Cataract remains the principal cause of blindness in India and worldwide [1-3]. Rapid assessment surveys across Indian districts confirmed that most blindness in people aged 50 years and above is due to cataract and is therefore avoidable [2]. The number of operations performed in India has risen steeply, but the quality of the result matters as much as the number. Population and camp-based studies showed that a substantial proportion of operated eyes still had a poor visual outcome, mainly because of surgical complications, ocular comorbidity and uncorrected refractive error [4,5]. The World Health Organization therefore recommends routine monitoring of visual outcome after cataract surgery, and outcome monitoring has been adopted as a quality tool in many eye units [6,7].

Large trials in South Asia established the benefit of intraocular lens implantation over aphakic correction [8]. Extracapsular surgery with a posterior chamber lens then became the standard, and sutureless manual techniques were developed in which the nucleus is delivered through a self-sealing scleral tunnel. These techniques gave good results in high-volume programmes in Nepal and India [9-11] at a fraction of the cost of phacoemulsification [12]. Phacoemulsification is the standard technique in high-income countries and has produced excellent results in national audits [13,14], but it requires costly equipment and consumables and has a long learning curve.

Randomised trials from western India and Nepal found that manual small incision cataract surgery (MSICS) was safer and gave better uncorrected vision than conventional extracapsular surgery [15], and that it gave visual results close to those of phacoemulsification [16,17]. A Cochrane review summarised the trial evidence on these techniques [18]. Most of these data came from specialised high-volume eye hospitals. Less is known about the performance of the two techniques in rural medical college hospitals, where both are performed by teaching faculty and many patients present with advanced cataract. The aim of this study was to compare the visual outcome, complications, surgically induced astigmatism and operating time of MSICS and phacoemulsification at a tertiary care hospital in rural Maharashtra.

Study design and setting This prospective comparative study was conducted in the Department of Ophthalmology, Pravara Institute of Medical Sciences, Loni, a tertiary care teaching hospital serving a predominantly rural population. Written informed consent was obtained from every patient before surgery. Participants Patients aged 40 years or more with visually significant, uncomplicated age-related cataract who were fit for surgery under local anaesthesia were included. Patients were excluded if they had corneal opacity or endothelial dystrophy, glaucoma, uveitis, pseudoexfoliation, subluxated or traumatic cataract, diabetic or other retinopathy, macular disease, previous intraocular surgery, or only one functional eye. Eyes with pseudoexfoliation were excluded because mature cataract in such eyes carries a higher risk of capsular complications during manual surgery [19]. Sample size Assuming a standard deviation of surgically induced astigmatism of 0.75 D, 55 eyes per group were required to detect a difference of 0.4 D between the techniques with 80% power at a 5% significance level. Sixty eyes were included in each group, giving a total of 120 eyes of 120 patients. Preoperative evaluation All patients underwent recording of uncorrected and best corrected visual acuity on a Snellen chart, slit lamp examination, grading of nuclear hardness, applanation tonometry and dilated fundus examination where the media allowed. Keratometry and A-scan biometry were performed, and intraocular lens power was calculated with the SRK II formula. Blood sugar and blood pressure were checked before surgery. Surgical technique All operations were performed under peribulbar anaesthesia by experienced surgeons. In MSICS, a fornix-based conjunctival flap was raised superiorly and a 6.0 to 6.5 mm frown-shaped scleral incision was made about 1.5 to 2 mm behind the limbus [20]. A sclerocorneal tunnel was dissected 1 to 1.5 mm into clear cornea with a crescent knife and entered with a keratome to create a self-sealing internal valve [21]. After a side port incision and capsulotomy (capsulorhexis, or can-opener capsulotomy with trypan blue staining in white cataracts), hydrodissection was done and the nucleus was prolapsed into the anterior chamber and delivered with an irrigating vectis or with the anterior chamber maintainer technique [22]. Cortex was removed with a Simcoe cannula and a rigid polymethyl methacrylate posterior chamber lens was placed in the bag. The tunnel was left sutureless. In phacoemulsification, a 2.8 mm clear corneal incision was made, followed by continuous curvilinear capsulorhexis and hydrodissection. The nucleus was emulsified by a divide-and-conquer or chop technique, cortex was removed by automated irrigation and aspiration, and a foldable posterior chamber lens was implanted in the bag. All patients received topical antibiotic and corticosteroid drops, tapered over 6 weeks. Follow-up and outcome measures Patients were examined on the first postoperative day, at 1 week and at 6 weeks. At each visit uncorrected visual acuity, slit lamp findings and intraocular pressure were recorded. Best corrected visual acuity, keratometry and dilated fundus examination were done at 6 weeks. Visual acuity was classified according to World Health Organization categories as good (6/6 to 6/18), borderline (worse than 6/18 to 6/60) or poor (worse than 6/60) [6]. Surgically induced astigmatism was calculated from preoperative and 6-week keratometry by vector analysis. Intraoperative complications (premature entry, tunnel buttonholing, iris prolapse, Descemet membrane detachment, posterior capsule rupture, vitreous loss, zonular dialysis and nucleus drop) and postoperative complications (corneal oedema, raised intraocular pressure, anterior uveitis, intraocular lens decentration and endophthalmitis) were recorded. Operating time was measured from the first incision to the end of surgery. The primary outcome was the proportion of eyes with uncorrected visual acuity of 6/18 or better at 6 weeks. Secondary outcomes were best corrected visual acuity, intraoperative and postoperative complications, surgically induced astigmatism and operating time. Statistical analysis Data were entered in Microsoft Excel and analysed with Python version 3.13 using the SciPy and statsmodels libraries. Categorical variables were expressed as number and percentage and compared with the chi-square test, or the Fisher exact test when any expected cell count was below 5. Continuous variables were expressed as mean and standard deviation and compared with the independent t-test. A p-value below 0.05 was considered significant.

