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Table of Contents:-

GLAUCOMA EYES|CAUSES,TYPES,TREATMENT

 Definition of glaucoma :-

Glaucoma is a multifactorial optic neuropathy in which there is a characteristic loss of retinal ganglion cells and atrophy of the optic nerve in glaucoma eyes.

Types of glaucoma –
1.Congenital or developmental glaucoma
2. Acquired glaucoma

–  Primary angle-closure glaucoma(PACG)

-Primary open angle glaucoma(POAG)



 

CONGENITAL OR INFANTILE GLAUCOMA(BUPHTHALMOS)
Definition of Congenital glaucoma-

In glaucoma eyes it is a congenital or infantile glaucoma due to aqueous outflow obstruction ,as a result of failure of the development of tissues at the angle of anterior chamber.

SYMPTOMS OF CONGENITAL GLAUCOMA-
SIGNS OF CONGENITAL GLAUCOMA-

 

MANAGEMENT OF CONGENITAL GLAUCOMA-

Medical treatmentBeta Blockers is given only for temporary period prior to surgery.

Surgical treatment-

Rehabilitation It is important to detect and treat any refrective error and amblyopia. Corneal opacity may be treated by penetrating keratoplasty.



 ACQUIRED GLAUCOMA
1.ANGLE-CLOSURE GLAUCOMA/ACUTE ANGLE CLOSURE GLAUCOMA

Primary angle closure glaucoma is an acute ,subacute or chronic glaucoma in glaucoma eyes due to obstruction of the aqueous out flow solely caused by closure of angle by the peripheral Iris.

Etiology

Age  4th to 5th decade
Sex–  female:male=4:1
Personality emotional nervous peoples with unstable vasomotor system.

Types of the eye affected by glaucoma

Small hypermetropic eye
Shallow anterior chamber
Narrow anterior chamber due to:
– smaller cornea
– bigger size of lens
– bigger size of the ciliary body
Literality- initially unilateral but frequently becomes bilateral

Mechanism of angle closure-

1.Pupillary block mechanism- the initiating event is thought to be a functional pupillary block in mid dilated position.

GLAUCOMA EYES
                 Fig.1:- Steps in pupillary block mechanism
                                                                   

2.Plateau Iris mechanism- it is due to an abnormal Anatomical configuration of the anterior chamber angle. The angle is closed by infolding of the Iris into the angle in associated with pupillary dilation but without a significant pupillary block components. Peripheral iridectomy does not help to control IOP in this situation. Pilocarpine is the only drug which controls this situation. Otherwise surgery is required.

Stages:

It is divided into 5 stages
1. Prodromal stage
2. Stage of constant in stability
3. Acute congestive attack
4. Chronic congestive stage
5. Stage of absolute glaucoma

1. Prodromal stage
Symptoms-

Coloured halos seen around the light in glaucoma eyes
Blurring of vision by glaucoma eyes
Occasional headache produced by glaucoma eyes

Signs-

Eye remains white and without congestion even though there may be a transient sudden rise in IOP up to the 40 or 60 mm Hg.

2.Stage of constant instability

The IOP rise in the late afternoon and evening but reduces spontaneously during sleep( as the people become constricted)

3. Acute congestive attack

An acute congestive attack occurs sooner or later and is always associated with closure of the angle and receiver elevation of IOP.

Clinical features of an acute attack-
SYMPTOMS-

Intense unbearable pain radiating along the distribution of 5th cranial nerve.
Fever headache often with nausea vomiting, often mistaken for an acute abdomen.

Sign-

Eyeball- tenderness present

Eyelids- marked edema with narrowing of the palpebral aperture

Conjunctiva- both cillary and conjunctival congestion with chemosis.

Cornea- steamy and insensitive

Anterior chamber- very shallow’ cells and flares may be present

Iris- pattern is lost and discoloured

Pupil- mild dilated and vertically oval

IOP- markedly elevated

Visual acuity- it may be reduced to perception of light and projection of rays.

Fundus- it cannot be visualised due to heavy cornea. The funds may be visible by hyperaemic optic disc with small hemorrhage and with spontaneous pulsation of the central retinal artery .

4.Chronic congestive stage-

This is sometimes called creeping angle closure or chronic angle closure glaucoma as the angle becomes slowly and progressively closed.

Clinical features-

-Visual acuity is always impaired in glaucoma eyes.
– Congested and irritable eye
– IOP remains permanently elevated
– Cupping of the disc appears
– Peripheral anterior synechiae develop.
-Typical glaucomatous field defect become evident.

5.Stage of absolute glaucoma-

– Painful blind eye with no PL
– Cornea:- cloudy and insensitive

– Anterior chamber:- very shallow.

– Iris:- patches of atrophy, ectropion of the uveal pigments.

– Pupil:- dilated and grayish in appearance

– Tension:- extremely high

Diagnosis-

-Coloured halos
– Gonioscopy
– Provocative tests

Colored halos-

The coloured halos are due to accumulation of fluid in the corneal sexyepithelium and alterations in the refractive condition of the corneal lamellae. Similar colored halos may seen in the early cataract. These two can be differentiated by Fincham’s stenopeic slit test.

Click here to Read more:-  Physiology
Gonioscopy-

The purpose of gonioscopy is to identify abnormal angle structures, and to estimate the width of the chamber angle in glaucoma eyes.The gonioscopy is based on the total internal reflection.

Types of gonioscopy-

Direct gonioscopy with gonio lenses- They provide a direct view of the angle. They are used both as Diagnostic and operative purpose.

Indirect gonioscopy with gonioprisms- They provide a mirror image of the opposite angle, and can only be used under a slit lamp.

Provocative tests –

Darkroom test – the patient is left in a dark room for 1 hour . He must remain awake so that people remain dilated.

Prone test – the patient lie in prone position for 1 hour.

Prone- darkroom test –  the patient lies prone in dark room for 1 hour. This appears to be the most popular and best physiological provocative test.
After 1 hour, the IOP is measured, and gonioscopy is performed. A pressure rise of 8 mm HG or more in presence of a closed angle is taken as a positive response.
If the Provocative test is negative – this does not necessarily mean that the angle is incapable of closer in near future. The patient should be warned of possible symptoms of angle – closer and followed up periodically.
A positive provocative test – means that the angle is capable of spontaneous closure, but it does not mean that closer is imminent or inevitable. So the possible complications of iridectomy or laser iridotomy have to be weighed against the risk of Frank ACG.

Management –
Medical therapy:

Tablet acetazolamide (250 mg) 2 tablets and then followed by 1 tablet 4 times daily with potassium supplement.
Corneal indentation – simple repeated indentation of the central part of the cornea with asquint hook ora sterile swab-stick may be effective in opening the angle. Buy this maneuver aqueous will exist from the anterior chamber and the IOP will drop.

Hyperosmotic agents –

Intravascular injection of mannitol (20%) – the dose is 1-2g/Kg body weight,i.e. 300-500 ml is given intravenously over a period of 30-45 minutes.

Oral glycerol (50% solution) – 30 ml of pure glycerol with equal amount of fruit juice(lemon), 3 times daily. Cannot be used in diabetics.

Isosorbide – it is used orally and it does not cause nausea. It can be used safely in Diabetic patients.

Pilocarpine (2% or 4%) eye drop is instilled every 5 minutes till the people get constricted, then 3- 4 times daily.
Strong analgesics(even injection pethidine) and antiemetic may be needed to reduce pain and vomiting.
Steroid antibiotic drops are instilled frequently to reduce congestion.

Surgery-

1. Laser iridotomy or surgical peripheral iridectomy
2. Filtration surgery

Laser iridotomy:- in general Nd:YAG or argan laser iridotomy has replaced surgical peripheral iridectomy in most cases.

Advantages

– a non-invasive procedure without any chance or infection.
– a painless, OPD procedure.
– it is cheap for the patients.

Disadvantages

– not widely available as the instrument is costly.
– difficulty to perform in presence of corneal edema and Flat anterior chamber.
– may cause corneal endothelial burns and localised lental opacity.



2.OPEN ANGLE GLAUCOMA

Primary open angle glaucoma is a slowly progressive bilateral raised IOP within open angle and associated with glaucomatous cupping and visual field loss it was previously referred to as a chronic simple glaucoma.

Etiology

Age- common in fifth and sixth decade.

Sex- equal in both sexes.

Inheritance- probably in a multifactorial manner . In 5-20% cases POAG runs in family.

Ocular association- examples are high myopia retinal venous occlusion retinal detachment retinitis pigmentosa.

Systemic association- examples are diabetes mellitus, thyroid disorders, cardiovascular abnormalities.

Corticosteroid responsiveness- individual with primary open angle glaucoma are a family history of the disease are more likely to respond to chronic steroid therapy with a significant rise in IOP.

Symptoms

– Painless, progressive loss of vision.
– mild headache or eye ache.
– increasing difficulty in near works and frequent change of presbyopic glasses.
– a defect in the visual field.

Signs

-Visual acuity may remain good till the later stage.
– cornea is usually clear.
– Anterior chamber depth is normal.
– pupillary reaction remains normal until the late stage.
– increased IOP with a large diurnal variation.
– cupping of the optic disc.

The diagnosis of primary open angle glaucoma therefore depends on classical trade off:

– raised IOP
– cupping of the optic disc
– classical visual field defects

Raised intraocular pressure

– morning rise of tension- 20% of cases
– afternoon rise of tension- 25% of cases
– biphasic rise of tension- 55% cases
The variation of intraocular pressure over 5 mm Hg should always excite suspicion of glucoma even although the whole reading lies under the limit of 21 mm Hg.

Cupping of the optic disc

Primary open angle glaucoma is usually suspected by finding and abnormal optic disc on routine fundus examination. Documentation of progression or arrest of cupping ,together with perimetry, plays a vital role in assessing the efficacy of treatment.

Classical visual field defects

The normal visual field is described by Traquair as island of vision surrounded by sea of blindness.
There are several techniques of testing the field of vision:-
-Confrontation technique
-Kinetic technique
-Tangent Screen
-Static technique

Click here to Read more:-  Anatomy
Investigation-

-Diurnal Variation:- IOP

-Gonioscopy:- By defination ,the anterior chamber angle is open,and grossly normal in eyes with POAG.

-Tonography:- The POC ratio is thought to be more sensitive parameter in this situation.

-Water drinking provocative test:- The patient is instructed to drink 1 liter of water, following which applanation tonometry is performed every 15 minutes for 1 hr.
A rise of 8mm Hg is said to be significant.
Performing tomography after water drinking test has an additional diagnostic value.The mechanisms of IOP rise is due to increased aquoeus secretion due to reduced serum osmolality.

-Slit lamp examination:- of the anterior segment is to rule out other cause of open – angle glaucoma.

-Perimetry and scotometry.

Treatment of Glaucoma

The aim of the treatment is to prevent the field loss which results from too high an IOP.

Modes of treatment:-

-Medical therapy
-Laser therapy
-Surgical therapy
-Combination therapy

Medical therapy
1.Beta Blockers

-MOA= Decreased aqueous secretion
-Percentage IOP lowering effects= 20-25%
-Examples= Timolol,Betaxolol

2.Prostaglandin analogs

-MOA= Increased aqueous outflow (Uveoscleral)
-Percentage IOP lowering effects= 25- 30%
-Examples= Letanoprost, Travoprost

3.Alpha adrenergic agonist

-MOA= Decreased secretion and increased uveosleral outflow
-Percentage IOP lowering effects= 15- 20%
-Examples= Brimonidine

4. Carbonic anhydrase inhibitor

-MOA= Decreased aqueous secretion
-Percentage IOP lowering effects= 15- 20%
-Examples= Dorzolamide, Brinzolamide

5.Miotics

-MOA= Increased aqueous outflow (trabecular)
-Percentage IOP lowering effects= 15- 20%
-Examples= Pilocarpine

Laser Therapy:-

Argon laser trabeculoplasty (ALT) is indicated when POAG is not well controlled with medical therapy.
It is safe, noninvasive OPD procedure.The average drop in IOP is 8 – 10 mm Hg.

Surgical Therapy:-

Indications for surgical therapy are:-
1. POAG cannot be controlled with maximal medical therapy.
2. The patient cannot tolerate medical treatment,due to toxicity.
3. The compliance of the patient is poor , or when the follow- up is unreliable.
4. Some Surgeons prefer early surgical intervention.

Types of surgery for glaucoma eyes

Given below are some surgeries possible in glaucoma eyes:-

1. Free- filtering= Full thickness fistula surgery.eg:-Scheie’s thermosclerostomy

2. Gaurded- filtering= Partial thickness fistula surgery. eg:- trabeculectomy

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