Both retrospective and prospective studies have compared complication rates for phaco and MSICS. The three prospective studies comparing phaco and MSICS reported the incidence of posterior capsule rupture (PCR) with each of the two techniques (Table 3). In their study of white cataracts, Venkatesh et al. [32] reported that PCR occurred in 2.2 % of cases performed with phacoemulsification compared to 1.4 % of cases performed with MSICS; Ruit et al. [30] had a 1.85 % PCR rate with phacoemulsification compared to zero in the MSICS group. In a retrospective analysis of safety and efficacy of MSICS for brown and black cataracts, Venkatesh et al. encountered PCR in only 2 % of their cases. However, Gogate et al. [31] reported a slightly higher rate of PCR for MSICS (6 %) compared to phacoemulsification (3.5 %). It should be noted that all of the prospective trials had small study populations.

The largest and best comparative study to date was a retrospective study by Haripriya et al. [37], which analyzed 79,777 consecutive surgeries performed during a 1-year period at the Madurai Aravind Eye Hospital. Of these, 20,438 (26 %) were phaco, 53,603 (67 %) were MSICS, and 5736 (7 %) were large-incision ECCE. The overall rate of endophthalmitis was 0.04 % with no statistical difference between phaco and MSICS (Table 4). If performed by staff surgeons, both procedures had complication rates less than 1 %, suggesting comparable safety in the hands of experienced surgeons. However, for trainee surgeons (residents, fellows, and visiting surgeon fellows), the complication rate was significantly higher with phaco (4.8 %) than with MSICS (1.46 %) (P <0.001). For example, the trainee rate of posterior capsule rupture with vitreous loss was 3.8 % with phaco and 0.67 % with MSICS (P <0.001).

Posterior capsule opacification (PCO) occurred more often in the MSICS group compared to the phacoemulsification group in the Ruit study [30]. In that study, at the 6-month follow-up exam, 26.1 % of the MSICS patients compared to 14.6 % of the phaco patients had grade 1 PCO. The incidence of grade 2 PCO was 17.4 % in the MSICS group and zero in the phacoemulsification group. In this study, foldable IOLs with a square edge were employed in the phaco patients, compared to a rounded edge PMMA IOL in the MSICS patients, and only the phaco patients had a capsulorhexis.

Overall, complication and endophthalmitis rates appear to be similar between both procedures when performed by experienced surgeons. However, for inexperienced surgeons, MSICS appears to be the safer procedure.

Advanced and complicated cataracts are far more prevalent in poor populations. The literature reports good visual outcomes and complication rates when MSICS is employed for complicated cases, such as ultra-brunescent cataract [38], white cataracts [32, 39], and cataracts causing phacolytic and phacomorphic glaucoma [40, 41].

Finally, for a surgeon already experienced with manual large-incision ECCE, the learning curve for MSICS is shorter compared to that for learning phacoemulsification, which is more challenging to perform in advanced cataracts. Brunescent and mature cataracts increase the risk of posterior capsular rupture, dropped nuclei, and corneal decompensation. Therefore, an important consideration is that in many developing world settings, access to vitreoretinal or corneal transplantation surgery may be limited or completely lacking.

Another consideration in the developing world is the desirability of performing very high-volume surgery. In terms of mean procedural times, MSICS takes significantly less time than phacoemulsification (Table 5), even in the hands of very experienced surgeons. In their comparative trials, Ruit et al. [30] and Gogate et al. [31] reported identical mean surgical times (including turnover) of 15.5 min for phacoemulsification and 8.5–9 min for MSICS. Others have reported reducing mean surgical times to less than 4.5 min with MSICS [42, 43]. In the developing world, where care and procedures must be scalable to the highest volumes, improved surgical efficiency increases the productivity of the most critically scarce resource – the cataract surgeon.

In the developing world, the cost per case of providing phacoemulsification ranges from $25.55–$70, compared to $15–$17 for MSICS (Table 6). The wide variation in the cost of phacoemulsification relates to the varying case volumes, over which the fixed costs of expensive instrumentation are spread out. For example, Muralikrishnan et al. [44] reported a cost per case of $25.55 for phaco in a high-volume center in India. The IOL cost also significantly influences the overall cost per case. For instance, Ruit et al. [30] reported a cost of $70 for phacoemulsification of which $52 was the cost of the most expensive foldable acrylic IOL. In comparison, the cost of a PMMA lens used in MSICS was only $5. If a cheaper IOL was used instead of a foldable acrylic IOL, then the cost of phacoemulsification as estimated by Ruit et al. [30] should be in the $25 range as reported by Muralikrishnan et al. [44] and Gogate et al [45]. Compared to phaco, MSCIS clearly emerges as the more cost-effective option. Phaco entails a larger initial capital expense, higher per case consumable costs (phacoemulsification tips, sleeves, and tubing), and higher ongoing maintenance costs [44]. Another disadvantage of phacoemulsification for some rural developing world settings is the requirement for a dependable source of electricity. In contrast, the only significant capital equipment expense for MSICS is the operating microscope, and this can be powered by a battery or small diesel generator [44].