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PubMed1992

Induced astigmatism following small incision cataract surgery combined with trabeculectomy.

The combination of phacoemulsification and implantation of foldable intraocular lenses through a small incision with a trabeculectomy is increasingly preferred in glaucoma patients with coexisting cataract. Small incisions induce less astigmatism and thereby enhance visual recovery. This study should clarify if this benefit of small incision cataract surgery is preserved when combined with a trabeculectomy. Thirty-five eyes were included in this study. Preoperative astigmatism measurements were compared with those obtained one month and one year postoperatively. Vector analysis was performed. A series of 30 cases which underwent small incision cataract surgery alone were used as a control group. One month postoperatively the eyes undergoing the combined procedure showed about the same with-the-rule astigmatic peak (mean: +0.32 dpt.) as the control group eyes (mean: +0.26 dpt.; p > 0.05). One year postoperatively both groups showed the same against-the-rule astigmatic shift (mean: -0.28 dpt.; p > 0.05). In conclusion, patients undergoing small incision cataract surgery combined with trabeculectomy showed a small amount of surgically induced astigmatism. When compared with patients which underwent small incision cataract surgery alone, the difference in astigmatic changes was found to be statistically not significant.

Astigmatism↗
PubMed1994

Relaxing incisions with compression sutures for control of astigmatism after penetrating keratoplasty.

BACKGROUND: Ten per cent of patients with persisting postoperative astigmatism following penetrating keratoplasty (PK) require surgical re-intervention, despite an otherwise "successful" transplant. Relaxing incisions (RIs) in combination with compression sutures seem to be the preferable procedure. However, poor predictability and lack of long-term experience complicate the issue. Here we report the 2-year follow-up results of 25 patients with high PK astigmatism treated by means of RIs and compression sutures. METHODS: Commonly, free-handed RIs were placed at the graft-host interface and 10-0 nylon compression sutures were placed perpendicular to the incisions. PK sutures had been removed no less than 4 months prior to refractive surgery. RESULTS: Nineteen eyes regained a functional vision of > or = 0.4. The net decrease in astigmatism was 6.1 +/- 4.3 D (47 +/- 21%). The mean vector-corrected change in astigmatism was 13.1 +/- 5.7 D. Cylinder axis variation was reasonably low, with a correlation of attempted versus achieved axis of r = 0.85. Within the first 3 months after operation the induced astigmatism regressed by, on average, 5.5 +/- 4.3 D, making intraoperative overcorrection necessary. As an inevitable side effect, refractive procedures resulted in a myopic shift (4.7 +/- 6.9 D) in spherical equivalence. CONCLUSION: RIs and compression sutures are very useful in reducing postkeratoplasty astigmatism if correction of extremely high cylinder (> 10 D) is not intended. However, predictability still remains unsatisfactory and more than one operation may be required.

Adult↗
PubMed2004

Correction of pre-existing astigmatism during cataract surgery: comparison between the effects of opposite clear corneal incisions and a single clear corneal incision.

BACKGROUND: Opposite clear corneal incisions (OCCIs) have been reported to reduce pre-existing astigmatism (PEA) during cataract surgery. Our goal was to evaluate the effect of OCCIs on correcting PEA in cataract surgery. METHODS: Non-randomized prospective study. Thirty-four patients with PEA of greater than 1.5 diopters (D) underwent clear cornea phacoemulsification cataract extraction with 3.2-mm OCCIs (OCCI group). The control group consisted of 23 successive patients with PEA <1.5 D who underwent cataract extraction without OCCI. Best-corrected visual acuity, keratometry and refraction were recorded for all patients pre-operatively and post-operatively. RESULTS: Using keratometric findings, mean astigmatism correction was 1.3 D (+/-0.9 SD; decreased from 2.6 D pre-operatively to 1.4 D post-operatively) in the OCCI group but only 0.4 D in the control group (P<0.005), 8 months post-operatively. Vector analysis of astigmatism correction showed greater change for OCCI patients (1.8 D vs 1.0 D, P=0.002). Using the Holladay method for calculating surgically induced refractive change (SIRC), the OCCI group showed a higher value of SIRC (-1.6 D vs -0.97 D), but this was not statistically significant. The OCCI patients showed a greater and significant change in refraction spherical equivalent than the controls. No complications related to OCCI or cataract surgery occurred during the follow-up period. CONCLUSIONS: Opposite clear cornea incision seems to be a simple, predictable, safe and effective procedure in reducing pre-existing corneal astigmatism in cataract surgery. It has an enhanced effect in correcting astigmatism compared to a single clear cornea incision when using keratometric findings value but not when using refractive data. Future studies are needed to document the long-term effect of OCCI and to evaluate the correlation between incisions of different size and astigmatism correction.

