Blindness cases climb in 60 to 80 years age bracket

By Roibeard O’hÉineacháin

GOTHENBURG — As the longevity of people in the developed world increases so will their likelihood of becoming visually impaired or blind, according to two Scandinavian studies presented at the 7th International Conference on Low Vision.
Danish and Swedish studies indicated that the incidence of visual impairment increases nine-fold and that of blindness increases five-fold between the ages of 60 and 80 years.

In addition, between 82 and 97 years, the prevalence of severe visual impairment increased a further 10 times and blindness increased a further 40 times.
At the age of 97, 20% were blind but no visual impairment (BCVA greater than 20/40) was also assessed in about 20%, the conference heard.
The Danish study showed that among a randomly selected population of 946 people aged 60 to 80 years, 2.9 % were visually impaired and 1% were blind.

The incidence of visual impairment and blindness increased with the age, rising respectively from 0.9 % and 0.45% among persons aged 60 to 64 years to 8.03% and 3.4%, respectively, among persons aged 75 to 80, Helena Buch MD said.
“We found that visual impairment and blindness were increasingly prevalent among persons aged 60 to 80 years and were associated with increasing age. We also found that our prevalence rates were similar to those obtained in most European studies,” Dr Buch said.

The cross-sectional study involved randomly selected 465 men and 481 women, aged 60 to 80 years, living in the Danish town of Copenhagen.
The participants underwent an extensive ophthalmological examination. Visual impairment was defined as a best-corrected visual acuity in the better eye between 20/40 and 20/200. Blindness was defined as visual acuity of 20/200 or worse.

Overall, cataract was the most frequent cause (50%) of visual impairment, followed by age-related macular degeneration (AMD) present in 34.40%.
AMD was the leading cause of blindness, accounting for 60% of all blind persons. Glaucoma, myopic macular degeneration, cataract and retinitis pigmentosa each accounted for 10% of all bilaterally blind persons.

Dr Buch noted that just as the prevalence of visual impairment and blindness changed with age, so do the causes for visual loss. Among those aged 60 to 69 years, diabetic retinopathy, AMD and cataract were the main causes of visual impairment while retinitis pigmentosa was the leading cause of blindness.

Among those aged 70 to 80 years, cataract was the primary cause of visual impairment, while AMD was the leading cause of blindness and cataract and glaucoma were only infrequent causes.
“We found that the causes of eye diseases were primarily age-related and that cataract and AMD were the main causes. This may be valuable knowledge as we plan for our future aged populations.

“At least 50% of the visually impaired and 25% of the blind persons had conditions such as cataract, diabetic retinopathy and glaucoma which were either surgically treatable or potentially preventable. Thus we can conclude that effective screening and public education can enhance the delivery of eye care,” Dr Buch said.
The Swedish study presented at the conference involved 958 participants aged 70 to 97 years and indicated that in most cases the older an individual is the more rapid his or her visual loss will be.

The participants in the study were the first cohort in an ongoing epidemiological study called H70, started in 1971, and investigating the evolution of visual impairment with age.
The study’s subjects were residents of Gothenburg, Sweden and were born in 1901 and 1902 and underwent repeated ophthalmological examinations at ages 70, 82, 88, 95 and 97 years.

The study showed that the percentage with BCVA of 20/25 or better decreased from 86% at age 70 to 7% at age 95, while no one at age 97 had normal vision.
Furthermore, those with BCVA of 20/200 or less increased from 1.4% at age 70 to 27% at age 97, Birgitta Bergman MD said.

“The population is aging and it is important to focus on the visual function of the elderly to investigate the change of vision in the oldest members of society and to estimate future numbers of visually impaired and visual rehaitation needs,” Dr Bergman said.
The deterioration was faster in the highest age interval, she noted. For example, those requiring optical aids increased from 10% at age 82 to 50% to 60% at ages 95 and 97.
The study also showed a significant correlation between visual acuity and probability of independent living at all ages except at 97 years.

On the other hand, the study also showed that 30% to 40% of those visually impaired with BCVA of 20/80 or less between the ages of 95 to 97 years could continue to live in their own homes with appropriate community and/or family support.
Dr Bergman noted that Sweden would face a challenge in meeting the needs of the visually impaired over the coming decades.
Already the country has the highest proportion in the world of people 80 years or older (4.9%). By 2020, the number of people in Sweden aged 70 years and older will increase by 31%.

However, the burden could be reduced by regular screening of older individuals, she noted. In the present study, 8% of those aged 82 years and 12% at age 88 had vision that could be improved by three lines or more just by changing their glasses.
Furthermore, many would gain greater benefit from cataract surgery if they underwent such procedures while they were still independent members of the community, she added.

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