Tong Zuo

Tianjin Eye Hospital, T’ien-ching-shih, Tianjin Shi, China

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Publications (20)20.42 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: To observe the changes of pathology and ultra- microstructure of corneal lenticules extracted by femtosecond laser small incision lenticule extraction surgery and to investigate instantaneous damage of photodisruption of femtosecond laser to human corneal tissue in vivo. The small incision lenticule extraction surgeries in 25 myopic eyes were performed with Carl Zeiss VisuMax femtosecond laser, and the lenticules were observed by light microscopy, scanning electron microscopy and transmission electron microscopy. Light microscopy showed slight edema in part of the collagen fibers in the cornea lenticule tissue. A thin layer of deep tissue dyeing at the edge of the lenticule was observed on a linear array. In the center of superficial lenticule tissue existed a few bubbles. Under the scanning electron microscope, the anterior surface of the lenticule was found to be relatively smooth, with no obvious tissue bridge. The posterior surface of the lenticule was slightly irregular compared with the anterior surface. Scattered tissue bridges and residual traces of the effect of femtosecond laser photodisruption could be observed. Under the transmission electron microscope, adjacent collagen fiber layers in the corneal lenticule matrix were detected to cross each other regularly, with no breakage of the collagen fibers or separation of the layers. The incision of the collagen fibers on one side of the lenticule was on a linear alinement. It can also be observed that the central part of the lenticule was mildly damaged. However, the stroma cells near the lenticule limbus were severely damaged. Part of the corneal stroma cells were solidified with several shivers, which might be due to the photodisruption. Some of the damaged corneal stroma cells were observed with remnants, while the spaces occupied by part of the corneal cells became fractured. Obvious damage of the femtosecond laser to the corneal tissue at early stage was not observed. At the edge of the area where femtosecond laser focused, there were mild thermal injury and slight structure change. There were not abnormal appearances of the tissue structure at the non-focus area.
    [Zhonghua yan ke za zhi] Chinese journal of ophthalmology 07/2015; 51(7):520-526.
  • Zhiqing Wu · Yan Wang · Lin Zhang · Weili Geng · Ying Jin · Tong Zuo
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    ABSTRACT: To investigate and analyze the characteristic changes of high order aberrations before and after small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK). Prospective study. Thirty-four patients (16 men and 18 women) underwent SMILE, and 28 cases (15 men and 13 women) underwent FS-LASIK, aged 18 to 39 years. Only the right eye was selected to be analyzed from each patient. All patients had conventional and Pentacam examinations preoperatively, and the ocular higher order aberrations were measured with the Hartman-Shack wavefront analyzer before surgery and at 1 month and 3 months postoperatively. The paired t test, independent t test, and Pearson correlation analysis were used to analyze the collected data. At the 1 month after SMILE group, C3(-1), C3(3) (-0.205±0.199, 0.027±0.071) were higher than the FS-LASIK group (0.004±0.316, -0.022±0.104) (t=-3.141, 2.216, P<0.05), for FS-LASIK group Sh, S4, S5, S6, C4(0) (0.609±0.199, 0.403±0.196, 0.117±0.065, 0.092±0.038, 0.343±0.253) were higher than the SMILE group (0.461±0.130, 0.271±0.096, 0.074±0.028, 0.053±0.018, 0.239±0.121) (t=-3.492, -3.461, -3.449, -5.301, -2.103, P<0.05); At the 3rd month of SMILE group, C3(-1) (-0.177±0.175) was higher than the FS-LASIK group (-0.012±0.337) (t=-2.476, P<0.05), In FS-LASIK group, however, the data for Sh, S4, S5, S6, C4(0) (0.626±0.215, 0.421±0.200, 0.108±0.066, 0.082±0.036, 0.393±0.207) were higher than the SMILE group (0.457±0.113, 0.270±0.106, 0.082±0.031, 0.051±0.017, 0.243±0.115) (t=-3.935, -3.788, -2.049, -4.405, -3.576, P<0.05). With the correlation analysis, at the postoperative 1st and 3rd month of FS-LASIK group, Sh, C4(0) had negative relationship with the attempted myopic corrections (1 month post-op: r = -0.433, -0.476, P<0.05; 3 month post-op: r = -0.418, -0.447, P<0.05). SMILE resulted in good optical quality early after operation. Compared with FS-LASIK, SMILE caused smaller change of ocular higher order aberrations, and each of them had its own particularity. Maybe it was associated with the surgery procedure and corneal wound healing after surgery. (Chin J Ophthalmol, 2015, 51: 193-201).
