Role of spherical aberration and coma in orthokeratology for myopia control / 国际眼科杂志(Guoji Yanke Zazhi)

As a highly prevalent global condition, myopia significantly impacts the ocular health of young individuals in China. Orthokeratology lens, as a rigid corneal contact lens, has demonstrated effective control over the progression of myopia; however, its mechanism of action remains incompletely elucidated. As one of the factors influencing visual acuity, higher-order aberrations will undergo marked changes after orthokeratology, with particular emphasis on the alterations in spherical aberrations and coma. The changes in corneal morphology induced by orthokeratology lead to significant positive increase in both spherical aberration and coma. Furthermore, the elevation of spherical aberration and coma demonstrates a negative correlation with the rate of axial length growth following orthokeratology. The interplay among spherical aberration, coma, defocus, accommodation, astigmatism, and pseudo-accommodation may constitute the underlying mechanism governing the control of myopia through orthokeratology.

Correlations between Quality of Vision, Higher Order Aberrations and Non-Invasive Keratographic Tear Film Break-Up Time in Pseudophakic Eyes after Uncomplicated Phacoemulsification

Aims: In this study, we aimed to investigate the intercorrelations between tear film break up time, measured non-invasively using non-invasive keratographic break-up time (NIKBUT), higher order aberrations (HOA) and quality of vision (QoV) in pseudophakic patients.Study Design: Cross-sectional.Methods: Thirty-five pseudophakic aged patients aged 50 years or older, and 35 control phakic patients aged 17 to 23 years with corrected visual acuity of 20/20 were included in this study. All subjects underwent similar examination including QoV questionnaire, aberrometry to measure HOA, and NIKBUT. HOA was measured with the OPD-Scan/ ARK 10000 corneal analyzer (Nidek CO. Ltd), expressed as Root Mean Square (RMS) HOA and NIKBUT was assessed using non-invasive TF-Scan module Keratograph 5M (K5M), equipped with modified tear film scanning function (Oculus, Wetzlar, Germany). Statistical analysis was performed to find the correlation between NIKBUT, HOA and QoV.Results: Patients in the pseudophakic group were significantly older (median age 66 vs. 20 years; P<0.01), had shorter NIKBUT (10.5 vs. 17.2; P<0.01), lower QoV score (1.63 vs. 0.68; P=0.04), and higher RMS HOA (0.5 vs. 0.26; P<0.01) compared to control group. NIKBUT was inversely correlated with RMS HOA (r = -0.19; p = 0.03) and RMS HOA was significantly correlated with QoV, even after adjustment for age and gender (r = -0.21; P0.04). NIKBUT <9.93s was correlated with lower QoV. The area under the curve was 0.81 (95% CI = 0.67 � 0.95, p = 0.012), and had 100% sensitivity and 61% specificity.Conclusion: Shorter NIKBUT was correlated with greater HOA and greater HOA was correlated with lower QoV. NIKBUT value of shorter than 9.93s could potentially predict pseudophakic patients who will likely experience visual symptoms leading to decreased QoV; thus, the use of artificial tears might be beneficial.

The Effect of Monochromatic Aberrations of the Cornea on Contrast Sensitivity under Photopic and Mesopic Conditions

