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At least 487 records · Page 27Linked to original sources
PubMed1997

Corneal astigmatism after clear corneal and corneoscleral incisions for cataract surgery.

PURPOSE: To compare the astigmatism induced by clear corneal incisions (CCIs) and corneoscleral tunnel incisions (CSIs) for cataract surgery over 6 months. SETTING: Rotterdam Eye Hospital, rotterdam, The Netherlands. METHODS: Thirty-five patients having phacoemulsification were recruited prospectively; 15 had CCIs and 20, CSIs. Corneal topography was performed by computerized videokeratoscopy preoperatively and 6 months postoperatively. The change in keratometric astigmatism was calculated using the absolute magnitude and vector analysis methods. RESULTS: There was no significant difference between the change in astigmatism produced by the two incisions (Student's t-test). CONCLUSION: The CCI for cataract surgery did not produce significantly greater astigmatism than the CSI. Concern over CCIs having a greater risk of increasing corneal astigmatism is unfounded and does not justify withholding the technique from patients it could benefit.

Astigmatism↗
PubMed1998

Evaluating and reporting astigmatism for individual and aggregate data.

PURPOSE: To demonstrate the proper method for evaluating and reporting astigmatism for individual and aggregate data. SETTING: University of Texas Medical School and Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. METHODS: The surgically induced refractive change (SIRC) was determined for three data sets of patients who have had keratorefractive (photorefractive keratectomy) or cataract surgery. To make changes in refraction comparable, vertex distances for the refractions and keratometric index of refraction were considered. Doubledangle plots and single-angle plots were then used to display the data. Polar values (cylinder and axis) were converted to a Cartesian (x and y) coordinate system to determine the mean value of the induced astigmatism for each data set. RESULTS: Doubled-angle plots clearly demonstrated the trends of induced astigmatism for each data set, and the mean value for induced astigmatism agreed exactly with the intuitive appearance of the plot. CONCLUSIONS: Converting astigmatism data to a Cartesian coordinate system allowed the correct computation of descriptive statistics such as mean values, standard deviations, and correlation coefficients. Using doubled-angle plots to display the data provides the investigator with the best method of recognizing trends in the data.

Astigmatism↗
PubMed1998

Laser in situ keratomileusis for myopia and astigmatism: 6 month results.

PURPOSE: To evaluate the visual and refractive results of laser in situ keratomileusis (LASIK) for mild to moderate myopia with or without astigmatism. SETTING: Barnet-Dulaney Eye Center, Phoenix, Arizona, USA. METHODS: Data were prospectively collected on 124 consecutive eyes having LASIK over 12 weeks. Eyes with a preoperative spherical equivalent (SE) from -1.35 to -10.00 diopters (D) (mean -4.81 D +/- 2.21 [SD]) and cylinder from 0 to 5.00 D (mean 1.12 +/- 1.12 D) were entered in the study. Thirty-one eyes had spherical corrections. Ninety-three eyes had spherocylinder corrections; preoperative astigmatism in these eyes ranged from 0.50 to 5.00 D (mean 1.47 +/- 1.09 D). Surgery included creation of a corneal flap using an automated microkeratome with a 160 microns plate followed by photoablation on the exposed stromal bed. Photoablation was performed using five zones varying from 5.0 to 6.6 mm in eyes with 6.25 D of myopia or less and with five passes at a 5.0 mm zone in eyes with 6.50 D of myopia or more. Astigmatism was corrected using a single-pass ablation through a 6.0 mm slit of varying diameter. RESULTS: Six month follow-up was obtained in 89 eyes (72%). All eyes were completely re-epithelialized by the first postoperative day. Uncorrected visual acuity was 20/40 or better in 81% of eyes at 1 day and in 91% at 6 months. At 6 months, the mean SE was -0.35 +/- 0.77 D; 83% were within +/- 1.00 D of plano. Postoperative astigmatism in the 93 eyes having cylinder correction ranged from 0 to 1.22 D (mean 0.38 +/- 0.42 D). No eye lost more than two lines of best spectacle-corrected visual acuity. Three eyes (2%) required surgical intervention for cap problems. Visually significant corneal haze was not observed. CONCLUSION: In eyes with myopia with or without astigmatism, LASIK provided rapid visual recovery with satisfactory visual and refractive outcomes. The effect of LASIK on visual function (night glare, contrast sensitivity) awaits further study.

