Xingdao He

Theoretical analysis of wavefront aberration caused by treatment decentration and transition zone after custom myopic laser refractive surgery

Purpose To analyze the induced wavefront aberrations caused by treatment decentration and transition zone after custom myopic laser refractive surgery. Setting Refractive Surgery Center, Tianjin Eye Hospital & Eye Institute, Tianjin Medical University, Tianjin, China. Design Cohort study. Methods Wavefront aberration data from potential refractive surgery candidates were used. Based on the preoperative wavefront aberrations, the custom ablation profile was computed. Then, the influence of treatment decentration and especially that of the transition zone on induced wavefront aberrations was studied. The impact of angle mismatch on induced aberrations was analyzed. Results Data from 117 eyes (77 patients) were analyzed. The transition zone played a significant role in the influence of decentration on the induced aberrations in refractive surgery. Induced coma and spherical aberration increased rapidly as the lateral translation increased, and coma was significantly larger than other Zernike aberration terms. The induced aberrations from decentration with oblique incidence in the laser ablation profile were less than in the actual laser ablation process for slight subclinical decentration. The induced aberrations were not closely related to the subclinical unmatched angle from eye cyclotorsion. The induced aberrations from lateral translation were correlated with the position vector. The transition zone was designed to smooth the transition from the optical zone to the untreated cornea, and it mainly dominated induced coma and spherical aberration. Conclusion To achieve the best postoperative visual performance, the effect of the transition zone in refractive surgery should be taken into account, especially for scotopic pupils. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Effect of pupil size on residual wavefront aberration with transition zone after customized laser refractive surgery

The analysis of the change in residual wavefront aberrations after laser refractive surgery is important for the development of visual correction technology. Based on the ablation profile for wavefront-guided refractive surgery including optical zone and transition zone, the effect of pupil size on residual wavefront aberrations was studied. The research revealed that the optical zone to pupil ratio had a significant influence on the residual wavefront aberrations. The residual spherical aberration and coma were obviously larger than other individual Zernike higher-order terms when pupil diameter was larger than the optical zone size, and they increased rapidly as the pupil size increased. In addition, when the ablation zone diameter was kept constant, the residual higher-order aberrations increased rapidly as the blend coefficient increased for a 6 mm or 7 mm pupil. Furthermore, the residual higher-order aberrations with treatment decentration were distinctly larger than those without decentration. In the achievement of the best postoperative visual performance, the design of ablation profile played a crucial role in decrease of the residual wavefront aberrations after refractive surgery, especially optical zone size and the ablation pattern of transition zone.

Evaluation of optical quality in white light from wavefront aberrations for a myopic population of human eyes

Purpose:u2002 To evaluate optical quality in white light for a myopic population by means of some metrics, such as AreaMTF, VSMTF and EE.

Influence of Temperature on the Threshold Value of SBS in Water

In this paper, the threshold value of stimulated Brillouin scattering (SBS) was measured over the temperature range of 10-45°C in liquid water. The experimental results indicate that influence of temperature on the threshold value of SBS is very distinct. The threshold value of SBS decreases with the increase of temperature. On the basis of theory and experiment, the physical mechanism of the temperature dependence of SBS has been analyzed.

Evaluated optical quality from wavefront aberration for some special human eyes

The optical quality for some special human eyes was evaluated from wavefront aberration data. Wavefront aberrations were measured by a ray-tracing wavefront aberrometer. The optical quality was estimated by means of objective and quantitative optical quality metrics of human eyes. The results show that the point spread function patterns and the values of six optical quality metrics vary with the individual eyes or the levels of aberration. The values of PFWc, SRX, AreaMTF and SRMTF increase, as well as the values of RMSs and SM decrease, with the more corrected aberration orders. The great increase of higher-order aberration may be attributed to the pathological changes or refractive surgery, which results in the distinct degeneration of optical quality of human eye.