An international perspective on glaucoma

Global perspectives on glaucoma were discussed during a session led by CHEC ophthalmic surgeon, Moemen Elnawawy, on the Sunday of 100% Optical (2 March).

Opening the lecture, Elnawawy noted that glaucoma is the second most frequent cause of blindness globally, after cataracts.

It is the most frequent cause of irreversible damage, and often appears earliest in black ethnicities, he said – whilst emphasising that anyone can be diagnosed with the condition.

He noted that age and intraocular pressure (IOP) are important risk factors.

High myopes and those with thinner corneas are also at risk, Elnawawy said, as are those who do not regularly attend eye examinations and those with a family history of the condition.

Elnawawy also ran through the suggested frequency of eye examinations for those with and without high risk factors for glaucoma, advising that those at the highest risk are examined every six months.

A 3% increase in the prevalence of glaucoma in the US can be expected by 2030, he revealed.

There is an expected increase in prevalence of 2% in the UK in the same period, matched by a 2% increase in France.

“It is going up over the world,” Elnawawy said, adding: “as healthcare systems are improving, people live longer, so they are more likely to get it.”

He added: “Glaucoma is primary, secondary or congenital. You can be born with it. You can get it throughout your life, or it can be somewhat genetic.”

Secondary glaucoma can come about after trauma, diabetic retinopathy, chronic steroid use, vein occlusion, or uveitis, Elnawawy said.

Diagnosing and treating glaucoma

Primary open angle glaucoma can be asymptomatic in the early stages, whilst later patients may experience tubular vision, Elnawawy said.

“The first sign of glaucoma damage is damage to the thickest part of the optic nerve,” he said.

He also emphasised that, whilst glaucoma can be bilateral, it may not always be symmetrical.

Disc haemorrhages, Elnawawy noted, can denote optic damage.

He shared photographs of normal and abnormal optic discs with attendees, whilst explaining how glaucoma progression can be seen through the patients’ blind spots.

Elnawawy went on to share the recommended assessment and follow-up for each stage of ocular hypertension and suspected primary open angle glaucoma, whilst emphasising that the latter cannot be treated – it should be controlled instead.

Considering the medical perspective, Elnawawy noted that beta blockers may sometimes be prescribed, but that practitioners should be aware of potential side effects, including depression, in this instance.

He also noted that topical adrenergic agonists may cause ocular side effects, such as a burning sensation, while topical cholinergic agents have the potential to increase myopia and cause nausea and vomiting.

When it comes to treatment not being effective, Elnawawy reminded practitioners that the failure of medical therapy is not necessarily the patient’s fault.

Late detection, lack of understanding over the disease, poor compliance due to a complex regimen, discomfort with drops, or allergies, might all be reasons for treatment to fail, Elnawawy said.

He also noted the importance of prescribing preservative-free eye drops, as there is evidence that preservatives increase levels of glaucoma over time.

Drainage implants, laser trabecular treatments and trabeculectomy can all be effective treatments for glaucoma if drops fail at stopping disease progression, Elnawawy said.

How activity affects IOP

Elnawawy explained how eye pressure can be transiently affected by exercise where the subject is holding their breath, and when a subject is using wind instruments.

He used the example of a professional trumpeter, who had an IOP of 40 whilst working but of eight when at rest.

He went on to note that there have been eight studies and trials in this area, going back to 1994.

In 1998, a trial found that early treatment reduced instances of primary angle glaucoma, with the greatest effect in those with higher levels of the condition, Elnawawy said.

He also referenced the UK GTS Glaucoma Treatment Study, from 2012, which tested the hypothesis that treatment with topical prostaglandin analogues reduced the frequency of visual field deterioration in open angle glaucoma patients by 50% over two years when compared with placebo.

Angle closure accounts for 10% of glaucoma cases in the US, Elnawawy said, noting that the highest risk groups include the elderly and those with hyperopia.

Patients will often present with symptoms including redness, nausea and vomiting, ocular pain and headaches, he said, and 58%–75% will go on to have an attack in the other eye.

Elnawawy advised medical treatment in these cases, until a patient’s pressure reduces, followed by a laser peripheral iridotomy.

For glaucoma care, “patients need to go to the best people in their field, which are the best people in this room,” he concluded.