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ULY CLINIC

ULY CLINIC

17 Septemba 2025, 12:04:45

Scotoma

Scotoma
Scotoma
Scotoma

A scotoma is an area of partial or complete blindness within an otherwise normal or slightly impaired visual field. Typically located within the central 30 degrees, the defect ranges from absolute blindness to a barely detectable loss of visual acuity. Patients can often pinpoint the scotoma’s location in their visual field. Scotomas may result from retinal, choroidal, or optic nerve disorders.


Types of scotomas:

  • Absolute scotoma: total inability to see test objects

  • Relative scotoma: can see only larger objects

  • Scintillating scotoma: flashes or bursts of light, often associated with migraines


Pathophysiology

Scotomas arise from localized dysfunction of the visual pathway, including:

  • Retinal disorders: degeneration or inflammation of photoreceptors

  • Choroidal disorders: chorioretinitis causing local ischemia or hemorrhage

  • Optic nerve pathology: demyelination, inflammation, or compression

  • Macular involvement: central vision loss due to foveal damage

These abnormalities lead to reduced signal transmission to the brain, resulting in areas of visual field loss.


History and Physical Examination

History should include:

  • Onset, duration, and progression of visual defect

  • Laterality (unilateral or bilateral)

  • Associated symptoms: blurred vision, photophobia, pain, color changes

  • History of eye disorders, systemic diseases, or migraines

  • Medication use or exposure to ocular toxins


Physical examination:

  • Visual acuity testing

  • Pupil assessment: size, equality, reaction to light

  • Ophthalmoscopic examination: assess retina, macula, optic nerve

  • Intraocular pressure measurement

  • Visual field testing:

    • Tangent screen

    • Goldmann perimeter

    • Automated perimetry

    • Confrontation testing

    • Amsler grid (especially for foveal/macular evaluation)

Medical Causes

Cause

Laterality

Onset

Key Features

Ophthalmoscopic / Clinical Findings

Pathophysiology

Management

Chorioretinitis

Usually unilateral

Acute or subacute

Scotoma, blurred vision, photophobia

Clouding in vitreous, subretinal hemorrhage, neovascularization

Inflammation of choroid and retina

Treat underlying infection/inflammation, corticosteroids if indicated

Macular degeneration

Usually bilateral

Gradual

Central scotoma, distortion, reduced color perception

Changes in macular area, drusen

Degenerative process affecting fovea centralis

Monitor with Amsler grid, anti-VEGF therapy, low vision aids

Optic neuritis

Usually unilateral

Acute

Central or centrocecal scotoma, pain with eye movement, vision loss

Optic disc hyperemia, blurred margins, retinal vein distention

Inflammation/demyelination of optic nerve

Corticosteroids, treat underlying cause, monitor visual recovery

Retinal pigmentary degeneration (e.g., retinitis pigmentosa)

Usually bilateral

Insidious, progressive

Peripheral vision loss → tunnel vision, night blindness

Narrowed retinal vessels, optic disk pallor

Photoreceptor degeneration, rod-cone loss

Low vision rehabilitation, genetic counseling, supportive care


Locating ccotomas

Scotomas are classified by visual field location: central, paracentral, centrocecal, peripheral, or annular. Normal physiologic scotoma exists in the temporal region. Tools for localization: Amsler grid, perimetry tests.


Special Considerations

  • Teach patients with foveal involvement to use the Amsler grid to detect progression of macular degeneration.

  • Educate about progression, complications, and assistive devices (magnifiers, electronic aids).

  • Emphasize the need for regular eye examinations.


Patient counseling

  • Explain disease progression and potential complications

  • Demonstrate use of visual aids and rehabilitation devices

  • Advise reporting new visual changes immediately

  • Emphasize adherence to follow-up and treatment plans


Pediatric considerations

  • Visual field testing in young children is challenging; requires patience

  • Confrontation visual field testing is the preferred method

  • Monitor closely for progressive visual loss in congenital or hereditary conditions


References

  1. Biswas J, Krishnakumar S, Ahuja S. Manual of Ocular Pathology. New Delhi, India: Jaypee–Highlights Medical Publishers; 2010.

  2. Gerstenblith AT, Rabinowitz MP. The Wills Eye Manual. Philadelphia, PA: Lippincott Williams & Wilkins; 2012.

  3. Levin LA, Albert DM. Ocular Disease: Mechanisms and Management. London, UK: Saunders Elsevier; 2010.

  4. Roy FH. Ocular Differential Diagnosis. Clayton, Panama: Jaypee–Highlights Medical Publishers; 2012.

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