在古印度醫學中，眼科是較為發達的專科，據說在公元前五世紀印度已懂得施行白內障手術。在過去醫學史研究中，學者都注意到印度眼科對中國眼科學所帶來的影響。然而，一種治療技術或者一個專科知識體系，從一個文化體系傳入到另一個文化體系，文化的隔閡會造成接受的困難。從唐宋時代史料來看，時人對眼內障的解釋與治療，深受印度醫學影響，唐代以後更將中印醫術融合在一起。本文的目的，藉著探討唐宋時代人對眼內障理解與治療方法，帶出印度眼科知識落實到治療時，如何被中國醫學接受、理解而達致融合的歷程。 在唐代，印度傳入治療眼內障的醫術有三個重點：一是印度眼科醫學知識，記載在一部《龍樹論》的書中，傳入中國。二是「腦脂下流入眼」解釋眼內障的成因。三是治療方法金針撥障術，利用針刺將眼晶體中混濁的部分挑去，治療眼內障。金針撥障術可追溯至東晉時代已傳入，直到唐代才被認識或流行，宋代醫籍則普遍地記述這種技術。 「腦脂下流入眼」解釋眼內障成因，此說在中國傳統醫籍《靈樞》中找到相類似論述，認為眼與腦相連，因而被中國醫學所接受。金針撥障術所使用的方法，同樣被理解為針灸療法，是由黃帝、華佗所傳授的醫療技術。因此，印度醫學知識經改造後，能夠在中國醫學中存活下來。

Ophthalmology was relatively well developed in ancient India, with the earliest known record of cataract surgery being found on a Sanskrit manuscript from the 5th century B.C. Scholars of medical history are well aware of the Indian influence on Chinese ophthalmology. Nevertheless, medical skills or knowledge are not easily passed from one cultural system to another, because cultural differences engender difficulties in acceptance. During the Tang dynasty, China and India had in-depth cultural exchanges, and when Indian medicine was introduced into China it had a great impact on Chinese medicine in terms of both theory and practice. This paper aims to look at how the Indian method of jinzhen bozhang fa 金針撥障法 (couching for cataract) was absorbed, interpreted and integrated into Chinese medicine during the Tang and Song periods. Indian ophthalmologic medicine as introduced to China during the Tang dynasty had three salient features. First1y, Indian ophthalmologic knowledge was transmitted into China in a book known as Longshu Lun 龍樹論. Secondly, the cause of yanneizhang 眼內障 (cataracts) was seen as being naozhi 腦脂 from the brain flowing into the eyes. Thirdly, the jinzhen bozhang fa treatment used a golden needle to cure cataracts. Using this method, physicians applied a needle on the lens itself in order to displace it from the pupil into the vitreous gel. This treatment was well-known during the Tang and Song periods. Chinese physicians eventually came to accept the Indian explanation of the cause of cataracts because there was a similar description of the brain being connected with the eye in the classical medical book Lingshu 靈樞. Likewise, the use of a golden needle to treat cataracts was understood as an acupuncture technique and thus taken to be part of the medical tradition handed down by Huangdi 黃帝 and Huatuo 華陀. In other words, the Indian medical knowledge was accepted because it was able to be reconstructed using Chinese medical concepts.