Patients

by Dr. Cesar A. Perez, Jr.

The eye is a hollow ball-like organ, roughly the size of a lanzones fruit. In front are the transparent cornea and the white sclera; inside are the iris, lens and the retina. At the back is the optic nerve. Vision passes from the cornea, through the clear aqueous fluid, through the center of the iris called the pupil, through the crystalline lens, through the clear vitreous gel, and stops at the retina. Impulses are then transmitted from the retina to the brain via the optic nerve.

(From NEI Website)

by Dr. Cesar A. Perez, Jr.

Glaucoma is a group of eye diseases that mainly damages the optic nerve, which leads to visual loss and blindness. Unlike other eye problems, glaucoma usually has no signs and symptoms especially in its early stages. In its late stage, peripheral vision is affected which eventually leads to permanent visual handicap.

by Dr. Cesar A. Perez, Jr.

Individuals who have the following risk factors are prone to develop glaucoma:

• advancing age
• previous trauma or surgery to the eye
• diabetes
• near-sightedness (myopia)
• previous intake of steroid medications
• relatives diagnosed previously with glaucoma

by Dr. Cesar A. Perez, Jr.

It is the main nerve connecting the eye to the brain, roughly the same width as a regular pencil. It transmits signals coming from the retina towards the brain. It is made up of over a million microscopic nerve cells.

Ophthalmologists can examine the front part of the optic nerve, called the optic disc. Glaucoma patients usually manifest certain patterns of changes in the optic disc, thus the importance of regular eye examination. Changes in the structure and appearance of the optic disc usually coincide with functional and visual changes as well.

by Dr. Cesar A. Perez, Jr.

It is the pressure inside the eye brought about by the amount of fluid within its cavity. It keeps the integrity of the structure of the eyeball. Too much fluid inside makes the intraocular pressure high. High eye pressure is one risk factor in developing glaucoma.

The pressure is measured in units of mmHg, the usual normal range of pressure is from 10-21 mmHg.

The picture below shows the path of fluid production responsible for the basis of the intraocular pressure. Any imbalance in this flow results in fluid retention and subsequent elevation of intraocular pressure. In the same way, decreasing the production of fluid and increasing its drainage result in reduction of pressure.

(From the NEI website)

by Dr. John Mark De Leon

A visual field (or perimetry) is an indispensable test for diagnosing and monitoring glaucoma. The test maps out one’s scope (or field) of vision and usually takes about 5-15 minutes per eye. It tests each eye’s central vision (what one sees looking straight ahead looking at a target) and peripheral (side) vision (the rest of what one sees at the sides when looking at a target) which is usually affected first by glaucoma. Each eye is tested separately since the visual fields of both eyes overlap centrally so blind spots in one eye may not be noticed by the patient since the other eye’s vision could compensate for this. This test can detect these peripheral blind spots which develop discretely and cannot be noticed by the patient especially in the early stages of glaucoma. This test is very subjective so results will depend on the patient’s alertness, cooperation, and proper instructions from the technician assisting the patient. Results of the test support the diagnosis of glaucoma if it correlates with other parts of the eye examination (e.g. eye pressure check, optic disc evaluation, etc.) that also point to glaucoma. The diagnosis of glaucoma cannot be entirely made on visual fields alone. This test is also very important because it can monitor if glaucoma, once diagnosed, is stable or getting worse so tests will have to be done periodically so they can be compared with one another.

by Dr Maria Hannah Pia de Guzman

Glaucoma can be detected when the patient is examined in the ophthalmologist’s clinic. The part of the optic nerve that is inside the eyeball, called the optic disc or optic nerve head, can be seen when the doctor looks inside the eyeball using special lenses and lights in an examination technique called funduscopy. The doctor can determine if the optic nerve head looks normal, suspicious, or definitely abnormal. Due to the wide variation in the appearance of normal optic discs this determination can sometimes be tricky.

