Cataract

Risk factors

Although most cases of cataract are related to the ageing process, occasionally children can be born with the condition, or a cataract may develop after eye injuries, inflammation, and some other eye diseases.

The main non-modifiable risk factor for cataract is aging. Other frequently associated risk factors are trauma, uveitis, diabetes, ultraviolet light exposure, and smoking. Children are occasionally born with cataracts, mainly due to genetic disorders. Women are at greater risk than men for developing cataracts and are less likely to have access to services.

Impact

Cataract remains the leading cause of blindness and an important cause of visual impairment across the globe.

The Vision Loss Expert Group (VLEG) estimates that over 17 million people are bilaterally blind from cataract in the world in 2020, representing 40% of all global cases of blindness.

The proportion of blindness due to cataract among all eye diseases ranges from 15% in high income regions to 50% or more in poor and/or remote regions.

Treatment and successes

Cataract surgery, in which the lens is removed and replaced by an intra-ocular lens, restores sight and is considered a highly cost-effective intervention.

Cataract surgery can alleviate poverty. One year after cataract surgery, patients increase their productivity by an average of 1-2 hours per day, are more independent, and their per capita expenditure may increase to the levels of those who do not have visual impairment.

One ophthalmologist should be able to undertake as many as 2,000 or more cataract surgeries a year, provided that there are adequate support staff, infrastructure, and patients who are able and willing to access the facilities.

Techniques

There are three commonly employed surgical techniques for cataract removal:

• extracapsular cataract extraction
• phacoemulsification and
• small incision cataract surgery

In each of these techniques, the eye’s natural lens is removed during surgery. It is replaced by an artificial intra-ocular lenses implanted into the eye. Phacoemulsification is the standard of care in high-income countries and requires sophisticated equipment and more expensive intra-ocular lenses

Extracapsular cataract extraction (ECCE) is the traditional method, which involves a standard incision to remove the nucleus of the lens and cortex and insert an IOL. This technique requires removable sutures and a longer recovery period. The complication rate is also higher.

Phacoemulsification (phaco) uses an ultrasound probe is used to fragment the lens, which is aspirated through a small incision. A foldable IOL is insert through the incision, and in most cases, sutures are not necessary and patients can return to work and/or full productivity more quickly than with ECCE. Phaco is the preferred cataract surgical method in developed countries, but large-scale implementation of phaco is challenging in developing countries due to:

• the expense
• number of mature cataracts
• lack of trained surgeons and technicians.

Small incision cataract surgery (SICS) is a refined ECCE method, which may be an appropriate manual substitute to phaco in developing countries due to its lower cost, lesser technological requirements, its faster procedure, and comparable qualitative outcomes. Similar to phaco, a small incision and foldable IOL are used. There are also now low-cost, good quality IOLS available.

SICS usually does not require sutures and has a faster recovery period than conventional ECCE but costs a fraction of the cost of phaco surgery in developing countries. The average time of a SICS procedure is significantly less than that of phaco, but both procedures have comparable outcomes.

Quality of cataract surgery

According to the WHO, targets for the quality of cataract surgery will be met when at least 85% of operated eyes achieve a post-operative visual acuity of 6/18 or better. Good post-operative visual acuity is considered to be 6/6 – 6/18.

Quality assessment training is urgently needed to reduce the burden of unoperated cataract.

Trends and challenges

Despite the fact that cataract is easily treated and cataract surgery is considered one of the most cost-effective interventions, in many remote and poor areas of the developing world, people remain blind from cataract, mainly due to a lack of access to eye care. This is due to several reasons:

• The number of people with cataract grows as the world population ages.
• Significant barriers to cataract are lack of awareness, shortage of trained eye health personnel, limited accessibility, high cost of treatment, and poor surgical outcomes.
• Other limitations are lack of public health resources and political will to address cataract.
• The uptake of high-quality, low-cost cataract service models is slower in developing countries, due to the local influence of the private sector and the presence of more expensive products on the market.
• A recent ICO study found that the global ophthalmic population is decreasing 1.7% year compared to the population increasing aged ≥60 years.

A comprehensive strategy to cataract-service delivery is needed that integrates availability, affordability, accessibility, and acceptability of cataract care.