Ishadi le-Snellen yamehlo ishadi lokuhlola iso elisetshenziswe ochwepheshe bokunakekelwa kweso ukukala ubuciko bokubukwa, noma ukuthi isiguli singabona kanjani ngaphandle kosizo. UDkt. Hermann Snellen wakhulisa ishadi lokubuka ngo-1862.
Konke NgeShadi Lamaziso Lase-Snellen
Ishadi le-Snellen yamehlo yishadi elijwayelekile, elivamile lezinhlamvu ezinkulu nezincane. Ishadi liqukethe imigqa engu-11 yezinhlamvu ze-block, uqala nencwadi eyodwa enkulu emgqeni ophezulu.
Inani lezinhlamvu emgqeni ngamunye landa ukuhamba ukusuka phezulu kuya phansi. Ubukhulu bezinhlamvu buyancipha kancane kancane, kuvumela izinhlamvu eziningi emgqeni ngamunye olandelayo. Ishadi lendabuko le-Snellen lendabuko kuphela lisebenzisa izinhlamvu ezilandelayo: C, D, E, F, L, O, P, T, noZ.
Ukuhlolwa kwe-Acuity Visual
Uma uhlola ukuqina okubonakalayo, isiguli sigubha iso elilodwa futhi lifunde ngokuzwakalayo izinhlamvu eshadini, kuqala phezulu bese lihambela phansi. Umugqa omncane kakhulu wezinhlamvu isiguli esifunda ngokuchanekile sinquma ubuciko obubonakalayo kweso elingafihliwe. Isivivinyo siphindwa ngenye iso, bese-ke ngamehlo womabili ndawonye. Ukuqina okubonakalayo ngezinye izikhathi kuboniswa njenge- 20/20, noma inombolo efanayo, okusho ukuthi izinhlamvu ezincane kunazo zonke zifundwa ngokunembile eshadini.
Imiphumela
Imiphumela yokuhlolwa kwakho kwe-acuity (ishadi lokufunda) lizonquma ikhwalithi yamehlo akho. Imiphumela yombono wakho (ubuningi) izoboniswa njengengxenyana.
Izingxenyana ziboniswa ngakwesobunxele emgqeni ngamunye bese zikhomba ukuthi ungabona kanjani. Uma ungafunda ngokucacile kumugqa wesihlanu, isibonelo, umbono wakho uzoboniswa njengombono we-20/40; uma ungafunda ngokucacile kumugqa wesikhombisa, umbono wakho uzoboniswa ngo-20/25.
Ukuze uhumushe ukufunda kwakho, cabanga ngezinombolo ezinyaweni.
Ngokwesibonelo, umuntu onomqondo we-20/60 angafunda ngezinyawo ezingu-20 ukuthi umuntu onombono ovamile angafunda kanjani ngamamitha angu-60. Amakamelo okuhlola okwakhiwa kwamanje afakwe amashadi e-eye yokufunda iso, okwenze kube lula ukukhiqiza okuyiqiniso.
Okufanele Ukwazi
Kunezinguqulo eziningana zalesi shadi kubantu, njengezingane ezincane, abangakwazi ukufunda izinhlamvu zamagama. Amanye alawa amashadi akhethekile anezithombe zokukhomba esikhundleni sezinhlamvu zamagama noma izinombolo. E-United States, amaphuzu angu-20/40 noma ngaphezulu adingekayo ukushayela imoto ngaphandle kokusetshenziswa kwamalensi okulungisa. Umbono wesabisa ka 20/200 (noma obi kakhulu) unquma ukuthi umuntu uyimpumputhe ngokomthetho .
Ishadi lesiso le-Snellen lingatholakala futhi lisetshenziswe ku-intanethi ngokunquma izinga lakho lombono.
Qaphela, noma kunjalo, ngoba kungaba yinselele ukuthola imiphumela enembile nezibonisi eziningi ezahlukene nezindinganiso zesikrini ezitholakalayo. Indlela engcono kakhulu yokunquma ubuciko bakho obubukwayo obubonakalayo ukuhlolisiswa kweso okwenziwe ochwepheshe.