Limbal relaxing incisions for primary mixed astigmatism and mixed astigmatism after cataract surgery

PURPOSE: To evaluate the effect of limbal relaxing incisions (LRIs) in the treatment of primary mixed astigmatism and mixed astigmatism after cataract surgery. SETTING: Department of Ophthalmology, In?nü University, Malatya, Turkey. METHODS: Limbal relaxing incisions were performed to correct astigmatism in 37 eyes of 26 patients with mixed astigmatism. Twenty-four eyes had primary astigmatism, and 13 eyes had astigmatism after cataract surgery. The length, number, and depth of the incisions were determined using the Gills and Gayton nomogram. The manifest refractive astigmatism was measured preoperatively and 1 day, 1 week, and 1, 3, 6, and 12 months postoperatively. Surgically induced astigmatism using the vector method, preoperative and postoperative uncorrected visual acuity (UCVA), and best spectacle-corrected visual acuity (BSCVA) were evaluated. Follow-up was at least 6 months in all cases. RESULTS: The mean preoperative and postoperative refractive astigmatism was 3.31 diopters (D) +/- 1.50 (SD) and 1.59 +/- 1.28 D, respectively (P <.001). The mean absolute change in refractive astigmatism was 1.72 +/- 0.81 D. No patient lost lines of UCVA or BSCVA. The safety index was 1.21 and the efficacy index, 0.88. The mean preoperative and postoperative UCVA was 0.29 +/- 0.22 and 0.54 +/- 0.31, respectively (P =.0001) and the mean BSCVA, 0.61 +/- 0.30 and 0.74 +/- 0.30, respectively (P =.0001). The mean vectorial magnitude was 2.32 +/- 1.36 D at the last follow-up. There were no serious postoperative complications. CONCLUSION: Limbal relaxing incisions are a simple, safe, and effective method to correct primary mixed astigmatism and mixed astigmatism after cataract surgery.     

Limbal relaxing incisions to correct astigmatism in clear corneal cataract surgery.

PURPOSE: To prevent surgically induced astigmatism following clear corneal cataract surgery. METHODS: Limbal relaxing incisions of 6- or 8-mm length and 0.55-microm depth were performed in 52 patients (52 eyes) with a spherical cornea (20 eyes) or mean with-the-rule astigmatism (32 eyes) of 0.80 +/- 0.30 D after temporal corneal cataract incision. A control group (47 eyes; 19 spherical and 28 with-the-rule astigmatism) underwent the same surgical procedure without limbal relaxing incisions. RESULTS: Six months after surgery, mean with-the-wound change using the Holladay analysis was -0.08 +/- 0.50 D in spherical eyes with limbal relaxing incisions and +0.50 +/- 0.70 D in control eyes. Patients with preoperative with-the-rule astigmatism showed a mean with-the-wound change of -0.09 +/- 0.50 D after limbal relaxing incisions; in corresponding control eyes, mean change was +0.39 +/- 0.70 D. CONCLUSION: Limbal relaxing incisions are a reliable and safe procedure to reduce postoperative astigmatism.     

Effect of temporal and nasal unsutured limbal tunnel incisions on induced astigmatism after phacoemulsification

PURPOSE: To compare the surgically induced corneal astigmatism after unsutured temporal and nasal unsutured limbal tunnel incisions. SETTING: Departments of Ophthalmology, Marienhospital, Aachen, and Johann Wolfgang Goethe-University, Frankfurt am Main, Germany. METHODS: In a prospective clinical study, 42 eyes of 21 patients with a mean age of 75.1 years had phacoemulsification and implantation of a foldable hydrophobic acrylic intraocular lens using a 3.6 to 3.8 mm unsutured limbal tunnel incision. The right eye always received a temporal incision and the left eye, a nasal incision. Computerized videokeratography was performed preoperatively and 2 weeks and 6 months postoperatively. Surgically induced astigmatism was calculated by vector analysis using the Holladay-Cravy-Koch formula. The 2 groups were compared using a paired Wilcoxon test. RESULTS: The mean surgically induced corneal astigmatism in the temporal incision group was 0.62 diopters (D) +/- 0.48 (SD) 2 weeks postoperatively and 0.47 +/- 0.32 D at 6 months and in the nasal incision group, 1.55 +/- 0.84 D and 1.05 +/- 0.57 D, respectively. The difference between the groups was statistically significant (P <.05). CONCLUSIONS: There was a highly statistically significant difference in surgically induced corneal astigmatism after temporal and nasal unsutured limbal tunnel incisions. The degree of induced astigmatism and the difference between the temporal and the nasal incisions decreased over time. A nasal tunnel incision is not appropriate for astigmatism-neutral surgery.     

