ABSTRACT
AIM:To investigate the correlation between corneal biomechanical parameters measured by the corneal visualization Scheimpflug Technology(Corvis ST)and corneal high-order aberrations(HOAs)in children with mild to moderate myopia.METHODS:A cross-sectional study. A total of 255 pediatric patients with myopia enrolled from April to July 2021 in Tianjin Medical University Eye Hospital were continuously collected, and all the right eyes were taken for analysis. Corneal biomechanical parameters were obtained from Corvis ST. Pentacam three-dimensional anterior segment analyzer was used to measure total corneal higher-order aberrations(RMSh), third order aberrations(RMS3)and fourth order aberrations(RMS4).RESULTS:RMS3 was positively correlated with the second applanation time(A2T)(r=0.175, P=0.009)and negatively correlated with the axis length(AL)(r=-0.155, P=0.014). RMS4 was negatively correlated with the highest concavity radius(HCR)(r=-0.165, P=0.009). RMSh was negatively correlated with HCR and AL(r=-0.152, P=0.037; r=-0.175, P=0.005).CONCLUSION:There is a correlation between corneal biomechanical parameters and HOAs in children with myopia. Cornea with higher stiffness and stronger deformation resistance has smaller RMS3, RMS4 and RMSh.
ABSTRACT
@#AIM: To observe the high-order aberrations, diopters, ocular structural parameters and their correlation in adolescents with high myopia.<p>METHODS: Cross sectional study. Totally 116 adolescent high myopia patients(116 eyes)were selected from the Center of Optometry of the First Affiliated Hospital of Harbin Medical University on July 9, 2019. The axial length and intraocular pressure were measured. The high-order aberrations(RMSg, RMSh, Z22, Z33, Z31,Z40,RMS3-RMS7), corneal curvature(minimum K1, maximum K2, average km), central cornea thickness(CCT), anterior chamber depth(ACD)and anterior chamber angle(ACA)were measured with Sirius three-dimensional anterior segment analyzer. The correlation between the above eye parameters was analyzed.<p>RESULTS: There was a significant negative correlation between diopter and axial length(<i>r</i>= -0.400, <i>P</i><0.001); a positive correlation between axial length and anterior chamber depth(<i>r</i>= 0.433, <i>P</i><0.05), a negative correlation between axial length and corneal curvature(K1, K2, Km)(<i>P</i><0.05); a negative correlation between total higher-order aberrations and diopter(<i>r</i>=-0.189, <i>P</i><0.05), which was negatively correlated with the axial length(<i>r</i>=-0.228, <i>P</i><0.05). There was no correlation between the higher-order aberrations and the sphericity(<i>P</i>>0.05), Z40 was positively correlated with the corneal curvature(K1, K2, Km)(<i>P</i><0.05), and no correlation between higher-order aberrations and CCT, ACD, ACA was found.<p>CONCLUSION: With the increase of myopia degree, the axial length and total higher-order aberrations of adolescent high myopia increase, and the total higher-order aberrations are negatively correlated with the axial length. The increase of axial length may be a compensatory way to reduce the high-order aberrations and promote the development of myopia.
ABSTRACT
@#AIM: To analyze the early visual quality differences of femtosecond laser small incision matrix lens extraction(SMILE)versus femtosecond laser excimer laser <i>in situ</i> keratomileusis(LASIK).<p>METHODS: From February 2017 to February 2018, 78 patients(including 156 eyes)with SMILE myopia were enrolled in our hospital. Eighty patients(160 eyes)who underwent LASIK myopia in the same period were selected. All patients were followed up for three times. Months were observed for surgical outcomes, high-order aberrations, and contrast sensitivity(CS)status.<p>RESULTS: At 1mo and 3mo postoperatively, the central corneal thickness change rate in the SMILE group was(-14.48±2.67)%,(-13.54±2.90)% lower than that of LASIK(-17.92±2.85)%,(-15.63±2.71)%, and intraocular pressure changes. The rates were(-27.08±3.64)% and(-24.41±3.28)% were lower than those in the LASIK group(-29.26±3.81)% and(-27.01±3.62)%(<i>P</i><0.05). The total high-order aberrations of the SMILE group were the sputum difference was lower than that of LASIK group(<i>P</i><0.05). The SMILE group values were(1.86±0.21),(1.52±0.23)and(0.91±0.14)when the spatial frequency of glare CS was 1.5, 12.0 and 18.0 at 1mo after operation was higher than the LASIK group(1.71±0.20),(1.41±0.25),(0.81±0.12)(<i>P</i><0.05).<p>CONCLUSION: SMILE has a lower effect on patients with higher-order aberrations than LASIK, and the early visual quality is better.
