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PubMed1996

[Is cranial corneoscleral 6 mm "no-stitch" tunnel incision contraindicated in against-the-rule astigmatism?].

BACKGROUND: There is a risk to increase a preexisting astigmatism against the rule by performing the incision at the 12 o'clock position. PATIENTS AND METHODS: In the prospective study 15 patients with a preoperative astigmatism over 0.25 D axis 90 degrees +/- 15 degrees the first cataract extraction was performed by a cranial, the operation of the other eye by a temporal 6-mm no-stitch tunnel incision. RESULTS: The mean corneal astigmatism against the rule preoperatively was 1.02 +/- 0.5 D with cranial incision and 1.27 +/- 0.8 D with temporal incision. Postoperatively the corneal astigmatism was 2.18 +/- 0.9 D with cranial incision and 0.71 +/- 0.7 D with temporal incision. In comparison to the pre-existing astigmatism, there was an increase of the astigmatism with cranial incision more than double, with temporal incision the astigmatism was significant lowered. Postoperatively the astigmatism with temporal wound location was significant lower than with cranial incision. CONCLUSION: Under the aspect of a 1.5 D higher average astigmatism postoperatively, we conclude that a cranial 6-mm no-stitch tunnel incision in preoperative astigmatism against the rule is contraindicated.

Aged↗
PubMed2001

Laser in situ keratomileusis versus photorefractive keratectomy in the correction of myopic astigmatism.

PURPOSE: To evaluate retrospectively the effectiveness of astigmatism correction in eyes treated with laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). METHODS: Patients with low to moderate myopia with astigmatism ranging from +0.25 to +4.50 diopters were included in the study. PRK was performed on 62 eyes and LASIK on 70 eyes. Six-month data were analyzed with regard to astigmatism power, astigmatism axis, spherical equivalent, uncorrected visual acuity, vector astigmatism change, and topographic corneal regularity. RESULTS: Mean astigmatism magnitude change was 0.54 +/- 0.76 in PRK-treated eyes and 0.60 +/- 0.67 in LASIK-treated eyes (61% versus 64% change, respectively, p = 0.61) at 6 months after surgery. Mean spherical correction change was -2.79 +/- 1.51 for PRK and -2.90 +/- 1.03 for LASIK (p = 0.63). Mean spherical equivalent change was -2.5 +/- 1.57 for PRK and -2.6 +/- 1.23 for LASIK (p = 0.73). Mean change in astigmatism axis was 20.8 +/- 73.1 for PRK and 33.8 +/- 81.7 for LASIK (p = 0.34). Mean change in uncorrected visual acuity (LogMar) was 0.84 +/- 0.26 for PRK and 0.89 +/- 0.23 for LASIK (p = 0.21). Mean vector-corrected astigmatism change was 0.88 +/- 0.66 for PRK and 0.95 +/- 0.59 for LASIK (p = 0.51). Mean vector-corrected astigmatism axis for PRK was 86.9 +/- 59 degrees and for LASIK 83.8 +/- -47.6 degrees (p = 0.75). CONCLUSION: There was no significant difference in astigmatism correction between PRK and LASIK at 6 months after surgery.

Adult↗
PubMed2001

Corneal and refractive error astigmatism in Singaporean schoolchildren: a vector-based Javal's rule.

BACKGROUND: Traditional approaches to Javal's rule do not use data from subjects with oblique astigmatism and have not been used to make predictions about subjects with oblique astigmatism. Vector approaches to analyzing refractive error can circumvent these problems. METHODS: Subjects were 993 Singaporean schoolchildren. We performed linear regression of refractive error astigmatism on corneal astigmatism, using J0 vectors to describe with-the-rule and against-the-rule astigmatism and J45 vectors to describe oblique astigmatism. RESULTS: We obtained the following statistically significant regression relationships: RJ0 = 0.931 x CJ0 - 0.276 and RJ45 = 0.638 x CJ45 + 0.010, where R and C denote refractive error astigmatism and corneal astigmatism, respectively. CONCLUSION: Our vector-based Javal's rule gives closer predictions of refractive astigmatism than the original Javal's rule and the simplified Javal's rule and can be applied in cases of corneal oblique astigmatism.

Adolescent↗
PubMed2005

The association of astigmatism and spherical refractive error in a high myopia cohort.

