tailieunhanh - Refractive Lens Surgery (part 4)

Sau phẫu thuật Một quét và highresolution B-quét đã chỉ ra vị trí chính xác của ống kính để được gần gũi đến độ sâu buồng trước giải phẫu, chứng minh rằng vị trí trục của ống kính không phải là lời giải thích. Trong bất kỳ trường hợp nào, các hằng số lại tính cho ICLs, sử dụng công thức phakic IOL ở trên, kết quả trong ống kính | 62 length underwent full FDA clinical trial lead-ing to its approval in 1998. Data from the overall FDA study showed 76 of cases within 10 degrees 88 within 20 degrees and 95 within 30 degrees of the intended cylindrical axis. The uncorrected visual acuity UCVA of eyes with the STIOL was significantly improved compared to those that received the spherical IOL of similar design. Two years later the FDA went on to designate the STIOL as a new-technology IOL due to its demonstrated improvement of UCVA in astigmatic patients when compared to a spherical IOL. Thereafter the longer TL model was introduced in the lower diopter powers 24 D as a prophylactic against off-axis rotations in these larger myopic eyes. To date both STIOL models have been widely evaluated 34-41 . These reports are quite consistent in demonstrating a predictable improvement in UCVA with the STIOL yet they do differ widely in the occurrence of early off-axis rotation. In 2000 Sun and colleagues 35 36 retrospectively compared 130 eyes that received the Staar AA-4203-TF to 51 eyes that received a spherical IOL with LRI. The STIOL was found to be superior to LRIs in producing UCVA of 20 40 84 vs. 76 as well as in reducing refractive cylinder to D 55 vs. 22 and to D 85 vs. 49 . Twelve eyes 9 underwent STIOL repositioning for off-axis rotation. That same year Ruhswurm used only the toric power STIOL in 37 eyes with a mean preoperative refractive cylinder of D and found 48 to achieve UCVA of 20 40 or better with a reduction of refractive cylinder to D post-operatively 37 . No cases of STIOL rotation greater than 30 degrees were observed although 19 rotated up to 25 degrees. One year later Leyland s group used vector analysis software to calculate the magnitude of expected correction produced by the STI-OL in 22 eyes 38 . The group achieved 73 of the planned reduction of astigmatism including the 18 of cases that experienced off-axis rotation by more than 30 degrees. In a