Adult↗
PubMed2000

Induced corneal astigmatism using an asymmetric corneoscleral tunnel and a large-optic intraocular lens.

PURPOSE: To prospectively evaluate the induction of corneal astigmatism using an asymmetric corneoscleral tunnel incision (J-incision) to implant large-optic (7.0 mm) intraocular lenses (IOLs). SETTING: Department of Ophthalmology, University of Bonn, Germany. METHODS: Thirty-five patients had sutureless phacoemulsification with implantation of a 7.0 mm poly(methyl methacrylate) posterior chamber IOL using an inverse J-shaped asymmetric tunnel incision. The corneal astigmatism was measured by corneal keratometry and topography preoperatively and 1 day and 1 and 3 months postoperatively. Induced astigmatism was calculated by vector analysis. RESULTS: Mean induced changes in the corneal radii measured by keratometry were 0.17 mm +/- 0.14 (SD) on the first postoperative day, 0.18 +/- 0.14 mm after 1 month, and 0.17 +/- 0.14 mm after 3 months. Mean postoperative induced astigmatism measured by corneal topography was 1.08 +/- 0.66 diopters (D), 0.89 +/- 0.78 D, and 0.85 +/- 0.70 D, respectively. No signs of wound instability were detected. CONCLUSION: An asymmetric corneoscleral incision was suitable for implantation of large-optic IOLs, resulting in immediate stability of the induced cylindrical power in the central 3.0 mm zone as measured by keratometry. A reduction in induced corneal astigmatism can be achieved using this technique versus using symmetrical wound constructions and large-optic IOLs.

Aged↗
PubMed1999

Surgical correction of postkeratoplasty astigmatism with the Hanna arcitome.

PURPOSE: To report the results of arcuate keratotomy performed with the Hanna arcitome in patients with postkeratoplasty astigmatism. SETTING: Department of Ophthalmology, Saint-Antoine Hospital, Paris VI University, Paris, France. METHODS: This retrospective study comprised 22 eyes (22 patients) with postkeratoplasty astigmatism. Paired symmetrical arcuate keratotomy was performed with the Hanna arcitome. Outcome measures included refraction, videokeratography, and keratometry. RESULTS: At 6.6 months +/- 8.9 (SD) after surgery, the mean increase in best spectacle-corrected visual acuity (BSCVA) was 2.1 +/- 2.4 lines. Thirteen eyes gained 2 lines or more of BSCVA, and 15 gained 3 lines or more of uncorrected visual acuity. Two patients had a decrease in BSCVA: 1 had lens opacification unrelated to arcuate keratotomy and 1, increased corneal irregularity. Mean refractive astigmatism was 6.94 +/- 2.11 diopters (D) preoperatively and 3.85 +/- 1.95 D postoperatively (P < .01). Mean change in keratometric astigmatism was -51 +/- 36%. Astigmatism decreased in 21 eyes as measured by manifest refraction, keratometry, and videokeratography; it increased in 1 cornea with a microperforation. CONCLUSIONS: The results of arcuate keratotomy performed with the Hanna arcitome were comparable to those with freehand relaxing incisions. The instrument made safer and more uniform arcuate incisions than a freehand technique.

Adult↗
PubMed2000

"With the rule" astigmatism is not the rule in the elderly. Reykjavik Eye Study: a population based study of refraction and visual acuity in citizens of Reykjavik 50 years and older. Iceland-Japan Co-Working Study Groups.

PURPOSE: To study refractive state and visual acuity in citizens of Reykjavik 50 years and older. METHODS: 1700 persons were randomly selected from the national population census. 1379 could be located and qualified whereof 1045 participated. Evaluation of refraction was performed using Nidek ARK 900 autorefracto-keratometer. Visual acuity was tested on a Snellen chart. RESULTS: The prevalence of hypermetropia increases with age by 0.3 D in five years. The prevalence of "against the rule" astigmatism increased on average 5.3% and oblique 3.9% in five years. Analysis of corneal astigmatism measured by keratometer shows an "against the rule" change with age. CONCLUSIONS: Hypermetropia increases by age. The prevalence of astigmatism increases and the axis turns to "against the rule". The changes in total astigmatism and corneal astigmatism is almost parallel which might indicate that the "against the rule" change is related to changes in the cornea.

