|Year : 2022 | Volume
| Issue : 3 | Page : 326-330
Twelve month outcome of manual small-incision cataract surgery in Assiut, Egypt: A retrospective study with a large sample size
Mohamed Shehata, Mohamed Omar M. Aly, Mohamed Gamal A. Saleh, Mahmoud Abdel-Radi
Department of Ophthalmology, Assiut University, Assiut, Egypt
|Date of Submission||01-Jan-2022|
|Date of Decision||11-Jun-2022|
|Date of Acceptance||04-Jul-2022|
|Date of Web Publication||02-Nov-2022|
Department of Ophthalmology, 6th Floor, Assiut University Hospital, Assiut University, Assiut
Source of Support: None, Conflict of Interest: None
| Abstract|| |
BACKGROUND: To assess the visual outcome of manual small-incision cataract surgery (MSICS) as well as safety, cost, and time of the procedure.
PATIENTS AND METHODS: A retrospective study involving candidates for cataract surgery with baseline-corrected distance visual acuity (CDVA) ≤20/120. Visual acuity (VA) was the primary outcome measure while surgical complications, cost, and time of surgery were the secondary outcome measures. Follow-up visits were scheduled at 1 day, 1 week, 1 month, and at 6 and 12 months following surgery.
RESULTS: The study enrolled 3007 patients with a mean age of 66.45 ± 17.3 years. Out of 3007 patients, 2774 (92.2%) were legally blind before surgery (CDVA <20/200) which was significantly reduced to 55 patients (1.9%) by 1 month following surgery. Uncorrected distance visual acuity was 20/60 or better in 2098 eyes (69.8%) at 1 month, in 2035 eyes (67.7%) at 6 months, and in 2017 eyes (67.1%) at 12 months. The posterior capsular rupture was the most common intraoperative complication. Corneal edema was the most common immediate postoperative complication while the development of posterior capsular opacification was the leading cause for later impaired VA. The mean cost was approximately equivalent to 20 US dollars. The median duration of surgery was 10 min.
CONCLUSION: MSICS is a safe, cost-effective, and time-saving technique for improving the vision of cataract patients in areas with high cataract surgery volume and limited facilities.
Keywords: Egypt, manual small-incision cataract surgery, small-incision cataract surgery
|How to cite this article:|
Shehata M, M. Aly MO, A. Saleh MG, Abdel-Radi M. Twelve month outcome of manual small-incision cataract surgery in Assiut, Egypt: A retrospective study with a large sample size. Oman J Ophthalmol 2022;15:326-30
|How to cite this URL:|
Shehata M, M. Aly MO, A. Saleh MG, Abdel-Radi M. Twelve month outcome of manual small-incision cataract surgery in Assiut, Egypt: A retrospective study with a large sample size. Oman J Ophthalmol [serial online] 2022 [cited 2022 Dec 2];15:326-30. Available from: https://www.ojoonline.org/text.asp?2022/15/3/326/360389
| Introduction|| |
Cataract remains one of the major blinding diseases worldwide. To reduce the backlog or waiting list of cataract patients, the rates of cataract surgery should be, at least, equal to the incidence of new cases.
Poor outcomes of surgery adversely affect the perception of cataract surgery by the community. In the hope to eliminate unnecessary cataract blindness, effort to provide cataract surgery services has to be sustainable with continuous availability of adequate resources. To achieve this, the cost of cataract surgery should be made lower without jeopardizing surgery outcomes.
Before the era of phacoemulsification, extracapsular cataract extraction (ECCE) was the technique of choice for cataract removal. Later on, a randomized trial in the United Kingdom found phacoemulsification to be more effective than and economically comparable to conventional ECCE.
Manual small-incision cataract surgery (MSICS) involves removing the cataract through a 6-mm scleral tunnel without the use of phaco machines and usually the tunnel is self-sealing and does not need sutures. Compared with phacoemulsification, MSICS was found to be equally safe and effective with significantly lower cost, shorter operation time, and easier practicing transition from ECCE.,
The aim of the current study was to assess the visual outcome of MSICS as well as safety, time, and cost of the procedure in Assiut, Egypt, over a 1-year follow-up in a retrospective study with a large sample size.
| Patients and Methods|| |
A fully informed consent was obtained from each patient concerning the aim, possible benefits and complications of the MSICS procedure, and signed a written informed consent. The study was conducted under the tenets of the Declaration of Helsinki and after approval of the Ethical Committee of the Faculty of Medicine (IRB: 17300718).
This is a retrospective study of patients who underwent MSICS in a tertiary referral center between June 2015 and August 2019 where 3007 patients were included in the study.
