I-Achromatopsia, ebizwa nangokuthi i-achromatia, yisimo esingavamile seso esikuvimbela ukuba ubone imibala. Inomsuka wofuzo ezimweni eziningi, kodwa futhi ingabangelwa ukulimala kwengqondo. Iziguli ezithintekile zibona umhlaba ngombala omnyama nomhlophe.

I-Achromatopsia ibhekisela ekungakwazini komuntu ukubona imibala. Kunamafomu amaningana:

Qedela i-chromatopsia yokuzalwa

Ngenxa yokuguqulwa kwezakhi zofuzo ohlotsheni olulodwa noma ngaphezulu oluhilelekile ekuboneni umbala, i-retina engemuva kweso ayinakho lokho okubizwa ngokuthi amangqamuzana e-photoreceptor “e-cone” ahlukanisa imibala nemininingwane ekukhanyeni. Umphumela: iziguli ezithintekile zibona ngezithunzi ezimpunga. 

Ngaphezu kwalokho, banokuzwela okuphezulu ekukhanyeni kanye ne-acuity ephansi kakhulu ebonakalayo. Konke lokhu kusukela ekuzalweni. Lobu bumpumputhe bemibala buhlotshaniswa nezakhi zofuzo ezishintshashintshayo, buthinta kuphela abantu abanabazali ababili abathwala uguquko olufanayo futhi abaludlulisele kukho. Yingakho ukusabalala kwayo kuphansi, ngokohlelo lwecala elilodwa kubantwana abazalwa abangama-1 kuye kwayi-30 emhlabeni wonke;

I-chromatopsia yokuzalwa eyingxenye noma engaphelele

Leli fomu nalo liwufuzo, kodwa, ngokungafani nelokuqala, lixhunywe ekuguqukeni kwe-X chromosome futhi alithinti zonke izigaxa ze-retina. Ishiya lezo ezizwelayo kuluhlaza okwesibhakabhaka. Yingakho le pathology ibizwa nangokuthi "i-blue cone monochromatism". 

Iziguli ezinayo aziboni okubomvu nokuluhlaza, kodwa zibona okwesibhakabhaka. Ngenxa yokuntuleka kwama-cones anele, ukuqonda kwabo okubonakalayo kubi kakhulu futhi abakwazi ukubekezelela ukukhanya. Njengoba i-chromatopsia engaphelele ihlotshaniswa nokuguquka okuphindaphindekayo okuxhunywe ku-chromosome engu-X, ithinta ngokuyinhloko abafana, abanekhophi eyodwa kuphela yale chromosome (ipheya labo lama-23 lama-chromosome akhiwe ngo-X no-Y ). Njengoba amantombazane enama-X chromosome amabili, kumelwe ukuba azuza njengefa uguquko oluvela kubazali bobabili lube ama-chromats, okuyivelakancane kakhulu;

I-Cerebral achromatopsia 

Akuyona imvelaphi yofuzo. Kubonakala kulandela ukulimala kobuchopho noma ingozi ye-cerebrovascular (stroke) ethinta i-visual cortex. Iziguli ezine-retina evamile futhi ezibone imibala kahle kakhulu kuze kube manje zilahlekelwa leli khono ngokuphelele noma kancane. Ubuchopho babo abusakwazi ukucubungula lolu hlobo lolwazi.

I-Congenital achromatopsia yisifo sofuzo. Izakhi zofuzo eziningana zingabandakanyeka: 

• I-GNAT2 (i-chromosome 1);
• CNGA3 (chromosome 2);
• CNGB3 (chromosome 8);
• I-PDE6C (i-chromosome 10);
• I-PDE6H (i-chromosome 12);
• futhi, esimweni se-blue cone monochromatism, i-OPN1LW ne-OPN1MW (X chromosome). 

Ngenkathi i-congenital achromatopsia izibonakalisa kusukela ekuzalweni, kunezimo ezimbalwa ze-chromatopsia etholiwe. Zibangelwa ukulimala kobuchopho: ukuhlukumezeka noma unhlangothi oluthinta i-visual cortex.

