Glaucoma is a disease of the optic nerve of the eye, which is basically the structure that relays what the eye sees to the brain. The major risk factor is represented by the intraocular pressure (IOP) that, when sufficiently elevated, will damage the optic nerve. If left untreated, continued damage to this structure may lead to visual field defects, visual impairment (noticed as foggy/cloudy vision), and blindness.
The eye contains a fluid known as aqueous humor that provides nourishment to its internal structures. This fluid is produced behind the iris (colored portion of the eye) and then is drained out through a sieve-like structure called the trabecular meshwork at the front part of the eye. In some eyes, abnormalities in the drainage system lead to impairment of the normal aqueous humor outflow, and IOP increases. This high IOP may damage the optic nerve head located in the back part of the eye and impair the communication between the eye and the part of the brain responsible for the vision. In other cases, IOP may be relatively normal, but glaucoma occurs anyway because of the inability of the eye to handle mechanical stress where the nerve fibers leave the eye, or because of poor blood supply to these same nerve fibers.
In glaucoma, the optic nerve gets damaged. A portion of the optic nerve may be assessed during the eye exam, where it can be seen as a round structure (optic disc), with the pink or reddish section representing the neural tissue that takes the visual information to the brain. The whitish central part represents absence of neural tissue, and it is called the “cup”. Some amount of cupping is normal, but excessive cupping, or an increase in the amount of cupping over time, suggests glaucoma. There are many blood vessels that emerge from the optic disc to the retina.
Glaucoma causes loss of the neural reddish tissue and there is progressive cupping of the optic disc – enlargement of the whitish central part.
In the great majority of the cases, glaucoma occurs in susceptible individuals. This form of glaucoma is called “primary glaucoma” – it does not occur as a result of any other eye problem.
Glaucoma may also be caused by previous ocular trauma, associated systemic diseases, use of medications, consequence of complicated eye surgeries, and others. In these situations, the disease is called “secondary glaucoma”.
Nevertheless, in all cases, glaucoma occurs mainly due to a sufficiently high IOP leading to damage to the optic nerve. The critical IOP level in which optic nerve damage will occur varies among patients, and it depends upon many variables that will determine each patient´s susceptibility for the disease.
In other cases, IOP may be relatively normal, but glaucoma occurs anyway because of the inability of the eye to handle mechanical stress where the nerve fibers leave the eye or because of poor blood supply to these same nerve fibers.
So, glaucoma damage may occur within the normal IOP levels – normal levels for most of the individuals but not for all. In this situation, the glaucoma may be called “normal tension glaucoma”.
But as a main rule, the higher the IOP, the higher the risk for glaucoma development and progression.
The great majority of glaucoma cases evolve silently, as patients may not notice vision loss until it is significant and present in both eyes, or may assume that vision loss is correctable, as it is for other conditions such as cataract. When the disease is at advanced stages, most patients will then perceive visual abnormalities. Glaucomatous damage to the optic nerve is irreversible, so what is lost cannot be recovered.
The asymptomatic early stages of disease and irreversible nature of the glaucoma makes it one of the main causes of blindness worldwide. Glaucoma does not have a cure, however, this disease can be treated and the worsening of glaucomatous damage can be limited or even stopped. Thus, an early detection associated to an appropriate treatment and follow-up can preserve your vision throughout your lifetime.
The eye contains a fluid known as aqueous humor that provides nourishment to its structures. This fluid is produced by the ciliary body (located behind the iris) and then flows between the iris and lens, through the pupil to the anterior part of the iris where is drained out through a sieve like structure called the trabecular meshwork, at the anterior chamber angle (located at the merging of the cornea-sclera with the iris periphery).
Many (but not all) cases of glaucoma occur due to a sufficiently elevated IOP, caused by impairment of the normal aqueous humor drainage.
Glaucoma may be classified according to different aspects. Mainly:
Glaucoma may occur in babies due to abnormal development of the internal drainage system of the eye. Its signs and symptoms are usually different than adult glaucoma. Classical cases present with enlarged eyes, with a whitish-bluish cloudy appearance as the cornea becomes edematous due to the high IOP. The baby will present intense photophobia (intolerance to light), blepharospasm (i.e. keep eyes shut when exposed to sunlight), and excessive tearing (which may be present in other abnormalities such as nasolacrimal duct obstruction).
Congenital glaucoma is a sight-threatening disease, and a consultation with a glaucoma specialist should be arranged as soon as possible. Examination under anesthesia is required for appropriate assessment of the condition, and treatment is primarily surgical. Early diagnosis and proper treatment are important for a good visual prognosis.