ABSTRACT
@#AIM: To evaluate the clinical efficacy of femtosecond laser-assisted cataract surgery combined with trifocal intraocular lens(IOL)implantation.<p>METHODS:From September 2016 to November 2017, 42 cases(59 eyes)of cataract patients receiving trifocal IOL implantation in Shanxi Eye Hospital were retrospectively enrolled in this study. Moreover, the visual and refractive outcomes, defocus curve, refractive stability, high order aberrations, patient satisfaction, and spectacle independence were evaluated at 1wk, 1mo, 3mo and 6mo after surgery, respectively.<p>RESULTS: All patients had attained good visual acuity of >0.1 LogMAR at different distances during the follow-up period; besides, the visual acuity at each distance was remarkably higher compared with that before surgery(<i>P</i><0.05). The defocus curve had displayed no significant decrease between 0D to -2.5D at 6mo postoperatively, with the visual acuity better than 0.8. At 6mo postoperatively, 63%(37 eyes)eyes had a spherical equivalent(SE)of ±0.25D, and 88%(52 eyes)eyes had a SE of ±0.50D. The incidences of high order aberrations, coma, spherical aberration and trefoil of all eyes were evidently lower than those before surgery, and the difference was statistically significant(<i>P</i><0.05). <p>CONCLUSION: Femtosecond laser-assisted cataract surgery combined with trifocal IOL implantation can provide patient with a comfortable and natural full-range vision, which can greatly improve the postoperative satisfaction of patients.
ABSTRACT
Background Cornea astigmatism can be effectively corrected by implanting Toric intraocular lens (IOL) during cataract surgery and therefore improve visual acuity of patients.However,the decentration and rotation position errors were inevitable sometime.What's the difference of effect of position errors on quality of image between spherical IOL and Toric IOL needs further research.Objective This study was to evaluate the optical performance and wavefront with rotation and decentration of Toric IOL.Methods Different decentration for SN60AT IOL(spherical IOL) and Toric IOL in Hwey-Lan Lion model eyes was set with the role as follows:decentration 0.25 mm to 0.75 mm in a 5°-interval from 0° to 90°.Furthermore,Toric IOL was rotated at 5° and 10°,respectively.Then the image performances of SN60AT IOL and Toric IOL at different decentration distances and rotated degrees were evaluated with modulation transfer function (MTF) and value of wavefront aberration under all conditions.Results At the centration,the MTF curves of spherical IOL and Toric IOL were similar under 3,4 and 5 mm pupil diameter at each spatial frequency.Under the condition of 4 mm pupil diameter,when the decentration was 0.25 mm,the MTF values of SN60AT IOL at 6 c/d and 12 c/d were 0.581 087 and 0.411 960,respectively.T3 IOL were 0.454 259 and 0.382 313,T4 IOL were 0.426 020 and 0.360 490,T5 IOL were 0.425 606 and 0.359 877.When the decentration was 0.50 mm,the MTF values of SN60AT at 6 c/d and 12 c/d were 0.573 073 and 0.412 787,respectively.T3 IOL were 0.450943 and 0.379481,T4 IOL were 0.423 153 and 0.356 664,T5 IOL were 0.422 881 and 0.356 230.When the decentration was 0.75 mm,the MTF values of SN60AT at 6 c/d and 12 c/d were 0.560 038 and 0.413 624,respectively.T3 IOL were 0.445 597 and 0.374 322,T4 IOL were 0.418 522 and 0.350 087,T5 IOL were 0.418 468 and 0.349 976.When the IOL decentralized along 0°,5°,10°,90°meridian line,the MTF values were almostly same.The root mean square (RMS) of spherical IOL and Toric IOL was increased when the IOL decentralized from 0 mm to 0.75 mm,with the most increasing level in coma aberration and slight increase in trefoil aberration.When the T4 IOL decentralized from centre to 0.75 mm,the coma increased from 0 to C(3,-1)-0.049 79 μm,C (3,1)-0.037 59 μm and the trefoil aberration increased from 0 to C (3,3) 0.005 72 μm,C (3,-3) 0.004 64 μm.With the increase of rotation degrees (from 5°to 10°) of Toric IOL,the MTF was worse at high spatial frequency.Toric IOL rotation caused the increase of astigmatism and residual astigmatism and spherical error,but not high order aberration.Conclusions The tolerance of Toric IOL to decentration is very close to the spherical IOL,and optical performance is only associated with the amount of decentration but not direction.The aberration caused by Toric IOL decentration is mainly coma.The rotation of Toric IOL causes astigmatism error but not high order aberrations.
