What are Higher Order Aberrations?

Higher-order aberrations (HOAs) are optical imperfections that can occur in the human eye, causing deviations from ideal vision. In addition to the more well-known lower-order aberrations (LOAs) like nearsightedness (myopia), farsightedness (hyperopia), and astigmatism, higher-order aberrations involve more complex irregularities in the eye's optical system.

While lower-order aberrations can be corrected with glasses or contact lenses, higher-order aberrations are more challenging to correct for and require specialized equipment and materials.

Diagram showing convolved E's from Zernike modes with labels for different radial orders and modes, including astigmatism, defocus, coma, trefoil, quadrifoil, secondary astigmatism, spheric, secondary trefoil, and pentfoil.

A chart showing how different lower and higher order aberrations affect quality of vision.

Visual symptoms of HOAS

Halos: Concentric circles or rings around bright light sources, such as headlights or streetlights.

Starbursts: Radiating lines or rays extending from bright light sources.

Ghosting: Duplicated or overlapping images.

Coma: Distortion resembling a comet-shaped blur.

Double vision: Seeing two images instead of one.

Irregular astigmatism: Uneven distortion in different directions.

Three black and white abstract symbols on a white background, resembling a letter 'A', a letter 'E', and a letter 'E' in a circle.

These aberrations can result from factors such as irregularities in the corneal shape, scarring, previous eye surgeries, those with large pupils, or certain medical conditions affecting the eye such as keratoconus or other corneal dystrophies. They can also be induced by the aging process or from changes in the eye's internal structures.

Managing higher-order aberrations

Although custom scleral lenses are able to greatly improve the vision quality of an irregular cornea, there may still be HOAs that distort the vision. For those looking to improve their vision further, we use wavefront-guided technology to optimize and enhance their vision.

A close-up of a person's fingers holding a small, transparent contact lens with tiny black dots on its surface, against a plain white background.
Close-up of a human eye with wavefront guided ovitz scleral lens.

In our office, we use the Ovitz aberrometer to measure the optical characteristics of a patient's eye, which includes both the lower-order aberrations as well as the higher order aberrations. This provides us with a detailed map of that particular eye's visual irregularities, which is then used to create a customized wavefront corrective scleral lens. This leads to enhanced visual acuity and reduced blur for patients with complex vision issues.

Two circular plots showing wavefront displacement in micrometers, with color gradients from blue to yellow indicating different displacement levels, labeled as 'Wavefront Displacement (μm)'.

Wavefront map with traditional scleral lens showing irregularity (left); Wavefront map after HOA correction with Ovitz scleral lens (right)

Bar graph comparing two measurements of the Zernike coefficient magnitude across different eye features, with green lines indicating subclinical thresholds.

Graphs showing the amount of aberration reduction before (blue) and after (orange) the Ovitz wavefront scleral lens

Screenshot of a Point Spread Function (PSF) analysis with Strehl Ratio of 0.00139 and InSR of -6.58, displaying a bright central point with surrounding diffraction pattern on a black background.
Screenshot of a Point Spread Function (PSF) analysis with Strehl Ratio of 0.0334 and InSR of -3.4, showing a central bright spot in a black background.

The point spread function of what a dot of light looks like before HOA correction (left); the point spread function after HOA correction (right) showing much less light spread

If you would like to see if you are a Wavefront scleral lens candidate or would like to have your aberrations measured, feel free to reach out to us for a consultation visit.

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