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OPINION

Understanding Glaucoma

Glaucoma is a progressive optic neuropathy which has multiple risk factors
Dr Rayees Ahmad
Srinagar | Posted : Mar 14 2018 1:18AM | Updated: Mar 13 2018 11:52PM
Understanding Glaucoma
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Glaucoma (is the second most common cause of blindness and first most common cause of irreversible blindness. The global prevalence of glaucoma for population aged 40-80 yrs is 3.54%. In 2013 the number of people (aged 40-80 yrs) with glaucoma worldwide was estimated to be 64.3 million increasing to 76 million in 2020(Glaucoma and projections of glaucoma blindness through 2040, American Academy of ophthalmology). One in every eight person above the age of forty years is either a glaucoma suspect, or already a victim. One in every 3000 new born is a case of congenital glaucoma.

Glaucoma is a progressive optic neuropathy which has multiple risk factors, the increase in IOP being the most common and modifiable one. Many other risk factors include blood supply, postural drop, diurnal variation, ethnic background, family history and older age. In central nervous system , neurons have their cell bodies in the inner retina and axons in the optic nerve. Degeneration of these nerves results in cupping, a characteristic appearance of the optic disc and visual loss.

Glaucoma broadly can be classified into congenital and adult glaucoma’s. Congenital glaucoma is mostly due to the mal-development of the angle of the anterior chamber. Adult glaucoma’s are broadly classified into open angle and closed angle glaucoma’s. 

Though the major part of glaucoma patients comprise of open angle but the severity of vision loss seems to be more disproportionate in acute angle glaucoma.

In the open angle glaucoma the drainage channels are normal or subnormal but the level of IOP increases in the eye which causes pressure and mechanical effects on the eye ball and hence the damage. In angle closure glaucoma the drainage channels are affected and are closed. The path to aqueous drainage is obstructed and hence the level of IOP  increases and damage starts.

The normal range of IOP is from 12-21mmhg. Glaucoma may go symptom less for a very long period of time and can be detected at very advanced stages.

 

Open angle Closed angle

Congenital glaucoma

Symptoms-usually none

May have loss of central

And peripheral vision later

Signs –elevated IOP

Visual field changes,

Glaucomatous disc changes symptoms-severe eye ache,

headache, pain blurred vision,

red eye , nausea vomiting, halos

lights, intense eye ache

Signs-red teary eye, corneal

oedema, closed angle, shallow

AC, mid dilated fixed pupil, iris atrophy symptoms-irritability,

photophobia, epiphora

poor vision.

signs-elevated IOP, bupthalmos,

Haab,s Striae, corneal clouding

glaucomatous cupping.

 

Various tests

Intraocular pressure measurement

Gonioscopy (A test to see outflow channels of the lens)

Optic nerve imaging

Pupillary Reflex response

Refraction

Retinal Examination

Slit Lamp Examination

Visual Acuity

Visual Field  assessment

Treatment 

Medical

-Beta Blockers

These reduce the aqueous humour production. Examples include levobunolol, timolol, betaxolol and metipranol

-alpha agonists

These reduce the production of aqueous humour and increase drainage. Examples include apraclonidine and brimonidine.

-Prostaglandins like compounds 

These increase the outflow of aqueous humour. Examples include latinoprost, bimatoprost and travoprost.

-Miotic agents

These also increase the outflow of aqueous humour. Examples include pilocarpine and carbachol.

-Epinephrine compounds

These compounds such as dipivefrine also increase the outflow of aqueous humour.

-Oral medications like carbonic anhydrase inhibitor which decrease the production of aqueous.

 

Lasers

Nd Yag laser, selective laser trabeculoplasty (SLT) and argon laser trabeculoplasty are few non surgical less invasive techniques to control intraocular pressure.

Surgery

Trabeculectomy- Surgical procedure to create an alternative fistula for drainage.

Trabeculotomy- procedure used in congenital glaucoma to rupture the schelms canal.

Goniotomy- used in congenital glaucoma to incise the trabecular meshwork.

Drainage device shunt surgeries used in complicated glaucomas.

Some adjustments which patients with advanced glaucomas need to adapt are improving other senses like hearing , touch , protection from sun and low vision aids.

As I conclude one important thing to my fellow colleagues, half of the glaucoma is yet undiagnosed, diagnosing glaucoma at an early stage will definitely delay or even halt the progression of the disease. The aim is none of the patients suffering from glaucoma should go blind.

 

Dr Rayees Ahmad is MBBS, MS (Ophthal) Fellow glaucoma and Strabismology (AIIMS DELHI), Ophthalmologist, DH Ganderbal