    [Zhonghua yan ke za zhi] Chinese journal of ophthalmology 03/2015; 51(3):193-201.
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    ABSTRACT: To report the clinical results of micro incision lenticule extraction (MILE) to correct myopia or myopia with astigmatism, and enlighten its viability and mechanism. Prospective case-control study. All patients enrolled were treated by the VisuMax femtosecond laser system to correct refractive errors. Sixty-one patients underwent MILE with an incision of 2 mm. Another 53 patients underwent small incision lenticule extraction (SMILE) with a 3-5 mm incision as the control group. All patients took measurements of uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refractive power and intraocular pressure, slit-lamp microscopy, and corneal topography preoperatively and at 1 day, 1 week, 1 month, 6 months postoperatively. The visual acuity was presented as median. To compare the visual acuity and astigmatism between the MILE group and the SMILE group, as well as before surgery and at each time point after surgery, non-parametric tests were applied in this study. The repeated measures analysis of variance was used to compare the differences between these two surgeries and between pre- and post-operation in diopters and morphological parameters. The paired-sample t test was used to compare the diopters and morphological parameters at each time point postoperatively and preoperatively. The independent-sample t test was applied to compare the basic characteristics preoperatively and the diopters, morphological parameters at each time point between these two groups. Forty-one eyes (24 patients) in the MILE group and fifty-one eyes (29 patients) in the SMILE group had complete follow-up data. Before surgery and at 1 day, 1 week, 1 month, 6 months after surgery, the spherical diopters in the MILE group were (-5.09 ± 1.04), (0.12 ± 0.32), (0.11 ± 0.29), (0.02 ± 0.33) and (0.02 ± 0.23) D; the cylinder diopters were (-0.90 ± 0.83), (-0.25 ± 0.27), (-0.23 ± 0.30), (-0.20 ± 0.25) and (-0.16 ± 0.21) D. In the SMILE group, the spherical diopters were (-5.37 ± 1.26), (-0.04 ± 0.49), (0.12 ± 0.38), (0.10 ± 0.34) and (0.02 ± 0.33) D; the cylinder diopters were (-0.76 ± 0.65), (-0.22 ± 0.26), (-0.25 ± 0.30), (-0.26 ± 0.29) and (-0.21 ± 0.28) D. No significant difference was found between the two groups (F = 1.042, 0.941, 0.018; P = 0.310, 0.335, 0.894). In the vector analysis of astigmatism, at 1 month and 6 months after surgery, the values on Y axis were -0.06 ± 0.11 and -0.04 ± 0.10 in the MILE group, smaller than -0.14 ± 0.18 and -0.11 ± 0.16 in the SMILE group (Z = -2.076, -2.149; P = 0.038, 0.032). All full-correction patients had UCVA of 20/20 or better, and no BCVA decreased after 6 month follow-up postoperatively. Refractive stability was achieved within 1 month postoperatively, and less volatility appeared in the MILE group than the SMILE group. Before surgery and at 1 day, 1 week, 1 month, 6 months after surgery, no significant difference in the index of surface variance (ISV) and the index of vertical asymmetry (IVA) was found between the MILE group and the SMILE group (F = 0.902, 0.744; P = 0.345, 0.391), whereas the values of ISV and IVA were smaller in the MILE group than the SMILE group at each time point after surgery, and the D-value between the two groups increased with time. Six cases (9 eyes) had an opaque bubble layer while femtosecond laser passed in the procedure, 2 eyes had a small tear at the incision edge, 1 eye had local diffuse inflammatory exudates at 1 day postoperatively, and no eye had transient light-sensitivity syndrome, decrease of corneal transparency or infection. MILE surgery (1.5-2.0 mm) is safe, predictable, effective and stable to treat refractive errors. It can reduce astigmatism values on oblique axis and maintain the integrality and stability of the structure of the cornea.
    [Zhonghua yan ke za zhi] Chinese journal of ophthalmology 09/2014; 50(9):671-80.