Aged↗
PubMed1985

Photokeratometric and photorefractive measurements of astigmatism in infants and young children.

We have measured corneal and total astigmatism on 161 eyes of 90 normal infants and young children aged 2 months to 5 years using the techniques of photorefraction and photokeratometry. Both the mean corneal and mean total astigmatism were found to decrease with increasing age. We found large and significant correlations between corneal and total astigmatism in the 0-1, 1-2 and 2-3 year-old infants and children. Previous studies have shown that photorefractive measurements of astigmatism compare well with retinoscopic measurements of the same infants. As part of this study we measured the corneal astigmatism of 19 adults (38 eyes) by photokeratometry and with a clinical keratometer and found that the two measures were well correlated (r = 0.820). We conclude that the major component of total astigmatism seen in uncyclopleged infants of ages 0-3 years is corneal in nature.

Adult↗
PubMed2005

Laser in situ keratomileusis for primary and secondary mixed astigmatism.

PURPOSE: To evaluate and compare the efficacy, predictability, and safety of LASIK in the correction of primary and secondary mixed astigmatism after previous LASIK surgery. DESIGN: Retrospective, comparative case series. METHODS: The retrospective study included 118 eyes having LASIK with the LADARVison 4000 excimer laser (Alcon Surgical, Orlando, Florida) to correct mixed astigmatism. The eyes were divided into two groups: in group A (n = 64), LASIK was for primary mixed astigmatism and in group B (n = 54), LASIK was for secondary mixed astigmatism. Mean follow-up was 10.6 +/- 5.90 months. RESULTS: Overall, the postoperative UCVA was 20/20 in 51% of eyes and 20/40 or better in 97% of eyes at the last visit. The mean refractive cylinder was -2.18 +/- 0.94 D preoperatively and -0.56 +/- 0.56 D postoperatively. Sixty-one percent of eyes had a refractive cylinder of 0.50 D or less. One eye lost 2 lines of BSCVA (0.8%). None of the eyes had postoperative BSCVA worse than 20/25. The difference of preoperative cylinder was significant between group A and group B (P = .000). However, there was no statistical difference of postoperative refraction and UCVA between these two groups. At 12 months, the mean vector magnitude achieved was 93% of intended cylinder correction with a mean angle of error of -3.0 +/- 16 degrees. CONCLUSIONS: LASIK is a safe, effective, and predictable procedure to treat both primary and secondary mixed astigmatism. Nomogram adjustment with spherical and astigmatism components individually may improve refractive outcomes.

Adult↗
PubMed2003

Shortterm and longterm visual and astigmatic results of an opposing 10-0 nylon double running suture technique for penetrating keratoplasty.

