153-2012-0258
大家有没有对猫咪眼睛为什么会变色有疑惑？你能相信一只猫能从幼年的蓝色眼睛退掉成为黄色的眼睛，再从黄色的眼睛变成蓝色的眼睛吗？
今天翻译一篇关于眼睛颜色变化的文章。
Kittens’ eyes naturally change from infant blue eyes to the adult colour around 6-8 weeks old, often not reaching their final adult hue for many months. More rarely an adult cat’s eyes change back to blue. In the case of white or white-marked cats, one eye may remain blue – this is congenital heterochromia and is related to the genes that produce white fur.
幼猫出生的时候眼睛是蓝色的，俗称蓝膜，6-8周的时候蓝膜褪去显出眼睛本身的颜色，但需要再过数月才能固定到成猫的眼色度。
但在少数情况下成猫的眼睛会再次变回蓝色。在白色或者加白色的猫种一个眼睛可能一直是蓝色，这是天生的异瞳色，这种现象和产生白色毛发的基因相关。
I can’t find any information on both eyes changing color at the same time, but there is a similar condition in humans called acquired heterochromia iridis where one eye (rarely both) changes color later in life. In humans, loss of eye pigment is often associated with illness or trauma. Because the cat mentioned here has been examined and is healthy, it is more likely that there is a random mutation and the iris has simply stopped producing pigment.
我没有找到两个眼睛同时变色的信息，但两眼变色的情况在人类当中出现过，在人类当中眼睛褪色通常和疾病、外伤有关。不过我们说的是健康的猫咪，他们的眼睛更像是随机突变，虹膜不再产生色素导致的。
Batu is a tawny spotted castrated male Ocicat, born in June 2014. His breeder, Ulla Haapanen, received photos of Batu from his owners, showing that his eye colour has slowly changed within the last year from yellow-green to blue. The gradual change began at the age of 2 years and progressed within a year. By March 2017 he had vivid blue eyes. All five of Batu’s full siblings have normal yellow or green eye colour, as do his parents.
Batu是一个褐色（相当于棕色）斑点虎斑绝育奥西公猫，2014年6月出生，繁育人Ulla Haapanen，收到了Batu主人的照片，照片显示Batu的眼睛在一年的时间里从黄色变成了蓝色。这种渐变行为充2岁开始，持续了大约一年。到2017年3月的时候他的眼睛已经是生动的蓝色了。
Batu眼睛颜色从2016年到2107年的变化
Neither of the cat's parents carry a colourpoint gene and there is no white spotting. Vitiligo (depigmented patches) most usually shows as random white patches on the coat and is not usually symmetrical. Batu's eyes changed from baby-blue to yellow-green in the normal way, but later changed to vivid blue. According to the vet, there’s nothing wrong with Batu. He went to see a vet who specialised in eye diseases. Batu’s intra-ocular pressures were normal (this is not glaucoma), his eyesight is normal, his eyes are completely fine – they are just clear blue instead of yellow-green. Because he is a neuter, it isn’t possible to see if the condition can be passed on genetically.
Batu的父母双方都不带有重点色基因，也没有白斑。白色斑块（褪色补丁）大部分时候显示为毛发上的随机不对称白色斑块，巴图的眼睛从幼年时期的蓝色变成了黄绿色。但是后来变成了生动的蓝色。
兽医说Batu身体没有任何问题。主人去看了眼专科兽医。Batu内眼压完全正常，所以这不青光眼。他的视力也是正常的也是完全正常的，但是他的眼睛是完全的蓝色而不是黄绿色。因为他已经被绝育了，所以已经不可能去证实这种情况能不能传给下一代。
In 2020, Ms. L. Bercand of Gabchaly cattery in France wrote to me about a black female Sphynx whose eyes changed colour at the age of 6 years. Layka was born in Belgium in 2014 and until March 2020 she had gold to green eyes. Since March 2020 her eyes began to change colour, first becoming solid green. In late April Layka started to develop bluish spots in her eyes. In May Layka had totally blue or aquamarine eyes. An ophthalmology specialist confirmed that Layka had no underlying pathology and was in very good shape. In fact nothing in Layka's behaviour has changed. Layka underwent further examinations to look for any pathological abnormalities, but nothing was found.
2020年，法国Gabchaly 猫舍的L.Bercand小姐给我写信，讨论一个黑色的雌性斯芬克斯，他的眼睛在六岁的时候变了颜色。Layka2014年在Belgium出生。直到2020年的三月他的眼睛还是黄色的。2020年3月开始眼睛颜色开始转变，先变成了绿色。在4月末眼睛开始出现蓝色。到五月的时候眼睛已经完全变蓝了。
眼科专家确认Layka的眼睛没有潜在的疾病，Layka的行为也没有任何变化，进一步的医学检查也没有发现任何的异常。
Layka眼睛从黄色变成蓝色
STUDIES INTO LATE EYE COLOUR CHANGE
眼色渐变研究
There is very little information on late eye colour change that isn’t linked to illness. According to “The Color of the Human Eye: A Review of Morphologic Correlates and of Some Conditions that Affect Iridial Pigmentation” (Pascal D. Imesch, MD, Ingolf H.L. Wallow, MD, And Daniel M. Albert, MD in Survey of Ophthalmology Volume 41, Supplement, 2nd February 1997), iris may not remain constant throughout life, but this needs further study. I have excerpted some relevant findings and annotated them with reference to the cats featured on this page.
