In Canasta, Jokers are considered wild cards and can be used to represent any card in the deck. However, once a Joker has been played on the table, it cannot be exchanged for a different card. Players must use the Joker as the card it was originally played as until the end of the round. **

Canasta is a card game that is typically played with two decks of cards and is best suited for four players in partnerships. The objective of the game is to score points by forming melds of cards and laying them down on the table. Players can also pick up and discard cards to improve their hand and ultimately create a "Canasta," which is a meld of seven cards of the same rank. The game is explained to beginners by teaching them the basic rules of forming melds, picking up and discarding cards, and the scoring system. It's important for beginners to understand the different types of melds and the value of each card in order to play effectively. **

If someone runs out of cards in Canasta but has not formed a Canasta, they are not able to continue playing. In Canasta, forming a Canasta is a requirement before going out, so if a player runs out of cards without achieving this, they cannot end the round. The player would have to wait for the other players to finish the round before reshuffling the discard pile and drawing new cards to continue playing. **

No, it is not allowed to discard 3 jokers in Canasta. In the game of Canasta, jokers are considered wild cards and can be used to substitute for any other card to form a meld. However, there are specific rules regarding the number of jokers that can be used in a meld. In most variations of Canasta, a meld can contain a maximum of two jokers, so discarding 3 jokers would not be allowed. **

When a Canasta Joker is placed on the discard pile, it remains there and is available for any player to pick up. However, if a player wants to pick up the discard pile and there is a Canasta Joker on top, they must have two natural cards of the same rank in their hand to be able to pick it up. The Canasta Joker does not affect the value of the discard pile, and the player who picks it up must still follow the usual rules for melding and building their own Canastas. **

Ophthalmology is the branch of medicine that deals with the diagnosis and treatment of eye disorders and diseases. Ophthalmologists are medical doctors who specialize in the medical and surgical care of the eyes. They are trained to provide a wide range of eye care services, including performing eye exams, prescribing corrective lenses, diagnosing and treating eye conditions such as cataracts, glaucoma, and macular degeneration, and performing eye surgeries. Ophthalmology is a crucial field in maintaining and improving the health and function of the eyes. **

The ophthalmologist may use a variety of eye drops depending on the specific condition being treated. Some common eye drops used by ophthalmologists include artificial tears for dry eye, antibiotic or antiviral eye drops for infections, steroid eye drops for inflammation, and dilating eye drops for eye exams. Additionally, ophthalmologists may also prescribe medicated eye drops for conditions such as glaucoma or allergies. It is important to follow the ophthalmologist's instructions for using the prescribed eye drops to ensure proper treatment and care for the eyes. **

During an eye examination at the ophthalmologist, the patient's medical history and any current eye issues are discussed. The ophthalmologist then performs various tests to assess the patient's vision, eye pressure, and overall eye health. This may include using a chart to check visual acuity, examining the eyes with a light, and using special instruments to look at the back of the eye. Based on the results of these tests, the ophthalmologist can diagnose any vision problems or eye conditions and recommend appropriate treatment. **