2016年3月31日 星期四

20/20 vision, vista, retina, acuity, refract, 20/70 vision

The episodes they recount, so often set amid vistas of piercing natural beauty, also tell of the refined recreations and aristocratic rituals of classical Japan. They show the technological change and cultural ferment that arrived in the 19th century. And with astonishing detail, they report on fashions in clothing, hairstyles and décor. Then, to keep things really lively, they give us all this refracted by the theater, with images of Kabuki actors performing stage versions of the Genji tales. 

 《Ars Technica》表示,在登入紀錄中,有346筆的紀錄,螢幕設備解析度為2048x1536,比iPad2高出一倍。而許多傳言指出,具有這麼高解析 度的螢幕,應該就是由蘋果公司研發的「視網膜螢幕」(Retina Display,此螢幕具有肉眼視網膜無法辨識的高解析度)。

visual acuity

Typical Snellen chart used for visual acuity testing.
Visual acuity (VA) is acuteness or clearness of vision, especially for vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain.[1]
Visual acuity is a measure of the spatial resolution of the visual processing system and is usually tested in a manner to optimise and standardise the conditions. To this end black symbols on a white background are used (for maximum contrast) and a sufficient distance allowed to approximate infinity in the way the lens attempts to focus. Twenty feet is essentially infinity from an optical perspective (the difference in optical power required to focus at 20 feet versus infinity is only 0.164 diopters). Whilst in an eye exam lenses of varying powers are used to precisely correct for refractive errors, using a pinhole will largely correct for refractive errors and allow VA to be tested in other circumstances. Letters are normally used (as in the classic Snellen chart) as most people will recognise them but other symbols (such as a letter E facing in different directions) can be used instead.
In the term "20/20 vision" the numerator refers to the distance in feet between the subject and the chart. The denominator is the distance at which the lines that make up those letters would be separated by a visual angle of 1arc minute, which for the lowest line that is read by an eye with no refractive error (or the errors corrected) is usually 20 feet. The metric equivalent is 6/6 vision where the distance is 6 meters. This means that at 20 feet or 6 meters, a typical human eye, able to separate 1 arc minute, can resolve lines with a spacing of about 1.75mm. 20/20 vision can be considered nominal performance for human distance vision; 20/40 vision can be considered half that acuity for distance vision and 20/10 vision would be twice normal acuity. The 20/x number does not directly relate to the eyeglass prescription required to correct vision, because it does not specify the nature of the problem with the lens, only the resulting performance. Instead an eye exam seeks to find the prescription that will provide at least 20/20 vision.[citation needed]

Microsoft Pitches Merger Vision
Microsoft and Yahoo senior executives met Monday in a session intended to let Microsoft present its vision of a combined company.

Professor Jonathan Spence
The 60th anniversary Reith Lectures take China as their subject, and are given by the eminent historian Professor Jonathan Spence.

Each of the lectures will be available after broadcast to listen again or download.

Lecture 1: Confucian Ways
Recorded at the British Library, London, broadcast on 03 June 2008.


Pronunciation: /ˈvɪstə/


  • a pleasing view:sweeping lawns and landscaped vistas
  • a long, narrow view as between rows of trees or buildings, especially one closed by a building or other structure.
  • a mental view of a succession of remembered or anticipated events:vistas of freedom seemed to open ahead of him


mid 17th century: from Italian, literally 'view', from visto 'seen', past participle of vedere 'see', from Latin videre

noun [C]
1 LITERARY a view, especially a splendid view from a high position:
After a hard climb, we were rewarded by a picture-postcard vista of rolling hills under a deep blue summer sky.

2 a possible future action or event that you can imagine:
As leader, he opened up exciting vistas of global co-operation.


━━ n. (木立・町並などを通した狭い)見通し, 眺望; (見通しのきく)通り, 町並; 予想, 展望; 回想.
 Vista・Vision ━━ n. 【商標】ビスタビジョン ((米国で開発されたワイドスクリーンの映画撮影[映写]法)).

這 vision 在企業管理上有許多人稱之為"願景"-- 對於為未來的想像有些信心
如vision statement 詳後補

視力, 視覺, 先見之明, 眼力, 想象力, 幻想, 幻影, 景象
夢見, 想象, 顯示


She has good vision.
He had a vision of himself as a rich businessman.
She really is a vision.


視力, 視覺, 視野
洞察力; 想象力; 眼力
幻象, 夢想, 幻影
美景; 美人; 絕妙的東西
(修辭學的)描述; 電影中的回憶場面, 幻想場面
the field of vision
a person of broad vision
The lady was a lovely vision.