Long-term follow-up is necessary, when the IOP and optic nerve will be monitored, but also, glasses and eye-patching might be necessary for the development and maintenance of a good vision.
Normally, glaucoma affects individuals after 40-50 years of age, but it may occur in younger ages.
Juvenile glaucoma affects teenagers or young adults and its signs and symptoms are very similar to adult glaucoma. However, juvenile glaucoma may be considered more visual threatening as IOP levels tend to be higher and also, as the disease onset is early in life, there is a need to preserve the optic nerve for a much longer period of time.
Therefore, although it is not a common disease, all individuals attending an ophthalmological check up should undergo IOP measurement and optic disc evaluation.
As in all forms of glaucoma, the end-organ damage is the optic nerve head. A sufficiently elevated IOP will damage the optic nerve, which is the structure that connects what the eyes see to the brain.
The “angle” is the part of the eye where the iris meets the cornea and the sclera. The drainage system of the eye is located at this region – trabecular meshwork, which consists of multiple layers of collagenous connective tissue. The trabecular beams form a net like structure that creates layers with large and small spaces within the beams.
The open angle glaucoma, as the term suggests, is characterized by an open angle. Nothing obstructs the flow of the aqueous humor to get to the trabecular meshwork, however, abnormalities within the spaces of the trabecular meshwork system lead to increase of the resistance to flow of fluid. The fluid pressure within the eye (IOP) gets elevated, and usually without any symptoms, gradually damages the optic nerve.
Increased IOP is the most important risk factor for glaucoma and, based on epidemiological studies, normal eye pressure varies from 10 mmHg to 21 mmHg in European populations. However the critical IOP level in which glaucoma damage occurs varies among individuals. This depends upon many anatomical/physiological variables that will determine each patient’s susceptibility for the disease.
For example, damage to the optic nerve may occur within the “normal” range IOP – a condition sometimes referred to as “Normal pressure glaucoma” or “Low tension glaucoma”. In most of the cases, patient’s individual characteristics (i.e. structure of the optic nerve head) determine an increased susceptibility to glaucomatous damage, which may occur within IOP levels that would not cause any harm for most individuals. Regardless of whether the IOP is high (i.e. above 21) or not, future glaucoma damage can be prevented by treatments which lower the IOP.
On the other hand, cases with elevated IOP (greater than 21 or 23 mmHg) without optic nerve damage may also occur, and this condition is called “Ocular hypertension”. In these cases, individual characteristics determine a decreased susceptibility to the disease.
This condition occurs in eyes with elevated IOP, without optic nerve damage. Due to individual characteristics that determine a decreased susceptibility to the disease, these eyes do not develop glaucoma. This may be partially explained in some cases due to an increased central corneal thickness (thick cornea), which may lead to imprecise measurement of the IOP by tonometer devices (overestimation of the IOP).
However, it is important to note that some eyes with elevated IOP may be simply at the beginning of the disease process, whereas there was not enough time to damage the optic nerve head. If this is the case, with time, glaucoma will develop.
The ophthalmologist will discuss with the patient the advantages and disadvantages of different management approaches for this condition in each case, including observation only or treatment.
In all Ocular Hypertension cases, continuous long-term follow-up are highly recommended, and some eye exams will be necessary for proper monitoring.
Glaucoma suspect is the term used for individuals in which glaucoma diagnosis cannot be confirmed but also cannot be excluded at the time of consultation. In these cases, a mid- or long-term follow-up associated with proper evaluation may be necessary to unveil the presence of disease.
Although this may be considered an uncomfortable situation, it is important to emphasize for the patient to remain calm, as the inability to establish the diagnosis usually occurs in early glaucoma cases and not in advanced cases in which the alterations are more evident.
The inability to confirm the diagnosis may be due to different causes.
The normal appearance of the optic nerve head shows wide variation in the normal population. And in some cases, it may be difficult to differentiate an early glaucomatous optic disc from an optic disc with an unusual appearance (but with no disease).
All individuals diagnosed as glaucoma suspects or with a positive family history of glaucoma should ideally perform proper documentation of the optic disc appearance and visual function status. These exams should be repeated periodically, in order to compare them for changes along mid and long-term follow-up. Along with other exams, determining the presence of deterioration of these variables with time will confirm (or not) the presence of disease.
The ophthalmologist will discuss with the patient the advantages and disadvantages of different management approaches for this condition. In all cases continuous long-term follow-up is highly recommended, and some eye exams are necessary for proper monitoring.
