With-the-rule Astigmatism Research Articles

Prevalence of Astigmatism in 6- to 72-Month-Old African American and Hispanic Children: The Multi-Ethnic Pediatric Eye Disease Study

To determine the age-, gender-, and ethnicity-specific prevalence of astigmatism in African American and Hispanic children aged 6 to 72 months. Population-based, cross-sectional study. The Multi-Ethnic Pediatric Eye Disease Study is a population-based evaluation of the prevalence of vision disorders in children ages 6 to 72 months in Los Angeles County, California. Seventy-seven percent of eligible children completed a comprehensive eye examination. This report provides the results from 2994 African American and 3030 Hispanic children. Eligible children in 44 census tracts were identified during an in-home interview and scheduled for a comprehensive eye examination and in-clinic interview. Cycloplegic autorefraction was used to determine refractive error. The proportion of children with astigmatism defined as cylindrical refractive error ≥ 1.50 diopters (D) in the worse eye. The astigmatism type was defined as with-the-rule (WTR) (+ cylinder axis 90 ± 15 degrees) and against-the-rule (ATR) (+ cylinder axis 180 ± 15 degrees); all other orientations were considered oblique (OBL). The prevalence of astigmatism and its types were also determined for worse eye cylindrical refractive error ≥ 3.00 D. Prevalence of astigmatism ≥ 1.50 D was higher in Hispanic children compared with African American children (16.8% vs. 12.7%, respectively; P<0.0001). Hispanic children also showed a higher prevalence of astigmatism ≥ 3.00 D than African American children (2.9% vs. 1.0% respectively; P<0.0001). The prevalence of astigmatism ≥ 1.50 D showed a significant decreasing trend with age (P<0.0001). The prevalence of WTR, ATR, and OBL astigmatism ≥ 1.50 D was 13.9%, 0.6%, and 2.2%, respectively, in Hispanic children, and 7.8%, 2.2%, and 2.7%, respectively, in African American children. We observed ethnicity-related differences in astigmatism prevalence in preschool children. The age-related decrease in astigmatism prevalence in preschool children likely reflects emmetropization.

Onset and Progression of With-the-Rule Astigmatism in Children with Infantile Nystagmus Syndrome

The purpose of this study was to examine the onset and progression of with-the-rule (WTR) astigmatism during the first 8 years of life in children with idiopathic infantile nystagmus syndrome (INS) or INS associated with albinism and to compare their development with that of normal children. Also explored was whether early WTR astigmatism influences emmetropization in children with INS and whether there is evidence of meridional emmetropization. Cycloplegic refractions culled from medical records were converted into power vector components: M (spherical equivalent), J(0) (positive J(0) indicates WTR astigmatism), and J(45) (oblique astigmatism). Two diagnostic groups (idiopathic, n = 106; albinism, n = 95) were evaluated and compared with a reference normal group (n = 495). Four age subgroups were evaluated: age< or =0.5 year, 0.5<age< or =1 year, 1<age< or =4 year, and 4<age< or =8 year; in the normal group, no data were available for 4- to 8-year-olds. In addition, two longitudinal groups of children with INS (idiopathic, n = 22; albinism, n = 27) were studied. WTR astigmatism was prevalent among children with INS, even during infancy. Both the prevalence and magnitude of WTR astigmatism increased with age in both INS groups. Predicted J(0) from the fitted longitudinal data agreed with cross-sectional data. Moreover, the spherical equivalent of children with INS demonstrated little emmetropization during the first 8 years of life. Both the cross-sectional and longitudinal data showed that WTR astigmatism was common among children with INS and increased in magnitude with age during the first 8 years of life. Changes observed in meridional refractive error with age were consistent with meridional emmetropization in children with INS and WTR astigmatism.

120: Progression of with-the-rule astigmatism in children with infantile nystagmus syndrome

Introduction: Our previous cross-sectional study showed a high prevalence of with-the-rule (WTR) astigmatism in infants and children with infantile nystagmus syndrome (INS). This study investigated the longitudinal development of WTR astigmatism in children with idiopathic INS and INS associated with albinism.

