A curtain in vision refers to a loss of vision in parts of the visual field. It creates a curtain-like effect where vision is partially obstructed. Curtains in vision can take various forms and have different causes. The most common types are altitudinal field defects, hemianopia, quadrantanopia, and scotomas. Identifying the specific characteristics of a curtain in vision can help determine the underlying cause.
Types of Curtains in Vision
Altitudinal Field Defects
Altitudinal field defects cause loss of vision in the upper or lower visual fields. In upper altitudinal defects, also called superior field defects, vision loss occurs in the upper half of vision. Lower altitudinal or inferior field defects cause blindness in the lower visual field. The curtain drops across the horizontal midline, creating a sharp demarcation between seeing and non-seeing areas.
Some common causes of altitudinal field defects include:
– Retinal vascular occlusions – Blockages in veins or arteries supplying the retina can damage sections of the retina and cause corresponding vision loss. Central retinal artery occlusions typically cause upper altitudinal defects. Central retinal vein occlusions more commonly cause lower altitudinal defects.
– Optic neuropathies – Diseases affecting the optic nerve, like glaucoma, can preferentially damage nerve fibers carrying information from upper or lower retinal fields. This leads to altitudinal vision loss.
– Compressive lesions – Tumors, aneurysms, or other masses pressing on the anterior visual pathway can produce altitudinal defects. The location of the compression determines whether upper or lower field loss occurs.
Hemianopia
Hemianopia refers to blindness in half of the visual field. It is divided into:
– Homonymous hemianopia – Loss of vision on the same side in both eyes. This is the most common form of hemianopia.
– Heteronymous hemianopia – Vision loss on opposite sides in each eye. This is less common.
In homonymous hemianopia, the curtain runs vertically down the middle splitting vision in two. Heteronymous hemianopia has two curtains creating blindness in the outer or inner visual fields.
Causes of hemianopic field defects include:
– Strokes – Vascular lesions damaging the visual cortex or optic radiations produce homonymous hemianopia reflecting the unilateral damage. Strokes rarely cause heteronymous defects.
– Brain tumors – Tumors compressing optic tracts or visual cortex can also cause homonymous hemianopia. The side and location of the tumor matches the visual field loss.
– Traumatic brain injury – Impacts causing damage to the occipital lobes or posterior visual pathways lead to homonymous hemianopia. The side corresponds to the site of injury.
Quadrantanopia
As the name suggests, quadrantanopia refers to vision loss in a quarter or quadrant of the visual field. This appears as a curtain obscuring one of the four quadrants – upper temporal, upper nasal, lower temporal, or lower nasal.
Common causes of quadrantanopia include:
– Retinal ischemia – Reduced blood supply to sections of the retina due to vascular occlusion affects corresponding visual fields. The retinal quadrants affected determine which visual field quadrant is lost.
– Optic neuropathy – Glaucoma and other optic nerve diseases can damage groups of nerve fibers carrying information from one quadrant of vision. This produces quadrantanopic defects.
– Brain lesions – Tumors or vascular damage affecting the optic radiations or visual cortex lead to blindness in parts of the visual field related to the location of the lesion.
Scotomas
Scotomas are isolated islands of vision loss surrounded by normal sight. They can occur anywhere in the visual field and have variable size and shape. Scotomas may be central, paracentral, arcuate, or ring-shaped. The curtain effect is created by the island of blindness within normal vision.
Causes of scotomas include:
– Macular degeneration – Central and paracentral scotomas occur due to damage to the macula from age-related macular degeneration or other conditions.
– Optic neuropathy – Glaucoma and other optic nerve diseases produce arcuate scotomas reflecting nerve fiber bundle damage.
– Retinal lesions – Scars or other lesions affecting the retina create corresponding scotomas.