The part of the eye where the intraocular fluid naturally drains (the trabecular meshwork, located in the anterior chamber angle) can be viewed with special lenses in an examination called gonioscopy. The doctor can see if the meshwork is blocked (“closed”) or not (“open”).

Another aspect of the eye examination is measuring the pressure inside the eyeball (intraocular pressure) because this may be elevated in cases of glaucoma. This examination is called tonometry and there are many different instruments that can be used.

After the examination the doctor considers the patient’s history and the findings and decides whether to request for some diagnostic tests and/or recommend glaucoma treatment.

by Dr. Ernesto Pangalangan, Jr.

Primary open angle glaucoma (POAG) is the most common type of glaucoma in some parts of the world. In POAG, the intra-ocular pressure (IOP) is higher than the statistically normal IOP which is about 10-21 mmHg. If the IOP is not lowered, this can result in optic nerve damage which can lead to irreversible blindness.

POAG is a chronic, progressive optic neuropathy characterized by optic nerve head (ONH) and retinal nerve fiber layer (RNFL) changes, usually with corresponding visual field defects. The IOP is usually above 21mmHg and the irido-corneal angles are open on gonioscopy. It usually appears spontaneously and may be an incidental finding in a routine eye exam without any antecedent or related disease and has no known basis other than genetic or familial predisposition. It is usually asymptomatic until late in the disease where decreased peripheral and central vision may be noted. While typically bilateral, it can be asymmetric.

Risk factors for POAG are the following: elevated IOP (greater than 21 mmHg), positive family history, older age, race, myopia (higher than 4 diopters) and those with vascular factors like cardiovascular disease, systemic hyper/hypotension, vasospastic phenomena and diabetes mellitus. An optic disc finding of a disc hemorrhage could mean progression of the disease.

Early detection is of utmost importance. Diagnostic evaluation includes a careful history, slit-lamp examination, IOP measurement, gonioscopy (examination of the fluid drain of the eye) and perimetry (testing of the field of vision). Newer modalities like the quantitative optic disc and retinal nerve fiber layer imaging (OCT, HRT) or selective perimetry (FDT, SWAP) may also be done.

Mainstay of therapy of this disease is lowering of IOP. Depending on the stage, medication (eyedrops), laser, or incisional surgery can be used to control the IOP. Since there is no cure for glaucoma, lifelong monitoring is needed.

by Dr Maria Hannah Pia de Guzman

One common type of glaucoma is primary angle-closure glaucoma. The term “primary” is used for diseases where there is no identifiable cause. The term “angle-closure” means that the anterior chamber angle (angle) is blocked by the iris (the colored part inside the eye). The angle is where the trabecular meshwork (TM) is located. The TM is the structure that constantly drains the fluid inside the eye. Think of it like the drain in a sink. Constant drainage is needed to balance the constant production of fluid by the ciliary body (like a faucet that is always open). If the faucet remains open but the drain is blocked the sink overflows. However, because the eyeball is a closed system, the fluid accumulation leads to elevation of the eye pressure in the same way that a ball that is pumped with too much air becomes hard. Elevated eye pressure can damage the optic nerve head thus leading to glaucoma.

Angle-closure can detected by the ophthalmologist in the clinic using a special lens in an examination called gonioscopy. There are also some special machines that can be used to view, measure, and document the angle.

A narrow angle or a recently closed angle can be opened using certain laser techniques. However, angles that have been closed for too long become stuck in the closed position and may no longer respond to laser and might need to be treated with surgery.

by Dr. Gertrude Gwendale Baron-Reinoso

Secondary glaucomas are glaucomas with identifiable causes. The cause could be a primary ocular condition or disease, a systemic disease, a drug or eye trauma.

