Objectives: To compare the vector analysis, visual, and refractive outcomes of femtosecond-assisted laser insitu keratomileusis (LASIK) and small incision lenticule extraction (SMILE) among myopic patients with moderate myopic astigmatism. Methods: This was a single-center, retrospective, cohort study that compared eyes that underwent femtosecond LASIK or SMILE for the correction of myopia and astigmatism of 0.75 to 3.0 diopters. Vector analysis and standard graphs for reporting visual and refractive outcomes were utilized for analysis. Results: There were 82 femtosecond LASIK-treated eyes and 80 SMILE-treated eyes with similar preoperative characteristics except for slightly higher mean preoperative sphere refraction in the SMILE group (-4.2±2.4 D vs -4.9±1.6 D, p=0.03). At 3 months, femtosecond LASIK group had better mean uncorrected distance visual acuity (UDVA) (LogMAR 0.006±0.06 vs 0.06±0.09, p=0.00) and had more eyes achieving postoperative UDVA of 20/20 or better (88% versus 56%). Although there were similar postoperative spherical equivalents, residual astigmatism was higher in the SMILE group (0.11±0.22 D vs 0.32±0.30 D, p=0.00). Vector analyses showed significantly better outcomes for femtosecond LASIK than for SMILE in terms of difference vector (DV), index of success (IOS), torque, and flattening index (FI). A trend for undercorrection for higher astigmatism was seen in both groups that was greater in the SMILE group. Both groups showed high safety with the majority of eyes showing postoperative corrected distance VA (CDVA) within 1 line of preoperative CDVA (98.8% versus 91.2%). Conclusion Although femtosecond LASIK and SMILE have similar predictability at 3 months, femtosecond LASIK has relatively better efficacy and superior astigmatic outcomes than SMILE for the correction of moderate myopic astigmatism.
Astigmatism

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.
Astigmatism ; Lotus

To evaluate surgically induced astigmatism for 6 months following 3.2mm scleral tunnel incision cataract surgery according to incision site we divided 115 patients(124 eyes) into superior incision group 1 (58 eyes) and superotemporal incision group 2 (66 eyes). Each group was classified into 3 cases according to preoperative astigmatism. Postoperative astigmatic changes by vector method were 0.40 diopter(D) against-the-rule astigmatism(ATR) in group 1, 0.25 D ART in group 2 at 6 months and there was no difference between two groups(P>0.05). In the preoperative with-the-rule astigmatic cases, postoperative astigmatic changes were 0.56 D ART in group 1, 0.38 D ATR in group 2, in the preoperative against-the-rule astigmatic cases, postoperative astigmatic changes were 0.25 D ART in group 1, 0.12 D ART in group 2, in the preoperative no astigmatic cases, postoperative astigmatism changes were 0.53 D ATR in group 1, 0.25D ART in group 2 at 6 months. There was no significant difference between two groups in postoperative astigmatic changes(P>0.05) and corneal astigmatisms were stabilized after 2 months postoperatively in both groups(P<0.05).
Astigmatism* ; Cataract*

A survey on the myopia in 579 pupils of 2 primary schools o Tan Mai and Van Noi in Ha Noi was carried out. Results showed that: light intensity was at the hygienic standard, but in some sitting places the ligh intensity was too high. The height of the desks were not compatible with the height of the pupils. The poor vision was 17%, the refraction problem was 24%, hypermetropic myopic astigmatism were 11%, some influence factors to vision disorder of the pupils were found out initially. The vision disorder of the pupils at Tan Mai school was significant higher than this in Van Noi school.
Myopia ; Astigmatism

Objective: To determine the effect of corneal collagen cross-linking on the corneal curvature of eyes with keratoconus measured using an Oculus Pentacam® at 2 years and annually thereafter. Methods: This was a descriptive, retrospective study involving patients with keratoconus who had undergone uncomplicated collagen cross-linking using the Dresden protocol from January 2012 to March 2016. Baseline measurements of best-corrected visual acuity (BCVA), maximum K value (Kmax), corneal astigmatism, anterior and posterior elevation map changes were recorded and compared with data taken at 2 and 3 years Results: This study included 32 patients (48 eyes) with a mean follow-up of 28.88 ± 6.23 months. Only 4 patients (6 eyes) had 3-year follow-up data with a mean follow-up of 42.83 ± 4.58 months. When all eyes were considered, significant changes were noted in Kmax, BCVA, and anterior and posterior elevation maps between baseline and 2-year follow-up. Specifically, there were significant decreases in Kmax (p<0.0001) and anterior elevation (p<0.05), and significant improvement in BCVA (p<0.01) while posterior elevation (p<0.0001) was found to have increased significantly at 2nd year follow-up compared to baseline. When only eyes with 3-year follow-up data was analyzed, only BCVA showed significant change (p<0.05). Corneal astigmatism remained stable during the study period. Conclusion Two to 3 years after collagen cross-linking for keratoconus, corneal curvature parameters and BCVA showed improved and stable outcomes when compared to baseline.
Keratoconus ; Astigmatism

