I-Astigmatism yenye yezona zifo ezinzima kakhulu ekulungiseni iziphene zembono, kwaye ngelo xesha liqhelekileyo phakathi kwamaqela ahlukeneyo.
I-Astigmatism inokudibaniswa kunye ne-myopia kunye ne-hyperopia, kwaye eyona nto yamkelekileyo kwiimeko ezininzi ilungiswa ngoncedo lweziglasi ezikhethekileyo, iilensi ezihlawulela izidumbu ezibonakalayo.
Ukuba uguqulela intsingiselo yelizwi elithi "astigmatism" ukusuka kwisiLatini, akunzima ukuqonda oko kuthetha ntoni ukungabikho kwegxininiso. Ngenxa yesakhiwo esingalunganga se-cornea okanye i-lens, ukuphazamiseka kwabo kuphazanyiswa, kwaye umfanekiso ogqitywayo ubonakala uphazamiseka.
Iingongoma ze-astigmatism akulula ukuzithabatha, kuba umntu akakwazi ukubona zombini izinto ezikude kunye nedekude, kwaye kuvela ukuba kula maxesha amabini ahlukeneyo yeiglasi afunekayo.
Kuba namhlanje kukho okubizwa ngokuba yi-progresal - bifocals lens zeglasi, ezidibanisa imisebenzi emibini-ukulungiswa kwemiboniso ye-myopia kunye nokujonga.
Indlela yokukhetha iilazi nge-astigmatism?
Ngethuba lokuqala imbono yokudibanisa iindidi ezimbini zeelensi zafika kuBenjamin Franklin, owayenxinekile ngokutshintsha iimbini zombini zeiglasi. Ngomnyaka we-1780 wathatha ii-lens ezimbini ezahlukeneyo kunye nomda, wawasika waza wazifakela kwisakhelo. Indawo ephezulu yayiphethwe yilensi yokujonga phambili, kwaye ivela ngaphantsi kwe- myopia . Le yinyathelo elitsha kwi-ophthalmology - ngoku abantu banethuba lokusebenzisa iiglasi enye ukuxazulula iingxaki ezimbini ngeyodwa. Ewe, ukususela ngo-1780 imeko yatshintshile ngandlela-thile, kwaye iziglasi ziye zaphuculwa, kodwa kanye imbono kaBhenjamin isele ihlala kwindawo ehamba phambili ekudaleni i-bifocals.
Ukukhethwa kweziglasi kunye ne-astigmatism akuyona into elula, ukuphunyezwa ngempumelelo kweziphi izinto ezinokuthi zithathelwe ingqalelo:
- ubudala somguli;
- umlinganiselo we-astigmatism;
- umboniso ngamnye weelensi kunye nokulungiswa kwamazinga ahlukeneyo.
Ngexesha lokusebenza, oogqirha bafumene ukuba izigulane ezine-astigmatism zinzima kakhulu ukuthwala ii-lens zokulungisa - zinentloko, isisu, nentlungu emehlweni. Umdala isigulane, ngakumbi ukuba iilazi ze-bifocal ze-glass ze-sphemprismatic ziza kuphazamisa.
Ngoko ke, ekuqalekeni isigulane sinikwa ukuba sigqoke iilazi ezingayilungisanga ngokupheleleyo imbono, kwaye emva kweenyanga ezimbalwa ziphakamisa ukuba zibeke "i-lens" ezinamandla ezihlawulela iimpazamo ezibonakalayo 100%.
"Iiglasi eziyinkimbinkimbi kunye ne-astigmatism," oogqirha baqonda iilensi ngendawo engavumelekanga. Ekubeni i-cornea kunye ne-lens ayifanelekanga kwesi sifo, ukwenzela ukuba ulungelelanise ukuqonda komfanekiso, kufuneka wenze i-lens ekhethekileyo eya kuhlawulela ukukhubazeka. Nge-astigmatism elula, i-lens ifana ne-oval, kungekhona isigaba -
Ukulungiswa kwe-astigmatism elula
I-lens cylindrical isetyenziselwa ukulungisa i-astigmatism elula, apho ukuphazamiseka kukuphazamiseka kuphela kwi-meridian enye, kwaye kuxhomekeke kulo, kuya kuba nokuqokelela okanye ukusabalalisa. I-lens ye-cylindrical ayifani ngokufanayo kwi-lens yesiqhelo eqhelekileyo, kuba ayiyikukhankanya imisebe ekhanyayo ewela kwi-axis yayo. Ngaloo nto, kuphela imirhumo eyawa yi-perpendicular kwi-axis icatshulwa.
Ukulungiswa kwe-astigmatism enzima
Nge-astigmatism edibeneyo okanye eyinkimbinkimbi, iilensi zamathambo zisetyenzisiweyo, apho iilensi ze-cylindrical and sphrical zidibeneyo. Kule meko, nganye yesicatshulwa sokuchaswa (ahluke) inokwenziwa kwayo.