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    ABSTRACT: To evaluate and compare the recovery of central and peripheral corneal sensitivity in the early period after small incision lenticule extraction (SMILE) and femtosecond lenticule extraction (FLEx). In this study, 47 cases (87 eyes) which underwent SMILE and FLEx were included. Central, superior, inferior, nasal and temporal corneal sensitivity was measured using a Cochet-Bonnet esthesiometer (Luneau Ophthalmologie) before and 1 week, 1 month, and 3 months after SMILE and FLEx. The results were analyzed with Mann-Whitney test by SPSS13.0 software. There were statistical differences between SMILE and FLEx group in the central, inferior, nasal and temporal corneal sensitivity at 1 week, 1 month and 3 months postoperatively (Z = -5.219, -7.120, -6.735, -7.139, -5.945, -6.644, -7.006, -7.121, -5.262, -3.086, -4.140, -3.523. P < 0.01). However, the superior corneal sensitivity in the SMILE group did not show significant difference (Z = -1.807, P = 0.071) as compared to FLEx group (with exception of 1 week postoperatively). At 1 month and 3 months postoperatively, corneal sensitivity in the superior quadrant were (5.23 ± 0.62) and (5.57 ± 0.57) cm in the SMILE group, and were (4.43 ± 1.20) and (4.85 ± 1.11) cm in the FLEx group. There were statistical differences between these two groups (Z = -2.935, -2.678. P = 0.003, 0.007). In the SMILE group, corneal sensitivity in the central, superior, inferior, nasal and temporal quadrants at 3 months postoperatively was (5.74 ± 0.51), (5.57 ± 0.57), (5.70 ± 0.55), (5.83 ± 0.37), (5.84 ± 0.30) cm respectively, there were no significant differences as compared with preoperative data (Z = -1.255, -0.893, -0.570, -0.630, -0.935. P = 0.209, 0.440, 0.569, 0.529, 0.350). In the FLEx group, corneal sensitivity in the superior at 3 months postoperatively was 4.85 ± 1.11, there was not significant difference compared with preoperative data (Z = -1.095, P = 0.272). There were no correlations between the changes of central corneal sensitivity and central corneal ablation depth, central corneal thickness and preoperative spherical equivalent (SMILE group: r = 0.159, -0.202, 0.106, 0.060. P > 0.05. FLEx group: r = -0.156, -0.059, 0.058, -0.005. P > 0.05) after SMILE and FLEx surgery. Corneal sensitivity decreases after SMILE and FLEx, and then returns to its original state over time. The decrease of corneal sensitivity after the SMILE was fewer and the recovery was faster as compared with FLEx.
    [Zhonghua yan ke za zhi] Chinese journal of ophthalmology 04/2013; 49(4):299-304.
  • Yan Wang · Xi-Liu Bao · Xin Tang · Tong Zuo · Wei-Li Geng · Ying Jin
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    ABSTRACT: To evaluate the safety, efficacy, predictability, stability and complications of femtosecond laser corneal small incision lenticule extraction (SMILE) procedure for the correction of myopia and myopic astigmatism. In this prospective study, 50 patients (88 eyes) with myopia and myopic astigmatism were chosen to be performed SMILE procedure randomly. These patients were followed up at 1 day, 1 week, 1 month and 3 months postoperatively and were examined for uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest refraction, intraocular pressure (IOP) and corneal topography. The results were analyzed with paired-t test, independent-samples t test and regression analysis. SMILE procedure was performed well in all patients, only 3 cases (3 eyes, 3.4%) suffered from the suction loss, 14 cases (26 eyes, 29.5%) developed opaque bubble layer. All patients gained perfect UCVA (20/20), no eye had decrease of BCVA. The residual spherical equivalent was (-0.11 ± 0.29) D, the astigmatism was (0.01 ± 0.33) D 3 months postoperatively. The incidence of diffuse lamellar keratitis and haze was low, and no other complications were observed. The IOP was decreased slightly after 1 month(t = 6.238, P < 0.05), but no changes after 3 months (t = 0.053, P < 0.05). The SMILE procedure is good at the safety, efficacy, predictability and stability for the correction of myopia and myopic astigmatism.
    [Zhonghua yan ke za zhi] Chinese journal of ophthalmology 04/2013; 49(4):292-8.
