I-Presbyopia yimeko enxulumene neminyaka ekhokelela ekungaboni kakuhle.Idla ngokuvela ngokuthe ngcembe;uya kusokola ukubona incwadi okanye iphephandaba kufutshane kwaye uya kulisusa ngokwemvelo kude nobuso bakho ukuze libonakale ngokucacileyo.
Kwiminyaka engama-40 ubudala, i-crystalline lens ngaphakathi kwamehlo ilahlekelwa ukuguquguquka kwayo.Xa iselula, le lensi ithambile kwaye ibhetyebhetye, itshintsha ngokulula imilo ukuze ikwazi ukujolisa ukukhanya kwiretina.Emva kweminyaka engama-40, i-lens iba ngqongqo ngakumbi, kwaye ayikwazi ukutshintsha imilo ngokulula.Oku kwenza kube nzima ukufunda okanye ukwenza eminye imisebenzi esondeleyo.
Iilensi ze-Bifocal eyeglass ziqulathe amandla eelensi ezimbini ukukunceda ubone izinto kuyo yonke imigama emva kokuba uphulukene namandla okutshintsha ngokwendalo ukugxila kwamehlo akho ngenxa yobudala, ekwabizwa ngokuba yi-presbyopia.Ngenxa yalo msebenzi ukhethekileyo, iilensi ze-bifocal zidla ngokumiselwa kubantu abangaphezulu kweminyaka engama-40 ukunceda ukubuyisela ukuthotywa kwendalo kombono ngenxa yenkqubo yokuguga.
Nokuba sithini na isizathu sokuba ufuna ummiselo wokulungiswa kombono okufutshane, ii-bifocals zonke zisebenza ngendlela efanayo.Inxalenye encinci kwindawo engezantsi yelensi iqulethe amandla afunekayo ukulungisa umbono wakho okufutshane.Ilensi eseleyo iqhelekile yeyombono wakho womgama.Icandelo le-lens elinikelwe kulungiso olusondeleyo-umbono unokuba neemilo ezintathu:
I-Flat Top ithathwa njengenye yeelensi ezininzi ezilula ukuziqhelanisa nazo, kungoko iyeyona isetyenziswa kakhulu kwi-bifocal (FT 28mm kubhekiswa kuyo njengobungakanani obuqhelekileyo).Esi sitayile selensi sesinye sezona zifumaneka lula phantse kuyo nayiphi na indawo ephakathi kwaye kubandakanya neelensi zokuthuthuzela.I-Flat Top isebenzisa ububanzi obupheleleyo becandelo inika umsebenzisi ukufunda okuqinisekileyo kunye nokutshintsha komgama.
Njengoko igama libonisa ukuba i-bifocal engqukuva ingqukuva ezantsi.Ekuqaleni zazenzelwe ukunceda abanxibi ukuba bafikelele kwindawo yokufunda ngokulula ngakumbi.Nangona kunjalo, oku kunciphisa ububanzi bombono osondeleyo okhoyo phezulu kwecandelo.Ngenxa yoko, i-bifocals ejikelezayo ayithandwa kakhulu kune-flat-top bifocals.Icandelo lokufunda lixhaphake kakhulu kwi-28mm.
Ububanzi becandelo le-Blended bifocal yi-28mm.Olu yilo lwelensi luyiyoci-osmetically eyona lens ikhangeleka kakuhle yazo zonke ii-bifocals, ebonisa phantse akukho phawu lwecandelo.Nangona kunjalo, kukho i-1 ukuya kwi-2mm yokudibanisa uluhlu phakathi kwamandla ecandelo kunye nomyalelo we-lens.Olu luhlu lokuxuba lunombono ogqwethekileyo onokuthi ubonakalise ukungaguquki kwezinye izigulane.Nangona kunjalo, ikwayi-lens esetyenziswa kunye nezigulane ezingaguqukiyo kwiilensi eziqhubekayo.