As in all forms of glaucoma, the end-organ damage is the optic nerve head. A sufficiently elevated IOP will damage the optic nerve, which is the structure that connects what the eyes see to the brain.
The “angle” is the part of the eye where the iris meets the cornea and the sclera. The drainage system of the eye is located at this region – trabecular meshwork. (See Open angle glaucoma.)
In primary angle closure glaucoma, the part of the angle where the trabecular meshwork is located is closed/obstructed by the peripheral iris. This angle closure leads to IOP rise and damage to the optic nerve. Angle closure glaucoma usually affects anatomically “small eyes” – in which intra-ocular structures within a limited space area results in a crowded anterior segment.
It typically affects more women than men, and although it may occur in any individual, it is more common in some ethnic groups (i.e. Chinese). Most of the cases are asymptomatic, but some show quite intense symptoms. (See Acute angle closure.)
The most common mechanism of angle closure is called pupillary block, and it occurs due to relative block of fluid flow at the level of the pupil (from the posterior to anterior part of the eye), which makes the pressure at the posterior chamber to increase, leading to a forward bowing of the iris and narrowing of the angle
Differentiation between an open angle and a closed angle glaucoma is important because the treatment approach differs, as we may use additional procedures to treat angle closure glaucoma when compared to open angle glaucoma cases.
There is a form of angle closure that is very aggressive and shows intense symptoms. In this condition, there is a sudden rise in pressure leading to severe eye pain (and around the eye), redness, decrease in vision. This is known as an acute attack of angle closure and represents a medical emergency, which, if not treated in time, can cause optic nerve damage and loss of vision.
Acute attack symptoms normally occur in one eye, but it may be present in both eyes at the same time. The duration of the symptoms is relatively long (hours), when both pain and decrease vision are often associated. The pupil is often mid-dilated, and the pupil reflex is unresponsive to light.
Episodes of isolated eye pain or isolated blurred vision (minutes) that resolve spontaneously are likely not an acute angle closure attack.
Treatment may include topical and systemic drugs to lower IOP, followed by laser treatment aimed to open the angle (See Laser peripheral iridotomy). In some cases, surgical procedures may also be used to treat this condition.
The “angle” is the part of the eye where the iris meets the cornea and sclera. The drainage system of the eye is located at this region – trabecular meshwork .
Angle closure glaucoma typically affects anatomically “small eyes” – in which intra-ocular structures result in a crowded anterior segment. In primary angle closure glaucoma, the clogging of the angle by the peripheral iris will lead to IOP rise and damage to the optic nerve (see Angle closure glaucoma).
The contact between the iris and the trabecular meshwork represents a risk factor for the development of the disease. In these cases, regardless of normal IOP values and/or normal optic disc appearance, treatment may be indicated to prevent the sequence of events that may lead to angle closure glaucoma. Occludable angle diagnosis, with no other ocular abnormalities, means that the detection has been made early in the disease process.
The most common mechanism of angle closure is called pupillary block, and it occurs due to relative block of fluid flow at the level of the pupil (from the posterior to anterior part of the eye), which causes forward bowing of the iris and narrowing of the angle (see Angle closure glaucoma).
The usual therapy to be considered in the treatment of angle closure is laser iridotomy. This procedure will create a new communication between the anterior and posterior chamber (through the iris), and it aims to resolve pupillary block mechanism, resolving the forward bowing of the iris and, in most of the cases, open the angle (see Laser peripheral iridotomy). Cataract surgery, or removal of the natural lens and replacement with a thinner artificial lens, can also help opening the angle.
This is an aggressive form of secondary angle closure glaucoma. It usually affects individuals with retinal disease, mainly retinal vascular occlusion or uncontrolled diabetic retinopathy. The primary abnormality is represented by the retinal ischemia, which releases angiogenic factors. These factors create new vessels at the anterior chamber, usually at the iris pupillary border and the angle wall. These new vessels are abnormal and fragile and will cause a series of events which will lead to secondary angle closure (drainage system obstruction).
The treatment strategy should aim at the primary abnormality (retinal ischemia) and also at the IOP control. This relatively complex form of glaucoma often requires the combined efforts of glaucoma and retina specialists. Diabetic patients should try to maintain as good control of their disease as possible.
Yes, glaucoma can be caused by several medications taken for other diseases, such as Parkinson, epilepsy, depression, allergies, prostate disorders, etc. These represent secondary glaucoma cases.