Aged↗
PubMed1995

Astigmatism in Bangladeshi and white school entrants in East London: a prospective comparative study.

A prospective comparative study was undertaken to determine the prevalence of significant astigmatism in school entrants living in the same area of East London. Thirty-one Bangladeshi and thirty-one white school entrants were refracted in two local state schools. In the Bangladeshi group, 7 right and 5 left eyes had more than 1 dioptre of astigmatism. Most of this astigmatism was with the rule. In the white group, 1 left eye had more than 1 dioptre of astigmatism. This study has shown a statistically significant incidence of astigmatism in an ethnic group in East London. This difference between two racial groups living in the same area of East London has not previously been documented. In our study, Bangladeshi school entrants may be at greater risk of amblyopia if their refractive error is not identified and corrected.

Astigmatism↗
PubMed1997

Variation in astigmatism following the single-step, self-sealing clear corneal section for phacoemulsification.

PURPOSE: A single-step, self-sealing, 3.2 mm clear corneal section is described and the incidence and variation of surgically induced astigmatism following phacoemulsification over a period of 3 months is determined. METHODS: Twenty-two patients who underwent uncomplicated 3.2 mm clear corneal phacoemulsification with foldable Allergan silicone intraocular lens implantation were autorefracted pre-operatively and on day 1, week 1, week 6 and at 3 months. The variation in induced astigmatism was analysed using the subtraction method and vector analysis. The change in direction of the cylindrical axis was examined. RESULTS: The induced astigmatism represented by the total vector on day 1 was 1.17 D and vector decomposition ratio, ATR:WTR (against-the-rule:with-the-rule), was 21.05:78.95. The total vector increased by 0.5 D in the first week and then stabilised. Vector decomposition showed an against-the-rule astigmatic drift so that by 3 months the ATR:WTR was 40.49:59.91. There was a tendency of the axis of the negative cylinder to swing towards the corneal section meridian on day 1 and to oscillate around that meridian at week 1 and week 6. By 3 months the direction reverted to that pre-operatively, in most cases. CONCLUSIONS: The single-step, self-sealing clear corneal section is mechanically stable and, though there is some variability in the measured astigmatism, there is an acceptable functional result throughout the post-operative period.

Aged↗
PubMed2005

Astigmatism outcomes of scleral tunnel and clear corneal incisions for congenital cataract surgery.

PURPOSE: To evaluate astigmatism outcomes after congenital cataract surgery with intraocular lens implantation using clear corneal or scleral tunnel incisions. METHODS: We retrospectively reviewed the medical records of 46 children (67 eyes), aged 2 months to 12 years, who had undergone nontraumatic cataract extraction and intraocular lens implantation between 1996 and 2001, using a scleral tunnel incision (group 1), or a clear corneal incision (group 2). Refractive astigmatism was measured at 1 week, 3 months, and 5 months after surgery. Paired t-test was used to compare those variables, and Spearman's correlation was used to determine their relation to patient's age. RESULTS: Mean+/-SD astigmatism at 1 week postoperatively was 3.1+/-2.8 Diopter (D) and 2.1+/-1.7 D in groups 1 and 2, respectively. It significantly reduced to 1.1+/-1.2 D and 0.9+/-1.0 D, respectively, in the two groups at 5 months postoperatively (P<0.007). In both groups patients' age was significantly correlated with 1-week postoperative astigmatism (group 1: r=0.64; P=0.001; group 2: r=-0.58; P=0.003), and with the change in cylinder magnitude between 1 week and 3 months postoperatively (group 1: r=-0.67; P=0.001; group 2: r=0.50; P=0.013). CONCLUSION: Children who underwent congenital cataract surgery using clear corneal or scleral tunnel incisions showed high postoperative astigmatism at 1 week postoperatively, which spontaneously reduced during 5 months follow-up. Therefore, suture removal is not necessary in those cases.