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    ABSTRACT: The aim of the present study is to re-evaluate the original cohort of patients who participated in the first photorefractive keratectomy (PRK) trial in the 1990s, especially their optical performance. Forty-four eyes (24 patients) of the original cohort who underwent PRK using the NIDK EC-5000 excimer laser platform returned 10 years (range 9-14 years) postoperatively to have higher-order aberrations (HOAs) recorded. Wavefront aberrations were measured using Wavescan (VISX, Santa Clara, CA, USA) and calculated for 3- and 6-mm pupil size. The total RMS (the square root of the sum of squared Zernike coefficients) of higher-order wavefront error (3rd-6th radial order) and the Zernike coefficients, as well as the third-order (S 3) and fourth-order (S 4) aberrations, spherical aberrations and coma aberration values were analyzed. An independent sample t test was used for comparisons and a P value <0.05 was considered statistically significant. The mean RMS of higher-order wavefront values showed an increase but no significant difference in postoperative eyes compared to the control-matched normal level with the 6-mm pupil (HOA RMS: control group 0.31 ± 0.12 μm; 10-year post-PRK group 0.56 ± 0.15 μm; P = 0.141). The main contribution was the increase of spherical aberrations (Z 12) and spherical-like aberrations (S 4), which increased by fourfold and 2.5-fold, respectively, in the 10-year post-PRK group (control group Z 12 0.08 ± 0.11 μm, S 4 0.14 ± 0.05 μm; 10-year post-PRK group Z 12 0.35 ± 0.15 μm, S 4 0.37 ± 0.14 μm; P = 0.010*). Most increases of ocular HOAs induced by corneal refractive surgery are becoming extremely minor at 10 years postoperatively, closer to the corresponding preoperative amount. The largest increase was spherical and spherical-like aberrations, especially with a larger pupil size.
    International Ophthalmology 03/2013; 33(6). DOI:10.1007/s10792-013-9759-x · 0.55 Impact Factor
  • Yongji Liu · Yan Wang · Zhaoqi Wang · Tong Zuo
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    ABSTRACT: To investigate the sources of error in corneal power measurement before and after corneal refractive surgery for myopia. The study comprised 28 eyes of six males and eight females with a mean age of 26 (range 18-39 years). The radius of curvature of anterior and posterior corneal surface, Q-Values of anterior and posterior corneal surface and corneal central thickness were measured by rotating Scheimpflug imaging (Pentacam). The true net power F(g), back vertex power F(v), and keratometric power SimK, were calculated respectively at the apex and at a paracentral area on the 3 mm ring. For virgin eyes, the overestimation (0.53 ± 0.11 D) of the corneal power by using a keratometric index of 1.3375 was balanced by the underestimation (-0.21 ± 0.09 D) of the corneal power by the error in the radius of curvature, resulting in a relatively small corneal power error with a mean value of 0.33 ± 0.11 D. With the Q-value changing from -0.09 to -0.41, the percentage balanced by the error in radius of curvature increased from 16% to 73%. However, for eyes after laser refractive surgery, the radius of curvature error lead to an overestimation (0.54 ± 0.16 D) of the corneal power and the keratometric index of 1.3375 again overestimated (1.59 ± 0.26 D) the corneal power, resulting in a large measurement error with a mean value of 2.12 ± 0.40 D. With the Q-value changing from 0.35 to 1.89, the percentage added by the error in radius of curvature increased from 14% to 32%. For virgin eyes, the overestimation of the corneal power by using a keratometric index of 1.3375 is balanced by the underestimation of the corneal power by the error in the radius of curvature, resulting in a relatively small corneal power error. However, for eyes after laser refractive surgery, the flatter anterior corneal surface means that the use of a keratometric index of 1.3375 significantly overestimates the corneal power and the radius of curvature error now adds to this overestimation and results in a large measurement error.
    Ophthalmic and Physiological Optics 07/2012; 32(4):355-61. DOI:10.1111/j.1475-1313.2012.00921.x · 2.66 Impact Factor
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    ABSTRACT: To investigate the changes and relevant factors of forward scatter after Epipolis laser in situ keratomileusis (Epi-LASIK)and laser in situ keratomileusis (LASIK). It was a prospective clinical comparative study. 45 patients (45 eyes) were scheduled for Epi-LASIK and 42 patients (42 eyes) for LASIK. Straylight examinations were performed using the C-Quant straylight meter before and 1, 4, 10 months after surgery. The data was analyzed for statistical significance by one-way ANOVA and the correlation was tested by Pearson's test by using SPSS 13.0 software. The straylight values were (0.91 ± 0.17), (1.03 ± 0.15), (1.11 ± 0.13), (1.01 ± 0.16) of Epi-LASIK group and (0.96 ± 0.14), (1.05 ± 0.12), (1.10 ± 0.12), (0.98 ± 0.15) of LASIK group preoperatively and 1, 4, 10 months postoperatively respectively, which there were significant increase postoperatively in both groups (F = 12.29, 8.11; P < 0.05). Compared with preoperative values, the changes in straylight values at 1, 4 and 10 months postoperatively were (0.12 ± 0.18), (0.19 ± 0.20), (0.08 ± 0.16) of Epi-LASIK group and (0.09 ± 0.13), (0.15 ± 0.17), (-0.01 ± 0.17) of LASIK group. In Epi-LASIK group, the preoperative refractive error, RBT/CCT, and ablation ratio have significant relevance with straylight values at 4 months postoperatively (r = -0.344, -0.361, 0.361; P < 0.05), no such correlation was found in LASIK group (r = 0.186, 0.162, -0.206; P > 0.05). For corneal haze which was found from 1 to 4 months after Epi-LASIK, grade 2, 1, 0.5 appeared in 1, 2, 4 eyes respectively and the changes of straylight values were 0.52, (0.37, 0.42), (0.06, 0.09, 0.07, 0.17) at 4 months postoperatively. 10 months postoperatively, the increases of straylight values for the eye with grade 2 haze declined from 0.52 to 0.11 after the haze disappeared. Straylight values increase significantly at early time after Epi-LASIK and LASIK, but decrease partially as time going. Corneal wound healing response may be the reasons induced the increases of light scatter after Epi-LASIK. For LASIK, flap interface factors may be the reasons. Corneal haze especially above mild grade, can affect the straylight obviously.