Ezigulini ezinokuguqulwa kwezakhi zofuzo olulodwa noma ngaphezulu, i-retina ayinazo izigaxa ezisivumela ukuba sibone imibala nemininingwane. Anamaseli kuphela "ezindukuni", anomthwalo wemfanelo wokubona ebusuku, emithunzini empunga.

I-Congenital achromatopsia ibonakala nge:

• ubumpumputhe bombala : lokhu kuphelele kuma-chromats aphelele, ababona umhlaba ngokumnyama nokumhlophe, noma cishe ingqikithi kuma-monochromats, abasakwazi ukuhlukanisa okuluhlaza okwesibhakabhaka;
• i-photophobia ephawulekayo, okungukuthi, i-hypersensitivity ekukhanyeni;
• i-acuity encishisiwe yokubuka, phakathi kwe-1/10 ne-2/10;
• un nystagmus, okungukuthi, i-oscillation engavamile, e-jerky ye-eyeball, ikakhulukazi phambi kokukhanya okukhanyayo. Lolu phawu lungase luphele ngokukhula;
• i-central petit scotome, okungukuthi, indawo eyodwa noma ngaphezulu encane phakathi nendawo ebonakalayo.

Lokhu kushoda kukhona kusukela esemncane, kodwa wukungathandi ukukhanya kanye nokunyakaza okungavamile kwamehlo omntwana wabo okuqale kuxwayise abazali, ikakhulukazi uma kukhona ezinye izimo emndenini. Lapho ingane isikhule ngokwanele ukuba iziveze, ukuhlolwa kombala kungenziwa kodwa akwanele, njengoba amanye ama-monochromats ekwazi ukuzivumelanisa nezimo, aze akwazi ukubiza imibala ethile. I-electroretinogram (ERG) kuphela, ekala umsebenzi kagesi wama-photoreceptors ku-retina, engaqinisekisa ukuxilongwa. Ukuhlaziywa kofuzo bese kwenza kube nokwenzeka ukucacisa uguquko okukhulunywa ngalo.

I-Congenital achromatopsia iyi-pathology ezinzile. Nokho, ukonakala okuqhubekayo kwe-macula, okungukuthi, indawo emaphakathi ne-retina, kungase kubonakale kwezinye iziguli, ikakhulukazi njengoba zikhula. 

I-cerebral achromatopsia iwukulahlekelwa okungazelelwe kombono wombala ngemva kokulimala ekhanda noma unhlangothi. 

Okwamanje akukho ukwelashwa kwalesi sifo, kuphela izixazululo zokudambisa izimpawu. Ukungathandi ukukhanya kanye nokuzwela ukugqama ikakhulukazi kungathuthukiswa ngokugqoka izibuko noma amalensi okuxhumana afakwe umbala obomvu noma onsundu, owaziwa ngokuthi "i-chromogenic". Ukukhulisa izibuko ngokukhuliswa okuphezulu kungase kwenze kube lula ukufunda. Kukhona futhi nezinye izinsiza zokukhuthaza ukuzimela kwesiguli: ukuqeqeshwa ku-locomotion, ukulungisa isikhathi sokuthatha izivivinyo zasenyuvesi, njll.

Yebo. Njengoba i-chromatopsia iyisifo sofuzo esikhubaza, ukuxilongwa kwangaphambi kokubeletha kunganikezwa imibhangqwana esengozini, okusho ukuthi emibhangqwaneni lapho bobabili abalingani bengabathwali bezinguquko ezixhumene nalesi sifo. Uma kuwukuguquguquka okufanayo, banamathuba angama-25% okubeletha ingane ene-achromatic.

Endabeni ye-monochromatism, ngumama kuphela ongadlulisela isakhi sofuzo esintula enzalweni yakhe. Uma kungumfana, uzoba achromatic. Uma kuyintombazane, uzoba umthwali wenguquko, njengonina.