When wearing contact lenses for the first time, there is often a momentary foreign body sensation and unstable vision
Many people who wear contact lenses for the first time often feel a foreign body sensation on the lens surface with a little tear spilling out when the lens is put into the eye, and their vision is unstable and unclear.
Although many wearers have certain mental preparations before wearing the lenses, they still inevitably feel the discomfort of the foreign body caused by the contact lens as a "foreign body" entering the eye due to psychological tension. In addition to mental factors, this discomfort is caused by actual objective factors, such as: the temperature of the front surface of the eyeball under normal physiological conditions is about 30~33℃. Contact lenses are usually stored in a cool and ventilated place before being worn. When the lenses are worn, the temperature of the lenses is generally 5~10℃ lower than that of the surface of the eyeball. Therefore, the moment the low-temperature lenses are put into the eyes, the low temperature difference will inevitably cause a cooling stimulation to the sensitive eyes. In addition, the difference between the pH value and osmotic pressure of the original storage solution of the lenses and the tear film, and the 20~22% swelling of the lenses after long-term storage, can cause the curvature of the lenses to flatten to a certain extent and increase in diameter. The existence of these factors will cause the eyes to have a short-term mechanical, temperature, pH value, and osmotic pressure stimulation when the lenses are put into the eyes, causing the eyes to have a momentary foreign body sensation and unstable vision, which is inevitable and can be said to be a transient normal reaction. This reaction is relieved as the wearer's mental tension and the lens is retained in the eye for a longer time. After the eye stimulation reaches its peak, the sensitive cornea gradually adapts, and the foreign body sensation gradually fades until the cornea is finally blunted, that is, the foreign body discomfort at the beginning of the lens gradually subsides and disappears. This process usually takes about 15 minutes to achieve blunting and feel comfortable and natural, and the vision is stable.
If the foreign body sensation does not subside or disappear for a long time, and the sense of blunting and comfortable vision cannot be achieved in about 15 minutes, it should be considered whether the edge of the lens is unreasonable or has rough edges or the front and back of the lens are inverted. If obvious stimulation, tears, pain, etc. occur, it should be considered whether the lens has brought dirt into the eye, or whether the lens has scratches and damages. In this case, it should be stopped immediately and checked and treated symptomatically in time to maintain healthy eye vision.