Particular attention should be given to corticosteroids. Steroid induced glaucoma is a type of glaucoma which develops with the use of medicines known as corticosteroids. It is most commonly noticed with steroid eye drops taken for allergic conjunctivitis/uveitis but can occur with use of steroid containing inhalers (taken by patients who suffer from asthma), nasal spray, skin ointments and any oral or IV medication containing steroids. Moreover, not only corticosteroids may cause glaucoma, but it may also lead to loss of IOP control in patients in treatment for glaucoma.
Thus steroids should be used cautiously and the patients who are using any form of steroid therapy must consult their ophthalmologist (eye specialist) and have their IOP checked regularly.
Of note, particularly for angle closure glaucoma, there are many medications that may trigger or contribute to the angle closure process. Drugs used for depression, migraine, urine incontinence, gastrointestinal disorders and other health conditions can worsen or cause a closed angle. Thus, patients with this form of the disease or suspect of having it should always mention it to their physicians, who will be able to evaluate which medications are safe or not. Also, patients with untreated angle closure or “occludable angles” should be careful when using some medications, even over the counter medications.
When an eye sustains an injury there can be an acute increase in IOP due to damage to the angle structures, hyphema (blood in anterior chamber), inflammation, and other mechanisms. The more severe the trauma, the greater are the chances to develop glaucoma and other ocular complications. But IOP increase may also occur later in life due to damage of the trabecular meshwork. This form of glaucoma can occur even up to 10-20 years after injury. These are also considered secondary glaucoma cases.
It is recommended that any person who has sustained an injury to the eye should get him/herself evaluated for glaucoma, and maintain regular follow-up with an ophthalmologist.
Glaucoma is known as the “silent thief of vision” and is typically associated with painless and progressive loss of vision that may not produce any symptoms. Usually, peripheral vision is affected with relative sparing of central vision at early stages of disease, and when the disease gets to advanced stages, the central vision is more severely affected. Glaucoma patients may notice that they cannot see objects at their side (due to loss of peripheral visual field), but largely the patients are not able to detect any symptoms until a very advanced stage. Sometimes, patients may notice or describe that their vision has become foggy (see How does glaucoma evolve?).
Angle-closure glaucoma may be associated with redness, pain in the eye, headache, blurred vision and coloured haloes around light bulbs – acute angle closure attack presenting with quite high IOP levels (above 40 mmHg). However, most angle closure glaucoma cases evolve asymptomatically, as the clogging of the drain and IOP rise tend to occur in a slowly progressive way (see Angle closure glaucoma).
Non-specific vision symptoms may also be associated with glaucoma, like cloudy/foggy vision, glare, or needing more light to read.
Although the normal pressure lies between 10-21 mmHg, even if your pressure is more than 21 mmHg you may not have glaucoma. A person is diagnosed to have glaucoma only if the optic nerve is damaged. In addition if your cornea is thicker, then the eye pressure may be over-estimated by the measuring instrument. If you have increased eye pressure but no damage to the optic nerve, you do not have glaucoma but you are at an increased risk for developing it, and should discuss management with your ophthalmologist.
This condition is known as ocular hypertension (see Ocular hypertension and Intraocular pressure).
Glaucoma is diagnosed by performing the following 4 essential tests:
In addition to these basic exams, additional tests that may be performed include:
A tonometer is an instrument that measures the IOP. This can be done by a contact or non-contact method. The contact method most commonly used is known as Goldmann applanation tonometry, which is the reference standard method to measure IOP. Other machines that may be used for recording IOP include: pneumotonometer, Tonopen, Rebound Tonometer, Perkin’s Tonometer and Schiotz Tonometer.
This is a painless procedure, and you can help your doctor obtain a more precise measurement by maintaining your forehead and chin stable at the slit-lamp, eyes wide open, try not to blink, and keep looking straight ahead.
This is usually performed on every consultation, and may also be performed multiple times in a single day, as IOP is a quite dynamic parameter, and do vary during different hours of the day, and along different days.
This is a painless procedure, and you can help your doctor obtain a better evaluation by maintaining your forehead and chin stable at the slit-lamp, eyes wide open, try to get used to the lens touching your cornea, try not to blink, and keep looking straight ahead.
Gonioscopy is the reference standard exam to evaluate the angle – where the drainage system of the eye is located. This exam requires placement of the patient at the slit lamp (a simple machine with an illumination and viewing system).
A bright light will be used to assess the appearance of the optic nerve head, and evaluate the presence of glaucomatous structural damage. It is a quick and painless procedure.
