BACKGROUNDAstigmatism is one of the most significant obstacles for achieving satisfactory visual function. This study was to evaluate the influence of astigmatism on contrast sensitivity (CS) and higher-order aberrations.

METHODSCS, accommodation response and wavefront aberration were measured in 113 patients with astigmatism, aged 18 - 36 years. Both single and binocular visual performance were examined under four lighting conditions: photopia, photopia with glare, scotopia and scotopia with glare respectively. Accommodation response was classified as normal, abnormal and low. The contribution of the power and axis of astigmatism to CS, accommodation response and wavefront aberration was analyzed.

RESULTSAs the dioptric power of astigmatism increased, the loss of CS spatial frequency changed from high to intermediate, and then to low frequency. CS scores varied at different illuminance levels, descending in the following sequence: photopia, photopia with glare, scotopia, and scotopia with glare. However, the normal accommodation group showed better CS values under photopia with glare than without glare. The range of influenced direction of sine-wave gratings remained mostly at the meridian line of high dioptric power, which would be expanded when optical accommadation attenuated. The patients with symmetrical astigmatism got higher CS scores with binoculus vision than with dominant eye vision, while the patients with asymmetrical astigmatism did this only at scotopia with glare. Among higher-order aberrations, coma aberration, secondary coma aberration and the total higher order aberration were influenced by astigmatism, all of which rising with the power of astigmatism increased.

CONCLUSIONSReducing astigmatism might improve the performance of visual function. Not only the power of astigmatism should be cut down, but also the binocular axes should be made symmetrically.

Adolescent ; Adult ; Astigmatism ; physiopathology ; Contrast Sensitivity ; Female ; Humans ; Male ; Vision, Ocular

Under the postulation that the double Ruiz procedure could increase the effect of radial keratotomy (RK), RK combined with horizontal and vertical Ruiz procedure was performed in three groups of 22 rabbit eyes. In the group A of six eyes, RK with vertical Ruiz procedure was performed, and eight weeks later horizontal Ruiz procedure was added. In the group B of eight eyes, RK with horizontal Ruiz procedure was performed, and four weeks later vertical Ruiz procedure was added. In the group C of eight eyes, RK with horizontal and vertical Ruiz procedure was performed simultaneously. As a control, in the group D of eight eyes, RK without Ruiz procedure performed. Changes in keratometry for four weeks and eight weeks postoperatively were analyzed. The results were as follows: 1. At eight weeks postoperatively, mean changes in keratometry were 6.434D, 3.663D, 4.030D and 1.585D in groups A, B, C and D, respectively. 2. Mean changes in keratometry of groups A, B and C were significantly higher than that of group D. 3. Mean changes in keratometry of 6.434D in group A was significantly the highest of the three groups in which double Ruiz procedure was performed. For the above results, it was concluded that double Ruiz procedure increased the effect of RK, and the procedure was more effective when the secondary Ruiz procedure was added eight weeks later.
Animals ; Astigmatism ; Cornea/*pathology/physiopathology ; Keratotomy, Radial/adverse effects/*methods ; Rabbits ; Time Factors

OBJECTIVETo evaluate the static and dynamic contrast sensitivity changes in myopic patients before and after laser in situ keratomileusis (LASIK).

METHODSSeventy-three eyes in 37 patients with myopia (with or without astigmatism) who received LASIK were tested for static and dynamic contrast sensitivities using the METRO VISION MON ELEC I system at 0.7, 1.4, 2.7, 5.5, 11, and 22 cpd and cps prior to LASIK, and at one-, three-, and six-month intervals after LASIK.

RESULTSAll eyes gained naked visual acuity of more than 0.5 after LASIK. The contrast sensitivity was depressed at all frequencies 1 month after LASIK, as compared to one week prior to LASIK. The depression at 2.7, 5.5, 11 (P < 0.01) and 22 cpd (P < 0.05) was statistically significant for static contrast sensitivity, and also at 5.5 (P < 0.01) and 11 cps (P < 0.05) for dynamic contrast sensitivity. Myopic eyes between 6.25 D and 14.0 D, and astigmatic eyes 2 DC and more, suffered more static and dynamic contrast sensitivity depression than the myopic eyes between 1.25 D and 6.00 D and astigmatic eyes less than 2 DC. Contrast sensitivities were improved and exceeded preoperative levels 3 months after LASIK, and improved even more 6 months after LASIK. All sequences were statistically significant for static contrast sensitivity (P < 0.01), while only 2.7, 5.5, and 11 cps were statistically significant for dynamic contrast sensitivity (P < 0.01). The astigmatic eyes 2 DC and more showed less improvement, even below the preoperative level at 1.4 cps of dynamic contrast sensitivity.