BACKGROUND: In ophthalmic surgery, corneal transplantation (penetrating keratoplasty) may be employed when the clarity of the cornea has been significantly compromised by conditions such as scarring, edema, and variable corneal thickness. Irregularities in corneal curvature can occur postoperatively. This astigmatism is of concern, because it can impair visual acuity despite an otherwise good surgical result. Different suturing techniques have been developed to minimize astigmatism. The purpose of this study was to evaluate an opposing 10-0 nylon double running suture technique for penetrating keratoplasty. STUDY DESIGN: A retrospective study was undertaken of 91 records of patients who underwent penetrating keratoplasty performed by one surgeon (RNG). This represents 54.8% of 166 consecutive cases. Every eye with an opposing double running suture and a 1- to 3-month postsuture removal followup was selected and evaluated for best corrected visual acuity and astigmatism, excluding eyes that developed graft failure or corneal ulcer or that had lack of adequate followup. The cases were divided into five groups by preoperative diagnosis: pseudophakic bullous keratopathy (n = 43), aphakic bullous keratopathy (n = 5), keratoconus (n = 17), Fuchs dystrophy (n = 12), and miscellaneous (n = 14). The mean standard followup period was 13.7 months after penetrating keratoplasty. Thirty percent of the eyes had an extensive followup, with a mean of 33 months after penetrating keratoplasty. RESULTS: Eighty-two percent of the patients had a significant improvement of their visual acuity postoperatively, defined by a five-line improvement of best corrected visual acuity or a best corrected visual acuity of 20/40 or better. The mean astigmatic keratometric reading was 3.98 diopters, with a manifest refraction cylinder of 3.42 diopters at the 1- to 3-month postsuture removal visit. This study also shows that there is no statistically significant change in keratometric astigmatism or manifest refraction cylinder from the 1- to 3-month postsuture removal measurements to the more extensive followup of 18 to 66 months after penetrating keratoplasty (p > 0.10). CONCLUSIONS: This suture technique allows for excellent longterm stability of the wound with visual and astigmatic results that are comparable to those of previous studies. The use of the opposing double running suture is a viable alternative to some of the other widely used techniques and may be considered more stable and secure.

Adult↗
PubMed2006

Corneal astigmatism correction with opposite clear corneal incisions or single clear corneal incision: comparative analysis.

PURPOSE: To compare the astigmatic correcting effect of paired opposite clear corneal incisions (OCCIs) on the steep axis with that of single clear corneal incisions (CCIs) in cataract patients having phacoemulsification. SETTING: Rajendra Prasad Centre for Ophthalmic Sciences, AIIMS, New Delhi, India. METHODS: This randomized prospective clinical study comprised 40 eyes of 40 patients with topographic astigmatism of more than 1.50 diopters (D). Paired 3.2 mm OCCIs were made in the steep axis in Group 1 and single CCIs in Group 2. Preoperative evaluation included uncorrected visual acuity, refraction, applanation tonometry, dilated fundoscopy, biomicroscopic examination, keratometry, and topography. The steep axis was marked before sub-Tenon's anesthesia was given and routine phacoemulsification was performed through a 3.2 mm CCI on the steep axis. An additional opposite 3-step self-sealing CCI was made in Group 1. Patients were examined 1, 4, and 12 weeks postoperatively. Visual acuity, refraction, keratometry, and topography were evaluated. RESULTS: The mean preoperative and postoperative topographic corneal astigmatism was 2.51 D +/- 0.92 (SD) and 0.91 +/- 0.54 D, respectively, in Group 1 and 2.16 +/- 0.80 D and 1.57 +/- 0.70 D, respectively, in Group 2. Mean astigmatic correction was 1.66 +/- 0.5 D and 0.85 +/- 0.75 D in Group 1 and Group 2, respectively. Mean surgically induced astigmatism, measured by a vector-corrected method, was 1.66 +/- 0.50 D and 0.85 +/- 0.75 D in Group 1 and Group 2, respectively (P = .00). The coupling ratio was -0.96 in Group 1 and -0.87 in Group 2. The spherical equivalent was +0.23 +/- 0.41 D in Group 1 and +0.11 +/- 0.17 D in Group 2 at 12 weeks. Uncorrected visual acuity was better in Group 1 than in Group 2 (P = .032). There was no difference in best corrected visual acuity between the groups. There were no incision-related complications. CONCLUSION: Paired OCCIs were predictable and effective in providing an enhanced effect for correcting preexisting corneal astigmatism in cataract surgery.

Astigmatism↗
PubMed2006

Amblyopia in astigmatic children: patterns of deficits.

Neural changes that result from disruption of normal visual experience during development are termed amblyopia. To characterize visual deficits specific to astigmatism-related amblyopia, we compared best-corrected visual performance in 330 astigmatic and 475 non-astigmatic kindergarten through 6th grade children. Astigmatism was associated with deficits in letter, grating and vernier acuity, high and middle spatial frequency contrast sensitivity, and stereoacuity. Although grating acuity, vernier acuity, and contrast sensitivity were reduced across stimulus orientation, astigmats demonstrated orientation-dependent deficits (meridional amblyopia) only for grating acuity. Astigmatic children are at risk for deficits across a range of visual functions.

