Metamorphopsia is a defect in vision in which lines appear wavy, parts of the line appear blank and flat surface bend. A patient with metamorphopsia, for instance, sees a tree bending despite the fact that it is perfectly straight. Patients with this disorder must see an ophthalmologist right away to check their condition. In some cases, metamorphopsia is underlying symptom of more serious cases that can further damage the sense of vision of an individual.
Anatomy of the Eye
The human eye is very important because it gives us the sense of sight, which is one of the five senses of a typical human being. Vision is the sense that has been studied most. The tracts inside the eye carry information that we see to our brain, in which the image is being processed.
The adult eye is a sphere that measures about 1 inch (2.5 cm) in diameter. Its wall is made up of three tunics or coats and its inside is occupied with fluids known as humors that help to maintain its shape. The lens, the main focusing apparatus of the eye, is supported upright inside the eye and is composed of two chambers.
Picture : Eye Anatomy
Image source : biographixmedia.com
Three Tunics of the Inside the Eyeball
The remotest tunic, the protective sclera is thick, whitish connective tissue. Also called the fibrous tunic, the sclera is seen as the whitish part of the eye. Its middle frontalportion is modified so that it is crystal clear. The cornea, a transparent window, where the light passes through, is composed of thousands of nerve endings especially pain receptors which is it hurts when an inanimate objects touches the cornea.
In the middle portion of the eyeball is the choroid, atunic thatis well-supplied with blood andholds a darkish pigment. In the anterior portion, the choroid accommodates two structures, which are the ciliary body and the iris. The lens is located in the ciliary body. In the center of the iris, the pupil is located, where the light passes.
The deepest tunic of the eye is the fragile whitish retina, which extends anteriorly only to the ciliary body. The retina is composed of many receptor cells, the rods and cones. Rods and cones, which are commonly known as photoreceptors, react to light.
Light that enters the eye is focused on the retina by the lens, a flexible biconvex crystal-like structure. The lens is held upright in the eye by suspensory ligaments attached to the ciliary body.
How the Light Passes Through the Eye
When light passes from one matter to another that has a different thickness, its speed changes and its rays bent, or refracted. Light rays are bent in the eye as they encounter the cornea, aqueous humor, lens and vitreous humor.
Light waves the eye through the cornea and then passes to the pupil. At first, the light waves are twisted in the cornea then it progress to the crystalline lens then to the nodal point, which is located behind the lens. The image produce at the back of the lens is upside-down. Afterwards, the light continues to the vitreous humor then back to retina which is at the back of the vitreous. The macula, which is located in the center of the retina, provides the best vision in any location of the retina. Inside the retina, the light waves are transformed into electrical signals then transported to the occipital cortex through the optic nerve. Here, the electrical signals are interpreted by the brain as an image.
Causes of Metamorphopsia
1. Macular Degeneration
Most of the people who develop metamorphopsia, acquire this as a symptom of macular degeneration particularly age-related macular degeneration usually accompanies bychoroidal neovascularization. Macular degeneration is a condition in which it affects old people particularly 50 years old in which there is a loss of vision in the center of visual field of the eye due to the damage to the retina.
2. Retinal Detachment
This is a condition in which the retina separate from its supporting layers. When this happens, the eye is unable to see things clearly and metamorphopsia happens. Retinal detachment can be caused by head trauma or injury to the infected eye, diabetes, complication in surgery, family history of retinal detachment and a bad case of nearsightedness.
This happen when blood vessels in the brain dilate and stimulate the release of hormones in the brain. These hormones activate pain receptors thus causing pain. The pain that a person experience when he is having a migraine causes visual problems that can attribute to the symptoms of metamorphopsia. The symptoms are temporary but there are others who frequently experience migraines.
4. Macular Hole
Can result to symptoms of metamorphopsia, blurring of vision, and difficulty in reading. This usually happens to people who are over the age of 60. There are many causes for the progress of hole in the macula such as retinal detachment, underlying diseases, eye injuries, and many more.
Signs and Symptoms of Metamorphopsia
- Straight lines appear wavy or curly
- Flat surfaces are seen as curved
- A grid of straight lines may appear blank
Picture 1 : Normal Vision
Image source : retinavitreouscenter.com
Picture 2 : Metamorphopsia in left half field of vision (defective vision)
Image source: retinavitreouscenter.com
Treatment of Metamorphopsia
The treatments available for this condition depend on the underlying causes. To properly get a treatment, a patient will need to see an ophthalmologist first and undergo an ophthalmologic examination.
If the cause of distorted vision or metamorphopsia is bleeding which is usually seen in patients with macular degeneration, laser photocoagulation can be an option to prevent further hemorrhage. Furthermore, if retinal detachment is the culprit for causing symptoms of metamorphopsia then surgery must be considered as a priority treatment. Scleral buckling, pneumatic retinoplexy and vitrectomy are the surgeries that can treat retinal detachment. However, if the cause of metamorphopsia is only macular hole, it can be treated using cryotherapy to prevent a full-scale retinal detachment.
Lastly, migraines can be cured using pain medications such as acetaminophen and NSAIDs or other non-medication alternatives such as relaxation techniques, getting enough sleep, avoiding smoking, and avoiding foods high in tyramine.