Purpose: Vision is one of the most important senses. The first stage of vision is the creation of the observed object抯 image on the retina. The quality of the retinal image is affected by several factors, such as diffraction, sampling on the retina, chromatic aberration, scattering and higher order aberrations. The measurement of the quality is achieved both with subjective (visual acuity, contrast sensitivity) and objective methods (PSF, MTF, Strehl ratio, RMS). The purpose of this project is the measurement of higher order aberrations of the anterior corneal surface (with a Placido corneal topographer) and of the contrast sensitivity (with a Pelli Robson optotype). Then, we will try to find if there is a correlation between them.Methods and Materials: 20 persons participated in this survey, divided in two groups of 10 persons each. The first group (group 1) included subjects up to 39 years old and the second group (group 2) from 40 years and up. The participants didn抰 have any pathological problems, except lower order refractive errors. Both eyes of each individual were included in the procedure. First, the higher order aberrations of the anterior corneal surface were measured, with the implementation of a Placido corneal topographer. This was followed by a measurement of the contrast sensitivity. The whole procedure took place under two lighting conditions, both photopic and mesopic. The examination presentation of the higher order aberrations is performed with the use of Zernike polynomials.Results: The results of the measuring procedure showed that for the first group, under photopic conditions (luminance 32.70 cd/m2) the mean value (� standard deviation) for the higher order aberrations RMS and decimal logarithm contrast sensitivity was 0.073 � 0.018?m and 1.54 � 0,16 (contrast 2.88 � 1.24%) respectively. For the second group the corresponding values were 0.080 � 0.036?m and 1.59 � 0.16 (contrast 2.57 � 1.24%). Accordingly, under mesopic conditions (luminance 1.14 cd/m2) the values for the first group were 0.252 � 0.064 ?m and 1.27 � 0.15 (contrast 5.37 � 2.06%), while for the second were 0.253 � 0.069?m and 1.32 � 0.12 (contrast 4.79 � 1.35%). Spherical aberration and coma (horizontal and vertical) were also measured for both groups under photopic and mesopic conditions. The results showed that for the first group, under photopic conditions, RMS for coma and spherical aberration is 0.033 � 0.014 ?m and 0.022 � 0.011 ?m respectively, while for the second group 0.041 � 0.027 ?m and 0.024 � 0.008 ?m. Under mesopic conditions, the relevant results are 0.139 � 0.065 ?m and 0.124 � 0.035?m for the first group and 0.149 � 0.066 ?m and 0.107 � 0.038 ?m for the second group.Finally, we should mention here that the equivalent defocus error corresponding to the higher order aberration RMS was estimated. The results for all the participants (without age separation), are 0.23 � 0.09D (photopic conditions) and 0.28 � 0.07D (mesopic conditions).Conclusions: From the statistical analysis of the results we conclude that there exists a symmetry between left and right eyes regarding higher order aberrations. Furthermore, it seems that age is not a significant factor for differences on the magnitude of higher order aberrations both under photopic and mesopic conditions as well. Similar conclusions are also reached for the contrast sensitivity measurements. In addition, we have observed that a correlation exists between the higher order aberrations of the anterior corneal surface and the contrast sensitivity, for both photopic and mesopic conditions. Correlation also exists between coma and contrast only under photopic conditions. But there is no significant correlation between spherical aberration and contrast. The age difference of these two groups has not an effect on the results. Finally, the equivalent defocus is too small, both for photopic and mesopic conditions and between each other, in order to be clinically significant.

Analysis of postoperative satisfaction, nocturnal visual symptoms and related factors after FS-LASIK / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To analyze satisfaction on night vision and its related factors after FS-LASIK in patients with high and low-to-moderate myopia.<p>METHODS:This was a retrospective study. Totally 75 patients(150 eyes)who underwent FS-LASIK in Xi'an No.1 Hospital from June 2018 to September 2019 were included. All subjects were divided into two groups based on spherical equivalent(SE): high myopia group(SE≥-6.00D)and low-to-moderate myopia group(<-6.00D). Six months after surgery, corneal topography and corneal higher-order aberrations(total HOAs, spherical aberrations, coma and trefoil)under 7mm pupil diameter was investigated by Sirius. Patients were required to complete a questionnaire to evaluate satisfaction and night vision symptoms.<p>RESULTS:For the high myopia group and low-to-moderate myopia group, preoperative SE was -7.85±1.27D and -4.57±1.01D respectively. There were significant differences in total HOAs, spherical aberrations and coma(all <i>P</i><0.001)except for the trefoil(<i>P</i>>0.05)between the two groups. Overall satisfaction was 95.3% and 100.0% in high and low-to-moderate myopia group. 18.8% and 9.3% experienced worsen night vision, 51.2% and 40.6% experienced halo, 41.9% and 43.8% experienced starburst, and 18.6% and 15.6% experienced double vision, respectively. Except that there was significant differences in night vision between the two groups(<i>P</i>=0.010), the occurrence of other night vision symptoms were similar and there were no significant differences in any of them(all <i>P</i>>0.05). For all patients, the satisfaction was correlated with preoperative astigmatism and ablation zone(all<i> P</i><0.05), night vision was correlated with preoperative SE, ablation depth, corneal curvature, total HOAs, spherical aberrations and coma postoperatively(all<i> P</i><0.05), star burst was correlated with preoperative total HOAs, coma and postoperative trefoil(all<i> P</i><0.05), double vision was correlated with preoperative astigmatism(<i>P</i><0.05).<p>CONCLUSION: High myopic patient experienced worsen night vision mainly because of increased total HOAs, spherical aberration and coma. However, symptoms such as halo, starburst and double vision were similar in both groups and did not affect overall satisfaction.

