Optical and visual quality comparison of implantable collamer lens and femtosecond laser assisted laser in situ keratomileusis for high myopia correction

AIM:To compare clinical outcomes and refractive stability of implantable collamer lens(ICL)implantation and femtosecond laser assisted laser in situ keratomileusis(FSLASIK)for high myopia correction.METHODS:The Optical Quality Analysis System(OQAS)was used to evaluate clinical outcomes objectively after operation for high myopia correction.We compared the two procedures in terms of 1-year changes in uncorrected distance visual acuity(UDVA),corrected distance visual acuity(CDVA),safety index,efficacy index,spherical equivalent,modulation transfer function(MTF)cutoff frequency,strehl ratio(SR)and objective scatter index(OSI).RESULTS:At 1 y postoperatively,the safety indices were 1.33±0.27 in ICL group,and 1.17±0.24 in FS-LASIK group.39.58%in the ICL group and 27.59%in the FS-LASIK group gained CDVA in 2 lines or better than that in preoperative CDVA.The efficacy indices were 1.28±0.22 in ICL group,and 1.13±0.26 in FS-LASIK group.The changes of spherical equivalent from 1 wk to 1 y postoperatively was-0.12±0.37 D in ICL group,and-0.79±0.58 D in FS-LASIK group(P<0.05).Spherical equivalent within±0.50 D was achieved in 97.92%in ICL group and 68.97%in FS-LASIK group.MTF cutoff frequency were higher with ICL as compared to FSLASIK(P<0.05)at each postoperative follow-up stage;for postoperative 1 mo later,SR was statistically significant difference between two groups(P<0.05);with no statistically significant difference in OSI between two groups(P>0.05)in postoperative 3 mo later.CONCLUSION:ICL implantation and FS-LASIK procedures both provide good safety and predictability in high myopia correction.ICL implantation provides better clinical outcomes and refractive stability than FS-LASIK.

Effects of age on ocular anterior segment dimensions measured by optical coherence tomography

Background Older subjects tend to have smaller ocular anterior segment. The present study aimed to measure anterior segment dimensions with optical coherence tomography （OCT） and quantitatively assess the effect of age and other factors. Methods Anterior segment OCT images were obtained in normal subjects residing in the greater Los Angeles area. Four line scans were acquired at the 90%, 45%, 0% and 135% meridians of each eye. Computer calipers acquired anterior segment dimensions of corneal diameter, anterior chamber width, corneal vault and anterior chamber depth on OCT images. Measurements from 4 meridians were averaged. Axial length and corneal power were measured by partial coherence interferometry. Univariate and multivariate analyses were performed to assess correlations. Results Sixty-six eyes of 33 normal subjects （aged 22-65 years, 19 Asians, 14 Caucasians） were enrolled. For every 1 year of age, corneal diameter was 0.03：3 mm narrower （P 〈0.01）, anterior chamber width was 0.031 mm narrower （P 〈0.01）, corneal vault was 0.016 mm lower （P 〈0.01）, and anterior chamber depth was 0.025 mm lower （P 〈0.01）. Asian eyes had smaller corneal diameter （P=-0.035） and anterior chamber width （P=0.015） compared with those of Caucasian eyes. Body height showed positive correlation with corneal diameter （0.039 mm per centimeter of height, P 〈0.01） and corneal vault （0.024 mm per centimetre of height, P 〈0.01）. Gender did not have an independent effect on anterior segment dimensions. Conclusions Anterior segment dimensions were smaller in older subjects. Age-related changes may affect the tolerability of long-term implants such as phakic intraocular lens.