Clinical trial of manual small incision surgery and standard extracapsular surgery
Manual small incision cataract surgery (MSICS) is used increasingly for cataract extraction and intraocular lens implantation. It is thought that the small wound heals faster than a conventional incision, leading to less astigmatism and a better uncorrected visual acuity. This is important as many patients do not wear or cannot afford spectacles after surgery, which means that their uncorrected visual acuity is what they rely on to carry out their every day functions. Often this is less than 6/18 on the Snellen’s chart, which would fall below the WHO ‘good outcome’ category for post-operative visual impairment. A post-operative vision of 6/18 or better without spectacles is a goal which appears to be within the reach of small incision techniques for cataract surgery. However, there are concerns that the method used to remove the nucleus in MSICS may be more traumatic to the corneal endothelium than conventional ECCE surgery.
Irritation and infection from sutures, which necessitates their removal, are arguments against conventional ECCE/IOL surgery. This is particularly problematic in large community eye care programmes where the expertise and equipment for suture removal may not be available in remote villages and the number of visits to an eye centre may increase the costs. It seems likely that patients without sutures would be more comfortable, less likely to rub their eyes and more satisfied with surgery.
When changing from one technique to another, we also need to consider costs of surgery, both to the provider and to the patient. An operation that gives better results but which costs much more may lead to unequal opportunities as only the wealthy could afford the better surgery. These issues (i.e., visual outcome, quality of life, patient satisfaction and cost) have been studied in a randomised clinical trial to compare conventional ECCE/IOL surgery with MSICS / IOL surgery in Pune, India.1, 2 Key findings are summarised in this article.
The purpose of the trial was to compare MSICS with conventional ECCE in terms of safety, effectiveness, costs and quality of life. A total of 741 patients aged 40-90 years with operable cataract were randomly assigned to receive either MSICS or ECCE, and they were operated on by one of eight experienced surgeons. In ECCE, the cataract nucleus was removed through a 10mm limbal incision followed by cortex aspiration and posterior chamber IOL implantation. The wound was closed with 8-0 or 10-0 interrupted sutures. In MSICS, a scleral tunnel was constructed using a keratome and the lens nucleus delivered into the anterior chamber. It was then removed with visco-elastic. Cortex aspiration and lens implantation was similar to ECCE, but no sutures were needed as the wound was self-sealing. Patients were followed up at 1 week, 6 weeks, and 1 year after surgery when they were examined and had their visual acuity recorded before and after refraction.
Questionnaires developed for the Madurai intraocular lens implant study3 were used in the trial in Pune to compare patient satisfaction, vision function and quality of life. These questionnaires were designed for use in trials of cataract patients who were blind in both eyes.
To compare the cost of MSICS with conventional ECCE, the fixed facility and recurrent cost for the two procedures was calculated. Average cost per procedure was calculated by dividing the total cost by the number of procedures performed. The average personnel cost for a procedure was calculated using the time required to perform it. A stopwatch was used to measure the surgery time in minutes and seconds.
Safety and Effectiveness
The study found that MSICS gave an uncorrected visual acuity of 6/18 or better in a higher proportion of patients than ECCE at 6 weeks. Corrected visual acuities of 6/18 or better were also slightly higher in MSCIS, but this was not statistically significant. Poor outcomes (post-operative visual acuity of <6/60) was 1.7% in MSICS and 1.1% in ECCE at 6 weeks.
The rates of intra-operative and post-operative complications were similar in the two groups, except for transient post-operative corneal oedema which was more common following MSICS. However, by 6 weeks there was no difference between the two types of surgery.
This trial found MSICS to be marginally more economical than ECCE, and although the cost of keratome blades was high this was offset by savings on sutures.2 The cost of the fixed facility was the same for both the techniques ($11.34 for the service provider) and the consumable costs for MSICS was marginally less than for the conventional ECCE technique ($4.34 and $4.48 respectively). Surgical time was similar, with MSICS generally requiring less time as no suturing was required. The average surgical time for the eight surgeons using MSICS was 12 minutes (range: 6 min 19 sec – 27 min 25 sec) and for ECCE was 12½ minutes (range: 7 min – 25 min 40 sec). MSICS may work out to be cheaper in the long term because of fewer post-operative visits, fewer post-operative drugs and fewer patients needing spectacles.
Quality of Life
There was no significant difference between conventional ECCE and MSICS in the scores of visual function and quality of life. There was a small difference in the patient satisfaction scores, with MSICS scoring better.
The findings of this trial show that MSICS gives better short term visual results than standard ECCE, particularly before correction, without a higher rate of complications or adverse outcomes, and at a marginally lower cost. Concerns about endothelial damage were not substantiated clinically in this trial. A study in Madurai found endothelial cell loss to be only 6% following MSICS.4 Most problems in MSICS arise with very hard cataracts and small pupils,1 and ECCE may be an alternative in such cases.
Ultimately, the choice of technique of surgery for uncomplicated cataract depends on the type of cataract, the surgeon’s skills and available resources. Phacoemulsification provides excellent and immediate visual rehabilitation, but the cost of equipment, consumables and maintenance make it unaffordable in many settings. The majority of ophthalmologists in developing countries are being trained in conventional ECCE surgery. The change to MSICS is easier than learning phacoemulsification, as anterior chamber dynamics in MSICS are similar to conventional ECCE. More trials are needed to compare the different techniques and their variations, to provide better evidence of the costs and benefits.
1 Gogate P M, Deshpande M, Wormald R P, Deshpande R D, Kulkarni S R. Extracapsular cataract surgery compared with manual small incision cataract surgery in community eye care setting in Western India: a randomized controlled trial. Br J Ophthalmol 2003; 87: 667-672.
2 Gogate P M, Deshpande M, Wormald R P. Is manual small incision cataract surgery affordable in the developing countries? A cost comparison with extracapsular cataract extraction. Br J Ophthalmol 2003; 87: 843-846.
3 Fletcher A E, Selvaraj S, Vijaykumar V, Thulasiraj R D, Ellwein LB. The Madurai intraocular lens study III: Visual functioning and quality of life outcomes. Am J Ophthalmol 1998; 125: 26-35.
4 Natchiar G. Evaluation of MSICS (astigmatism and endothelial cell loss). In: Manual Small Incision Cataract Surgery. Madurai: Aravind Publications; 2000. p. 43-48.