Glaucoma
The human eye can be compared to a camera. The retina of the eye is analogous to the film inside the camera which captures a picture. The picture so captured is carried to the brain by the optic nerve. Glaucoma is a disease of the optic nerve caused by an increase in the intra-ocular pressure (Pressure inside the eye). This is characterised by a gradual progressive loss of neurons causing a progressive constriction of visual fields.
Types of glaucoma
Open angle glaucoma (POAG)
There is no functional block to the flow of fluid inside the eye (aqueous humour)
Angle closure glaucoma (PACG)
There is a block in the flow of fluid (aqueous humour) in the eye at the level of the pupil
Developmental glaucoma
Occurs from birth and is hereditary. Visual prognosis is guarded. These patients usually need multiple medications & surgery
Secondary glaucoma
Can be due to
- Trauma
- Following surgeries of the anterior or posterior segment
- Following chronic inflammation
- Prolonged use of steroids
- Long standing diabetes, retinal vessel occlusions
Symptoms
Patient with glaucoma may not have any symptoms. Hence the difficulty in explaining the importance of compliance to medications in these patients.
Some patients may complain of
- Frequent change of glasses
- Loss of field of vision (Fig.6.1)
Patient with angle closure glaucoma may complain of recurrent attacks of
- Redness
- Pain
- Blurred vision
- Coloured haloes
- Headache, vomiting
Parents of children with congenital glaucoma complain of
- Child avoiding light
- Increase in the size of the eyes
- Squinting of eye
- Increase tearing from the eye
Investigations
These are important for early diagnosis of the disease and also in follow up to prevent out progression of the disease.
Visual field testing
This analyses the field of vision of the patient. Ideally should be repeated every year or once in a month to rule out progression of the disease. The patient has to understand and cooperate with the test for it to be useful.
Central corneal thickness
The intra-ocular pressure measured by applanation can vary with any change in the thickness of the cornea. So CCT is measured in all patients with glaucoma.
OCT
This is to diagnose early glaucoma at a stage when it cannot be diagnosed by routine field tests and involves scanning of the nerve fibre layer around the optic disc.
SWAP
This is a modified field test which uses coloured stimulus. Also helps in diagnosing early glaucoma.
UBM
A technique to scan the anterior part of the eye to rule out structural abnormalities.
Role of the counsellor
To explain to the patient why specific investigations are essential and why they have to be repeated to rule out progression of the disease.
Treatment
Medication
The main concern in glaucoma counselling is ensuring compliance to medications.
Counsellor’s role: The counsellor should be able to communicate importance of using medications to bring down the IOP and that medications only preserve his vision from not deteriorating further. They are unlikely to improve it from the present stage.
She should try to ensure the support of the family in prolonged treatment.
It helps to allot specific times for the medications to be instilled.
Most of the medications have no serious side effects. However, they may cause worsening of asthma, allergy, redness of eyes etc. The cousellor can also demonstrate the correct method for instillation of medications.
Method of instillation of medications
Wash your hands before handling the bottle. Pull down the lower lid of the eye to create a pouch. Put a single drop of medicine and close the lids for 3 minutes without squeezing the eyes to reduce systemic absorption and enhance ocular penetration of the medicine. When using more than one medicine leave a gap of at least 10 minutes between them.
Expensive medications can preferably be instilled by an attendar to avoid wastage.
Some drugs may need to be kept in the fridge.
Lasers
Yag peripheral iridotomy
A small opening is made in the iris to bypass the block at the level of the pupil.
In-patients who have already developed angle closure glaucoma this relieves pain and brings down IOP. In primary angle closure glaucoma suspects this is done as a preventive measure to prevent future rise in IOP and allow dilated fundus examination. The procedure does not need hospital admission. The patient has to use topical drops for an hour. The laser procedure itself takes less than 10 minutes. Patients can continue all normal activities post laser.
Counsellors’ role
To make patients in pain comfortable and reduce the waiting period for treatment when possible. Explain the nature of the disease and necessity of PI in patients advised prophylactic laser PI. Patient should be informed that a repeat sitting may be necessary in some cases and it causes no harm to the eye.
Laser suturelysis
At the time of glaucoma surgery 1 to 3 sutures are placed in the eye. On follow up if necessary one or more of these sutures are lysed using yag laser. In the first 2 to 3 months period following glaucoma surgery, patients might need frequent followup to decide on suture lysis.
Counsellors’ role
To explain to the patient that though cataract surgery may be sutureless, glaucoma surgery involves 1-3 sutures. Removal of this suture is done by a laser beam and is painless. This helps to further bring down intraocular pressure.
Laser trabeculoplasty
Helps to further bring down the IOP.
Diode CPC
A minor laser procedure done under local anaesthesia. It does not improve the vision of the eye. It brings down IOP by partially destroying the structures that produce the fluid inside the eye. It is done in eyes with poor visual prognosis and when all other measures have failed.
Counsellors’ role
To communicate to the patient that the procedure will help to provide pain relief. It cannot give back lost vision.
Surgery
1.Trabeculectomy
A minor surgery, done under local anesthesia to bring down the intraocular pressure and thereby protect the optic nerve from further damage.
Counsellors’ role
To communicate to the patient that trabeclectomy does not improve the vision of the patient, but maintains it as it is. In very few patients there is even a chance for a mild decrease in vision. Following the surgery there might be a small scar in the white of the eye superior to the cornea.
