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Table of Contents
ORIGINAL ARTICLE
Year : 2022  |  Volume : 4  |  Issue : 1  |  Page : 11

Safety and efficacy of manual small incision cataract surgery and phacoemulsification: a retrospective, comparative study in a low-to-middle-income country


1 Department of Ophthalmology, Visualiza Clinic, Guatemala, Guatemala; Department of Cornea and Anterior Segment, Instituto de Microcirugía Ocular, Barcelona, Spain
2 Department of Research, University of California San Diego, San Diego, CA, USA
3 Department of Ophthalmology, Visualiza Clinic, Guatemala, Guatemala
4 Department of Cornea and Anterior Segment, Instituto de Microcirugía Ocular, Barcelona, Spain; Department of Ophthalmology, Hospital CUF Cascais, Cascais; Department of Research,NOVA Medical School,Faculdade de Ciências Médicas – Universidade Nova de Lisboa, Lisbon, Portugal

Date of Submission18-Oct-2021
Date of Decision16-Dec-2021
Date of Acceptance17-Dec-2021
Date of Web Publication23-Mar-2022

Correspondence Address:
Dr. Mario Renato Papa-Vettorazzi
5TA AV. 11-44 Zona 9, 01009, Guatemala

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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/pajo.pajo_115_21

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  Abstract 


Purpose: To compare the efficacy and safety of manual small incision cataract surgery (mSICS) versus phacoemulsification in a referral center from a low-to-middle-income country.
Subjects and Methods: A retrospective cohort of 177 eyes with visually significant cataract and ≤1.0 diopter (D) of keratometric astigmatism was intervened during 2017 by four surgeons either by mSICS or by phacoemulsification. Last follow-up was at 4–6 weeks. Outcome measures included postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive cylinder, spherical equivalent (SE), complications, and re-interventions.
Results: The mSICS group included 107 eyes; the phacoemulsification group included 70 eyes. UDVA was comparable between both groups; 89.6% in the mSICS group and 95.7% in the phacoemulsification group achieved a UDVA ≥6/18 (20/60) (P = 0.06). CDVA was comparable between both groups; 100% in the mSICS cohort and 98.6% in the phacoemulsification cohort had a CDVA ≥6/18 (20/60) (P = 0.26). Although the absolute difference in postoperative refractive astigmatism between both groups was small, it was statistically significant in favor of the phacoemulsification group (P = 0.02). Postoperative refractive SE was also comparable between both cohorts (P = 0.64). One intraoperative complication was found in the phacoemulsification group (1.4%), with no complications in the mSICS group. However, there were six reoperations in the mSICS cohort (5.6%) and no reoperations in the phacoemulsification one.
Conclusions: Both mSICS and phacoemulsification achieved excellent visual outcomes with low complication rates. Phacoemulsification gives better UDVA and lower postoperative refractive astigmatism in a larger proportion of patients at 4–6 weeks.

Keywords: Cataract surgery, manual small incision cataract surgery, phacoemulsification


How to cite this article:
Papa-Vettorazzi MR, Cruz-Rodríguez JB, Silva-Linares GL, Moura-Coelho N, Yee-Melgar N. Safety and efficacy of manual small incision cataract surgery and phacoemulsification: a retrospective, comparative study in a low-to-middle-income country. Pan Am J Ophthalmol 2022;4:11

How to cite this URL:
Papa-Vettorazzi MR, Cruz-Rodríguez JB, Silva-Linares GL, Moura-Coelho N, Yee-Melgar N. Safety and efficacy of manual small incision cataract surgery and phacoemulsification: a retrospective, comparative study in a low-to-middle-income country. Pan Am J Ophthalmol [serial online] 2022 [cited 2022 Oct 7];4:11. Available from: https://www.thepajo.org/text.asp?2022/4/1/11/340381




  Introduction Top


Although phacoemulsification is considered the standard of care for cataract surgery, a less expensive technique in terms of capital equipment investment, equipment maintenance, and disposable costs per case seems like the best option in developing countries with low-income populations, where a growing backlog of blindness due to cataract has resulted from insufficient healthcare access and resources.[1],[2]