PURPOSE: The purposes of this study were to determine whether the degree of myopia influences the presence and degree of total astigmatism, and to assess risk factors of astigmatism in patients with familial nonsyndromic severe myopia. METHODS: We performed a retrospective study of 217 subjects from families with two or more subjects from successive generations with a myopic spherical refractive error of at least -5 D or greater in one eye. Mean myopic spherical equivalent was -10 D and the mean age of myopia onset was 7 years. Refractive error measurements were obtained and the association between the degree of myopia and cylinder power was examined by correlation analysis. RESULTS: The prevalence of astigmatism (1.0 D of cylinder) was 36.1%. With-the-rule astigmatism was most common (55.8%), and the majority of astigmats had between 1.0 and 2.5 D of cylinder (77.6%). Statistically significant associations were found between the presence of astigmatism and risk factors of age and the age of myopia onset. In those patients with astigmatism, however, there was a moderate correlation between the degree of spherical equivalent and cylinder power (r = -0.34, p < 0.0001). Younger age (<16 years) (p = 0.03) was associated with higher cylinder power. CONCLUSIONS: In severely myopic patients, there is a high prevalence of astigmatism that is predominantly with-the-rule. The degree of myopic spherical refractive error is correlated with astigmatism severity but is not a risk factor for the presence of astigmatism.

Adolescent↗
PubMed1994

Long-term natural and modified course of surgically induced astigmatism after extracapsular cataract extraction.

A prospective study was carried out to investigate the long-term course of surgically induced astigmatism after extracapsular cataract extraction. Sixty-one eyes were followed for 36 months. In 27 eyes with post-operative astigmatism > 4D with-the-rule, one or two sutures were cut in the steeper meridian after 3 months. In another group of 34 eyes with only minor or no postoperative astigmatism with-the-rule, no suture was cut. We found that 1) postoperative astigmatism was significantly increased in all eyes after 1 week and 3 months, but decreased in time approaching preoperative values after 3 years, 2) surgically induced astigmatism was with-the-rule at 1 week and 3 months but turned against-the-rule in time in both groups. Astigmatism decay rate was significantly steeper in eyes with suture cutting, 3) the keratometric axis was exclusively with-the-rule after 1 week, but turned against-the-rule in both groups, approaching the preoperative distribution of axis after 3 years. We concluded that surgically induced astigmatism is a dynamic feature showing changes in size and axis even in the period 1-3 years postoperatively. Suture cutting seems to intensify the decrease in the induced astigmatism and accelerate the shift in astigmatic axis, turning astigmatism against-the-rule compared to eyes with intact sutures.

Adult↗
PubMed1977

Astigmatism in cataract surgery.

We report on our investigation into astigmatism in 40 eyes following a corneal cataract incision closed with a continuous 10/0 nylon monofilament suture (Ethilon). Immediately after surgery there was astigmatism caused by the nylon suture (suture-induced astigmatism), its severity depending on the tightness of the suture. It ranged from 1 to 10-5 dioptres, the mean value 4-09 dioptres with a standard deviation of +/-2-5. Removing the nylon suture eliminated this astigmatism and within a few weeks the corneal astigmatism correction in 48% of eyes returned to the preoperative level. In 80% of eyes the difference between the final postoperative corneal astigmatism (4 months after removing the continuous suture) and the preoperative astigmatism was 0-75 dioptres or less and the maximum change was 1-5 dioptres. In 40% of eyes the axis of the cylinder changed from a horizontal to an oblique axis but did not change from a with- to against-the-rule axis. The degree of astigmatism remained constant while the suture was in place and in 50% of eyes was equal to or less than 3 dioptres. The mean of the spherical equivalents was 11-31 dioptres with a standard deviation of +/-1-25. A spectacle correction 14 days after operation prescribed either as the mean spherical equivalent (11-50 dioptres) or according to the patient's refraction will give satisfactory vision until the suture is removed 4 months after operation. The degree of astigmatism following a corneal section and continuous nylon suture compares very favourably with astigmatism following other suturing techniques for cataract.

Astigmatism↗
PubMed1998

Clinical evaluation of keratometry and computerised videokeratography: intraobserver and interobserver variability on normal and astigmatic corneas.

