Brightness Acuity Meter (BAM) Glare Test
● Identifies and Quantifies Glare Disability
● Document the glare disability in your record
● Open the Option for Early
Surgical Intervention and Quality of Life Improvement
When the Government Comes Knocking on Your Door:
Preventative measures (such as, glare testing) can help reduce the
likelihood of a government investigation into your cataract practice.
The government demands that the health care community — including physicians
— is held accountable to assure that appropriate services are provided and
appropriate claims for payment are made.
(March 10, 2010)
BCVA of 20/50 without glare and
20/40 when glare is key. Medicare policy states that cataract
surgery is appropriate when: ”BCVA is worse than 20/50 OR 20/40
or worse with glare present”. Regional guidelines vary,
check with your local provider.
See OM Article
Brightness Acuity Meter (BAM) Triple Function Glare Tester
3. Entopic Phenomenon (Flying Corpuscles)
Brightness Acuity Meter (BAM), 3 brightness settings,
weighs only 6 ounces.
Illumination sources can
adversely reduce visual acuity by degrading image resolution
when light scattering eye conditions exist. The effect of glare
on visual acuity is measured with the BAM™.
or graded contrast images may be used as test targets.
Standard lighting brightness of the test targets is
recommended (85 cd/m2).
The BAM™ brightness and acuity
levels can be tailored to meet the needs of the examiner.
Several brightness levels can be tested or testing can be
limited to one brightness.
Conditions where glare
adversely affects acuity:
opacities or corneal edema
◘ Cataract, particularly posterior sub-capsular opacities
◘ Clouding of the posterior lens capsule
◘ Opacities in the vitreous
◘ Scratched or dirty glasses or contact lenses
BAM is primarily a
glare tester, however, due to the lighting parameters,
entoptic phenomenon of flying corpuscles can be tested.
The diffuse lighting
for the BAM is similar in principle to the
hand-held Brightness Acuity Test (BAT)1
MARCO Ophthalmic, Inc..
The BAM provides an
alternative to the BAT for those clinicians
accustomed to diffuse background glare testing.
Like the BAT, the BAM has three levels of
background illumination in a hemispheric bowl that is
held close to the eye.
As a result, one possible source of error is
pupil constriction by the illuminator; certain patients
with cataract perform better with pupil constriction,
thereby giving a false-negative test2.
Conversely, the third level (brightest) is
dazzling, inducing false-positive results2
Holliday, Trujillo, & Ruiz. Brightness Acuity
Meter (BAT) and outdoor visual acuity in cataract
patients. J Cataract and Refractive Surgery, Jan 1987,
Atlas of Cataract Surgery, Chap. 1, p2 by Samuel
PHOTOSTRESS TESTS (BAM)
brightness of the BAM provides for macular photostress testing when brightness is set on
the bowl port is occluded. The BAM™ serves as
saturating light source.
After light exposure of the macula there
is a normal delay period for visual recovery.
In certain diseases2 of
the macula the refractory period is prolonged.
Blocking the optical portal of the glare
bowl changes the glare bowl into a photostress
Entoptic Flying Corpuscles Phenomenon (BAM)
The blue-field entoptic phenomenon can be seen best by having the subject
look into light with a narrow optical
spectrum centered at a wavelength of 430
nm. Under such conditions, bright
corpuscles are observed flying around
the subject’s fovea. Most likely, this
phenomenon is caused by the fact that
red, but not white, blood cells absorb
Leukocyte movement underlies the
blue-field entoptic phenomenon3.
This entoptic phenomenon has been
shown to predict macular function in
eyes with vitreous hemorrhage4 and
The LED bulb of the BAM™ has a peak near 440 nm and
explains the prominence of this
viewing the BAM™.