Sutureless manual small incision cataract surgery (mSICS) may be faster and better suited for the advanced mature cataracts that typify underserved populations.[3] It is considered a high-volume, low-cost, high-quality procedure, making it a very good alternative in terms of cost-effectiveness compared with phacoemulsification.[4]

Outcomes of mSICS have been reported previously in studies mainly from India and Nepal. However, these studies had small populations, and there are no data available regarding Latin-American countries.[5],[6] The lack of scientific information, mainly in the region of Central America, makes it unable to generate accurate recommendations for patients with cataract in this particular geographic zone. According to several publications, mSICS outcomes in terms of visual rehabilitation and complications are comparable to phacoemulsification outcomes.[4],[7],[8],[9]

The aim of this study was to compare the efficacy and safety profiles between mSICS and phacoemulsification in a high-volume clinic from a low- to middle-income country.

We assessed the outcomes in terms of uncorrected distance visual acuity (UDVA), best-corrected distance visual acuity (CDVA), postoperative refractive spherical equivalent (SE), postoperative refractive astigmatism, surgical complications, and reoperations.


  Subjects And Methods Top


Study design

We performed a single-center, retrospective review of all patients with a visual impairing cataract and no other ocular condition who underwent cataract surgery either by mSICS (Group 1) or by phacoemulsification (Group 2) between January and December 2017. The aim of this work was to compare both techniques (mSICS and phacoemulsification) in similar cohorts; therefore, the eyes included for this study in the mSICS group were eyes that did not had advanced cataracts. This study followed the tenets of the Declaration of Helsinki; “Given the retrospective nature of the work, an ethics committee approval was waived.”.

Patients were allotted for mSICS or phacoemulsification based on lens density assessed by clinical evaluation or according to the patient's preference regarding their financial condition. Inclusion criteria included CDVA ≤20/30, ≤1.00 D of keratometric astigmatism measured by corneal tomography (Galilei G6, Ziemer Ophthalmic Systems). Exclusion criteria included ≥1.00 D of keratometric astigmatism, axial length <22.0 mm and >25.5 mm, and other ocular comorbidities (glaucoma, retinopathy, and significant corneal opacities). Optical biometry was performed in all cases (Galilei G6, Ziemer Ophthalmic Systems), and a monofocal nontoric intraocular lens (IOL) was selected for each case using the SRK-T formula.

The following preoperative variables were collected: age, gender, laterality, UDVA, CDVA, SE, refractive astigmatism, and keratometric astigmatism. Surgical data collected and analyzed included incision site and intraoperative complications. Postoperative variables collected and analyzed included reoperation rate, UDVA, CDVA, SE, and refractive astigmatism. Visual acuity was determined using a Snellen visual acuity chart. Because some visual acuities were expressed in nonnumerical terms, they were converted to logMAR scale for their analysis[10] [Annex A].



Surgical procedure

All surgeries were performed by four surgeons (who were allotted equally to both groups) during 2017 under local peribulbar anesthesia and sedation administered by an anesthesiologist.

The surgical procedures of mSICS and phacoemulsification have been previously described. Standard mSICS was performed through a 6.0–6.5-mm sclerocorneal tunnel. The location of the frown incision was decided according to preoperative keratometry. A large continuous curvilinear capsulorhexis (6.0–7.0 mm) was performed followed by hydrodissection. The nucleus was prolapsed into the anterior chamber and extracted in one piece using an irrigation vectis. Cortical material was removed with a Simcoe cannula. After implantation in the capsular bag of a polymethyl methacrylate monofocal IOL, the anterior chamber was pressurized and the wound was left unsutured. The conjunctiva was closed using diathermy.

Standard phacoemulsification was performed through a 3.2-mm limbal incision. A 5.0-mm capsulorhexis was performed followed by hydrodissection. Depending on the surgeon's preference, a divide-and-conquer or stop-and-chop technique was used. Cortical material was removed with automated irrigation/aspiration. A foldable hydrophilic or hydrophobic monofocal IOL was implanted in the capsular bag, the anterior chamber was pressurized, and the wound was left unsutured. No intracameral antibiotics were used at the end of surgery in either group.