Limbal relaxing incisions (LRI) for correcting astigmatism in clear corneal cataract surgery

BACKGROUND: To prevent surgically induced astigmatism following clear corneal cataract surgery. PATIENTS AND METHODS: Limbal relaxing incisions of 6 or 8 mm length respectively and 0.5 mm depth were performed in 52 patients with spheric cornea or astigmatism with the rule of 0.8 +/- 0.3 dpt after temporal corneal cataract incision. The same amount of patients, operated on with the same surgical procedure except keratotomies, served as control. RESULTS: After 6 months the with-the-wound-change (WTW) in the LRI axis using the Hollady method was -0.08 +/- 0.5 dpt in the spheric cases with limbal keratotomy and +0.5 +/- 0.7 dpt in the control cases. The patients with preoperative astigmatism with the rule showed a WTW in the LRI axis of -0.09 +/- 0.5 dpt in the keratotomy cases and +0.39 +/- 0.7 dpt in the corresponding control patients. CONCLUSION: Limbal relaxing incision is a reliable and safe procedure to reduce postoperative astigmatism after cataract surgery.     

Minimizing induction of astigmatism in preoperative spherical cornea a. by mini-incision surgery with foldable IOL and b. by corneal tunnel incision with limbal relaxing incision]

BACKGROUND: In case of a spheric cornea preoperatively the refractive effect of a clear corneal cataract incision is undesirable. We studied two actual techniques to minimize the surgically induced astigmatism. PATIENTS AND METHODS: Temporal clear corneal incision was performed in 77 patients with practically spherical cornea (0.2 +/- 0.1 D). 27 patients with 4.1-mm clear corneal stretch incision and 5 mm PMMA lens implantation served as control. 25 further patients were operated on with the same technique, but 2 additional limbal relaxing incisions (LRI) of 0.55-mm depth and 8 mm length at 6 and 12 o'clock were performed. In 25 patients a foldable acrylic lens (Acrysof) was implanted through a 3.2-mm temporal clear corneal incision. Corneal topography results were evaluated in all patients by the Jaffe and the Holladay analysis. RESULTS: The surgically induced astigmatism of 0.8 +/- 0.5 dpt in the control group was reduced to 0.4 +/- 0.3 dpt by LRI and by reduction of the incision size as well in the treatment groups. With-the-wound-change (WTW) in the Holladay analysis was 0.6 +/- 0.7 dpt in the control group and around 0 in the groups with astigmatism reducing techniques. CONCLUSION: To preserve a spherical cornea in clear corneal-tunnel incision, compensating limbal relaxing incisions (LRI) or ultra-small incisions with foldable lens implantation should be performed.     