Age Factors↗
PubMed2001

[Toric intraocular lens to correct high astigmatism after penetrating keratoplasty in a pseudophakic eye - a case report].

BACKGROUND: After penetrating keratoplasty residual astigmatism can be treated with various options. Correction with spectacles or contact lenses, methods such as radial keratotomy, photorefractive keratectomy (PRK) or Laser-in-situ keratomileusis (LASIK) are limited only to mild and moderate astigmatism. In laser ablation a sufficient corneal thickness must be ensured. On the other hand surgical correction is performed on transplanted tissue which can increase the risk of allograft rejection. In pseudophakic eyes the implantation of an individually designed toric intraocular lens (IOL) according to keratometry and biometry with a cylindrical power up to 12 D provides an alternative method for correcting higher astigmatism. This individually designed IOL can be implanted additionally to the existing IOL. CASE: A 66-year-old patient presented after penetrating keratoplasty and implantation of an IOL 4 years ago with a visual acuity of 20/160 and residual astigmatism of - 10 D x 151(o). After biometry an individually manufactured toric PMMA-IOL of + 12 D cylindrical and - 9.5 D spherical power was implanted via a sclerocorneal tunnel incision additionally to the existing IOL into the ciliary sulcus. Postoperatively a well centered and stable positioned IOL was found. One year after implantation of the toric IOL the position was still unchanged and the graft had remained clear. Spherical equivalent refraction was + 1,5 D - 3,0 D x 141(o), with an uncorrected visual acuity of 20/60. CONCLUSION: Implantation of a toric intraocular lens in pseudophakic eyes allows the correction of high astigmatism after penetrating keratoplasty. The advantage of this method compared to the keratorefractive options lies in its minor manipulation on the allograft.

Aged↗
PubMed2002

[Implantation of an ARTISANtrade mark toric phakic intraocular lens to correct high astigmatism after penetrating keratoplasty].

BACKGROUND: Visual outcome after penetrating keratoplasty is often Iimited by residual astigmatism. Sometimes conservative treatment modalities like glasses or contact lenses fail to correct the keratoplasty-associated astigmatism. Refractive options are arcuate keratotomy, photorefractive keratectomy or laser in situ keratomileusis. The implantation of an ARTISAN toric intraocular lens presents an additive option to correct corneal astigmatism in phakic eyes. This toric intraocular lens (IOL) has an optical zone of 5.0 mm with a sphericaI front and a toric back. The torus of the IOL is available up to 7 D in half dioper steps. CASE REPORT: A 27-year old female presented with a bestcorrected visual acuity of 20/32. Penetrating keratoplasty was performed in 1997 because of a decompensated keratoconus. Despite a clear allgraft visual acuity was limited because of a keratoplasty-related high astigmatism of 7.6 D/124 degrees, which could not be sucessfully treated with glasses or contact lenses. An ARTISAN toric intraocular lens with - 3 D spherical and 7.0 D/0 degrees cylindrical power (individually manufactured) was implanted via a sclerocorneal tunnel incision into the anterior chamber. Postoperatively an optimal graft clarity with a well-centered and stable-positioned IOL was found. After 3 months uncorrected visual acuity was 20/25. Six months after implantation the IOL was still well-centered and uncorrected visual acuity was 20/20. CONCLUSION: Implantation of an ARTISAN toric intraocular lens in phakic eyes is an alternative and new option to correct higher astigmatism. In contrast to the keratorefractive option minor manipulation on the allograft can be expected. For a final conclusion of the endothelial cell loss longer follow-up is necessary.

Adult↗
PubMed2006

[Compensation of corneal astigmatism with toric intraocular lens: results of a multicentre study].

