2.3 Blindness

In this section, the numbers of blind people in the ROI are estimated using the data from the blind register and population forecasts described above, and published study data reporting the likely extent of under registration of blind people in the ROI.

2.3.1 Current prevalence rates

2.3.1.1 Total blindness

Estimates of age/gender specific prevalence rates were derived from the NCBI register data for 2010, as described above, and were applied to population estimates from the CSO (2008).

There were 10,223 registered blind people who met the blind criteria, in 2010. To account for under-registration of blind people in the ROI, an adjustment factor was derived from a study by Kelliher et al (2006), which was the only study identified that estimated the extent of under-registration. Kelliher et al (2006) conducted an additional 9-week study of a tertiary referral ophthalmology department in the ROI and ascertained the registration status of all eligible patients. Over the study period, 75 of 2,320 attending outpatients (3.2%) fulfilled the blind registration criteria, and 16 of 75 (21.3%) had not been appropriately registered. This implies that the number of people who are actually blind is 27.1% greater than the number who are registered i.e. 1 ÷ (1 – 0.213) = 1.271. Therefore, an adjustment factor for under-registration of 1.271 was applied in this study.

It should be noted that many people with deteriorating vision do not seek advice from health care professionals and consequently are never referred to hospital for their vision loss. Therefore, the adjustment factor estimated from hospital data is likely to be conservative (Kelliher et al 2006), and the resulting prevalence rates of mild and moderate VI, which are estimated from blindness prevalence (see below), are also likely to be conservative.

This adjustment factor applied to total registered people gives an estimate of 12,995 (1.27 × 10,223) blind people in the ROI in 2010. This represents a total blindness prevalence rate of approximately 0.28% when divided by the total population of the ROI in 2010 (4,591,784 people from Table 2.1 in Section 2.1).

The derived age-gender prevalence rates for blindness are presented in Table 2.3. Please refer to the audio files to listen to the table or to the PDF to view the table. These were estimated by multiplying the number of people on the NCBI register by the adjustment factor for under-reporting, and dividing this number by the population size of that group in the ROI in 2010 (see Table 2.1 in Section 2.1). A rising age-distribution for blindness prevalence is apparent, and the total prevalence of blindness is higher for females than for males.

Table 2.3: Prevalence rates for blindness(a) in the ROI, by age and gender(b)

Age group	Male	Female	Total
0-4	0.025%	0.031%	0.028%
5-9	0.051%	0.045%	0.048%
10-14	0.096%	0.086%	0.091%
15-19	0.099%	0.091%	0.095%
20-24	0.103%	0.102%	0.102%
25-29	0.088%	0.090%	0.089%
30-34	0.104%	0.104%	0.104%
35-39	0.129%	0.122%	0.126%
40-44	0.145%	0.157%	0.151%
45-49	0.171%	0.164%	0.168%
50-54	0.202%	0.197%	0.200%
55-59	0.247%	0.255%	0.251%
60-64	0.320%	0.265%	0.293%
65-69	0.418%	0.346%	0.382%
70-74	0.623%	0.584%	0.603%
75-79	1.074%	1.125%	1.102%
80-84	2.300%	2.303%	2.302%
85-89	4.185%	4.718%	4.533%
90+	12.034%	10.905%	11.221%

Source: Deloitte Access Economics estimates using NCBI register data (special request, 2010), ROI population estimates (CSO, 2008) and Kelliher et al (2006)

(a) Blindness defined as VA <6/60 in better eye or central visual field ≤ 20 degrees.

(b) Total people on NCBI register in 2010 adjusted upwards by 1.27 adjustment factor to account for under-registration (Kelliher et al, 2006).

2.3.1.2 Blindness by cause

Derived age-gender prevalence rates of blindness by cause of blindness are presented in Table 2.4. These were calculated by applying the age-gender specific cause distributions from the NCBI register data to the prevalence rates in Table 2.2. Please refer to the audio files to listen to the table or to the PDF to view the table.

2.3.2 Population estimates and projections

2.3.2.1 Estimates by age and gender

Blindness prevalence rates were applied to population projections from the CSO (2008) to estimate future numbers of blind people in the ROI. Estimates of the numbers of blind people in the ROI are presented by age-gender group in Table 2.5. Please refer to the audio files to listen to the table or to the PDF to view the table. It is estimated that there were nearly 13,000 blind people in the ROI in 2010, which is expected to grow to nearly 18,000 people by 2020.

2.3.2.2 Estimates by cause

Estimates of the numbers of blind people in the ROI for each year are presented by primary cause of blindness in Table 2.6. These numbers were derived by applying the cause-based prevalence rates (in Table 2.4) to population projections from the CSO (2008) for the years 2010, 2015 and 2020.

Table 2.6: Projections of blind people in the ROI by cause

	2010	2015	2020
AMD	3,046	3,742	4,628
Cataracts	294	345	403
DR	473	556	654
Other cause	8,110	9,299	10,655
Total blind people (a)	12,995	15,270	17,997

Source: Deloitte Access Economics estimates using NCBI register data (special request, 2010), ROI population estimates (CSO, 2008) and Kelliher et al (2006)
(a) Totals may differ from summed components due to rounding.