    [Zhonghua yan ke za zhi] Chinese journal of ophthalmology 07/2011; 47(7):589-95. DOI:10.3760/cma.j.issn.0412-4081.2011.07.004
  • Mei Zhang · Zhao-Qi Wang · Yan Wang · Tong Zuo
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    ABSTRACT: A chromatic corrector with two refractive–diffractive hybrid elements is designed over a reasonable wide field-of-view of 7° to correct the chromatic aberrations of human eye. We investigate the performance of the corrector using several optical criteria in a comparison with the chromatic corrector with single refractive–diffractive element. Both the correctors can correct the longitudinal chromatic aberration (LCA) fairly. It is demonstrated that the chromatic corrector with single element introduces serious eccentric transverse chromatic aberration (TCA), which deteriorates the image quality at the edge field-of-view. On using the chromatic corrector with two refractive–diffractive elements, not only the LCA but also the TCA can be corrected very well. The designed chromatic corrector can be used to improve the retinal image quality and has potential application in the design of visual instruments.
    Optik - International Journal for Light and Electron Optics 12/2010; 121(24-121):2209-2212. DOI:10.1016/j.ijleo.2009.09.004 · 0.77 Impact Factor
  • Mei Zhang · Zhao-Qi Wang · Yan Wang · Tong Zuo
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    ABSTRACT: Two kinds of individual eye models, with and without involving the angle between visual axis and optical axis, are constructed according to the measurements of the corneal surfaces, the optical axis lengths and wavefront aberrations. The constructed eye models are then used to investigate the properties of the transverse chromatic aberration (TCA) and its influence on visual performance. The statistical distributions of the horizontal TCA, vertical TCA and the absolute magnitude of the TCA over the spectrum from 470 to 650 nm are provided, respectively. The variations of TCA with wavelength as referring to the central wavelength of 555 nm for five subjects are also provided. Then we evaluate the impact of TCA on image performance in comparison with longitudinal chromatic aberration (LCA). It is shown that LCA is more detrimental than foveal TCA in image quality. It is found that, while LCA was corrected well, the foveal TCA is simultaneously corrected. Finally, we investigate the correction of peripheral TCA with an achromatizing element. The correction of peripheral TCA of human eye strongly depends on the location of the achromatizing element, and with the element in front of the eye, the peripheral TCA cannot be corrected.
    Optik - International Journal for Light and Electron Optics 11/2010; 121(22):2080-2086. DOI:10.1016/j.ijleo.2009.07.009 · 0.77 Impact Factor
  • Bo-Yan Li · Zhao-Qi Wang · Yan Wang · Tong Zuo
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    ABSTRACT: Previous Monte Carlo simulations which manipulate each Zernike coefficient of total aberrations of human eyes indicate that interactions among wave-front aberrations can provide better visual quality for both pre-LASIK eyes and post-LASIK eyes. In this paper, we go a step further for Monte Carlo simulations which are not only on total aberrations but also on corneal aberrations, before and after LASIK, for a set of eyes. The corneal aberrations after LASIK are acquired through a new reliable method. Then a series of Monte Carlo simulations (including sign simulation, value simulation and meridional simulation) are performed by manipulating each Zernike coefficient (second through sixth-order) of total aberrations as well as corneal aberrations. The results are evaluated by modulation transfer function (MTF) ratio. Total aberrations for post-LASIK eyes still show MTF advantage over randomized aberrations, with slightly change as compared to that for pre-LASIK eyes. However, true corneal aberrations before and after LASIK have no MTF advantage over random aberrations. From this research, we draw conclusions: there is apparent advantage for the complete eye's true aberrations over random aberrations, whether pre-LASIK or post-LASIK, which does not exist for any biological optical surfaces in isolation, and the ability of adaptive mechanism of human eyes, increases after LASIK.