Inflammatory Glaucoma

This type of glaucoma is caused by eye inflammation or uveitis. In uveitic open angle glaucoma, there is inflammation of the trabecular meshwork (trabeculitis) or blockage of the trabecular meshwork by inflammatory cells and byproducts. In uveitic closed angle glaucoma, adhesion of the iris to the angle structures (synechia) prevents drainage of the aqueous. Treatment involves the use of anti-inflammatory drugs and appropriate measures to lower eye pressure.

Neovascular Glaucoma

In patients with diabetes mellitus, vascular abnormalities result in poor blood supply to the retina. Ischemia triggers the growth of abnormal blood vessels (neovascularization) in the retina as well as in the anterior chamber angle. These abnormal vessels effectively block the drainage channels in the eye. Panretinal photocoagulation for diabetic retinopathy as well as glaucoma surgery are essential for treatment. Aside from diabetes, central retinal blood vessel occlusion can also cause neovascular glaucoma.

Traumatic Glaucoma

Any injury to the eye can lead to traumatic glaucoma. In the acute phase, red blood cells in the anterior chamber (hyphema) can clog up the angle and raise the intraocular pressure. In other cases, blunt trauma can rip the trabecular meshwork as seen in angle-recession glaucoma. This type of glaucoma can occur from weeks to even months after the injury due to scarring of the meshwork. Lens-Induced Glaucoma

A complication of untreated cataract is lens-induced glaucoma. A large cataract (intumescent lens) can cause pupillary block and angle closure (phacomorphic glaucoma). A leaky cataract can cause inflammation in the anterior chamber and increased eye pressure (phacolytic glaucoma). In addition to adequate pressure control, cataract surgery has to be performed.

Steroid-Induced Glaucoma

Long-term use of steroids whether as eye drops, eye ointments, injections or oral medications can trigger a rise in intraocular pressure. It is believed that a cascade of reactions leads to increased resistance to aqueous outflow in the trabecular meshwork. Some individuals are more susceptible to pressure spikes brought about by steroids than others.

Pigmentary Glaucoma

Pigmentary glaucoma is a type of secondary glaucoma more commonly found in young adult males. Pigment granules from the iris are dispersed into the anterior chamber eventually blocking the trabecular meshwork. Treatment is like that of primary open angle glaucoma.

by Dr. Irene R. Felarca and Dr. Edgar U. Leuenberger

Congenital glaucoma occurs less frequently than adult glaucoma. It is seen in 1 in 10,000 births. This condition results from developmental defects of the eye’s internal drainage system leading to increase in eye pressures. This disease entity is seen at birth or early childhood. High eye pressures can also be seen in older children and young adults but they do not have enlarged eyes. Their condition is called juvenile glaucoma. Since young children or infant’s eyes have elastic eyeballs, increased intraocular pressure leads to enlargement of the eyes. Elevated eye pressure leads to swelling and haziness of the cornea or the front part of the eye, causing blurred vision, tearing, light sensitivity and eyelid spasm. If high eye pressure persists, the eye would further enlarge accompanied by optic nerve damage and ultimately permanent blindness.

The mainstay for treatment of congenital glaucoma is surgery. This is done by making an incision on the abnormal tissue of the eye’s internal drainage system (goniotomy). For complicated cases, an alternate drainage or canal is created (trabeculectomy). There are some instances where pressure is still uncontrolled and a small tube is placed inside the eye to drain the internal fluid (glaucoma drainage device surgery). In resistant cases, laser surgery (cycloablation) is done to shrink the structure that produces the internal fluid of the eye. Nevertheless, the patient and the family should be aware that high pressures might return at any age hence follow-up is warranted throughout their life. Early recognition is essential to preserve vision, maximize visual potential, and help the child become a useful member of society.

