Glaucoma

Glaucoma is a disease of the optic nerve in which the cells that connect the eye to the brain (retinal ganglion cells) die, causing the optic nerve head to show increased cupping (a central depression where nerve fibers are absent) until it affects the entire nerve, potentially leading to blindness. Increased intraocular pressure, which was once part of the definition, is now considered the main risk factor and the only one we can effectively treat. However, it’s important to note that some patients with glaucoma have normal pressure levels, just as some people without glaucoma may have high pressure.

Types

There are more than 30 different types of glaucoma. A simpler classification would first include congenital glaucomas (which often occur due to malformation of the eye) and are, in the vast majority of cases, treated surgically. The second type would be open-angle glaucoma, the most prevalent in Brazil (with few symptoms in its early and moderate stages). A third type would be angle-closure glaucomas, which occur in acute and severe episodes, potentially causing blindness if not treated promptly. Lastly, there are secondary glaucomas, which occur due to various causes such as trauma, bleeding, tumors, etc.

Symptoms

It takes a considerable amount of time for patients to notice vision loss from glaucoma. This is because the visual system has a protective redundancy—multiple cells transmit the same stimulus. If one eye is severely affected and the other is normal, the brain compensates, masking the loss. In short, vision loss is late but irreversible.

When significant loss occurs, patients may experience symptoms related to reduced retinal sensitivity, such as:

• decreased contrast perception
• difficulty and slowness in reading
• trouble adapting to light and dark

These issues can lead to depression, increased risk of falls, and reduced quality of life. Pain may occur in cases of sudden intraocular pressure spikes. Open-angle glaucoma typically does not cause pain, unlike acute angle-closure glaucoma or neovascular glaucoma, which can affect diabetic patients or those with retinal vein thrombosis.

A notable symptom not caused by glaucoma itself but by its treatment includes red eyes, dark circles, eyelash growth, loss of orbital fat, and dry eyes—side effects of common eye drops.

Diagnosis

Diagnosis is made through a comprehensive eye exam: intraocular pressure is measured, the angle between the iris and cornea is assessed using a contact lens (to determine if it’s open or closed), and the optic nerve and retina are examined via fundoscopy. If glaucoma is suspected, functional testing (visual field) and structural imaging (retinal and nerve photos, nerve fiber layer thickness via optical coherence tomography) are performed. Patients are  followed up over time.

A patient is only diagnosed with glaucoma if there is worsening of these parameters. Disease control is confirmed when no progression is observed.

Treatment

Initial treatment involves eye drops or laser therapy. Laser is a great option, though still underused in Brazil, with a 50–60% success rate and high safety.

If laser and drops are insufficient or not tolerated, surgery is an option. Surgical approaches vary by case, from minimally invasive procedures to drainage implants or aggressive laser treatments that destroy the fluid-producing tissue (cyclodestructive procedures).

In some types of glaucoma, such as angle-closure glaucoma, the lens contributes to the problem. In these cases, cataract surgery to remove the lens can open the angle completely and potentially eliminate the need for further treatment. However, if the angle is chronically closed and already damaged, lens removal alone is not enough. Cataract surgery is not a treatment for open-angle glaucoma—a common misconception.

Is there a cure for glaucoma?

There is no cure, but it can be controlled. Dead cells do not regenerate. Early detection is crucial for starting treatment. Unfortunately, diagnosis often occurs in advanced stages. Even then, progression can be halted or slowed.

It’s important to note that patients with high intraocular pressure but no glaucoma should only be treated if the disease is confirmed. Treating non-glaucomatous patients carries risks, as treatment is lifelong and not without side effects. These patients should be monitored regularly and only treated if structural or functional changes occur.

Risk Factors

There are risk factors for glaucoma, including for specific types. Family history is very important. Anyone with relatives who have glaucoma—especially first-degree relatives—should inform their ophthalmologist, who will perform a more detailed evaluation and recommend regular check-ups.

Myopia is a risk factor for open-angle glaucoma, while hyperopia is a risk factor for angle-closure glaucoma. Most people who have undergone myopia surgery will have falsely low pressure readings. In other words, their actual eye pressure is higher than what the device measures. This happens because myopia surgery alters the physical properties of the cornea, and the device is calibrated for normal corneas.

Age is also a risk factor. The incidence increases almost exponentially with age. After age 50, the prevalence is around 2%, and after age 75, it can exceed 15%. Black individuals have twice the prevalence, respond less effectively to treatment, and are more likely to go blind from the disease. East Asians have a higher incidence of normal-tension glaucoma and chronic angle-closure glaucomas.

Low blood pressure is another important risk factor. A particularly concerning combination is high eye pressure and low blood pressure. Glaucoma patients who are being treated for hypertension should talk to their cardiologists to avoid treatments that cause excessive hypotension.

Diabetes is a controversial risk factor. However, uncontrolled diabetes that leads to proliferative diabetic retinopathy can cause a severe form of neovascular glaucoma.

Corticosteroids

The use of corticosteroids can worsen glaucoma. Five percent of the general population responds with ocular hypertension, which can be quite severe, when using corticosteroids—even facial creams, pills, injections, shampoos, and especially eye drops. This is particularly true with prolonged use. Unfortunately, corticosteroids in any form are often sold over the counter, and there are still many cases of children who have gone blind due to the improper and uncontrolled use of corticosteroids for treating eye allergies. Corticosteroids should only be used with a prescription and under medical supervision.

Other drugs are risky for people with narrow angles, due to the risk of angle closure. These include drugs that can dilate the pupil, such as antidepressants, certain sedatives, and medications for urinary incontinence. Since neither the patient nor the prescribing physician usually knows the anatomy of the individual’s eye angle, the recommendation is to check for a family history of glaucoma or hyperopia. In such cases, an ophthalmologist should always be consulted to assess the risk and, if necessary, perform a laser procedure (iridotomy) to prevent angle closure.

By Einstein Editorial Board