AIMS: To evaluate intra- and interobserver variability in measurements on normal and astigmatic corneas with keratometry and computerized videokeratography. METHODS: Keratometric readings with the 10 SL/O Zeiss keratometer and topographic maps with the TMS-1 were obtained by two independent examiners on 32 normal and 33 postkeratoplasty corneas. Inter- and intraobserver coefficients of variability (COR) for measurements of steep and flat meridian power and location, in addition to the magnitude of astigmatism, were assessed. RESULTS: Compared with TMS-1, the 10 SL/O keratometer showed a superior repeatability in measuring normal corneas (intraobserver COR for keratometry and TMS-1 respectively: 0.22 and 0.30 D for steep meridian power; 0.18 and 0.44 D for flat meridian power; 0.26 and 0.40 D for astigmatism; 5 degrees and 26 degrees for steep meridian location; 5 degrees and 13 degrees for flat meridian location). Astigmatism intraobserver COR (0.20 D and 0.26 D for the two observers) and interobserver COR (0.28 D) of the keratometer for normal corneas was very good and not affected by observers' experience. Repeatability of the TMS-1 on normal corneas was found to be: (a) observer related, and (b) astigmatism related. A novice observer showed a much greater COR (1.62 D for astigmatism, 30 degrees for flat meridian location) compared with the experienced examiner (0.40 D for astigmatism, 13 degrees for flat meridian location). Higher deviation scores were observed for corneas with higher astigmatism. For the postkeratoplasty corneas, again the keratometer achieved superior reproducibility (astigmatism interobserver COR 1.12 D for keratometry, 4.06 D for TMS-1; steep meridian location interobserver COR 10 degrees for keratometry, 34 degrees for TMS-1). CONCLUSION: Keratometric readings are more reproducible than topographic data both for normal and postkeratoplasty corneas. The two instruments should not be used interchangeably especially on highly astigmatic corneas. For the TMS-1, users with the same level of experience should be employed in clinical or experimental studies.

Adult↗
PubMed2000

Effect of disagreement between refractive, keratometric, and topographic determination of astigmatic axis on suture removal after penetrating keratoplasty.

BACKGROUND/AIMS: Post-keratoplasty astigmatism can be managed by selective suture removal in the steep axis. Corneal topography, keratometry, and refraction are used to determine the steep axis for suture removal. However, often there is a disagreement between the topographically determined steep axis and sutures to be removed and that determined by keratometry and refraction. The purpose of this study was to evaluate any difference in the effect of suture removal, on visual acuity and astigmatism, in patients where such a disagreement existed. METHODS: 37 cases (from 37 patients) of selective suture removal after penetrating keratoplasty, were included. In the first group "the disagreement group" (n=15) there was disagreement between corneal topography, keratometry, and refraction regarding the axis of astigmatism and sutures to be removed. In the second group "the agreement group" (n=22) there was agreement between corneal topography, keratometry, and refraction in the determination of the astigmatic axis and sutures to be removed. Sutures were removed according to the corneal topography, at least 5 months postoperatively. Vector analysis for change in astigmatism and visual acuity after suture removal was compared between groups. RESULTS: In the disagreement group, the amount of vector corrected change in refractive, keratometric, and topographic astigmatism after suture removal was 3.45 (SD 2.34), 3.57 (1.63), and 2.83 (1. 68) dioptres, respectively. In the agreement group, the amount of vector corrected change in refractive, keratometric, and topographic astigmatism was 5.95 (3.52), 5.37 (3.29), and 4.71 (2.69) dioptres respectively. This difference in the vector corrected change in astigmatism between groups was statistically significant, p values of 0.02, 0.03, and 0.03 respectively. Visual acuity changes were more favourable in the agreement group. Improvement or no change in visual acuity occurred in 90.9% in the agreement group compared with 73.3% of the disagreement group. CONCLUSIONS: Agreement between refraction, keratometry, and topography was associated with greater change in vector corrected astigmatism and was an indicator of good prognosis. Disagreement between refraction, keratometry, and topography was associated with less vector corrected change in astigmatism, a greater probability of decrease in visual acuity, and a relatively poor outcome following suture removal. However, patients in the disagreement group still have a greater chance of improvement than worsening, following suture removal.

Astigmatism↗
PubMed1998

Influence of amount and changes in axis of astigmatism on retinal image quality.

