Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 27  |  Issue : 2  |  Page : 48-55

Visual Outcome of Phacoemulsification with Multifocal Toric Intraocular Lens Implantation in “With the Rule” and “Against the Rule” Corneal Astigmatism: A Case Series


1 Command Hospital (WC), Chandimandir, Chandigarh, Haryana, India
2 Armed Forces Medical College, Pune, India

Date of Submission01-Apr-2019
Date of Decision06-May-2018
Date of Acceptance10-Sep-2019
Date of Web Publication07-Feb-2020

Correspondence Address:
Dr. P K Chaturvedi
Command Hospital (WC), Chandimandir, Chandigarh, Haryana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njo.njo_10_19

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  Abstract 


Phacoemulsification with implantation of multifocal toric intraocular lens (IOL) is now a well-established modality to treat cataract and corneal astigmatism in a single surgical procedure. The visual outcome of these multifocal toric IOLs has been deliberated in this study in corneas with preexisting With the Rule (WTR) and Against the Rule (ATR) astigmatism. Material and Method: Patients of either sex with diagnosed cataract in the age group 40–65 years and preoperative anterior corneal surface astigmatism between ±1.0 D and ±3.0 D suitable to be implanted with multifocal toric IOL were included in this study. The subjects were divided in WTR (n = 17) and ATR (n = 13) groups. After undergoing cataract surgery, their unaided distant visual acuity (UCDVA) and unaided near visual acuity (UCNVA) in log MAR scale were recorded on day 1, 1 week, 4 weeks, 8 weeks, and 12 weeks postoperatively. At 8 weeks and 12 weeks postoperatively, keratometry and refraction readings were also recorded and astigmatism was measured. Observation and Result: Mean UCDVA of both groups together at 4 weeks post-op was 0.088 (SD 0.098). At 8 weeks and 12 weeks postoperative period, the results were similar with mean UCDVA: 0.030 (SD 0.068). UCDVA was significantly better in ATR group group (0.014 ± 0.014) when compared with WTR group (0.042 ± 0.01). UCNVA was 0.33 ± 0.012 for both groups together. In WTR group, mean UCNVA was 0.34 ± 0.08 and in ATR group it was 0.31 ± 0.01 at 12 weeks postoperative period and had no statistically significant difference.

Keywords: Against the Rule, astigmatism, multifocal toric IOL, With the Rule


How to cite this article:
Chaturvedi P K, Kaushik J, Mathur V, Kumar P, Aggrawal I. Visual Outcome of Phacoemulsification with Multifocal Toric Intraocular Lens Implantation in “With the Rule” and “Against the Rule” Corneal Astigmatism: A Case Series. Niger J Ophthalmol 2019;27:48-55

How to cite this URL:
Chaturvedi P K, Kaushik J, Mathur V, Kumar P, Aggrawal I. Visual Outcome of Phacoemulsification with Multifocal Toric Intraocular Lens Implantation in “With the Rule” and “Against the Rule” Corneal Astigmatism: A Case Series. Niger J Ophthalmol [serial online] 2019 [cited 2022 Aug 8];27:48-55. Available from: http://www.nigerianjournalofophthalmology.com/text.asp?2019/27/2/48/277882




  Introduction Top


Cataract has always found its place among the most common ocular disorders requiring surgical intervention. Following uncorrected refractive errors, it is second most common cause of blindness and visual impairment and that has been addressed with strategized approach that appears effective so far with evident rise in CSR (cataract surgical rate) and CSC (cataract surgical coverage) worldwide, particularly in South Asia.[1] Refractive errors have also been among the forerunner of causes for blindness and visual impairment worldwide. Astigmatism with prevalence ranging from 11.4% in Africa to 45.6% in America is the most common refractive error among adults and more so in South East Asia with prevalence rate of 44.8%.[2] When these two causes of blindness and visual impairment coexist, it compounds their adverse effects on the visual status of such individuals.[3],[4] A combined surgical approach to address and tackle both issues with a view of achieving stable predetermined postoperative refractive target is the key. While choosing to implant a premium multifocal IOL (MFIOL) in such cases, the preexisting corneal astigmatism should be considered and an appropriate modification of surgical approach in the form of additional surgical procedures such as Limbal Relaxing Incisions (LRI), PCRI, femtosecond laser-assisted astigmatic keratotomy or subsequent excimer procedures, or implanting a MF toric intraocular lens (IOL) can be considered. Due to good stability and predictability of visual outcome, MF toric IOL implantation has surpassed other options of tackling preexisting corneal astigmatism.[5] With 64.4% prevalence of corneal astigmatism between 0.25 and 1.5 D and 22.22% above that power, there is an increasing scope of using MF toric IOL for correcting astigmatism from as low as 0.25 D to almost 12 D.[6] It becomes pertinent to study the type of astigmatism and visual outcome of cataract surgery and implantation of MF toric IOL among patients with coexisting preoperative astigmatism and significant cataract. In this study, the visual outcome of MF toric IOL in eyes with preexisting with the Rule (WTR) and Against the Rule (ATR) anterior corneal astigmatism was studied.


