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Good Hope Hospital Eye Clinic

Pre-perimetric glaucoma   David Kinshuck



Introduction

Glaucoma is described here. Pre-perimetric glaucoma is essentially early chronic open-angle glaucoma. It may be called

  • early glaucoma
  • glaucoma suspect
  • borderline glaucoma
 

 


Glaucoma

In glaucoma the optic nerve becomes damaged, and after sometime the sight becomes reduced.

The optic nerve is the 'electric wire' of the eye, an it takes messages about what you see on towards the brain. In the main type of glaucoma the optic nerve is pressed on by extra fluid in the eye, and this may damage the sight in the eye.

the optic nerve is the electric wire of the eye taking messages to the brain

 


Pre-perimetric glaucoma

If you have pre-perimetric glaucoma, your ophthalmologist believes that you are developing glaucoma or have early glaucoma. But by definition your visual fields will be full, and your sight very good.

But if the condition was untreated, the optic nerve would become more damaged and, the visual fields would shrink, and then the sight reduced. So generally treatment will be needed to stop further damage to the optic nerve.

It is diagnosed using the latest tests etc

  • the HRT or OCT test may suggest glaucoma
  • the optic disc is seen to be 'cupped'
  • the visual fields are full (if there is a visual field defect or section of your sight missing, the diagnosis will usually be true 'glaucoma').

The treatment is generally drops to lower the eye pressure, such as

  • Xalatan
  • Travatan
  • Lumigan
  • Saflutan (preservative free ampoules)
  • or other drops
  • sometimes a combination of drops is needed

Check ups will be needed about 3 months of starting the drops to check the pressure is low enough, and every year after that. At the check ups,

  • pressure is measured
  • visual fields are tested yearly
  • the optic disc is examined
  • the drainage angle is measured (sometimes with a contact lens)
  • an HRT or OCT scan may be performed, perhaps every 2 years

Your ophthalmologist tries to achieve a low eye pressure

  • if the optic nerves looks damaged, a pressure of 12-14 or below
  • if the optic nerve is healthy, a slightly higher pressure (but then do you have this condition?)
  • once the low pressure has been achieved, the condition is usually stable.

The main cause of the condition is the blocked drain, see. But sometimes the condition is poor blood flow to the optic nerve etc see.

 

 

These are some notes from the glaucoma page that may be relevant:


Genes and your relations
Glaucoma is much commoner as we get older but tends to run in families.

Genes control the blockage of the drain (the 'trabecular meshwork'). The relations of patients with glaucoma should all be checked for the condition. If you have glaucoma and you are 70y, then all the relations (mainly children and sisters and brothers) should be checked from the age of 50y. If you have glaucoma age 30y, then even the children related to you should be checked (again: sons/daughters/brothers/sisters). See.

 

 


The sight in glaucoma

At first the sight is normal, but it if the glaucoma is severe, the sight may get  progressively worse as opposite.
You cannot 'feel' glaucoma, and usually would would not know there was anything wrong in the early stages.

See Case 1 for students

visual fields become progressively worse if the eye pressure is not low enough
At first the sight is normal,

 

 

then a small area of poor vision may develop.

 


This can extend, affecting much of of the sight,

 

or nearly all the sight.

 

A common type of loss of vision in glaucoma.

 


How does the doctor or optometrist know you have glaucoma?
Glaucoma is found by an ophthalmologist or optometrist by
  1. measuring the eye pressure (for this & other details about your examination
  2. looking into the eye at the optic nerve (the nerve can appear 'caved in' which we call 'cupped', as though it has been pressed on.
    See photo, and Case 1 for students
  3. testing the field of vision: you sit in a special machine with your head still. Lights flash, and you are asked to press the button if you see the light. If you cannot see the brighter lights, this shows on the computer print out rather like the drawing of the 'castle' above. Here is an online website that enables you to test you own visual field.
 

 


Treatment for chronic glaucoma in adults

Chronic glaucoma is treated with

Drops
  • The basic treatment for glaucoma is eye drops, and the main drop is Xalatan (or lumigan or travaprost). This is a very effective drop, although does not work in all patients. It causes an allergy in about 1%.
  • The second commonest group of drops inhibit the carbonic anhydrase enzyme. This is the chemical that produces the aqueous fluid in the ciliary body. The main drop now is azopt.
  • The third is one of the beta-blocker drops such as betaxalol or timolol or teoptic. These drops switch the tap off that makes the fluid. You generally should not use these drops if you get asthma or breathing difficulties, and should use an alternative drop. They may slow the heart down (if they make you dizzy you should stop them) or make your ankles swell.

Drops are described in more detail.

In practice the maximum combination of drops that can be used with few side effects are these 3 drops combined, such as xalatan at night, timolol LA morning, and azopt 2-3 times a day.
There should be a 10 minute gap between drops so one does not wash the other out. This combination does tend to cause slightly sore eyes, which is unfortunately unavoidable (systemic medications cause sore eyes also).

Laser

Laser may help a little in older patients, see. Argon laser trabeculoplasty is the main operation available, but selective laser trabeculoplasty may be more effective.

Surgery

With new drops such as Xalatan this is needed less often. However, it is occasionally necessary, especially for younger patients. See some notes here. See animation.

Here are Good Hope mitomycin results. Some wonderful videos and other information here.