CONCLUSIONSWhile temporary depression of contrast sensitivity for myopic eyes after LASIK was seen, contrast sensitivity soon returned to exceed preoperative levels at 3 months after LASIK, while improving even more 6 months after LASIK.

Adolescent ; Adult ; Astigmatism ; surgery ; Contrast Sensitivity ; Cornea ; surgery ; Female ; Humans ; Keratomileusis, Laser In Situ ; Male ; Myopia ; physiopathology ; surgery ; Visual Acuity

To determine if the involuntary contractions of eyelids may have any effects on the development of corneal astigmatism, we performed this prospective study which includes 19 patients with either essential blepharospasm or hemifacial spasm. In hemifacial spasm, the degree of corneal astigmatism was evaluated between two eyes. Then the topographic changes were checked using vector analysis technique before and after passively opening the eyelids. They were also measured before and at 1 and 6 months after the injection of Botulinum toxin. Resultantly, 20 eyes had the with-the-rule (group1) and 9 eyes against-the-rule (group2) astigmatism. In hemifacial spasm, significantly more astigmatism was found at spastic eyes. The corneal topographic changes after passively opening the eyelids showed 10 eyes with the astigmatic shift to the with-the-rule, while the remaining 19 to the againstthe- rule. At 1 month after injection of Botulinum toxin, group 1 showed reduced average corneal astigmatism, whereas group 2 showed increased astigmatism. The astigmatic change vector showed significantly more against-the-rule. In the contrary, 6 months after treatment, corneal astigmatism again increased in group 1 and decreased in group 2. So they took on the appearance of pretreatment astigmatic status eventually. Conclusively eyelids may play an important role in corneal curvature.
Aged ; Astigmatism/*drug therapy/physiopathology ; Blepharospasm/*drug therapy/physiopathology ; Botulinum Toxin Type A/administration & dosage/*therapeutic use ; Cornea/drug effects/physiopathology ; Corneal Diseases/*drug therapy/physiopathology ; Eyelids/drug effects/physiopathology ; Female ; Humans ; Injections ; Male ; Middle Aged ; Time Factors ; Treatment Outcome

PURPOSE: To investigate the changes in corneal higher-order aberration (HOA) during amblyopia treatment and the correlation between HOA and astigmatism in hyperopic amblyopia children. METHODS: In this retrospective study, a total of 72 eyes from 72 patients ranging in age from 38 to 161 months were included. Patients were divided into two groups based on the degree of astigmatism. Corneal HOA was measured using a KR-1W aberrometer at the initial visit and at 3-, 6-, and 12-month follow-ups. Correlation analysis was performed to assess the association between HOA and astigmatism. RESULTS: A total of 72 patients were enrolled in this study, 37 of which were classified as belonging to the higher astigmatism group, while 35 were assigned to the lower astigmatism group. There was a statistically significant difference in success rate between the higher and lower astigmatism groups. In both groups, all corneal HOAs were significantly reduced during amblyopia treatment. When comparing the two groups, a significant difference in coma HOA at the 12-month follow-up was detected (p = 0.043). In the Pearson correlation test, coma HOA at the 12-month follow-up demonstrated a statistically significant correlation with astigmatism and a stronger correlation with astigmatism in the higher astigmatism group than in the lower astigmatism group (coefficient values, 0.383 and 0.284 as well as p = 0.021 and p = 0.038, respectively). CONCLUSIONS: HOA, particularly coma HOA, correlated with astigmatism and could exert effects in cases involving hyperopic amblyopia.
Aberrometry ; Adolescent ; Amblyopia/*physiopathology ; Astigmatism/*physiopathology ; Child ; Child, Preschool ; Corneal Topography ; Corneal Wavefront Aberration/diagnosis/*physiopathology ; Eyeglasses ; Follow-Up Studies ; Humans ; Hyperopia/*physiopathology/therapy ; Retrospective Studies ; Visual Acuity/physiology