  Material and Methods Top


This prospective nonrandomised case series study was conducted in a tertiary care hospital in north India between March 2017 and December 2017. Consecutive patients with diagnosed cataract in the age group 40–65 years and preoperative astigmatism of anterior corneal surface between ±1.0D to ±3.0D suitable to be implanted with multifocal toric IOL were included in this study. Patients with corneal scar, deposits, dystrophies, degenerations, or pervious surgery were excluded. The patients with anterior segment abnormalities like synechiae (anterior or posterior), dysgenesis, iris abnormalities, zonular dialysis, retinal pathologies, and conditions that may preclude good visual recovery were excluded. Preoperatively uncorrected distance visual acuity (UCDVA) and uncorrected near visual acuity (UCNVA) were noted. Keratometry was performed using three readings of Charops CRK 7000® Auto-refractokeratometer (Shanghai Huvitz Inc.) and their average was considered for calculation. Biometry was done using A-scan Echorule 2® (Biomedix Optotechnik and Devices Pvt. Ltd.) and IOL power spherical equivalent (SE) were calculated using the Sanders Retzlaff Kraff/Theoretical (SRK/T) formula. Multifocal toric IOL power calculations were done using online toric IOL power calculator (https://www.myalcon-toriccalc.com). Preoperatively limbal reference marks were made using a Nuijts–Solomon Toric Bubble Marker (AE 2791TBL, ASICO), in sitting position under topical anesthesia. Intraoperatively incision axis and intended axis of IOL were marked using a Mendez Degree Gauge and Nuijts–Solomon Toric Axis Marker (AE 2740N, ASICO). Thirty cases underwent phacoemulsification and implantation of Acrysof IQ ReStore Multifocal Toric IOL +3 Add (Alcon Labs, Fort Worth, TX) by a single experienced surgeon trained in cornea and refractive services, using Infiniti® Vision System (Alcon Labs, Fort Worth, TX), using the same phacoemulsification technique, superior site at 105° and triplanar configuration of 2.2 mm corneal incision. Patients were given a combination of topical steroid and antibiotic in weekly tapering schedule for one month. UCDVA and UCNVA were recorded on day 1 and then at 1 week, 4 weeks, 8 weeks, and 12 weeks postoperatively. At 8 weeks and 12 weeks postoperatively, keratometry and refraction readings were also recorded and astigmatism was measured.


  Observation and Result Top


Thirty cases were divided into two groups: WTR (With the Rule) (n = 17) and ATR (n = 13) based on the type of astigmatism. The data were collected on requisite forms from the patients after taking their consent voluntarily. The collected data were organized into data sheet in MS-Excel. IBM SPSS 23 was used to analyze the data. The nature of data was studied using descriptive statistics like mean, standard deviation, and standard error. Repeated Measures ANOVA and Paired t-test were used to compare measurements over scheduled follow-up time as per protocol.

Mean preoperative UCDVA in all cases (WTR/ATR) was 0.893 with standard deviation of 0.284: worst was 1.78 and best was 0.60 log MAR units. At 4 weeks postoperative period, out of 30 eyes under the study, 53.3% (16) had UCDVA of 0, 43.3% (13) had UCDVA of 0.18, and 3.3% (1) had UCDVA of 0.3 log MAR units. Mean visual acuity at 4 weeks post-operatively was 0.088 with standard deviation of 0.098. At 8 weeks and 12 weeks postoperative period, the results were similar with mean UCDVA being 0.030 with standard deviation of 0.068; 83.3% (25) had UCDVA 0 and 16.6% (5) had UCDVA 0.18 log MAR units [Table 1]. Pairwise P-values of the postoperative data were found to be <0.001 and hence statistically significant.
Table 1 Changes in uncorrected distant visual acuity (logMAR units)

