Glaucoma

Glaucomas are a group of eye diseases that damage the optic nerve in the eye. It causes an increase in the pressure inside the eyes leading to optic nerve damage.

After cataracts, glaucomas are the second most common cause of vision loss. It affects people of all age groups, including the newborns and the elderly. Your risk of it will increase with age.

The chamber inside your eyes between the lens and the cornea contains a clear fluid called aqueous humor. Its function is to nourish the various structures inside it and remove any waste products. It drains out of the eyes through an area called the 'angle.' Blocks in the 'angle 'can cause the fluid to build-up in the eyes to increase pressure.

In some, there is no real cause for this to happen. Such glaucomas are primary glaucomas.

Secondary glaucomas occur due to some diseases. You are more likely to have it if you have diabetes, hypertension, etc. Some other conditions or injuries to the eyes can also be a cause. 

In most, there will few early signs and symptoms. Pain in the eyes and blurring of vision will happen in some. As it progresses, one will have partial loss of sight. It usually affects peripheral or side vision in the early stages. Gradually, there will be a total loss in vision if not treated early on.

There is no cure to glaucoma, and treatments aim to control it. You will have treatments to reduce the pressure in the eyes. Medicines to decrease the production of fluid can help some. If the condition worsens, one will need surgery to open the 'angle' to allow the liquid to flow out. 

Laser surgery is a non-invasive technique to treat glaucoma. Some may need surgery to open the angle. Treating glaucoma in the early stages can help it from causing severe vision problems.

What causes Glaucoma? 

Glaucomas occur when there is an increase in pressure in your eyes. The pressure inside the eyes is called Intra-Ocular Pressure or IOP. 

Inside your eyes is a small chamber that lies between the cornea and the eyewall. It contains a fluid called the aqueous humor. It forms in the ciliary body that lies behind the iris. It flows into the chamber through an opening in the middle of the iris. 

The main functions of aqueous humor are to

• Nourish the tissues in the eyes 
• Remove any waste products that form in the eye
• Maintain the shape of the eyeball

It flows out of the chamber through an area called the drainage angle that is present between the iris and cornea. The angle has a kind of mesh that allows the fluid to flow out. The fluid moves into the sclera or the white of the eye. The blood vessels there then absorb the fluid.

Any block in the drainage of fluid will increase the IOP. It then will put pressure on the optic nerve to damage it and cause glaucoma.In some, glaucoma will occur even if the IOP is normal. The reason could be a very sensitive optic nerve that can not withstand normal pressure.

Glaucoma risk factors

Your chances of getting glaucoma will be more if you have any risk factors. The common ones are

• Getting old- Your risk increases with age
• Having family members with glaucoma- It usually runs in families
• Having short sight, long sight, etc
• A previous eye injury
• Having diabetes, hypertension, arrhythmias, etc
• Having uveitis, a swelling in the eyewall
• Having a sensitive optic nerve
• Having a thin cornea

Common types of glaucomas

There are two main types of glaucomas

1. Primary glaucomas where the cause is not clear
2. Secondary glaucomas that occur as a result of some diseases

Types of Primary glaucomas

Open-Angle Glaucoma:

It accounts for almost 90% of all cases. In this, the angle that drains the fluid is open. But, the amount of fluid that flows out through it is less. It causes the pressure to rise and damage the optic nerve. The first sign is the loss of peripheral or side vision. Slowly the angle of vision gets narrow, and you will only be able to see things that are straight ahead(Tunnel vision). If it progresses, there will be a total loss of sight.

You will not have any signs in the early stages that make it difficult to detect. High blood pressure could be a factor.

Normal-tension glaucoma

It is a type of open-angle glaucoma. In this, the pressure is normal, but one may have an optic nerve that is sensitive to pressure. You are more likely to have it if

• You have a family history
• Have arrhythmias
• You have low BP
• Treatments to decrease the pressure will help to control it

Angle-closure glaucoma

It occurs when an edge of the iris blocks the angle through which the fluids drain. It results in a build-up of fluid very fast, raising the pressure in the eyes. 

The common symptoms are

• Severe eye pain
• Feeling nausea
• Redness of the eyes
• Blurring of vision
• Loss of vision

You need to treat this very fast, or loss of sight will happen in a few days. Doctors will use lasers to remove the block to allow the fluid to drain out.

