratidzira kujekesa kwemaonero ari kure. Hazviti chinhu pamusoro pehutano hwemaonero uye unyanzvi dzinoda kuva nemaonero akanaka akadai sekubatana kweziso-maoko, kukwanisa kugadziriswa, kudzika kwekunzwisisa, kuonekwa kwepachivi, kana kuonekwa kwemavara. Uyezve, kuva nemaonero 20/20 hakurevi kuti ziso rako rakanaka. Mumwe anogona kunge ane glaucoma yakaoma asi achiri kuchengetedza 20/20 pakati pekuona.
Uyewo, munhu anogona kutarisa mberi , asi achiri kutarisa 20/20 kuona acuity pasina magirazi. Vanhu vanotarisa dzimwe nguva vane kwanisi yekuisa pfungwa dzavo zvakaoma uye vanobhadhara kuona. Zvisinei, kuichengeta ipapo kwenguva yakareba kunopedza uye pakupedzisira, maonero anova akajeka.
20/20 chiratidzo chinoonekwa sechinhu chinoratidzika.
Zvinokwanisika kuva nechiono chinopfuura 20/20: huwandu hwemaziso evanhu pasina maziso anoburitsa (akadai binoculars) inowanzofungidzirwa kuti iri pakati pe20/10 kunyange zvazvo vanhu vashomanana vakanyora vane 20/5 maonero.
Dzimwe Nzira Dzokuenzanisa Maonero Akanaka
"Kugumburudza E" Chati Chete Chakuona - Unoenzanisa sei kuonekwa kwakanaka kune mumwe munhu asingakwanisi kutaura kana zvichida kunyara kutaura? Kugumburana E chati inoshandisa chiyero chechiyero chechiyero sezvinoitwa Snellen Eye Chart. Zvisinei, zvose zvinyorwa zvinoshandiswa pane chati ndeye E guru asi zvinoratidzwa nenzira dzakasiyana. Muchiitiko ichi, munhu ari kuratidzwa tsamba yaunogona kuverenga pane chati chemaziso anogona kungoshandisa minwe yake uye kuratidza muedzo kuti chinonzi E chinorevei.
LEA Vision Test - Mutevedzeri weKA uri chiratidzo chekuona acuity yakagadzirirwa vana vasingakwanisi kuverenga tsamba. Muedzo unoshandisa maitiro: apulo, pentagon, chikwere uye denderedzwa. Chiyero chinoshandisa zviratidzo izvi zvakajairika kuitira kuti ruzivo rwekuona runogona kuyerwa panguva duku.
Jaeger Chiso Chemaziso Pedyo neChiono - Kana wakave nekuongorora kweziso, iwe ungangodaro wakaratidzwa neJeger chati chemaziso kuti uedze yako pedyo nemifananidzo inooneka. Itafura yeJaer ibati duku rinoshandiswa nemaoko rinoratidza zvigwaro zvemavara zvakasiyana-siyana.
Panzvimbo yekushandisa izwi rokuti 2/20, chati yeJeager inoshandisa chiyero chinobva paJ1 kusvika kuJ11. J2 inowanzoonekwa seyakaenzana nechiyero chema 20/20. Iyo chati inowanzokwira pakati pe12-16 masentimita kubva pameso ako.