Astigmatism after superonasal and superotemporal clear corneal incisions in phacoemulsification

To determine the astigmatism outcomes after cataract surgery performed using superonasal and superotemporal clear corneal incisions. Department of Ophthalmology, Kartal Training and Research Hospital, Istanbul, Turkey. This prospective study includes consecutive 45 eyes of 34 patients having phacoemulsification with implantation of foldable acrylic intraocular lens through a corneal tunnel incision between January and April 2004. The right eye always had a superotemporal incision while the left eye a superonasal incision. Astigmatism was measured by keratometry readings before surgery and 3rd, 15th, and 45th days postoperatively. The surgically induced astigmatism (SIA) was calculated by the vector analysis using the Holladay-Cravy-Koch method at 3rd day, 2nd and 6th weeks postoperatively. The mean preoperative astigmatism was 0.74 +/- 0.45 diopter (D) in the temporal incision group and 0.69 +/- 0.39 D in the nasal incision group. Fifty-eight percent of eyes had against-the-rule (ATR) astigmatism, 26% had with-the-rule (WTR) astigmatism, and 16% were astigmatically neutral. At 6 weeks, 46% of eyes had ATR astigmatism and 35% had WTR astigmatism. The mean total astigmatism was lower in the temporal incision group than in the nasal incision group at all successive examinations postoperatively. Although the total astigmatism decreased at 6 weeks in both groups, temporal incisions yielded less total and surgically induced astigmatism (P < .05). Cataract surgery using superotemporal incision induced significantly less SIA in the early postoperative period.

Iris recognize-guided LASIK with Zyoptix System for correction of myopic astigmatism

To assess the safety, efficacy, predictability, stability, and changes in cylindrical degree and axis after iris recognize-guided LASIK with the Zyoptix 4.01 System for the correction of myopic astigmatism. The present study was a prospective, nonrandomized, self-controlled trial. Iris recognize-guided LASIK with the Zyoptix 4.01 System (Bausch & Lomb) was performed in 97 patients (183 eyes) with myopic astigmatism in a 6-month trial. Patients were divided into 3 group according to the pre-operative cylindrical degree: Group 1, -0.50 to -1.00D, 79 eyes; Group 2, -1.25 to -2.00D, 70 eyes; Group 3, 2.00 to 4.00D, 34 eyes. They were also grouped by preoperative astigmatism axis: Group A, with the rule (WTR) astigmatism, 126 eyes; Group B, against the rule (ATR), 34 eyes; Group C, oblique axis astigmatism, 23 eyes. After a Hansatome microkeratome cut, iris recognized wavefront-based excimer ablation (Zyoptix 100) was performed. The degree and axis of astigmatism pre-operative and at various times post-operatively (1 day, 1 month, 3 month and 6 months) were analyzed and compared. At 6 month post-operatively, uncorrected visual acuity (VA) was 1.0 or better in 92.3% of the eyes, and 0.5 or better in all eyes. No eye lost > or = 1 lines of best spectacle-corrected VA (BSCVA) at 6 month post-operatively; 60 eyes gained 1 line of BSCVA, and 22 eyes gained 2 lines. The cylindrical degree of astigmatism decreased from (-1.54 +/- 0.65) D of pre-operation to (-0.26 +/- 0.25) D (6 month, post-operatively), the difference between these two groups was statistically significant. The uncorrected VA (UCVA) and the degree of astigmatism returned to normal in the first week and tended to be stable after 1 month. Six months after the operation, WTR astigmatism decreased from106 eyes (per-operation) to 45 eyes (post-operation). ATR astigmatism decreased from 43 eyes (per-operation) to 31 eyes (post-operation). Oblique astigmatism increased from 34 to 38 eyes. Sixty-nine eyes became non-astigmatism 6 months after the operation. Iris recognize-guided LASIK using Zyoptix is an effective and safe procedure for the treatment of myopic astigmatism.

