Study of wavefront aberrations on the corneal anterior surface and related factors in patients after corneal refractive surgery

2019 ◽  
Author(s):  
Cheng-Zhe Wu ◽  
Xun Cui ◽  
Zheng-Ri Li ◽  
Hong Cui ◽  
Hua Jin ◽  
...  
Keyword(s):  
Refractive Surgery ◽  
Spherical Aberration ◽  
Anterior Segment ◽  
Higher Order ◽  
Spherical Equivalent ◽  
Wave Surface ◽  
Related Factors ◽  
Wavefront Aberrations ◽  
Corneal Refractive Surgery ◽  
Analysis System

Abstract Background To investigate the characteristics and distribution of anterior and posterior surface wavefront aberrations in patients suitable for corneal refractive surgery. Methods Sixty myopic patients (120 eyes, 14-46 years old) who underwent corneal refractive surgery were randomly selected by the Pentacam anterior segment analysis system with a spherical equivalent (SE) of -1.50 to -12.00 D. The corneal anterior and posterior aberrations (higher-order aberration, HOA; spherical aberration, SA; Coma; Trefoil) and Q and K values were detected, and a correlation analysis of the relevant parameters was carried out. Results The root mean square (RMS) values from 3 to 6 (RMS 3 to 6) of the whole eye higher-order wave surface aberrations at a 6.0 mm pupil diameter showed a decreasing trend in patients with corneal refractive surgery, and an RMS value of 3 accounted for 62.92% of the total HOAs. The coma ratio increased with increasing diopter, while the spherical aberration ratio was not changed. In addition, the spherical aberration was 0.203 ± 0.082 μm (range: 0.061 to 0.503 μm), and the Q30 was -0.19 ± 0.03 (range: -0.58 to 0.31), which showed a normal distribution. There were significant differences in coma aberrations (3, 1) in the low, middle and high myopia groups (P=0.013). The spherical equivalent was positively correlated with corneal coma (R = -0.241, P = 0.009), and the Q value was positively correlated with total higher-order as well as spherical aberrations (R = 0.326, P <0.001; R = 0.675, P <0.001). Conclusions Individual wavefront aberrations on the anterior and posterior surfaces of the cornea are comparatively different, and the Zernike coefficients are related to the degree of myopia. Spherical aberrations are the most overriding aberrations of the cornea.

scholarly journals Study on the corneal higher-order aberrations and correlation in patients with different degrees of myopia suitable for wavefront-guided FS-LASIK

2019 ◽  
Author(s):  
Cheng-Zhe Wu ◽  
Xun Cui ◽  
Zheng-Ri Li ◽  
Hong Cui ◽  
Hua Jin ◽  
...  
Keyword(s):  
Refractive Surgery ◽  
Spherical Aberration ◽  
Anterior Segment ◽  
Higher Order ◽  
Spherical Equivalent ◽  
Higher Order Aberrations ◽  
Wavefront Aberrations ◽  
The Third ◽  
Corneal Refractive Surgery ◽  
Analysis System

Abstract Background: To investigate the characteristics and distribution of anterior and posterior surface wavefront aberrations in patients suitable for corneal refractive surgery. Methods: A total of 121 myopic patients (121 eyes, 14-46 years old) who underwent corneal refractive surgery were randomly selected by the Pentacam anterior segment analysis system with a spherical equivalent (SE) of -1.50 to -12.00 D. The corneal anterior and posterior aberrations (higher-order aberration, HOA; spherical aberration, SA; Coma; Trefoil) and Q and K values were detected, and a correlation analysis of the relevant parameters was carried out. Results: The root-mean-square (RMS) of the third to sixth order aberrations of the ocular and corneal wave surface aberrations at a 6.0-mm pupil showed a decreasing trend in patients suitable for the corneal refractive surgery, and the RMS of the third order aberrations accounted for 62.92% of the total HOAs. The coma ratio (coma ratio: coma/total cornea higher-order aberrations) was increased with the increasing diopters, while the spherical aberration ratio (spherical aberration/ total cornea higher-order aberrations) was not changed. In addition, the spherical aberration was 0.203± 0.082 μm (range: 0.061 to 0.503 μm), and the Q30 was -0.19±0.03 (range: -0.58 to 0.31). There were significant differences in the coma aberrations of preoperative corneal anterior surface (3, 1) between the low, middle and high myopia groups (P=0.013). The spherical equivalent was positively correlated with the corneal coma of the preoperative anterior corneal surfaces (R=-0.241, P=0.009), and the Q value was positively correlated with the total higher-order aberrations (R=0.326, P<0.001). Conclusions: Individual wavefront aberrations on the anterior and posterior surfaces of the cornea are comparatively different, and the Zernike coefficients are related to the degree of myopia. Spherical aberrations are the most overriding aberrations of the cornea.