PURPOSE: This study was conducted to compare post-operative astigmatic outcomes of two groups, with-the-rule (WTR) and against-the-rule (ATR) astigmatism patients, according to the haptic axis of intraocular lenses (IOLs) inserted in cataract surgery. METHODS: Seventy-two eyes with WTR astigmatism and 79 eyes with ATR astigmatism had cataract surgery through a clear corneal temporal incision. These two groups of eyes were then each divided into 2 groups based on whether the haptic axis of the inserted IOL was at 180degrees or 90degrees. For ATR patients, the outcomes were analyzed according to the three types of IOLs. RESULTS: There was no difference in corneal astigmatism, but WTR patients with a 180degrees haptic axis of the inserted IOL and ATR patients with a 90degrees hepatic axis of the inserted IOL had a significant decrease in postoperative refractive astigmatism (p < 0.05). The changes in ATR astigmatism according to the IOL type were more effective in single-piece acrylic IOLs than in the three-piece polymethylmethacrylate haptic IOL group. CONCLUSIONS: Insertion of the IOL at the 180degrees haptic axis in WTR patients and at 90degrees in ATR patients during cataract surgery may have an effect in reducing pre-existing astigmatism. This observed effect was not consistent among the different types of IOLs.
Astigmatism/classification/*etiology/*physiopathology ; Cataract Extraction/*adverse effects ; Equipment Design ; Humans ; Lens Implantation, Intraocular/*methods ; *Lenses, Intraocular ; *Postoperative Complications ; Treatment Outcome

PURPOSE: To evaluate the effect of epiblepharon surgery on visual acuity and with-the-rule astigmatism in children compared to patients without surgical treatment. METHODS: We undertook a retrospective case control study and reviewed the charts of 202 eyes treated with epiblepharon surgery and of 142 eyes without surgery. The surgical procedure for epiblepharon correction used rotating suture techniques. Data regarding age, best corrected visual acuity, and degree of astigmatism were recorded. Baseline and 1-, 3-, 6-, and 12-month postoperative data were collected. The chi-square test, Student's t-test and general linear model analysis for repeated measures were applied. RESULTS: The mean astigmatism in the surgical group decreased from 1.10 +/- 1.02 diopter (D) preoperatively to 0.84 +/- 1.05 D at 3 months after surgery (p < 0.05). However, there was no statistically significant difference compared to the non-surgical group during the first year. The general linear model analysis comparing the mean astigmatism between the two groups over time showed a significant group-time interaction (p < 0.05). Within the surgical group, the higher baseline astigmatic subgroup and the 5- to 8-year-old group demonstrated greater cylinder reduction over time. The change in mean visual acuity was not significant in either group. CONCLUSIONS: Significant astigmatic reduction was found after surgical correction in epiblepharon patients. Patients with higher baseline astigmatism exhibited greater astigmatic reduction after epiblepharon surgery. These results suggest that, in order to reduce astigmatism, an epiblepharon operation should be considered in patients with a high level of astigmatism.
Astigmatism/*etiology/*physiopathology ; Case-Control Studies ; Child ; Child, Preschool ; Eye Abnormalities/*complications/*surgery ; Eyelashes/pathology ; Eyelids/*abnormalities/pathology/surgery ; Female ; Humans ; Male ; Retrospective Studies ; Treatment Outcome ; *Visual Acuity

PURPOSE: The purpose of this study is to compare the magnitude and axis of astigmatism induced by a combined inferior oblique (IO) anterior transposition procedure with lateral rectus (LR) recession versus LR recession alone. METHODS: Forty-six patients were retrospectively analyzed. The subjects were divided into two groups: those having concurrent inferior oblique muscle overaction (IOOA) and intermittent exotropia (group 1, 20 patients) and those having only intermittent exotropia as a control (group 2, 26 patients). Group 1 underwent combined anterior transposition of IO with LR recession and group 2 underwent LR recession alone. Induced astigmatism was defined as the difference between preoperative and postoperative astigmatism using double-angle vector analysis. Cylinder power, axis of induced astigmatism, and spherical equivalent were analyzed at 1 week, 1 month, and 3 months after surgery. RESULTS: Larger changes in the axis of induced astigmatism were observed in group 1, with 4.5° incyclotorsion, than in group 2 at 1 week after surgery (axis, 84.5° vs. 91°; p < 0.001). However, there was no statistically significant inter-group difference thereafter. Relaxation and rapid regression in the incyclotorsion of induced astigmatism were observed over-time. Spherical equivalent significantly decreased postoperatively at 1 month in both groups, indicating a myopic shift (p = 0.011 for group 1 and p = 0.019 for group 2) but did not show significant differences at 3 months after surgery (p = 0.107 for group 1 and p = 0.760 for group 2). CONCLUSIONS: Combined IO anterior transposition procedures caused an increased change in the axis of induced astigmatism, including temporary incyclotorsion, during the first week after surgery. However, this significant difference was not maintained thereafter. Thus, combined IO surgery with LR recession does not seem to produce a sustained astigmatic change, which can be a potential risk factor of postoperative amblyopia or diplopia compared with LR recession alone.
Astigmatism/diagnosis/*etiology/physiopathology ; Child ; Exotropia/diagnosis/physiopathology/*surgery ; Eye Movements/*physiology ; Female ; Follow-Up Studies ; Humans ; Male ; Oculomotor Muscles/*surgery ; Ophthalmologic Surgical Procedures/*methods ; Retrospective Studies ; Treatment Outcome ; Vision, Binocular/*physiology