Some patients, especially older patients or those who have had previous trabeculectomy, may need cyclodiode laser.

 


Will the sight get worse?
Once the pressure reaches a satisfactory level the glaucoma should not

A satisfactory pressure if the optic nerve is healthy is 18-20mmHg, if the nerve is slightly damaged 14-16, and if considerably damaged 10-12 would be ideal.
(The pressure level needed also depends on your type of glaucoma. People with 'low tension glaucoma' need a lower pressure, for instance.) People who have a pressure of 14 that never rises above 14 usually notice little progression.

Effectively research has shown that if a pressure is 10mmHg, hardly any eye will be further damaged from pressure, if 11mmHg, then 10% of eyes/patients will notice a deterioration, and so on up to 20mmHg.

It is very hard for an ophthalmologist to tell which eyes will get worse, but

  • eyes with healthy looking optic nerves can take a higher pressure
  • anaemia, migraine, cold hands, sleep apnoea, suggest a lower pressure is helpful
  • if the visual field is full, a higher pressure may be well tolerated
  • younger patients with very cupped discs and visual field missing do need very low pressures, ideally 10mmHg
  • people with optic disc haemorrhages are at much higher risk

At 20mmHg most eyes will deteriorate. But in practice the risks of treatment, such as having to use lots of drops, and particularly that of diamox tablets or surgery, have to be balanced against the ideal of seeking a pressure of 10 for all patients. In practice accepting a higher pressure in a particular patient may still mean very few patients notice much deterioration, and is the best option. Indeed, in an elderly patient using 2 or 3 drops there may be no safe alternative, especially if this includes xalatan (or lumigan or travaprost).

 

 


Tests each visit

At each visit these results will be analysed

  • eye pressure...measured most visits
  • optic nerve appearance and cupping....measured most visits
  • visual fields..tested about yearly (see this excellent IGA article which shows you how to interpret your visual field test...it also discusses how often the test should be carried out)
 

 


Your general health in glaucoma/intraocular hypertension

Remember that your general health and lifestyle have a major impact on glaucoma and your sight. BJO 12

  • Smoking does increase the eye pressure, and will make your glaucoma worse. It also increases the risk of retinal vein occlusion (which occur in glaucoma), macular degeneration, cataracts, stroke, and heart attacks. The exact risk is not known, but in some patients 20 ciagettes / day will increase loss of vision by 400%. Passive smoking 20 a day is equivalent to smoking 5 cigarettes a  day, and increase visual loss 100%.

  • metabolic sydrome is strongly related intraocular pressure (Nature 2010). This is related to (as below) lack of exercise, high blood pressure, obesity and liver and kidney problems. Treatment of the metabolic syndrome will help lower eye pressure 0.8mmHg..

  • Exercise lowers the eye pressure, 'an hour a day (walking) will keep the doctor away', and half an hour will help a lot. See. Any exercise will do... eg walking, swimming, gardening.

  • high blood pressure will be harmful as this may, together with the glaucoma, cause a retinal vein occlusion. A blood pressure of 140 systolic or less, may be best, and may be lower the better as long as you feel well. See   But there are other views. We now know that eye pressure and blood pressure are related; the implication of this is that lowering blood pressure will help in the treatment of glaucoma. So keeping your blood pressure reaonably low is an important part of the treatment, although too much medication may cause problems.

  • Obesity results in high blood pressure, lack of exercise, and indirectly will cause problems. Many obese patients suffer from sleep apnoea....

  • Oily fish will help the circulation and probably help prevent retinal vien occlusions. Red meat  (including pork/ham) increase blood pressure; they are best replaced, at least in part, by fish, and pulses such as lentils and beans. Nuts have some healthy fats, and may be helpful in small amounts...but they are 'fattening' and help to put weight on.  A Mediterranean diet helps.

  • 9 portions of vegetables or fruit a day will also help to keep your retinal veins and macula healthy, and prevent cataract formation...9 a day (men) 7 (women) keeps the doctor away...

  • A high saturated fat diet is very harmful as it will contribute to many conditions. A balanced diet is recommended. Saturated fat comes from full-fat diary products such as milk, cheese, many cakes and biscuits, and red meat. Statins help (surely a benefit of a low choloesterol).

  • Salt will increase blood pressure.

  • binge drinking, e.g. 4 pints of beer in one day, or more that 3 glasses of wine/day, will cause a rise in blood pressure, again contributing to all these conditions. Coffee increases PXF glaucoma.

  • Sleep problems. New research links sleep apneoa with glaucoma. Sleep problems are very common in obesity...these are likely if you snore a lot. Logically if you are overweight, it is important to lose weight to help your glaucoma. So if you do snore a lot, do lose weight, and ask your doctor if you need to be tested for sleep apnoea. 2012

  • Steroid medication puts eye pressure up. Even inhaled nasal steroids can increase the pressure 2.5mmHg. If you use nasal steroids (eg for allregic rhinitis), ask your doctor if you can reduce or stop them. Steroid tablets certainly may put eye pressure up; ask your doctor if you can reduce the dose (Do not reduce steroid tablets without seeking advice.).

  • Retinal vein occlusions: patients with glaucoma are much more prone to retinal vein occlusion. The risk of a vein occlusion is reduced by control of the glaucoma, blood pressure, and all the other general health risk factors immediately above.

 

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