Intraocular Pressure and Glaucoma

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Hello to all,


It is another beautiful day today and a wonderful time and opportunity to come your way once again with another lesson or discussion on our ocular health. I find great pleasure in knowing that my readers are learning something new about their eyes every day and that this knowledge would go on to make our work as healthcare practitioners easier as our patients understand better.

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In our previous discussion we looked at the topic Diabetic Cataract where we came to understand one of the detriments of diabetes on the eye which is accelerated cataract formation and development, we also looked at how and why this happens and the best way to go about managing this condition.

For today, I want to look at the pressure that exists within the eye also known as intraocular pressure or IOP, and how it relates to Glaucoma. I am doing this because I had a patient today at the hospital who was not a glaucoma patient but was on glaucoma treatment due to a misunderstanding she had from her previous consult and how she decided to take matters into her own hands. Hopefully, none of you dear readers will be victims of this incident.


Intraocular Pressure


Just as the name implies, when we talk about intraocular pressure we are talking about pressure within the eye itself or eyeball if you would want to look at it that way. Generally, our system is maintained by some amount of pressure which ensures the movement or flow of fluid up and down the various systems within our body. This pressure also helps in the delivery of food nutrients through the blood as well as the removal of waste.

Ideally, this pressure should fall within a range, of the average human systemic pressure, 120/90 is a good standard where 120 represents the systolic pressure and 90 is the diastolic pressure. This pressure is regulated by our heart as it continues to pump blood through our entire body. When this goes haywire and the pressure soars we could end up with the condition known as hypertension and in the same vain when it goes too down we end up with hypotension, both of which are serious conditions with lots of health implications and may even be considered an emergency in some situations.

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Now we are not dealing with systemic pressure today however I wanted us to get the idea of how pressure is important in our systems and the fact that they exist to serve a particular purpose. And just as pressure exists in our systems to keep things going, so does it in our eyes to maintain the stature and structure of the eyeball and its integrity. The pressure in the eyeball ought to be within a range of 10mmhg to 20mmhg.

When the pressure falls below this range a situation known as hypotony may occur and the eyeball may fall within itself and it losses the pressure holding it together, in the situation where it rises above the range damage to the various structures within the eyeball may occur, mostly what tends to suffer from high IOP is the optic nerve whose cells end up getting irreversibly damaged. The vessels within the eye may also suffer; in some cases, the very small ones may start to rupture and bleed into the eye.


IOP & Glaucoma Relation


So you may be wondering how the pressure in the eye as we discussed is related to the condition known as glaucoma. Well, glaucoma is a neurodegenerative condition where the optic nerve experiences apoptosis or cell death mostly as a result of a rise in IOP, however, it may not be limited to only the rise in pressure because other signs of the damage may still persist in the eye whereas the pressure may still be within range. This situation is referred to as normal tension glaucoma.

The diagnosing of glaucoma can be a bit tricky and requires the expertise of an Optometrist or an Ophthalmologist to ascertain whether we are looking at Glaucoma or something else. Tests such as the Retinal Nerve Fiber Layer analysis, OCT, and VFT may be requested to ascertain the extent of the damage and whether the damage truly follows the glaucomatous pattern.

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The issue with glaucoma and IOP is that sometimes our IOPs can shoot up much like your systemic pressure increases after a run, strenuous activity, or tiring day. This does not mean that you are a hypertensive patient however if the pressure is too high within that short period you may be given hypertensive medication to bring it down, you do not have to continue the medication after the pressure is normalized. And so if you go to the hospital and perhaps your Optometrist mentions that your pressure is a bit up and gives you antiglaucoma drugs to bring the pressure down, it is not a glaucoma diagnosis.

You ought to go back for review and not continue to get more of the drugs, diagnosing yourself as a glaucoma patient and telling every eyecare practitioner you meet that you have glaucoma which is what the patient that I introduced earlier was doing. Luckily, I got to stop her at a good point lest the pressure drops below the range and hypotony sets in.

And so please note that you can have your intraocular pressure high and not have glaucoma, you can also have your pressure within range and still have glaucoma and as it is in most cases, you can have the pressure high due to glaucoma. The best way to go about it is always to talk to your Optometrist, and ask if you are uncertain well to avoid the use of not prescribed medication for the eye. This includes using your own judgment to get more of an eye drop simply because it was given to you during your previous visit. You could be causing more damage than good.


Conclusion


The eye is a delicate organ that responds to the minute changes that happen within your entire system, which is what makes it a good diagnostic tool for physicians, a lot of times damage to the,e eye especially the nerves tend to be irreversible and so we ought to be particular about our eye health.

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Avoid over-the-counter drugs, always seek professional counsel, you are entitled to the answers to your questions and so do not be afraid to ask when you visit the eyecare facility always do well, eat healthily and stay healthy. Love your eyes, and stay safe. Thanks for your time.


Further Reading

Sultan MB, Mansberger SL, Lee PP. Understanding the importance of IOP variables in glaucoma: a systematic review. Surv Ophthalmol. 2009 Nov-Dec;54(6):643-62. DOI: 10.1016/j.survophthal.2009.05.001. Epub 2009 Aug 8. PMID: 19665744.

Pellegrini F, Cuna A, Cirone D, Ciabattoni C, Caruso E, Interlandi E, Zappacosta A. Clinical Reasoning: Wilbrand's Knee, Scotoma of Traquair, and Normal Tension Glaucoma. Case Rep Neurol. 2022 Aug 30;14(2):341-347. DOI: 10.1159/000525799. PMID: 36160657; PMCID: PMC9459516.

Palmberg PF. What Is It About Intraocular Pressure That Matters in Glaucoma Progression? JAMA Ophthalmol. 2022 Oct 27. DOI: 10.1001/jamaophthalmol.2022.4464. Epub ahead of print. PMID: 36301536..

Nishida T, Moghimi S, Chang AC, Walker E, Liebmann JM, Fazio MA, Girkin CA, Zangwill LM, Weinreb RN. Association of Intraocular Pressure With Retinal Nerve Fiber Layer Thinning in Patients With Glaucoma. JAMA Ophthalmol. 2022 Oct 27. DOI: 10.1001/jamaophthalmol.2022.4462. Epub ahead of print. PMID: 36301523.



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Glaucoma affects lots of people! Very common
!1UP


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