    Optik - International Journal for Light and Electron Optics 06/2010; 121(10):908-913. DOI:10.1016/j.ijleo.2008.09.047 · 0.77 Impact Factor
  • Mei Zhang · Zhao-Qi Wang · Yan Wang · Tong Zuo
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    ABSTRACT: The aim of this research is to study the properties of the transverse chromatic aberration (TCA) after the LASIK refractive surgery based on the individual eye model involving the angle between visual axis and optical axis. According to the measurements of the corneal surfaces, the optical axis lengths and the wavefront aberrations, the individual eye models before and after LASIK refractive surgery are constructed for 15 eyes by using ZEMAX optic design software, while the angle between the visual axis and optical axis is calculated from the data of the anterior corneal surface. The constructed eye models are then used to investigate the variation of the TCA after the surgery. The statistical distributions of the magnitude of the foveal TCA for 15 eyes over the visible spectrum are provided. Finally, we investigate the influence of the TCA on the visual quality and compare the results with previous research. The TCA is an indispensable criterion to evaluate the performance of the refractive surgery. This research is very meaningful for the studies of not only foveal vision but also the peripheral vision.
    Proceedings of SPIE - The International Society for Optical Engineering 05/2010; DOI:10.1117/12.867936 · 0.20 Impact Factor
  • Ming Liu · Zhao-Qi Wang · Yan Wang · Tong Zuo · Yang Wang
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    ABSTRACT: Theoretical calculations of the wavelength dependence of the ocular wavefront aberrations are performed with individual eye model. Individual eye model, based on the traditional Gullstrand–Le Grand eye model, has been established with measured individual cornea data, eyeball depth and wavefront aberrations. We analyze the wavelength-dependent wavefront aberrations at 12 different visible wavelengths (between 400 and 750nm) for eight eyes. The change of defocus with wavelength (longitudinal chromatic aberration, LCA) is noticeable, and in good agreement with the results from references. In most cases, the primary spherical aberration changes significantly with wavelength. In comparison with the primary spherical aberration, the other higher-order wavefront aberrations have a smaller change with wavelength. These results have potential applications in those situations where defocus or higher-order wavefront aberrations information in arbitrary wavelength is required.
    Optik - International Journal for Light and Electron Optics 06/2008; 119(8):383-387. DOI:10.1016/j.ijleo.2007.01.002 · 0.77 Impact Factor
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    ABSTRACT: In this research, we firstly construct individual eye models based on the wavefront and the measured cornea structure of the eyes. Then we analyze the influence of accommodation on the wavefront aberrations based on individual eye model. The individual eye model has the same wavefront aberration as that measured from Hartmann–Shack wavefront sensor. The optical design software ZEMAX is used to construct the individual eye models for 20 normal eyes. Accommodative conditions are from 0 to –4 diopter in steps of one diopter. The variations of the total, the spherical, the coma and the higher-order root-mean-square wavefront aberrations, as accommodations, are illustrated. Influence of accommodation on wavefront aberration varies from individual to individual, and the variation magnitude is independent of the magnitude of the wavefront aberration of the eye.
