astigmatism
Let an agent explain astigmatism in general terms, relay types, causes, measurement and correction options from optometry and ophthalmology sources, route sudden vision changes to eye care, describe the named types, and distinguish astigmatism from myopia, hyperopia, presbyopia, keratoconus as a disease and optical astigmatism in lenses.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify
Researched by: Claude
Purpose and description
Let an agent explain astigmatism in general terms, relay types, causes, measurement and correction options from optometry and ophthalmology sources, route sudden vision changes to eye care, describe the named types, and distinguish astigmatism from myopia, hyperopia, presbyopia, keratoconus as a disease and optical astigmatism in lenses.
A common refractive error in which the cornea or lens is unevenly curved, so light focuses at different points in different meridians, causing blurred or distorted vision at all distances, eyestrain and headaches, classified as regular astigmatism, where principal meridians are perpendicular and correctable with cylindrical lenses, and irregular astigmatism, often from keratoconus, scarring or surgery, which may need rigid contact lenses or other treatment; it is measured in dioptres of cylinder at an axis in eye tests and can be corrected with glasses, contact lenses or refractive surgery. Sudden changes in vision need prompt eye care.
What it is for: Not applicable; a refractive error.
It can be explain types and causes; relay measurement; relay correction options in general terms; route sudden vision changes.
Distinguishing features
Meridian-dependent focus
Blur at all distances
Correctable
Regular and irregular forms
What it looks like
Not visible externally; shown in prescriptions as cylinder and axis values.
Physical character
prescription notation: cylinder in dioptres and axis in degrees note
first described in eyes: Thomas Young, 1801 note
regular correction: toric or cylindrical lenses note
How it is recognised
Refractive error from uneven curvature
Regular astigmatism, irregular astigmatism
Myopia is short-sightedness; hyperopia is long-sightedness; presbyopia is age-related focusing loss; keratoconus is corneal thinning; lens astigmatism is an optical aberration
Related models
is a kind of - related
is corrected by -
can be caused by - irregular
is contrasted with -
In practice
Families and kinds
corneal astigmatism
lenticular astigmatism
with-the-rule and against-the-rule astigmatism
irregular astigmatism
Standards and regulation
Optometric practice standards
Refractive surgery regulations
Contact lens prescription laws
Failure modes and hazards
Missing sudden vision changes
Unsafe contact lens use
Giving individual prescriptions
Also called
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.astigmatism
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.
Understand What astigmatism is.
Science.
Definition
Definition.
Definition
Definition.
- Is there sudden vision loss, flashes, a curtain over vision or eye pain, in which case seek urgent eye care? boundary
- What is astigmatism, and how does it differ from myopia, hyperopia, presbyopia, keratoconus and lens aberration? definition
Types
Named types.
Types
Types.
- What are regular and irregular astigmatism? definition
- Which entry fits the specific type? action
Optics Optics.
Science.
Meridians
Meridians and focus.
Meridians
Meridians.
- Why does uneven curvature focus light at different points? provenance
- Which references are standard? provenance
Prescription
Reading a prescription.
Prescription
Prescription.
- What do sphere, cylinder and axis mean on a prescription? measurement
- Which sources are cited? provenance
Correction Correction.
Regulation.
Lenses
Glasses and contacts.
Lenses
Lenses.
- How do toric lenses and rigid contact lenses correct astigmatism? provenance
- Which entry fits contact lens? action
Surgery
Refractive surgery.
Surgery
Surgery.
- What surgical options exist, and what risks do regulators note, in general terms? provenance
- Which entry fits LASIK? action
Context Children and history.
Context.
Children
Children s vision.
Children
Children.
- Why is untreated astigmatism in children linked to amblyopia? provenance
- Which entry fits amblyopia? action
History
Thomas Young.
History
History.
- How did Thomas Young and George Airy describe and correct astigmatism? provenance
- Is the information current? boundary
What the second pass must settle
- Should irregular astigmatism be a separate entry?
- How should optometry guidelines be linked?
- Should the registry parent referring to itself be corrected?