Masomphenya 20/20 ndi chiwerengero cha zooneka bwino. 20/20 zooneka bwino zikutanthauza kuti munthu akhoza kuona zinthu zochepa kuchokera pamapazi 20 kutalimodzi ndi munthu yemwe ali ndi maso abwinobwino amakhoza kuwona kuchokera pa mapazi makumi awiri. Ngati munthu ali ndi chidziwitso cha 20/40, amanenedwa kuti awone tsatanetsatane kuchokera pamapazi 20 kutali mofanana ndi munthu yemwe ali ndi maso abwinobwino amakhoza kuchiwona kuchokera mamita 40 kutali.
Katswiri wa ophthalmologist wa ku Dutch, Herman Snellen anapanga zithunzi za Snellen m'chaka cha 1862. Snellen visual acuity imayesedwa ngati kachigawo kakang'ono ndipo amaimiridwa ngati mtunda umene mayeserowo amachitiramo pamtunda umene mbali yochepa kwambiri yomwe imadziwika imapanga mphindi zisanu ndi zisanu tsatanetsatane wa mawotchiwa amachititsa kuti mphindi imodzi ya arc ichitike. Chotsatira ndi kalata yoyenerera, mawonekedwe, chithunzi kapena nambala yogwiritsidwa ntchito kusonyeza nkhani yomwe ikuwonetsedwa bwino.
Masomphenya 20/20 amaonedwa ngati abwino koma sikutanthauza masomphenya abwino. Kukhala ndi masomphenya 20/20 kumangosonyeza kuwona kwa masomphenya patali. Sizinena kanthu za khalidwe la masomphenya ndi luso loyenera kukhala ndi masomphenya abwino monga kuwonetsetsa dzanja la maso, luso lokhala ndi malo ogona, kulingalira kwakukulu, masomphenya owonetsa, kapena masomphenya. Komanso, kukhala ndi masomphenya 20/20 sindikutanthauza kuti diso lako liri labwino. Mmodzi akhoza kukhala ndi glaucoma yoopsa koma amasunga masomphenya 20/20.
Komanso, munthu akhoza kuyang'anitsitsa, komabe amayesa 20/20 zooneka bwino popanda magalasi. Nthawi zina anthu omwe amatha kuyang'anitsitsa amatha kuganizira mozama ndikupindula ndi kuyang'ana. Komabe, kuigwira komweko kwa nthawi yaitali kumatopetsa ndipo pamapeto pake, masomphenya amawonekera.
Masomphenya 20/20 amawonedwa ngati masomphenya.
N'zotheka kukhala ndi masomphenya opambana kuposa 20/20: kuthamanga kwa diso la munthu popanda zithandizo zooneka (monga mabinoculars) kaŵirikaŵiri kumaganiziridwa kukhala pafupi 20/10 ngakhale anthu owerengeka atalembedwa ali ndi masomphenya 20/5.
Njira Zina Zowonetsera Kuwona Zinthu
"Kulumikiza E" Tchati Chowona Chachiwonetsero - Kodi mumayesa bwanji kuyang'ana kwa munthu yemwe sangathe kuyankhula kapena mwina wamanyazi kulankhula? Gwiritsani ntchito Tchinga E chart ikugwiritsira ntchito mlingo womwewo monga momwe Tchati cha Diso la Snellen Chimaonekera. Komabe, njira zonse zomwe zimagwiritsidwa ntchito pa chithunzichi ndizokulu E koma zimagwiritsidwa ntchito mosiyana. Pachifukwa ichi, munthu amene akuonetsedwa kalata yowerengedwa pa tchati cha maso akhoza kungogwiritsa ntchito zala zake ndikuwonetsa kuti ayesedwe ndi chiyani.
Kuyezetsa Kudzala kwa Mayi - Kuyezetsa kwa TB ndiwonekedwe lachidziwitso cha ana omwe sangathe kuwerenga makalata. Chiyesochi chimagwiritsira ntchito ma optotype: apulo, pentagon, square ndi bwalo. Chiyesocho chimagwiritsa ntchito zizindikiro zomwe zimagwiritsidwa ntchito kotero kuti chiwonetsero cha maso chikhoza kuyesedwa ali wamng'ono kwambiri.
Chati cha Jeger Chakuyang'ana Pakuyang'anitsitsa - Ngati mwakhala mukuyesedwa maso, mwina mwawonetsa tchati cha maso cha Jaeger kuti muyese kuyang'ana pafupi ndi zithunzi zooneka bwino. Tchati cha Jaeger ndi tchati chaching'ono chojambula pamanja chomwe chimasonyeza zolemba za malembo osiyanasiyana.
Mmalo mogwiritsa ntchito mawu a 2/20, chithunzi cha Jeager chimagwiritsa ntchito mizere yosiyanasiyana kuchokera ku J1 mpaka J11. J2 nthawi zambiri amawoneka ngati ofanana ndi 20/20 muyeso. Tsambali nthawi zambiri imayenda pakati pa 12 ndi masentimita 12 kuchokera m'maso mwanu.