Ingabe Unesifo Sokungakwazi Ukuhlukanisa Imibala?
“Uma ngigqoka, umkami uyahlola ukuthi imibala engiyikhethile iyahambelana yini,” kusho uRodney. “Lapho sidla ekuseni uyangikhethela izithelo ngenxa yokuthi angikwazi ukubona ukuthi zivuthiwe yini. Ngezinye izikhathi emsebenzini angikwazi ukubona ukuthi kufanele ngichofoze kuphi kuyi-computer, ngoba ngokuvamile izinto zihlukaniswa ngemibala. Lapho ngishayela, amarobhothi abomvu naluhlaza ayefana kimi, ngakho ngiyabheka ukuthi isibani esikhanyayo siphezulu noma singezansi yini. Kodwa amarobhothi avundlile wona ayinkinga.”
URODNEY unesifo sokungakwazi ukuhlukanisa imibala. Wazalwa enenkinga ebangela ukuphazamiseka kwe-retina—ulwelwesi olungaphakathi kweso oluzwelayo ekukhanyeni. Akuyena uRodney kuphela onale nkinga, ithinta owesilisa oyedwa kwabangu-12 abaMhlophe nowesifazane oyedwa kwabangu-200.a Njengeningi labantu abanalesi sifo, uRodney uyayibona imibala ehlukahlukene—akaboni omnyama nomhlophe kuphela. Kodwa eminye imibala kuyena ibonakala ngendlela ehlukile kuleyo abanye abantu ababona kahle abayibona ngayo.
Esweni lomuntu, i-retina ngokuvamile inezinhlobo ezintathu zamangqamuzana azwelayo ekukhanyeni amise okwe-cone. Uhlobo ngalunye luthungatha amaza okukhanya ombala ohlukile oyinhloko—oluhlaza okwesibhakabhaka, oluhlaza okotshani, noma obomvu. Ukukhanya okunamaza ahlukene kushukumisa amangqamuzana ahambelana nakho, athumela umyalezo ebushosheni bese umuntu ekwazi ukubona imibala.b Kodwa-ke, kubantu abanesifo sokungakwazi ukuhlukanisa imibala, ikhono la mangqamuzana lokuzwela liba buthaka noma lishintshe, ngakho indlela athungatha ngayo umbala iyahlanekezeleka. Abantu abaningi abanalesi sifo bakuthola kunzima ukuhlukanisa phakathi kombala ophuzi, oluhlaza okotshani, osawolintshi, obomvu nonsundu. Lesi sifo singakwenza kube nzima ukubona isikhunta esiluhlaza esinkweni esinsundu noma kushizi ophuzi noma ukuhlukanisa umuntu onezinwele ezikhanyayo namehlo aluhlaza okwesibhakabhaka kumuntu onezinwele ezibomvu namehlo aluhlaza okotshani. Uma amangqamuzana amehlo omuntu ozwelayo embaleni obomvu ebuthaka kakhulu, imbali ebomvu ingabonakala imnyama. Bambalwa kakhulu abanalesi sifo abangawuboni umbala oluhlaza okwesibhakabhaka.
Isifo Sokungakwazi Ukuhlukanisa Imibala Nezingane
Ukuphazamiseka kwekhono lokubona ngokuvamile kuzuzwa ngofuzo, futhi izingane ezinalesi sifo zivame ukuzivumelanisa nesimo ngokuzenzekelayo. Ngokwesibonelo, ngisho nalapho zingawuboni umehluko phakathi kwemibala ethile, zingase zikwazi ukubona umehluko ekugqameni kwayo futhi ziwuhlobanise namagama imibala ebizwa ngawo. Zingase zifunde nokuhlukanisa izinto ngamaphethini nangendlela ezizwakala ngazo lapho uzithinta esikhundleni sokuhlukanisa ngemibala. Empeleni, izingane eziningi aziqapheli ukuthi zinenkinga phakathi naso sonke isikhathi sokukhula kwazo.
Ngenxa yokuthi ngokuvamile ezikoleni kusetshenziswa amathuluzi okufundisa anemibala, ikakhulukazi emabangeni abaqalayo, abazali nothisha bangase ngephutha bacabange ukuthi ingane inenkinga yokufunda, kuyilapho empeleni inesifo sokungakwazi ukuhlukanisa imibala. Omunye uthisha waze wajezisa umfana oneminyaka emihlanu ngenxa yokudweba umfanekiso onamafu abomvana, abantu abaluhlaza okotshani nezihlahla ezinamaqabunga ansundu. Kumntwana onalesi sifo, le mibala kungenzeka ifanelekile. Ngakho, ngesizathu esihle, ezinye izikhulu zitusa ukuba izingane zihlolwe ikhono lokuhlukanisa imibala.