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t-Test between the WTR and ATR groups at 8th and 12th postoperative shows a P-value of <0.05 and hence it is statistically significant [Table 2]. In WTR group, mean preoperative UCDVA was 0.87 ± 0.05 log MAR, which improved to 0.042 ± 0.01 at 8 weeks postoperative period and remained stable thereafter. In ATR group, mean pre-op UCDVA was 0.92 ± 0.09 log MAR which improved to 0.014 ± 0.14 at 8 weeks postoperative period and remained stable thereafter [Figure 1].
Table 2 Changes in uncorrected distant visual acuity in WTR and ATR groups (log MAR units)

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Figure 1 UCDVA of ATR and WTR groups (log MAR units).

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Postoperative change in UCDVA was statistically significant. Difference in 12 week postoperative results in WTR-ATR group was statistically significant with ATR group showing better UCDVA.

The mean preoperative UCNVA for all cases (WTR/ATR) was 1.047 with standard deviation of 0.1008: worst being 1.1 and best being 0.8 [Table 3]. At 4 weeks postoperative period, 70% (21) had UCNVA of 0.3, 16.6% (5) had UCNVA of 0.4, and 13.3% (4) had UCNVA of 0.6. Mean unaided near visual acuity at 4 weeks post-op was 0.360 with standard deviation of 0.110. At 12 weeks postoperative period, the mean UCNVA was 0.333 with standard deviation of 0.066; 76.6% (23) had unaided visual acuity 0.3, 13.3% (4) had 0.4, and 10% (3) had UCNVA of 0.5 log MAR units. The change from post-op day 1 to end of 12 weeks is statistically significant (p <0.001), though stability in UCNVA has been reached by 4 weeks post-op and beyond, the values being statistically insignificant.
Table 3 Changes in uncorrected near visual acuity in all cases (log MAR units)

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Studying the changes in UCNVA in WTR and ATR groups, t-test between these two groups at 8th and 12th post-op shows no statistical significance (p > 0.05) [Table 4]. In WTR group, mean pre-op UCNVA of 1.04 ± 0.02 log MAR improved to 0.347 ± 0.08 at 12 weeks post-op. In ATR group, mean pre-op UCNVA of 1.04 ± 0.01 log MAR improved to 0.31 ± 0.01 at 12 weeks postoperative period [Figure 2].
Table 4 Changes in uncorrected near visual acuity in WTR and ATR groups (log MAR units)

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Figure 2 UCNVA of ATR and WTR groups (log MAR units).

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  CHANGES IN STEEP K Top


In WTR group, mean preoperative steep K was 45.54 ± 0.33 D, at 8 weeks 45.52 ± 0.32 D, and at 12 weeks it was 45.45 ± 0.32 D. At 12 weeks post-op, 11 eyes show minimal (<0.25 D) change in steep K, 4 eyes show change between 0.25–0.5D, and 2 eyes show ≥0.5 D. None of the eyes exhibits >0.6 D change. The mean difference in steep K at preoperative and 12 weeks postoperative period was 0.05 ± 0.08 D and was statistically insignificant with P-value >0.05. In ATR group, mean preoperative steep K was 45.15 ± 0.40 D, at 8 weeks 44.98 ± 0.39D, and at 12 weeks it was 45.05 ± 0.39 D [Figure 3]. At 12 weeks post-op, 10 eyes show minimal (<0.25 D) change in steep K, 2 eyes show change between 0.25–0.5 D and 1 eye exhibited a change of 0.9 D. The mean difference in steep K at preoperative and 12 weeks postoperative period was 0.09 ± 0.08 D and was statistically insignificant with P-value >0.05.
Figure 3 Steep K changes: ATR and WTR groups (Diopters).

