Clinical Optometry Practice: Aberrometry
Wavefront Aberrometry
features procedure notes
What is it 1. Patient rests the chin on the Produces a topographic image of
chin rest and the distorted wavefront
• Objective method of measuring 2. looks at the instrument - spot of
refractive power light Uses
• Offers detailed measurements of 3. Light passes through the pupil 1. Used to design very accurate
the movement of the light and is reflected back by the correction lenses or to guide
wavefront cornea refractive surgery
4. Wavefront of reflected beam is 2. This enables the detection and
Can be used in the diagnosis of both compared to that of the treatment of conditions that
higher order and lower order refractive reference wavefront impair vision at each stage of
errors 5. Points of variation are recorded light passage through the eye
and measured, creating an 3. Aids to understand how
• Higher order errors refer to optical fingerprint contact lenses actually affect
conditions that include complex the whole optic system of the
visual defects: coma, trefoil eye
• Lower order errors:
nearsightedness, farsightedness Ways to analyze the findings
and astigmatism 1. Outgoing wavefront
aberrometer
Useful as a guide in making of 2. ingoing retinal imaging
spectacles and contact lenses to offer aberrometer
sharper and clearer vision 3. ingoing feedback aberrometer
4. Technique will change the
Light is thought of as being a traveling speed at which the results are
wave available, the range of
refractive error, and the
• Shape of the wave reflects the potential to analyze and
movement of individual light measure different aberrations
photons 5. Better to combine the methods
with medical imaging or with
• As it passes through the normal
topographic maps
eye, the front of the wave
(wavefront) presents a flat shape,
while irregularities represents
defects in vision
Intraoperative measures for cataract surgery
features
Optiwave Refractive Analysis (ORA) system
Reduces guesswork
• Aberrometer helps minimize the astigmatism
Detects posterior astigmatism
• Posterior astigmatism can cause unanticipated refractive error after cataract surgery
Helps with picky patients
• Predictability of refractive outcomes is important especially to those patients paying a high price for IOLs
• Presbyopic or toric IOLs
Fewer enhancements needed
Enhancement rates fell by nearly half according to some studies
Device drawbacks
Long learning curve
Readings difficult in some eyes
• ORA has difficulty capturing data from highly aberrated corneas (penetrating keratoplasty or radial
keratotomy)
Added time
• 15-30 seconds to 5-6 minutes added to surgical time
Wavefront aberrometry & CL
Features notes
Can aid in detecting and managing many corneal Careful analysis can be useful in obtaining a detailed
conditions as well as in evaluating patients for soft analysis of the optical pathway from the pre-corneal
multifocal CL tear film to the vitreous humor and the retina
Analyze the findings produced by optical systems using Allows clinicians to detect, diagnose and treat
three distinct methods divided into three classifications: conditions that have optical consequences in an effort to
• Outgoing wavefront aberrometers reduce optical consequences
• Ingoing retinal imaging aberrometers
• Ingoing feedback aberrometers Can help clinicians better understand CL and specialty
• Differ based on CL interactions with the entire optical system, not just
1. Measurement speed the corneal surface
2. Refractive error range
3. Analysis and display options Most common HOAs (Higher order aberrations)
4. Ability to measure different aberrations o Coma
o Spherical aberration
• All are more successful and provide more
information when combined with other technologies Diseases or conditions that affect the optical
o Topography components
o Medical imaging • Ectasia can cause HOAs
1. Trefoil
Multifocal Fits 2. Tetrafoil
• Success of soft multifocal CLs depends on the 3. Secondary astigmatism
alignment of the multifocal optics with visual axis • Located on the front or back surface of the cornea
• Cataracts can be accompanied by high levels of
trefoil due to internal optics of the lens
• Misalignment alters the way patients perceive visual
clues and may occur for several reasons Combining aberrometry with corneal topography and
o Scleral or corneal misshape pupillometry
o Nasal decentration of the pupil • Allows assessment of the physiological alignment
o Temporally displaced foveas of the optical structures in the eye
• Significant misalignment may result in • Locate HOAs and lower order aberrations in the
o Reduced VA optical pathway
o Induced aberrations • Analyze the effects of pupil size
o Patient complaints of glare, shadows, 3D effects • Affects the angular aperture of light entering the
and halos posterior part of the eye
Large angles kappa or alpha can present challenges
Angle Kappa when fitting patients with multifocal intraocular lenses
• Angle between the visual axis and the
pupillary axis Combining corneal topo and wavefront aberrometry
allows these devices to evaluate the distance between
Angle Alpha the pupillary center and the visual axis
• Angle between the optical axis and the center of the
cornea CLs are usually centered or nearly centered on the
cornea
• The closer the center of a lens is to the optical axis,
the more symmetric the combined power
distribution is around the optical axis
• The further the center of a lens from the optical axis,
the more asymmetric the combined power
distribution
o Creates HOAs and results in negative visual
symptoms
