Glaucoma treatment: a complex puzzle

Michael Chaglasian, Illinois College of Optometry, Chicago, and Eric Schmidt, OD, Omni Eye Specialists, Wilmington, NC, share guidance for ODs about diagnosing glaucoma during the 2022 Vision Expo West in Las Vegas.

Michael Chaglasian, MD, of Illinois College of Ophthalmology, Chicago, and Eric Schmidt, an OMNI ophthalmologist, Wilmington, NC, provided guidance for optometrists to properly diagnose glaucoma.

They emphasized that the key is to know the patient’s risk factors.

In clinical practice, identification of these patients begins with a risk factor assessment that includes a family history of glaucoma and the presence of diabetes mellitus and systemic hypertension.

family contribution

Chaglasian and Schmidt explained that primary open-angle glaucoma is a genetically multifactorial disease. The risk of developing glaucoma in an 80-year-old patient is about 10 times higher than in patients who have close relatives with glaucoma.

While having a family history is important, we hope that new research and advances in genetic testing for glaucoma will lead to a commercially available in-office test that collects DNA via a cheek swab. The laboratory results of the test will give the doctor and patient a risk analysis for the possibility of developing glaucoma in the future. Despite this tendency, other factors unrelated to heredity are closely related to the development of glaucoma.

diabetes component

Having diabetes is associated with about 1.35 times greater risk, than a meta-analysis of several population-based studies. While it is not a strong risk factor for developing open-angle glaucoma, some major studies have indicated that diabetes is a risk factor for developing glaucoma in those who already have the disease.

high systemic pressure

Glaucoma is not associated with high blood pressure (BP), and higher levels may be protective against glaucoma. Hypotension is a factor in ocular perfusion pressure, and the risk of glaucoma increases when ocular perfusion pressure is less than 50 to 55 mmHg.

Likewise, cardiovascular disease is not a typical risk factor for glaucoma.

Clinicians should be aware that rosuvastatin (Crestor, AstraZeneca), a statin, increased the risk of open-angle glaucoma in a few early studies. Statins are not involved in the onset of glaucoma.

When do you get treated?

This is not as simple as treating everyone with intraocular pressure (IOP) over 21 mmHg. Treatment is deferred in patients considered low-risk until there is evidence of glaucoma damage on optical coherence tomography images or on a visual field test.

In patients with significant risk factors, clinicians may decide on treatment early, before any structural or functional changes occur.

This predicament can be resolved by classifying those who should be treated as those with a positive family history and an elevated IOP; those who should not be treated as those with normal images and younger ages; and those with mixed results of suspicious optic nerve, central corneal thickness of 570 μm, and those with unreliable visual fields.

Physicians are advised to follow the Ocular Hypertension Treatment Study Guidelines in Patients with Suspected Glaucoma ranging from 21 to 30 mmHg with normal appearance or suspicious optic nerves but no definitive changes, such as visual field defects and some risk factors, as follows Patients at risk are those with an IOP greater than 22 mm Hg and a central corneal thickness less than 555 μm. Patients with ocular hypertension should generally receive topical medications for a 25% to 30% reduction in IOP.

Treatment decisions vary for different patients with IOPs less than 21 mmHg. Physicians are advised to follow up with patients every 3 to 6 months and to repeat imaging, visual fields, and intraocular pressure measurements. Another option may be to initiate treatment for patients with 3 or more risk factors: a cup-to-disc ratio of 0.8 or more with asymmetric optic nerve heads, African-American heritage, diabetes, suspected field defects and fluctuating IOP values.

Treatment is generally required in those with ocular hypertension and IOP greater than 30 mmHg, the exception being those with a central corneal thickness of more than 600 μm. Of course, any patient has changes in the glaucoma optic nerve. Very distinctive and reliable OCT images, with characteristics of glaucoma; Definite vision loss must be treated.

Chaglasian and Schmidt emphasized that “the diagnosis of glaucoma can be complex, and a step-by-step, structured approach is best.”