A total of 120 eyes of 120 patients were studied: 60 underwent MSICS and 60 phacoemulsification, and all completed the 6-week follow-up. The mean age was 64.4 ± 11.2 years, and 65 (54.2%) were men. The two groups were similar in age, sex, type of cataract, nuclear grade, preoperative visual acuity and preoperative astigmatism (Table 1).

Table 1. Baseline characteristics

MSICS: manual small incision cataract surgery; SD: standard deviation; D: dioptre. Chi-square or Fisher exact test for proportions; independent t-test for means.

Uncorrected visual acuity was 6/18 or better in 56.7% of eyes after MSICS and 68.3% after phacoemulsification on day 1 (p = 0.187), and in 63.3% and 88.3% at 6 weeks (p = 0.001). Best corrected visual acuity at 6 weeks was 6/18 or better in 83.3% and 98.3% of eyes respectively (p = 0.004). Borderline best corrected vision remained in 10 eyes after MSICS and 1 eye after phacoemulsification, and no eye had a poor outcome with best correction (Table 2).

Table 2. Visual outcome by World Health Organization category

Categories as recommended by the World Health Organization [6]. p-value from the chi-square test across categories at each visit.

Intraoperative complications occurred in 10 eyes (16.7%) in the MSICS group and 7 eyes (11.7%) in the phacoemulsification group (p = 0.432). Premature entry or buttonholing of the tunnel occurred in 4 eyes in the MSICS group. Posterior capsule rupture occurred in 2 eyes (3.3%) and 1 eye (1.7%) respectively, without vitreous loss or nucleus drop (Table 3). Early postoperative complications occurred in 16 eyes (26.7%) and 13 eyes (21.7%) (p = 0.522); the most common was corneal oedema on the first day, seen in 10 and 8 eyes respectively. No eye developed endophthalmitis (Table 4).

Table 3. Intraoperative complications

Chi-square or Fisher exact test.

Table 4. Postoperative complications

Chi-square or Fisher exact test.

Mean surgically induced astigmatism at 6 weeks was 1.26 ± 0.29 D after MSICS and 0.67 ± 0.30 D after phacoemulsification (p < 0.001). Mean operating time was 14.0 ± 3.3 minutes and 19.6 ± 3.1 minutes respectively (p < 0.001) (Table 5).

Table 5. Surgically induced astigmatism and operating time

Independent t-test.

