- This is eye condition in which some parts of eye involve, damage in optic nerve- it means the nerve who carries a visual sensation to brain, in most of the cases because of high intraocular pressure-IOP (high eye pressure).
- So that eye pressure is the common factor in glaucoma or in the case, optic nerve is damage but no IOP raise called normal tensive or Low tensive glaucoma.
- And in some of the conditions IOP is higher but no optic nerve damage called Ocular hypertension.
- Normal range of IOP is 12 to 20 mm of Hg.
What is IOP?
- It is intraocular pressure means the eye pressure which requires to withstand the eyeball or eye to maintain their shape and structure.
- For maintaining the eye pressure eye have some liquid and gelatinous material or humour known as aqueous humour.
- The production and drainage of aqueous humour get main role of maintaining a IOP.
Why should IOP raise?
- If production of aqueous humour is normal but drainage is blocked, so amount of aqueous is higher in eye, that increases pressure on other eye structure cause high IOP.
- In some of the cases production is higher and drainage is normal even though the IOP raise.
Types of glaucoma:
1. Open angle glaucoma
- It means drainage angle is open even though IOP raise and damage optic nerve.
- Slowly raised IOP (>21mm of Hg)
- No symptoms except slow vision loss
- No known cause.
- Family history of glaucoma.
- Risk increase after age of 40 year.
- More common in myopic (minus number) patient.
- Diabetic have a high risk.
- Cigarette smoking.
- High blood pressure patient.
- Check the IOP with GAT (gold standard application tonometer).
- Retina examination in dilating eye.
- Perimetry to check visual field defect ( vision loss).
- Pachymetry to check central corneal thickness (CCT) to estimation of IOP.
2. Angle closure glaucoma
- Obstruction of aqueous outflow because of narrow drainage angle.
- Sudden IOP raise ( between 40 to 70 mm of Hg).
- Sudden pain, nausea and vomiting.
- Headache, watering, redness.
- Rapid vision impairment.
- No known cause.
- Usually after age of 60 years.
- More common in female.
- Common in hypermetropic (plus power) patient.
- Structurally small eye./li>
- Similar as open angle.
- Gonioscopy to check Anterior chamber Angle (drainage angle).
3. Secondary glaucoma
Secondary glaucoma has a group of conditions in which raise IOP associate with primary eye disease or systemic disease.Primary eye conditions are:
- Lens induce
- Inflammatory diseases
- Steroid related
- Traumatic or after some eye injury
- Glaucoma with some eye tumours.
After all the investigation if your eye practitioner may diagnosed glaucoma, than you have been on prescription of anti glaucoma drugs. 3 types of anti-glaucoma drugs.
- To increase aqueous drainage
- To decrease aqueous production
- OR the combination of both
- Peripheral iridectomy: in angle closure glaucoma.
- Argon laser(ALT) or diode laser (DLT): for additionally increase aqueous outflow in angle closure glaucoma.
- Selective laser trabeculoplasty (SLT): for open angle glaucoma.
In some of the cases even after medication and supportive laser treatment patients IOP may poorly control than only the glaucoma surgery prescribed.
Surgical procedures for glaucoma
- Peripheral iridectomy
- Treatment of angle closure glaucoma.
- Now a-days laser iridotomy should be preferred over surgical iridectomy.
Filtration operation (trabeculectomy)
- this operation provide a new channel for aqueous outflow and successfully control the IOP.