Congenital glaucoma

These are glaucomas that occur at the time of birth. The common signs are

• Cloudy eyes
• Teary eyes
• Sensitivity to light
• Bigger than normal eyes 

Treatment in the early stages can cure it and prevent any further problems.

Secondary glaucomas

Neovascular glaucomas

It happens when new blood vessels form in the angle that drains the fluids. These block the fluid from flowing out. You are likely to have this if you have diabetes or hypertension. The common symptoms are

• Eye pain
• Redness of the eyes
• A gradual loss of vision

You will need treatments to control the disease that caused it and also to lower the eye pressure.

Pigmentary glaucoma

The iris in your eyes has a lot of pigments that give it color. At times flakes of these can get loose and block the angle. The symptoms are

• Blurring of vision
• Seeing rainbow rings around lights

Young persons are more likely to have this problem. The symptoms usually get worse with exercise. Treatments aim to reduce the pressure in the eyes. But in some, the problem can happen again, and no treatment can prevent this.

Exfoliation glaucoma

You will have this when some proteins in the eyes break off and block the angle. It prevents the fluid from draining out to increase your eye pressure. The common signs are

• Higher eye pressure
• Sudden changes in eye pressure
• A gradual loss of side vision

You are more likely to have this if you are more than fifty and have a family history. You will need laser treatment or surgery to treat this.

Uveitic glaucoma

Uveitis is a type of inflammation in the uvea, a part of the eyewall. In some, it leads to scars that block the angle to prevent fluid drainage. It increases eye pressure to cause glaucoma.

The common signs are

• Eye pain
• Blurry vision
• Sensitivity to light
• Seeing 'halo's around light
• Frequent headaches

Your treatment will have two steps. Treating the uveitis and its cause is the first step. The next is to reduce the pressure in the eyes.

Glaucoma Diagnosis

Some of the common tests to detect glaucoma are

• Tonometry - It helps to measure the Intra-ocular pressure [IOP]. Normal IOP is around 15mm of Hg, and ideally, it should be below 21. Anything above 30 is very dangerous.
• Visual field testing- It helps to assess the extent of vision loss.
• Gonioscopy - A test to know the level of blockage in the angle

Some of the more advanced methods include

• Scanning laser polarimetry (SLP), 
• Optical coherence tomography (OCT)
• Confocal scanning laser ophthalmoscopy 

Glaucoma Treatments

Your glaucoma treatment will depend on the severity of your symptoms and the level of IOP.

Medicines

If you have few symptoms, you will have drugs. The medicines help to control the symptoms by 

• Help relax the eye muscles to make the angle wider
• Reduce the formation of new aqueous humor
• Increase the drainage of fluid

If medicines do not help you, the doctor will suggest surgery to remove the block.

Glaucoma surgery

You may any of the following depending on your condition.

• Trabeculectomy-a s procedure to increase the amount of the fluid that flows out. The surgeon will cut trabecular meshwork to improve the drainage
• Trabeculotomy -A procedure to reshape the trabecular meshwork
• Goniotomy- It is a good option for children with glaucoma. The surgeon will make a small cut in the front portion of the trabecular meshwork. It will increase the drainage of the fluid.
• Iridectomy-A procedure where the surgeon will make a small cut in the iris .t helps relive the IOP and bring it to normal levels
• Glaucoma Shunts-In this, the surgeon will make an alternate channel for the aqueous humor to flow out. The channel bypass the meshwork.

Laser surgery for glaucoma

The most common laser surgeries for glaucoma are-

• Selective Laser Trabeculoplasty (SLT)- You will have this for primary open-angle glaucoma. The surgeon will make a small cut in the meshwork with the help of lasers. It helps to improve the drainage of fluid.
• Argon Laser Trabeculoplasty (ALT)- You will have this for open-angle glaucoma.
• Laser Peripheral Iridotomy (LPI)- You will have this if you have narrow-angle glaucoma. The surgeon will make an opening in the iris to relieve pressure.
• Laser Cyclophotocoagulation- It aims to decrease the production of aqueous humor with lasers.

You can have Laser surgery as an outpatient procedure. Your recovery will be faster as there are no incisions.