Astigmatism

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Last reviewed: 29 Apr 2025

Last updated: 21 Sep 2023

Astigmatism is a refractive error characterized by a variation in the dioptric power of the eye from one meridian to another.

The most common symptom is diminished visual acuity.

The etiology is still unknown, but it is probably influenced by both genetic and environmental factors.

Among the common risk factors are a family history of astigmatism; myopia; Native American, East Asian, Hispanic, or Brazilian ethnic origin; eye trauma or surgery; and certain genetic and eyelid pathologies.

In most cases, the diagnosis is clinical and further diagnostic tests are usually not necessary.

Screening in the pediatric population is essential, primarily to decrease the risk of amblyopia.

Definition

Astigmatism is a refractive error characterized by a variation in the dioptric power of the eye from one meridian to another, rendering the optical system incapable of generating a clear image.[1] Instead of having a spherical cross-section, the cornea and/or lens is cylindrical, with different focal power depending on the plane in which the light travels (the meridian). The meridians that have the greatest and the least dioptric power are known as the principal meridians.

Total refractive astigmatism can be divided into corneal (most cases), lenticular, and retinal.[1] Regular corneal astigmatism occurs when the principal meridians are at 90° to each other; irregular corneal astigmatism refers to cases where the magnitude and the axis of astigmatism varies at different points of the cornea. Lenticular astigmatism is a result of uneven lens curvature, lens tilt, and differing refractive indices within the lens.

History and exam

Key diagnostic factors

blurred vision

Full details

Other diagnostic factors

asthenopia (eye strain)
distorted retinal reflex
Munson sign

Full details

Risk factors

positive family history
presence of myopia
Native American, African-American, East Asian, Hispanic, or indigenous Brazilian ethnicity
eye trauma or surgery
genetic syndromes
eyelid pathology

Full details

Diagnostic tests

1st tests to order

retinoscopy

Full details

Tests to consider

keratometry
corneal topography
wavefront analysis technology
anterior-segment optical coherence tomography (AS-OCT)

Full details

Treatment algorithm

ACUTE

borderline astigmatism in patients ages ≥1 year

regular astigmatism

irregular astigmatism

Contributors

Authors

Erez Bakshi, MD

Department of Ophthalmology

Assaf Harofeh Medical Center

Tel Aviv University

Israel

Disclosures

EB declares that he has no competing interests.

David Zadok, MD

Principal Investigator

Department of Ophthalmology

Assaf Harofeh Medical Center

Tel Aviv University

Israel

Disclosures

DZ declares that he has no competing interests.

Peer reviewers

Michael P. Ehrenhaus, MD

Assistant Professor of Ophthalmology

Cornea External Disease and Refractive Surgery Local Director

Long Island College Hospital Eye Center

Brooklyn

Disclosures

MPE declares that he has no competing interests.

Gus Gazzard, MA, MBBChir, MD, FRCOphth

Consultant Ophthalmic Surgeon

King's College Hospital

Honorary Research Fellow

Institute of Ophthalmology

London

Disclosures

GG declares that he has no competing interests.

Richard Davidson, MD

Assistant Professor

Department of Ophthalmology

Rocky Mountain Lions Eye Institute

University of Colorado Denver School of Medicine

Denver

Disclosures

RD serves on the speakers bureaux for Alcan Inc and Allergan Inc. The work for these companies does not conflict with the review or nature of this topic.

Robert Chang, MD

Associate Professor of Ophthalmology

Ophthalmology Research/Clinical Trials

Stanford University

Palo Alto

Disclosures

RC declares that he has no competing interests.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Jacobs DS, Afshari NA, Bishop RJ, et al. Refractive errors preferred practice pattern®. Ophthalmology. 2023 Mar;130(3):P1-60.Full text Abstract

Read SA, Collins MJ, Carney LG. A review of astigmatism and its possible genesis. Clin Exp Optom. 2007 Jan;90(1):5-19. Abstract

Gwiazda J, Grice K, Held R, et al. Astigmatism and the development of myopia in children. Vision Res. 2000;40(8):1019-26. Abstract

Hutchinson AK, Morse CL, Hercinovic A, et al. Pediatric eye evaluations preferred practice pattern. Ophthalmology. 2023 Mar;130(3):P222-70.Full text Abstract

Jacobs DS, Lee JK, Shen TT, et al. Refractive surgery preferred practice pattern®. Ophthalmology. 2023 Mar;130(3):P61-135.Full text Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials
- Myopia
- Hyperopia
- Cataract
More Differentials
Guidelines
- Refractive surgery preferred practice pattern
- Vision rehabilitation preferred practice pattern
More Guidelines
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Astigmatism

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic tests

1st tests to order

Tests to consider

Treatment algorithm

borderline astigmatism in patients ages ≥1 year

regular astigmatism

irregular astigmatism

Contributors

Authors

Erez Bakshi, MD

Disclosures

David Zadok, MD

Disclosures

Peer reviewers

Michael P. Ehrenhaus, MD

Disclosures

Gus Gazzard, MA, MBBChir, MD, FRCOphth

Disclosures

Richard Davidson, MD

Disclosures

Robert Chang, MD

Disclosures

References

Key articles

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials

Guidelines

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice