GLAUCOMA

GLAUCOMA

Glaucoma : is a group of eye diseases in which the optic eye nerves is damaged leading to irreversible loss of vision, in the most cases this damage is due to increase pressure within the eye.

GLAUCOMAcaused by:

-increased intraocular pressure / ocular hypertension (high pressure of fluids "aqueous humor" within the eye),

complication: -possible optic nerve damage.

liquid aqueous humor:produced by ciliary bodies, flows into posterior chamber, flows through pupil, flows into anterior chamber, drained by trabecular meshwork.

 

In a healthy eye the rate of secretion is balanced with the rate of drainage.In glaucoma, the drainage canal is partially or completely blocked, fluids build up in the eye chamber leading to increased pressure.

GLAUCOMAThere are two type of glaucoma open angel and closed angle glaucoma.

Open angle glaucoma (chronic glaucoma) is caused by partial blockage of the drainage canal.

Closed angle glaucoma ( acute glaucoma )is caused by sudden or complete blockage of aqueous humor drainage the pressure within the eye.

GLAUCOMAopen /wide-angle glaucoma

1 )degeneration & obstruction of trabecular meshwork.2)reducing drainage of aqueous humor

3)increased resistance & chronic buildup of pressure in the eye.

 close/narrow-angle glaucoma

1)complete closure of iridocorneal angle.2)reducing flow of aqueous humor from posterior

chamber to anterior chamber.3)increased resistance & acute pressure in the eye.

Treatment of glaucoma -The aim is to lower intra-ocular pressure

-Topically (B-blockers, parasympathomimetics)OR systemic (carbonic anhydrase inhibitors, osmotic diuretics)

-First line therapy: B-blocker, prostaglandin analoges, alpha 2 agonist and carbonic anhydrase inhibitor .

Treatment of open angle glaucomaB-blockers:

First choice of treatment. MOA: block beta receptors in the

ciliary epithelium and reduce the secretion of aqueous humour.

Side effects: bradycardia, headache, dyspnea.

Treatment of open angle glaucomaprostaglandin analoges:

Are used topically to lower intra-ocular pressure.

Examples: travoprost , bimatoprost , latanoprost .

alpha 2 agonist:Example : brimonidine .

Treatment of open angle glaucoma Carbonic anhydrase

inhibitors :

Used with the previous medications.

MOA: reduce production of aqueous humour.

Side effects: confusion, drowsiness, nausea.

Treatment of open angle glaucomaparasympathomimetics:

MOA: facilitate ocular drainage by constricting the pupil and pulling open the meshwork.

Side effects: blurred vision, brow ache, itching.

Pilocarpine eye dropcarbachol

Treatment of open angle glaucomaEye drops contain

tow medications.

Treatment of closed angle glaucomaShould be started within 24 -48 hours .

If it is delayed : - adhesion may form between the iris and the

cornea. - the ocular meshwork may be damaged. - leads to chronic closed angle glaucoma

then loss vision (absolute glaucoma).

Treatment of closed angle glaucoma parasympathomimetics : e.g. pilocarpine.

carbonic anhydrase inhibitors : e.g. acetazolamide.

osmotic diuretics : e.g. mannitol and urea (IV), glycerol or isosorbide (orally).

prostaglandin : which is used topically to lower intra-ocular pressure.

Treatment of closed angle glaucomaOsmotic diuretic :

Used in the short-term management of glaucoma prior to surgery.

MOA: reduce vitreous volume and cause

marked reduction in intra-ocular pressure.

Side effects: oral dryness, ocular dryness, headache, dizziness.

- Usually we start with the non-surgical treatment if it was not effective, we go to laser therapy and lastly we go to surgical treatment. - But in emergency cases (closed-angle glaucoma) the surgery is the first choice.

Surgical treatment of glaucoma

Surgical treatment of glaucoma

Patient who have had a previous ocular surgery there is a high failure rate, due to formation of scar tissue.

We can give injection of anti-proliferative agent such as fluorouracil, that has been shown to reduce the failure rate of surgery. (S/E: increased epithelial toxicity and conjunctival wound leaks).

After the surgery we give antibacterial and anti-inflammatory drugs, on the afternoon of the same day of the surgery , we measure the ocular pressure and if we observe that the pressure started to rise (20 mmHg instead of 15 mmHg), we give anti-glaucoma drug, but we have to be careful not to mix them with the post-operative drugs, we give them in different times. OR we give Diamox® tablets after the surgery as an anti-glaucoma agent.

Surgical treatment of glaucoma

Anti-bacterial agents:Dexacol®: eye drops

(Chloramphenicol,Dexamethasone)Steroidal antibacterial drug.

Zymar®: ophthalmic solution(Gatifloxacin-fluoroquinolone): Antibacterial that is active against pathogens that are resistant to other antibiotics.

Post-operative agents

Anti-inflammatory agents:Nevanac® (Nepafenac 0.1%):

non-steroidal anti-inflammatory drug (NSAID).

Pred Forte® (Prednisolone acetate): steroidal anti-inflammatory drug.

Surgical treatment of glaucoma

Martindale, The extra pharmacopoeiua, the thirty-first edition.

Referances

By:Laila FalanaHadeel Abu MhameedReem Aqtash