Postoperative care

All eyes were shielded once the procedure was finished. Every patient used combined ciprofloxacin 0.3% + dexamethasone 0.1% or combined tobramycin 0.3% + dexamethasone 0.1% drops every 1 or 2 h while awake on the 1st day, then 4 times a day for 7 days, and then tapered slowly for 1 month unless inflammation did not resolve. Follow-up visits at 1 day, 1 week, and 4–6 weeks postoperatively were scheduled.

Statistical analysis

Main outcomes analyzed were postoperative UDVA and CDVA, predictability (percentage of eyes within ± 0.50 and ± 1.00 D of the attempted refraction), and intraoperative and postoperative complication rates. A comparative analysis of efficacy and safety outcomes was performed between both groups. Results are reported following the Standard for Reporting Refractive Outcomes of Intraocular Lens-Based Surgery.[11]

Descriptive analysis was made for all the continuous variables. The normally distributed variables are presented with mean and standard deviation; the ones that were not normally distributed are presented with median and interquartile range. For all the categorical variables, we present frequencies and proportions. According to data distribution, paired t-test or Wilcoxon signed-rank test was used to compare continuous variables. Statistical analysis was based on a two-sided significance level. Missing data were handled with the available data method. Analysis was made using STATA version 14.2 (StataCorp LLC, TX, EE. UU.). A P < 0.05 was considered statistically significant


  Results Top


Final analytic sample was 177 eyes. mSICS was performed in 107 eyes and phacoemulsification in 70 eyes. Demographic and preoperative characteristics are presented in [Table 1]. There was no statically significant difference between the groups.
Table 1: Demographic and preoperative characteristics

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In Group 1, median UDVA improved from 0.69 (0.47–1.0) logMAR to 0.17 (0.17–0.39) logMAR (P < 0.01), and median CDVA improved from 0.3 (0.3–0.54) logMAR to 0.0 (0.00–0.09) logMAR (P < 0.01). In Group 2, median UDVA improved from 0.6 (0.47–1.0) logMAR to 0.17 (0.09–0.3) logMAR (P < 0.01), and median CDVA improved from 0.3 (0.17–0.47) logMAR to 0.0 (0.0–0.09) logMAR (P < 0.01). Median change in UDVA was 0.45 logMar for Group 1 and 0.47 logMar for Group 2 (P = 0.960). Median change in CDVA was 0.3 logMar for both groups (P = 0.213). Distribution of median preoperative CDVA for both groups is presented in [Supplementary Figure 1].



The proportion of eyes with postoperative CDVA ≥6/12 (20/40) was 98% (105 eyes) for Group 1 and 97% (68 eyes) for Group 2 (P = 0.640). Moreover, a postoperative CDVA ≥6/7.5 (20/25) was achieved in 87% (93 eyes) in Group 1 and 87% (61 eyes) in Group 2 (P = 1.012). A postoperative CDVA of 6/6 (20/20) was achieved in 57% (61 eyes) in the mSICS group and in 67% (47 eyes) in the phacoemulsification group (P = 0.214).

[Table 2] presents the comparison between postoperative UDVA and CDVA between techniques; no difference was found at the last follow-up. However, a higher proportion of patients in the phacoemulsification group reached UDVA ≥20/25 (50% vs. 29%). Proportion of CDVA ≥20/25 was similar for both groups (86.9% vs. 87.1%). Difference between postoperative UDVA and postoperative CDVA for both techniques is shown in [Figure 1]b. In Group 1, UDVA was within one line of CDVA in 66.3% (71 eyes). In Group 2, 74.3% (52 eyes) achieved UDVA within one line of CDVA (P = 0.311). In Group 1, UDVA was within two lines of CDVA in 86.8% (93 eyes). In Group 2, UDVA was within two lines of CDVA in 89.1% (62 eyes) (P = 0.826) [Figure 1]b, which means that most patients had a satisfactory outcome; this is supported by the data displayed in [Figure 1]a, which shows that 75% (80 eyes) and 77% (54 eyes) had a postoperative UDVA ≥6/12 (20/40), with 98% (105 eyes) and 97% (68 eyes) achieving a postoperative CDVA ≥6/12 (20/40).
Figure 1: Standard graphs for Reporting Refractive Outcomes of Intraocular Lens–Based Surgery for both groups. (a) Cumulative postoperative uncorrected and corrected distance visual acuity for both techniques. (b) Difference between postoperative uncorrected and corrected distance visual acuity for both groups. (c) Spherical refractive accuracy of both groups. (d) Postoperative refractive cylinder for both techniques