Patients with age-related cataract as a primary cause of visual impairment with corrected distance visual acuity (CDVA) ≤20/120 were included in the study. Patients who had coexisting ocular or systemic diseases such as glaucoma, corneal opacities, dystrophies, ocular surface disease, retinal or optic nerve pathologies, poorly dilating pupils, and patients with uncontrolled diabetes or autoimmune diseases were excluded from the study.
Standard clinical examination included visual acuity (VA) testing with Snellen chart of uncorrected and corrected distance visual acuity (UDVA) and CDVA, slit-lamp biomicroscopy, and fundus examination. B-scan ultrasonography was done if the cataract precluded a good fundus view.
Keratometry readings were recorded before surgery if possible using the automated refractometer-keratometer (Huvitz HRK-7000 A-Korea republic). IOL power was calculated according to contact A-scan biometry and the Holladay 2 formula was the standard formula used in different axial lengths with emmetropia as a targeted refraction in all cases.
Retrobulbar anesthetic block was administered (2 ml of 0.02% lidocaine and 1 ml of marcaine) using a 25 gauge needle. A trained assistant prepared the eye for surgery by prepping of the surgical field and placing a sterile drape. Then, a superior rectus suture was placed followed by fashioning a fornix-based conjunctival flap at the 12 o'clock position, and cauterizing small bleeders. A bevel-up crescent blade was used for making a frown incision and creation of sclerocorneal tunnel. Opening of the anterior chamber (AC) by a keratome was then done with sideway motion to make a wider internal opening of the tunnel. The central frown incision was at least 2 mm behind the limbus and the external width of the incision was 6–8 mm according to the expected size of the nucleus
After performing continuous curvilinear capsulorhexis and hydrodissection with no hydrodelineation, a viscoelastic was injected both behind and in front of the nucleus into the AC. The fishhook technique was used to engage the nucleus with a bent cystitome within the capsular bag. The nucleus was then extracted through the sclerocorneal tunnel using gentle traction. The remaining cortex was aspirated using a Simcoe cannula.
A single piece polymethyl methacrylate posterior chamber was inserted into the capsular bag, and the remaining anterior capsule was removed with a Simcoe cannula. The conjunctiva was closed by grasping the two wound edges with the tips of bipolar diathermy probe. Postoperative treatment included moxifloxacin 0.5% eye drops five times daily, prednisolone acetate 1% eye drops four times daily for 3 weeks, and oral ciprofloxacin 750 mg once daily for a week.
All surgeries were performed by a single experienced ophthalmologic surgeon (M.S).
VA testing using Snellen's acuity chart, keratometry, and refraction using the same automated refractometer-keratometer were reported at 1 month, 6 months, and 12 months after surgery. The 1st-week postoperative measurements were not analyzed to allow for stability of refraction and visual outcome.
Data were analyzed using the Statistical Package for the Social Science (SPSS, version 20.0, IBM Corp., Armonk, New York, USA). The level of significance was considered at P < 0.05.
| Results|| |
The study enrolled 3880 eyes of 3880 patients who underwent unilateral MSICS, of whom 3007 patients completed their follow-up, while 873 patients were lost to follow-up and excluded from the study. Preoperative data are illustrated in [Table 1].
In our study, 2774 patients (92.2%) were legally blind with CDVA <20/200 before surgery which was significantly reduced to 55 patients (1.9%) 1 month following surgery (Chi-square test, P = 0.0006).
UDVA of 20/60 or better was achieved in 2098 eyes (69.8%) at 1 month and in 2035 eyes (67.7%) at 6-month follow-up. At 12 months, 2017 eyes (67.1%) had 20/60 UDVA or better which was not significantly different from the proportion achieving 20/60 unaided at 6 months (Chi-square test, P = 0.27).
There was no significant change in the proportion of eyes achieving a CDVA of 20/60 or better at 6 months (2825 eyes/94%) and 12 months (2803 eyes/93.2%) (Chi-square test, P = 0.87). Poor visual outcome (CDVA <20/200) was reported in 62 eyes (2%) at 6 months and 60 eyes (1.9%) at 12 months.
There was no significant change in mean manifest refractive spherical equivalent (MRSE) at 1 month, 6 months, and 12 months following surgery (One-way repeated measures ANOVA test, P = 0.93).
The visual and refractive outcomes at 1 month, 6 months, and 12 months after MSICS are summarized in [Table 2].
|Table 2: Postoperative visual outcome at 1 month, 6 months, and 12 months following manual small-incision cataract surgery|
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Measurement of corneal astigmatism by automated keratometry preoperatively was feasible in 1847 eyes (61.4%). In the remaining eyes, patients were unable to fixate on the target in the automated keratometer due to low VA caused by dense cataracts. In those patients, K readings were obtained from the other eye for biometry but not included in the statistical analysis. Out of 1847 eyes, 1048 eyes (56.7%) had against the rule of astigmatism. The mean preoperative keratometric astigmatism value was 2.64 ± 1.30 diopter (D).