Changes in astigmatism in children with congenital nystagmus

Astigmatism is commonly reported in children with and without nystagmus. In children less than 4 years of age the astigmatism changes from against the rule (ATR) to with the rule (WTR) astigmatism in children without nystagmus. However, little is known about children with congenital nystagmus. We compared astigmatism in children with congenital nystagmus below 4 years and above 4 years of age. Three hundred and fifty-six eyes in 178 children who satisfied the study criteria were included. The children were divided into those below 4 years of age (n of eyes = 192) and those above (n of eyes = 164). Cycloplegic refraction (with manual retinoscopy) carried out at presentation and at the last follow-up were recorded and compared. Cycloplegia was achieved using cyclopentolate eye drops. Outcome of eyes with no astigmatism at initial presentation was compared with the final refraction in both the age groups. The visual acuity at the first presentation was compared with the visual acuity at the last presentation. Average follow-up duration was 3.36+/-1.59 years. On presentation, 176 (49.44%) eyes did not have any astigmatism. We found that 26 (25.2%) out of the 103 children below 4 years of age who did not have any astigmatism on presentation developed WTR astigmatism after a mean follow-up of 3.5+/-1.5 years. (p= 0.042). In children >or=4 years of age only 7 (9.6%) children out of 73 developed WTR after a mean follow-up of 3.4+/-1.4 years. The visual acuity change was not found to be significant in the two groups. The majority (90.3%) improved or had same visual acuity in group A and 88.9% improved or had the same visual acuity in group B at the last follow-up (p= 0.77). Our incidence of WTR astigmatism in children with congenital nystagmus is similar to those previously reported series. Our data suggest that there is a significant chance that children under 4 years with congenital nystagmus may develop WTR astigmatism compared with children above 4 years of age. With the rule (WTR) astigmatism is common in children with nystagmus. Children under 4 years of age presenting with no astigmatism may acquire WTR astigmatism as they grow. The amount of astigmatism increases with age in children with nystagmus. Visual acuity, however, remains stable as the age advances.

Corneal Topography in Involutional Ectropion of the Lower Eyelid

The shape and position of the eyelids affect corneal topography. This study evaluated preoperative and postoperative corneal topography in involutional ectropion of the lower eyelid. Eighteen patients with unilateral involutional lower eyelid ectropion underwent ophthalmic examinations and corneal topography before surgical correction and at the 6-month postoperative interval. Corneal topographies were evaluated with the Holladay Diagnostic Summary package. The fellow eyes served as controls. Parameters evaluated included the regularity of astigmatism (RA), steep refractive power (SRP), flat refractive power (FRP), and total astigmatism (TA). Preoperatively, RA was found significantly decreased in the eyes with ectropion compared with the fellow eyes, whereas differences in other parameters were statistically nonsignificant. Postoperatively, RA was significantly increased, whereas SRP was significantly reduced. The percentage of eyes with with-the-rule astigmatism (WTRA) was increased postoperatively, although astigmatic axis changes were not systematic. Postoperative topographic changes may be related to either restoration of symmetry in the upper and lower lid apposition on the cornea or to rearrangement of the tear film. Further research will be required to assess whether corneal topographic findings could be used as an index of the severity of eyelid laxity and to evaluate the effects of topographic changes on corneal and total optical aberrations.

Prevalence of Refractive Errors in a Rural South Indian Population

To report the prevalence of refractive errors in a rural south Indian population. Four thousand eight hundred subjects (age, >39 years) from rural south India were enumerated for a population-based study. All participants underwent complete ophthalmic evaluation. Subjects who were phakic in the right eye with best corrected visual acuity of 20/40 or better were included for analysis. Association of refractive errors with age, sex, cataract, and diabetes mellitus were analyzed. Of the 3924 responders, 2508 were eligible. The unadjusted prevalence of emmetropia (spherical equivalent [SE], -0.50 to +0.50 diopter sphere [DS]), myopia (SE < -0.50 DS), high myopia (SE < -5.00 DS), and hyperopia (SE > 0.50 DS) were 50.60%, 26.99%, 3.71%, and 18.70% and age and gender adjusted for the rural Tamil Nadu population were 46.77%, 30.97%, 4.32%, and 17.94%, respectively. The prevalence of emmetropia decreased significantly with age (P < 0.0001), and the prevalence of myopia and high myopia increased significantly with age (P < 0.001) and were significantly associated with nuclear sclerosis (P < 0.001). The prevalence of hyperopia increased until 60 years of age and then decreased. Hyperopia was more common among women than men (P < 0.001) and was negatively associated with nuclear sclerosis (P < 0.001) and positively with diabetes mellitus (P = 0.008). Of the participants with astigmatism (cylindrical error greater than 0.50 DC), 9.80% had with-the-rule (WTR) and 77.44% against-the-rule (ATR) astigmatism. The prevalence of WTR and ATR astigmatism significantly decreased (P < 0.001) and increased (P = 0.006) with age, respectively. The pattern of refractive errors in this rural south Indian population is similar to those reported in other tropical regions of the world.

