Reading Material for the Prevention of Blindness Workshop



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Results

Data from the rapid assessments on the prevalence of cataract blindness and Cataract Surgical Coverage from Karnataka State are given in Table 1 and Table 2.
The number of persons with bilateral operable cataract increases from 1,157 to 3,345, depending upon the level of visual acuity, while the number of persons with bilateral aphakia remains the same. Similarly, the number of operable cataract eyes increases from 4,481 for VA<3/60 to 11,511 for VA<6/18, while the number of aphakic eyes remains the same.
A

Table 3: Cataract Surgical Coverage from Sample Data on Operable Cataract and Aphakia in Ahmedabad District (1997)

Category

Condition

VA<3/60

VA<6/60

VA<6/18

z

No. persons with bilateral operable cataract

26

69

206

y

No. persons bilaterally (pseudo)aphakic

292

292

292

x


No. persons one eye aphakic + one eye operable cataract

47

83

139

b*

No. operable cataract eyes*

158

310

689

a**

No. (pseudo)aphakic eyes**

776

776

776

%

first eyes: 62.4% (a-y)/a










%

second eyes: 37.6% y/a













Cataract Surgical Coverage (eyes) a/(a+b)

83.1%

71.5%

53.0%




Cataract Surgical Coverage (persons) (x+y)/(x+y+z)

92.9%

84.5%


76.7%

*b is defined as all eyes with cataract causing an acuity of less than 3/60, 6/60 or 6/18.

**a is defined as all eyes which are aphakic or (pseudo)aphakic, regardless of acuity.



t VA<3/60, 34.9% of all cataract blind eyes and 53.2% of all bilateral cataract blind persons have been operated upon, assuming that only people with cataract and a VA<3/60 were eligible. As expected, the coverage indicators for VA<6/60 and VA<6/18 are lower: 40.1% and 26.2% for persons and 26% and 17.3% for eyes respectively. Nearly 77% of all operations were performed in the first eye, and 23% in the second eye.

Table 2 gives the prevalence of bilateral cataract blindness, CSC(eyes) and CSC(persons) for each district and also by gender. One might expect that a district with a high surgical coverage would have a low prevalence. However, that is not always the case. Mandya District, for example, has a prevalence rate three times higher than Kodagu District, while the coverage indicators for persons and eyes are nearly the same. It can also be seen, from Table 2, that the prevalence of cataract blindness for females is nearly twice as high as for males. The differences in coverage are less marked .

Table 3 gives the results of the rapid assessment in Ahmedabad. Here the situation is different. There are many more persons with bilateral (pseudo)aphakia than with bilateral blindness, or severe visual impairment due to cataract. The number of (pseudo)aphakic eyes is 5 times higher than the number of cataract blind eyes. For operable cataract eyes (VA<6/60) it is more than twice as high and for VA<6/18 there are slightly more aphakic eyes than eyes with operable cataract. The Cataract Surgical Coverage is 92.9% for blind persons (VA<3/60) and 83.1% for eyes, assuming that only people with cataract and a VA<3/60 had been operated on. The Coverage of <6/60 is 84.5% for persons and 71.5% for eyes.

The coverage of visually impaired cataract (VA<6/18) is higher in Ahmedabad than in Karnataka, indicating that surgical intervention is being undertaken at an early stage of visual loss. More second eyes (37.6%) have been operated in Ahmedabad than Karnataka.
The problem of cataract blindness seems to be under control in Ahmedabad and the capacity to provide surgical services is sufficient to cater for the needs of most people in the district. Nevertheless, we still found 26 persons who were bilaterally blind (VA<3/60) from cataract in the sample. These patients were asked in the survey why they had not been operated on so far. Six patients mentioned ‘medical contra-indications’ and seven ‘no felt need’; the remaining patients a variety of other reasons. This may be the ‘hard core’ of the cataract problem - the patients who cannot or do not want to have surgery.




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