Effects of SMILE and FS-LASIK on early postoperative corneal higher order aberrations in patients with high myopia / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To study the effects of small-incision lenticule extraction(SMILE)and femtosecond laser-assisted excimer laser <i>in situ</i> keratomileusis(FS-LASIK)on early postoperative corneal higher order aberrations(HOAs)and visual quality in patients with high myopia. <p>METHODS:Totally 102 patients(204 eyes)with high myopia who underwent corneal refractive surgery between August 2018 and August 2020 in the hospital were selected as study subjects for the prospective study, and they were randomly divided into SMILE group(51 cases, 102 eyes)and FS-LASIK group(51 cases, 102 eyes). The postoperative visual acuity, corneal HOAs and objective visual quality were compared between the two groups, and the correlation between corneal HOAs and objective visual quality was analyzed. <p>RESULTS: At 1mo after surgery, the spherical equivalent degrees in SMILE group and FS-LASIK group were significantly reduced(<i>P</i><0.05), and there was no statistically significant difference in the proportion of patients with postoperative uncorrected visual acuity≥preoperative best corrected visual acuity between the two groups(95.1% <i>vs</i> 92.2%, <i>P</i>>0.05). The corneal HOAs in the two groups were significantly increased(<i>P</i><0.05), and the overall spherical aberration(SA), trefoil and higher HOAs in SMILE group were lower than those in FS-LASIK group(all <i>P</i><0.05). The objective scattering index(OSI)was significantly increased in the two groups while the MTF cutoff frequency(MTF_cutoff), Strehl Ratio(SR)and contrast visual acuity(VA100%, VA20%, VA9%)were significantly decreased(all <i>P</i><0.05). The OSI of SMILE group was lower than that of FS-LASIK group while MTF_cutoff and VA9% were higher than those of FS-LASIK group(all <i>P</i><0.05). The corneal HOAs in patients with high myopia were negatively correlated with MTF_cutoff and were positively correlated with OSI(<i>P</i><0.05).<p>CONCLUSION:Both SMILE and FS-LASIK can effectively correct high myopia, and SMILE has a smaller increase in early postoperative corneal HOAs, and it is of great significance to relieve visual quality impairment.

Early changes of the corneal higher-order aberrations after femtosecond laser-assisted <i>in situ</i> keratomileusis for different degrees of myopia / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To investigate the early changes of corneal higher-order aberrations(HOAs)of the anterior surface, posterior surface, and total cornea after femtosecond laser-assisted <i>in situ</i> keratomileusis(FS-LASIK)in mild to moderate myopic and high myopic patients. <p>METHODS: This retrospective study included 129 patients(129 eyes)underwent FS-LASIK surgery from December 2018 to December 2019. Treated eyes were divided into two groups, according to the preoperative spherical equivalent(SE): mild to moderate myopic group(<-6.0D, 76 eyes)and high myopic group(≥-6.0D, 53 eyes). Corneal HOAs of the anterior surface, posterior surface, and total cornea were measured by Pentacam anterior segment analysis system preoperatively and 6mo postoperatively. <p>RESULTS: The tHOAs, spherical aberrations and horizontal coma of the anterior surface and total cornea, significantly increased in both groups 6mo postoperatively(all <i>P</i><0.01). And more tHOAs, spherical aberrations and horizontal coma of the anterior surface and total cornea were induced in high myopic group than mild to moderate myopic group postoperatively(all <i>P</i><0.01). The horizontal coma of the posterior surface, significantly increased in both groups 6mo after operation(all <i>P</i><0.01). And more horizontal coma of the posterior surface were induced in high myopic group than mild to moderate myopic group postoperatively(<i>P</i><0.01). Changes in anterior surface and total corneal tHOAs, spherical aberrations and horizontal coma were related to the SE(all <i>P</i><0.01).<p>CONCLUSION:Anterior and total corneal tHOAs, spherical aberrations and horizontal coma, significantly increased after FS-LASIK, and aberration changes were related to SE. Whereas posterior corneal HOAs remained stable except horizontal coma. The long-term effect should be investigated in the future.

