Cataract blindness in Turkmenistan
Reported, January 10, 2012
Age related cataract remains the major cause of visual impairment and blindness in developing countries. A declining birth rate and increased life expectancy resulted in a sharp increase in the number of people of 50 years and older. In many countries this has caused an increase in the prevalence of cataract blindness and a greater demand for adequate cataract surgical services.
Turkmenistan became independent from the former Soviet Union in 1991. The country is situated in the western part of central Asia, bordering the Caspian Sea in the west, Iran and Afghanistan in the south, Uzbekistan in the northeast, and Kazakhstan in the north. The Karakum desert occupies nearly 80% of its territory. Turkmenistan is divided into five administrative regions: Akhal (Ashgabad city, the capital), Mary (Mary city), Lebap (Turkmenabad city), Balkan (Balkanabad city), and Dashoguz (Dashoguz city). Each region consists of a large regional city, surrounded by little towns and settlements.
Ophthalmic services in Turkmenistan are only provided by the government. Private practice is not allowed. Besides the scientific clinical centre for eye diseases in the capital Ashgabat, with 120 beds, there are nine more eye departments with a total of 380 beds in general hospitals in regional cities. In the centre, 15 eye surgeons operate on cataract patients and another 20 surgeons work in the peripheral eye units. In the year 2000 they conducted a total of 2500 cataract operations, giving a cataract surgical rate (CSR) of 562. In 1990, 1711 cataract operations were performed and the CSR was estimated at 440.
Of all extracapsular cataract extractions, 60% are conducted in the centre in Ashgabat and 40% in the regional centres. In 1995 a special national health policy was introduced, focusing on the introduction of new technologies into health care, including in ophthalmology. From 1996 to 2000 the number of cataract operations in the centre increased from 869 to 1448 operations per year, an increase of 66%. The proportion of extracapsular extraction with IOL implantation rose from 45.5% to 76.2%.
A nationwide survey on blindness and visual impairment due to cataract was conducted in 20001. The findings from this survey provide baseline data for the cataract intervention activities and facilitate adequate planning and future monitoring of the programme.
A total of 6120 people aged 50 years were eligible for examination, out of which 6011 (98.2%) were physically examined: 2810 males and 3201 females. Nine people refused examination and another 100 remained absent, despite repeat visits. Information about the visual status of these 109 people was obtained from relatives or neighbours. Their data are not included in the analysis.
Out of the total 6011 examined people of 50 years and older 76 (1.26%) were bilaterally blind (VA <3/60 with available correction) due to all causes. From these, 32 people (42%) were bilateral blind due to cataract, giving a prevalence of 0.5%.Prevalence rates are for the 50+ age group.
The prevalence of blindness (due to cataract as well as other causes) increases by age and is usually higher in females. When the age and sex composition of the sample differs from the actual population of the survey area, the prevalence rates calculated from the sample data do not reflect the true prevalence in the population. When the age and sex composition of the population in the entire survey area is entered in the software package, it will adjust the sample results automatically to present the actual situation.
The age and sex adjusted prevalence of all bilateral blindness was 1.3% (95% CI: 1.0 to 1.7), an estimated total of 6196 people. Assuming that bilateral blindness under the age of 50 is negligible, this would be equal to a prevalence of 0.13% in the entire population, approximately 10% of the prevalence in the 50+ age group. The adjusted prevalence of bilateral cataract blindness is 0.6% (95% CI: 0.4 to 0.9), an estimated total of 2821 patients. In 45% of the patients cataract was the main cause of bilateral blindness. A total of 16 236 eyes are estimated to be blind due to cataract.
The prevalence of bilateral severe visual impairment due to cataract is more than four times higher: 2.6% (95% CI: 2.1 to 3.2), or 0.26% for the entire population, an estimated 12 161 patients. The prevalence of all VA <6/60 was 4.4% (95% CI: 3.8 to 5.2), or 0.44% of the entire population, an estimated 20 844 patients. In 58% of these patients cataract was the main cause of bilateral severe visual impairment.
After cataract, glaucoma is the second most common cause of bilateral blindness (25%), followed by posterior segment disorders (6.6%) and phthysis bulbi (5.3%). In case of severe visual impairment (VA <6/60) bilateral cataract is the major cause with 58%, with glaucoma as second. Cataract is more common in females, phthysis bulbi more common in males.
Patients blind or severely visually impaired due to cataract were asked why they had not been operated so far. Fatalism (old age, no need for surgery) was the main barrier, followed by waiting for maturity, fear of operation, and no company.
By comparing the number of (pseudo) aphakic people or eyes, with the number of cataract blind people or eyes, we can calculate the cataract surgical coverage, the proportion of the all cataract blind people or eyes, that have been provided surgical services, irrespective of the visual outcome.6 It can be calculated for various levels of blindness or visual impairment, for males and females. It indicates which part of the cataract problem has been covered so far and also gives an idea of the availability and accessibility of the cataract surgical services to the population of the survey area during the past period.