The optic nerve is examined at the slit lamp by using special lenses, usually with NO contact with the eye. The optic nerve or optic disc may also be evaluated by using an instrument known as the Direct Ophthalmoscope. The examiner views inside the eye by coming close to the patient with a portable device.
A photograph of the optic nerve may also be taken to keep a record and see any changes over time. The pupil may have to be dilated for this examination.
The automatic perimetry is the reference standard exam to assess visual function.
Basically you will press a button everytime you see a light stimulus presented at various locations of your visual field: some at central region, some at the periphery. Stimuli will be presented at different intensities, from very bright to very faint. It is important to keep your eyes still, fixated on a central target throughout the exam, and to just press the button when you do notice the stimulus.
It is a painless procedure, but it will take some minutes, and it can be considered as a burdensome and/or boring procedure. However, it is very important that you maintain your attention during the whole examination and perform this test in the best way possible, as the obtained information is essential to clinical management decisions. Thus, keep calm and focused, as this is not a pass or fail exam, it is just to check how your vision is doing to ensure appropriate treatment.
Glaucoma is associated with characteristic visual field loss, which has to be monitored at least once or twice a year to establish if there is any progression of disease. As a subjective exam, visual field results do vary/fluctuate, and repeating VF exams may be considered a common procedure to confirm glaucoma progression.
If you have been diagnosed with glaucoma you will require a 3-12 monthly follow up, depending on the severity of disease, the IOP levels under treatment, and other risk factors. The more severe the disease, the more frequent the follow-up. On the other hand, once the disease is well under control and there are no signs of progression, follow-up at longer intervals may suffice.
The bottom line is that the recommended interval between consultations may vary, and should be determined by your ophthalmologist. Of note, glaucoma patients will need follow-up visits for the entire life.
After the initial diagnosis, you will have to get the visual field test repeated to get a good baseline and then repeated more frequently in case the disease is advanced or if your pressure is not under adequate control.
After initial diagnosis, all individuals with glaucoma should perform proper documentation of the optic disc appearance and visual function status. Visual field tests often need to be repeated to get a good and consistent baseline. These exams should then be repeated periodically, in order to compare them for changes along mid and long-term follow-up.
Glaucoma treatment aims to control the intra-ocular pressure and halt glaucoma progression. It is important to understand that glaucoma cannot be cured and whatever damage has occurred to the optic nerve cannot be reversed. However, it is possible to maintain current vision (central and peripheral), so the patient will not develop further visual damage.
Various modalities of treatment are available today. These include:
Eyedrops are usually prescribed as the first line therapy for most types of glaucoma. It is essential to understand that glaucoma does not have a cure, so these drops should be taken on a regular basis, everyday, for your entire life. One of the most important factors in using eye drops for glaucoma is regularity over a long period of time. Consistent/Repetitive failure to comply with eyedrop treatment may result in poor glaucoma control and vision loss.
As a suggestion, you may plan out a schedule for taking your drops around your normal routine, such as when you wake up, brush your teeth, eat meals or when you go to bed at night. You may also set reminders in your cell phone. As a suggestion, after taking a dose, you can put a mark on the calendar so that you remember that you have taken the medicine.
Aim to put only one drop at a time, but if you are not sure the drop got into the eye, you may put an extra drop right away. To optimize eyedrop use, please check What is the correct way of instilling the eyedrops?.
It is recommended to keep a stock of your medication at home, and do not forget to take your eyedrops bottles with you while travelling. Before you visit your eye doctor for check up, always use your eyedrops as usual.
Eyedrops are medicines, and it may be contra-indicated in the presence of some other systemic/ocular diseases. Please remember to tell your doctor if you suffer from any other medical illness like asthma, arrhythmia, bradycardia, diabetes, hypertension, thyroid diseases, angina, arthritis, depression etc., or are taking oral medicines or inhalers for any other condition. The ophthalmologist is able to choose the best treatment strategy for each individual case.
One of the most important factors in using eye drops for glaucoma is regularity over a long period of time. Forgetting to put your eyedrops may happen once in a while, but consistent/repetitive failure to comply with eyedrop treatment may result in poor glaucoma control and vision loss.
If you forget to take a dose of your eye drops, it is best to instill the drop as soon as you remember it. If the next dose is due shortly, wait for the usual time to use it.
There are a number of medicines available for lowering the IOP in glaucoma patients. Since this is a life-long treatment, it is important to select eyedrops that do not disrupt patient’s quality of life.
Frequently used eye drops and their respective possible side effects are:
Latanoprost, Travoprost, Bimatoprost, Tafluprost
To be used as 1 drop- once a day at night. Of note, it can be used at daytime at the physician’s discretion.