Effect of eccentricity of overnight orthokeratology lenses on axial growth and visual quality / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To explore the effect of eccentricity of overnight orthokeratology(OK)lenses on 2-year eye axial growth and visual quality.<p>METHODS:Based on the degree of eccentricity of OK lenses, patients were divided into three groups: a low degree of eccentricity group(degree of eccentricity ≤0.5 mm), a group of moderate eccentricity(eccentric degree >0.5-≤1.0 mm)and a group with a high degree of eccentricity(eccentric degree >1-≤1.5 mm). The degree of eccentricity of the OK lens, spherical equivalent(SE), the uncorrected visual acuity after wearing OK lenses(UCVA), axial length before and after wearing OK lenses(AL), total higher-order aberrations(HOA), comas, and spherical aberrations(SA)for 3 mm pupils were analyzed. The difference among the three groups for all parameters was compared using the Kruskal-Wallis H Rank-Sum test.<p>RESULTS:The study retrospectively analyzed 75 cases(139 eyes). In the low eccentricity group(53 eyes), the mean age was 11.4±2.4 years, SE was -3.24±1.48 D, and AL was 24.85±1.01 mm. In the moderate eccentricity group(53 eyes), the mean age was 11.4±2.2 years, SE was -3.22±1.29 D, and AL was 25.15±0.92 mm. In the high eccentricity group(31 eyes), the mean age was 11.5±1.9 years, SE was -3.54±1.43 D, and AL was 24.95±0.84mm. After two years, there was no significant difference in the changes of the axis among the three groups(<i>P</i>=0.089). The HOA, SA, and coma in the high eccentric group were significantly higher than in the middle eccentric group(<i>P</i><0.05). The HOA, SA, and coma in the high eccentric group were also significantly higher than those in the low eccentric group(<i>P</i><0.05).<p>CONCLUSION:For OK lenses, it is unnecessary to strictly require the absolute centralization of the lens position. An unnecessary change of the lenses may delay the eye-axis control. However, the balance between axial control and visual quality should be assessed.

Comparison of higher order wavefront aberrations with four aberrometers

Purpose: To evaluate the agreement of selected higher order aberration measurements between aberrometers based on three different wavefront technologies. Methods: Twenty-three eyes of 23 participants were compared between Zywave, OPD-Scan III, and iDesign aberrometers, for total ocular aberrations. Participants were between 19 and 69 years of age, and exclusion criteria were previous ocular surgery or trauma, contact lens wear within the preceding 2 weeks, and ocular or systemic disease. Corneal aberrations were compared between the OPD-Scan III and GALILEI™ G2 aberrometers. Zernike coefficients of vertical and oblique trefoil, vertical and horizontal coma, and spherical aberration were analyzed in R software. Results: In all, 276 scans were captured in total, with a male-to-female ratio of 11:12. Total ocular vertical coma [mean difference (MD) = 0.026 ?m, P < 0.005], vertical trefoil (MD = 0.033 ?m, P < 0.05), and spherical aberration (MD = 0.022 ?m, P < 0.05) differed significantly between the iDesign and OPD-Scan III. Differences in total vertical (MD = 0.072 ?m, P < 0.05) and oblique trefoil (MD = 0.058 ?m, P < 0.05) were demonstrated between the Zywave and OPD-Scan III, and spherical aberration (MD = 0.030 ?m, P < 0.005) between iDesign and Zywave. iDesign corneal horizontal coma (MD = 0.025 ?m, P < 0.05) and spherical aberration (MD = 0.043 ?m, P < 0.005) measurements were significantly different between the GALILEI™ G2 and the OPD-Scan III. Conclusion: Zywave, iDesign, and OPD-Scan III, and GALILEITM G2 and OPD-Scan III may be used interchangeably for their total ocular and corneal wavefront functions, respectively; however, care must be taken if using these devices for guiding ablation or monitoring corneal disease.

Study of changes in higher-order aberrations following non-penetrating deep sclerectomy surgery augmented with sub-Tenon injection of MMC in patients with open-angle glaucoma / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To study the changes in higher-order aberrations following non-penetrating deep sclerectomy surgery augmented with sub-Tenon injection of mitomycin C(MMC)in patients with open angle glaucoma<p>METHODS: Twenty eyes from 20 patients were enrolled in the study. There were 10 eyes with primary open angle glaucoma(POAG)and 10 eyes with secondary open angle(SOAG; pseudoexfoliation). Patients underwent non-penetrating deep sclerectomy surgery augmented with sub-Tenon injections(0.2 mL of MMC 0.02%)before surgery. All patients were evaluated in terms of corneal total higher-order aberrations <i>via</i> i-Trace analyzer before surgery and 1mo and 3mo after surgery. The intraocular pressure(IOP), best corrected visual acuity(BCVA), and bleb morphology were evaluated at each visit. The success rate of surgery was categorized as complete, relative, or failure.<p>RESULTS: The IOP before surgery was 24.05±3.07 mmHg with a mean of 2.85±0.67 medication, which reached to 12.30±3.32 mmHg with 0.70±0.98 medication at the 3mo follow-up. The reduction in IOP was significant at all periods of the follow-up(<i>P</i><0.001). The values of total higher-order total(HOT)root mean square(RMS)and total ocular spherical-like aberrations significantly increased at 1mo follow-up after surgery and decreased over the course of 3mo. Trefoil and total ocular coma-like aberration changes were not statistically significant at all periods after surgery. The HOT RMS, coma-like and spherical-like corneal increased significantly 1mo after surgery and decreased at the 3mo follow-up. Corneal trefoil changes were not statistically significant after surgery compared to preoperative state. Patients age and IOP did not have a significant effect on changes in HOT and corneal HOT aberrations.<p>CONCLUSION: Corneal and ocular higher-order aberrations increased within 1mo after deep sclerectomy surgery and then decreased over a 3mo period, which showed no statistically significant change compared to preoperative state. The BCVA and spherical equivalent(SE)of the patients shown no statistically significant differences compared to the preoperative state at the 3mo follow-up.