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  CHANGES IN FLAT K Top


Studying changes in flat K in WTR-ATR Groups, WTR group shows mean preoperative flat K of 43.81 ± 0.35 D, at 8 weeks 43.76 ± 0.36 D, and at 12 weeks it was 43.72 ± 0.37D. At 12 weeks post-op, 11 eyes show minimal (<0.25 D) change in flat K, 2 eyes show change between 0.25 and d 0.5 D, and 4 eyes show ≥0.5 D [Figure 4]. None of the eyes did exhibit >0.55 D change. The mean difference in flat K at preoperative and 12 weeks postoperative period was 0.08 ± 0.08 D and was not statistically significant (P-value 0.318). In ATR group, mean preoperative flat K was 43.60 ± 0.40 D, at 8 weeks 43.44 ± 0.38 D, and at 12 weeks it was 43.45 ± 0.39 D. At 12 weeks post-op, 9 eyes show minimal (<0.25 D) change in flat K, 2 eyes show change between 0.25 and 0.5 D, and 2 eyes show ≥0.5 D. None of the eyes did exhibit >0.60 D change. The mean difference in flat K at preoperative and 12 weeks postoperative period was 0.15 ± 0.06 D and was not statistically significant (P-value >0.05).
Figure 4 Flat K changes: ATR and WTR groups (Diopters).

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  Corneal astigmatism Top


The mean preoperative corneal astigmatism was ±1.65 ± 0.10 D with standard deviation of ±0.52 DS, with maximum being ±2.8 D and minimum being ±1.0 DS. At 8 weeks postoperatively, the corneal astigmatism was ±1.66 D with standard deviation of ±0.54 DS, the maximum being ±2.9 D and minimum being ±1.0 DS. At 12 weeks post-op values were ±1.69 D with standard deviation of ±0.56 DS, with maximum being ±2.95 D and minimum value remaining at ±1.0 DS. Pairwise P-values of follow-up data being >0.05, this was found to be statistically insignificant [Table 5].
Table 5 Changes in corneal astigmatism

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  WTR AND ATR − CORNEAL ASTIGMATISM Top


In WTR group, the mean preoperative corneal astigmatism was ±1.73 ± 0.14 D with maximum being ±2.8 D and minimum being ±1.2 DS. At 8 weeks postoperatively, the mean corneal astigmatism was ±1.76 ± 0.15 D and at 12 weeks post-op the values were ±1.76 ± 0.16 D. The mean difference in preoperative corneal astigmatism and at 12 weeks postoperative period was 0.03 ± 0.07 D and was statistically insignificant (P-value >0.05) [Table 6].
Table 6 Corneal astigmatism (dioptres): WTR and ATR group

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In ATR group, the mean preoperative corneal astigmatism was ±1.55 ± 0.13 D with maximum being ±1.8 D and minimum being ±1.0 DS. At 8 weeks postoperatively, the mean corneal astigmatism was ±1.54 ± 0.11 D and at 12 weeks post-op the values were ±1.60 ± 0.11 D. The mean difference in preoperative corneal astigmatism and at 12 weeks postoperative period was 0.06 ± 0.78 D and was statistically insignificant (P-value >0.05) [Table 6].


  Postoperative refractive sphere Top


At 4 weeks post-op, the mean refractive sphere was ±0.225 ± 0.04D, at 8 weeks it was ±0.16 ± 0.02D, and at 12 weeks refractive sphere was ±0.15 ± 0.02 D. Pairwise comparison of refractive sphere at 4–8 weeks and 4–12 weeks was statistically significant (P-value <0.05). Pairwise test between 8 and 12 weeks was insignificant (P-value > 0.05) [Table 7].
Table 7 Postoperative refractive sphere (dioptres): All cases

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  WTR AND ATR − POST OPERATIVE REFRACTIVE SPHERE Top


In WTR group, at 4 weeks post-op, the mean refractive sphere was ±0.25 ± 0.06 D, at 8 weeks it was ±0.17 ± 0.04 D, and at 12 weeks refractive sphere was ±0.14 ± 0.03 D. Pairwise comparison of refractive sphere at 4–8weeks and 4–12 weeks was statistically insignificant with P-values 0.096 and 0.090, respectively. Pairwise test between 8–12 weeks was insignificant with P-value of 0.431, whereas between 1 and 12 weeks it was significant with P-value <0.05.

