Introduction
The eyes are one of the most sensitive organs of the body. Seeing things around in the environment and enjoying life to the fullest, it all happens due to the presence of eyes and vision. Vision is essential and the presence of a complete or partial absence of vision will impact life big time. Eyes are prone to a lot of infections and injuries due to which the vision is interrupted.
There is a particular visual symptom of a shadow or dark curtain in the path of vision. This could be due to various medical conditions. Retinal tear and detachment, cytomegalovirus retinitis and coronary artery disease are the conditions that show a shadow or dark curtain in the path of vision. This article will explain these conditions in detail.
1) Retinal Detachment
The eye consists of a number of layers like the cornea, iris, lens, pupil, retina, sclera, etc. The light enters the cornea, then passes through the lens. From the lens, the image will be directed towards the retinal layer, from where the image will be sent as signals to the brain through the optic nerve, resulting in an image for vision. When the retina detaches from the wall of the eye, image formation for vision will be interrupted.
Retinal detachment occurs when the retinal layer tries to pull away from the back of the eye and is considered to be an emergency condition and needs to be treated immediately. There are several causative factors.
What Are the Causes of Retinal Attachment?
Based on causative factors, retinal detachment is divided into three categories.
Rhegmatogenous - As a person grows older, the vitreous gel present in between the lens and retinal layers, will become fluid. If a retinal tear is present, this fluid will pass through the tear and get filled-up behind the retina, making the retinal layer detach from the back of the eye. This is the rhegmatogenous type.
Tractional - High uncontrolled sugar levels will affect the blood vessels supplying the retinal layer and form a scar tissue over the retina. This scar tissue gets bigger and tends to pull the retina away from the back of the eye, causing retinal detachment.
Exudative - Eye conditions like uveitis (inflammation of the eyes) causes swelling which gives way to fluid accumulation behind the retinal layer. Even leakage of blood vessels can lead to fluid accumulation behind the retina. These cases will pull away from the retina from the back of the eye, causing retinal detachment.
What Are the Symptoms of Retinal Detachment?
Common symptoms of retinal detachment are,
Increased number of floaters drifting through the path of vision.
A shadow or dark curtain like vision.
Loss of peripheral vision.
Episodes of flashing light.
What Are the Risk Factors for Retinal Detachment?
Aging is one of the most common risk factors for retinal detachment.
Previous injury to the eye can predispose to retinal detachment.
Nearsightedness (myopia) is a condition in which only nearby objects are visible and farther away objects blur. This condition is also believed as a risk factor for retinal detachment.
Retinal detachment also runs in families. So a familial history should be closely watched.
Previous eye surgery like cataracts can also act as a risk factor.
How to Diagnose Retinal Detachment?
A special instrument fixed with bright light will be used to study the retinal layer to assess if there are any tears or cuts present. This procedure will require pupil dilation with a few eye drops to facilitate detailed study.
In case if bleeding is present, then an ultrasound of the eye will be prescribed to scan the eye. Dilating drops will not be required; rather, a numbing formula will be applied to eliminate discomfort.
How to Manage Retinal Detachment?
Pneumatic Retinopexy - The surgeon will blow a bubble of air into the central part of the eye. This bubble will position the detached retina against the wall of the eye, thereby stopping fluid accumulation. Cryopexy - an extreme cold, will be used to seal the tear and cut on the retinal layer. The fluid already accumulated behind the retina gets reabsorbed by the body.
Scleral Buckling - A silicon band or buckle will be placed on the white part of the eye (sclera), thereby positioning the retina against the wall permanently. This buckle will be placed in such a way that vision is not interrupted. The tears and cuts on the retina will be sealed using the cryopexy method.
Vitrectomy - Viterectomy involves the removal of the vitreous body and placing an air or an oil bubble to push the detached retina against the wall. Air bubbles do not need to be removed, as they get reabsorbed. But an oil bubble should be removed after a few months.
How to Prevent Retinal Detachment?
If a person has nearsightedness, it is better to get the eyes checked on a regular basis so as to avoid retinal detachment in the future.
Wear safety goggles to avoid injury to the eyes during sports activities.
2) Cytomegalovirus Retinitis
Cytomegalovirus retinitis is a serious condition of the retinal layer caused by cytomegalovirus, a type of herpes virus .
The symptoms of this condition include,
Shadow appears in the side vision.
Increased appearance of the floaters.
Symptoms start in one eye and then progress to the other. Cytomegalovirus retinitis often presents with retinal detachment. Those affected by human immunodeficiency virus (HIV), cancer and those who underwent an organ transplant are at higher risk for acquiring cytomegalovirus retinitis. A regular eye examination method of dilating the eyes and assessment of the retinal layer will be done to determine the signs of cytomegalovirus. Treatment will mainly include strengthening the immune system. The damaged retinal layer will be treated surgically using a laser. Bringing back lost vision is a bit of a task since the condition will progress amid the treatment.
3) Carotid Artery Disease
Two carotid arteries are present on either side of the neck, which carry blood to the eyes and brain. The blockage of the carotid artery is known as carotid artery disease. A blocked carotid artery will not supply the eyes and brain with enough blood, thus hampering their function. A classic warning sign of a blocked carotid artery is the shadow or dark curtain in the vision field. This sign indicates immediate treatment.
Conclusion:
A shadow or dark curtain is predominantly a sign or a symptom of an underlying condition. Getting back lost vision completely depends on the severity of the condition and how quickly it is treated. Consulting with an ophthalmologist as soon as the first sign appears, will prevent major complications.