Corneal and lenticular components of total astigmatism in a preschool sample.

To examine the contribution of corneal and lenticular components to total astigmatism in preschool low and high astigmats to determine whether there was any compensation for high astigmatism by the lenticular component. Cycloplegic refractive and keratometric measures using the Retinomax K-Plus (Nikon Inc., Melville, NY) were conducted on 129 children (mean age, 51.1 +/- 8.4 mo) in Oxford County, Canada. We divided the sample into high astigmats (total cylinder > or =1 D; mean, 1.38 +/- 0.43 D; n = 29) and normal astigmats (total cylinder < or =0.75 D; mean, 0.22 +/- 0.20 D; n = 100). Measures of total and corneal cylinder were transposed into J0 and J45 components, where positive and negative J0 values quantified with-the-rule (WTR) and against-the-rule astigmatisms, respectively, and J45 quantified oblique astigmatism. WTR astigmatism was dominant in both the high and normal astigmatic group. J0 and J45 components of corneal astigmatism were highly correlated with total astigmatism in high astigmats, whereas only J0 was significantly correlated with total astigmatism in normal astigmats. Although the magnitude of total and corneal cylinder was significantly greater in high astigmats, overall lenticular cylinder was similar in both groups. However, the Fourier transforms showed high astigmats to have significantly lower lenticular J0 and higher lenticular J45 than the normal astigmats. Astigmatism in 3- to 5-year-old children is primarily corneal. In preschool children, the lens does not vary in response to high amounts of corneal WTR astigmatism, and in fact, it increases the oblique astigmatism component when the corneal component is high. In high astigmats, lenticular astigmatism contributes to both J0 and J45 components, whereas the corneal contribution is primarily J0.

Prevalence of refractive error in Bangladeshi adults: Results of the National Blindness and Low Vision Survey of Bangladesh

Purpose To determine the prevalence of refractive errors and to investigate factors associated with refractive error in adults 30 years of age and older in Bangladesh. Design Cross-sectional study. Participants A nationally representative sample of 12 782 adults 30 years of age and older. Methods The sample of subjects was selected based on multistage, cluster random sampling with probability-proportional-to-size procedures. The examination protocol consisted of an interview that included measures of literacy, education, occupation, and refractive correction. Visual acuity testing (logarithm of the minimum angle of resolution [logMAR]), automated refraction, and optic disc examination were performed for all subjects. Subjects with <6/12 (0.3 logMAR) acuity in either eye were graded additionally for cataract and underwent a dilated fundal examination. Subjects for whom no refractive error was recorded (312 subjects; 2.7%) or who had undergone cataract surgery (123 subjects; 1.1%) were excluded from the analysis. Main outcome measures Refractive error and socioeconomic variables (literacy, education, occupation). Results Eleven thousand six hundred twenty-four subjects were examined (90.9% response rate; mean age±standard deviation, 44±12.6 years). Five thousand four hundred eighty-nine subjects (49.1%) were men and 5700 subjects (50.9%) were women. Mean spherical equivalent was −0.19 diopters (D; ±1.50 D). Six thousand four hundred twelve subjects (57.3%) were emmetropic, 2469 (22.1%) were myopic (<−0.5 D), and 2308 (20.6%) were hypermetropic (>+0.5 D). Two hundred six subjects (1.8%) were highly myopic (<−5 D). Myopia was more common in men (26.3%) than in women (21.0%), whereas hyperopia was more common in women (27.4%) than in men (15.8%). Overall, myopia increased with age (17.5% of those aged 30–39 years were myopic, compared with 65.5% of those age 70 years and older). A subanalysis of subjects without cataract showed increasing hyperopia with age and an association between myopia and higher education. Myopia was more common among the employed than in unemployed subjects. Astigmatism (>0.5 D), present in 3625 subjects (32.4%), was more common among women, illiterate subjects, and unschooled subjects. Against-the-rule astigmatism was more common (58.7%) than oblique astigmatism (29.3%), which was more common than with-the-rule (WTR) astigmatism (12.1%). Against-the-rule astigmatism and oblique astigmatism increased with age, unlike WTR astigmatism. Of 830 (7.5%) subjects, women were more commonly anisometropic (>1.0 D). Anisometropia increased with age. Conclusions Refractive error data are described for a country and region that previously have lacked population-based data. Prevalence and factors associated with refractive error are presented, with a detailed comparison with other population-based surveys regionally and internationally.