UNLABELLED: This clinical trial was conducted to evaluate visual acuity, refraction and rotation after implantation of the foldable toric intraocular lens (IOL) MicroSil Toric. PATIENTS AND METHODS: 68 eyes of 48 patients from four different surgical departments were examined over a follow-up of three months after cataract surgery. RESULTS: An individually produced IOL with cylindrical correction between 2.0 and 12.0 D was implanted in all eyes. Postoperatively, 68 % of the eyes achieved an uncorrected visual acuity (VA) of 0.5 or better, 12 % achieved 1.0 or better. A corrected VA of 0.5 or better was achieved by 85 %, 31 % achieved a corrected VA of 1.0 or better. Corrected VA improved by 3 (+/- 2) lines. The uncorrected VA improved by 6.0 lines in the mean. The increases in uncorrected and corrected VA were statistically significant (p < 0.001). The efficacy index amounted to 1.1 in the median and 1.3 (+/- 1.5) in the mean. Residual refraction (spherical equivalent) was 0.89 D (+/- 0.7 D) in the mean and was reduced by 5.14 D (+/- 4.78 D) in the mean. The total astigmatic error was reduced both in a statistically as well as in a clinically significant manner from 4.6 D (+/- 2.3 D) to 1.12 D (+/- 0.9 D) in the mean. 75 % of eyes needed a postoperative cylindrical correction of less than 1.5 D, 95 % less than 2.25 D. Corneal astigmatism was not changed significantly (p = 0,435). The surgically induced astigmatism (Naeser) amounted to 0.7 D in the median. In 85 % of the cases IOL rotation was less than 5 degrees. 15 % of the IOLs rotated more than 5 degrees, one IOL more than 10 degrees (max. 28 degrees). Patients ranked their surgical outcome on a scale from 1 (very good) to 6 (poor) which resulted in a mean score of 1.9 (+/- 1.0; min. 1.0; max. 5.0). No clinically relevant correlations of clinical parameters and satisfaction were detected. CONCLUSION: Implantation of the foldable, toric IOL with Z-haptics decreased the refractive error and improved postoperative visual outcome. This IOL was suitable for low as well as for high astigmatism. IOL rotation was low during the follow-up of three months resulting in sufficient correction of the pre-existing astigmatism.

Adolescent↗
PubMed1997

[Modification of axial length and astigmatism by scleral buckling surgery].

BACKGROUND: Scleral buckling surgery for retinal detachment alters the shape of the globe resulting in changes of the refractive state of the eye. MATERIALS AND METHODS: In a prospective study of 52 eyes with retinal detachment we examined changes of corneal astigmatism and axial length induced by encircling buckling or segmental buckling spanning two quadrants. We compared our results with those found in literature. RESULTS: In most patients we found a shortening of the globe, rather in cases with encircling buckles than in the cases with segmental buckles (parallelly to the limbus). We also saw changes in astigmatism postoperatively in all patients. There was no statistically significant difference between patients with encircling and segmental buckles fixed parallelly to the limbus, neither in the change of axial length nor in the change of astigmatism. CONCLUSIONS: In all cases of scleral buckling procedures changes of corneal astigmatism and axial length are to be expected. So our results differ from those of other authors who did not always find a change of astigmatism. We suppose that the authors of the publications which differ from our results did not consider the change of the corneal axis by using the vector method.

Astigmatism↗
PubMed1992

[Correction of astigmatism after penetrating keratoplasty].

Nine patients had a surgical correction of high astigmatism following perforating keratoplasty. In seven of them the reason for the perforating keratoplasty was keratoconus, in two of them Fuchs' endothelial dystrophy. The correction was performed in the seven 31-69 yrs old keratoconus patients 4-19 years (median 10 yrs) after the transplant, in the patients with Fuchs' dystrophy 13 month and 1 year following corneal transplant. In eight cases two circular shaped relaxing incisions of 60 degrees were performed in the steeper meridian, seven times combined with sutures in the opposite meridian. Once a wedge resection was performed. The astigmatism before correcting surgery was 8-19 dpt (median 13 dpt), 3-24 month (median 11 month) 1.75-13 dpt (median 8 dpt). The reduction of astigmatism was 3-10 dpt (median 8 dpt). In 5 of 9 patients the astigmatism could be corrected by spectacles, in two more patients no spectacles were prescribed because of cataract. After this series of astigmatic correction we think that incisions without sutures are superior. This method could replace rekeratoplsty in the future.

Adult↗
PubMed1991

[Astigmatism in cataract surgery. Retrospective study of 1,304 cases].