Cataract surgery
The clouded lens in the eye is removed and replaced with an IOL. Can be done under local or topical anaesthesia.
Counsellors’ role
Explain the wide variety of IOLs and surgical options available for the patient.
Combined surgeries
If a patient who needs glaucoma surgery also has operable cataract, the surgeries can be combined.
Though cataract surgery may be sutureless glaucoma surgery involves 3 sutures and more frequent follow up.
Surgery under guarded visual prognosis
Patients with advanced glaucoma and high intraocular pressures may have poor visual prognosis
- Due to the already damaged state of the optic nerve
- Due to the higher rate of complications due to raised IOP
Counsellor should be able to thoroughly communicate this to the patient so that he has realistic expectations regarding the surgery.
Role of counsellor
Chronic glaucoma
- Primary open angle glaucoma (POAG)
- Secondary glaucoma
- Glaucoma suspect
- The counsellor explains the nature of the disease, the slow nature of visual loss and symptomless silent damage that it involves.
- The counsellor stresses the importance of regular follow-up and use of medication known to the patient
- The counsellor explains the unique characteristics of glaucoma
- Drops are the first line of treatment that should be continued life long
- The disease may progress despite regular use of medications
- Medicines only slow down the progress of the disease
- Certain types of glaucoma are familial and hence close relatives also need to be examined for the same
- Surgery may be required at some point of the disease and has to be decided by the doctor
- Loss of vision or visual field in glaucoma cannot be recovered. It is permanent
Acute glaucoma
- Primary Angle Closure Glaucoma (PACG)
- Neovascular Glaucoma (NVG)
- Absolute glaucoma, Malignant Glaucoma
- The counsellor may have to talk to a patient in pain, in certain stages of acute glaucoma. She can explain that the condition is treatable and everything is being done (ie. Drops, laser etc.) to relieve their symptoms.
- She must explain that the condition is recurrent, and that preventive measures like a laser may have to be done in both eyes to stop future attacks.
- Surgery may have to be done at later stage and will be decided by the doctor.
Congenital glaucoma
- The role of the counsellor is in making the parents understand that their child is suffering from a serious eye condition that is present from birth or developing early in life. The child may require surgery even when very young.
- The parents are made to realise that despite surgery and drops the child may have poor vision, but that the treatment is essential to prevent further damage.
- The need for repeated follow up and long term treatment, needs to be emphasised to the parents.
Frequently asked questions
1. Is the disease hereditary?
Yes, (Except for secondary glaucoma). It is important to screen family members to rule out glaucoma (siblings, children, parents)
2. How long should I use medications?
To preserve the present status of vision, medications have to be continued life long.
3. Will I have to continue medications even after glaucoma surgery?
The need for expensive medications comes down after glaucoma surgery. One medication though might have to be continued in some patients.
4. What is absolute glaucoma? Can’t I have a lens placed in the eye to regain my vision?
Absolute glaucoma is the end stage of glaucoma where the optic nerve has undergone total atrophy due to the raised IOP. Patient does not even perceive light. Since the optic nerve is totally destroyed placing an IOL in the eye does not improve the vision. Treatment at this stage is only for pain relief.
5. Can’t you replace my eye?
An eye in totality can not be replaced. Only the cornea of the eye can be replaced. Since the disease is at the level of the optic nerve this does not help in glaucoma.
6. Even if I don’t use medicines for 2 – 3 weeks, I am fine. Why should I continue medications?
Glaucoma is a very slow disease affecting the optic nerve. Our aim is to prevent visual loss over the years to come which is possible only by strict adherence to medications.
7. Will YAG PI harm my eye? Can I have head bath?
Usually it causes no problem to the eye. You might experience mild headache or photophobia for 2-3 days.Yes you can have bath since it is a non-invasive procedure.
8. Even after successful combined surgery, my side vision is poor why?
Surgery is to bring down the IOP and to replace the cataractous lens. The optic nerve damage that has already occurred cannot be corrected by this procedure. Hence, we should not expect any improvement on the side vision.
9. Even after using expensive medications for many years my vision has not improved, why?
Vision lost due to optic nerve damage cannot be regained. We can only aim to preserve the residual vision by preventing further damage.
Key points to remember
- Glaucoma is the term used to indicate changes in optic nerve head and visual field changes associated with normal or increased inctraocular pressure.
- Broadly classified into primary and secondary glaucomas.
- Primary glaucoma based on the anatomy of the anterior chamber angle, is further divided into open angle and angle closure forms.
- Secondary can be due to associated uveitis disorders of lens, trauma etc.
- Basic principle of management is surgery/laser for angle closure forms and medical treatment for open angle glaucoma.
- Counsellor should know about the main pathology in two forms of glaucomas and name of different groups of drugs that are commonly prescribed and their cost and important side effects.
- They should know about the basics of filtering surgery and counsel the patient regarding the need for surgery.
Student exercise
I. Write short answers
- Mention the symptoms of glaucoma.
- How will you counsel a glaucoma patient about the importance of medication?
- Write down the importance of follow up of glaucoma patient.
- What is the role of a counsellor in counselling a YAG PI laser patient?
- Who are all prone to get glaucoma?
