Couching (ophthalmology)

Couching is the earliest documented form of cataract surgery. It involves dislodging the lens of the eye, thus removing the cloudiness caused by the cataract. Couching was a precursor to modern cataract surgery and pars plana vitrectomy.

History
Cataract surgery by “couching” (lens depression) is one of the oldest surgical procedures. The technique involves using a sharp instrument to push the cloudy lens to the bottom of the eye. Perhaps this procedure is that which is mentioned in the articles of the Code of Hammurabi (ca. 1792–1750 BC) though it is a mere speculation. Sushruta, an ancient Indian surgeon, described the procedure in “Sushruta Samhita, Uttar Tantra”, an Indian medical treatise (800 BC) (Duke-Elder, 1969; Chan, 2010). From then on the procedure was widespread throughout the world. Evidence shows that couching was widely practiced in China, Europe and Africa. After the 19th century AD, with the development of modern cataract surgery (Intra ocular extraction of lens (1748)), couching fell out of fashion, though it is still used in parts of Asia and Africa.

Couching was practised in ancient India and subsequently introduced to other countries by the Indian physician Sushruta (c. 6th century BCE), who described it in his work Sushruta Samhita ("Compendium of Sushruta"); the work's Uttaratantra section describes an operation in which a curved needle was used to push the opaque "phlegmatic matter" in the eye out of the way of vision. The phlegm was then said to be blown out of the nose. The eye would later be soaked with warm, clarified butter and then bandaged. Here is a translation from the original Sanskrit:

"vv. 55–56: Now procedure of surgical operation of ślaiṣmika liṅganāśa (cataract) will be described. It should be taken up (for treatment) if the diseased portion in the pupillary region is not shaped like half moon, sweat drop or pearl: not fixed, uneven and thin in the centre, streaked or variegated and is not found painful or reddish.

vv. 57–61ab: In moderate season, after unction and sudation, the patient should be positioned and held firmly while gazing at his nose steadily. Now the wise surgeon leaving two parts of white circle from the black one towards the outer canthus should open his eyes properly free from vascular network and then with a barley-tipped rod-like instrument held firmly in hand with middle, index and thumb fingers should puncture the natural hole-like point with effort and confidence not below, above or in sides. The left eye should be punctured with right hand and vice-versa. When punctured properly a drop of fluid comes out and also there is some typical sound.

vv. 61bc–64ab: Just after puncturing, the expert should irrigate the eye with breast-milk and foment it from outside with vāta-[wind-]alleviating tender leaves, irrespective of doṣa [defect] being stable or mobile, holding the instrument properly in position. Then the pupillary circle should be scraped with the tip of the instrument while the patient, closing the nostril of the side opposite to the punctured eye, should blow so that kapha [phlegm] located in the region be eliminated.

vv. 64cd–67: When pupillary region becomes clear like cloudless sun and is painless, it should be considered as scraped properly. (If doṣa [defect] cannot be eliminated or it reappears, puncturing is repeated after unction and sudation.) When the sights are seen properly the śalākā [probe] should be removed slowly, eye anointed with ghee and bandaged. Then the patient should lie down in supine position in a peaceful chamber. He should avoid belching, coughing, sneezing, spitting and shaking during the operation and thereafter should observe the restrictions as after intake of sneha [oil].

v. 68: Eye should be washed with vāta-[wind-]alleviating decoctions after every three days and to eliminate fear of (aggravation of) vāyu [wind], it should also be fomented as mentioned before (from outside and mildly).

v. 69: After observing restrictions for ten days in this way, post-operative measures to normalise vision should be employed along with light diet in proper quantity."

Modern use
Couching continues to be popular in some developing countries where modern surgery may be difficult to access or where the population may prefer to rely on traditional treatments. It is commonly practiced in Sub-Saharan Africa. In Mali it remains more popular than modern cataract surgery, despite the fact that the cost of both methods is similar, but with much poorer outcome with couching. In Burkina Faso, a majority of patients were unaware of the causes of cataracts and believed it to be due to fate. It is not performed by ophthalmologists, but rather by local healers or "witch doctors".

Technique
A sharp instrument, such as a thorn or needle, is used to pierce the eye either at the edge of the cornea or the sclera, near the limbus. The opaque lens is pushed downwards, allowing light to enter the eye. Once the patients sees shapes or movement, the procedure is stopped. The patient is left without a lens (aphakic), therefore requiring a powerful positive prescription lens to compensate.

Results
Couching is a largely unsuccessful technique with abysmal outcomes. A minority of patients may regain low or moderate visual acuity, but over 70% are left clinically blind with worse than 20/400 vision. A Nigerian study showed other complications include secondary glaucoma, hyphaema, and optic atrophy. Couching does not compare favourably to modern cataract surgery.