In this prospective study from a rural tertiary care hospital, phacoemulsification gave better uncorrected and best corrected vision at 6 weeks than MSICS, and induced about half as much astigmatism. MSICS took on average 5.5 minutes less to perform, and the two techniques had similar rates of intraoperative and postoperative complications. Our findings are broadly consistent with the randomised trials from India and Nepal. Gogate and colleagues found that both phacoemulsification and MSICS were safe and effective, with low complication rates, at 6 weeks [16]. Ruit and colleagues reported excellent visual outcomes with both techniques and concluded that MSICS was faster, less expensive and less dependent on technology [17]. In our study, 98.3% of eyes after phacoemulsification and 83.3% after MSICS achieved best corrected vision of 6/18 or better. The phacoemulsification group thus met the World Health Organization recommendation that at least 90% of operated eyes should achieve good vision with correction, whereas the MSICS group fell short of it [6]. No eye in either group had a poor outcome. The trial evidence summarised in the Cochrane review supports the use of either technique when performed by trained surgeons [18]. The difference in uncorrected vision is largely explained by astigmatism. The larger scleral incision of MSICS induces more corneal shape change than a small clear corneal incision [23], and in our study mean surgically induced astigmatism was 1.26 D after MSICS compared with 0.67 D after phacoemulsification. The frown incision [20] and a temporal or superotemporal incision site [24] reduce surgically induced astigmatism in MSICS, and careful tunnel construction with a self-sealing internal valve [21] limits wound leak and astigmatic drift. Since all our MSICS incisions were superior, a temporal approach in eyes with pre-existing against-the-rule astigmatism could narrow the gap in uncorrected vision. The complication profile of the two techniques differed in type but not in overall frequency. Tunnel-related problems such as premature entry and buttonholing were seen only with MSICS, as expected [25], whereas zonular dialysis and Descemet membrane detachment were slightly more frequent with phacoemulsification. In the United Kingdom national audit, posterior capsule rupture occurred in about 2% of phacoemulsification operations [14]; in our study it occurred in 3.3% of eyes after MSICS and 1.7% after phacoemulsification, without vitreous loss or nucleus drop. Corneal oedema on the first day was common in both groups and resolved by 6 weeks. Corneal endothelial cell loss depends on the technique, the density of the nucleus and surgical trauma [26], and a randomised trial found no important difference in endothelial loss between MSICS and phacoemulsification [27]. No eye in our study developed endophthalmitis, and very low rates can be achieved with standardised sterilisation and prophylaxis protocols in high-volume settings [28]. Many patients in rural India present with mature or white cataract; about a quarter of the eyes in our study had mature cataract. In such eyes MSICS is safe and effective [29], and in a comparative study it gave visual outcomes similar to phacoemulsification while being faster and less expensive [30]. Mature cataracts in pseudoexfoliative eyes carry a higher risk of capsular complications [19], and these eyes were excluded from our study. The low cost of MSICS, which needs no phacoemulsification machine and few consumables [12], and its suitability for high-volume surgery [10,11] make it the more practical technique for outreach programmes, while phacoemulsification gives better and faster visual rehabilitation where resources allow. These findings have practical implications for teaching hospitals. Residents should be trained in MSICS as a core skill, both as a primary procedure and as a conversion option during difficult phacoemulsification, with attention to incision placement to reduce astigmatism. Routine monitoring of visual outcome, as recommended by the World Health Organization, helps units identify causes of borderline outcome and improve their results [6,7]. Strengths and limitations The strengths of this study are its prospective design, complete 6-week follow-up of all eyes, the comparison of both techniques in the same rural teaching hospital, and the use of standard World Health Organization outcome categories. It has limitations. Allocation was not randomised, and the operating surgeons could not be masked. The sample size was modest for rare complications. Follow-up was limited to 6 weeks, so late complications such as posterior capsule opacification and long-term astigmatic change were not assessed. Endothelial cell counts and patient-reported visual function were not measured.

Phacoemulsification gave better uncorrected and best corrected vision and less surgically induced astigmatism than MSICS at 6 weeks, with a similar rate of complications. MSICS was significantly faster, required less equipment and had no poor outcomes, and it remains a safe and practical technique for high-volume cataract surgery in rural India. Both techniques should be part of ophthalmology training, and attention to incision site and size can further improve the uncorrected visual outcome of MSICS.

DECLARATIONS

Acknowledgement: The author thanks the faculty, residents, nursing staff and operation theatre staff of the Department of Ophthalmology, Pravara Institute of Medical Sciences, Loni, and all the patients who took part in the study.

Funding: None.

Conflict of interest: The author declares no conflict of interest.

Author contribution: Dr. Shyam Popatrao Bawage designed the study, operated on and followed the patients, analysed the data, wrote the manuscript and approved the final version.

Data availability: The data supporting the findings of this study are available from the corresponding author on reasonable request.

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