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Question: What’s the difference between open and closed-angle glaucoma?

Answer: Open-angle glaucoma, also called chronic glaucoma, is what the majority of glaucoma patients suffer from. In this condition, aqueous fluid does not drain well out of the eye. One theory is that the trabecular meshwork filter may have microscopic particles clogging it and slowing down fluid movement.

Closed angle glaucoma, also called acute glaucoma, is an ophthalmologic emergency. This occurs when the iris bows forward and completely blocks fluid access to the trabecular meshwork entirely. The pressure builds up in a positive feedback loop, the patient has excruciating eye pain, and vision is lost quickly.

If you want to use an analogy, think of the eye as a kitchen sink. In chronic open-angle glaucoma, there is debris in the pipes (rust, food, hair) that slows down drainage of fluid. We treat this by giving medications that work like drain-o. With acute glaucoma, there is a rubber stopper floating around in the bottom of the sink that suddenly blocks the drain. Water quickly rises and overflows the sink. We treat this by punching a hole in the rubber stopper (a laser iridotomy).



Comment by gashaw — September 13, 2009

Wow! Thanks! It really helps to start with a cool analogy like that before you start going over the “elaborations” in the text book. Thanks again!

Comment by idrees — March 25, 2010

excellent explanation

Comment by wizzle — April 2, 2010

the answer that i’m scarching for

Comment by vaskar4u@gmail.com — June 30, 2010

Short and sweet. Perfect with the help of analogy, sufficient for people who never studied on this field to understand

Comment by Koei — July 14, 2010

Very nicely explained!

Comment by Manjunath — October 12, 2010

Thank you for this easy-to-understand explanation. I especially love the analogy. This is exactly what I need to under the very basic difference between the two. Thank you once again.


Comment by rhan — November 16, 2010

the kitchen e.g is fantastic ….it make me easier to understand the difference.. thanks

Comment by taimoor ali — December 8, 2010

kuul….Nice answer..

Comment by Mihi — March 23, 2011


Comment by mahia — April 7, 2011

love you all

Comment by mahia — April 7, 2011

this has helped me demystify the mystery that exists between these 2 entities – thank you so much -

Comment by pinky — April 12, 2011

Cheers, great answer !

Comment by Tom — April 15, 2011

Thank you very much for this simple but great information! I will always remember the difference now with that kitchen sink analogy!


Comment by A stressed and confused medical student — June 4, 2011

excellent analogy of open and closed glaucoma.

Comment by babes sicam — August 5, 2011

Thank you very much for u r simple but poerful explanation.

Comment by Vamsi — August 24, 2011

its easy to understand with such daily life examples.. thanks!

Comment by Dr. P — September 21, 2011

Thank you great explanation

Comment by Sameh Bolos — November 6, 2011

Thanks for the wonderful explanation.
1. Does punctum have any role in glaucoma?

Comment by Anant V. Lakhotia — November 18, 2011

Could someone tell me if/how there is a way to tell them apart on fundoscopy images?

Comment by Anita Sholler — November 22, 2011

excellent analogy

Comment by Arshad — November 25, 2011

Great explanation, shortand sweet. Great analogy! Thanks!

Comment by Faria — March 21, 2012

simplest explaination

Comment by Muqaddas — June 25, 2012

Thanks so much. so well done.

Comment by rosemary — July 6, 2012

nicely explained..thanku so much

Comment by bwalya — July 23, 2012

very fudu answer

Comment by hitesh — August 11, 2012

nice explanation

Comment by dr.raj — August 21, 2012

elaborate a little more.plz

Comment by dr.amin — October 20, 2012


1) ACETAZOLAMIDE- carbonic anhydrase inhbitor; that prevents the production of carbonic acid which inturn prevents leakage of sodium ions into the eye were the vitrous humour is produced.


3) MIOTIC AGENTS-eg.PILOCARPINE 2%- That cause miosis(pupil constriction) in order to pull the iris from the trebecular meshwork.

