I-bifocal yile lense eneengongoma ezibini, ngokuqhelekileyo ilensi enye yokubukela izinto ezikude, kunye nelensi enye yokujonga izinto ezikufutshane. I-bifocal yaziwa nangokuthi i-lens multi focal lens. UBen Franklin ubizwa ngokuba ngumvelisi we-lential bifalal lens.
Kutheni Unokufuna I-Bifocal
I-Presbyopia: Kunzima ukuyiqonda de uze ufikelele kwilo xesha ebomini bakho, kodwa malunga no-40 ubudala, sihlakulela i- presbyopia .
I-Presbyopia yenza ukuba ukunciphisa kancane kancane ukukwazi ukugxila kwizinto ezikufuphi nokufunda okuprintwayo. Ekuqaleni, abantu babona ubunzima bokufunda kwindawo ezimnyama nokufunda ukushicilelwa kobukhulu bebhotile. Abantu abane-presbyopia bayaqaphela ukuba kunzima ukugxila kumgama ukuya kufutshane. Njengoko ixesha elidlulayo lihamba kwaye lisondela kwiminyaka yobudala engama-42 ukuya ku-45, liqala ukuba yinkinga ebaluleke kakhulu ebomini babo kwaye yonke into abazama ukuyifunda okanye ibhekise kwibala elikufutshane iba nzima kakhulu. Oogqirha abaziqondi kakuhle inkqubo kodwa bakholelwa ukuba i-presbyopia ikhula ngenxa yentlangano (umzimba we-ciliary) ngaphakathi kweso lingasebenzi kwaye i-lens itholakala ngaphakathi kwamehlo ethu, ibe yinto engapheliyo. Isiphumo somvuzo ukungabi namandla okugxila kwizinto ezikufuphi. Impendulo kule ngxaki iwukuba i-optometrist yakho imisele i-bifocal. Kule ngongoma, sidinga inxalenye enye ye-lens ukugxila kumgama kunye nenye inxalenye yokugxila ekufutshane.
Ukungasebenzi ngokufanelekileyo: Abanye abantu badinga i-bifocal ngenxa yendawo yokungasebenzi . Abanye abantwana bahlakulela imeko apho bengakwazi ukugxila ngokulula ukusuka kude ukuya kutsho. Bakhona banokukhathala okukhulu ngelixa bezama ukugcina ingqalelo ekufutshane ngexesha lokufunda okanye ukufunda eklasini.
I-Esotropia yokuhlala: Esinye isizathu sokuba abanye abantwana bembethe i-bifocal ngenxa yeemeko ezibizwa ngokuba yi-esotropia yokuhlala. I-esotropia yokuhlala isinye seendlela eziqhelekileyo zentlobo. Ngokuqhelekileyo, aba bantwana bajonge kakhulu. Aba bantwana bane- esotropia okanye ijongana eliphambili elibangelwa yimizamo yokugxila kwamehlo njengoko bezama ukucacisa kwaye bahlawule ubuchule. Abanayo ukungalingani phakathi kwenkqubo yokuguqula isisu kunye neenkqubo zokugxila. I-bifocal idla ngokunciphisa ingxaki ngokupheleleyo.
Iintlobo zee-Bifocal Lenses
Iilensi ze-Bifocal zifumaneka kwiindidi ezahlukeneyo.
- I-flat-top - I-flat top bifocal inesigaba esincinci esenziwe njengesiqingatha senyanga okanye incwadi "D" kwicala layo. Libekwe kwindawo yangasese nangaphezulu ukuya ngasezantsi kwe-lens. Ngokuxhomekeka kwintetho, isigulane sinokukhetha phakathi kwesigaba se-25 mm okanye isigaba se-28 mm. Umphezulu wecandelo unomgca obonakalayo kwiseli.
- I-Round seg - I-bifocal ejikelezayo iyingxenye ye-22 okanye ye-24 yeenxa zonke ezantsi kwelo lensi. Le nxalenye ye-bifocal yaphuhliswa ukuze ivumele umntu onxibayo ukuba afumane indawo yokufunda yecandelo elincinci lula. Iziqendu ezijikelezayo aziqhelekanga njengamhlanje.
- I-Blended - i-bifocals edibeneyo yayithandwayo ngaphambi kokuba i-bifocals engabikho. Ngokuqhelekileyo zenziwe kwinqanaba elijikelezayo apho imida iyahlanganiswa nayo yonke i-lens. Nangona i-optician eqeqeshiwe ikwazi ukuyibona ngokulula, kwilizwe lonke lingabonakali kangako kunokuba i-flat top bifocal.
- IsiGqeba-IsiGqeba esiLawulayo isiqhelo se-bifocal ngumgca we-bifocal apho isiqingatha esiphambili (umgama) inxalenye ye-lens ihlukaniswe ngokupheleleyo kwisiqingatha esingaphantsi (kufuphi) inxalenye yelensi ene-lens ebonakalayo elula yonke indlela ngaphesheya kwelensi. Ezi zithandwa kakhulu ngabantu abenza umsebenzi omkhulu kunye nedesksi emsebenzini wabo kwaye bacinga ukuba banike ithuba lokugxila kulo. Baye bangathandabuzeki kwiminyaka yamuva ngenxa yendlela engabonakaliyo ehamba yonke indlela ngaphesheya kwelensi. Kwakhona, ootitshala beengcingo bafumene ukuba abantu abazange basebenzise ubuninzi be-lens kwindawo yengingqi kunye nokucinga kunye ne-flat-top bifocal eyenziwa ngokufanayo.
- Inkqubela phambili - Iilensi eziqhubekayo yile lense ukuba unokuva ukupapashwa njengombonakalo ongabonakaliyo, ongagqibekanga okanye ongenawo umgca. Iilensi zephambili zanda ukwanda okanye ukuguqulwa kwamandla okufunda njengoko i-lens iya phezulu ukuya ngasezantsi kwe-lens ngaphandle kwemigca ebonakalayo. Esikhundleni sokuba ne-cut off-off kude ukuya kude, kukho utshintsho olutshanje ngamandla. Iilensi eziqhubekayo kuba zixhaphake ngokukhawuleza kuba zibonisa ukubonakala komntwana.