Side effects: may cause redness of the eye (which may or may not resolve/fade in a few weeks), darkening of the color of iris (in light irides of mixed colors) and the skin surrounding the eyes, and it may cause fat reduction around the eye, leading to recession of the eyeball into the orbit. It can cause the eyelashes to grow darker and longer.
Timolol, Betaxolol, Levobunolol
Dose: one drop twice a day (like 7am – 7 pm). Some sustained release preparations are available that may be used only in a single morning dose.
Side Effects: Can worsen lung disease (like asthma, chronic obstructive airway disease), lower the blood pressure and heart rate, cause dizziness and insomnia and rarely depression, impotence and decrease libido. May inhibit symptoms of hypoglycemia in diabetics and alter the lipid profile.
Dose: To be used thrice a day if used alone and twice a day if combined with another glaucoma eye drop.
Side effects: may produce allergic reaction and itching in the eyes, and it may cause sleepiness and low blood pressure. It should be avoided in children (< 6 years) as it can cause excessive drowsiness and respiratory depression (breathing difficulty).
Brinzolamide ; Dorzolamide
Dose: To be used thrice a day if used alone and twice a day if combined with another glaucoma eye drop.
Side effects: Can cause stinging sensation in eyes and unpleasant taste in mouth. If IOP is very high, an oral medication (Acetazolamide) can also be given for a short time to control IOP, until the time laser or surgery is done.
Use of oral acetazolamide is associated with tingling, numbness, altered taste, indigestion, nausea, vomiting, skin rashes. Take food rich in potassium (orange juice, bananas, coconut water) to reduce side effects. In some cases, potassium tablets may be prescribed. Not to be used in patients with sickle cell disease (particularly for oral medication). As patients with sulfa allergy may get allergy from carbonic anhydrase inhibitors, please discuss this with your ophthalmologist.
Pilocarpine represents this class of drugs. It works by increasing outflow. It was a very popular drug in the past, but has been replaced nowadays by new compounds due to its side effects profile. It is still used in some clinical situations, such as angle closure glaucoma or pre-laser treatment.
Possible side effects may include: ocular pain, headache, small pupil (miosis), blurred vision, and diminished vision in dim light situations.
Systemic side effects are rare and include increase salivation and sweating.
There are products that combine two drugs in one bottle. This is very useful for patients that need two drugs to control the disease. The existing combinations include:
Fixed combinations are very popular, as many patients with glaucoma need at least two drugs to control the disease.
Dose: To be used up to 4 tablets per day.
Side effects: Use of oral acetazolamide is associated with tingling, numbness, altered taste, indigestion, nausea, vomiting, skin rashes. Take food rich in potassium (orange juice, bananas, coconut water) to reduce side effects. In some cases, potassium supplement tablets may be prescribed.
Contra-indicated: Not to be used in patients with sickle cell disease (particularly for oral medication). Not to be used/or used with caution in patients with poor renal function, or history of renal lithiasis (renal calculi) or gallbladder lithiasis (gallstones). As patients with sulfa allergy may get allergy from carbonic anhydrase inhibitors, please discuss this with your ophthalmologist.
Dose: usually to be a one time use for acute angle closure attack and other specific conditions for in hospital use.
Side effect: Use intravenous mannitol may pull water from the tissues into the vessels, and may cause many systemic side effects, such as dehydration headache, nausea, diarrhea, vomiting, dry mouth, thirst, blurred vision, vomiting, runny nose, arm pain, chills, dizziness, low blood pressure (hypotension), hives, irregular heart beat, electrolyte imbalance, etc.
Contra-indicated: Not to be used in patients with poor renal function, or poor cardiac function (congestive heart failure), and other specific systemic conditions.
Glycerol: also may be used for acute angle closure. Glycerol is an oral solution, and as mannitol, may also cause many systemic side effects. Particularly, this medication should be avoided by patients with Diabetes.
Laser is the treatment of choice for angle closure glaucoma and other types of laser may also be performed for open angle glaucoma. Lasers can be performed as an outpatient procedure in a few minutes and may be used to reduce the IOP.
The following types of laser procedures are generally used in glaucoma:
This procedure is often recommended in eyes with angle closure where a relative pupillary block prevents the flow of fluid from the posterior chamber into the anterior chamber (see Angle closure glaucoma).
Herein an opening is made in the iris with a laser machine for the fluid to drain from the posterior to the anterior chamber of the eye, bypassing the pupillary block. This procedure is done in eyes with narrow angle to prevent an angle closure attack and also as a treatment if the patient is having an acute attack.
