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 world wide 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 patient. One in every 3000 new borns 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 , diurinal 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 adultglaucomas. Congenital glaucoma is mostly due to the maldevelopment of the angleof the anterior chamber. Adult glaucomas are broadly classified into open angleand closed angle glaucomas.
Though the major part of glaucoma patients comprise of openangle but the severity of vision loss seems to be more disproportionate inacute angle glaucoma.
In open angle glaucoma the drainage channels are normal orsubnormal but the level of IOP increases in the eye which causes pressure andmechanical effects on the eye ball and hence the damage.
In angle closure glaucoma the drainage channels are affectedand are closed. The path to aqueous drainage is obstructed and hence the levelof IOP increases and damage starts.
The normal range of IOP is from 12-21mmhg. Glaucoma may gosymptom less for a very long period of time and can be detected at veryadvanced stages.
Open angle
Symptoms-usually none
May have loss of central
And peripheral vision later
Signs –elevated IOP
Visual field changes,
Glaucomatous disc changes
Closed angle
symptoms-severe eye ache,
headache, pain blurred vision,
red eye , nausea vomiting,
lights,intense eyeache
Signs-red teary eye,corneal
oedema, closed angle,shallow
AC, mid dilated fixed pupil, iris atrophy
Congenital glaucoma
symptoms-irritability,
photophobia,epiphora
halos 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 includelevobunolol, timolol, betaxolol and metipranol
-alpha agonists
These reduce the production of aqueous humour and increasedrainage. Examples include apraclonidine and brimonidine.
-Prostaglandins like compounds
These increase the outflow of aqueous humour. Examplesinclude latinoprost, bimatoprost and travoprost.
-Miotic agents
These also increase the outflow of aqueous humour. Examplesinclude pilocarpine and carbachol.
-Epinephrine compounds
These compounds such as dipivefrine also increase theoutflow of aqueous humour.
-Oral medications like carbonic anhydrase inhibitor whichdecrease the production of aqueous.
Lasers
Nd Yag laser , selective laser trabeculoplasty(SLT) andargon laser trabeculoplasty are few non surgical less invasive techniques tocontrol intraocular pressure.
Surgery
Trabeculectomy- Surgical procedure to create an alternativefistula for drainage.
Trabeculotomy- procedure used in congenital glaucoma torupture the schelms canal.
Goniotomy- used in congenital glaucoma to incise thetrabecular meshwork.
Drainage device shunt surgeries used in complicatedglaucomas.
Some adjustments which patients with advanced glaucomas needto adapt are improving other senses like hearing, touch, protection from sunand low vision aids.
As I conclude one important thing to my fellow collegues,half of the glaucoma is yet undiagnosed , diagnosing glaucoma at an early stagewill definitely delay or even halt the progression of the disease. The aim isnone of the patients suffering from glaucoma should go blind.
Dr Rayees Ahmad is Assistant Professor Ophthalmology, GMC Anantnag