Effect of pterygium surgery on corneal topography

PURPOSE: To evaluate the effect of successful pterygium surgery on corneal topography. METHODS: Computerized corneal topography was performed on 20 eyes with pterygium before and 3 months after successful excision and limbo-conjunctival autograft surgery. Corneal shape, corneal spherical power, simulated keratometric astigmatism, surface regularity index (SRI), and surface asymmetry index (SAI) were assessed before and after surgery. Pre- and postoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and manifest refraction spherical equivalent (MRSE) were also evaluated. RESULTS: Changes in corneal shape were mainly a decrease in midline corneal flattening. Corneal spherical power was 41.65+/-3.29 diopters (D) (mean +/- SD) preoperatively and 44.58+/-1.55 D postoperatively (p=0.04). Simulated keratometric astigmatism was 5.47+/-3.45 D preoperatively and 1.79+/-1.52 D postoperatively (p=0.0005). SRI was 1.39+/-0.93 preoperatively and 1.10+/-0.57 postoperatively (p=0.03). SAI was 1.17+/-1.09 preoperatively and 0.75+/-0.73 postoperatively (p=0.02). UCVA was 0.31+/-0.33 preoperatively and 0.52+/-0.32 postoperatively (p=0.04). BSCVA was 0.73+/-0.20 preoperatively and 0.89+/-0.16 postoperatively (p=0.008). MRSE was -0.54+/-3.29 D preoperatively and -1.30+/-3.05 D postoperatively (p=0.45). CONCLUSIONS: Corneal topographic changes caused by the pterygium are almost reversible after surgical treatment. Successful pterygium surgery significantly reduces topographic astigmatism, SRI, SAI, and corneal flattening. However, precise prediction of these refractive changes is not always accurate.     

Limbal relaxing incisions versus on-axis incisions to reduce corneal astigmatism at the time of cataract surgery

PURPOSE: To compare limbal relaxing incisions (LRIs) with placement of the corneal cataract incision on the steepest keratometric axis for the reduction of preexisting corneal astigmatism at the time of cataract surgery. SETTING: The Queen Elizabeth Hospital, Adelaide, South Australia, Australia. METHODS: In a prospective single center study, patients having 1.5 diopters (D) or more of keratometric astigmatism were randomly assigned to 2 surgical techniques: on-axis incisions (OAIs) consisting of a single clear corneal cataract incision centered on the steepest corneal meridian or LRIs consisting of 2 arcuate incisions straddling the steepest corneal meridian and a temporal clear corneal incision. Vector analysis of the target axis flattening effect was used to assess the efficacy of treatment. RESULTS: Seventy-one eyes of 71 patients were evaluated, 33 in the OAI group and 38 in the LRI group. Six weeks postoperatively, the flattening effect was 0.41 D (median and interquartile range 0.15 to 0.78 D) in the OAI group and 1.21 D (range 0.43 to 2.25 D) in the LRI group (P = .002). After 6 months, the flattening effect was 0.35 D (range 0.00 to 0.96 D) and 1.10 D (range 0.25 to 1.79 D), respectively (P = .004). CONCLUSION: The amount of astigmatism reduction achieved at the intended meridian was significantly more favorable with the LRI technique, which remained consistent throughout the follow-up period.     

Para-limbic relaxing incisions for reduction of astigmatism within the scope of catarct surgery

PURPOSE: Limbal relaxing incision (LRI) is an easy and safe procedure to reduce astigmatism. It should be clarified, whether the effect is discussed controversely, because the varying corneal diameter and consequently the varying LRI position was not considered. PATIENTS AND METHODS: 56 patients aged 76 +/- 9 years with preoperative astigmatism of 1.6 D (0.6 to 7.0 D) underwent an almost astigmatically neutral cataract procedure (3.2 mm temporal clear corneal phacoemulsification with foldable lens implantation) and received independently from the given corneal diameter limbus related relaxing incisions of 80 degrees length and 0.6 mm depth. We performed the paired LRI in 4.5 mm, 5 mm and 5.5 mm distance from the corneal center on the steeper meridian. RESULTS: 4.3 months postoperatively we observed an astigmatic reduction of -1.0 D (-0.1 to -3.2 D) following LRI with a 9 mm optical zone, LRI with 10 mm diameter led to an astigmatic reduction of -0.4 D (-0.1 to -2.9 D) and LRI with 11 mm diameter were followed by an astigmatic reduction of -0.3 D (+0.5 to -1.1 D). Undercorrections were more frequently observed in younger patients, overcorrections more in elderly people. CONCLUSION: The application of three different kinds of limbus related relaxing incisions, with 4.5, 5 and 5.5 mm distance from the corneal center or 9, 10 and 11 mm optical zone respectively, corresponds to the variable anatomic situation of the limbus, therefore leading to nearly predictable data and explaining the divergent results of previous reports. The nearer the LRI is applied to the corneal center, the stronger is the relaxing effect.     