Amblyopia↗
PubMed2000

Photorefractive keratectomy for compound myopic astigmatism.

PURPOSE: To evaluate the safety and efficacy of photorefractive keratectomy for the treatment of primary compound myopic astigmatism. METHODS: In a prospective study, 93 eyes from 56 patients with a mean spherical equivalent of -4.98 +/- 1.80 diopters (range, -1.75 to -8.5) underwent photoastigmatic refractive keratectomy with the Summit Apex Plus excimer laser using erodible mask technology and were followed for 2 years. Primary outcome measures included an assessment of astigmatic correction through vector analysis, manifest refraction, uncorrected visual acuity, corneal clarity, and the presence of adverse symptoms. RESULTS: Eighty-five eyes (91.4%) were available for analysis at 6 months. Mean spherical equivalent refraction was reduced 85% (mean, -0.75 +/- 0.85 diopter) and the target-induced astigmatism was reduced 70% (mean, 0.98 +/- 1.88 diopters). Forty-eight eyes (56%) had an uncorrected visual acuity of 20/20 or greater, whereas 70 eyes (82%) had an uncorrected visual acuity of 20/40 or greater. Twenty-four eyes (26% ) required re-treatment because of undercorrection of the spherical equivalent and astigmatic components after the 6-month follow-up. Fifty-nine of the remaining eyes were available at the 24-month visit. Mean spherical equivalent refraction was reduced to -0.39 +/- 0.72 diopter (91.8%). The target-induced astigmatism was reduced 64% from 1.74 diopters. Forty-one eyes (81.3%) were within +/-1.0 diopter of attempted spherical equivalent correction. Stability within a spherical equivalent of +/-0.5 diopter occurred after the first postoperative month. Fifty-six eyes (94.9%) had an uncorrected visual acuity of 20/40 or greater, whereas 34 eyes (57.6 %) demonstrated an uncorrected visual acuity of 20/20 or greater. One eye (1.7%) lost 2 or more lines of best spectacle-corrected visual acuity. CONCLUSION: Photoastigmatic refractive keratectomy with the Summit Apex Plus excimer laser is a safe and effective method of reducing compound myopic astigmatism. However, higher re-treatment rates may result from significant undercorrections because of current laser algorithms and variability in the mean angle of error.

Adult↗
PubMed2002

Against-the-rule (ATR) astigmatism as a predicting factor for the outcome of amblyopia treatment.

PURPOSE: To evaluate whether with-the-rule (WTR) or against-the-rule (ATR) astigmatism influences the treatment outcome of anisometropic amblyopia. DESIGN: A cohort study. METHODS: Retrospective study of patients with unilateral amblyopia due to anisometropia without strabismus. Ninety-eight patients with simple, compound, mixed, oblique myopic, and hyperopic astigmatism were divided into seven groups based on the type of astigmatism. The groups were reviewed as to the amount of anisometropia, duration of occlusion, and best-corrected visual acuity (BCVA) before and after treatment. RESULTS: There was statistically significant longer duration of occlusion and less lines gain of BCVA among patients with hyperopic ATR astigmatism compared with patients with hyperopic WTR astigmatism (P =.0143 and P =.0000, respectively) and myopic ATR patients compared with myopic WTR patients (P =.0392 and P =.0192, respectively). For the same parameters, group differences were also statistically significant when all hyperopic or myopic simple/compound/mixed ATR patients were compared with all hyperopic or myopic simple/compound/mixed WTR patients (P =.0015 and P =.0000, respectively). CONCLUSION: The outcome of amblyopia treatment seems to be less favorable in patients with either hyperopic or myopic ATR astigmatism. Near vision impairment may be more amblyogenic than distance vision impairment during visual development.

Amblyopia↗
PubMed2000

Astigmatism and the development of myopia in children.

