Comparison of visual effects of FS-LASIK for myopia centered on the coaxially sighted corneal light reflex or the line of sight.

AIM: To compare visual quality after femtosecond laser in situ keratomileusis (FS-LASIK), between the coaxially sighted corneal light reflex (CSCLR) group and conventional ablation line of sight (LOS) group. METHODS: In total, 243 eyes (122 patients) were treated with centration on the CSCLR (visual axis) and 238 eyes (119 patients) treated with centration on the pupil center (LOS). Postoperative outcomes [uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA)], safety index, efficacy index, refractive outcome, ablation center distance from the visual axis, corneal high-order aberrations, subjective discomfort glare and shadowing incidence rate, and contrast sensitivity at 1, 3, and 6mo were measured and compared. RESULTS: The mean age was 27.77±7.1y in the CSCLR group and 26.03±7.70y in the LOS group. Preoperatively, the manifest refraction spherical equivalent (MRSE) was -6.68±2.60 D in the CSCLR group and -6.65±2.68 D in the LOS group. The postoperative UCVA, BSCVA, MRSE (-0.03±0.263 D in the CSCLR group, -0.05±0.265 D in the LOS group), efficacy index (1.04, 1.03), and safety index (1.09, 1.08) were not significantly different between the groups (all P>0.05). In total, 3% lost one line and more of BSCVA in the CSCLR group, as 9% in the LOS group postoperatively (P<0.05). The ablation center deviation was 0.20±0.15 mm from the visual axis (Pentacam system default setting; range, 0-0.75 mm) in the CSCLR group, and 0.43±0.22 mm (range, 0-1.32 mm) in the LOS group (P<0.0001). Statistically significant greater augmentation of total corneal higher-order aberrations (0.15±0.10 µm and 0.20±0.12 µm respectively, P=0.03) and vertical and horizontal coma (P<0.0001) were noted in the LOS group. Subjective discomfort glare and shadowing incidence rates were 8.59% and 17.5% in the CSCLR and LOS groups, respectively (P<0.05). The 1-month postoperative contrast sensitivity visual acuity in the CSCLR group was significantly higher than that in the LOS group on contrast (100%, 25%, 10%) with a dark background, but there was no significant difference between the groups at 3 or 6m. CONCLUSION: Myopic LASIK centered on the CSCLR achieves significantly lower induction of loss of BSCVA, corneal high-order aberrations, and lower risk of subjective discomfort glare and shadowing, and lower decline in early contrast sensitivity by comparison with centration on the LOS, giving advantages in visual quality postoperatively.

Comparison of corneal flap thickness using a FS200 femtosecond laser and a moria SBK microkeratome.

AIM: To evaluate differences in flap thickness resulting from use of an Alcon Wavelight FS200 femtosecond laser and a MORIA SBK microkeratome when making a 110-µm-thick corneal flap and to identify the potential factors that affect corneal flap thickness. METHODS: A prospective case study was performed on 120 eyes of 60 patients who were divided into two groups for LASIK, each group consisting of 60 eyes (30 patients). The corneal flaps were created using an Alcon Wavelight FS200 femtosecond laser or a MORIA SBK microkeratome. The central corneal flap thickness was calculated by subtraction pachymetry. Age, central corneal thickness (CCT), spherical equivalent refraction, mean keratometry, and corneal diameter were recorded preoperatively for analysis. RESULTS: Cutting of all flaps was easily performed without intraoperative complications. In the Alcon Wavelight FS200 femtosecond laser group, the mean right and left corneal flap thicknesses were 114.0±6.6 µm (range: 98-126) and 111.4±7.6 µm (range: 98-122), respectively. The difference (2.6±9.1 µm) in the corneal flap thickness between the right and left eyes was not significant (t=1.59, P=0.12). Stepwise regression analysis indicated that the resulting corneal flap thickness was unrelated to the patient's age, preoperative CCT, spherical equivalent refraction, mean keratometry, or corneal diameter. In the MORIA SBK microkeratome group, the mean right and left corneal flap thicknesses were 110.6±7.4 µm (range: 97-125 µm) and 108.2±6.1 µm (range: 78-123 µm), respectively. The difference in the corneal flap thickness between the right and left eyes (2.4±6.5µm) was not significant (t=2.039, P=0.0506). The corneal flap thickness was positively correlated with the preoperative CCT through stepwise regression analysis (r=0.297, P=0.021). The corneal flap thickness was not related to age, spherical equivalent refraction, mean keratometry, or corneal diameter. The corneal flap thickness was estimated using the following equation: Tflap=67.77+0.076 CCT (F=5.63, P=0.021). CONCLUSION: Both the Alcon Wavelight FS200 femtosecond laser and the MORIA SBK microkeratome produced 110-µm-thick corneal flaps. The central corneal flap thickness was positively correlated with the preoperative CCT in MORIA SBK microkeratome surgery.

[Comparison of cornea flap made by femtosecond laser and microkeratome in laser in situ keratomileusis].