This procedure uses laser to target the trabecular meshwork and aim to alter the pores/spaces in the trabecular meshwork and increase the outflow of aqueous (fluid) thereby decreasing IOP. This is done in open angle glaucoma eyes.
It is important to note that this procedure is not always effective, and it may work for a limited period of time (some years). When effective, the IOP lowering caused by laser trabeculoplasty is expected to produce a mild to moderate IOP lowering effect.
There are different lasers to perform trabeculoplasty, including “Argon or Selective trabeculoplasty”.
After the laser, the patient should maintain regular follow-up, and may still require eyedrops or surgery.
This laser procedure aims to decrease the aqueous production by treating part of the ciliary body epithelium (structure located behind the iris responsible to produce aqueous humor).
In most of the cases, this procedure is reserved for eyes with end stage glaucoma, that have elevated IOP despite conventional medical and/or multiple surgical treatment. It is also performed in painful blind eyes. This restricted indication is due to the possibility of hypotony (low eye pressure) and globe atrophy.
New approaches of this technique are under evaluation to be performed in eyes with less severe stages of glaucoma, particularly those using endoscopic techniques (endocyclophotocoagulation) or new laser devices (micropulse).
The failure of medications and laser surgery to control the intraocular pressure (IOP) and consequently glaucomatous neuropathy, is an indication for surgery. Surgery may also be performed if the patient has allergy to the drugs, is not compliant to therapy or the disease continues to progress despite treatment. Advanced disease and other conditions are also indication for surgery and the ophthalmologist will discuss the best possible treatment options with the patient.
In traditional glaucoma surgery, a small guarded hole (fistula) is made to drain out fluid from inside the eye, thereby reducing the IOP. This is the most common surgery performed for glaucoma, and is known as trabeculectomy.
In this technique, a tiny guarded hole in the wall of the eyeball at the level of the junction of the cornea and the sclera is performed to allow the egress of the aqueous humor through a new alternative outflow way. The aqueous humor is directed through the tiny hole to a reservoir at the sub-Tenon/sub-conjunctival space that is called filtering bleb. The sutures aim to control the amount of flow, and from bleb, the aqueous is then absorbed through the capillaries to the blood circulation. Surgery is usually done under the superior eyelid.
After surgery, a small white coloured blister / scar can be seen in the upper part of the eye and is called a “bleb”. In most cases, the bleb remains covered by the superior eyelid and cannot be seen unless the eyelid is retracted.
Trabeculectomy surgery may lead to several and some serious complications, like loss of vision, cataract, infection, mild ptosis (droopy eyelids), discomfort, etc.
The healing nature of the human organism will try to close the trabeculectomy hole or fistula. The ophthalmologist will work to modulate the scarring process and maintain the drainage through the fistula for the longest period possible. The post-operative period is of outmost importance to minimize complications and failure of the procedure, and the patient needs to be on constant follow up with the operating surgeon, at least in the early postoperative follow-up period.
Nevertheless, this surgery may remain comfortable/asymptomatic for the patient, and effective in lowering IOP for a long time. Success depends on several factors, including the patient’s age, glaucoma type, time of use of topical medications, previous surgical procedures, etc. Your ophthalmologist will discuss your probability of success.
If at any time after surgery the patient notices an increased redness, pain, sensitivity to light and loss of vision – he/she should report immediately to an eye specialist as this can be an infection in the eye. Although not frequent, any infection inside the eye (endophthalmitis) can lead to irreversible visual loss if not treated urgently. Antibiotic use should start as soon as possible, and other treatments (injections of medicines, surgery) may be required for more advanced infections.
Bacterial conjunctivitis is characterized by conjunctival yellow-green discharged, particularly when awakening. In eyes that underwent trabeculectomy, although uncommon, the infection may spread to inside the bleb and inside the eye. Prompt treatment of conjunctivitis with topical antibiotics is important to prevent this serious potential complication.
Other types of surgery include Drainage implant surgery – these implants consist of a silicon tube, which is connected to a draining plate. The tube is inserted in the eye and the drainage plate is sutured to sclera. The intraocular fluid gets collected in the plate, under the conjunctiva, and gets absorbed by the surrounding tissues.
Some of the possible complications include corneal decompensation and tube erosion through the conjunctiva. If this last situation occurs, patients should seek medical care as soon as possible.
