What Is Subhyaloid Hemorrhage?
Subhyaloid hemorrhage refers to a condition in which blood collection occurs in the eye's macular region. This leads to a restricted retinal detachment from the vitreous, which may cause instant (within seconds to minutes) and critical vision loss. A biomicroscopy or slit-lamp examination disclosed that the bleeding is acute and dome-shaped. However, its exact location is usually unrevealed. In a scientific study, the researchers recognized the hemorrhage site in their patients as a sub-internal limiting membrane (ILM) cleavage plane. Based on this finding, subhyaloid hemorrhage exists between the vitreous’ posterior limiting layer and the retina’s internal limiting membrane (ILM). Subhyaloid hemorrhage is rare. Subhyaloid hemorrhage appears as a dark-red mass, usually circular in shape, located at the posterior pole and affecting a large area. When the hemorrhage is extensive, it is single or multiple small areas of bleeding may be present.
What Are the Other Names for Subhyaloid Hemorrhage?
Premacular and pre-retinal hemorrhages were often used to describe this condition and sub‐ILM hemorrhage, but it is right to call them so only if the bleeding is present anterior to the ILM. The basement membrane of the Mueller cells constitutes ILM, so bleeding posterior to the ILM occurs within the neuroretina and can be known as macular or sub‐ILM hemorrhage. Subhyaloidal hemorrhage has also been denoted as hyphema posterior, and sub‐ILM hemorrhage as submembranous hemorrhage, hemorrhagic detachment of the ILM, or hemorrhagic macular cyst. However, the term ‘cyst’ cannot be used here as it means a hollow or a fluid-filled cavity lined by epithelium or endothelium. Hence, the established term is ‘macular hematoma.’ In subhyaloid hemorrhage, as the patient’s head position changes, the hemorrhage gradually moves toward the bottom of the eye. On the other hand, sub-ILM hemorrhage remains stationary. These descriptions further distinguish subhyaloid hemorrhage from sub‐ILM hemorrhage.
What Are the Manifestations of Subhyaloid Hemorrhage?
The signs and symptoms of subhyaloid hemorrhage include:
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Red-tinted vision.
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Increased eye floaters.
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The appearance of vision cobwebs.
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Distorted or blurred vision.
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Haziness and shadows in vision.
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Peripheral vision has rapid eye flashes.
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Immediate blindness.
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Headache.
What Are the Causes of Subhyaloid Hemorrhage?
To come to an appropriate treatment plan, it is imperative to find out the cause of subhyaloid hemorrhage. The causes of subhyaloid hemorrhage are grouped as follows:
Primary Causes:
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Valsalva Retinopathy - It is a particular type of retinopathy in which pre-retinal hemorrhage occurs due to increased intrathoracic pressure.
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Terson Syndrome - It is an oculocerebral syndrome involving retinal and vitreous hemorrhages along with spontaneous subarachnoid or subdural hemorrhage.
Secondary Causes:
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Hypertension.
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Retinal artery or vein occlusion.
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Proliferative diabetic retinopathy.
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Retinal macroaneurysm.
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Polypoidal choroidal vasculopathy.
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Chorioretinitis.
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Blood disorders like leukemia and chemotherapy-induced pancytopenia.
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Shaken baby syndrome.
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Age‐related macular degeneration.
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Trauma.
Which Investigations Help Diagnose Subhyaloid Hemorrhage?
A detailed history of general and medical histories comprising medical conditions and systemic disorders, drug use, abuse, injury or trauma, Valsalva exercises, etc., is recorded. Further, the following tests are used for diagnosing subhyaloid hemorrhage:
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Fundoscopy: It is a test by which the fundus of the eye is checked with the help of a magnifying lens through a dilated pupil.
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Biomicroscopy or Slit-lamp Examination: It is the basic diagnostic tool used to examine the eyes' anterior segment. It has a combination of a microscope with a very bright light.
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OCT (Optical Coherence Tomography): It is an imaging technique used to have an idea of the back of the eye by using reflected light.
In funduscopy, subhyaloid and sub-ILM hemorrhages portray a similar appearance, with ILM reflecting the light and giving a glistening light reflex. It is impossible to differentiate subhyaloidal and macular hemorrhages clinically with a fundoscopy and slit lamp test, so OCT is the only helpful method for this type of ocular hemorrhage. However, an OCT scan also has limitations because the hemorrhage drastically diminishes the underlying structures. Preretinal, subhyaloid, and vitreous hemorrhages have great control of gravity over them. Preretinal and subhyaloid hemorrhages appear darker at the bottom of the bleeding. The blood settles here with a marked horizontal line at the top called a “D” or boat shape. OCT fails to illustrate whether the location of the hemorrhage is subhyaloidal or sub‐ILM. Also, it does not distinguish between subhyaloidal and subretinal hemorrhage. Therefore, there is a substantial need to produce more advanced diagnostic techniques for better treatment decisions and outcomes.
What Are the Treatment Options for Subhyaloid Hemorrhage?
Various treatment choices are available for subhyaloid hemorrhage. However, the main focus of the treatment remains hemorrhage removal, yet, certain essential decision-affecting factors for the treatment include the following:
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Any underlying disease.
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Age of the patient.
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Duration since hemorrhage onset.
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Size of the hemorrhage.
The different treatment methods are:
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Spontaneous Hemorrhage Reabsorption or Resolution: The hemorrhage is left untouched and observed for up to three months for its spontaneous clearing. However, there is a controversy over this method, as hemorrhage persistence may cause irreversible impairment of the retina and may lead to permanent blindness.
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Conservative Laser Drainage: It is recommended within the first three to four days following bleeding. It allows the collected blood to drain into the vitreous cavity by rupturing the posterior hyaloid or ILM with Nd: YAG laser, ensuring its removal and improvement in vision. This procedure is also known as ‘laser membranotomy’ and ‘laser puncturing.’ It is safe and has rare critical complications.
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Use of Recombinant Tissue Plasminogen Activator and Gas: This technique results in vitreous separation and blood distribution in the vitreous cavity and successfully treats subhyaloid hemorrhage.
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Pars Plana Vitrectomy (PPV): It provides instant hemorrhage resolution and close examination of the hemorrhage location and its surgically removed anterior wall. It also yields an excellent visual recovery if no procedure‐related complications are accompanied. Despite being a routine treatment approach, it has many adverse effects and risks like nuclear sclerotic cataract formation, particularly in elderly patients, intraoperative retinal breaks, postoperative proliferative vitreoretinopathy, etc. However, an early resolution of the vitreous hemorrhage by surgery produces notable and instant vision improvement and may also avoid longstanding hemorrhage complications.
Conclusion:
Subhyaloid hemorrhage is a type of retinal hemorrhage that occurs occasionally but it usually demands immediate treatment, so a quick visit to an ophthalmologist is advised upon the appearance of its first manifestation. The several available treatment choices provide prosperous results. Additionally, more research-based scientific studies are required to develop drugs that can allow vision recovery and patient rehabilitation by minimally invasive techniques and with the least potential side effects.