Astigmatism outcomes of horizontal temporal versus nasal clear corneal incision cataract surgery

Purpose: To compare the short- and long-term astigmatism outcomes after cataract surgery using temporal clear horizontal corneal incisions and nasal horizontal clear corneal incisions. Setting: Wilmer Eye Institute, Johns Hopkins Hospital, Baltimore, Maryland, USA. Methods: This retrospective study included a consecutive series of eyes having phacoemulsification with implantation of a 6.0 mm foldable acrylic intraocular lens through a 3.5 mm horizontal clear corneal incision at 180 degrees (temporal incision in right eyes, nasal incision in left eyes). Astigmatism was measured by keratometry readings before surgery and 6 weeks and 12 months postoperatively. Results: The mean preoperative astigmatism in the 178 eyes (94 right, 84 left) of 161 patients was 0.78 diopter (D); 54.5% of eyes had against-the-rule (ATR) astigmatism, 22.5% had with-the-rule (WTR) astigmatism, and 14.0% were astigmatically neutral. A significant shift toward WTR astigmatism occurred postoperatively. At 6 weeks, 48.3% of eyes had WTR astigmatism and 23.0% had ATR astigmatism. At 12 months, 43.8% had WTR astigmatism and 25.8% had ATR astigmatism. Vector analysis revealed a mean surgically induced astigmatism (SIA) of 1.17 D at 6 weeks and 1.04 D at 12 months. The side of the incision significantly affected SIA. At 6 weeks, temporal incisions yielded a mean SIA of 0.74 D and the nasal incisions, of 1.65 D. This trend in SIA persisted at 12 months: 0.71 D for temporal incisions and 1.41 D for nasal incisions. Conclusions: Cataract surgery using a horizontal clear corneal incision induced WTR astigmatism 6 weeks and 12 months postoperatively. Temporal incisions induced significantly less astigmatism than nasal incisions.

Astigmatic axis is related to the level of spherical ametropia.

Against-the-rule (ATR) astigmatism has been shown to be a risk factor for subsequent myopia development. In this study, we evaluated the relationship between astigmatic axis and the level of spherical ametropia in both myopes and hypermetropes. Astigmatic axes were analyzed in two distinct cohorts. First, 53 high myopes from families that were recruited for linkage analysis were compared with an age-matched control group derived from family members. Second, cross-sectional data were analyzed for 90,884 subjects attending 19 optometric practices in the north of England. Initially, the relationship between astigmatic axis and cylinder power and between axis and sphere power were analyzed in 21- to 40-year olds and 21- to 30-year olds, respectively, to control for the effects of age. Multivariate logistic regression analysis was then performed using data for all compound astigmats in the cohort to examine the effect of sphere power, cylinder power, age, and sex on the odds of subjects having either ATR or with-the-rule (WTR) astigmatism. In the genetic study cohort, there was an excess of WTR astigmats in the high myopes compared with controls, but this only reached significance for the right eye. In the much larger optometric practice sample, the association of WTR astigmatism with high myopia was highly significant. A parallel increase in WTR astigmatism was also found for high hypermetropes. In addition, the odds of having WTR astigmatism were increased if subjects were young or had a high cylinder power. ATR astigmatism occurred more often with increasing age and in subjects with lower spherical ametropia. Indeed, for 21- to 30-year-old subjects with low myopia (> or =-2.00 DS in the least minus meridian), ATR occurred more often than WTR astigmatism. Astigmatic axis was found to be related to the level of ametropia, with both a higher spherical component or higher cylinder power increasing the odds of astigmatism being WTR. Low ametropes, particularly myopes, were more likely to have axes ATR.