Correction of low corneal astigmatism in cataract surgery

AIM: To evaluate and compare aspheric toric intraocular lens (IOL) implantation and aspheric monofocal IOL implantation with limbal relaxing incisions (LRI) to manage low corneal astigmatism (1.0-2.0 D) in cataract surgery.METHODS:A prospective randomized comparative clinical study was performed. There were randomly recruited 102 eyes (102 patients) with cataracts associated with corneal astigmatism and divided into two groups. The first group received toric IOL implantation and the second one monofocal IOL implantation with peripheral corneal relaxing incisions. Outcomes considered were:visual acuity, postoperative residual astigmatism, endothelial cell count, the need for spectacles, and patient satisfaction. To determine the postoperative toric axis, all patients who underwent the toric IOL implantation were further evaluated using an OPD Scan III (Nidek Co, Japan). Follow-up lasted 6mo.RESULTS: The mean uncorrected distance visual acuity (UCVA) and the best corrected visual acuity (BCVA) demonstrated statistically significant improvement after surgery in both groups. At the end of the follow-up the UCVA was statistically better in the patients with toric IOL implants compared to those patients who underwent implantation of monofocal IOL plus LRI. The mean residual refractive astigmatism was of 0.4 D for the toric IOL group and 1.1 D for the LRI group (P<0.01). No difference was observed in the postoperative endothelial cell count between the two groups.CONCLUSION: The two surgical procedures demonstrated a significant decrease in refractive astigmatism. Toric IOL implantation was more effective and predictable compared to the limbal relaxing incision.     

角膜地形图引导下白内障手术切口对角膜散光的矫正

目的:比较不同位置和形态的手术切口对白内障摘除术后角膜散光及裸眼视力的影响。方法:选取术前角膜散光值>1.00D的白内障患者43例52眼,将患者随机分成两组,A组患者采用超声乳化白内障吸除联合人工晶状体植入术,手术切口为位于上方10∶30～11∶30的透明角膜隧道切口。B组患者采用手法碎核白内障摘除联合人工晶状体植入术,其中角膜散光值为1.00～2.00D的患者,切口为位于角膜最大屈光度径线的直线形巩膜隧道切口,长度为6.0～7.0mm,角膜散光值>2.00D的患者,在上述直线形切口对侧角膜缘处,另作一弧形板层松解切口。分别于术后2wk,3mo随访患者,检查裸眼视力及行角膜地形图检查。结果:B组患者术后2wk,3mo裸眼视力好于A组。B组患者术后角膜散光度在术后2wk,3mo时均小于A组。结论:位于角膜最大屈光度径线的6.0～7.0mm直线形巩膜隧道切口,及此切口联合作对侧弧形板层松解切口均能有效矫正白内障术前存在的角膜散光,能够使患者获得更好的术后裸眼视力。     

