One in three of the world’s 32.4 million blind people (<3/60 presenting visual acuity (VA) in the better-seeing eye) are blind due to cataract, and this proportion is closer to one half in sub-Saharan Africa (SSA) [1, 2]. In addition, there are many millions more who have significant visual impairment from cataract. This is despite an effective, low-cost cure for cataract having been known for decades.
The availability of cataract surgical services in SSA is by no means universal, but even where services are available, uptake has mostly been below the level required for elimination of cataract blindness [3]. Cataract surgical rates (CSR) of around 500 operations/million population/annum are frequently reported, well below the target of 2000 that has been suggested by the World Health Organisation (WHO) [4, 5]. A commonly cited barrier to acceptance of surgery is concern about poor outcomes from surgery amongst potential beneficiaries [6,7,8,9].
The WHO defines the quality of outcomes as “good” if the vision is 6/18 or better and “poor” if it is <6/60. WHO outcome quality targets have been set of >80% “good” uncorrected outcome and/or 90% “good” best-corrected acuity, >4 week post-operatively and a maximum of 5% having a “poor” outcome [10]. Although large case series have been published from higher volume settings, demonstrating 79% “good” uncorrected outcomes (by a single surgeon doing >1455 adult cataracts per year) [11] and 89% best-corrected (in a unit doing >1800 cataracts per year) [12], to our knowledge, there are no published series of cataract cases from routine African hospital services that attain the WHO benchmarks. Rates of “poor” outcomes typically sit over 20% (range 14.6–44% from a review of case series) [13]. This is not the experience of the rest of the world, with recent international studies showing that the proportion of poor outcomes is a particular problem for SSA [14, 15].
If 20% of operated cataract cases fail to attain 6/60, it can be expected that this will generate some negative publicity in the general population that might then discourage uptake of surgery in an unhelpful feedback loop. Improving the quality of surgery on offer in SSA is therefore critical to the goal of increasing the quantity of surgery being performed and the reduction in cataract blindness.
There is an established link between the volume of surgery performed by a surgeon and the outcomes of surgery; the largest published study reported an eightfold increase in the complication rate for the least active surgeons (50–250 cataracts per year) when compared to the most active (>1000 cataracts per year) [16].
In grading systems of the quality of evidence, “expert opinion” is considered the poorest quality source (www.cebm.net/oxford-centre-evidence-based-medicine-levels-evidence-march-2009). However, where the evidence base is weak it may be the only option or at least offer a starting point to those wishing to further develop the evidence base.
To improve upon an unrefined “expert opinion”, the Delphi method provides a structured communication methodology that utilises a group of experts to predict or prioritise variables in an iterative process [17]. Its use in health care and research is increasing, and in the ophthalmic literature, it has been used to select clinical indicators for evaluation of disease progression and to guide selection of outcome measures by international research communities [18,19,20].
Given cataract’s pre-eminence as a global cause of blindness, there is a relative paucity of studies exploring interventions to improve outcomes in low- and middle-income countries. The purpose of this study was to generate consensus, using a Delphi process, around what factors might have the strongest influence on the outcomes of surgery and therefore form appropriate focuses for intervention.