Nakuba lingekho ikhambi elaziwayo lalesi sifo, asibi sibi njengoba umuntu ekhula futhi asiyandisi ingozi yokuba nezinye izifo zamehlo.c Noma kunjalo, isifo sokungakwazi ukuhlukanisa imibala singabangela ukukhungatheka. Kodwa ngaphansi koMbuso kaNkulunkulu, uJesu Kristu uyosusa yonke iminonjana yokungapheleli kubantu abesaba uNkulunkulu. Ngakho, abantu ababenezinkinga zamehlo zanoma iluphi uhlobo bayobona ukukhazimula okuphelele kwemisebenzi yezandla zikaJehova. Mathewu 15:30, 21; IsAmbulo 21:3, 4.
[Imibhalo yaphansi]
a Zonke izinhlanga zinazo izifo zokungakwazi ukuhlukanisa imibala, kodwa zivame kakhulu kwabaMhlophe.
b Izilwane eziningi ziyakwazi ukuhlukanisa imibala, nakuba indlela eziyibona ngayo ihlukile kweyethu. Ngokwesibonelo, izinja zinezinhlobo ezimbili kuphela zama-cone kuyi-retina—olunye olombala oluhlaza okwesibhakabhaka kanti olunye olombala ophakathi kobomvu noluhlaza okotshani. Ngakolunye uhlangothi, izinyoni ezithile zinezinhlobo ezine zama-cone futhi zingabona umbala o-ultraviolet, abantu abangenakukwazi ukuwubona.
c Ngezinye izikhathi isifo sokungakwazi ukuhlukanisa imibala singabangelwa yizifo ezithile. Uma uqaphela ushintsho ekhonweni lakho lokuhlukanisa imibala usukhulile, kungase kube kuhle ukubona udokotela wamehlo.
[Ibhokisi/Imidwebo ekhasini 18]
Izindlela Zokuhlonza Isifo Sokungakwazi Ukuhlukanisa Imibala
Izindlela zokuhlonza uhlobo lwesifo sokungakwazi ukuhlukanisa imibala nezinga laso kumuntu ngokuvamile zisebenzisa amaphethini amachashazi anemibala ehlukahlukene. Indlela esetshenziswa kabanzi ka-Ishihara inamaphethini ahlukene angaba ngu-38. Ngokwesibonelo, uma ebheka enye yala maphethini okuhlola emini, umuntu obona kahle kufanele abone unombolo 42 no-74 (kwesokunxele), kanti umuntu onenkinga yokubona umbala obomvu noluhlaza okotshani—okuyinkinga evamile—angase angayiboni inombolo engenhla, futhi abone unombolo 21 ngezansi.d
Uma ukuhlola kwembula ukuthi kunenkinga, udokotela wamehlo angase atuse ukuba kwenziwe ukuhlola okwengeziwe kokuthola ukuthi umuntu uzalwe naso yini lesi sifo noma kunenye imbangela.
[Umbhalo waphansi]
d Le midwebo ihloselwe nje ukuba isibonelo. Ukuhlonzwa kwesifo kufanele kwenziwe uchwepheshe oqeqeshiwe.
[Umthombo]
Color test plates on page 18: Reproduced with permission from the Pseudoisochromatic Plate Ishihara Compatible (PIPIC) Color Vision Test 24 Plate Edition by Dr. Terrace L. Waggoner/www.colorvisiontesting.com
[Ibhokisi ekhasini 19]
KUNGANI SIPHATHA ABESILISA NGOKUYINHLOKO?
Izifo zokungakwazi ukuhlukanisa imibala umuntu azalwa nazo zikuma-X chromosome. Abesifazane banama-X chromosome amabii, kanti amadoda aneyodwa engu-X neyodwa engu-Y. Ngakho, uma owesifazane ezalwa enalesi sifo kuyi-X chromosome, cishe isakhi sofuzo esingalimele esikwenye i-chromosome sizosenza singabi namandla, ngakho ikhono lakhe lokubona ngeke liphazamiseke. Kodwa indoda ezalwa inalesi sifo kuyi-X chromosome yayo ayinayo enye i-X chromosome engalungisa umonakalo.
[Umdwebo/Izithombe ekhasini 18]
(Ukuze ubone ukuthi indaba ihlelwe kanjani, bheka encwadini)
INDLELA ESIBONA NGAYO IMIBALA
Ukukhanya okusuka ezintweni kudlula kuyi-cornea nakuyi-lens kuyohlala kuyi-retina
I-cornea
I-lens
I-retina
Isithombe siyahlanekezeleka kodwa ubuchopho busilungise kamuva
Inzwa i-OPTIC NERVE ithumela imiyalezo yalokho esikubonayo ebuchosheni
I-RETINA inamangqamuzana anjengama-cone kanye nama-rod. Esewonke abonisa imibala ephelele
Ama-rod
Ama-cone
AMANGQAMUZANA ANJENGAMA-CONE azwela ukukhanya okubomvu, okuluhlaza okotshani nokuluhlaza okwesibhakabhaka
Obomvu
Oluhlaza okotshani
Oluhlaza okwesibhakabhaka
[Izithombe]
Amehlo abona kahle
Amehlo anenkinga yokuhlukanisa imibala