[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Ophthalmology](https://durgical.com/en/ophthalmology/) › [The eye exam](https://durgical.com/en/ophthalmology/areas/exam/) › Contrast sensitivity and glare testing # Contrast sensitivity and glare testing - Examination Some people read the chart well but see poorly in fog, at dusk or into headlights. Contrast and glare tests measure this everyday vision. Updated Nov 13, 2026 **See it in 3D:** [Lens](https://durgical.com/en/anatomy/lens/) · [Macula](https://durgical.com/en/anatomy/macula/) · [Optic nerve](https://durgical.com/en/anatomy/optic-nerve/) ## Key points - Snellen = high contrast only. - Pelli-Robson: same size, fading contrast. - Cataract (posterior subcapsular): glare out of proportion to acuity. - Optic neuritis: contrast loss persists. - Poor contrast: falls and night-driving trouble. ## What it is Contrast sensitivity is the ability to see objects that differ only slightly from their background, such as a kerb at dusk or a face in shadow. The Snellen chart uses black letters on white and misses this loss. Letter charts that fade in contrast at a fixed size (Pelli-Robson) and grating charts across several stripe widths measure it. Glare testing repeats acuity or contrast with a bright light shining towards the eye and shows how much scattered light, as from a cataract, degrades vision. ## Normal values and scales - Young adults score close to the top of the Pelli-Robson scale; scores fall with age, and a clear drop below age norms is a real deficit. - Posterior subcapsular cataract and capsule opacification cause much more glare disability than chart acuity suggests. - Contrast falls early in optic neuritis, glaucoma, diabetic retinopathy and macular degeneration, even with 6/6 acuity. - After refractive surgery, some patients notice halos, night glare and reduced contrast. - Low contrast sensitivity in older people is linked to falls and to difficulty driving. ## How it is done - Test with the patient's usual glasses, in standard room lighting, one eye at a time. - Pelli-Robson chart: the patient reads groups of three letters that become fainter; the score is the faintest group read with at least two letters right. - Grating charts: the patient reports the direction of stripes of different widths; the results form a contrast sensitivity curve. - Glare: repeat acuity or contrast while a bright light source is directed towards the eye at set levels. - Compare with the other eye and with normal values for age. ## How to interpret it - A patient with good chart acuity but disabling glare, trouble driving at night or in sunlight may still benefit from cataract surgery. - In optic neuritis, contrast often stays reduced after acuity has recovered. - Good lighting, high-contrast markings at home and anti-glare measures help patients whose deficit cannot be corrected. ## Next step / Initial management - Good acuity but disabling glare or night-driving problems: refer to ophthalmology; glare testing can support cataract surgery or capsulotomy. - Glare and halos after refractive surgery: refer back to the surgeon. - Reduced contrast with normal acuity and fundus: think of the optic nerve; check pupils for a relative afferent defect and colour vision. - Older adult with falls and poor contrast: improve lighting and contrast at home, check glasses and consider low-vision referral. ## Test yourself Think of the answer, then tap the question to see it. ## How does the Pelli-Robson chart differ from a Snellen chart? Its letters keep the same size and become fainter, so it measures contrast rather than resolution. ## A patient reads 6/9 but cannot drive into oncoming headlights. Which type of cataract is typical? Posterior subcapsular cataract, which causes glare out of proportion to acuity. ## Which optic nerve disease often leaves reduced contrast sensitivity after acuity recovers? Optic neuritis. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/ophthalmology/contrast-sensitivity-and-glare-testing/) ## Connections ## See it in 3D 3 The structures of Durgical's 3D anatomy where it is found. - [Lens](https://durgical.com/en/anatomy/lens/) - [Macula](https://durgical.com/en/anatomy/macula/) - [Optic nerve](https://durgical.com/en/anatomy/optic-nerve/) ## Related 5 - [Visual acuity: Snellen, logMAR and pinhole](https://durgical.com/en/ophthalmology/visual-acuity-snellen-logmar-and-pinhole/) - [Colour vision testing](https://durgical.com/en/ophthalmology/colour-vision-testing/) - [After cataract surgery: the complications the general doctor sees](https://durgical.com/en/ophthalmology/after-cataract-surgery-the-complications-the-general-doctor-sees/) - [Low vision and visual rehabilitation](https://durgical.com/en/ophthalmology/low-vision-and-visual-rehabilitation/) - [Refractive surgery: what the general doctor should know](https://durgical.com/en/ophthalmology/refractive-surgery-what-the-general-doctor-should-know/) ## Related conditions 5 - [Cataract](https://durgical.com/en/conditions/cataract/) - [Optic neuritis](https://durgical.com/en/conditions/optic-neuritis/) - [Open-angle glaucoma](https://durgical.com/en/conditions/open-angle-glaucoma/) - [Age-related macular degeneration](https://durgical.com/en/conditions/age-related-macular-degeneration/) - [Diabetic retinopathy](https://durgical.com/en/conditions/diabetic-retinopathy/) [← All of ophthalmology](https://durgical.com/en/ophthalmology/) Educational content; not a clinical guideline and no substitute for assessment by a health professional. For sudden visual loss, severe eye pain, a chemical burn or an eye injury, go to an emergency department at once. Sources: [Contrast Sensitivity](https://www.ncbi.nlm.nih.gov/books/NBK580542/) (StatPearls Publishing (NCBI Bookshelf), 2023); [Cataract](https://www.ncbi.nlm.nih.gov/books/NBK539699/) (StatPearls Publishing (NCBI Bookshelf), 2024). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/ophthalmology/contrast-sensitivity-and-glare-testing/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/ophthalmology/contrast-sensitivity-and-glare-testing/