PURPOSE: To evaluate the long-term efficacy and rotational stability of the AcrySof toric intraocular lens (IOL) in correcting preoperative astigmatism in cataract patients. METHODS: This prospective observational study included 30 eyes from 24 consecutive patients who underwent implantation of an AcrySof toric IOL with micro-coaxial cataract surgery between May 2008 and September 2008. Outcomes of visual acuity, refractive and keratometric astigmatism, and IOL rotation after 1 day, 1 month, 3 months, and long-term (mean, 13.3+/-5.0 months) follow-up were evaluated. RESULTS: At final follow-up, 73.3% of eyes showed an uncorrected visual acuity of 20/25 or better. The postoperative keratometric value was not different from the preoperative value; mean refractive astigmatism was reduced to -0.28+/-0.38 diopter (D) from -1.28+/-0.48 D. The mean rotation of the toric IOL was 3.45+/-3.39 degrees at final follow-up. One eye (3.3%) exhibited IOL rotation of 10.3 degrees, the remaining eyes (96.7%) had IOL rotation of less than 10 degrees. CONCLUSIONS: Early postoperative and long-term follow-up showed that implantation of the AcrySof toric IOL is an effective, safe, and predictable method for managing corneal astigmatism in cataract patients.
*Acrylic Resins ; Adult ; Aged ; Aged, 80 and over ; Astigmatism/complications/physiopathology/*surgery ; Cataract/*complications/physiopathology ; Cataract Extraction/*methods ; Female ; Follow-Up Studies ; Humans ; *Lenses, Intraocular ; Male ; Middle Aged ; Prospective Studies ; Prosthesis Design ; Refraction, Ocular ; Time Factors ; Treatment Outcome ; Visual Acuity

PURPOSE: To evaluate the changes of refractive astigmatism after horizontal rectus muscle surgery in intermittent exotropic children. METHODS: Sixty-nine exotropic patients were retrospectively reviewed. Of those, 35 patients received unilateral lateral rectus recession (BLR group, 35 eyes) and 34 patients received unilateral lateral rectus recession and medial rectus resection (R&R group, 34 eyes). Non-cycloplegic refractions were measured until 6 months postoperatively. Spherical equivalent (SE), J0 and J45 using power vectors were calculated to determine and compare the changes of refractive astigmatism and axis in both groups. RESULTS: SE significantly decreased after surgery for the first week and did not changed thereafter in both groups (p = 0.000 and p = 0.018, respectively). In BLR group, J0 showed significant changes at the first week and 1 month after surgery (p = 0.005 and p = 0.016, respectively), but in R&R group, J0 changed significantly between 1 week and 3 months postoperatively (p = 0.023 and p = 0.016, respectively). J45 did not change significantly as time passed in both groups (all p > 0.05). There was no statistically significant difference in the magnitude of changes in SE, J0 and J45 between the two groups after the 6-month follow-up (p = 0.500, p = 0.244 and p = 0.202, respectively). CONCLUSIONS: Horizontal rectus muscle surgery in intermittent exotropic children tends to induce a statistically significant change in astigmatism in the with-the-rule direction and myopic shift in SE. This astigmatism change seems to occur within the first 3 months after surgery. Thus, astigmatism induced by surgery should be checked and corrected at least 3 months after horizontal strabismus surgery.
Adolescent ; Astigmatism/*etiology/physiopathology ; Child ; Child, Preschool ; Exotropia/complications/physiopathology/*surgery ; *Eye Movements ; Female ; Follow-Up Studies ; Humans ; Male ; Oculomotor Muscles/surgery ; Ophthalmologic Surgical Procedures/*methods ; Retrospective Studies ; Treatment Outcome ; Vision, Binocular/*physiology