COMPLETE GLAUCOMA DIAGNOSTIC/MONITORING WORK-UP

This is the complete detailed check-up for Glaucoma. It is of two categories:

1. Comprehensive Glaucoma Screening – done in Undiagnosed patients of glaucoma or patients at high risk of glaucoma, or just wanting a comprehensive eye health check-up. This is done at a prescribed time schedule.
2. Secondary Glaucoma Check-up – done 6-12 monthly in patients already diagnosed with Glaucoma and are in follow-up care for it. This check-up is done to ascertain the exact status of Optic nerve as well as the field of vision. This helps us to monitor the progress of the disease and to tailor the treatment according to the particular status of the disease in your eyes.

Comprehensive Glaucoma Screening: Glaucoma screening though is a must for all individuals above 40 years but its frequency is determined by the presence of certain factors. These factors point to a population at higher risk for developing Glaucoma so they need to be watched closely for the development of Glaucoma.

Risk factors for Glaucoma:

Although anyone can develop glaucoma, some people are at higher risk than others. The following are suggested as risk factors for glaucoma:

• Race: Glaucoma is the leading cause of blindness for African-Americans.
• Age: Glaucoma is much more common among older people. You are six times more likely to get glaucoma if you are over 40 years old.
• Family History of Glaucoma: The most common type of glaucoma, primary open angle glaucoma, is hereditary. If members of your immediate family have glaucoma, you are at a much higher risk than the rest of the population. Family history of glaucoma increases the risk of glaucoma four to nine times.
• High intraocular pressure
  People with an elevated (greater than 21 mm Hg) intraocular pressure (IOP) are at an increased risk.
• Indiscriminate use of Steroids: Studies indicate Steroids increase intraocular pressure. These could be in the form of Oral medications, Steroid Inhalers and Steroid Eye Drops used for long periods of time. Patients who are on long term steroid therapy for other diseases such as asthma, arthritis etc.
• Injury to Eye:Injury to the eye may cause secondary open angle glaucoma. This type of glaucoma can occur immediately after the injury or years later.
• Diabetes: Some diseases that impact the entire body, such as diabetes, anaemia, or hardening of the arteries, increase the risk of the condition. Persons who do not actually have diabetes, but have a strong family history of the problem, should have their eyes checked frequently for early development of the disease.

Other possible risk factors:

• People having high minus or plus numbered glasses
• Hypertension
• Central corneal thickness less than 500 microns.
• People who have undergone any kind of eye surgery.
• People with thyroid gland related ailments.
• People with over – mature cataracts.

Recommended Schedule for Glaucoma Screening:

The American Academy of Ophthalmology’s recommended intervals for eye exams are:

• Age 20-29: Individuals of African descent or with a family history of glaucoma should have an eye examination every three to five years. Others should have an eye exam at least once during this period.
•  Age 30-39: Individuals of African descent or with a family history of glaucoma should have an eye examination every two to four years. Others should have an eye exam at least twice during this period.
• Age 40-64: Individuals should have an eye examination every two to four years.
• Age 65 or older: Individuals should have an eye examination every one to two years.

Investigations done at Angel Eyes Lasik Centre for Glaucoma Screening includes the following tests:

• Vision testing
• Tonometry
• Pachymetry
• Gonioscopy
• Pupil dilation and Ophthalmoscopy
• Visual Field (Perimetry)
• GDxVCC – Retinal Nerve Fibre Layer Analysis
• OCT (Optical Coherence Tomography)

In patients where these tests conclusively point to a ‘glaucoma – free’ eye, the patient is advised to undergo next screening depending upon the risk factor present and the age of the patient.  In patients where Glaucoma is detected, the patient will have to start one or the other form of treatment. In such cases the patient is advised to undergo detailed Glaucoma Check-up every 6 months to 1 year, besides the routine follow-up.

Secondary Glaucoma Check-up: This is done in cases where Glaucoma has already been diagnosed. These tests are necessary to ascertain the exact status of the optic nerve as well the field of vision. Based on these results we are able to judge the efficacy of our treatment. Any changes or adjustments in the treatment plan makes more sense if they are co-related with these results. These tests will also help to monitor the disease in a more objective way. Though essentially quite similar to Glaucoma screening, the basic difference will be in scheduling/frequency of these tests.