While it is now established that astigmatism is more prevalent in infants and young children than in the adult population, little is known about the functional significance of this astigmatism, especially its role, if any, in emmetropization and the development of myopia. Manifest refractions (mean of 16 per subject) were obtained from 245 subjects starting in the first year, with 6-23 years of regular follow-up. Results showed that infantile astigmatism is associated with increased astigmatism and myopia during the school years. Two possible mechanisms underlying this association are discussed: (1) infantile astigmatism disrupts focusing mechanisms; and (2) ocular growth induces astigmatism and myopia.

Adolescent↗
PubMed2001

Corneal interactive programmed topographic ablation customized photorefractive keratectomy for correction of postkeratoplasty astigmatism.

OBJECTIVE: This study evaluated the efficacy, predictability, stability, and safety of a software program (Corneal Interactive Programmed Topographic Ablation [CIPTA], LIGI, Taranto, Italy), which, by transferring programmed ablation from the corneal topograph to a flying-spot excimer laser, provides customized laser ablation for correction of postkeratoplasty astigmatism. DESIGN: Noncomparative consecutive interventional case series. PARTICIPANTS: Ten eyes of 10 patients with a mean age of 41.4 years (range, 26-64) had CIPTA-guided photoastigmatic refractive keratectomy (PARK) at the Clinica Oculistica of Bari (Italy). Two patients were treated for hyperopic astigmatism and eight for myopic astigmatism. All the patients had irregular astigmatism after penetrating keratoplasty. OPERATION: Topography was acquired by a corneal topograph (Orbscan II, Orbtek, Inc., Salt Lake City, UT). This, together with refractive data, was processed to obtain a customized altimetric ablation profile that was transferred to a flying-spot laser (Laserscan 2000, Lasersight, Orlando, FL). MAIN OUTCOME MEASURES: Data on uncorrected (UCVA) and best-corrected (BCVA) visual acuity, predictability, stability of refraction, and any complications were analyzed. RESULTS: Mean follow-up was 8.4 months (range, 6-12; SD 2.4). At the last postoperative examination, seven eyes (70%) had a UCVA superior to 20/40. Three eyes (30%) had a UCVA of 20/20. Five eyes (50%) were within 0.50 diopters (D) of attempted correction in the spherical equivalent, and eight eyes (80%) within 1 D. Index of success of astigmatic correction was 0.19. All the eyes (100%) gained Snellen lines of BCVA. We did not observe any decentration and/or haze after PARK treatment performed in this study. CONCLUSIONS: The combination of topographic data with computer-controlled flying-spot excimer laser ablation is a suitable solution for correcting irregular astigmatism after penetrating keratoplasty.

Adult↗
PubMed1998

Excimer laser treatment of myopic astigmatism. A comparison of three ablation programs.

OBJECTIVE: The purpose of the study was to evaluate the precision, accuracy, and safety of three different modes of excimer laser surgery for myopic astigmatism. DESIGN: A prospective interventional case series. PARTICIPANTS: A total of 150 eyes with compound myopic astigmatism were treated. INTERVENTION: Ablation programs included the VISX Twenty/Twenty excimer laser using either the sequential mode (58 eyes) or the elliptical mode (54 eyes) and the Technolas-Chiron Keracor 116 hybrid scanning laser (38 eyes). MAIN OUTCOME MEASURES: Reduction in cylinder and sphere, vector analysis (polar values), uncorrected visual acuity, and best spectacle-corrected visual acuity were evaluated at 1, 6, and 12 months. RESULTS: By 12 months, sphere was reduced by 95.1%, 87.7%, and 75% in low-astigmatism eyes treated with the VISX sequential, VISX elliptical, and Technolas modes, respectively, and by 92.2%, 98%, and 77.6% in high-astigmatism eyes. By 12 months, cylinder was reduced by 51.5%, 72.2%, and 36.3% in low-astigmatism eyes and by 70%, 78%, and 45.6%, respectively, in high-astigmatism eyes. Vector analysis showed that the elliptical treatment produced more significant reductions in mean polar values than the other two treatments at various timepoints. CONCLUSION: These results suggest that the ablation approach may influence the clinical result.

Adult↗
PubMed1998

Different suturing techniques variously affect the regularity of postkeratoplasty astigmatism.