    Optik - International Journal for Light and Electron Optics 06/2007; DOI:10.1016/j.ijleo.2006.03.019 · 0.77 Impact Factor
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    ABSTRACT: The recent studies have shown that visual performance might be affected by the ocular aberration after the corneal refractive surgery, and try to minimize it. This study was to investigate the effects of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) on the higher order of wavefront aberration and analysis of their characteristics. This prospective study involved 32 eyes with similar refractive powers (-5.0 D to -6.0 D preoperatively). LASIK and PRK were performed with the same parameters of 6 mm diameter optical zone and 7 mm diameter transition zone ablation. Wavefront aberrations were tested using a ray tracing technique preoperatively and 3 months postoperatively. Three measurements were obtained for each condition; the root mean squared wavefront error (RMS), values for overall wavefront aberrations and each order of the Zernike aberrations were analyzed using the Matlab software. The 2-tailed t test was used for statistical analysis. Overall higher order aberrations were increased from (0.550.26) microm preoperatively to (0.930.37) microm for PRK and (0.790.38) microm for LASIK postoperatively. This was a 1.69 fold increase in the PRK group (t = 3.95, P < 0.001) and a 1.43 fold increase in the LASIK group (t = 2.60, P < 0.05). At 3 months, the mean RMS value for higher-order (3rd to 6th) were significantly increased compared with the corresponding preoperative values (P < 0.05). The fourth order aberrations, spherical like aberration, were dominant by a 2.64 fold in PRK and a 2.31 fold in LASIK. Different influences of the PRK group and LASIK group were shown in the various zernike components. The statistically significant differences were seen in C(4)(0), C(4)(+4), C(5)(+1), C(5)(+3), C(5)(+5) and C(6)(+2) of the PRK group and C(3)(-3), C(4)(0), C(5)(-5), C(5)(+5), C(6)(-2) of the LASIK group, which represents a 7.42, 3.58, 9.21, 2.72 and 5.3 fold increases in PRK group, and 6.40, 10.80, 11.06, 3.47 and 6.09 fold increases in LASIK group, respectively. C(3)(-3) in LASIK was higher and C(5)(+1) and C(5)(+3) were lower than those in the PRK group. C(4)(0) (spherical aberration) values were similar between PRK and LASIK, however, C(3)(-1) and C(3)(1) (coma) in LASIK were higher than those in PRK, but these differences are of no statistical significance. PRK and LASIK may increase ocular higher-order aberrations, but they both have their own features. The difference between the two types of surgery may be correlated with the change of the corneal shape, the conversion of biodynamics, the healing of the corneal cut, and re-structured corneal epithelium and/or the stroma.
    Chinese medical journal 03/2007; 120(4):269-73. · 1.02 Impact Factor
  • Yang Wang · Zhaoqi Wang · Yan Wang · Tong Zuo
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    ABSTRACT: In this research, we firstly design the phakic intraocular lens (PIOL) based on individual eye model with optical design software ZEMAX. The individual PIOL is designed to correct the defocus and astigmatism, and then we compare the PIOL power calculated from the individual eye model with that from the experiential formula. Close values of PIOL power are obtained between the individual eye model and the formula, but the suggested method has more accuracy with more functions. The impact of PIOL decentration on human eye is evaluated, including rotation decentration, flat axis decentration, steep axis decentration and axial movement of PIOL, which is impossible with traditional method. To control the PIOL decentration errors, we give the limit values of PIOL decentration for the specific eye in this study.
    Optik - International Journal for Light and Electron Optics 02/2007; 118(2):88-93. DOI:10.1016/j.ijleo.2006.02.003 · 0.77 Impact Factor
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    ABSTRACT: To investigate the relationship between mild and moderate corneal haze and the distribution of higher order wavefront aberrations after photorefractive keratectomy (PRK). Thirty-six eyes from 18 patients who underwent PRK were divided into two groups: 10 eyes with corneal haze and 26 eyes without corneal haze (control). All eyes were evaluated up to 6 months after PRK. Wavefront aberrations were measured using a psychophysical wavefront sensor and the NIDEK OPD-Scan. Topography, point spread function, and modulation transfer function maps were obtained from the OPD-Scan. The mean total higher order aberration was slightly higher in the corneal haze group than in the control group. This difference was not statistically significant. The mean third order coma aberrations were higher and mean fourth order spherical aberrations were lower in the haze group compared with the control group, although neither difference attained statistical significance. The t test values were 1.05, -0.38, -1.10, -0.08, and -0.23, when comparing the mean third, fourth, fifth, sixth, and seventh order aberrations, respectively. None of these differences attained statistical significance. In terms of Zernike coefficients, Z-1 and Z1 showed greater mean root-mean-square (RMS) in the haze group (0.33 and 0.35 microm, respectively) than those for the control group (0.26 and 0.23 microm, respectively) (t=0.71 and P=.49; t=0.84 and P=.43, respectively). However, ZO had lower RMS in the haze group (0.18 microm) than in the control group (0.28 microm). This difference also was not statistically significant. In this study comparing the optical aberrations of eyes with and without corneal haze after PRK, corneal haze did not affect the magnitude and distribution of higher order aberrations in a predictable manner.