关于眼睛颜色渐变的资料非常少，即便在人类医学领域这种资料也非常难找，根据“人类眼睛颜色：形态和环境影响虹膜色素的研究（1997年）虹膜可能不会终身一个颜色，但需要深入的研究，我摘取了一些相关的发现用到本文当中。
Differences in eye colour are due to variable amounts of melanin pigment granules within a constant number of melanocytes (melanin producing cells) in the superficial stroma of the iris. These melanocytes reach their genetically determined amount of melanin in early childhood and their melanin content usually remains constant in adulthood. In cats this is when the kitten eye colour changes to the adult eye colour. Except for blue, eye colour depends on the density of melanin granules in the cells. Iris colour is due to either the number and distribution of melanocytes, or to their melanin content, or to a combination of these factors. The number and size of melanin granules, not the number of melanocytes, seems to be the main difference between darker or lighter eye colours. In fact, all eye colours seem to have the same number of melanocytes. Little is known about the regulation of the melanin content. Melanin is derived from tyrosine. The rate of melanin production is controlled by an enzyme called tyrosinase. Metabolism of melanin in the iris usually occurs slowly and is difficult to detect.
眼睛颜色的不同是因为虹膜上生黑色素细胞中黑色素数量决定的。
黑色素生成细胞在猫咪的早期达到基因层面的成熟（包含一定数量的黑色素）。包含色素的数量通常在长大后也不会有变化。
在猫的眼睛当中，从幼猫眼睛颜色换到成猫眼睛颜色后就基本不会再变化了。
除了蓝色，眼睛颜色取决于细胞中黑色素的浓度。虹膜的颜色取决于黑色素生成细胞的数量和分布，或者跟黑色素生成细胞包含的黑色素相关。黑色素的数量和大小，而不是黑色素生成细胞的数量，看起来是深色和浅色眼睛的主要区别因素。
事实上，所有眼睛看起来包含的的黑色素生成细胞的数量是一样的。我们不太知道黑色素的内在组合规则。黑色素是从酪氨酸中生成的。黑色素的生成速率被酪氨酸酶控制。黑色素在虹膜中的代谢通常比较慢也极不容易察觉。
Diseases such as Horner's syndrome and Fuchs' heterochromic iridocyclitis cause a decrease in eye pigmentation in one eye, but not in both. These diseases have other symptoms which weren’t found in these cats. That means something else is going on. It seems that melanin is no longer being produced in the stromal melanocytes, or that melanin is being broken down as fast as it is being produced.
类似于霍纳氏综合征和虹膜睫状体炎等疾病导致一只眼睛的色素降低，而不是两只眼都降低。这些疾病还有其他并发症，但并没有在猫中发现。
这意味着发生了什么。貌似黑色素在黑色素细胞基质中不再被制造了，或者说黑色素被破坏的速度等同被制造的速度。
A study by Carino et al, found that changes in iris colour could occur spontaneously in 10-20% of a normal (human) population until past adolescence. (Carino OB, Matheny AP, DeRousseau CJ, Bito LZ: Changes in iridial pigmentation past childhood through adolescence (abstract). Invest Ophthalmol Vis Sci 35 (Suppl): 1530, 1994)
另一项研究发现虹膜颜色在10-20%的成年人中会发生自发性的改变。
Although eye colour was thought to remain the same (barring trauma or disease), there are some congenital conditions that affect it. Most studies relate to heterochromia, where the eyes are different colours. Laties studied heterochromia in rabbit eyes following sympathectomy (surgical cutting of a sympathetic nerve or removal of a ganglion to block nerve signals) and measured the tyrosinase activity. He also examined the adrenergic innervation of iris melanocytes in different animals, including cats. An adrenergic nerve fibre is a neuron that uses the neurotransmitter adrenaline (epinephrine), noradrenaline or dopamine. Innervate means stimulated by nerve fibres.
尽管眼睛颜色不会轻易发生改变（排除疾病和外伤），但会有些先天因素会影响到眼睛颜色。许多基于异瞳案例，Laties在给兔子做完交感神经切除术后研究兔子的异瞳情况，测量酪氨酸的活跃程度。他也检测不同动物中虹膜黑色素生成细胞的肾上腺素神经分布，包括猫。一个肾上腺神经纤维是一个神经元，用肾上腺素神经递质、去甲肾上腺素或多巴胺。刺激活动的意思是指被神经纤维刺激。
Laties confirmed that melanocytes are closely related to adrenergic innervation. All the sympathectomized rabbits showed a decrease in eye colour and tyrosinase activity in the eye served by the blocked sympathetic nerve. Regulation of the pigment content of stromal iris melanocytes appeared to be influenced by the sympathetic nervous system, even after childhood. (Laties AM: Ocular melanin and the adrenergic innervation to the eye. Trans Am Ophthalmol Soc 72:560-605, 1974). Unlike Laties’ rabbits, the cats on this webpage had colour change in both eyes.
Laties证实生黑色素细胞的活动和肾上腺素活动紧密相关，所有进行过交感神经切除的兔子发生了眼睛褪色和酪氨酸酶活动度下降的现象。虹膜基质生黑色素细胞中的色素调节机制受交感神经系统的影响，即便在幼年以后。
本文是对《LATE EYE COLOUR CHANGE TO BLUE》的翻译整理
原文作者 Sarah Hartwell
翻译人 林枫