OBJECTIVE: This study aimed to determine the effect of various suturing techniques on the regularity of postkeratoplasty astigmatism. DESIGN: A prospective clinical trial. PARTICIPANTS: Sixty-two consecutive patients undergoing penetrating keratoplasty by the same surgeon (MB) participated. INTERVENTION: Each patient was assigned to one of four groups according to the suturing technique used (a = 16 interrupted 10-0 nylon sutures; b = 2 running 10-0 nylon sutures, each with 8 bites; c = 2 running 10-0 nylon sutures, each with 12 bites; d = 2 running 10-0 nylon sutures, each with 16 bites). This was the only parameter permitted to be changed in the standard keratoplasty procedure used for all cases. Corneal topography was performed 1, 3, and 6 months after surgery. The astigmatic patterns seen on the corneal maps then were classified into regular (symmetric or asymmetric bowtie patterns) or irregular (distorted bowtie, multiaxial, or other patterns). MAIN OUTCOME MEASURES: Regularity of postkeratoplasty corneal astigmatism was measured. RESULTS: At all postoperative examination times, the percentage of irregular astigmatic patterns was highest in group a and lowest in group d (chi-square test: P < 0.005). Groups b and c showed intermediate values. The entity of the astigmatic error as measured by the simulated K-readings of the topographic maps did not differ significantly in the four groups. CONCLUSIONS: A suturing technique using 2 running sutures with 16 bites each can minimize irregular postkeratoplasty astigmatism as long as sutures are in place, when compared with interrupted sutures or double-running sutures of less than 16 bites.

Adolescent↗
PubMed2000

Selective zonal ablations with excimer laser for correction of irregular astigmatism induced by refractive surgery.

OBJECTIVE: To demonstrate the safety and efficacy of selective zonal ablations with excimer laser for the correction of irregular astigmatism induced by refractive surgery. DESIGN: Thirty-one eyes of 26 patients. Retrospective and noncomparative case series. METHODS: The authors reviewed the medical results of the two series of consecutive cases of irregular astigmatism induced by refractive surgery. One group showed a topography map with a defined pattern: decentered ablation, decentered steep central island, central irregularity, and peripheral irregularity. The other group showed an irregular astigmatism without defined pattern. Selective zonal ablation was performed with a broad-beam excimer laser. Laser ablations were adjusted according to the Munnerlyn formula. A phototherapeutic keratectomy (PTK) mode was used in all cases without using viscous masking solution. MAIN OUTCOME MEASURES: Uncorrected visual acuity, best spectacle-corrected visual acuity (BCVA), and Holladay diagnostic summary (Eye Sys 2.000) were considered before and after surgery to obtain the qualitative and quantitative characteristics of the visual acuity and corneal topography. The corneal uniformity index (CUI) was used to evaluate the corneal surface changes induced by the selective zonal ablations in the correction of irregular astigmatism. It proved to be a useful tool in the understanding of astigmatic changes when it is not possible to apply the vector analysis. RESULTS: In group 1, the irregular astigmatism was significantly improved in 96.4% of cases. The CUI was improved from 58+/-0.3% to 87+/-0.8%, P < 0.005 (Student's t-test). The improvement of the BCVA was from 20/40+/-20/100 to 20/25+/-20/100, P < 0.005 (Student's t-test). The results obtained in group 2 were not clinically significant in terms of improvement of CUI and BCVA. CONCLUSIONS: Using the corneal topographic map as a guide, selective zonal ablations with excimer laser can be used to create a more regular corneal surface, when a defined pattern of topographic irregularities can be defined.

Adult↗
PubMed2000

Astigmatism correction with a foldable toric intraocular lens in cataract patients.

