Many different parameters must be considered when deciding whether a patient is a good candidate for refractive surgery. Refractive error, patient age, corneal pachymetry and topography, scotopic pupil size, and fundus examination as well as the patient's needs and psychological profile are the main criteria for choosing the proper treatment.
For high myopic corrections, surgeons have to choose, according to the patient's preoperative profile, between keratorefractive (surface or intrastromal) and intraocular procedures (phakic intraocular lens [IOL] implantation or clear lens extraction). Possible complications in high myopic corrections after keratorefractive techniques include corneal ectasia, myopic regression, poor quality of vision in scotopic conditions, and haze,1 whereas intraocular procedures, despite better optical results,2 are more invasive and may result in endothelial cell loss and elevated intraocular pressure.3,4
Few comparative studies between implantable contact lens (ICL) and LASIK exist.5"9 Two prospective, randomized clinical trials have been reported8,9; however, follow-up was ^ 3 years. As long-term evaluation is essential for any procedure, we report 9-year follow-up in a patient who participated in a prospective, randomized, comparative clinical study of LASIK and phakic IOL implantation for the correction of high myopia.
A 21-year-old woman presented for refractive surgery evaluation in 1997. Uncorrected visual acuity (UCVA) was count fingers in both eyes. Preoperative best spectacle-corrected visual acuity (BSCVA) was 20/20 with refraction of -9.25 -0.50 X 85 in the right eye and 20/20 with refraction of -9.50 -0.50 X 125 in the left eye. Scotopic pupil size was 6 mm in both eyes. Central corneal thickness was 496 ??? in the right eye and 506 pm in the left eye. Intraocular pressure was 11 mmHg in both eyes. The patient had no family history of keratoconus. Keratometry was 42.29/43.15 in the right eye and 42.39/43.32 in the left eye (Fig). Ophthalmic examination found no anterior or posterior segment abnormality.
The patient was included in a prospective, randomized, comparative clinical study between LASIK and phakic refractive lens implantation. The patient was fully informed of the possible intra- and postoperative complications and gave written consent in accordance with institutional guidelines and the Declaration of Helsinki.
On July 27, 1997, the patient underwent LASIK in the left eye and 1 month later underwent ICL implantation (posterior chamber hydrogel collagen plate phakic IOL; STAAR Collamer ICL [STAAR Surgical AG, Nidau, Switzerland]; ICM 120V2, size 12 mm) in the right eye. The procedures were randomized according to a coin flip.
Figure. Top) Preoperative, middle) 5 -year, and bottom) 9 -year postoperative topographies after left) ICL implantation in the right eye and right) LTVSIK in the left eye.
Laser in situ keratomileusis was performed with the MEL 60 excimer laser (Aesculap M?dit?e, Heroldsberg, Germany) after a nasally hinged flap of 139 pm (intraoperative pachymetry) was made by the Flapmaker microkeratome (Refractive Technologies Ine, Cleveland, Ohio). The attempted correction was ?9.50 D at the 5-mm optical zone, with no transition zone (estimated maximum ablation depth 87 pm), leaving a residual corneal stromal bed thickness of 280 pm.
Lens power calculations were performed by STAAR Surgical AG on the basis of the following variables: 1) manifest and cycloplegic refractions for a vertex distance of 12.0 mm; 2) keratometry; 3) corneal thickness; and 4) anterior chamber depth. The size of the ICL was chosen by STAAR according to the patient's horizontal corneal diameter (white-to-white) measured with a caliper.
Procedures in both eyes were uneventful. At 1-month postoperative follow-up, UCVA was 20/25 (BSCVA 20/20 with -0.25 -1.50 X 160) in the right eye (ICL) and 20/25 (BSCVA 20/20 with -0.25 -1.50 X 115) in the left eye (LASIK). Refraction regression occurred in the first 6 postoperative months in the LASIK eye (UCVA 20/30, BSCVA 20/20 with -1.00 -1.50 X 120), which remained stable for the duration of follow-up. No statistically significant alterations were found regarding the visual acuity or refraction in the ICL eye during follow-up.
Best spectacle-corrected visual acuity was 20/20 in both eyes at all postoperative examinations (no gain or loss of Snellen lines). Slit-lamp and fundus examinations of both eyes were unremarkable. The corneal topographic appearance revealed anatomical stability in both eyes (see Fig).
Binocular vision was not affected by the different surgical procedures (keratorefractive and intraocular). At last follow-up 9 years postoperatively, the patient reported increased overall satisfaction with the eye implanted with the ICL compared to the LASIK eye, due to superior UCVA, stability, and less night vision problems (glare and halos).
Laser in situ keratomileusis and phakic refractive IOL implantation are the most commonly used procedures for the correction of large degrees of ametropia, especially in young patients. In high myopic corrections (> 10.00 D), predictability, efficacy, stability, and safety of LASIK has been reported to be low.10 Moreover the quality of vision is poor due to the need for smaller attempted optical zones,5 the significant decrease in photopic or mesopic contrast sensitivity,11,12 and the increase of spherical aberration3 postoperatively. On the contrary, phakic refractive IOL implantation, despite the potential damage to endothelial cells,3,4 is a theoretically reversible technique, does not affect the natural prolate shape of the cornea, and contrast sensitivity can be preserved or even improved.11,12
In previous comparative studies of the two procedures with follow-up of up to 3 years,8,9 eyes that underwent phakic refractive IOL implantation had better UCVA and more eyes gained BSCVA lines compared with eyes that underwent LASIK. In this report, better UCVA and stability of residual refractive error with less glare and halos were noted in the eye with the ICL compared to the eye treated with LASIK. The more intense night vision problems in the LASIK eye can be explained by the small attempted optical zone of 5 mm (smaller than the patient's scotopic pupil size) and the absence of a transition zone. Overall, the patient preferred the ICL eye due to better stability and quality of vision.
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