    Journal of refractive surgery (Thorofare, N.J.: 1995) 12/2006; 22(9 Suppl):S1031-6. · 3.47 Impact Factor
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    Wei Wang · Zhao-Qi Wang · Yan Wang · Tong Zuo
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    ABSTRACT: The wave-front aberrations of the anterior corneal surface, the posterior corneal surface and the complete eye have been measured by a corneal topographic system (Orbscan II) and a Hartmann–Shack wave-front sensor. We have calculated the aberrations for both the corneal surfaces with the discrete set of corneal elevation data, and with which to acquire the aberrations of the whole cornea. The aberrations of the crystalline lens are calculated by subtracting the aberrations of the cornea from that of the complete eye. The aberration combination between the anterior and the posterior corneal surface, between the cornea and the crystalline lens is complicated, either compensation or addition. For individual Zernike terms, astigmatism and quatrefoil in the anterior corneal surface are added by the posterior corneal surface, while some other terms show compensation between the two surfaces. And for complete eye, astigmatism and spherical aberrations in the cornea are partially compensated by the crystalline lens, and other terms show addition between the two parts. Individual eye shows different combinations of compensation and addition across different Zernike terms.
    Optik - International Journal for Light and Electron Optics 09/2006; 117(9-117):399-404. DOI:10.1016/j.ijleo.2005.10.009 · 0.77 Impact Factor
  • Wei Wang · Zhaoqi Wang · Yan Wang · Tong Zuo
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    ABSTRACT: In order to understand the relative contribution of the wave-front aberrations of the cornea and the crystalline lens to the retinal image quality in the human eye, we have measured the wave-front aberrations of the anterior corneal surface, the posterior corneal surface and the complete eye with a corneal topographic system (Orbscan) and a Hartmann-Shack wave-front sensor. The 20 subjects selected to participate in the study are all no eye diseases, covering a range of age from 18 to 25. All the subjects have refractive errors of defocus varying from 0.5 D to 5 D and astigmatism varying from 0.1 D to 1.5D. Using the Orbscan, we obtained the discrete set of corneal elevation data in radial distribution over the pupil plane for the anterior and the posterior corneal surfaces directly, and the data are then transformed into wave-front aberrations of both the corneal surfaces. The wave-front aberrations of the two surfaces are then used to acquire the aberrations in whole cornea. The aberration contribution of the crystalline lens is obtained by subtracting the aberrations in the cornea from that in the complete eye. It is shown that the combination of the aberrations between the crystalline lens and the cornea could be either a compensatory or an additive process. The effect of the combination between the anterior and the posterior corneal surface is also complicated, and the aberration compensation, as well as aberration addition can be observed. It is shown from statistics point of view that the anterior corneal surface contributes more lower-order aberrations (astigmatism) to the complete eye, while the posterior corneal surface and the crystalline lens play a more important role in contributing higher-order aberrations.
    Proceedings of SPIE - The International Society for Optical Engineering 12/2005; DOI:10.1117/12.669276 · 0.20 Impact Factor
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    Yan Wang · Kanxing Zhao · Ying Jin · Yafei Niu · Tong Zuo
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    ABSTRACT: To investigate the effect of pupil diameter on higher order aberration in myopic eyes. One hundred and two eyes of 51 normal subjects were evaluated with the Nidek OPD-Scan. All types of aberration increased significantly with increasing pupil size (P<.001). However, optical aberrations had a less pronounced increase in C3(-1) and C3(+1) , more pronounced increase in C4(0) with pupil area increased (P<.05), 2nd coma (C5(-1) and C6(+1)) and high order astigmatism (C4(-2), C4(+2) C6(-2), C6(+2) with larger pupil diameter. Compared with the aberrations of each high order aberration at 4 mm, the average increase root mean square values were 1.54, 1.59, 1.71, and 1.87 on S3, S4, S5, and S6 respectively, with a 5-mm pupil, whereas increased root mean square values were 1.46, 1.88, 1.51, and 1.60 for a 6-mm-diameter pupil. For an equal increase of pupil size, not all Zernike polynomial coefficients induced equivalent increase of values. Coma-like aberrations increased less with pupil dilation. Spherical-like aberration showed only a small increase from 4 mm to 5 mm pupil size, but a larger increase from 5 mm to 6 mm pupil size. Other higher order aberrations (S5 and S6) increased slightly with pupil dilation. Coma-like aberration was larger than spherical aberration, and larger than other higher order aberrations for all pupil sizes.
    Journal of refractive surgery (Thorofare, N.J.: 1995) 11/2002; 19(2 Suppl):S270-4. · 3.47 Impact Factor

Publication Stats

104 Citations
20.42 Total Impact Points

Institutions

  • 2006–2014
    • Tianjin Eye Hospital
      T’ien-ching-shih, Tianjin Shi, China
  • 2002–2013
    • Tianjin Medical University
      T’ien-ching-shih, Tianjin Shi, China
  • 2005
    • Nankai University
      • Institute of Modern Optics (IMO)
      T’ien-ching-shih, Tianjin Shi, China