by Dr. Nilo Vincent Florcruz II

Although it is recognized that not all glaucoma patients demonstrate elevated intraocular pressure and not all glaucomatous optic nerve damage is attributable to pressure damage per se, current standard glaucoma care is devoted almost exclusively to reduction of intraocular pressure. Bringing pressure down into the normal or low normal range (17 mm Hg or less) can be expected to arrest progression or dramatically slow its course in the vast majority of cases. At the same time, it must be recognized that some unfortunate individuals, diagnosed late with end-stage nerve damage, with an unusually sensitive optic nerve, or who are primarily sensitive to non-pressure factors, will continue to show unabated visual field loss despite maximal pressure lowering. These are the individuals to whom future research regarding other non-pressure causative factors and their treatment must be directed. Three methods for glaucoma pressure-lowering treatment are available: medical (usually eyedrops), laser, and surgical. Since the threshold of pressure damage varies among patients, the only reliable indicators of glaucoma stabilization are stability of the visual field and prevention of optic nerve damage. In the usual glaucoma therapy, intraocular pressure may be lowered by any or all of the three methods (drops, laser and surgery). In a normal, non-glaucomatous population, intraocular pressure averages approximately 16 mmHg and most (95%) will fall between 10 mmHg and 24 mmHg. In the glaucomatous population, the mean intraocular pressure is somewhat higher and the range much broader, even as high as 70 mmHg where arterial circulation to the eye begins to be compromised. Typically, however, the early untreated open angle glaucoma patient will manifest an eye pressure in the mid-20s. Measurement of intraocular pressure at different times of the day establishes the degree of pressure variability before glaucoma therapy is started. The experienced ophthalmologist typically will determine a “target pressure” as a goal to achieve with pressure-lowering therapy, recognizing that the goal may have to be revised based on future assessment of the visual field.

by Dr Maria Hannah Pia de Guzman

Various laser techniques can be used to treat, prevent, or mitigate glaucoma. No single technique works for all glaucoma patients. The applicable technique depends on the type of and stage of the glaucoma. Iridotomy is used to widen a narrow angle or open a closed angle by reducing the pressure that is pushing the iris forward towards the trabecular meshwork. Iridoplasty is used to widen a narrow angle or open a closed angle by forcing the iris away from the meshwork. Trabeculoplasty is a treatment applied to the trabecular meshwork to stimulate it into draining fluid more efficiently. It can only be done through an open angle. Cyclophotocoagulation is usually used for advanced or end-stage glaucoma. It causes partial destruction of the ciliary body (the eye structure that produces intraocular fluid) to reduce fluid production. Laser suture lysis is used to adjust fluid flow after the glaucoma operation called trabculectomy.

As with all types of glaucoma treatment, laser treatment does not cure the disease but only controls it or prevents progression. Laser treatment may need to be combined with other types of treatment. The patient still needs lifelong monitoring even after successful laser treatment.

by Dr Maria Hannah Pia de Guzman

Various types of surgery can be used to lower intraocular pressure. Since surgery is riskier than medical or laser treatment it is often only done when other types of treatment are inadequate, not applicable, or not expected to work. The exception to this is infantile glaucoma (a.k.a. congenital glaucoma) for which surgery is the primary treatment although medications can be used temporarily while preparing for surgery.

Trabeculectomy is the most commonly performed glaucoma surgery. It can be used for both open-angle and angle-closure glaucoma. It involves the creation of an alternative fluid drainage pathway out of the eye’s own tissue. The new pathway goes from the anterior chamber to a pocket under the transparent lining (conjunctiva) of the white part of the eye (sclera). The most common complications of this procedure are too little or too much fluid drainage and cataract formation or progression. The effectiveness of the procedure usually lasts for several years but eventually starts to decrease due to the body’s natural attempt to heal (close) the unnatural pathway.

There are many different kinds of implants that can be used with or instead of a trabeculectomy. These implants are called glaucoma drainage devices. They are usually used in cases where a trabeculectomy is not expected to succeed. There are also implants that can be inserted using minimally invasive techniques although they tend to be less effective than trabeculectomy (higher intraocular pressures achieved).

Even with successful surgery glaucoma still cannot be cured and patients need to be monitored continuously for intraocular pressure control and progression of the glaucoma.