Review on Ayurvedic Anatomical Concept of Eye i . e . Netra Sharir

Ayurveda is ancient science of health.. It deals with treatment of diseases with medicines as well as Surgical procedures. Ashtang Ayurveda has Kaya (Medicine), Shalya (Surgery), Shalakya (E. N. T. and Ophthalmology) etc. eight branches of Ayurveda. Shalakya (E. N. T. and Ophthalmology) branch has described various Urdhva Jatrugat Vikar and their management with surgery and medicine. Eye i.e. Netra has its own importance in Panch Dnyaneneindriyas. The description of anatomy of eye can be traced in Vedic literature. The divine Vaidya Ashwinidwaya used to perform eye surgeries with thorough knowledge of anatomy. Vedas are mankind’s source of knowledge. Ayurved is derived from one of the Vedic Samhita called Atharv-ved. One of the eight branches of the Ayurveda is shalakyatantra which deals with diseases of urdhvajatrugatarogas and treatment including surgical one. Father of surgery Sushrutacharya has described eye anatomy in detail in Sushrut Samhita.


Introduction:
The description of anatomy of eye can be traced in Vedic literature. The divine Vaidya Ashwinidwaya used to perform eye surgeries with thorough knowledge of anatomy. Vedas are mankind's source of knowledge. Ayurved is derived from one of the Vedic Samhita called Atharv-ved. One of the eight branches of the Ayurveda is shalakyatantra which deals with diseases of urdhvajatrugatarogas and treatment including surgical one. Father of surgery Sushrutacharya has described eye anatomy in detail in Sushrut Samhita.

Aims and Objects:
To evaluate the importance of Netra sharir in shalya Karma as described in Ayurveda.. The word Drishti is derived from the root'Drus' having meaning to see, when it is sufficed by 'kit karane' meaning source or a tool with which on can see.

Nayana:
This word is derived from root 'ni' heaving meaning to drive or to take away, which when sufficed by 'karanelyut' it becomes Nayana. Nayana is defined as that source drives towards subject of Drishti.

Lochana:
The etymological derivation of lochana is from root√ 'Loch' having meaning to see, which when sufficed by 'KaraneLyut' it becomes Lochana meaning a source with which one can see. Acharya Shushruta and Acharya Vaghbhata have used this word in anatomical sense as synonym of Netra.
Thus from above discussion it is clear that synonyms related to organ of sight i.e. Akshi, Nayana, Netra and lochana are used an anatomical sense while Chakshu is its functional phenomenon whereas drishti is having amphistomous meaning. Netra is widely used word for organ of sight.

Shape:
Two terms are available to the Eye viz. Nayana and Netra in Uttara tantra 1 st chapter, as narrated by Acharya Sushrutha. Both are suggestive as shape. The former means the Eye is like a bubble floating over water i.e. round in shape and soft in consistency, which suggests the external appearance of the eye in the orbit. The later means the Eyeball almost round in shape and resembles the cow's teat.

Dimensions:
Acharya Sushrutha has used Anguli Pramana the unit of measure, in context to the measurement of Eye, it is equal to swangusthodara, which has been given supported and clearly mentioned by the commentator Dalhana that the dimension of this one anguli is equal to the central part of the thumb of an individual.

Circumference:
It is stated that, the thickness or anteroposterior diameter of an eyeball is two anguli, and the circumference i.e. horizontal and vertical diameter two and a half angulas. The distance between two Eyes is two angulas. Measurement of cornea and pupil: lÉå §ÉrÉÉqÉÉÌ §ÉpÉaÉliÉÑ M× üwhÉqÉÇ Qû sÉqÉÑ crÉliÉå | M× üwhÉÉiÉç xÉmiÉqÉÍqÉcNû ÎliÉ SØ Ì¹SÛ Ì¹ÌuÉzÉÉUS: || xÉÑ . E. 1/13 The black part of the eye (krishnamandala / cornea) is said to be one third of its whole extent, while Drishti occupies only one seventh of krishna mandala i.e. iris.
In reference to the description of Eye, Acharya Sushruta has mentioned the following important structures as:

AkshiBandhana:
The Siras, Kandaras, Meda, Kalakasthi and Shleshma are the responsible factors for the proper alignment of the eye. Especially Shleshma, along with siras takes part in the bandhana karma of the eyeballs. Here, Dalhana opines that Sira in the reference includes both the Sira and dhamani and kandara is meant for Snayu and peshi.

Peshi and Snayu:
The Peshis in the eyes are Mandala in shape and are two in number, whereas, the Snayus are of pruthu type and 30 in number.

Marma:
Marma are vital points of the body, trauma to which may result in various complications. Two Marmas mainly Apanga and Avarta are related to Eye. Apangamarma is situated on outer side of the orbits below the lateral end of the eyebrows, ½ angulas in size and is a Sira Marma. AvartaMarma is situated above the lateral end of eyebrow, of same size and Sandhi type of Marma. Any injury to these sites may result in blindness and diminished vision.