| Objective:To evaluate the efficacy, safety and clinical application value of calculating ICL length according to the corneal horizontal diameter.Methods:A Staar Visian implantable contact lens(ICL) was implanted in 10 patients(20 eyes) with high myopia. The lens length was calculated according to the corneal horizontal diameter measured by Orbscan II. Patients were followed preoperatively and postoperatively at 1 day,l week,1,3,6,12,24months. Uncorrected visual acuity, best corrected visual acuity, refraction, intraocular pressure, slit-lamp examining, wavefront aberration and ultrasound biomicroscopy(UBM) were observed. All the observations of preoperative following and the last postoperative following were recorded and analyzed using SPSS 16.0 software package.Results:1. Anterior subcapsular cataract was not fond in any eye after surgery; 2. Pigmentary dispersion was observed on the anterior and posterior surface of ICL, but the degrees had no statistical difference; 3. Intraocular pressure changed from 15.95±3.61 mmHg to 15.65±3.10mmHg, there was no significant difference between them(t=0.28,P>0.05); 4. Corneal endothelium-lens(central Section) distance measured by IOL Master postoperatively was 3.240.41mm, and it was not significantly different from 3.24±0.41mm preoperative (t=-1.54, P>0.05) or 3.02±0.24mm measured by UBM postoperatively(t=2.02,P>0.05); 5. Corneal endothelium-ICL(central Section) distance measured by UBM postoperatively was 2.19±0.26mm, and there was no statistical difference compared with Corneal endothelium-lens(central Section) distance measured by UBM; 6. The degree of ICL tilt measured by UBM was 1.33°±1.19°; 7.The percentage of trabecular-iris angle(TIA) larger than 30°, between 21°and 30°, between 11°and 20°, smaller than 10°was 15%,50%,27.5%,7.5% respectively measured by UBM postoperatively; 8. Angle opening distance at points 500 microm (AOD500) measured by UBM postoperatively at four different points where each ICL loop located was 0.58±0.22mm,0.75±0.43mm,0.90±0.33mm,0.59±0.25mm clockwisely, and there was no significant difference among them (F=2.31,P=0.09) 9.The contact distance between iris and ICL measured by UBM postoperatively at four different points where each ICL loop located was 0.58±0.22mm,0.75±0.43mm, 0.90±0.33mm,0.59±0.25mm clockwisely, and there was no significant difference among them (F=2.31,P=0.09). The mean distance was 0.70±0.33mm; 10. ICL-lens peripheral distance measured by UBM postoperatively at four different points where each ICL loop located was 0.29±0.11 mm,0.36±0.25mm,0.36±0.16mm,0.30±0.20mm clockwisely, and there was no significant difference among them (F=0.44,P=0.73), The mean distance was 0.33±0.18mm; 11.The sulcus diameter measured by UBM postoperatively was 11.55±0.69mm, not statistically different from the corneal horizontal diameter(11.87±0.33mm) measured by IOL Master postoperatively (z=1.85, P=0.065). A weak correlation was noted between them(R=0.28); 12. ICL-lens central distance measured by UBM was 0.56±0.17mm. Pearson's correlation coefficient between ICL-lens central distance and corneal horizontal diameter, sulcus diameter, anterior chamber depth(ACD), ICL length was 0.107,0.158,0.036,0.187 respectively. None of them has statistical difference; 13. Pearson's correlation coefficient between ICL length and corneal horizontal diameter was 0.553, which was statistically significant (F=0.925, P=0.011). Pearson's correlation coefficient between ICL length and sulcus diameter was 0.621, which was also statistically significant (F=11.313, P=0.003); 14. After ICL implantation the root mean square(RMS)of total wavefront aberration decreased significantly (P<0.01).The RMS of higher order aberration(HOA) and third-order 3-foil C9 decreased slightly(P>0.05). Third-order coma-like aberration C8 and 3-foil aberration C6 increased slightly (P>0.05).Conclusion:The predictability of calculating ICL length according to the corneal horizontal diameter was proved. Using corneal horizontal diameter to choose ICL length appeared to be an efficient, safe and clinical application valuable method for the correction of myopia.
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