In ATR group, at 4 weeks post-op, the mean refractive sphere was ±0.19 ± 0.05 D, whereas at 8 and 12 weeks it was ±0.15 ± 0.03 D. Pairwise comparison of refractive sphere at 4–8/12 weeks was statistically insignificant (P-value 0.165). Pair-wise comparison of refractive sphere at 1–12 weeks was significant (P-value <0.05) [Table 8].
Table 8 Post-operative refractive sphere (dioptres): WTR and ATR group

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  WTR AND ATR − POSTOPERATIVE REFRACTIVE CYLINDER Top


In WTR group, at 4 weeks post-op, the mean refractive cylinder was ±0.35 ± 0.05 D, at 8 weeks it was ±0.26 ± 0.03 D, and at 12 weeks refractive cylinder was ±0.26 ± 0.04 D. Pairwise comparison of refractive cylinder at 4–8 weeks, 4–12 weeks, and 1–12 weeks was statistically significant (P-value <0.05), whereas pairwise test between 8 and 12 weeks was insignificant (P-value >0.05) [Table 9]; [Figure 5].
Table 9 Post-operative refractive cylinder (dioptres): WTR and ATR group

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Figure 5 Refractive cylinder (WTR & ATR Group).

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In ATR group, at 4 weeks post-op, the mean refractive cylinder was ±0.38 ± 0.08 D, at 8 weeks it was ±0.31 ± 0.06D, and at 12 weeks refractive cylinder was ±0.27 ± 0.05 D. Pairwise comparison of refractive cylinder at 4–8 weeks, 4–12 weeks, and 8–12 weeks was statistically insignificant (P-values > 0.05), though pairwise test between 1and 12 weeks was statistically significant (P-value <0.05) [Table 9]; [Figure 5].


  Discussion Top


With broadening horizon of options to achieve near physiologically normal visual performance after cataract surgery and IOL implantation, it is now feasible to correct the naturally occurring abnormalities with the aim of achieving a stable and near perfect refraction and vision. Implantation of MF toric IOLs in eyes with preexisting corneal astigmatism is a known step toward this goal. The implantation of MF toric IOLs in this case series with preexisting corneal astigmatism (ATR/WTR) showed that 53.3% achieved 0 log MAR (20/20) vision in early postoperative period increasing to 83.3% by week 12 with mean 0.03 ± 0.068 log MAR, which was better than mean UCDVA of 0.10 ± 0.14 log MAR as reported by Waltz et al.,[7] 0.15 ± 0.17 log MAR by Visser et al.,[8] 0.06 ± 0.14 log MAR by Zhang et al.,[9] and 0.1 ± 0.14 log MAR in Gangwani et al.[5] Correction of corneal astigmatism with toric IOLs appears more physiological and stable with predictable outcome when compared to other adjunctive surgical modalities.[10] As studied by Freitas et al.,[11] combining nontoric IOLs with limbal relaxing incisions had shown successful achievement of target correction in only 43.74% cases when compared to 76.67% among toric IOLs and a better mean UCDVA in multifocal toric IOLs as brought out by Gangwani et al.[5] In this study, eyes with WTR corneal astigmatism mean UCDVA improved to 0.042 ± 0.01 at 8 weeks postoperative period and in ATR group, it was to 0.014 ± 0.14 at 8 weeks post-op, which is better than what was observed by Gangwani et al.[5] The UCNVA in WTR group, mean pre-op UCNVA of 1.04 ± 0.02 log MAR improved to 0.347 ± 0.08 at 12 weeks post-op. In ATR group, mean pre-op UCNVA of 1.04 ± 0.01 log MAR improved to 0.31 ± 0.01 at 12 weeks postoperative period. A better outcome of UCDVA in ATR eyes does not commensurate with Ninomiya et al.[12] which found a equivocal visual outcome in both ATR and WTR group with monofocal toric IOLs after one year follow up. The cause of good visual recovery in ATR group eyes in our study may be attributed to adverse effect of pre-operative blur produced in the perception of horizontal stimuli by ATR astigmatism. This ATR astigmatism when compensated with the mutifocal toricity at the corneal plane, provides a better perception of image by visual cortex which is already neuro-adapted to long standing blur attributed to anterior corneal surface ATR astigmatism in addition to ATR astigmatism contributed by the posterior corneal surface,[13],[14] particularly with higher keratometric readings of the anterior corneal surface. The UCNVA was almost equal in both WTR and ATR astigmatic groups, and there has been no statistical difference in the NVA in both groups. Mean UCNVA at 12 weeks postoperative period was 0.33 ± 0.06 log MAR (WTR group: 0.34 ± 0.08; ATR group 0.31 ± 0.01) in our study, which is better than 0.43 ± 0.11 found by Gangwani et al.[5]

