IV. Reading comprehension (20%； 2% each)
        There are 160 million people in the United States who wear contact lenses or glasses, many ofwhom are tired of the inconvenience, ongoing expense, and ineffectiveness of prescription lenses. Moreand more Americans, almost 500,000, will have undergone corrective surgery to improve their vision.The surgical process is called LASIK (laser-assisted in situ keratomileusis). The procedure can take lessthan 15 minutes and is performed by an ophthalmologist. The results are impressive, with seven out often people having their vision corrected to 20/20. The majority of the remainder of people could drivewithout the use of corrective lenses. In the future, experts are expecting that the majority of people willsee better than 20/20.         The procedure begins by marking the cornea with ink, then dropping a liquid anesthetic into thepatient’s eye. The ink is water soluble and harmless and is used to help reposition the flaps of thecornea. Then a suction ring stabilizes the eye and pressure is applied to allow for a clean cut by themicrokeratome (the cutting instrument), which glides across the moistened surface of the cornea,cutting the outer layers and stopping automatically. An uncut section acts as a hinge. The attachedcornea is then lifted, and the layers below are excised by the laser. A computer guides the laser as itreshapes the cornea. To correct farsightedness, a piece of tissue shaped like a doughnut ring is removed.If the cornea’s center is trimmed, thereby making it flatter, nearsightedness is corrected. The hingedflap is then put back in position.         While the procedure is effective for the majority of patients, even those with an astigmatism, otherLASIK patients have had problems. A diminishing of contrast has made driving a car more difficult,especially at night. Everyone experiences glare and halo effect in the beginning, but, for some, itbecomes a permanent disability. Also, as people age, most need bifocals for closer work. this is due to acondition called prebyopia (lenses in the eyes lose their ability to curve enough； therefore it is difficultto focus on close objects). LASIK can’t help or prevent this condition.         There are other alternatives being explored to improve vision. INTACS are crescent shaped ringsthat re removable. They are placed within the cornea, leaving it intact. It works well for minimalnearsightedness, but is not effective for extreme nearsightedness, farsightedness, or astigmatism.
       CUSTOM LASIK is adjusted for specific differences in an individual’s cornea, lens, and retina. IT4corrects both nearsightedness (sometimes to 20/20) and farsightedness with or without astigmatism.
The main disadvantage is that it permanently alters the curve of the cornea. INTRAOCULAR lensesare implanted behind the iris or the cornea. These are also removable and leave the cornea in one piece；however, they may cause injury to the cornea, intraocular infection, and cataracts. They are effective forcorrecting both high degrees of nearsightedness and farsightedness.
        Although the risks are small for LASIK surgery, they are real and serious； therefore, one mustconsider the reasons for opting for the surgery. Americans seem to have a penchant for the “cure,” thequick fix, and, as a result, people may rush too quickly for what they see to be a panacea. When itcomes to eye surgery that could possibly cause worse problems than it “cures,” no matter how small therisk, it is wise to explore all of the options.
【題組】29. The cornea is marked with ink in order to ____________
(A) align the suction ring to attach it to the eyeball
(B) determine where the layers below the cornea are to be excised
(C) measure the movement of the eye during surgery
(D) aid in replacing the hinged flaps of the cornea