Cataracts surgery has unforeseen benefits

Rates of glaucoma in Scotland are dropping, and the rise in cataract surgery may be to thank

Eye with cataract

Acute primary angle-closure glaucoma (APACG) has long been estimated to rise with the ageing population, but new research suggests cataract surgery boosts may counteract this issue.

A team of hospital ophthalmologists tracked cases of APACG in Scotland between 1998 and 2012, to estimate the rates of the disease in the population. They then compared this to the rates of peripheral iridotomy and cataract surgery, in a paper published in the journal Ophthalmic Epidemiology.

Over the 14 years, the rate of APACG per capita decreased. In 1998, there were 46.7 patients per million Scots, which dropped to 25 per million in 2012.

In the same time, cataract surgeries were boosted by over 70%, following the government’s Action on cataracts initiative in 2000 that provided funding to modernise the operations. The recently released paper concluded that cataract surgery appeared to play an important role in the prevention of APACG.

Peripheral iridotomy rates first dropped between 1998 and 2008, then jumped up over the next four years.

Researcher and consultant ophthalmologist, Dr Stewart Gillan, told OT that his team were expecting to see an APACG drop, based on what was known about the role of the lens in the ocular disease.

He explained: “It is well understood that a crucial aspect of developing angle closure is the adhesions which can arise between the lens and pupil border, leading to ‘pupil block.’ This stops aqueous fluid passing through the pupil into the anterior chamber where it normally drains through the trabecular meshwork, but instead the fluid builds up behind the iris, pushing it forward and closing the angle. This can be exacerbated if the lens is thick, such as in a cataract.”

The paper also noted that, during the time period, the International Society for Geographical and Epidemiological Ophthalmology tightened the classification for primary angle-closure glaucoma (PACG), which may have contributed to the dropping rate.

With only hospital inpatient and day case data used, a push towards outpatient-based care might also have caused a perceived drop, Dr Gillan said.

Experts are predicting PACG will rise in the next 10 years, so a repeat of this research at the end of the decade would be able to confirm or deny such estimates, he emphasised. “It would be interesting for similar studies to be done in other healthcare settings to see if similar results occur,” he concluded.

Image credit: Jonathan Trobe