• Tonometry: done on every visit to the centre.
• Pachymetry: This test is will not be repeated if done earlier during screening.
• Gonioscopy: done on every visit to the centre.
• Pupil dilation and Ophthalmoscopy: done every 3 months.
• Visual Field (Perimetry): recommended every 6 months to 1 year.
• GDx VCC – Retinal Nerve Fibre Layer Analysis: recommended every 6 months to 1 year.
• Vision testing: done on every visit to the centre
• OCT (Optical Coherence Tomography): recommended once every year

Procedure for getting Complete Glaucoma Check-up done at Angel Eyes Lasik Centre:

1. To schedule a complete Glaucoma check-up of any category you have to book an appointment where you should clearly mention that you want to schedule a complete check-up for Glaucoma.
2. The total time required for the check-up may be around 2 hours so you should come with this much time in hand. Do not try to hurry up the procedure as this may lead to doubtful results.
3. As pupil dilating drops will be used, you must have someone to drive you back home after the tests.
4. Please ensure that when you come for tests your eyes are in reasonably good health. Those suffering from any infectious disease like conjunctivitis or from allergic eye disease should wait before they come for the complete Glaucoma check-up.
5. Once at our centre, after contacting the reception and registration, you will be administered the check-up in a step-wise manner as decided by the staff or consultant looking after you.
6. You will need to move to different sections for tests by different equipment as described in our protocol.
7. Almost all the reports are available immediately.
8. Once the reports are available you will be seen by the consultant who will review the reports and inform you about the results.
9. According to your results you will be either started on a treatment regime and advised about follow-up glaucoma check-up schedules (if diagnosed as having glaucoma).
10. If the results are normal and you do not seem to have glaucoma, then you will be advised to have next screening according the schedule for different age group and as per the presence of risk factors.

Though the status of your vision (ascertained by refraction) and the status of IOP (ascertained by applanation tonometry), will give us a fair idea of the efficacy of treatment, the best way to judge the efficacy is to quantify the status of the optic nerve and the status of your field of vision. The optic nerve fibre analysis is accomplished by doing GDx VCC examination. The status of field of vision is determined by Humphrey Field Analyser. These two tests are not included in the routine follow-up. Moreover, a six to twelve monthly examination of these two parameters is more than sufficient and is not recommended on every routine follow-up visit.

Detection of Glaucoma:

Unfortunately, glaucoma is a disease, which cannot be seen or felt by the patients in the early stages.  It is usually spotted during the course of a routine eye check-up done by an Eye Surgeon, when he detects presence of risk factors as discussed above or when high IOP is suspected and more detailed test is conducted. A surgeon may also suspect Glaucoma when he finds on examination increased cup:disc ratio with or without raised IOP.  The mistake that most people commonly make is getting only their glass numbers checked by an Optician ignoring the need for a detailed eye check-up.

Sometimes the patient discovers it and come to the Doctor with complaints of mild headache, fuzzy vision in morning or seeing rainbow colours around lights. These all should lead to suspicion of raised IOP and warrant further detailed testing for Glaucoma.

In addition to a complete medical history and eye examination, your eye care professional may perform the following tests to diagnose glaucoma.

Description and Procedure for Various Diagnostic Tests for Glaucoma:

Tonometry: This determines the IOP in the eyes. This is done in two ways:

Non-Contact Tonometry – This is done by an equipment known as Non- contact tonometer. As the name suggests, the surface of the eye is not touched during examination. As the patient focuses on a given target, a puff of air is directed at the surface of the eye. This is then measured to find out the IOP. More for screening

Applanation Tonometry – This is a extremely accurate method of determining IOP. However, in this procedure a dye is instilled in the eye along with anaesthetic drop to anaesthetize the surface of the eye. The probe in this method touches the surface of the eye to record the IOP, so its sterility is a must. The process takes slightly more time than the non-contact method and can be performed only by the consultant.  At Angel Eyes, applanation tonometry is routinely done for all glaucoma patients on every visit.

Pachymetry: This investigation measures the thickness of the cornea. Drops are used to anaesthetize the surface of the eyes. The pachymeter probe is then brought in contact with the surface of the cornea to measure the thickness in various quadrants of the cornea. This test is done only once as the thickness of the cornea is not expected to change over time.

