What is glaucoma?

Glaucoma is a buildup of pressure in the eye that can damage the optic nerve. Left untreated, it can eventually cause blindness. About 1.5 million Americans living with glaucoma are undiagnosed. While it’s most frequently diagnosed in older adults, it can occur at any age.

What causes glaucoma?

Tiny channels that run between the cornea and the iris drain excess eye fluid. These channels can become obstructed, and as fluid builds up in the eye, intraocular pressure (or IOP) increases, leading to glaucoma. “It's like tire pressure,” Dr. Rohring explains. “The pressure has to be just right. Too much or too little can cause problems.”

Given time, this pressure can damage the optic nerve. Common risk factors for glaucoma include:

• Underlying conditions like diabetes or hypertension
• Age
• Trauma to the eye
• Near- or farsightedness
• Genetic predisposition — family history can make it more aggressive, meaning it starts earlier and progresses more quickly

“This is what prompts most patients to come in and that's when we find they're already in the late stages of the glaucoma.”

There is one type, acute angle-closure glaucoma, that can cause symptoms before vision loss. Those include excruciating eye pain, nausea and sensitivity to light. Generally, though, a patient won’t have the luxury of such warning signs, Dr. Rohring explains, which is why regular testing is paramount for people of all ages.

"Early detection is crucial for managing glaucoma effectively,” she says. “Diagnosing the condition involves a thorough examination of the eye, particularly the optic nerve, which is where the damage occurs.”

Glaucoma tests

There are several tests ophthalmologists use to help them determine the presence and/or severity of glaucoma.

Tonometry measures the intraocular pressure inside the eye. The most common method is applanation tonometry, which gently applies pressure to the cornea. “We apply a little bit of pressure to the outside of the eye, and then we see how much rebound pressure we get back,” Dr. Rohring says.

Another technique called pneumatic tonometry, also known as the “air puff” exam, uses a quick pulse of air to slightly depress the cornea, recording the degree of deformation. “This isn’t used as often because it has shown to be less accurate,” she says.

Gonioscopy involves the use of a goniolens (a special type of contact lens), which is held against the eye to observe the angle between the iris and cornea. Consequently, this test is helpful in diagnosing narrow- or closed-angle glaucoma. “This helps us evaluate if fluid is draining properly, or if it's partially or completely obstructed,” Dr. Rohring says.

Fundus photography provides imaging of the fundus — a structure at the back of the eye that houses the optic nerve. A compromised or weakened optic nerve could be a sign of glaucoma.

Optical coherence tomography (OCT-RNFL) uses light waves to take a more detailed cross-sectional image of the optic nerve, helping to measure its thickness. OCT-RNFL is used to monitor the loss of nerve fibers in glaucoma patients over time and assess the progression of the disease.

Visual field test assesses peripheral vision loss, a key indicator of glaucoma. The patient is asked to detect lights shown in their peripheral vision, and any blind spots are noted.

Pachymetry measures the thickness of the cornea, as thinner corneas can increase the risk of glaucoma.

Glaucoma eye drops: The first line of defense

Glaucoma treatment, in most cases, begins with eye drops. The mechanism of the eyedrops’ action varies. Some eye drops work by increasing fluid drainage in the eye. Those include:

• Prostaglandin analogs (taken once daily)
• Rho kinase inhibitors (used when other treatments are not sufficient to lower IOP)

Others reduce the amount of fluid that the eye produces, in turn lowering the burden on the drainage channels. Those include:

• Beta-blockers (typically used twice a day)
• Carbonic anhydrase inhibitors (usually used when other medications have not been effective)

Still others like alpha agonists combine both mechanisms, making them convenient for patients who need multiple medications.

“Eye drops are only effective if patients adhere to a strict schedule,” Dr. Rohring says. “Some experience side effects like eye irritation or redness, but these can usually be managed by adjusting the treatment regimen.”

Glaucoma laser surgery

Laser procedures are increasingly used to manage glaucoma, especially when eye drops aren’t effective or cause side effects. These minimally invasive options have fewer side effects and shorter recovery times than traditional surgery. The two most common types of glaucoma laser procedures are:

Selective laser trabeculoplasty (SLT): A short laser procedure used to treat open-angle glaucoma by lowering eye pressure. SLT targets specific cells in the drainage angle of the eye, stimulating a biological change that improves fluid drainage. While effective — about 75-80% of patients see a significant reduction in IOP — this is not a permanent solution and the procedure may need to be repeated. Results typically last for 1-5 years.

Laser peripheral iridotomy (LPI): Indicated for narrow-angle glaucoma, a condition where the iris physically obstructs the drainage passageway. This laser surgery creates a small opening in the iris, allowing fluid to bypass the obstruction and flow freely, relieving pressure. With a high success rate, LPI typically provides long-term relief.

Glaucoma surgery

When glaucoma doesn’t respond to the previous options, more invasive surgical options are available. Two procedures make up the bulk of traditional glaucoma surgeries:

• Trabeculectomy: This approach involves creating an opening in the white of the eye beneath the eyelid. This allows fluid to drain and lowers ocular pressure.
• Tube shunt surgery: This used to be reserved for patients who didn’t respond to trabeculectomy; now it’s considered a viable first option. A surgeon implants a plastic shunt in the eye to allow excess fluid to drain.

“Trabeculectomy is generally considered more effective, while tube shunt surgery is less likely to produce complications,” Dr. Rohring says.