多焦点IOL植入联合角膜松解切口矫正白内障合并角膜散光的分析

目的:比较多焦点IOL植入联合角膜切口矫正散光与单焦点IOL植入术治疗白内障合并低度散光患者的视觉质量差异。方法:选取老年性白内障合并低度散光患者80例100眼,按随机原则分为对照组及干预组,各40例50眼。干预组行最陡角膜散光轴向上做一对透明角膜松解切口,同时按常规行透明角膜切口白内障超声乳化+多焦点IOL植入术;而对照组仅行透明角膜切口白内障超声乳化+单焦点IOL植入术。分别于术后1d;1wk;1,3mo观察两组术眼的角膜散光情况及裸眼远视力(uncorrected distance visual acuity,UCDVA),裸眼近视力(uncorrected near visual acuity,UCNVA);3mo时最佳矫正远视力(best corrected distance visual acuity,BCDVA)、最佳矫正近视力(best corrected near visual acuity,BCNVA)及最佳矫正远视力下最佳矫正近视力(distant corrected near visual acuity,DCNVA)并进行统计分析。结果:术后UCDVA和UCNVA干预组均高于对照组,而各时期角膜散光干预组均低于对照组。两组患者术后3d均有明显改善。术后1wk;1,3mo,UCDVA和UCNVA及3mo时BCDVA,BCNVA无显著差异。结论:多焦点IOL植入联合透明角膜松解切口可有效矫正白内障术前散光,提高全程视力,从而扩大多焦点IOL适用人群。     

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.     

Corneal topographic changes induced by different oblique cataract incisions

PURPOSE: To compare astigmatic and topographic changes induced by different oblique cataract incisions. SETTING: Department of Ophthalmology, Hospital of San Donà di Piave, Venice, Italy. METHODS: One hundred sixty-eight eyes having phacoemulsification were randomly assigned to 1 of 3 groups: 3.5 mm clear corneal incision (CCI), 60 eyes; 5.5 mm sutured CCI, 54 eyes; 5.5 mm scleral tunnel, 54 eyes. Incisions lay on the 120 degree semimeridian. Corneal topography was performed preoperatively and 1 week and 1 and 3 months postoperatively. Simulated keratometric readings were used to calculate astigmatism amplitude and surgically induced astigmatism (SIA). Postoperative topographic changes were determined by subtracting the preoperative from the postoperative numeric map readings. RESULTS: Three months postoperatively, the mean SIA in the right and left eyes, respectively, was 0.68 diopter (D) +/- 1.14 (SD) and 0.66 +/- 0.52 D in the 3.5 mm CCI group, 1.74 D +/- 1.43 D and 1.64 +/- 1.27 D in the 5.5 mm CCI group, and 0.46 +/- 0.56 D and 0.10 +/- 1.08 D in the scleral tunnel group. Right and left eyes showed similar SIA amplitude but different SIA axis orientation. The SIA was significantly higher in the 5.5 mm CCI group than in the other 2 groups 1 and 3 months postoperatively (P <.01). All groups showed significant wound-related flattening and nonorthogonal steepening at 2 opposite radial sectors. Topographic changes were significantly higher in the 5.5 mm CCI group and significantly lower in the scleral tunnel group. CONCLUSIONS: Right and left eyes showed similar SIA amplitude but different SIA axis orientation and topographic modifications, probably because of the different superotemporal and superonasal corneal anatomic structure. The 5.5 mm CCI induced significantly higher postoperative astigmatism, SIA, and topographic changes.     

Toric intraocular lenses for correcting astigmatism in 130 eyes

OBJECTIVE: This study evaluated the results after implantation of toric intraocular lenses (IOLs) to correct preexisting corneal astigmatism in patients undergoing either cataract or clear lens extraction surgery. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: One hundred thirty eyes of 99 patients who underwent phacoemulsification and posterior chamber toric IOL implantation from January 1997 through February 1998 were included in the study. INTERVENTION: Implantation of a toric IOL was performed after cataract surgery (122 eyes) or clear lens extraction surgery (eight eyes). Both preoperative corneal cylinder and refractive cylinder powers were more than 1.50 diopters (D) for all the eyes included in this study. To provide a comparison, we also studied 51 eyes of 45 patients meeting the same preoperative criteria for degree of corneal and refractive cylinder who underwent implantation of a spherical (nontoric) IOL combined with limbal relaxing incisions. The data for both study and comparison groups were analyzed retrospectively. The selection for the two groups was arbitrary. MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA), mean spherical equivalent, residual refractive cylinder, and toric IOL axis. RESULTS: In the toric IOL group, 84% of eyes achieved 20/40 or better UCVA. In the spherical IOL group, 76% achieved 20/40 or better UCVA. The mean postoperative refractive cylinder was -1.03 +/- 0.79 D in the toric IOL group and -1.49 +/- 0.75 D in the spherical IOL group. CONCLUSIONS: Our results indicate that phacoemulsification and posterior chamber toric IOL implantation is a largely predictable new surgical option to correct preexisting corneal astigmatism in cataract or clear lens extraction surgery.     