ABSTRACT
?AIM: To investigate the corneal high order aberrations in adults with myopia and to study its correlations with myopic degree and keratometry.?METHODS: A total of 63 patients ( 126 eyes ) from the ophthalmology department of our hospital were included in this study during May 2014 to June 2015. Visual acuity, intraocular pressure ( IOP ) , diopter, slit lamp examination, central corneal thickness ( CCT ) , funduscopic examination, corneal topography and corneal total higher order aberrations ( THOAs ) were recorded. Right eye was selected. According to the spherical equivalence ( SE) , 63 eyes were divided into two groups, the mild to moderate myopia group (M-M group, SE0. 05 ) Total coma aberration ( TCA ) was negatively correlated with SE (r=-0. 57,P=0. 002) and spherical degree (Sph, r=-0. 55,P=0. 003) in H group. Z40 was positively correlated with average K (AK) (M-M group:r=0. 40,P=0. 02. H group:r=0. 55, P=0. 03), K steep (Ks) (M-M group:r=0.39, P=0.02. H group:r=0.51, P=0.01) and K flat (Kf) ( M-M group:r=0. 40, P=0. 02. H group:r=0. 57, P=0. 01) in both groups. Z53was negatively correlated with Ks(r=-0.4, P=0. 04) in H group.?CONCLUSION: The THOAs parameters are influenced by diopter and keratometry. TCA is negatively correlated with SE and Sph in patients with high myopia, and spherical aberration is positively correlated with keratometry.
ABSTRACT
Context: Visual function is determined by a combination of the cornea, which has a larger effect and internal aberrations generated by the intraocular lens and those induced by the surgery. These corneal refractive changes are related to the location and size of the corneal incision. The smaller the incision, the lower the aberrations and the better the optical quality. Aims: To compare the effect of uneventful coaxial versus biaxial microincision cataract surgery (MICS) on the corneal aberrations. Settings and Design: Retrospective interventional nonrandomized comparative case study comprised 40 eyes of 36 patients with primary senile cataract. Subjects and Methods: They were divided into two groups: Group I (20 eyes) had operated by biaxial MICS and Group II (20 eyes) had operated by coaxial MICS. Each group were assessed by corneal topography and wavefront analysis over 6 mm pupil size preoperatively and 1‑month postoperatively. Statistical Analysis Used: Statistical analysis was performed using SPSS for Windows (version 17.0.1, SPSS, Inc.). The paired t‑test was used to compare the mean values of corneal aberrations preoperatively and 1‑month postoperatively in each group. Results: There was a significant increase in trefoil and quatrefoil in biaxial MICS (P = 0.063, 0.032 respectively) while other aberrations insignificantly changed. The coaxial MICS showed a significant increase in root mean square (RMS) of total high order aberrations (HOAs) (P = 0.02) and coma (0.028), but not the others. In comparison to each other, there was the insignificant difference as regards astigmatism, RMS of individual and total HOAs. Conclusions: Coaxial and biaxial MICS are neutral on corneal astigmatism and aberrations.
ABSTRACT
PURPOSE: To determine the power vector and aberrations before and after surgery for pterygium using a corneal topographer and a wavefront aberrometer. METHODS: The study group consisted of 34 eyes of 31 patients with pterygium, and were divided into two groups by pterygium size ( or = 3 mm, group II). Power vector and wavefront aberrations were evaluated using a corneal topographer (Oculus inc., Germany) and a wavefront aberrometer (LADARWAVE(R), Hartmann shack aberrometer, Alcon inc., US) at pre- and postoperative 1 week, 1 month, and 3 months. RESULTS: The preoperative blurring strength (B) and high order aberrations significantly decreased at postoperative 3 months in all groups (P or = 3 mm). To reduce aberrations and astigmatism effectively, we suggested surgical intervention in eyes with pterygia sized < 3.0 mm.
Subject(s)
Humans , Astigmatism , Eye , Preoperative Period , PterygiumABSTRACT
PURPOSE: We evaluate the clinical outcomes after wavefront-guided (WFG) Epi-LASIK in mild and moderate myopia . METHODS: The uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest refraction, total high order aberrations, contrast sensitivity for day and night vision, and pain score in 114 eyes of 61 patients who had undergone WFG Epi-LASIK were measured preoperatively and at 1 day, 1 week, 1 month, 2 months, and 6 months postoperatively. RESULTS: At 1 day, 1 week, 1 month, 2 months and 6 months postoperatively, UCVA & BCVA had improved significantly. At 1 month postoperatively, the spherical equivalent was -0.93+/-0.74 and showed a stable pattern at 6 months postoperatively. There was no statistically significant difference in total high-order aberration between preoperatively measurements and measurements taken at 6 months postoperative (p=0.745). At a frequency of 19 cpd, night contrast sensitivity showed significant statistical difference (p=0.010) but no difference at low and medium frequencies between preoperative measurements and postoperative six months measurements. Pain subsided at 2 weeks postoperative. All patients maintained clear cornea and suffered no complications. CONCLUSIONS: At 6 months postoperatively, patients who underwent Wavefront-guided Epi-LASIK showed successful results for the correction of moderate myopia and excellent contrast sensitivity at night time. Wavefront-guided Epi-LASIK may solve the visual quality problem after refractive surgery and, therefore, may be clinically useful.