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Table 2: Comparison of visual outcomes

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Change in CDVA for both cohorts is shown in [Figure 2]. There was no loss of ≥2 lines of CDVA in the mSICS group. In the phacoemulsification group, 2 eyes (3%) lost ≥2 lines of CDVA, but there was no statistical difference between the groups (P = 0.153). One was an eye with an intraoperative complication (posterior capsule rupture [PCR] and vitreous loss), and the other eye had mild chronic corneal edema. Although both patient groups had comparable median preoperative CDVA, we cannot completely exclude that the superior vision gain in the mSCIS group was due to a slight (nonstatistically significant) worse preoperative CDVA as is suggested by the histogram in Supplementary [Figure 1]. Residual refractive SE for both types of surgery using optical biometry and the SRK-T formula is shown in [Table 3] and [Figure 1]c.
Figure 2: Change between preoperative and postoperative corrected visual acuity in Snellen lines for both groups

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Table 3: Comparison of refractive accuracy between techniques using SRK-T formula for intraocular lens calculation

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Median preoperative refractive cylinder was −1.00 D (−1.50, −0.50) in Group 1 and − 0.75 D (−1.00, −0.5) in Group 2 (P = 0.392). After cataract surgery, median refractive cylinder was − 0.75 D (−1.00, −0.50) in Group 1 (P = 0.051 compared with baseline) and −0.5 D (−0.75, −0.25) in Group 2 (P = 0.801 compared with baseline). This difference in residual astigmatism between patient groups was statistically significant in favor of the phacoemulsification group (P = 0.023). The proportion of eyes with final refractive astigmatism >1.00 D was 16% (17 eyes) in the mSICS group and 9% (6 eyes) in the phacoemulsification group (P = 0.17). We believe that the reason why a small number of eyes in both groups had a postoperative refractive astigmatism >1.0 D is because of the type and location of the incision that was performed. Data are presented in [Table 4] and [Figure 1]d.
Table 4: Refractive astigmatism after surgery

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There was one complication in the phacoemulsification group (1.4%) and no complications in the mSICS group (P = 0.392). However, there were six reoperations in the mSICS group (5.6%) and no reoperations in the phacoemulsification group (P = 0.083). Reoperations were four anterior chamber washouts and cortical material aspiration, one wound exploration due to leakage, and one IOL relocation. These six eyes achieved a CDVA of ≥6/7.5 (20/25) after the re-intervention; therefore, the final comparison between groups in terms of visual acuity was not affected.


  Discussion Top


In developed countries, phacoemulsification remains the preferred method for cataract surgery over mSICS, even though publications have shown comparable results between both techniques[3],[4],[8],[12] and costs of mSICS being considerably lower.[8],[13] Due to low rates and predictability of surgically-induced astigmatism, phacoemulsification is preferred for the correction of astigmatism during cataract surgery with toric IOLs, and for the same reason, it is used for the correction of presbyopia with multifocal IOLs turning cataract surgery into refractive cataract surgery.

In our study, both phacoemulsification and mSICS achieved excellent visual outcomes. Our mSICS results for both UDVA and CDVA are slightly better than previously reported series.[5],[14] These differences might be due to our exclusion criteria of patients with other ocular conditions (those studies did not exclude these eyes); besides, every eye in our series had ≤1.00 D of preoperative keratometric astigmatism. The World Health Organization defines visual impairment as vision worse than 6/18 (20/60 Snellen).[15],[16] Using this definition allowed us to compare our results with other publications. With the use of this standard, both techniques were extremely successful at restoring functional vision (CDVA ≥20/60 in 100% of mSICS and 98.6% of phacoemulsification), and both surgical methods were successful at achieving UDVA ≥20/60 (89.7% in mSICS group and 95.7% in phacoemulsification group). Our findings are comparable to previous studies of Ruit et al. (89% in mSICS and 85% in phacoemulsification at 6-month follow-up)[8] and Gogate et al. (71% in mSICS and 81% in phacoemulsification at 6-week follow-up).[4]