Peripheral corneal relaxing incisions combined with cataract surgery

Purpose To analyze the effectiveness of peripheral corneal relaxing incisions (PCRIs) in correcting corneal astigmatism during cataract surgery. Setting Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. Methods In 115 eyes of 94 patients (mean age 69 years ± 12 [SD]), cataract surgery was combined with PCRIs. The PCRIs were created according to a nomogram based on age and preoperative keratometric astigmatism. Postoperative keratometric astigmatism was measured at 1 day and 1 and 4 months. Vector analyses using the Holladay-Cravy-Koch formula and Alpins method were performed. Results The PCRIs significantly decreased keratometric astigmatism in patients with preexisting with-the rule (WTR) or against-the-rule (ATR) astigmatism and increased the percentage of the eyes with lower keratometric astigmatism in each group. Four months postoperatively in patients with WTR astigmatism, single and paired 6.0 mm PCRIs induced mean with-the-wound minus against-the-wound changes (WTW–ATW) of −0.55 diopter (D) and −1.18 D, respectively. In eyes with ATR astigmatism, the mean WTW–ATW changes induced by single 4.5 mm, single 6.0 mm, and paired 6.0 mm PCRIs were −2.18 D, −2.02 D, and −2.72 D, respectively. These mean WTW–ATW changes did not significantly regress from 1 day to 4 months postoperatively. Conclusions Peripheral corneal relaxing incisions were effective in reducing preexisting astigmatism during cataract surgery. A modified nomogram is proposed. The long-term effect of PCRIs should be evaluated.

Astigmatic changes after excimer laser refractive surgery

Purpose To compare the astigmatic changes induced by spherical and elliptical excimer laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). Setting University-based refractive surgery practice. Methods Three-month refractive data from 317 eyes of consecutive patients having spherical PRK, astigmatic PRK (A-PRK), spherical LASIK, and astigmatic LASIK (A-LASIK) by a single surgeon (J.S.P.) using VISX 2020B and Star lasers over 2 years were studied for astigmatic changes resulting from the surgical procedure. Results At 3 months, the mean change in absolute astigmatism was +0.15 diopter (D) and −0.07 D in the spherical PRK and LASIK groups, respectively. Photorefractive keratectomy tended to induce with-the-rule (WTR) astigmatism, while LASIK was astigmatically neutral. As expected, the eyes treated with A-PRK and A-LASIK achieved a greater reduction in absolute astigmatism (−1.02 D and −1.28 D, respectively) than those treated with spherical PRK and LASIK. The qualitative nature of the astigmatic change was different between flap-based and PRK-based procedures. Conclusions Spherical PRK is more likely than spherical LASIK to induce astigmatism, with a tendency toward WTR astigmatism. The eyes treated with spherical LASIK had no preponderant change in the direction of astigmatic magnitude or axis. Astigmatic PRK and LASIK effectively reduced astigmatism along the preoperative axis; A-LASIK tended to induce a random resultant axis in most patients.

