Introduction:
The eyeball is a critical area where minute irregularities or deviations can precipitate complex ophthalmic disease conditions. When the pressure within the eyeball changes, it can considerably impact the person's vision. Ocular hypotension is one such condition where the pressure falls dramatically.
What Is Ocular Hypotension?
Ocular hypotension is a peculiar condition where the affected person elicits a collapse in eye pressure. Ocular hypotension is precipitated when the pressure falls below the lower limit, typically below 6.5 mmHg (millimeters of mercury). The fall in the pressure happens due to certain eye surgeries, injuries, or impacts over the eye. Though it can threaten vision, certain studies concluded that occasionally patients are reported to have no visual disparities despite having collapsed intraocular pressure. Ocular hypotension is widely known by the synonym ocular hypotony.
What Is Intraocular Pressure?
The human eye encloses a certain amount of fluid within it, contributing to the eyeball's shape. Vitreous and aqueous humor are the two distinct eye fluids, where the vitreous humor spreads over the back side while the other spread over the front region. These fluids are always in constant movement and apply pressure on the eye's interior surface. This pressure is technically known by the term intraocular pressure. The usual range of intraocular pressure is determined to be within 10 to 20 millimeters of mercury (mmHg). The production of the fluid should be in synchrony with the outflow (drainage) of the liquid. Any disparity in the production and drainage results in either exaggerated or deficient fluid collection within the eye. Exaggerated fluid buildup projects a rise in the intraocular pressure while its collapse marks down the intraocular pressure. Both conditions are capable of creating visual troubles.
What Causes Ocular Hypotension?
Though collapsed intraocular pressure is reported to be the prime triggering factor for ocular hypotension, a spectrum of causes brings about fluctuations in intraocular pressure. Some of the routinely encountered reasons include the following:
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Compromised Fluid Production: A remarkable compromise in aqueous humor production projects a drastic collapse in the intraocular fluid level and eventually gives rise to a drop in the intraocular pressure. Any inflammation like uveitis within the eye can negatively impact liquid production. In addition, ocular diseases like ocular ischemic syndrome (due to hampered blood flow to the eye) and proliferative vitreoretinopathy (disunion of the photosensitive retinal layer) also bring down the aqueous humor production. Certain drugs that come under the aqueous humor suppressants also induce the collapse of fluid output. Similarly, cyclo-destructive procedures (using lasers or liquid nitrogen) wreck the ciliary body (site of fluid production), directly impacting fluid production.
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Exaggerated Fluid Drainage: Enhanced outflow of the aqueous humor is often encountered as a complication that arises following ocular surgeries like glaucoma, corneal, and vitreoretinal surgeries (for disorders involving the retina). Certain glaucoma drainage devices placed for the correction of glaucoma enhance the drainage and eventually precipitates ocular hypotension. Open globe injury and blunt trauma also facilitate the drainage of fluid.
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Systemic Conditions: Certain systemic conditions like elevated urea level (uremia), diabetic coma (collapse precipitated by exaggerated or diminished sugar level), and severe dehydration also contribute to ocular hypotension. Inborn conditions like Marfan syndrome (troubles in bones and heart) elicit fragility of the outer protective scleral layer, facilitating the development of ocular hypotension. Pregnancy, though it is not a disease condition, at times, enhances the risk of ocular hypotension.
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Drug-Induced: Certain medicines like antihypertensives, antiviral, hyperosmotic agents, nitrates, and carbonic anhydrase inhibitors are known to impact intraocular pressure. These drugs can bring about ocular hypotension by influencing intraocular pressure.
What Are the Signs and Symptoms of Ocular Hypotension?
Though ocular hypotension compromises vision, certain patients sometimes remain without any visual impairment. Hence the, ocular hypotension does not need to elicit pronounced symptoms. However, the manifestations of ocular hypotension vary with the underlying factor that induces collapse in intraocular pressure. Some of the routinely encountered manifestations include the following:
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Compromised Vision: Vision loss is the most frequently encountered manifestation of ocular hypotension. The compromise in the vision may develop all of a sudden, or it may develop gradually over time.
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Diminishing Visual Acuity: Images appear disfigured and deformed. The person elicits challenges in seeing the fine details of an object.
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Painless: Ocular hypotension is relatively painless unless associated with a trauma or injury to the eyeball.
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Impaired Globe Stability: Disruption in the stability and integrity of the eyeball in the form of corneal rupture, globe perforation, and seepage from the bleb are also encountered in ocular hypotension.
How Is Ocular Hypotension Diagnosed?
History of ocular surgeries or impact on the eyeball often gears up the diagnosis. An in-depth patient medical history analysis is mandatory to clear the path toward the final diagnosis. In addition, the medicines currently undertaken by the patient should also be looked over to rule out the presence of drugs capable of bringing about ocular hypotension. Apart from the medical history, certain investigatory tests are carried out to confirm the diagnosis of the condition. Routinely advised diagnostic tests include:
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Tonometry: It assesses the intraocular pressure; hence, any deviation from the normal limit can be appreciated easily.
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Seidel Test: It is employed to check for fluid seepage and facilitates the detection of globe perforation.
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Slit Lamp Biomicroscopy: It is widely recommended to look for signs of inflammatory eye changes.
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Ultrasound Biomicroscopy: It is advised to detect abnormalities associated with the ciliary body.
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Fundus Fluorescein Angiography: It helps in identifying leakage. In addition to fundus fluorescein angiography, certain other investigatory tests like optical coherence tomography are also advised in some instances to identify the underlying cause.
What Are the Treatment Interventions Available for Ocular Hypotension?
The treatment for ocular hypertension is explicitly designed according to the cause. Diagnostic tests not only guide diagnosis but also reveal the real cause behind the condition, enhancing the treatment strategies. There are two major approaches for treating ocular hypotension - conservative and surgical.
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Conservative Approach: Ocular hypotension with seepage of fluid is often tackled with the help of compression sutures, cyanoacrylate glue, and blood injections. Medicines like nonsteroidal anti-inflammatory drugs and corticosteroids are preferred for an associated inflammatory condition.
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Surgical Approach: It is a more comprehensive treatment strategy and is considered only when a conservative approach fails to elicit fruitful results.
Conclusion:
Though ocular hypotension is unfamiliar, it can bring about grave visual complications. The collapse in intraocular pressure can wreck a person's vision. It is occasionally reported following ocular surgeries; however, trauma and other conditions may also trigger it. Diverse factors contribute to the development of ocular hypotension; hence treatment is planned by considering the cause.