PURPOSE: To determine the efficacy and rotational stability of a toric posterior chamber silicone intraocular lens (IOL) to correct preoperative astigmatism in cataract patients. SETTING: Department of Ophthalmology, University Hospital of Vienna, Vienna Austria. METHODS: Between 1993 and 1998, foldable toric single-piece plate-haptic silicone IOLs were implanted in 37 eyes (30 patients). The cylindrical IOL power was 2.00 diopters (D) (n = 29), 3.50 D (n = 7), or 4.00 D (n = 1). Phacoemulsification was performed through a scleral or a corneal sutureless self-sealing incision. Outcomes of Snellen visual acuity (without, with spherical, and with best correction), refractive and keratometric astigmatism, and IOL rotation after early postoperative (mean 15.9 days +/- 10.1 [SD]) and long-term (mean 20.3 +/- 16.6 months) follow-ups were evaluated. RESULTS: At last follow-up, 31 eyes (83.8%) had a spherically corrected and 34 (91.9%) a best corrected visual acuity of 0.5 (20/40) or better. Mean preoperative refractive and keratometric astigmatism was 2.68 and 2.70 D, respectively. At the last postoperative follow-up, mean refractive astigmatism was reduced to 0.84 D; keratometric astigmatism was 2.30 D. In 7 eyes (18.9%), the IOL axis was rotated a maximum of 25 degrees. In all 37 eyes, the axis of the toric IOL remained within 30 degrees of rotation. CONCLUSIONS: Early postoperative and long-term follow-ups showed effective and stable correction of astigmatism after implantation of a foldable toric posterior chamber silicone IOL.

Aged↗
PubMed2000

Theoretical analysis of ablation depths and profiles in laser in situ keratomileusis for compound hyperopic and mixed astigmatism.

PURPOSE: To compare the theoretical ablation depths and profiles of 4 treatment strategies for compound hyperopic and mixed astigmatism. SETTING: Theoretical analysis. METHODS: Corneal contour drawings of theoretical corneal ablation profiles during laser in situ keratomileusis (LASIK) and photoastigmatic refractive keratectomy were made. The depths of tissue ablation in 4 treatment strategies for compound hyperopic astigmatism (Groups 1 to 4) and for mixed astigmatism (Groups 5 to 8) were compared: (1) combined hyperopic spherical and myopic cylindrical treatments (Groups 1 and 5); (2) combined spherical and hyperopic cylindrical treatments (Groups 2 and 6); (3) combined cylindrical treatments (Groups 3 and 7); (4) combined cross-cylinder and spherical equivalent treatments (Groups 4 and 8). RESULTS: In compound hyperopic astigmatism, the 4 approaches resulted in identical final curvatures, but the ablation depths were greatest in Group 1 (combined hyperopic spherical and myopic cylindrical treatments). The smallest amount of ablation occurred in Group 2 (combined hyperopic spherical and hyperopic cylindrical treatments) and Group 3 (combined hyperopic cylindrical treatments), which had similar tissue ablation patterns. In mixed astigmatism, the greatest ablation depth was in Group 5, followed by Group 8, and Groups 6 and 7. The tissue ablation depths and profiles were similar in Groups 6 and 7. CONCLUSION: The treatment approaches in Groups 2, 3, 6, and 7 (which avoided the use of minus cylinder) resulted in the smallest degree of stromal ablation. Patients with compound hyperopic or mixed astigmatism may benefit from reduced ablation depths by deferring treatment until hyperopic cylindrical and/or combined cylindrical treatments are available.

Astigmatism↗
PubMed2001

Limbal relaxing incisions in congenital astigmatism: 6 month follow-up.

PURPOSE: To evaluate the effectiveness of limbal relaxing incisions (LRIs) for correcting naturally occurring astigmatism. SETTING: Ankara Hospital, Ankara, Turkey. METHODS: This prospective analysis of the results of the first LRIs in 22 eyes of 13 patients with congenital astigmatism was done using a modified Gills nomogram and was based on preoperative refractive astigmatism determined by manifest and cycloplegic refractions. There were no adjustments based on sex or age. RESULTS: An absolute decrease of 0.91 diopter (D) (44%) in mean astigmatism was achieved after 6 months in 22 eyes. The mean uncorrected visual acuity (logMAR) increased from 0.42 to 0.26 from preoperatively to 6 months postoperatively. No patient lost best corrected visual acuity. Most regression occurred in eyes with more than 3.50 D of astigmatism and between the first and third postoperative months. CONCLUSION: Limbal relaxing incisions are a practical, simple, and forgiving approach for the correction of lower degrees of astigmatism.

Adolescent↗