Purpose: To screen for retinal ganglion cell RGC dysfunction in patients with disk abnormalities and

1
NEARLY 50 OF GLAUCOMA SUSPECTS WITH DISK
ABNORMALITIES AND NORMAL VISUAL FIELDS HAVE
ABNORMAL FUNCTION OF RETINAL GANGLION CELLS. Lori
.M Ventura MD, Richard K Parrish MD, Vittorio
Porciatti DSc. Bascom Palmer Eye Institute,
Miami, FL, U.S.A.
Technique
Example of responses
Summary
Inclusion criteria
Deviation (SDs) from normal age-corrected
amplitude and phase
Purpose To screen for retinal ganglion cell
(RGC) dysfunction in patients with disk
abnormalities and normal fields using an
automated version of the pattern
electroretinogram (PERGLA) to facilitate early
detection. Methods The PERGLA was recorded
simultaneously from both eyes of 214 patients
using skin electrodes on the lower eyelids, and
responses were expressed as deviations from
normal in SD units (see poster PO049 for
details). Results The PERGLA was abnormal in
30.4 of patients and the interocular asymmetry
was abnormal in 36.9. Forty-seven of patients
were abnormal for amplitude or latency or
interocular asymmetry. Conclusion RGC
dysfunction occurs in nearly 50 of glaucoma
suspects with normal fields.

•  Normal Standard White on White automated
  perimetry (Mean Deviation gt-3dB)
• Corrected visual acuity 20/20 or better
• Vertical C/D gt 0.5
• Vertical C/D ? 0.5 w/ disk abnormalities
• C/D asymmetry ? 0.2
• Optic disk notching/ hemorrhage
• Exclusion criteria.
• High myopia, macular degeneration, diabetes,
  multiple sclerosis, dense cataract.

Normal
Control
2 SD confidence box
PERG right eye
Amplitude deviation
Degree of interocular asymmetry (CV)
Phase deviation
PERG left eye
Grating 1.6 c/deg Contrast 95 Field diameter 24
deg Reversal 16.3 /s DFT analysis
Glaucoma
Suspect
Response severely abnormal in amplitude and phase
PERG right eye
Abnormal interocular asymmetry in amplitude and
phase
PERG left eye
Response abnormal in amplitude
Glaucoma suspects n 214 patients, n417 eyes
Normal controls n 70, 140 eyes
Deviation from age-corrected norms
The interocular asymmetry was greater than
normal in 32.7 of patients for amplitude and
23.3 for phase.
The PERG deviation from age-corrected norms was
larger than 2 Standard Deviations in 26.2 of
eyes for amplitude and in 20.4 of eyes for
phase (latency).
In many glaucoma suspects, the PERG amplitude and
phase (latency) were outside the normal
confidence limits. The older the subject, the
greater the number of abnormalities.
In control subjects the PERG amplitude and phase
decrease progressively with age. Age-corrected
norms are determined from regression lines (black
lines) and 95 confidence limits (red lines).
Summary of PERG abnormalities