眼科學概論 眼的結構分為五大部分 : 眼球, 眼瞼, 淚器, 眼窩, 眼肌. 眼球唯一略圓而偏橢圓形的結構, 前後直徑約 22~23 mm. 如圖 : 1
視覺功能 光線 視網膜 ( 錐狀細胞 桿狀細胞 ) 視神經傳導 視交叉 視放射 大腦枕葉 倒立的影像 轉譯成 直立的影像 白天的視覺 vs. 夜晚視覺 瞳孔的調節 辨三原色, 紅, 黃, 藍 色盲. 部分色盲, 完全色盲 2
視力的發育 出生後逐漸增進 雙眼視覺 Binocular Vision 立體視覺 Stereopsis 人類正常視力之發育 : 出生 ~ 一星期 : 0.01~0.02 一星期 ~ 一個月 : 0.05~0.1 一個月 ~ 一歲 : 0.1~0.3 一歲 ~ 三歲 : 0.4~0.8 三歲 ~ 五歲 : 0.8~1.0 五歲 ~ 七歲 : 1.0 3
眼睛檢查 Entrance Tests External Observation 外觀的觀察 Visual Acuity 視力 / pinhole acuity 瞳孔視力 Push-up Amplitude of Accommodation 視力調節輻奏 Dominant Eye 利眼 Interpupillary Distance 瞳孔間距離 Color Vision Pseudoisochromatic plates (PIPs), D-15 test, 需註明是何種測驗 Stereopsis 立體視力, e.g., Randot, Titmus, Bernell, TNO test/ Polaroid or red-green glasses; Frisby Stereotest, Lang Stereotest/ do not need glasses Pupils testing: light and dark condition, check the anisocoria ( 瞳孔大小不等 ) Pupil reflex, swinging flashlight test 4
External Observation 外觀的觀察 觀察雙眼隻眼球位置, 眼裂之對稱性, 眼球是否突出, 眼皮是否腫脹異常 眼瞼緣 : 是否倒睫, 鱗屑狀脫皮, 異物, 分泌腺囊泡, 是否外翻或內捲, 淚孔位置是否正常 結膜 : 觀察有否濾泡 (follicle), 乳突 (papilla), 結石 (lithiasis), 結痂 (cicatrical change), 異常色素沈著, 異物 角膜 : 角膜清澈度, 大小 5
何謂視力 Visual Acuity? To measure the clarity of vision or the ability of the visual system to resolve detail Visual acuity is variable and is affected by many factors, such as: ambient room illumination delayed adaptation to changes in illumination motivation target contrast and time given to respond 6
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Snellen Chart & Landolt Chart EDTRS Type Chart 8
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何謂 Low vision? implies some reduction in visual acuity and/or visual field. There is no national definition of low vision or vision impairment other than legal Blindness. (USA) 13
Legal Blindness: In the US, the best corrected visual acuity in the better eye is less than or equal to 20/200, or if the visual acuity in that eye is better than 20/200, that the visual field is less than or equal to 20 degrees in the widest diameter The better eye is considered the determining factor, it doesn t matter what the acuity or the other eye is 14
I am legally blind without my glasses. --- nonsensical statement Perhaps a more realistic definition based on the traditional method of determining visual acuity would have been best corrected acuity les than 20/100 15
Performance is a more realistic criterion for determining a disability level Low vision can be defined as vision as vision that is not adequate for the patient s needs A significant restriction in visual field regardless of visual acuity, should also quality a person as having low vision 16
Approximately 25% of those who are legally blind, and only about 17% of the newly blind, are estimated to have no useful vision 17
The leading cause of new blindness is probably agerelated retinal degeneration (ARMD) with diabetic retinopathy being a close second and perhaps first for some specific age group. 18
The Most common causes of legal blindness are (as of the 1970s): For all age groups together: 1) glaucoma, 2) age-related macular degeneration 3) cataract 4) optic nerve atrophy 5) diabetic retinopathy 19
For those under age 20: 1) cataract 2) optic nerve atrophy 3) retinopathy of prematurity 20
Hereditary conditions are responsible for almost 15% of legal blindness according to the National Society for the Prevention of Blindness. The most frequent hereditary cause is the group of disorders know as Retinitis Pigmentosa, which accounts for 5% of the prevalence and 3% of the incidence of legal blindness 21
眼壓測量 可分為接觸性與非接觸性 非接觸性眼壓計 (Non-Contact Tonometer) 接觸性眼壓計為世界眼科標準測量 : Goldman Tonometer 一般平均眼壓應為 :16±3 mmhg, 依種族個人而異, 一般認為上限為 22 mmhg, 有時眼壓 22 mmhg 以下也不一定正常, 仍需倚賴其他檢查而定 22
視野 Visual Field 動態視野檢查 (Kinetic Perimetry) 靜態視野檢查 (Static Perimetry) 電腦自動視野計 (Autoperimetry) 23
造成視覺障礙之種類成因與視覺表現情形 簡略列出一些常見的病因 : 早產兒 高近視 角膜病變 : 圓錐角膜, 近視手術後角膜病變 ( 角膜膨突 ectasia), 角膜潰瘍 水晶體 : 白內障 白化症 青光眼 視網膜病變 : 黃斑部病變, 色素上皮細胞沈積症 (Retinitis Pigmentosa), Stargart disease, 糖尿病視網膜病變, 夜盲症 斜視 弱視 低視力 色盲, 色弱 24
眼科疾病對視覺功能造成的限制與影響 視力受損, 閱讀能力侷限, 行動能力差 視野受損 影像變形, 雙影, 頭痛 炫光, 光暈, 刺目 立體視力受損 顏色辨別不清 反差辨別能力降低 25
炫光 (Glare) 的影響 26
視覺限制對於生活重建與定向行動學習的限制與影響 雖然, 神經細胞不可再生, 但.. 剩餘的神經細胞元可以從新分配, 神經纖維可以重新建結 復健與重建 視覺限制 與 視野缺損 的種類, 關聯到定向行動的學習 27
Thank you for your attention! 蘇國禎眼科視光醫師 O.D. 中山醫學大學視光學系助理教授 台南市中正路 75 號 Tel: 06/221-5326 Fax: 06/222-4647 Mobil: 0920-607-605 E-mail: jimmysu8@csmu.edu.tw 28