Many new micro-surgical techniques for glaucoma, often referred to as MIGS (Minimally Invasive Glaucoma Surgery) are now available in several parts of the world and may be useful for the individual patient depending on the type of disease and its severity. Some of these new techniques include devices such as the Istent, CyPass, Hydrus, Xen etc. These new devices are still under critical evaluation and the long-term results are still not available.
Recently, in 2018, one of these new devices (Cypass) was removed from the market (withdrawn) voluntarily by its manufacturer as post-approval study showed that some patients who have this device implanted into the eye may be at risk of losing corneal cells. Further investigation will be performed to determine its safety profile, and if this new device will return to the market in the future.
This episode shows an example of how regulatory agencies, manufacturers, doctors and patients around the world should be continuously attentive for the risks/benefits of the different therapeutic procedures, particularly the new ones.
Cataract is an opacity in the lens or its capsule that normally occurs with aging, and it may eventually lead to visual impairment. Glaucoma and cataract can both co-exist in the same eye. Visually impairing cataracts are treated by surgery, which will remove the opaque lens and replace it with an artificial lens. If there are no other abnormalities, vision is fully recovered after surgery.
Patients with glaucoma should undergo a comprehensive individualized assessment to determine the best surgical strategy. Advanced glaucoma or IOP poorly controlled by medical/laser treatment should be evaluated for combined glaucoma/cataract surgery.
Of note, glaucoma can occur secondary to abnormalities of the lens, such as dislocated or subluxated lens from its normal position (Phacotopic glaucoma); when lens becomes opaque and swells up (Phacomorphic glaucoma); when the cataract has become mature there can also be micro leaks from the capsule of lens and this can induce glaucoma by inflammation or lens protein deposition in trabecular meshwork (phacolytic and lens protein induced glaucoma).
The presence of a large lens in a small crowded eye, or a more anteriorly located lens may represent relevant mechanisms for primary angle closure.
No. Unfortunately glaucoma medicines, laser or surgery cannot improve your vision but can prevent you from further visual loss.
Can stem cell transplant be done to repair the damaged optic nerve in glaucoma? This is an area of experimental research and until now this treatment is not possible/available for glaucoma patients. However, there are several research groups working on this topic at this moment, and the effectiveness of the stem cell transplant may be available in a few years.
Patients with glaucoma often inquire about their eligibility to undergo refractive surgery, such as LASIK or PRK, among others.
Although there is no consensus on the specifics of who should or should not undergo refractive surgery, many doctors agree that patients with severe glaucoma should avoid these procedures. Also, refractive surgery can make eye pressure measurements more difficult to interpret.
For those who do not have a glaucoma diagnosis, we recommend visiting a glaucoma specialist before the procedure if you have positive family history of glaucoma (particularly cases of blindness in the family), if you are considered a ‘glaucoma suspect’, or have a combination of risk factors for the disease (see Who should be checked for glaucoma?).
Glaucoma patients with visual field defects are at increased risk for motor vehicle accidents. Although central vision is usually spared up to late phases of the disease, glaucoma may affect the peripheral vision at early to moderate phases. Glaucoma patients usually complain about glare, poor night vision and low contrast sensitivity. Also, vision can occasionally become very poor when transitioning from light to dark (i.e. when entering a tunnel).
It is recommended for glaucoma patients with moderate-advanced visual field loss to avoid or even stop driving, particularly in more difficult situation such as at night and under fog conditions. Public transportation should be used as often as possible. You must consult your doctor to discuss this issue and study your state authority regulations for driving.
It is important to understand that any eye drop used for glaucoma by the mother can get absorbed into the circulation and it may affect the fetus; also some medicines are secreted in breast milk for nursing mothers. There is risk to the fetus with all glaucoma medications – especially in the first trimester of pregnancy. If you have glaucoma and are planning to start a family, please have a consultation with your eye doctor and physician to discuss this issue.
Patients who have lost vision progressively due to glaucoma will be under great psychological stress, and caring to the needs of the patient may be challenging both to the doctor and family members. The family can help in multiple ways:
After a proper assessment by an eye-care professional, specially qualified in providing low vision services, the following aids can be advised to the patient:
It is important for you to get yourself regularly screened for glaucoma. If you have been diagnosed to have glaucoma, effective treatment options are now available and regular treatment and follow up can help you to preserve your vision for your lifetime, avoiding unnecessary fear of going blind.
You can live happily with glaucoma and enjoy an excellent quality of life, particularly if the disease is detected early and treated in time. Always remember that once you have glaucoma, you will have to be under the care of an eye doctor for the rest of your life.
There is a lot of research going on and new treatments may become available for glaucoma in the near future.