Comparative analysis of visual outcomes and ocular aberrations following wavefront optimized and topography-guided customized femtosecond laser in situ keratomileusis for myopia and myopic astigmatism: A contralateral eye study

Purpose: To compare the visual outcomes and higher order aberrations (HOAs) following wavefront optimized (WFO) laser in situ keratomileusis (LASIK) versus topography-guided customized ablation (TCAT) LASIK for myopia and myopic astigmatism. Methods: Patients who underwent femtosecond-assisted LASIK for myopic correction between August 2016 and October 2017 were included in this interventional prospective case series. The following parameters were evaluated preoperatively and at 3 months' postoperative visit: uncorrected distance vision acuity (UDVA) and corrected distance vision acuity (CDVA), manifest refraction, and HOAs. Results: Two hundred eyes of 100 patients were included in the study. At 3 months' postoperative visit, 92% and 90% eyes in the TCAT and WFO groups, respectively, demonstrated a UDVA of 20/20 or better (P = 0.90). A residual manifest spherical equivalent within 0.5 D was achieved in 100% and 95% of the eyes in the TCAT and WFO groups, respectively (P = 0.10). No significant difference was observed in the HOAs induced in both the groups, with slightly lower induction of trefoil and horizontal coma in the TCAT group. Conclusion: Both groups demonstrated similar refractive efficacy and predictability, with greater gain of CDVA following TCAT ablation. HOAs induced were not significantly different between the two groups. Further studies are needed to validate the superiority of one procedure over the other.

Comparative study of clinical efficacy after LASIK with corneal flap created by femtosecond laser and microkeratome / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To observe the clinical efficacy after LASIK with corneal flap created by femtosecond laser and microkeratome.METHODS:The ophthalmic myopia patients after LASIK with corneal flap created by femtosecond laser or microkeratome in our hospital,50 cases (100 eyes) each,were inspected for uncorrected vision,residual diopter,dry eyes survey,higher order aberrations at 1,3 and 6mo after surgeries.RESULTS:There were no statistical differences between two groups of uncorrected vision and residual diopter in 6mo after surgery (P＞ 0.05).The incidence of dry eye comparison for postoperative 1 and 3mo were significantly different (P ＜ 0.05),but there were no statistical differences for postoperative 6mo (P＞0.05).The higher order aberrations of the two groups increased after surgery,the differences were significant compared with preoperative(P＜0.05).At 1mo after surgeries,horizontal coma aberration,vertical coma aberration and spherical aberration were not significantly different (P＞0.05).At 3 and 6mo after surgeries,horizontal coma aberration and vertical coma aberration were not significantly different (P＞0.05).And the change of spherical aberration after LASIK with corneal flap created by femtosecond laser was less than that with microkeratome (P＜0.05).CONCLUSION:LASIK with corneal flap created by femtosecond laser is a safe,effective and stable surgical approach.The incidence of dry eye is low;the postoperative visual quality is better than LASIK with corneal flap created by microkeratome.

Effect of 2.8mm clear corneal incisions in phacoemulsification on surgically induced corneal higher-order aberrations / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To compare the changes of surgically induced corneal higher order aberrations after phacoemulsification with 2.8mm clear corneal incisions at different sites.METHODS:The clinical data of 100 cases (100 eyes) of patients with cataract treated by phacoemulsification with 2.8mm clear corneal incision in our hospital from March 2015 to April 2016 were analyzed retrospectively.According to the site of incision,they were divided into Group A (temporal clear corneal incision,n =55) and Group B (upper clear corneal incision,n=45).Changes of the best corrected visual acuity (BCVA),surgically induced astigmatism (SIA) and corneal topography were compared between the two groups before surgery,at 1d,1wk,1 and 3mo after surgery.The corneal wavefront aberrations were measured by wavefront aberration analyzer,and the changes of higher-order aberrations in corneal 6mm range were recorded.RESULTS:The BCVA of two groups decreased at 1d,1wk,1 and 3mo after surgery (P＜0.05),and the BCVA of Group A at 1d,1wk,and 1mo after surgery was lower than that of Group B (P＜0.05).SIA of the two groups decreased at 1wk,1 and 3mo after surgery (P＜0.05),and the SIA of Group A at different time points after surgery were lower than those of Group B (P＜0.05).The surface asymmetry index (SAI) and the surface rule index (SRI) of the two groups increased at 1 d after surgery,and were gradually decreased at 1wk,1 and 3mo after surgery.The SRI and SAI in Group A were lower than those in Group B at 1d and 1wk after surgery (P＜ 0.05).The total corneal higher-order aberrations (tHOAs) and four-order spherical aberration (SA)showed significant differences between the two groups at 3mo after surgery (P＜0.05).CONCLUSION:The application of 2.8mm temporal clear corneal incision in phacoemulsification can promote the recovery of visual acuity,reduce the effect of surgery on corneal shape,and reduce corneal higher-order aberrations.