OBJECTIVE: To determine flap thickness variation in 110 µm thickness flap made by FS200 femtosecond laser and sub-Bowman keratomileusis (SBK) microkeratome for studying the potential factors that affect the flap thickness. METHODS: It was a case-control study. Sixty patients were divided into two groups for laser in situ keratomileusis. The corneal flaps were made by using Alcon Wavelight FS200 femtosecond laser or MORIA SBK microkeratome. Central corneal flap thickness was calculated by subtraction pachymetry. Age, central corneal thickness (CCT), spherical equivalent refraction, mean keratometry and corneal diameter were recorded preoperatively for statistics. RESULTS: This study comprised 120 eyes of 60 patients; 60 eyes were treated with each group. In Alcon Wavelight FS200 femtosecond laser group, the mean corneal flap thickness in the right and left eyes was (114.0 ± 6.6) and (111.4 ± 7.6) µm, respectively. The difference in corneal flap thickness between the right eye and the left eye (2.6 ± 9.1) µm was not statistically significant (t = 1.59, P = 0.12). Corneal flap thickness had no relationship with the age, preoperatively CCT, spherical equivalent refraction, corneal curvature and corneal diameter through stepwise regression analysis. In SBK microkeratome group, the mean corneal flap thickness in the right eye and the left eye was (110.6 ± 7.4) and (108.2 ± 6.1) µm respectively. The difference in corneal flap thickness between the right eye and the left eye (2.4 ± 6.6) µm was not statistically significant (t = 2.019, P = 0.054). Corneal flap thickness was positively correlated with preoperative CCT through stepwise regression analysis (r = 0.29, P = 0.021). Corneal flap thickness equaled to 67.77 + 0.076· CCT (F = 5.63, P = 0.021). Corneal flap thickness had no relationship with the age, spherical equivalent refraction, corneal curvature and corneal diameter. CONCLUSIONS: Both FS200 femtosecond laser and SBK microkeratome can be used for making a good 110 µm thickness flap. Central corneal flap thickness was positively correlated with the preoperative CCT using the SBK microkeratome.

[Three kinds of phakic intraocular lens for correction of high myopia].

OBJECTIVE: To evaluate the efficacy, safety and stability of three kinds of phakic intraocular lens implantation for the correction of high myopia. METHODS: This study included 208 eyes of 110 patients with a mean age of 31 years (21 - 53) from December 2003 to December 2009. Angle-supported lens (Phakic 6H, OII) were inserted into 113 eyes, iris-fixated lens (Artisan, OPHTEC) were inserted into 53 eyes and implantable contact lens (ICL) (V4, STAAR) were inserted into 41eyes. The average follow-up time of the three groups were 54.0 months (3 - 72 months), 15.7 months (3 - 24 months) and 7.2 months (3 - 15 months) respectively. RESULTS: At 3 months and 12 months, the efficacy indexes of the three groups were all above 1.00. Only the angle-supported group was followed up to 72 months postoperatively when the efficacy index dropped to 0.85, but still UCVA was 1.0 (20/20) or better in 16% eyes and 0.5 (20/40) or better in 85% eyes. The safety indexes of the three groups were always above 1.00 during the follow up. In the angle-supported group, 46% eyes were within ± 0.50 D of the desired refraction and 68% eyes were within ± 1.00 D at 5 years postoperatively. In the iris-fixated group, 78% eyes were within ± 0.50 D of the desired refraction and 100% eyes were within ± 1.00 D at 1 years postoperatively. In the ICL group, 95% eyes were within ± 0.50 D of the desired refraction and 100% eyes were within ± 1.00 D at 3 months postoperatively. No statistically significant differences were found between preoperative and 3-month postoperative endothelial cell density in the ICL group. Also, there was no statistically significant reduction in endothelial cell density at 1 years in the iris-fixated group. However, when preoperative and 5-year postoperative measurements were compared in the angle-supported group, the total decrease in cell density is statistically significant (t = 9.769, P = 0.000). 16 eyes developed high IOP within 1 month postoperatively which resolved after intervention. In the three groups (angle-supported, iris-fixated and ICL), the most common complications were pupil ovalization, iris atrophy plus pigment dispersion and lens opacification respectively. CONCLUSION: Although phakic IOL implantation is predictable and safe for treatment of high myopia in short-term, the long-term complications should be concerned and treated well.

[Anterior chamber phakic intraocular lens implantation in highly myopic eyes].

OBJECTIVE: To investigate the stability, predictability and safety of angle-supported phakic intraocular lens (IOL) implantation in high myopia. METHODS: Seventy-six myopic eyes of 40 patients treated with anterior chamber angle-supported phakic IOL (Phakic6H) implantation were followed. The average myopia diopter was (-15.89 +/- 3.78) D (-9.50 to -26.25 D) and the best corrected visual acuity (BCVA) was (0.82 +/- 0.20) (0.5 to 1.0). The average follow-up time was 12 months. All the treated eyes were observed for anterior segment changes, uncorrected visual acuity (UCVA), BCVA, refraction, intraocular pressure (IOP) and corneal endothelium preoperatively and postoperatively. All data were analyzed in statistics. RESULTS: One year after the surgery, the average UCVA was (1.00 +/- 0.35) (0.3 to 1.5) and BCVA was (1.18 +/- 0.29) (0.5 to 1.5). The average residual refraction was (-0.40 +/- 0.64) D (-2.00 to +0.50 D). In 96.1% of eyes, the average residual refraction was within +/- 1.0 diopter. The average corneal endothelial count before and one year after the surgery was (3174 +/- 248)/mm(2) and (3067 +/- 320)/mm(2) (P < 0.01) respectively. The intraocular pressure before and one year after the surgery was (16.12 +/- 2.32) mmHg and (15.29 +/- 3.38) mmHg (P < 0.05) respectively. Two patients (4 eyes) complained of halo and glare. One patient's (2 eyes) pupils were oval and another one (2 eyes) showed decentered phakic IOL. Macular hemorrhage occurred in one patient (2 eyes) after eight months of surgery. CONCLUSIONS: Angle-supported phakic IOL implantation is effective for treatment of high myopia and the results are predictable. It deserves further clinical investigation. The effectiveness and safety of this kind of phakic IOL should be further observed for a long period of time.