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Glaucoma in the clinic

Knowing how and when to intervene in glaucoma requires consideration from the patient’s perspective

Roibeard O’hEineachain

Posted: Saturday, September 1, 2018

An individualised approach to treat glaucoma patients, taking into account all factors that may affect vision and quality of life, can help clinicians steer their course of therapy safely between over- and under-treatment, counsels Ivan Goldberg, Clinical Professor, Discipline of Ophthalmology, University of Sydney, Australia.

“We know that the more basic information that we put together, the more accurate we are likely to be, the greater will be our certainty and the less will be our doubt in our glaucoma diagnostic powers,” Dr Goldberg told the 13th European Glaucoma Society Congress in Florence, Italy.

He noted that patients with chronic diseases like glaucoma will have a different perspective from that of an ophthalmologist. He therefore recommends to his colleagues that they imagine that they are the
patient themselves.

To achieve this, he suggested a review of all the tests the patient is undergoing and the advice and information they have received from staff members. In addition, sitting in the consulting chair and undergoing some of the examinations can further reveal the impact of diagnosis, monitoring and treatment on the patient’s quality of life.

PRESERVING VISION AND QUALITY OF LIFE
He noted that the goal of therapy is to identify risk factors for onset or worsening of disease and then to eliminate or reduce them. In glaucoma, IOP is at present the major proven modifiable risk factor. However, the relationship between IOP reduction and the slowing of vision loss is not linear, and different patients will require different amounts of IOP reduction to achieve optimal results.

Moreover, there are a many lifestyle factors that may contribute to a patient’s disease and the response to IOP-lowering treatment. Patients should be advised to avoid habits like the Valsalva technique, globe compression, physical inversion and water loading, Dr Goldberg said. There are also non-pressure-related aspects that must be taken into consideration, such as genetics and cardiovascular comorbidities. In addition, diagnoses like diabetes should be controlled, and sleep apnoea needs to be detected and treated

GUIDELINES HAVE LIMITATIONS
There are guidelines available for treatment based on randomised controlled studies and anecdotal experience. The general rule is that the more damaging the disease, the more aggressive the therapy advised. The caveats are that their concepts, definitions and strategies are dependent on what the technology can measure.

For example, the invention of ophthalmoscope in the 1860s by von Helmholtz led von Graefe to discover the changes in the optic nerve head that characterise the disease. However, when tonometers became more accurate and available, glaucoma became known as a pressure-dependent disease. This has led to advice and management that may not be appropriate, Dr Goldberg said.

Furthermore, the guidelines cannot promise the desired outcome in each individual patient with absolute certainty, he noted.

“We have to deal with less than certainty because the foundation of science is the opposite of certainty, it is a radical uncertainty about our knowledge and our equipment and an acute awareness of the extent of our ignorance,” Dr Goldberg said.

When a new patient presents with glaucoma, the first question to ask is whether there is structural damage and functional loss, and if there is, whether it is bad enough to threaten the patient’s quality of life. For example, does the damage have proximity to fixation, and what is the extent and the depth of the defects? When monitoring a patient over time it is necessary to determine if they are getting worse, and if so, how quickly, and again, does it threaten the quality of life, and what are the risks of getting worse. The degree of IOP control should be assessed along with the impact any particular treatment will have on the patient’s life.

“Use the cone of uncertainty in the process of examination and get as close to certainty as we can with our patients in our diagnostic considerations, remembering that glaucoma management is a marathon, not a sprint,” Dr Goldberg added.

Ivan Goldberg: ivan.goldberg@sydney.edu.au