NF2 may be diagnosed earlier in children with a family history of the disease, as a result of early screening, or in those who initially present with Diplopia or Amblyopia (lazy eye), and/or vision loss.
There are two major types of Diplopia (double vision): Binocular and Monocular.
Binocular Diplopia is a more common type of double vision. It occurs as a result of the misalignment of both eyes due to functional problems within the vision system. This could be due to stroke(s), aneurysm(s), increased intracanial pressure from a brain tumor, or increased pressure inside the brain from trauma/ bleeding/ infection, and/or any extraocular muscles nerve palsy (intracranial nerves 3, 4, and 6), etc.
Some Causes of Binocular Diplopia:
- Ocular Misalignment – If a muscle in one eye is weak, that eye can’t move smoothly with the healthy eye. Gazing in directions controlled by the weak muscle causes double vision.
- Increased pressure inside the brain or spinal cord caused by either a Brain tumor or Hydrocephalus (ie. the flow of CSF is blocked).
- A tumor behind the eye that prevents the normal motion of the eyeball.
- Palsies of cranial nerves that control eye movement:
- Nerve III: Eyelid droop, eye deviated laterally and down, sometimes pupillary dilation.
- Nerve IV: Vertical diplopia worse on downward gaze (patient tilts head to improve vision).
- Nerve VI: Eye deviated medially, diplopia worse on lateral gaze (patient turns head to improve vision).
Monocular diplopia occurs when something (Cataract, or Corneal shape problems such as keratoconus, or surface irregularity, or scarring, or an uncorrected refractive error usually astigmatism) distorts light transmission through the eye to the retina, resulting in more than 2 images simultaneously. One of the images is of normal quality (eg, brightness, contrast, clarity); the rest are of inferior quality. This type of diplopia (a structural defect in the eye’s optical system) is a less common cause of double vision.
Some Causes of Monocular Diplopia:
- Cataracts are the most common problem when the eye’s lens causes double vision or a refractive error. This often results in light from an object, splitt ing into two images by the defect in the lens.
- Corneal scars can distort the surface of the cornea, creating unequal visual images.
- Dryness of the cornea can create double vision.
Special prism glasses and/or eye patch are often used to minimize the effect of double vision.
Diplopia may be improved with eye exercises that help in some cases.
- About Double Vision (Diplopia) – Optometrists Network – There are two possible and different causes: The most common cause of double vision is misalignment of the two eyes due to functional problems in the visual system. This web page contains complete information on this type of double vision: binocular diplopia. A structural defect in the eye’s optical system is a much less common cause of double vision. Cataracts, for example, might cause such a defect. In this case, diplopia can appear in only one eye; this is called monocular diplopia.
- Double Vision (Diplopia) – WebMD – Double vision, or diplopia, is a symptom to take seriously. Some causes of diplopia are relatively minor, but others need urgent medical attention. WebMD takes a look at the causes, symptoms, and treatments for double vision.
- Diplopia – University of Michigan Kellogg Eye Center – Monocular diplopia persists when one eye is covered. It is caused by an optical aberration (cataract, uncorrected refractive error, presbyopia, keratopathy). Binocular diplopia disappears when either eye is covered. It results from misalignment of the eyes, and may be caused by: a central nervous system lesion, an ocular motor nerve lesion, a neuromuscular junction lesion, extraocular muscle lesion.
- Diplopia – Medscape – The term diplopia is derived from 2 Greek words: diplous, meaning double, and ops, meaning eye. Diplopia (double vision) is a common subjective complaint, or diplopia may be elicited during the course of an eye examination. Diplopia is often the first manifestation of many systemic disorders, especially muscular or neurologic processes. An accurate, clear description of the symptoms (eg, constant or intermittent; variable or unchanging; at near or at far; with one eye [monocular] or with both eyes [binocular]; horizontal, vertical, or oblique) is critical to appropriate diagnosis and management.
- Diplopia (Double Vision) – University of Michigan Kellogg Eye Center – If you see two of whatever you are looking at, you may have a condition known as diplopia, also referred to as double vision. Diplopia may be the result of a refractive error, where light from an object is split into two images by a defect in the eye’s optical system. Cataracts might, for example, cause such a defect. Diplopia may also result from failure of both eyes to point at the object being viewed, a condition referred to as ocular misalignment. In normal vision, both eyes look at the same object. The images seen by the two eyes are fused into a single picture by the brain. If the eyes do not point at the same object, the image seen by each eye is different and cannot be fused. This results in double vision.
- Diplopia – eyerobics – Diplopia is double vision caused by a defective function of the extraocular muscles or a disorder of the nerves that innervate (stimulate) the muscles. The images seen by the two eyes are fused into a single picture by the brain. If the eyes do not point at the same object, the image seen by each eye is different and cannot be fused. This results in double vision.
- Diplopia (Double Vision) – The Merck Manual – Double vision (diplopia) is seeing two images of one object. Double vision may occur when only one eye is open (monocular diplopia) or, more commonly, when both eyes are open (binocular diplopia). Binocular double vision disappears when either eye is closed. Other symptoms, such as eye pain, bulging eye, or muscle weakness, can be present depending on the cause of double vision.
- Diplopia (Double Vision) – The Merck Manual (Professional) – Diplopia is the perception of 2 images of a single object. Diplopia may be monocular or binocular. Monocular diplopia is present when only one eye is open. Binocular diplopia disappears when either eye is closed.
- Diplopia – lowvision.org – Double vision (diplopia) is one of the most troublesome visual disorders a patient can experience. The ability to read, walk and perform common activities is suddenly disrupted. The management of double vision may include prisms, orthoptics, therapy, eye muscle surgery and occlusion. The goal is to establish clear binocular single vision. Double vision management may require any combination of these therapies. Since some patients may recover function over time, surgery may be not be considered initially. Prisms should be used when it aids the patient in eliminating double vision. Press-on prisms may be applied to the patient’s lenses to reduce double vision. Orthoptic therapy may be indicated in many cases. When diplopia causes significant discomfort, and is not responsive to other therapies, occlusion may be used. Unfortunately many clinicians are still prescribing black “pirate” patches. These are rarely required. New methods of occlusion are now available.
- Double Vision (Diplopia) – MedicineNet.com – Opening your eyes and seeing a single, clear image is something you probably take for granted. But that seemingly automatic process depends on the orchestration of multiple areas of the vision system. They all need to work together seamlessly.
- Double Vision or Diplopia – EyeHealthWeb – Diplopia, better known as double vision, is a visual symptom that can be minor or serious. Many of us take advantage of opening our eyes and seeing a single, clear image. It’s an automatic process that is working within our vision system; everything works together and there is no problem. However, when something goes wrong and we begin to see double images, it could be a sign of a serious underlying problem and medical attention should be sought after immediately.
- Chapter 113 – Diplopia – NCBI Bookshelf PMID:21250061 – The law of projection of images establishes that an object forming its image on any point in the retina is projected to a point in space directly opposite.