Wavefront-guided Versus Standard Laser in situ Keratomileusis in Myopia Using a 213 nm Wavelength Solid-state Laser: Comparison of Higher-order Aberrations.

Purpose: To assess the accuracy, efficacy, stability and safety of laser in situ keratomileusis (LASIK) for myopia and compare the pre- and post-operative changes in higher-order aberrations after wavefront-guided (WF) and standard (STD) LASIK done using the Pulzar Z1, a 213-nm wavelength solid-state laser, and determine their effects on visual acuity and refractive outcomes. Methods: This a retrospective case series composed of 80 eyes (40 patients) that had LASIK in an out-patient refractive surgery center in Manila, Philippines. Outcome measured were pre and post-operative manifest refraction spherical equivalent (MRSE), uncorrected distance visual acuity (UDVA), best-corrected distance visual acuity (CDVA), keratometry, root-mean-square (RMS) values, flap and ablation related complications. Results: The mean UDVA improved from 20/400 pre-operatively to 20/25 post-operatively. Thirty six of the 40 eyes (90%) treated with STD LASIK and 39 of the 40 eyes (97.5%) treated with WF LASIK had UDVA of 20/30 or better at 1 year post-operatively. There was a significant decrease in spherical equivalent manifest refraction post-operatively in all patients. The average spherical equivalent at 1 year is -0.43D±0.64. After twelve months of follow-up, 85.5% (34 out of the 40 eyes) of those who underwent STD LASIK and 77.5% (31 out of 40 eyes) who underwent WF LASIK had postoperative manifest refractive spherical equivalent (MRSE) of -1.0 to +1.0D. The mean difference in the attempted versus achieved refraction was not significant between the 2 groups (p = 0.32). At 12 months post-operatively, seven eyes (17.5%) gained 1 line in the WF-guided LASIK, while the rest of the eyes either showed no change in CDVA or lost 1-2 Snellen lines. The total RMS generally increased postoperatively for WF LASIK while decreased for STD LASIK, but the mean RMS difference from the pre- and post-operative values between the 2 groups were not statistically significant. None of the eyes developed flap complications during the follow-up period. Conclusion: Refractive surgery using the Pulzar Z1 213-nm wavelength solid-state laser is an effective and safe procedure in the treatment of myopia. Wavefront-guided LASIK offers no advantage over STD LASIK in improving higher-order aberrations and in achieving better visual and refractive outcomes.

Effects of Continuous Curvilinear Capsulorhexis, Intraocular Lens Decentration and Tilt on Clinical Outcomes

PURPOSE: To evaluate the effects of continuous curvilinear capsulorhexis, intraocular lens (IOL) decentration and tilt on postoperative clinical outcomes after cataract surgery. METHODS: We reviewed 62 eyes of 52 patients who underwent cataract surgery and measured the uncorrected visual acuity, best corrected visual acuity and manifest refraction preoperatively and 3 months postoperatively. IOL decentration on anterior segment photography and IOL tilt on anterior optical coherent tomography were analyzed and correlations of postoperative uncorrected visual acuity, best corrected visual acuity, and higher order aberrations were evaluated. In addition, we inspected the relationship of size and decentration of continuous curvilinear capsulorhexis (CCC) intraoperatively with the change in IOL position postoperatively. RESULTS: The average size of CCC was 5.40 ± 0.51 mm (4.12-6.24 mm) and the average decentration of CCC was 0.30 ± 0.19 mm (0.09-1.21 mm) intraoperatively. The average decentration of IOL was 0.23 ± 0.15 mm (0.00-0.71 mm) and the average IOL tilt was 1.43 ± 0.73° (0.00-4.22°) postoperatively. Intraoperative CCC size and decentration were associated with postoperative IOL decentration (p = 0.01, p < 0.001), but not with IOL tilt (p = 0.69, p = 0.52). There were no significant correlations between IOL decentration and tilt with postoperative visual outcomes and higher order aberrations. CONCLUSIONS: The CCC size and decentration can affect the IOL decentration, but IOL decentration and tilt do not have a significant impact on clinical outcomes after cataract surgery.