Characteristics of Curtains in Vision
The specific features of a visual field curtain can provide clues about the underlying cause:
Location
– Altitudinal – Suggests retinal or optic nerve disease
– Vertical hemianopia – Indicates brain lesion on opposite side
– Quadrantic – Points to localized retinal or optic nerve damage
– Central/paracentral – Implicates macular pathology
Edges
– Distinct margins – More likely from vascular damage
– Indistinct margins – Often seen in neural compression/tumors
Onset
– Sudden – Vascular occlusion, stroke, or trauma
– Gradual – Typical of glaucoma, tumors, neural degeneration
Progression
– Static – Usually vascular causes
– Slow progression – Characteristic of glaucoma and neural lesions
– Rapid progression – Suggests rapidly growing lesion/tumor
Associated symptoms
– Unilateral headaches – Can indicate tumor or stroke
– Light flashes/floaters – Often retinal vascular disease
– Visual distortion – Typical of macular conditions
Associated medical conditions
– Hypertension, diabetes – Increase risk of retinal ischemia
– Previous strokes – Raise probability of vascular lesion
– History of trauma – Links visual loss to prior injury
Diagnostic Evaluation
A thorough medical history and eye exam are the first steps in evaluating curtain-like vision loss. Additional diagnostic tests help confirm the cause:
Visual field testing
Specialized perimetry tests map out areas of blindness and further define the characteristics of visual field defects. Automated perimetry uses computerized projections to test vision in different areas of the visual field. Manual kinetic perimetry involves moving test objects from non-seeing to seeing areas to outline field deficits. These tests plot the shape and borders of curtain defects.
| Test | Information Provided |
|---|---|
| Visual field testing | – Maps areas of blindness – Defines edges and extent of defects |
| Optical coherence tomography (OCT) | – Assesses retinal thickness and pathology |
| Fundus photography | – Documents optic nerve and retinal abnormalities |
| Fluorescein angiography | – Highlights retinal vascular abnormalities |
| Neuroimaging | – Identifies lesions in visual pathways and brain |
Optical coherence tomography (OCT)
OCT uses light waves to produce cross-sectional images of the retina. This allows detailed evaluation of retinal thickness and anatomy to detect macular, optic nerve, and retinal ganglion cell damage.
Fundus photography
Fundus cameras visualize the back of the eye including the retina, macula, and optic disc. Photographs document optic nerve swelling, cupping, or atrophy and retinal lesions contributing to field loss.
Fluorescein angiography
This technique uses a dye injected into the bloodstream to light up retinal blood vessels. It reveals areas of capillary non-perfusion indicating retinal ischemia. Angiography also highlights abnormalities like microaneurysms and leakage from damaged vessels.
Neuroimaging
CT scans and MRI of the brain can detect tumors, strokes, trauma, and other lesions affecting the visual cortex and pathways. Neuroimaging correlates the location of brain abnormalities with visual field deficits.
Treatment Options
Treatment focuses on halting progression of vision loss and preserving remaining sight. Options depend on the underlying cause:
Medical management
– Vascular risk factor modification – Strict control of diabetes and hypertension reduces risk of further retinal ischemia.
– Intraocular pressure lowering – Essential for preventing glaucomatous optic nerve damage.
– Corticosteroids – May reduce inflammation from autoimmune optic neuropathies.
Surgery
– Stroke, tumors, aneurysms – Neurosurgical removal or vascular repair can prevent extension of brain lesions.
– Cataract surgery – Clearing cloudy lenses improves vision in areas not affected by field defects.
– Retinal detachment repair – Fixes curtain-like loss from retinal detachment.
Low vision rehabilitation
– Eccentric viewing training – Teaches patients to aim fixation towards the blind side to place images onto functioning retina.
– Prisms – Can shift images from non-seeing areas onto intact visual field.
– Magnification devices – Optical and electronic magnifiers help make the most of remaining vision.
Prognosis
The prognosis depends on the specific cause:
– Vascular lesions – Little recovery expected. Further vision loss preventable.
– Optic neuropathies – Some drugs slow progression, but damage is often irreversible.
– Macular conditions – Vision typically declines over time.
– Brain tumors – Prognosis related to type of tumor and treatment response.
– Strokes – Spontaneous partial recovery sometimes occurs but many deficits persist.
Regular monitoring for progression and optimizing remaining vision are key to managing all types of curtain-like field loss. Low vision rehabilitation can help patients achieve maximal independence despite partially obscured vision.
Takeaways
– Curtains in vision result from localized damage anywhere along the visual pathway. Common causes are vascular disease, optic nerve damage, macular degeneration, and brain lesions.
– Characteristics of the visual field defect provide clues about the location and nature of responsible pathology. A thorough medical history and targeted diagnostic tests further evaluate possible causes.
– Although treatment options are limited for many underlying conditions, rigorous control of associated risk factors and timely intervention for potentially reversible etiologies can prevent further vision deterioration. Proper management focuses on preservation of remaining functional vision.