Decline in Blindness in Persons Up to Age 65 and the Associated Lost Years of Gainful Employment

Blindness has a substantial effect on the quality of life of those affected and the healthcare system. Blindness during gainful employment is much rarer than at an old age, but those affected are in need of being able to participate in working life to the best possible degree—for example, through vocational development agencies, specialist integration services, and measures for workplace design. According to different estimates, 80 000–500 000 persons in Germany are blind (in the sense of the law) (1). The incidence of blindness has notably declined since the 1990s (2, 3, 4, 5). What is not clear, however, is whether this decline has also occurred in people of working age. This study investigated the time trend in the overall and cause specific incidence of blindness in people aged up to 65, the age at blindness onset, and the years lost to gainful employment.

Methods

We evaluated data from the Municipal Social Association of Saxony for all newly registered recipients of blindness allowance who were younger than 65 at the time of registration. In Germany, everyone is entitled to blindness allowance, independently of their income, if one of the following criteria applies:

• Visual acuity—based on the best corrected visual acuity of the better eye—is 0.02 or less.
• The visual field is limited to a radius of 5° or less.
• Eyesight is equally impaired by a comparable combination of restricted visual acuity and visual field.

The following causes of blindness are coded on the basis of comments from ophthalmologists in their certifications: age related macular degeneration (AMD), cataract, glaucoma, diabetic retinopathy, vascular obliteration, retinal dystrophy, myopia, optic atrophy, cerebral or neurological cause, other cause of blindness, unknown cause (in case the cause of the blindness remained unidentified/was not determined).

We analyzed in Saxony (some 3 million population below 65 years) the incidence of blindness, the age at blindness onset, and the number of lost years of gainful employment overall as well as by specific cause for the time periods 2009–2013 and 2014–2018. The time trend of blindness incidence was studied descriptively by comparing incidence rates in both time periods on the basis of relative risks (RR) with 95% confidence intervals (95% CI) and as a linear trend by using Poisson regression models adjusted for age and sex.

Results

Blindness allowance was granted to 901 persons aged up to 65; the number fell in the later time period (Table: 2009–2013: n=511; 2014–2018: n=390). The most common causes of blindness were retinal dystrophy (n=155) followed by glaucoma (n=111), diabetic retinopathy (n=110), cerebral or neurological causes (n=110) and optic atrophy (n=94).

Table

Cases of blindness (0–64 years) and comparison of the time periods 2009–2013 and 2014–2018 in Saxony

The incidence of blindness fell from 3.32/100,000 population [3.03; 3.60] in 2009–2013 to 2.57 [2.31; 2.82] in 2014–2018. The 23% decline in the total population reached significance (2014–2018 versus 2009–2013: RR=0.77 [0.68; 0.88]). The decline was 4% per year and therefore reached significance for this parameter too (RR=0.96 [0.93; 0.98]). Furthermore, a clear reduction was observed in the causes myopia (RR=0.61 [0.38; 0.98]), cerebral or neurological factors (RR=0.63 [0.43; 0.92]), unknown causes of blindness (RR=0.47 [0.27; 0.62]), vascular obliteration (RR=0.37 [0.12; 1.16]), diabetic retinopathy (RR=0.73 [0.50; 1.07]), and optic atrophy (RR=0.75 [0.50; 1.13]). By contrast, no changes over time were observed for AMD, cataract, glaucoma, retinal dystrophy, and other causes of blindness.

Some 60% of all persons with blindness were male: only 14% were younger than 18. The notable decrease in the incidence of blindness was observed for both sexes and for people up to 18 and older than 18 (data not shown). The average age of blindness onset rose from 42.6 to 43.9 years, and the total number of lost years of gainful employment fell from 10,586 to 7604 (data not shown)—assuming that all persons were in gainful employment before blindness onset but no longer so afterwards. Most lost years of gainful employment were seen in blindness due to cerebral/neurological causes, the fewest were seen for diabetic retinopathy and vascular obliteration. The number of lost years of gainful employment fell especially for the causes AMD, vascular obliteration, retinal dystrophy, myopia, and other and unknown causes. By contrast, this number rose where blindness was caused by optic atrophy or cerebral/neurological causes.

Discussion

Our data show a notable decline in the incidence of blindness and of lost years of gainful employment in people younger than 65 in Saxony. The decline in the incidence of blindness in the total population had already been observed in earlier studies in Baden-Württemberg in the 1990s and 2000s as well as in Saxony from 2009 to 2017 (2, 3, 4, 5). While most of those study populations were older than 80 (60% in Saxony), the present study is the first to show than the incidence of blindness also fell notably in the younger population. Of interest, myopia, cerebral/neurological causes, and unknown causes represent different causes for the decline than in the older population, where the reduction was largely because of less AMD, glaucoma, and diabetic retinopathy. International comparisons are difficult because of available/comparable data. On the one hand, blindness is documented to differing degrees internationally, and on the other hand, different criteria are used to define blindness.

In conclusion, the notable decline in the incidence of blindness in people in gainful employment in Germany is likely to be the result of newly established diagnostic options, such as optic coherence tomography, and better ophthalmologic treatment (surgery for a detached retina, modern intravitreal therapies using VEGF inhibitors, or novel anti-glaucoma drugs).

Heiner Claessen*, Tatjana Kvitkina*, Maria Narres, Bernd Bertram, Andrea Icks

Conflict of interest statement
The authors declare that no conflict of interest exists.

Manuscript received on 1 September 2023, revised version accepted on 20 October 2023.

Translated from the original German by Birte Twisselmann, PhD.

Cite this as:
Claessen H, Kvitkina T, Narres M, Bertram B, Icks A: Decline in blindness in persons up to age 65 and the associated lost years of gainful employment. Dtsch Arztebl Int 2023; 120: 198–9. DOI: 10.3238/arztebl.m2023.0271

References

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