Effects of Continuous Curvilinear Capsulorhexis, Intraocular Lens Decentration and Tilt on Clinical Outcomes

PURPOSE: To evaluate the effects of continuous curvilinear capsulorhexis, intraocular lens (IOL) decentration and tilt on postoperative clinical outcomes after cataract surgery. METHODS: We reviewed 62 eyes of 52 patients who underwent cataract surgery and measured the uncorrected visual acuity, best corrected visual acuity and manifest refraction preoperatively and 3 months postoperatively. IOL decentration on anterior segment photography and IOL tilt on anterior optical coherent tomography were analyzed and correlations of postoperative uncorrected visual acuity, best corrected visual acuity, and higher order aberrations were evaluated. In addition, we inspected the relationship of size and decentration of continuous curvilinear capsulorhexis (CCC) intraoperatively with the change in IOL position postoperatively. RESULTS: The average size of CCC was 5.40 ± 0.51 mm (4.12-6.24 mm) and the average decentration of CCC was 0.30 ± 0.19 mm (0.09-1.21 mm) intraoperatively. The average decentration of IOL was 0.23 ± 0.15 mm (0.00-0.71 mm) and the average IOL tilt was 1.43 ± 0.73° (0.00-4.22°) postoperatively. Intraoperative CCC size and decentration were associated with postoperative IOL decentration (p = 0.01, p < 0.001), but not with IOL tilt (p = 0.69, p = 0.52). There were no significant correlations between IOL decentration and tilt with postoperative visual outcomes and higher order aberrations. CONCLUSIONS: The CCC size and decentration can affect the IOL decentration, but IOL decentration and tilt do not have a significant impact on clinical outcomes after cataract surgery.

Relationship between Dry Eye Parameters and Anterior Corneal Higher-Order Aberrations Measured by Two Different Instruments

PURPOSE: To compare the corneal first surface higher-order aberrations (HOAs) of normal subjects and patients with dry eye using KR-1W(R) (Topcon Corp., Tokyo, Japan) and Pentacam(R) HR (Oculus Inc., Dutenhofen, Germany). We analyzed the relationship between the aberrations and the diagnostic parameters of dry eye. METHODS: We evaluated anterior corneal HOAs in 71 normal eyes and 71 dry eyes using KR-1W(R) and Pentacam(R). Dry eye patients were examined for fluorescein staining, tear break-up time (TBUT), and Schirmer I test. Ocular Surface Disease Index (OSDI) was used for assessment of subjective symptoms in dry eye patients. RESULTS: HOAs measured by both instruments were greater in the dry eye group than in the control group, although HOAs using KR-1W(R) only achieved statistical significance. The anterior corneal HOAs measured by the 2 instruments were significantly correlated with superficial punctate keratitis. Moreover, TBUT and the Shirmer I test negatively correlated, and OSDI positively correlated, with anterior corneal HOAs. CONCLUSIONS: The HOAs in patients with dry eye were significantly different from controls and tended to increase with disease severity. KR-1W(R) might be more useful than Pentacam(R) to detect tear film instabilities.

Comparison of Corneal Higher-Order Aberrations Measured with Two Instruments Using Scheimpflug Camera System

PURPOSE: To compare the corneal higher-order aberrations (HOAs) of normal young subjects using Galilei(TM) G4 (Zeimer, Port, Switzerland) and Pentacam(R) (Oculus Inc., Wetzlar, Germany). METHODS: Corneal HOAs were measured using Galilei(TM) G4 and Pentacam(R) in 41 healthy individuals (41 eyes). Intraclass correlation coefficients (ICCs) were obtained to evaluate the repeatability of the 2 devices. Differences in HOAs between the 2 instruments were analyzed with a paired t-test and correlations evaluated. RESULTS: All ICCs measured using Galilei(TM) G4 and Pentacam(R) showed more than moderate repeatability (>0.81) except trefoil, tetrafoil, 4th and 5th HOAs. When comparing the measurements obtained with Galilei(TM) G4 and Pentacam(R), total HOAs, spherical aberration (SA), secondary astigmatism and 5th total HOAs were statistically significantly different between the 2 device (all p < or = 0.001). In addition, Galilei(TM) G4 and Pentacam(R) showed discrepancy among all corneal HOAs items. Although the total corneal HOAs and the SA were significantly correlated, other HOA measurements generally exhibited a low correlation. CONCLUSIONS: Corneal HOAs obtained by the 2 instruments cannot be used interchangeably due to their differences and discrepancy although corneal HOAs measured using Galilei(TM) G4 and Pentacam(R) showed relatively high repeatability.