We measured retinal image quality in astigmatic eyes, using the double-pass technique. We analyzed the influence of the amount of astigmatism and changes in axis of astigmatism on the eye's optical performance. Different amounts of astigmatism were obtained by variation of the cylindrical power of a lens situated in front of the eye, between 0.25-diopter (D) overcorrection and 1-D undercorrection at intervals of 0.25 D. Changes in the axis of astigmatism were obtained by rotation of the lens, which neutralizes the astigmatism in an angle of +/- 10 degrees at 5 degrees intervals. The results show the decrease in retinal image quality and the increase in the degree of image astigmatism obtained when the amount of astigmatism increases or the angle between the lens and the eye axis is other than zero. In general, the largest variations correspond to when the astigmatism changes from 0 to 0.25 D or when the axis changes from 0 degree to +/- 5 degrees. The reduction in optical performance is smaller in living eyes than in an eye model or in an artificial eye. The aberrations present in the living eye reduce the relative loss of retinal image quality introduced by astigmatism.

Adult↗
PubMed2006

The changes in corneal astigmatism after botulinum toxin-a injection in patients with blepharospasm.

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 against the- 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↗
PubMedDate not supplied

Enlargement of the temporal clear corneal cataract incision to treat pre-existing astigmatism.

PURPOSE: To evaluate the effect of enlarging the temporal clear corneal cataract incision on pre-existing against-the-rule astigmatism. METHODS: We performed a prospective study of 21 eyes of 21 consecutive patients with astigmatism greater > or = 1.75 D, who underwent temporal clear corneal cataract surgery by phacoemulsification. Patients were divided into two groups. The first group, with medium astigmatism, consisted of 14 patients (14 eyes) with 1.75 to 2.74 D of against-the-rule astigmatism, and had an incision enlarged to 4.5 mm. The second group, with higher astigmatism, consisted of seven patients (seven eyes) with 2.75 to 3.75 D of against-the-rule astigmatism and had an incision enlarged to 5.5 mm. Corneal topography was performed preoperatively and 24 months postoperatively on all eyes. Surgically induced cylinder changes were compared by examining preoperative and postoperative keratometric power using vector analysis. RESULTS: Mean preoperative cylinder in the medium against-the-rule astigmatism group was 2.10 +/- 0.23 D and mean postoperative cylinder at 3 months was 1.17 +/- 0.29 D. Using vector analysis, mean change in cylinder in the medium group was 0.93 +/- 0.42 D (P < .001). In the higher against-the-rule astigmatism group, mean preoperative cylinder was 2.85 +/- 0.10 D and mean postoperative cylinder at 3 months was 1.63 +/- 0.38 D. Mean change in cylinder in the higher astigmatism group was 1.34 +/- 0.58 D (P < .001). For both groups, Student's t-test showed that the postoperative decrease in cylinder was statistically significant (P = .005). CONCLUSION: By enlarging the size of the standard (2.8 to 3.5 mm) temporal clear corneal cataract incision, pre-existing against-the-rule astigmatism was reduced.

Astigmatism↗
PubMed1997

[A corneal topographic analysis of astigmatism after excimer laser photorefractive keratectomy].

OBJECTIVE: To identify the astigmatism changes after excimer laser photorefractive keratectomy (PRK) and the visual influence of astigmatism. METHODS: 109 myopic eyes followed up for more than 1 year were analyzed by using videokeratography, and their visual acuities were examined. Before the operation, the astigmatic errors with cycloplegic refractive examination were -1.00(-)-2.00 D. RESULTS: The position of astigmatism axis was basically consistent with that in corneal topography, but the astigmatism diopter was of some difference between the cycloplegic examination and topographic analysis. With-the-rule astigmatism was in 61% of the eyes, asymmetrical was 33% and against-the-rule was 6% in topographic analysis. Only was a little change in the position of astigmatism axis after PRK observed. Some changes of postoperative astigmatism diopter were seen in different periods. It was increased in the postoperative 10 days or 1 month, and afterwards it became gradually decreased and stable in 6 months to 1 year. The postoperative residual astigmatism was low in degree, that did not affect the visual acuity a great deal. The actual corrected diopter was within the anticipated corrected diopter range of +/- 1.00 D, accounting for 97%. CONCLUSION: By using spherical equivalent method of calculation in PRK, the refractive correction of the operation in cases with myopia and low degree of astigmatism (< -2.00 D) can be satisfactory.

Astigmatism↗
PubMed2000

[Treatment of postoperative astigmatism after perforating keratoplasty using the LASIK method].