The stability of NV was established by 4 weeks postoperatively, beyond which there was no significant change. All the patients were spectacle independent for routine near vision activities. Effect of keratometric changes affecting the outcome appears insignificant as the difference in changes in steep K and flat K in both WTR and ATR are not statistically significant. In this study, the multifocal toric IOLs had better visual outcome among the eyes with preexisting “Against the Rule” corneal astigmatism; however, a larger sample size is recommended with similar and other models and designs of toric multifocal IOLs.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Gudlavalleti VSM, Jain BK, Shamanna BR, Subramanyam D. Improving cataract services in the Indian context. Community Eye Health 2014;27(85):4-5.  Back to cited text no. 1
    
2.
Hashemi H, Fotouhi A, Pakzad R, Ostadimoghaddam H, Khabazkhoob M. Global and regional estimates of prevalence of refractive errors: systematic review and meta-analysis. J Curr Ophthalmol 2018; 30(1):3-22.  Back to cited text no. 2
    
3.
Ferrer-Blasco T, Montés-Micó R, Peixoto-de-Matos SC, González-Méijome JM, Cerviño A. Prevalence of corneal astigmatism before cataract surgery. J Cataract Refract Surg 2009;35(1):70-5.  Back to cited text no. 3
    
4.
Hoffmann PC1, Hütz WW. Analysis of biometry and prevalence data for corneal astigmatism in 23,239 eyes. J Cataract Refract Surg 2010;36(9):1479-85.  Back to cited text no. 4
    
5.
Gangwani V, Hirnschall N, Findl O, Maurino V. Multifocal toric intraocular lenses versus multifocal intraocular lenses combined with peripheral corneal relaxing incisions to correct moderate astigmatism. J Cataract Refract Surg 2014;40(10):1625-32.  Back to cited text no. 5
    
6.
Levitz L, Reich J, Roberts K, Hodge C. Evaluation of toric intraocular lenses in patients with low degrees of astigmatism. Asia Pac J Ophthalmol (Phila) 2015;4(5):245-9.  Back to cited text no. 6
    
7.
Waltz KL, Featherstone K, Tsai L, Trentacost D. Clinical outcomes of TECNIS toric intraocular lens implantation after cataract removal in patients with corneal astigmatism. Ophthalmology 2015;122(1):39-47.  Back to cited text no. 7
    
8.
Visser N, Beckers HJ, Bauer NJ, Gast ST, Zijlmans BL et al. Toric vs. aspherical control intraocular lenses in patients with cataract and corneal astigmatism: a randomized clinical trial. JAMA Ophthalmol 2014;132:1462-8.  Back to cited text no. 8
    
9.
Zhang JS, Zhao JY, Sun Q, Ma LW. Distance vision after bilateral implantation of AcrySof toric intraocular lenses: a randomized, controlled, prospective trial. Int J Ophthalmol 2011;4:175-8.  Back to cited text no. 9
    
10.
Kessel L, Andresen J, Tendal B, Erngaard D, Flesner P, Hjortdal J. Toric intraocular lenses in the correction of astigmatism during cataract surgery: a systematic review and meta-analysis. Ophthalmology 2016; 123(2):275-86.  Back to cited text no. 10
    
11.
Freitas GO, Boteon JE, Carvalho MJ, Pinto RM. Treatment of astigmatism during phacoemulsification. Arq Bras Oftalmol 2014;77(1):40-6.  Back to cited text no. 11
    
12.
Ninomiya Y, Minami K, Miyata K, Eguchi S, Sato R, Okamoto F et al. Toric intraocular lenses in eyes with With-the-Rule, Against-the-Rule, and oblique astigmatism: one-year results. J Cataract Refract Surg 2016;42(10):1431-40. doi: 10.1016/j.jcrs.2016.07.034.  Back to cited text no. 12
    
13.
Koch DD, Ali SF, Weikert MP, Shirayama M, Jenkins R, Wang L. Contribution of posterior corneal astigmatism to total corneal astigmatism. J Cataract Refract Surg 2012;38:2080-7.  Back to cited text no. 13
    
14.
Koch DD, Jenkins RB, Weikert MP, Yeu E, Wang L. Correcting astigmatism with toric intraocular lenses: effect of posterior corneal astigmatism. J Cataract Refract Surg 2013;39:1803-9.  Back to cited text no. 14
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9]



 

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Abstract
Introduction
Material and Methods
Observation and ...
CHANGES IN STEEP...
CHANGES IN FLAT ...
Corneal astigmatism
WTR AND ATR W...
Postoperative re...
WTR AND ATR W...
WTR AND ATR W...
Discussion
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