4) ANALGESICS -for the associated pain the patients experiance

5)ANTIEMETICS – for the associated nausea and vomitting (if present)

and note that PILOCARPINE 2% Can be used as a prophylactic agent (ie. to prevent furher damage of glaucoma if the patient is scheduled for surgery…

hope this helps from a pharmaceutical perspective! :)

Comment by NELOSHINI.NAICKER-B.Pharm — November 4, 2012

Excellent. Dr had to punch “my stopper” 13 times on rt eye and 3 times on the left!

Comment by Kennedy — November 15, 2012

couldnt be explained any better,thank you so much

Comment by canberk — November 19, 2012

thank you for that very clear explanation of open vs closed angle glaucoma.

Comment by gwendolyn jordan — December 4, 2012

Hitting da nail at the head Bravo

Comment by Dr Oranuka — February 24, 2013

Thank you for explaining the difference. I didn’t realize there were different types. Your illustration was very helpful as well.

Comment by joanne — March 13, 2013


Comment by Colza — March 19, 2013

thanx it is to understand

Comment by anwaar aslam — March 22, 2013

easy to understand for mbbs students

Comment by anwaar aslam — March 22, 2013

excellent explanation

Comment by Zagy — April 28, 2013

I celebrate u all hw can Stoke cause diplopia? How can it be look in to? Please waiting for answer.

Comment by Dr.further explanation on what causes dilopia. — June 4, 2013

thank you

Comment by terry — August 15, 2013

thumbs UP

Comment by hussein — September 25, 2013

Very easily explained even a layman can understand

Comment by Saxena — November 10, 2013

Very good example used,to understand.

Comment by Ravi — November 14, 2013

so is there an increase in IOP in open angle glaucoma? from what i read they both have an increase. so what about the pressures that differentiate them so distinctively?
Next question: Is Beta Blocker the first line treatment for open angle glaucoma?

Comment by Roxie — December 5, 2013

1. Yes, there is generally an increase in eye pressure for ALL types of glaucoma. People in acute glaucoma often present with eye pressures of 40-70 (i.e. dangerously high) and have severe eye pain because of this. Open-angle glaucoma pressures are usually in the 20-35 range and asymptomatic.

2. Beta-blockers are a fine first-line treatment for open-angle glaucoma. Many eye doctors, like myself, start with prostaglandins (latanaprost) as our first line agent given how effective they are and the minimal systemic side-effects.

Comment by Timothy Root, M.D. — December 6, 2013

That really helps a great deal. Thank you.

Comment by HerMajestytheQueen — January 11, 2014

I am repeating the compliments of previous responders, the analogy given is excellent and easy to understand, I am happy no medical jargon used to confuse the patient. The MD who ansered the question and practices in Houston I will go to him for eye check up.

Comment by jamil azzam — April 2, 2014

Great analogy. I worked for many years in the hospital doing laser procedures, like iridotomies and trabeculoplasties.
This is a great explanation. Wish I could have explained it to the patients like that.

Comment by Mary Rohn — April 25, 2014


Comment by Dr Ravi Krishna — May 6, 2014

Great analogy ,,, makes it extremely to understand… Thanks so very much!!

Comment by teresa — July 11, 2014

thanks for the simple explanation.

Comment by rodah — August 5, 2014

Thanks alot, it makes it more simple to understand.

Comment by rodah — August 6, 2014

I finally understand thanks to this excellent explanation!

With Appreciation!

Comment by KarenCarmel — August 16, 2014

best way of explanation

Comment by dr k k goyal — September 30, 2014

I just had the iridotomy done on my right eye! It was not painful at all. Going for check up tomorrow and then the doctor will do the left eye! I had no symptoms or pain in my eyes! I went for routine check up to my optometrist and she referred me to ophthalmologist! I am glad she did!

Comment by Libor — September 30, 2014


Comment by RENU — October 5, 2014

well explained,,,(y)

Comment by Farzana Yasmeen — February 2, 2015

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