Keratometry was carried out 1 month after surgery in the same 1847 eyes with preoperative recorded keratometry readings and the induced astigmatism was calculated using the Holladay method where 1633 eyes (88.4%) had against the rule astigmatism with a mean corneal astigmatism value of 4.74 ± 2.1D.
On comparing the mean keratometry readings preoperatively and 1 month following surgery, the mean change in corneal astigmatism score was 2.18 ± 1.21 (Wilcoxon signed-rank test, P = 0.01).
The induced astigmatism was >2D in 372 eyes (20.1%) and <1D in 594 (32.2%), and between 1 and 2 D in 881 (47.7%).
A summary of the encountered intraoperative complications is illustrated in [Table 3].
|Table 3: Reported intraoperative complications during manual small incision cataract surgery|
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[Table 4] summarizes the reported postoperative complications encountered after MSICS in our study.
|Table 4: Reported postoperative complications following manual small-incision cataract surgery|
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Cost and time
The mean cost per cataract operation was nearly 20 US dollars based on exchange rates in Egypt 2019. The median duration of surgery was 10 min.
| Discussion|| |
Sutureless cataract surgery is more technically demanding than conventional ECCE but it is less expensive because no sutures are required.
Our study reported that 69.8% of eyes achieved UDVA of 20/60 or better at the 1st-postoperative month and slightly decreased to 67.1% at the end of the follow-up (12 months) which was attributed mainly to the development of posterior capsular opacification in some eyes.
A similar study of sutureless MSICS in Nepal showed that only 58.3% of eyes obtained an uncorrected vision of 20/60 or better at 8 weeks. Early postoperative corneal edema in their study was encountered frequently during the development of the described technique.
Our results are comparable to Sherwin et al. who reported that 78.7% of 1145 eyes enrolled in their MSICS study had UDVA of 20/60 or better. On the other hand, our results are inconsistent with a similar retrospective study in Ethiopia conducted by Hussen et al. who reported a much lower percentage of eyes (nearly 25%) who achieved UDVA of 20/60 or better after MSICS. They explained their suboptimal visual outcomes by the retrospective nature of their study in addition to the fact that two-thirds of the study participants had their follow-up visits between the 1st and 4th week following surgery and were lost to follow-up.
At 1 month following surgery, the mean MRSE in our patients was −2.13D compared to −0.73D and −0.93D in the right and left eyes, respectively, in a study by Mengistu et al. but their sample size was much smaller than ours (90 eyes compared to 3007). However, our results showed stability of the postoperative mean MRSE with insignificant change at all follow-up visits.
Our results showed a statistically significant increase in postoperative compared with preoperative corneal astigmatism with concomitant increase in the percentage of patients having against the rule astigmatism. This could be attributed to the superior approach MSICS as advocated by Arthur et al. Refinements in the surgical technique by experienced surgeons could help to reduce postoperative astigmatism such as placing the outer incision of the sclerocorneal tunnel as far behind the limbus as possible and changing the site of the incision to a temporal tunnel incision to reduce the expected postoperative against the rule astigmatic shift.,
In the current study, the incidence of posterior capsule rupture was 1.3% which is comparable to Bhatta et al. with posterior capsular rupture rates of 1.78% during both high- and low-volume MSICS. Higher rates of posterior capsule rupture were recorded in other studies as a result of the steep learning curve of the new technique. Corneal edema was the most common immediate postoperative complication in our patients and in other studies. Endothelial damage can be minimized by nucleus extraction from within the capsular bag rather than displacing the nucleus into the AC and the generous use of dispersive viscoelastic material.
The average cost of a single MSICS in our study was nearly 20 dollars (2019 rates) which is relatively economic for most of the patients and cost-effective as described by other studies.
The average time for conclusion of surgery was 10 min which is also time-saving in high-volume MSICS in developing world as suggested by Ruit et al.
Systematic literature reviews suggested that MSICS has been refined over recent decades with overall outcomes comparable to phacoemulsification in certain settings. MSICS cost and visual outcome quality support its ongoing essential role in addressing global cataract blindness.,
| Conclusion|| |
MSICS is a safe, cost-effective, and time-saving technique for improving the vision of cataract patients in areas with high cataract surgery volume and limited facilities. Further studies are needed to assess the impact of possible modifications in the surgical technique to reduce the incidence of intra- and postoperative complications.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]