scholarly journals Study on the corneal higher-order aberrations and correlation in patients with different degrees of myopia suitable for wavefront-guided FS-LASIK

2019 ◽  
Author(s):  
Cheng-Zhe Wu ◽  
Xun Cui ◽  
Zheng-Ri Li ◽  
Hong Cui ◽  
Hua Jin ◽  
...  
Keyword(s):  
Refractive Surgery ◽  
Spherical Aberration ◽  
Anterior Segment ◽  
Higher Order ◽  
Spherical Equivalent ◽  
Anterior Surface ◽  
Higher Order Aberrations ◽  
Wavefront Aberrations ◽  
The Third ◽  
Corneal Refractive Surgery

Abstract Background: To investigate the characteristics and distribution of anterior surface wavefront aberrations in patients suitable for corneal refractive surgery. Methods: A total of 121 myopic patients (121 eyes, 18-45 years old) who underwent corneal refractive surgery were randomly selected by the Pentacam anterior segment analysis system with a spherical equivalent (SE) of -0.25 to -10.00 D. The corneal anterior aberrations (total higher-order aberration; spherical aberration; Coma; Trefoil) and Q and K values were detected, and a correlation analysis of the relevant parameters was carried out. Results: The root-mean-square (RMS) of the third to sixth order aberrations of the corneal anterior wavefront aberrations at a 6mm analysis diameter showed a decreasing trend in patients suitable for the corneal refractive surgery, and the RMS of the third order aberrations accounted for 62.92% of the total HOAs. The coma ratio (coma/total cornea higher-order aberrations) was increased with the increasing diopters, while the spherical aberration ratio (spherical aberration/ total cornea higher-order aberrations) was not changed. In addition, the spherical aberration was 0.203±0.082 μm (range: 0.061 to 0.503 μm), and the Q30 was -0.19±0.03 (range: -0.58 to 0.31). There were significant differences in the coma aberrations of preoperative corneal anterior surface (3, 1) between the low, middle and high myopia groups (P=0.013). The spherical equivalent was positively correlated with the corneal coma of the anterior corneal surfaces (R=-0.241, P=0.009), and the Q value was positively correlated with the total higher-order aberrations (R=0.326, P<0.001). Conclusions: Individual wavefront aberrations on the anterior surfaces of the cornea are comparatively different, and the Zernike coefficients are related to the degree of myopia. Spherical aberrations are the most overriding aberrations of the cornea.

scholarly journals Misalignment and tilt effect on aspheric intraocular lens designs after a corneal refractive surgery

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243740
Author(s):  
Jesús Pérez-Gracia ◽  
Francisco J. Ávila ◽  
Jorge Ares ◽  
Juan A. Vallés ◽  
Laura Remón
Keyword(s):  
Image Quality ◽  
Refractive Surgery ◽  
Spherical Aberration ◽  
Optical Quality ◽  
Intraocular Lenses ◽  
Modulation Transfer ◽  
Wavefront Aberrations ◽  
Corneal Asphericity ◽  
Corneal Refractive Surgery ◽  
Image Position

Purpose To numerically evaluate and compare the tolerance to misalignment and tilt of aspheric intraocular lenses (IOLs) designed for three eyes: with standard cornea and with simulated corneas after myopic and hyperopic laser ablation surgery. Methods Three aspheric IOLs of +20.00 diopter (D) with different spherical aberration (SA) (Z40) values have been designed using a theoretical model eye. Drastic changes on the theoretical eye anterior corneal asphericity have been performed to simulate myopic and hyperopic refractive surgeries. The effect of IOL misalignment and tilt on the image quality has been evaluated using a commercial optical software design for the three eye models. Image quality was assessed from the modulation transfer function (MTF), root mean square (RMS) values of defocus, astigmatism, coma and spherical aberration (Z40), and retinal images obtained from a visual simulator using an aleatory optotype of 0.00 LogMar visual acuity (VA). Results IOL misalignment and tilt reduced MTF values in general, and increased wavefront aberrations errors. Aberration-free IOLs maintained best the MTF values when misalignments were applied, together with good on-axis optical quality. IOLs with negative SA (Z40) correction decreased the MTF value under 0.43 for misalignments values higher than 0.50 mm with the three corneas. The effect of misalignment on RMS astigmatism and coma was correlated with the IOL SA (Z40) and with the three corneas. Conclusions This theoretical study shows that the largest degradation in image quality arises for the IOL with the highest amount of spherical aberration (Z40). Moreover, it has been found that the aspherical design has a more influential role in misalignment tolerance than in tilt tolerance.