Although the difference in residual refractive astigmatism between the two groups was small, it was statistically significant in favor of phacoemulsification. Astigmatism induced by the 6.0–6.5 mm scleral tunnel may play a role in UDVA for the mSICS group being slightly inferior even though median refractive astigmatism in this group was reduced by 0.25 D. Recently, the trend in cataract surgery is shifting toward targeting ≤0.50 D of residual postoperative astigmatism to achieve optimum visual function and patient satisfaction.[17]

Surgically induced astigmatism in our mSICS group was lower than that reported in previous studies.[4],[7] This was achieved and optimized by making the incision according to the axis of the steepest keratometry,[17] resulting in less induced astigmatism, less postoperative refractive astigmatism, and better uncorrected visual acuities.[8],[18],[19]

In this study, refractive accuracy was also similar for both groups; SE was ± 1.00 D from the intended target in 88% of mSICS and 96% of phacoemulsification.

Both groups had a low intraoperative complication rate, with only one case of PCR with vitreous loss in the phacoemulsification group. However, there were six cases of postoperative complications that needed further surgical intervention, all in the mSICS cohort. No eyes lost ≥2 lines of CDVA in the mSICS group and two eyes in the phacoemulsification group lost ≥2 lines of CDVA; one was the eye with PCR and vitreous loss, and the other eye had mild chronic corneal edema.

This study is not free of limitations. They are as follows: retrospective design, sample size, and restricted follow-up limited the statistical power of the results. As we collected data from a single-center facility and because missing data were handled with available data method, some selection bias could be present (if missing pattern was not completely random, however, missing data were less than 3%). Data were analyzed for changes in each intervened eye over time, and although paired analyses were used, unmeasured confounding could exist. Other limitations of our study include that postoperative astigmatism was not measured by corneal tomography; therefore, vector analysis was not performed. Phacoemulsification was performed through a 3.2-mm limbal incision, and currently, this type of surgery is performed with smaller incisions, this could affect postoperative refractive astigmatism in this group. We believe that further studies, including a bigger sample size and randomized blind interventions, should be performed to allow adjustment for other confounders and draw causal conclusions.


  Conclusions Top


In summary, in the hands of experienced surgeons, phacoemulsification and mSICS produce comparable, excellent visual outcomes, with comparable low complication and re-intervention rates in patients with cataract. Prospective, multicenter studies are encouraged to further ascertain whether visual outcomes and safety profiles are comparable between mSICS and phacoemulsification and to ascertain potential cost-effectiveness differences between these techniques.

Acknowledgments

Mónica Paola Sandoval Ruballos, MD. provided assistance with English-language editing and with statistical analysis.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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Haripriya A, Chang DF, Reena M, Shekhar M. Complication rates of phacoemulsification and manual small-incision cataract surgery at Aravind Eye Hospital. J Cataract Refract Surg 2012;38:1360-9.  Back to cited text no. 3
    
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Gogate PM, Kulkarni SR, Krishnaiah S, Deshpande RD, Joshi SA, Palimkar A, et al. Safety and efficacy of phacoemulsification compared with manual small-incision cataract surgery by a randomized controlled clinical trial: Six-week results. Ophthalmology 2005;112:869-74.  Back to cited text no. 4
    
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Venkatesh R, Muralikrishnan R, Balent LC, Prakash SK, Prajna NV. Outcomes of high volume cataract surgeries in a developing country. Br J Ophthalmol 2005;89:1079-83.  Back to cited text no. 5
    
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Waghmare RR, Shinde CA, Shirwadkar S. A comparative study of pre- and post-operative refractive errors in cataract surgery-phacoemulsification vs. manual SICS in a tertiary care hospital. J Evid Based Med Healthc 2019;6:3211-5.  Back to cited text no. 7
    
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Ruit S, Tabin G, Chang D, Bajracharya L, Kline DC, Richheimer W, et al. A prospective randomized clinical trial of phacoemulsification vs. manual sutureless small-incision extracapsular cataract surgery in Nepal. Am J Ophthalmol 2007;143:32-8.  Back to cited text no. 8
    
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