Whether eyedrops, laser or traditional surgery, all glaucoma treatments are considered “secondary prevention” measures — meaning they don’t reverse damage to the optic nerve that has already occurred. Rather, they aim to prevent further progression of glaucoma and preserve as much nerve function as possible.

What are cataracts?

This eye condition is a clouding of the usually clear lens, and it blurs your sight. “It’s like looking through a dirty glass window,” Dr. Rohring says. “For the light to get inside the eye it must pass through the lens and if the lens is cloudy then you're not going to be able to see well.”

As is the case with glaucoma, untreated cataracts can cause partial or even total vision loss; they’re responsible for more than half of all cases of blindness worldwide.

• Nuclear sclerosis cataracts: The most common of the three, these start at the center — or nucleus — of the lens and spreads outward.
• Cortical cataracts: These begin along the edge of the lens and slowly spread towards the center.
• Posterior subcapsular cataracts: Beginning behind the surface of the eye at the back of the lens, this type of cataract grows toward the front of the eye. These can progress quickly and are difficult to remove due to their proximity to the lens capsule — a thin, delicate membrane protecting the lens from outside agents. If you use steroids to treat conditions like asthma, you may get this type of cataract.

Catching cataracts early

Fortunately, it’s possible to spot cataracts early. Unlike glaucoma, cataracts produce symptoms, plus they’re actually visible — the protein clumps produce a milky hue in the lens.

People with the disease experience varying degrees of blindness depending on how far the cataracts have progressed.

Stage 1: Early cataracts

In the early stages of cataracts, the clouding of the lens is minimal. Vision begins to blur slightly, particularly in areas of fine detail, but it may be hard to notice at first. People may have trouble reading small text or recognizing faces at a distance.

Stage 2: Immature cataracts

As the cataract develops, the vision becomes more blurred and less sharp, especially in lower lighting conditions. This stage is often characterized by a gradual increase in glare or halos around lights, making it difficult to drive at night. Colors may begin to appear less vibrant, and the lens starts to take on a dull or faded appearance.

Stage 3: Mature cataracts

By the time the cataract reaches the mature stage, the lens has become significantly clouded, making it hard to see clearly in low-light or nighttime conditions. Daytime vision may also be noticeably reduced, as the cloudiness in the lens blocks more light, causing the vision to appear hazy and foggy.

Stage 4: Hypermature cataracts

In the final stage, the cataract becomes completely opaque, and the lens appears yellowed or even milky. At this point, the vision loss is significant, and the patient is likely to be nearly or completely blind. The lens may also harden, making it difficult for the surgeon to remove it during surgery. Additionally, the pressure inside the eye may increase, potentially leading to secondary glaucoma, a condition where the increased pressure further damages the optic nerve and worsens vision. In this stage, cataract surgery becomes necessary to restore vision.

How to prevent cataracts

As is the case with glaucoma, cataracts can be slowed or prevented by following healthy habits. Such measures include:

• Improving diet
• Avoiding smoking and alcohol
• Using protective eyewear in bright sunlight

Cataract treatments

If your vision becomes so impaired that you’re struggling to read, drive or watch television, your doctor may recommend cataract surgery. Currently, there aren’t any non-surgical treatments for cataracts.

Cataract surgery is typically an outpatient surgery and eye surgeons can do the procedure with local anesthesia. A patient's clouded lens is removed, and an artificial lens is inserted in its place. Unlike glaucoma treatments, surgery for cataracts can restore vision. “It depends on how cloudy their lens is, but patients can go from just seeing shadows to regaining 20-20 vision after cataract surgery,” Dr. Rohring says. “The last couple of decades have brought tremendous improvement in our surgical technique, patient outcomes and safety.”

Recent developments in cataract surgery include:

• Advanced intraocular lenses (IOLs): These lenses provide patients with a broader range of vision, reducing or eliminating the need for glasses after surgery. One example is light adjustable lenses (RxSight), which are implanted in the eye and allow for fine-tuning of vision even after the surgery. Now offered at several Northwell locations, the lens can be adjusted using ultraviolet light to optimize vision. “These in-office treatments can actually change the prescription of the eye,” says Dr. Rohring, “so, if you're not happy with the results of surgery, we can make adjustments until you achieve the vision you want.”
• Phacoemulsification: This minimally invasive technique involves using ultrasound waves to break up the cloudy lens into smaller pieces, which are then suctioned out of the eye. It leads to faster recovery times and smaller incisions compared to older methods, such as extracapsular cataract extraction.
• Smaller incisions: Modern cataract surgery uses micro-incision techniques that allow for smaller cuts in the eye (typically around 2-3 mm). This reduces the risk of infection, minimizes scarring, and often eliminates the need for stitches, resulting in quicker recovery and less discomfort.
• Preoperative imaging and planning: Special types of imaging tests that take detailed pictures of the inside of the eye allow surgeons to better plan for lens implants and optimize the surgical approach. One that captures the optic nerve and retina is called ocular coherence tomography (OCT). Another test known as topography-guided imaging maps the shape of the cornea, the clear front part of the eye. It helps the surgeon understand any irregularities in the cornea, which is important for selecting the right lens implant and improving the chances of clear vision after cataract surgery.
• Biometry: Modern biometry (measurements of the eye) helps to more accurately calculate the proper lens power needed for optimal vision after surgery. This reduces the chances of post-surgery refractive errors.
• Enhanced visualization for surgeons: The use of high-definition microscopes and video-assisted systems enables surgeons to have a more detailed view of the eye during surgery. This increased visibility leads to higher precision in delicate maneuvers, improving the safety and outcomes of the procedure.

To find out more about chronic eye diseases, click here.