scholarly journals Correlation between Central Corneal Thickness and Degree of Myopia among Malaysian Patients Undergoing Laser Keratorefractive Surgery

2020 ◽  
pp. 52-58
Author(s):  
Sagili Chandrasekhara Reddy ◽  
Mohd Mansor Shariff ◽  
Aina Malindri Dasrilsyah
Keyword(s):  
Optical Coherence Tomography ◽  
Refractive Surgery ◽  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Anterior Segment ◽  
Military Hospital ◽  
Moderate Degree ◽  
Optical Coherence ◽  
Corneal Refractive Surgery ◽  
The Mean

Purpose: To determine the central corneal thickness in myopic adult patients scheduled for laser corneal refractive surgery and to explore its correlation with degree of refractive error. Materials and Methods: The case records of 130 myopic patients who underwent laser corneal refractive surgery in a military hospital over a period of two years were reviewed to determine the central corneal thickness. All patients had 6/6 vision with best correction, and did not have any other anterior segment or fundus diseases in both eyes. The central corneal thickness was measured with Visante Carl Zeiss anterior segment optical coherence tomography instrument.                                                                                                                        Results: Out of 130 patients, males were more (73, 56.2%); mean age of patients was 33.8 years (range 18-60 years) and majority were Malays (110, 84.6%).  The spherical power of myopia ranged from – 0.5 to – 10.00 D, and the cylindrical power ranged from – 0.25 to – 3.25 D. The mean central corneal thickness of both eyes was 528.2 µm (range 331- 615 µm); in the mild degree of myopia (- 0.50 to - 2.00 D) 527.9 µm, moderate degree (- 2.25 to -5.00 D) 529.4 µm, and high degree (-5.25 to -11.00 D) 523.9 µm. Conclusion: The anterior segment optical coherence tomography provides noncontact, rapid, pachymetry mapping of the corneal thickness. In Malaysian patients, the mean central corneal thickness of both eyes in myopia was 528.1 µm (range 331- 615 µm). There was no correlation between the mean central corneal thickness and degree of myopia, different genders, age groups, ethnic groups and two eyes.

scholarly journals Ablation Resolution in Laser Corneal Refractive Surgery: The Dual Fluence Concept of the AMARIS Platform

2010 ◽  
Vol 2010 ◽  
pp. 1-13 ◽  
Author(s):  
Samuel Arba-Mosquera ◽  
Thomas Hollerbach
Keyword(s):  
Flat Plate ◽  
Refractive Surgery ◽  
Spherical Aberration ◽  
Zernike Polynomials ◽  
High Fluence ◽  
Optimal Parameters ◽  
Ablation Time ◽  
Optimum Proportion ◽  
Corneal Refractive Surgery ◽  
Zernike Modes

Purpose. To evaluate to which extent individual Zernike terms can be corrected. Methods. Ablation time and fidelity was analysed using different fluence levels (range 90–2000 mJ/) and aspheric ablation profiles. With optimal parameters, the extent to which individual Zernike modes can be corrected was evaluated. Results. The range 188–565 mJ/ resulted as optimum fluence level with an optimum proportion range 50%–90% for high fluence. With optimal parameters, it corresponds to 2.4 s/D at 6 mm OZ, with fidelity variance of 53 m RMS, and average ablation error of 0.5 m for each location. Ablation simulation of coma Z[3,1] showed 98,4% accuracy and 98% fit quality; trefoil Z[3,3], 99,9% accuracy and 98% fit quality; spherical aberration Z[4,0], 96,6% accuracy and 97% fit quality; secondary astigmatism Z[4,2], 97,9% accuracy and 98% fit quality. Real ablation on a flat plate of PMMA of coma Z[3,1] showed 96,7% accuracy and 96% fit quality; trefoil Z[3,3], 97,1% accuracy and 96% fit quality; spherical aberration Z[4,0], with 93,9% accuracy and 90% fit quality; secondary astigmatism Z[4,2], with 96,0% accuracy and 96% fit quality. Conclusions. Ablation of aspherical and customised shapes based upon Zernike polynomials up to the the 8th order seems accurate using the dual fluence concept implemented at the AMARIS platform.

scholarly journals Ocular higher-order aberrations features analysis after corneal refractive surgery

2007 ◽  
Vol 120 (4) ◽  
pp. 269-273 ◽  
Author(s):  
Yan WANG ◽  
Kan-xing ZHAO ◽  
Ji-chang HE ◽  
Ying JIN ◽  
Tong ZUO
Keyword(s):  
Refractive Surgery ◽  
Higher Order ◽  
Higher Order Aberrations ◽  
Corneal Refractive Surgery

scholarly journals Evaluation of preoperative dry eye in people undergoing corneal refractive surgery to correct myopia