Sutured piggyback toric intraocular lenses to correct high astigmatism

A 74-year-old woman presented for bilateral cataract surgery, which was performed 3 days apart. Corneal astigmatism was 4.25 diopters (D) in the right eye and 4.87 D in the left. After cataract extraction through 6.0 mm scleral incisions, 2 toric, plate-haptic, silicone intraocular lenses (IOLs), each with a 3.50 D cylinder add power (2.30 D at spectacle plane), were sutured together and implanted in the bag. Both eyes had limbal relaxing incisions postoperatively. Four months postoperatively, corneal astigmatism was 4.50 D in the right eye and 4.00 D in the left. Refractive astigmatism was 0.50 D with an uncorrected visual acuity of 20/40 in both eyes. No IOL rotation was observed. Suturing toric lenses together allows greater correction of astigmatism without concern about counter rotation of the lenses.     

Optimal incision sites to obtain an astigmatism-free cornea after cataract surgery with a 3.2 mm sutureless incision.

PURPOSE: To determine the optimal incision to eliminate astigmatism after cataract extraction. SETTING: Hara Eye Hospital, Utsunomiya, Japan. METHODS: Patients having cataract extraction through a 3.2 mm corneal limbal incision without limbal sutures were divided into 2 groups. Group 1 comprised 98 eyes of 80 patients without preoperative astigmatism and Group 2, 72 eyes of 62 patients with no astigmatism postoperatively. In Group 1, the incisions that caused postoperative corneal changes were retrospectively evaluated. In Group 2, the types of incisions that induced an astigmatism-free cornea postoperatively were retrospectively studied. Patients were examined preoperatively and 6 months postoperatively. RESULTS: In Group 1, 23 of 40 eyes (57.5%) with an incision between 9 and 12 o'clock (BENT incision) and 10 of 58 eyes (17.2%) with an incision at 12 o'clock remained astigmatism free postoperatively (P <.0001). One eye (2.5%) with a BENT incision and 17 (29.3%) with a 12 o'clock incision had astigmatism greater than 1.0 diopter (D) postoperatively (P <.001). In Group 2, 72 eyes had less than 1.2 D of preoperative astigmatism. No eye with more than 1.2 D of astigmatism was astigmatism free postoperatively, even when the incision was made at the steepest meridian. CONCLUSIONS: The results indicate that to reduce astigmatism in eyes with preoperative astigmatism of 0.5 D or more, a limbal 3.2 mm BENT incision should be placed at 10:30 o'clock. To prevent astigmatism postoperatively, the incision should be placed at the steepest meridian in eyes with preoperative astigmatism greater than 0.5 D; for preoperative astigmatism greater than 1.2 D, a 3.2 mm incision at the corneal limbus is insufficient and a wider incision or an additional incision is required.     

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.     

非球面和球面人工晶状体植入术后视功能观察

目的 分析白内障患者术前角膜散光情况评估经不同位置透明角膜切口行超声乳化术后的角膜散光变化情况.方法 218例(295只眼)白内障患者分为三组,第一组选择颞侧切口,第二组选择颞上方切口,第三组选择上方切口,三组患者通过透明角膜切口行白内障超声乳化及折叠式后房型人工晶体植入术.术前及术后一周、一月、三月分别检测患者角膜散光情况,并通过Holladay-Cravy-Koch方法 计算术源性散光.结果 术前角膜散光0.5至1.5D的占60.68%,大于等于1.5D的占11.86%,顺归散光占29.49%,逆归散光占51.19%,其余为斜轴散光.术后三次随访颞侧切口组的术源性散光最低,上方切口组的术源性散光最高,具有统计学差异(P<0.05).另外,在上方切口组中发现患者术后角膜散光有向逆归散光转变的趋势.结论 白内障患者术前大多存在小于1.5D的角膜散光.在白内障术后早期阶段,颞侧透明角膜切口引起的术源性散光较小,而上方透明角膜切口不仅可引起较显著的术源性散光,并且术后角膜散光有向逆归散光转变的趋势.