在夢(幻)中看見; 想象; 顯示


beyond one's vision
在視野之外, 看不見的
have vision of
想象到, 幻想
see visions
見幻象, 能預卜未來, 做先知
tunnel vision
狹隘的視野; 井蛙之見

back vision
binocular vision
blurred vision
視力模糊; 視力障礙
brightness vision
chromatic vision
colour vision
data vision
defective colour vision
deuteranomalous vision
dichromation vision
distinct vision
double vision
electric vision
foveal vision
indirect vision
instant vision
瞬間可視圖象, 瞬間接收圖象
mesopic vision
過渡視覺; 黃昏黎明視覺
mesoptic vision
monocular vision
night vision
夜視, 微光攝象電視
normal trichromatic vision
peripheral vision
周圍視覺; 間接視力
photopic vision
亮視覺, 白晝視覺
protanomalous vision
recurrent vision
scotopic vision
暗[夜, 微光]視覺
space vision
spatial vision
split vision
stereoscopic vision
trichromatic vision
twilight vision
underwater vision
Vista V-
yellow vision
vision on sound


Pronunciation: /rɪˈfrakt/
Translate refract | into German


[with object]
  • (of water, air, or glass) make (a ray of light) change direction when it enters at an angle:the rays of light are refracted by the material of the lens
  • measure the focusing characteristics of (an eye) or of the eyes of (someone): when refracting patients an ophthalmologist relies on verbal reports


early 17th century: from Latin refract- 'broken up', from the verb refringere, from re- 'back' + frangere 'to break'

這是yahoo! answer的問答

What is 20/70 vision?

Its a measure of you visual acuity. 20/20 vision means you are seeing at 20 feet what a person with normal vision would see at 20 feet, and your vision is perfect. 20/70 means that what you are seeing at 20 feet is what a person with normal vision would see at 70 feet. The higher the second number, the worse your vision. Example a person with normal 20/20 vision can read a clock on a wall 20 feet away, but for you that same clock looks like it's 70 feet away and is unreadable.

Low Vision
Low vision is the loss of sight that is not correctible with prescription eyeglasses, contact lenses, or surgery. This type of vision loss does not include complete blindness, because there is still some sight and it can sometimes be improved with the use of visual aids.

Low vision includes different degrees of sight loss, from blind spots, poor night vision, and problems with glare to an almost complete loss of sight. The American Optometric Association defines low vision as two categories:

"Partially sighted": the person has visual acuity between 20/70 and 20/200 with conventional prescription lenses.
"Legally blind": the person has visual acuity no better than 20/200 with conventional correction and/or a restricted field of vision less than 20 degrees wide.
The ratio measurement of vision describes visual acuity, or the sharpness of vision, at 20 feet from an object. For example, having 20/70 vision means that you must be at 20 feet to see what a person with normal vision can see at 70 feet.

Anyone can be affected by low vision because it results from a variety of conditions and injuries. Because of age-related disorders like macular degeneration, glaucoma, and cataracts, low vision is more common in adults over age 45, and even more common in adults over age 75. For example, one in six adults over age 45 has low vision; one in four adults over age 75 has low vision.

The most common types of low vision include:

Loss of central vision: There is a blind spot in the center of one’s vision.
Loss of peripheral (side) vision: Inability to see anything to either side, above or below eye level. Central vision, however remains intact.
Night blindness: The inability to see in poorly lit areas such as a theater, as well as outside at night
Blurred vision: Objects both near and far appear out of focus.
Hazy vision: The entire field of vision appears to be covered with a film or glare.
What causes low vision?
There may be one or more causes of low vision. These are usually the result of disorders or injuries affecting the eye or a disorder such as diabetes that affects the entire body. Some of the most common causes of low vision include age-related macular degeneration, diabetes, and cataracts. Low vision may also result from cancer of the eye, albinism, or a brain injury. If you have these disorders or are at risk for them, you are also at greater risk for low vision.

How is low vision diagnosed?
An eye exam by your eye care specialist can diagnose low vision. You should make an appointment with your eye doctor if your vision difficulties are preventing you from daily activities like travel, cooking, work, and school. The tests the eye doctor will perform include the use of lighting, magnifiers, and special charts to help test visual acuity, depth perception, and visual field.

Can low vision be treated?
Some sight disorders, like diabetic retinopathy, can be treated to restore or maintain vision. When this is not possible, low vision is permanent. However, many people with low vision find visual aids helpful. Popular low vision aids include:

Telescopic glasses
Lenses that filter light
Magnifying glasses
Hand magnifiers
Closed-circuit television
Reading prisms
Non-optical aids designed for people with low vision are also very helpful. Some popular non-optical devices include:

Text reading software
Check guides
High contrast clocks and watches
Talking watches and clocks
Large print publications
Clocks, phones, and watches with enlarged numbers
Visual aids improve both sight and the quality of life for many people. Talk to your doctor about where to purchase visual aids.

Can low vision be prevented?
Low vision may be preventable for patients with diabetes and reversible for those whose vision loss is caused by cataracts.