We performed a retrospective computerized study of 1304 consecutive cataract extractions, of which 251 were intracapsular and 1053 extracapsular. The analysis of surgically induced astigmatism after a mean follow-up of 22.8 months involved 639 cases. Operations were performed by two experienced surgeons using a similar and standardized technique; however the location of the incision varied without selecting patients: 391 were corneal, 248 limbal. We found that corneal incision gives significantly more against-the-rule astigmatism (average -0.61 dptr) than limbal incision (average -0.32 dptr). The suture induced astigmatism has no determining effect on the final astigmatism (correlation coefficient = 0.011). Selective suture cutting is an interesting technique for an individual dosage of the amount of final astigmatism.

Astigmatism↗
PubMed1983

[Refraction in the 1st year of life and the development of astigmatism].

Retinoscopy was performed in 205 children under atropine cycloplegia during the first year of life. In 22% an astigmatism (minimum 1.0 D) was found with a small peak of incidence between the 31st and 40th week. In a follow-up study (45 children) the incidence and degree of astigmatism were found to increase slightly. During the first 3 years of life esotropic children developed an astigmatic anisometropia (minimum 1.0 D difference in the astigmatism of the two eyes) more frequently the non-esotropic children. The hypothesis that astigmatic anisometropia is produced by visual deprivation in esotropic individuals is discussed.

Astigmatism↗
PubMed1991

Relaxing incisions for postkeratoplasty astigmatism.

We report 100 cases of postkeratoplasty astigmatism, ranging from 4 to 20.5 diopters, treated with the following procedures: relaxing incisions, relaxing incisions with augmentation sutures, and repeated relaxing incisions with augmentation sutures according to the degree of astigmatism. Patients were divided into three study groups (group 1 for preoperative defects ranging from 4 to 10 diopters, group 2, from 10.5 to 15 diopters, and group 3 for defects exceeding 15 diopters). Mean preoperative astigmatism was 7.15 +/- 1.67, 12.56 +/- 1.37, and 17.50 +/- 1.51 diopters in each group, respectively. The net decrease in astigmatism after surgery was 5.53 +/- 1.44, 9.68 +/- 1.80, and 14.87 +/- 1.69 diopters in each group, respectively. Postoperatively, spectacle-corrected visual acuity improved by two Snellen lines in the group 1, five in the group 2, and nine in the group 3. The mean time to achieve stable results after surgery was 2.2 +/- 0.3, 2.7 +/- 0.4, and 4.2 +/- 0.7 months in each group, respectively (two patients in group 2 and all patients in group 3 underwent a two-step procedure). The relaxing incisions procedure, eventually modified by either adding compression sutures or repeating the incisions after 8-10 weeks, offers the possibility of a wide range of corrections for postkeratoplasty astigmatism with acceptable postoperative periods for visual rehabilitation.

Adolescent↗
PubMed2001

Experimental study using pig eyes for realizing ideal astigmatic keratotomy.

PURPOSE: The effects of varying the incision length and depth were analyzed using pig eyes to acquire information for realizing an ideal method of astigmatic keratotomy (AK). METHODS: Single and paired arcuate incisions were made on pig corneas using a diamond knife. Incisions with varying lengths of 40 degrees, 60 degrees, and 90 degrees were made with the incision depth fixed at 90% of corneal thickness. Next, paired incisions with varying incision depth from 20% to 95% of corneal thickness were made with the incision length fixed at 90 degrees. The changes in corneal shape were analyzed using corneal topography and the degrees of astigmatic change were measured using a surgical keratometer. RESULTS: For short single and paired incisions (40 degrees or 60 degrees in length), narrow areas of flattenings occurred, and steepenings were observed on both sides adjacent to the flattened areas. For long paired incisions of 90 degrees length, wide areas of flattenings and steepenings were observed with an approximately 1:1 coupling ratio, and a positive linear relationship between the incision depth and degree of astigmatic change was observed in the range of incision depth between 40% and 80% of corneal thickness. CONCLUSION: This experimental study suggests that for achieving ideal corneal sphericity after AK, long incisions covering the entire steep areas (paired 90 degrees incisions for regular astigmatism) should be used and the degree of astigmatic correction may be controlled by varying the incision depth.

Animals↗