The problem of postoperative astigmatism after perforating keratoplasty is complicated. Several possible methods of correction exist. The time and approach to correction of astigmatism after perforating keratoplasty is important. The authors present an account on a group of 10 eyes treated by the LASIK method on an apparatus Keracor 117. In four instances hyperopia with astigmatism was involved and in six eyes myopia with astigmatism, the mean age of the patients being 46.25 years. The mean values of the preoperative spherical hyperopic componenent was +1.37 D and of the myopic spherical component -2.12 D. The preoperative hyperopic astigmatism was +4.5 D and the myopic astigmatism -5.84 D. The follow up period was 9.5 months (1-25 months). The authors evaluate the postoperative natural vision, the resulting postoperative refraction, the incidence of complications and changes of endothelial cells before and after surgery. The resulting mean postoperative hyperopic astigmatism was +0.5 D and the myopic astigmatism -2.4 D. The reduction of values of hyperopic astigmatism was 88.9% and of myopic astigmatism 58.9%, the reduction of the spherical hyperopic component was 100% and of the myopic component 75%. On account of the stabilization of the postoperative refraction, low incidence of peroperative and postoperative complications and the insignificant decrease of endothelial cells the LASIK method is evaluated as effective.

Astigmatism↗
PubMed1998

[Accuracy and predictability of photorefractive keratectomy for astigmatism correction].

OBJECTIVE: To study the accuracy and predictability of photorefractive keratectomy (PKR) for astigmatism correction. METHODS: 53 eyes of 30 cases with compound myopia astigmatism and 33 eyes of 23 cases with simple myopia were treated with PRK and followed up for 6 months. The differences of corneal refractive power provided by corneal topography between the values at postoperative 6 months and that of the preoperative one were calculated with Holladay Ways to get real corrective degree and axis of astigmatism. The results were analyzed and compared with the preoperative predicted values. RESULTS: Six months after PRK, among the compound myopia astigmatism group, the ratio of over correction or under correction of real corrected astigmatic power within +/- 0.50D was 60.4%, the ratio of axis deviation between real and predicted correction within +/- 15 degrees was 58.5%. Among simple myopia group, 48.5% appeared more than -0.50 D myopia astigmatism in real correction, and the cylinder axis position was within 180 degrees +/- 44 degrees. The ratios of uncorrected visual acuity after PRK in the two groups equal to or better than 1.0 were 77.4% and 78.8%, respectively. There was no difference between these two groups (chi(2) = 0.024, P > 0.75). CONCLUSIONS: The method of myopia astigmatism correction using this PRK machine needs to be improved. After PRK treatment, the visual acuity of myopia astigmatism is similar to that of simple myopia group. It shows good efficacy. It is indicated that for myopia astigmatism lower than -2.00D, especially for the astigmatism with the rule, PRK could be performed according to equivalent spherical value.

Adolescent↗
PubMed2001

Postoperative astigmatism after intracapsular cataract surgery: results of a randomised controlled trial in Nepal.

PURPOSE: Postoperative astigmatism following intracapsular cataract extraction with or without anterior chamber intraocular lens implantation is reported as an outcome from a randomised controlled trial. METHODS: Five hundred and two of 1002 eyes randomised to intracapsular cataract extraction with anterior chamber intraocular lens (ICCE/AC IOL) and 417 of 998 eyes to intracapsular cataract extraction with aphakic spectacles (ICCE/AS) were seen for objective refraction one year after surgery. The prevalence and axis of astigmatism were evaluated using univariate analysis. Logistic regression was used to compare the postoperative astigmatism between the groups. RESULTS: Acceptable astigmatism (-0.5 to 0.0 DCyl) in the AC IOL group was found in 60 (12.0%) patients (95% CI 9.1%-14.9%) and in the aphakic spectacles group (AS) in 69 (16.5%) patients (95% CI 12.9%-20.1%), moderate astigmatism (-1.0 to-1.5 DCyl) was found in 153 (30.4%) patients (95% CI 26.4-34.6%) in ACIOL group and in 288 (69.1%) patients (95% CI 64.6%-73.6%) in AS group; and large astigmatism (-2.0 to - 8.0 D Cyl) was found in 289 (57.6%) patients (95% CI 53.1%-61.6%) in ACIOL group and in 60 (14.4%) patients (95% CI 11.0% 17.8%) in AS group. Large astigmatism was approximately four times more common in the ICCE/AC IOL group compared to ICCE/AS group. In both groups, most patients had "against-the-rule" astigmatism, 446 (88.8%) (95%CI 86.0%-91.6%) in AC IOL group and 348 (83.5%) (95%CI 79.9%-87.1%) in AS group. CONCLUSION: Astigmatism is common after intracapsular cataract extraction. Insertion of an anterior chamber IOL increases the risk of astigmatism.