Comparison of higher-order aberration changes in anterior corneal surface between FS-LASIK and SMILE surgery / 安徽医科大学学报

84 eyes that underwent femtosecond laser-assisted laser in situ keratomileusis ( FS-LASIK) , and 110 eyes that underwent small incision lenticule extraction ( SMILE) surgery were included in this prospective case se-ries study. HOAs included ( total HOAs, spherical aberration, horizontal coma aberration, and vertical coma aber-ration) were measured preoperatively after 1 week, 1 month , and 3 months postoperatively by Pentacam. The ab-errations were described as Zernike polynomials. Significantly increased total HOAs and SA and significantly de-creased vertical coma were noted at 1 week, 1 month, and 3 months after FS-LASIK ( P<0.05 ) . However, no significant increase was found in postoperatively horizontal coma. There were significant increases in total HOAs, SA, and horizontal coma and a decrease in the vertical coma at each postoperative examination in SIMLE group ( P<0.05 ) . The total HOAs and SA were significantly smaller in SMILE group than that in FS-LASIK group at 1 week, 1 month, and 3 months postoperatively. The changes in total HOAs and SA were also significantly smaller in SMILE group than that in FS-LASIK group at each postoperative examination. Compared with FS-LASIK, SMILE can induce fewer total higher-order aberrations and spherical aberration after operation.

Comparison of Higher Order Aberrations and Astigmatism after On-Axis Small Incision Cataract Surgery

PURPOSE: To assess the changes of corneal astigmatism and higher order aberrations (HOAs) of the anterior and posterior corneal surface after cataract surgery with on-axis clear corneal incision in eyes with-the-rule (WTR) astigmatism and against-the-rule (ATR) astigmatism. METHODS: This study included 50 patients who underwent phacoemulsification and IOL insertion through a 2.8-mm on-axis clear corneal incision. The eyes were divided into two groups: (1) 26 eyes with WTR astigmatism with a superior incision and (2) 24 eyes with ATR astigmatism with a temporal incision. During the follow-up period, visual acuity was measured, and the surgically induced astigmatism (SIA) and HOAs of the anterior and posterior corneal surface were measured with Pentacam(R) (Occlus, Wetzlar, Germany) preoperatively and 1 week, 1 month, and 2 months postoperatively. RESULTS: There were no significant differences in UCVA and BCVA between the two groups. HOAs increased in both groups 1 week after surgery, but no significant differences were found between the groups (p > 0.05). Surgically induced astigmatism was larger in the WTR group than in the ATR group (p < 0.05). At postoperative 2 months, there were significant differences in HOAs between the two groups, and there were statistically significant differences in HOAs, oblique trefoil at front side, and in HOAs, horizontal coma at rear side (p < 0.05). CONCLUSIONS: In conclusion, superior incision in eyes with WTR astigmatism resulted in higher SIA compared to temporal incision in eyes with ATR astigmatism. Moreover, HOAs was significantly decreased in eyes with WTR astigmatism with superior incision. Thus, superior incision could be more effective in reducing corneal astigmatism in eyes with WTR astigmatism.

Comparison of Keratometry and Corneal Higher Order Aberrations between Scout Videokeratoscope and Pentacam Scheimpflug Camera

PURPOSE: To investigate the correlations of keratometry and corneal high order aberrations (HOAs) between the Keratron Scout videokeratoscope and the Pentacam HR Scheimpflug camera. METHODS: From December 2012 to February 2013, keratometry and corneal HOAs were determined using the Keratron Scout videokeratoscope and Pentacam HR Scheimpflug camera in 23 healthy individuals (46 eyes). RESULTS: Average keratometry showed high correlation with 95% confidence interval -0.155 +/- 0.37 between the Keratron Scout and Pentacam HR. When comparing HOAs of the Keratron Scout and total corneal HOAs of Pentacam HR, total root-mean-square (RMS), and spherical aberration were positively correlated between the 2 devices (r = 0.67, p < 0.001 and r = 0.74, p < 0.001, respectively). When comparing HOAs of Keratron Scout and anterior corneal HOAs of Pentacam HR, total RMS, spherical aberration and coma were positively correlated between the 2 devices (r = 0.62, p < 0.001, r = 0.81, p < 0.001, and r = 0.52, p = 0.047, respectively). CONCLUSIONS: Although the 2 devices are based upon different principles, the Keratron Scout videokeratoscope and Pentacam HR Scheimpflug camera showed positive correlations in keratometry, total RMS, spherical aberration, and coma. Both devices may be useful for clinical applications.