Induced astigmatismafter photorefractive keratectomy

Purpose: To retrospectively analyze a group of patients to determine whether their induced astigmatism was caused by asymmetry in the laser beam, asymmetry in ablation rates, or wound healing in different corneal meridians. Setting: Single-center physician office. Methods: In this study, 146 eyes of 116 patients who had photorefractivakeratectomy(PRK) for myopia with the Apex laser (Summit Technology) were retrospectively identified. In 28 eyes, the patient's chair had been rotated 90 degrees from its usual position under the laser. The vector-summated mean change in astigmatism in eyes with the chair rotated 90 degrees was compared with that in a group of control eyes in which the chair was in the usual position. Results: The vector-summated mean change in the control eyes was 0.30 diopter (D)at 83 degrees. Forty-eight of 113 eyes (42.5%) had induced with-the-rule (WTR) astigmatism, and 14 of 113 eyes (12.4%) had induced against-the-rule (ATR) astigmatism. In the eyes in which the chair was rotated 90 degrees, vector-summated mean change was 0.10 D at 13 degrees ( P < .0005). One of 27 eyes (3.7%) had induced WTR astigmatism, and 13 of 27 eyes (48.1%) had induced ATR astigmatism ( P < .001, chi-square). Conclusion: Astigmatism induced by myopic PRK with the Apex laser was small. The axis of induced astigmatism rotated 90 degrees when the patient's chair was rotated, implying that it is inhomogeneities in the beam rather than meridional asymmetry in ablation rates or wound healing that are responsible for induced astigmatism.[]

Relationship between preoperative axis of astigmatism and postoperative astigmatic change after superior scleral incision phacoemulsification

Purpose: To evaluate the effect of the preoperative axis of astigmatism on the outcome of corneal astigmatism after sutured 5.2 to 5.7 mm superior incision phacoemulsification.Setting: Departments of Ophthalmology, Odense and Vejle Hospitals, Denmark.Methods: Seventy-three consecutive patients with preoperative corneal astigmatism of 2.0 diopters (D) or less, axial length between 20.0 and 25.5 mm, and no eye disease except cataract were grouped according to preoperative with-the-rule (WTR) or against-the-rule (ATR) astigmatism. The keratometric cylinder, induced keratometric cylinder (subtraction), and induced cylinder (Jaffe) were measured and calculated 10 to 12 months postoperatively.Results: The postoperative keratometric cylinder and induced keratometric cylinder were significantly higher in the ATR group (P < .00001; mean difference [95% confidence limits]: 0.76 D [0.54; 0.98] and 0.69 D [0.46; 0.92], respectively). There was no significant difference between groups in induced cylinder (Jaffe).Conclusion: The estimated differences were significantly in favor of patients with preoperative WTR astigmatism. The findings support using a temporal incision in cases with a preoperative ATR axis of astigmatism.

Comparison of surgically induced astigmatism after sutureless temporal clear corneal and scleral frown incisions

Purpose: To compare the corneal astigmatic changes induced by clear corneal incisions with those induced by scleral tunnel frown incisions, both from a temporal approach, in sutureless cataract surgery.Setting: Department of Ophthalmology, College of Medicine, National Cheng Kung University, Tainan, Taiwan, Republic of China.Methods: This prospective study comprised 120 eyes divided into two groups of 60 each based on incision type. All patients had examinations with an autokeratometer preoperatively and 1 week and 1, 3, and 6 months postoperatively.Results: Simple subtraction of the scalar analysis in each group showed minimal astigmatic changes; however, the standard deviation of astigmatic change was greater in the clear corneal incision group. The mean vector analysis of surgically induced astigmatism in the scleral frown incision group was 0.69, 0.75, 0.72, and 0.61 diopter (D) at 1 week and 1, 3, and 6 months, respectively. In the clear corneal incision group, it was 1.55, 1.12, 0.93, and 0.92 D at the same intervals. In the scleral frown incision group, Naeser's polar value also showed minimal changes in polar astigmatism throughout the study; in the clear corneal incision group, it showed a mean with-the-rule (WTR) astigmatic shift of +0.73, +0.22, +0.13, and +0.08 D at 1 week and 1, 3, and 6 months, respectively.Conclusion: Corneal stability was achieved with minimal astigmatic change 1 week after scleral frown incisions, while clear corneal incisions induced greater WTR astigmatism with delayed stabilization 1 to 3 months postoperatively.