Glaucoma Surgery and Reducing Intraocular Pressure

 Glaucoma can be divided into two groups, open angle glaucoma and closed angle glaucoma. It is good to know that the part of the eye between the iris (the colored part of the eye) and the cornea (the transparent part) is called the angle of the eye. Typically, a clear fluid circulates in the front part of the eye. It is produced in the eye and flows out from the angle of the eye. If this angle is blocked or damaged, the fluid would not be able to flow out of the eye which results in an increased intraocular pressure and causes glaucoma.

In most cases, patients develop open angle glaucoma. However, a significant percent of patients also suffer from angle-closure.

Glaucoma Symptoms

Symptoms vary depending on the type of glaucoma:

1. Congenital glaucoma (infantile glaucoma): It appears with symptoms such as cloudy cornea, tearing, light sensitivity and the enlargement of the eye.
2. Open-angle glaucoma: In most cases of chronic open-angle glaucoma (and also angle-closure glaucoma), patients are not aware of glaucoma, until it advances and leads to visual field defects.

In most cases, comprehensive clinical exams, including the measurement of intraocular pressure, examination of the angle of the eye, checking the appearance of the optic nerve, and visual field tests are enough to diagnose glaucoma. However, in some cases, other tests such as retinal and optic disc photography are also required.

Glaucoma Treatment

During the progression of glaucoma, the optic nerve gradually deteriorates and nerve cells die slowly. In case of being diagnosed with glaucoma, there is no cure for the loss of optic nerve fibers at present. The main goal of glaucoma treatment is to prevent the progression of the disease and to preserve the remaining vision so that the patient can do his/her routine activities.

Glaucoma is treated using a stepwise approach. It begins with medications and if not successful, laser therapy is performed to reduce intraocular pressure. In the acute cases, when laser therapy doesn’t work either, glaucoma surgery will be performed.

Medical Therapy

The most common type of initial glaucoma treatment is medication. Glaucoma medicines are prescription eye drops and pills. These medicines reduce the intraocular pressure in two ways. Some of them reduce aqueous humor production, and some increase its outflow from the eye.

Trabeculectomy: It’s the most common non-laser surgical procedure which is performed to control the eye pressure if using eye drops, pills and trabeculoplasty is not successful.

Trabeculectomy creates a controlled drainage canal for aqueous humor to flow to the space under the conjunctiva. A blister-shaped flap is made at the border of the cornea and the sclera (aka corneal limbus) after the operation, in which the canal through which the fluid of the eye outflows into the space under conjunctiva will be created.

Non-penetrating Glaucoma Surgery (Deep Sclerectomy) and Viscocanalostomy: Both of these procedures are less invasive than filtration surgeries during which the posterior chamber will remain intact. In these two surgical procedures, a deep flap is created in the sclera (the outer white layer of the eye), and another one between the superficial and deeper parts of the sclera which acts as a reservoir for vitreous body. During viscocanalostomy, the surgeon injects a gel-like substance into the Schlemm’s canal to dilate it.

Trabeculotomy: This method is somehow similar to trabeculectomy, in which a piece of the tissue in the eye’s drainage angle is removed to create an opening to enhance the outflow of fluid. Trabeculotomy is usually used to treat congenital glaucoma when the cornea is cloudy. This procedure, as well as goniotomy, is proper for treating children because they are both less invasive.

Goniotomy: In this surgical technique the doctor uses a special lens called goniolens to have a view of the angle of the eye. This method is used to treat congenital glaucoma when the cornea is not cloudy. During this treatment process, a hole is created in the trabecular meshwork (a set of fine tubes located in the drainage angle of the eye) which ultimately enhances the drainage of aqueous humor.

Implanting Shunts: Aqueous shunts are small plastic canals or tubes on one side connected to a reservoir which is a rounded or oval plate. The shunt acts as an artificial drainage system and is placed in the eye through a small incision. The shunt accumulates the aqueous humor in a place under the conjunctiva (a fine layer covering the inner part of the eyelids and white part of the eye). The aqueous humor is finally absorbed by the blood vessels.

Our ophthalmologists in Iran-Tehran Noor Eye Hospital will provide you with additional information on this treatment.