Of each four bilateral cataract blind people (VA <3/60), three have been operated in one or both eyes and one was not operated in either eye. Of all cataract blind eyes 57% have been operated on. The coverage was less for severe visual impairment (VA< 6/60) due to cataract: 44% of the patients with bilateral impairment were operated in one or both eyes and nearly 32% of the eyes were operated on.
Visual acuity was measured in all aphakic or pseudophakic eyes in the sample .This gives an impression of the visual outcome after cataract surgery. It is important to realise that these cases include patients operated recently as well as decades earlier, by skilled as well as less skilled surgeons under optimal as well as less optimal conditions. Good results from recent operations may be overshadowed by less successful practices from the past. Also, initial good outcome may have deteriorated because of concurrent sight threatening disorders, like age related macular degeneration, glaucoma, etc.
After IOL implantation 8.2% of the operated eyes could not see 6/60, against 44.8% of the cataract operations without IOL implantation. Poor outcome was mostly attributed to uncorrected aphakia (43%), concurrent eye diseases causing blindness (38%), and surgery related complications (19%). All patients were operated on in government hospitals only. Treatment was provided free of cost in 62% of cases. Another 38% paid part of the costs, mostly the cost of the IOL and some special investigations. Cost recovery schemes for cataract operations were introduced 34 years ago.
The age and sex adjusted prevalence for all bilateral blindness (VA <3/60) in the entire population of 0.13% is less than half of the WHO estimate of 0.3% for this region.7 The age and sex adjusted prevalence of bilateral cataract blindness in people of 50 years or older was 0.6% (95% CI: 0.4 to 0.9), less than a quarter of the estimated prevalence used in the design of the study. As a result the confidence intervals around the prevalence rates for VA <3/60 are far wider than anticipated.
The age and sex adjusted prevalence of bilateral cataract and VA<6/60 in the better eye is considerably higher: 2.6% (95% CI: 2.1 to 3.2). With a variation of 22% around the prevalence this is a fairly accurate estimate. An estimated 12 161 people have a VA less than 6/60 in the better eye due to cataract. A total of 46 650 eyes are severely visually impaired due to cataract.
The surgical coverage for VA <3/60 is fairly good with 75% of all bilateral cataract blind people and 57% of all cataract blind eyes having been operated. The coverage for VA <6/60 is considerable less, indicating that most eye surgeons use VA <3/60 as intake criteria for cataract surgery or have only recently lowered their threshold to VA <6/60. The fact that waiting for maturity was the second main barrier to cataract surgery may also support this.
The proportion of people of 50 years and older is relatively low with 9.94% of the total population, and hence fewer people are at risk for age related cataract. But these factors are not enough to explain the low prevalence of bilateral cataract blindness.
With 35 cataract surgeons (one eye surgeon per 135 000 people) and 500 dedicated beds there is potential to increase the annual output of cataract surgeries further above the current CSR of 500, an average of 71 cataract operations per surgeon per year. If each cataract surgeon could perform 285 surgeries in a year, the total annual output would be 10 000, a CSR of 2000. This would be in line with the recommendations given by the global initiative for the elimination of avoidable blindness.
To achieve this, the intake criteria for cataract surgery may have to be lowered from the current level of VA <3/60 to VA <6/60, and at a later stage perhaps even to VA <6/36. Awareness campaigns may have to be initiated to inform the public of the advantages of modern IOL surgery, that it can be done at an earlier stage, and that the results are better. Approximately 54% of the population is rural, living far away from the urban hospitals and surgical service. They rely on regional hospitals where the IOL surgery is not yet available. Of all cataract operations, 72% was on first eyes and 28% on second eyes, indicating that many patients seem to be satisfied with one operated eye only. There may be some indifference and lack of awareness by patients, since old age, no need for surgery was the main barrier for patients to have operations. However, the second major barrier, waiting for maturity, may indicate that some patients do request cataract surgery at an earlier stage but are told to wait. The recent introduction of family doctors may also help to create more awareness with the public and lead to timely referrals for cataract surgery.
From the visual outcome data it appears that not all surgeons have shifted to IOL surgery. The visual outcome of cataract operations without IOL needs to be further investigated to explain the high proportion of poor visual outcome. Uncorrected aphakia, which appeared as a major cause of poor outcome, is unnecessary and relatively easy to solve. Routine monitoring of visual outcome after cataract surgery could be introduced to improve results of future operations.
When lowering intake criteria for cataract surgery, IOL implantation is recommended because of the higher gains in visual functioning. However, care should be taken that all surgeons are adequately trained and their units are all provided with the necessary equipment for IOL surgery.
Credits:S Amansakhatov,Z P Volokhovskaya,A N Afanasyeva,and H Limburg
S Karanov Scientific Clinical Center for Eye Diseases Ashgabat, Turkmenistan & British Journal of Ophthalmology
More Information:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1771347/?tool=pubmed