Keloysius Mak

Non-Myopic Eye  Light converges on the retina, producing a clear and sharp image

Myopic Eye  Light converges before the retina, thus the image formed on the retina is blurred

Myopic Eye  If the cornea is too curved, or if the eyeball too broad, light rays from distant objects converge in front of the retina. This makes objects seem fuzzy or blurred.  Nearby objects don't look blurred because the light rays enter the eye at a slight angle. This means they focus on the retina properly.

What can be done?  Glasses  LASIK

Glasses  For nearsightedness, the glasses offer a concave lens that bends light rays outward, which normalizes the eyeball.  For farsightedness, the glasses use a convex lens that bends the light inward before it reaches the eye's lens, thereby correcting vision.

LASIK procedure  The patient receives topical anesthesia, and if desired a mild sedative - however, the patient is awake during the procedure. 1. Cleansing of the eyelid area, then paper taping the eyelashes to prevent infection. 2. A portable device called a speculum is positioned in the eye to prevent blinking. A suction ring is then placed on the eye, and a momentary blackness occurs. 3. An instrument called a microkeratome glides across the top layer of the cornea, making a thin incision - and creating a flap of tissue. 4. The physician lifts back this flap, then proceeds to position the laser and directs the laser energy. The patient will hear a series of pulses as the laser reshapes the cornea.

Why LASIK  Sophisticated technology has made LASIK a fast, virtually painless and very popular procedure. By 2001, over 2 million people world-wide had chosen LASIK for vision correction.

LASIK Dangers  NONE!

Advantages of rigid lenses  Gas-permeable rigid lenses have several advantages over soft lenses:  Visual acuity is better, especially in the persons with corneal astigmatism.  Allergic or toxic reactions to lens care solutions are less frequent.  Gas-permeable lenses last longer because they are more durable than soft lenses.  The cost of these lenses is usually less because of the longer lens life and lower cost of the material.

Why Rigid Lenses?  Correction of refractive errors such as myopia (nearsightedness)  Prescribed to patients who have suffered trauma to the cornea or who have corneal diseases such as keratoconus.

Why Rigid Lenses are bad  Inability to transmit oxygen from the air to the cornea. Risk of corneal swelling Other complications

Electronic Bifocals  The new glasses could benefit people suffering from presbyopia, a condition in which faraway objects are in focus but those nearby appear blurry.  Spectacles that change prescriptions with the flick of a switch.

Future Glasses : TV Glasses  Light-guide Optical Element (LOE) technology, which sends an image through a lens as thin as 3mm. The result is a personal display that looks like ordinary eyeglasses but provides the wearer with a virtual large-screen television.