2021 ◽  
Vol 14 (7) ◽  
pp. 1047-1051
Author(s):  
Peng-Fei Zhao ◽  
◽  
Ya-Bin Hu ◽  
Kai Cao ◽  
Ying Qi ◽  
...  
Keyword(s):  
Influencing Factors ◽  
Dry Eye ◽  
Refractive Surgery ◽  
Corneal Thickness ◽  
Tear Film ◽  
Corneal Curvature ◽  
Related Factors ◽  
History Of ◽  
Corneal Refractive Surgery ◽  
Male Patients

AIM: To investigate the incidence of preoperative dry eye and related factors in patients undergoing corneal refractive surgery to correct myopia. METHODS: A total of 141 patients with myopia who underwent corneal refractive surgery were surveyed by questionnaires, tear film break-up time (BUT) test, Schimer I test (SIt), corneal fluorescein staining (FL) test and diagnosed according to the currently recognized domestic diagnostic criteria for dry eye. Correlation analysis of factors such as age, gender, regular wearing of contact lens (CL), diopter (spherical equivalent), corneal thickness, and corneal curvature that may affect the onset of dry eye was carried out to clarify the main influencing factors. RESULTS: There were 64 patients (45.39%) diagnosed with dry eye. The male patients (20.31%) was significantly less than that of non-dry eye subjects (41.56%; χ2=7.260, P=0.007); the proportion of patients with dry eye wearing CL (81.25%) was significantly higher than that of non-dry eye subjects (51.95%; χ2=13.234, P<0.001); the median diopter level of dry eye patients was -6.59 (IQR: -8.87, -4.58) D, and the median diopter level of non-dry eye subjects was -5.69 (IQR: -7.15, -4.03) D. The diopter level of dry eye patients was significantly higher (Z=-2.086, P=0.019). However, the age, best corrected visual acuity, and intraocular pressure of dry eye patients were not statistically different from those of non-dry eye subjects (t=-0.257, -0.383 and 0.778, P=0.798, 0.702, and 0.438); the corneal thickness and corneal curvature (K1 and K2) were also not statistically different either (Z=-1.487, -1.036 and -1.707, P=0.137, 0.300, and 0.088). The research further analyzes the three significant factors in the single factor analysis (gender, CL wear, and diopter) in a multi-factor way: CL wear and diopter were the influencing factors of dry eye disease. Among them, CL wear increased the risk of dry eye by 2.934 times compared with no CL wear; for every 1 D increase in diopter, the risk of dry eye increased by 0.761 times. CONCLUSION: Preoperative dry eye is relatively common in patients who undergo corneal refractive surgery to correct myopia, especially in patients who have a history of CL wear and a high diopter level before surgery. Therefore, it is necessary to carry out preoperative screening and timely treatment of dry eye to obtain the best treatment outcome and postoperative satisfaction.

scholarly journals Anterior Segment Eye Assessment of Refractive Surgery Candidates in the Southeast of Iran

2016 ◽  
Vol 8 (12) ◽  
pp. 133 ◽  
Author(s):  
Neda Nakhjavanpour ◽  
Abolfazl Payandeh ◽  
Majid Rajabi ◽  
Vahid Shoja
Keyword(s):  
Anterior Chamber ◽  
Refractive Surgery ◽  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Weather Conditions ◽  
Capital City ◽  
Linear Regression Models ◽  
Corneal Refractive Surgery

<p>Anterior segment eye parameters are essential factors in diagnosis, screening and management of abnormal ocular conditions. Based on the previous studies, they might differ from one race or population to another. Sistan-and-Baluchestan province, the southeast of Iran, has special weather conditions and race, plus lack of research on these diagnostic factors. Hence, the objective of the present study was to assess anterior segment parameters using pentacam in this area. 800 eyes of subjects which had been referred to the Al-Zahra eye hospital of Zahedan, the capital city of the province, for corneal refractive surgery from October 2014 to March 2015 participated in this research. 95% confidence limits for mean of central corneal thickness, anterior chamber depth and volume were (536.02, 541.20), (3.13, 3.18) and (187.63, 192.58) respectively. Multiple linear regression models showed a lower mean central corneal thickness, and maximum/minimum of keratometry, for males than females, adjusting for age and spherical equivalent. Inversely, anterior chamber depth, and volume were more in males. In order to diagnosis and treating ocular diseases which have effect on retinal thickness, precisely specification of predictive factors is highly needed.</p>

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