Adolescent↗
PubMed1984

Cycloplegic refractions of infants and young children: the axis of astigmatism.

Review of the cycloplegic refractions of all children who were first examined at Children's Hospital Medical Center in Boston between 1968 and 1978 revealed that 281 children between the ages of 0 and 9.5 years had astigmatism of 1 diopter (D) or greater but no other ophthalmological or neurological problems. In the 85 children under 3.5 years of age, against-the-rule astigmatism was 2.5 times more common than with-the-rule astigmatism, whereas in the 103 children over 5.5 years of age, with-the-rule astigmatism was three times as common as against-the-rule astigmatism. Eleven children who had been astigmatic as infants were recalled; follow-up refraction at ages 5-11 years revealed that all but three had at least a 0.75 D decrease in astigmatism. The remaining three had astigmatism equal in magnitude and axis to the astigmatism they had as infants. Thus, there is a high prevalence of against-the-rule astigmatism in infants and toddlers, which disappears by the time the children reach school age.

Accommodation, Ocular↗
PubMed1984

Photorefractive measurements of astigmatism in infants and young children.

We have photorefracted 312 infants and young children in Tompkins county in New York state and characterized the magnitude and axes of their astigmatisms. The population was solicited by letter from birth announcements or photographed at nursery schools, and was composed of children free of ocular problems. As had been previously reported, we found that the prevalence of astigmatisms of greater than 1 diopter decreased with increasing age. Roughly 7 of 10 infants aged 1 year of younger had one eye with at least 1 diopter of astigmatism or more, while only 1 out of 10 children of age four or more had an eye with 1 or more diopters of astigmatism. A longitudinal study of 26 infants also showed a decrease in the amount of astigmatism over the first three years of life. In infants up to 2 years of age from Tompkins County, the ratio of against-the-rule:oblique:with-the-rule astigmatisms was 15:9:1 in the most astigmatic eye. Generally the axes of oblique astigmatism showed bilateral symmetry. Photorefraction of a group of 159 infants from the city of Seattle showed a similar prevalence of astigmatism, but a slightly different ratio of kinds of astigmatism.

Astigmatism↗
PubMed1994

The comprehensive control of astigmatism during and following intraocular lens implantation.

The operating corneoloscope and Terry operative keratometer were used respectively in 29 and 34 eyes during the intraocular lens implantation to measure the corneal astigmatism qualitatively or quantitatively, so that the tension of incision closure could be adjusted. The surgically induced astigmatism in qualitative group two weeks after the operation was 3.5 +/- 1.70 D and that in quantitative group was 2.56 +/- 1.60 D. There were 55.17% and 38.24% of the eyes with over 2.00 D corneal astigmatism in qualitative and quantitative group two months after the surgery. The astigmatism of both groups at the early stage after the operation was significantly lower than that of the control group (p < 0.05). Argon laser, Nd:YAG laser or razor-blade were used to cut 1 to 3 limbal sutures in 64 eyes with over with-the-rule astigmatism 2.25 D at the early stage (2 months) after the operation. One hour after suture cutting, the with-the-rule corneal astigmatism reduced significantly with an average of 2.61 D. The astigmatism continued to reduce and stabilized one month after the suture cutting. The arcuate keratotomy was performed in 21 eyes, of which the postoperative astigmatism was over 2.25 D (with the average of 3.34 D) more than 6 months after IOL implantation. The mean astigmatism was 0.82 and 1.18 D one day and 6 months after the keratotomy respectively. The uncorrected visual acuity improved significantly after the keratotomy. These results indicate that applying corneoloscope or Terry keratometer to adjust the tension of incision closure during operations, selected suture cutting at the early postoperative stage, and performing arcuate keratotomy at the late postoperative stage be the effective methods to reduce surgically induced corneal astigmatism.

Aged↗