Management of surgically induced astigmatism is the major problem for surgeons implanting intraocular lenses. Besides corneal astigmatism, the fixation status of the intraocular lens(IOL) may contribute to postoperative astigmatism. This study was undertaken to analyze whether the variable factors such as fixation status, IOL type, and capsulotomy method affect tilting and decen tration of IOL. The tilting angle and decentration of the IOL were measured by image-processing technique using computerized Scheimpflug camera. The average tilting angle was 4.30 +/- 2.21 degree. The average decentration was 0.44 +/- 0.36mm from the corneal center. Based on these data, the astigmatic error induced by the tilting and/or decentration of the implanted IOL was calculated as within 0.1 diopter. Haptic fixation and designs were statistically significant for IOL posit ion but tilting and decentration were not significantly associated with capsulotomy method, agegroup, sex, and postoperative day.
Astigmatism* ; Lenses, Intraocular

PURPOSE: The effect of superior clear corneal incision and transverse astigmatic keratotomy on the with-the-rule astigmatism in sutureless, small incision cataract surgery was evaluated. METHODS: The postoperative keratometric changes were evaluated in 18 eyes with more than 1.4 diopter (D) of preoperative with-the-rule astigmatism, having sutureless, superior clear corneal incision phacoemulsification. Five eyes over 2.8 D with-the-rule astigmatism also had transverse corneal relaxing incision. Keratometric readings were done within 1 month preoperatively, 1 day and 2 months postoperatively and the changes were statistically analyzed. Simple subtraction method and Cravy method were used for the analysis of astigmatic changes. RESULTS: The mean astigmatism showed decreasing trend, 2.08, 2.25, 1.12 D, within preoperative 1 month, at postoperative 1 day and 2 months respectively and 3.70, 2.48, 2.06 D respectively when transverse keratotomy was added. The reduction of astigmatism was statistically significant at postoperative 2 months (P<0.05; Wilcoxon rank-sum test) and it was more significant with transverse astigmatic keratotomy (P<0.05, Mann-Whitney U test). CONCLUSIONS: The with-the-rule astigmatism over 1.40 D could be reduced in cataract surgery by sutureless, superior clear corneal incision and transverse corneal relaxing keratotomy.
Astigmatism* ; Cataract* ; Phacoemulsification ; Reading

A large amount of corneal astigmatism after penetrating keratoplasty is a common problem. The purpose of this study was to find out which is the best suture method to minimize the postoperative corneal astigmatism. Among 35 eyes there were 7 eyes in interrupted suture group, 14 eyes in continuous suture group, and 14 eyes in combined suture group. In order to minimize postoperative astigmatism selective suture removal was done in interrupted suture group or combined suture group, and suture tension adjustment was made in continuous suture group. At postoperative 20 months the mean astigmastism was 5.97D in interrupted suture group, 3.66D in continuous suture group and 2.87D in combined suture group, respectively. There was no statistical significance. In spite of statistical insignificance, the astigmatism of continuous or combined suture group after penetrating keratoplasty was smaller than that of interrupted suture group after penetrating keratoplasty.
Astigmatism* ; Keratoplasty, Penetrating* ; Sutures*

PURPOSE: We examined changes in the corneal curvature and recurrence rate following pterygium surgery with relation to pterygium size and morphology. METHODS: One hundred eyes with primary nasal pterygia were graded as atrophic(Group 1), intermediate (Group 2), or fleshy(Group 3) according to morphology and grouped as small area group or large area group according to an assessment of pterygium length from and along the limbus. Corneal curvature was measured with autokeratometer at 3 days, 1 week, 1 month, and 6months preoperatively and postopera-tively as well. Recurrence was evaluated at the same periods. RESULTS: Each group had no significant difference(p>0.05) to preoperative corneal curvature when pterygia were divided according to morphology. Large area group had significantly smaller corneal curvature than the preoperative one(p<0.05), but small area group didn't(p>0.05). The angle of astigmatism had the tendency of against-the-rule at 3 days postoperatively(163.3degrees), more strikingly in small area group(159.1degrees). The recurrence rate was 10% totally with no significant difference among each group(p>0.05). CONCLUSIONS: The magnitude of the corneal curvature following pterygium surgery was smaller than the preoperative one and the change of angle had the tendency of against-the-rule astigmatism. Surgically induced changes in the corneal curvature and recurrence rate related to morphology had no significant difference, but preoperative corneal curvature and postoperative changes were related to pterygium size.
Astigmatism ; Pterygium* ; Recurrence*

We evaluated the corneal topography of 109 eyes which have 1 diopter or more astimatism, with computer-assisted videokeratography(Eye Sys CAS). There was 11% with round pattern, 17.4% with oval pattern, 49.5% with symmetric bow-tie pattern, 19.3% with assymmetric bow-tie pattern, 2.8% with irregular pattern. 70% of subjects had right and left eyes classified into the same group. There was statistically significant difference among the patterns for keratometric astigmatism and difference among the groups which were classified by the location of the area of highest refractive power for keratometric and total astigmatism. The mean angular separation between flat and steep meridian was 89.2 degrees and ranged from 78.61 degrees to 100.67 degrees. The mean residual astigmatism was 0.547 diopter. In the with-the rule astigmatism type, when the total astigmatism less than 1.89 diopter, residual astigmatism neutralize the corneal astigmatism, but when the total astigmatism increase more than 1.89 diopter, residual astigmatism tend to increase the total astigmatism.
Astigmatism* ; Classification* ; Corneal Topography*