Gonioscopy: This is a diagnostic examination procedure done to assess the condition of the angles of the eye. This is done in known or suspected cases of Glaucoma. It is usually done at 6 -8 monthly interval. This is done under topical anaesthesia i.e. numbing drops are instilled in the eye before testing.  After numbing the eye, special type of lenses known as Gonio lenses are positioned on the eye and the angles are examined with the help of slit-lamp. Its importance lies in planning the treatment of glaucoma irrespective of it being medical/surgical/laser treatment.

 Pupil dilation and Ophthalmoscopy: Dilating drops are instilled in the eye to dilate the pupil so that we can see the optic nerve and the retina. The dilating drops will keep the pupil dilated for around 4-5 hours and the vision will remain blurry for this duration. You must not drive or try to do fine work during this period.

Visual Field (Perimetry): We use Zeiss Humphrey Field Analyzer for this purpose. For those already diagnosed with Glaucoma, Perimetry is recommended every 6 to 12 months. To get perimetry done you will be required to book an appointment specifying that you need this test done as the time required for this test is approximately 1 hour and there may be patients already booked for this procedure. This test does not involve any drops to be instilled and is a no-touch test.

Retinal Nerve Fibre Analysis: We use Zeiss GDx VCC for doing this investigation. This is an essential test to pick up early cases of neuronal damage. It is a quick and comfortable test where a laser is used to obtain clear scanned images of the Retinal and Optic nerves, so we can see in amazing detail the structures involved in order to monitor Glaucoma like never before! This allows us to measure the size of your nerve, and ensure that any abnormal change is detected quickly, before any damage appears in your vision. 
This is a very accurate method of determining the status as well as the amount of damage done by glaucoma to the eye. This test should be repeated every 12 months in known patients of glaucoma. Based on the results of this test and the perimetry, we can plan the treatment of glaucoma in a particular patient so as to preserve the optic nerve and vision as much as possible.

To get this test done you will be required to book an appointment specifying that you need this test as the time required for this test is approximately half an hour and there may be patients already booked for this procedure. This test does not involve any drops to be instilled and is a no-touch test.

OCT (Optical Coherence Tomography):

Optical coherence tomography (OCT) is a non-invasive imaging test. OCT uses light waves to take cross-section pictures of your retina.

With OCT, your ophthalmologist can see each of the retina’s distinctive layers.  This allows your ophthalmologist to map and measure their thickness. These measurements help with diagnosis. They also provide treatment guidance for glaucoma and diseases of the retina. These retinal diseases include age-related macular degeneration (AMD) and diabetic eye disease.

 Today, optical coherence tomography has become a standard tool for diagnosing and monitoring glaucoma. As with many advanced technologies, there are several ways we can use OCT to help in diagnosis and management of Glaucoma cases.

OCT is most useful when a patient is either a glaucoma suspect or has early-to-moderate disease, as a tool for helping to detect damage and progression (or conversion from glaucoma suspect or ocular hypertensive to glaucoma). While there are many parallels between OCT technology and visual fields—for example, being able to use them for either event-based analysis or trend-based progression analysis—OCT is arguably a better tool for use in early disease, because when we test visual function with a visual field test, the plasticity and overlap inherent in the visual system tend to compensate for any early damage. As a result, early damage may be picked up by an OCT scan rather than by a visual field test. OCT gives us a wealth of data to work with, because it can provide structural information about many parts of the retina and optic nerve head.

To prepare you for an OCT exam, your ophthalmologist may put dilating eye drops in your eyes. These drops widen your pupil and make it easier to examine the retina.

You will sit in front of the OCT machine and rest your head on a support to keep it motionless. The equipment will then scan your eye without touching it. Scanning takes about 5 – 10 minutes. If your eyes were dilated, they may be sensitive to light for several hours after the exam.

The OCT test which is commonly performed for glaucoma and macular degeneration, can usually be done without pupil dilation, but it is commonly performed during the annual dilated exam.  A baseline test takes approximately 10 minutes. Repeat scans take approximately 5 minutes per eye.

Eye conditions OCT helps to diagnose

OCT is useful in diagnosing many eye conditions, including:

• macular hole
• macular pucker
• macular oedema
• age-related macular degeneration
• glaucoma
• central serous retinopathy
• diabetic retinopathy
• vitreous traction

OCT is often used to evaluate disorders of the optic nerve as well. The OCT exam helps your ophthalmologist see changes to the fibres of the optic nerve. For example, it can detect changes caused by glaucoma.

OCT relies on light waves. It cannot be used with conditions that interfere with light passing through the eye. These conditions include dense cataracts or significant bleeding in the vitreous.