Abstract：

Objective To analyze the corneal astigmatism before cataract surgery and evaluate the astigmatism changes after cataract surgery performed using clear corneal incisions with different locations.Methods: This randomized prospective clinical study comprised 295 eyes of 218 patients having phacoemulsification and implantation of foldable intraocular lens through a corneal tunnel incision. Patients were randomly divided into three groups depending on the different locations of the incision: temporal, superotemporal and superior. Corneal topography was performed preoperatively and 1 week, 1 month, and 3 months postoperatively. Surgically induced changes were calculated by vector analyses using the Holladay-Cravy-Koch method. Results: Preoperatively, in 60.68% of eyes, corneal astigmatism was between 0.5 and 1.5 diopters (D) and in 11.86%, it was 1.5 D or higher. Meanwhile, about 29.49 percent of eyes had with-the-rule (WTR) astigmatism, while 51.19% had against-the-rule (ATR) astigmatism, and the others had oblique astigmatism. At three follow-up visits postoperatively, the mean magnitude of surgically-induced astigmatism (SIA) was lowest in the temporal incision group and highest in the superior incision group. In addition, an ATR shift was found in the superior incision group. Conclusions: Corneal astigmatism less than 1.5 D was present in most cataract surgery candidates. Cataract surgery using temporal clear corneal incision induced significantly less SIA in the early postoperative period. Superior incision may lead to an ATR astigmatism shift.     

Corneal aberrations after microincision cataract surgery

PURPOSE: To study the effect of microincision cataract surgery (MICS) on the optical quality of the cornea, characterized in terms of Seidel aberrations. SETTING: Instituto Oftalmológico de Alicante, Vissum, Alicante, Spain. METHODS: This study comprised 25 eyes of 25 patients with nuclear or corticonuclear cataract of grade 2+ to 4+ (Lens Opacities Classification System III). Microincision cataract surgery was performed using low ultrasound power through a 1.6 to 1.8 mm clear corneal incision placed on the axis of the positive corneal meridian. An Acri.Smart 48S intraocular lens (Acri.Tec) was implanted in all eyes. Seidel aberration root-mean-square (RMS) values were obtained with a 6.0 mm aperture using the CSO topographer (Costruzione Strumenti Oftalmici) preoperatively and 1 and 3 months postoperatively. RESULTS: The total RMS after MICS decreased slightly from a mean of 2.15 microm +/- 2.51 (SD) preoperatively to 1.96 +/- 2.01 microm postoperatively; the decrease was not statistically significant (P = 1.00). The difference between the corneal astigmatism from preoperatively (-0.80 +/- 0.76 diopter [D]) to postoperatively (-0.63 +/- 0.62 D) was not statistically significant (P = 1.00) nor were the differences in Seidel aberrations, coma, or higher-order aberrations. CONCLUSION: Microincision cataract surgery did not degrade the optical quality of the cornea or induce a modification in corneal astigmatism, including the axis.     

小切口白内障术后的早期角膜地形图分析

目的：研究白内障小切口术后角膜形态变化特点。方法：用角膜地形图对27例（34眼）白内障小切口手术患者进行检查,分析其术前,术后1周、1月、3月的角膜地表图变化。结果：术后1周仅产生手术源性散光0.52D,术后1月角膜散光及CIM值（角膜不规则系数）趋向稳定,裸眼视力≥0.5占26眼（76.42%）,SF值（角膜形状系数）术前术后无明显变化。结论：小切口具有早期角膜形态变化小、散光稳定、视力恢复快等优点,角膜地形图可准确全面反映白内障术后角膜形态变化。