The Amsler Grid chart, a commonly used method for detection of macular pathologies, has been utilized in detection of visual field (VF) defects in advanced glaucoma. [1]
However, a new card developed by Dr. Ronald
Caronia, is apparently more efficacious in detecting scotomas and readily acceptable
by patients with severe glaucoma compared to the Amsler grid. [2]
The Caronia Glaucoma Card (CGC) design
incorporates a vertical and horizontal line and seven concentric circles
corresponding to 1-degree arc at normal reading distance.
The 7 concentric circles surround a central
‘X’. The first circle surrounding the ‘X’ creates 1-degree of arc from the
center, and each of the other circles creates an additional 1-degree arc from
the previous circle.
The end result is a card which evaluates 7
degrees of peripheral field from fixation, giving the full extent of peripheral
field testing to 14 degrees.
In a study conducted by Dr. Caronia, the
patients were given a card on which the Amsler grid was printed on one side and
the CGC on the other. The patients were asked to use either one or both tests
to monitor their visual function on a weekly basis. Upon return, they were
asked which test they preferred and if they appreciated or noticed any change
in their scotoma.
The study reported that 30 patients out of 67 preferred the CGC (60%), while 8
patients preferred the Amsler grid (16%) for monitoring their VFs. Twelve patients found no difference
between the 2 test designs (24%). [χ2 (2, 50) =16.480,
ρ=0.000]. Five patients noticed a change in their scotoma while using the card
(5.8%, 5 of 86 eyes). All were exclusively using the CGC.
The report concluded that the CGC is a convenient
and inexpensive tool to assess VF defects in glaucoma and has high acceptance
by patients to monitor their glaucoma status.
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