1. The night before the surgery, take a bath and wash your face with diluted baby shampoo or soap.

2. Observe nutritional considerations according to the time of surgery given to the patient by the team.

3. If you are taking any specific medicine, be sure to inform your ophthalmologist and anesthesiologist.

Notes:

• Anti-hypertensive and Lipid-lowering drugs should be taken based on previous instructions.

• Heart medications should be taken based on previous instructions. In case of taking aspirin and warfarin, taking them should be stopped if possible. However, be sure to consult your doctor in this regard.

• Inform your ophthalmologist in case of having diabetes.

4. Be ready for pre-operative examinations including blood tests and cardiovascular consultation.

1. After being discharged, your eye will be dressed and covered by a plastic shield. Avoid taking off the dressing at home.

2. Plan to rest on the first day after the surgery. After glaucoma surgery, avoid lifting heavy objects (typically heavier than 2kg). If you have to climb the stairs, caution is advised as well as having a family member as companion by your side.

3. While resting, keep your head more elevated than usual.

4. Having light foods, hot liquids, vegetables and fruits is good to facilitate recovery.

5. After glaucoma surgeries, experiencing foreign body sensation is normal. Painkillers are prescribed to reduce the patient's discomfort.

Notes:

- The patient should undergo a follow-up visit one day after the surgery.

- Glaucoma surgery will help preserve vision and prevent blindness. It does not improve vision.

Q: From what age will glaucoma be important?

Q: What are the causes of glaucoma?

Q: How do I know if I have glaucoma?

Q: What clinical examinations are performed to diagnose glaucoma?

Q: When is the surgery to be performed to lower intraocular pressure?

Q: What are the differences between trabeculotomy and trabeculectomy?

Q: Which procedure is more proper to treat congenital glaucoma?

Q: How do aqueous shunts work?

Q: From what age will glaucoma be important?

A: From the age of 40, glaucoma would be important in normal people, and ophthalmic examinations should be performed regularly in Tehran Noor Eye Hospital in Iran.

Q: What are the causes of glaucoma?

A: The main causes of developing glaucoma are hereditary and genetic factors. However, according to physicians, taking some migraine drugs and the long-term use of corticosteroids through oral routes, injection, transdermal routes, inhalation, and especially eye drops, which are commonly prescribed for treating eye allergies, can also cause glaucoma in people more prone to develop it.

Additionally, cardiovascular diseases, diabetes, tranquilizers and antihistamines can cause this condition.

Q: How do I know if I have glaucoma?

• In congenital glaucoma, it’s associated with symptoms such as cloudy cornea, tearing, sensitivity to light and eye enlargement.
• In acute closure-angle glaucoma, the patient encounters severe symptoms such as reduced vision, tearing, photophobia, seeing halos and rainbows around lights, nausea and vomiting, and should be treated immediately.

Q: What clinical examinations are performed to diagnose glaucoma?

A: Measuring intraocular pressure, examining the angle of the eye, checking the appearance of the optic nerve, and visual field tests. However, if necessary, retinal and optic disc photography may also be ordered by ophthalmologist in Tehran Noor Eye Hospital in Iran.

Q: When is the surgery to be performed to lower intraocular pressure?

A: The surgery to lower intraocular pressure should be performed when the disease is not controlled by medication or it is not possible to use laser procedures in order to lower intraocular pressure.

Q: What are the differences between trabeculotomy and trabeculectomy?

A: They are somewhat similar to each other and in both of them, a part of the tissue of the drainage angle is removed, which creates a pathway to enhance fluid outflow. Trabeculotomy is commonly used to treat congenital glaucoma when the cornea is cloudy.

Q: Which procedure is more proper to treat congenital glaucoma?

A: Goniotomy is a procedure performed by ophthalmic surgeons in Tehran Noor Eye Hospital in Iran, during which a special lens known as goniolens is used to provide a view of angle of the eye. This method is used to treat congenital glaucoma when the cornea is not cloudy.

Q: How do aqueous shunts work?

A: These shunts accumulate the aqueous humor in a space under the conjunctiva. Finally, the aqueous humor is absorbed by blood vessels.