Unique characteristics of two types of retinitis pigmentosa patients with different rod sensitivities.
OBJECTIVE
To determine the psychophysical differences between two types of retinitis pigmentosa (RP) patients with different rod sensitivities.


METHODS
Thirty-five RP patients with a visual acuity of > or =0.7 or better were classified by cone-rod perimetry into type 1, those with undetectable rod sensitivity, and type 2, those with measurable rod sensitivity. Their symptoms, age at onset of symptoms, cone and rod sensitivity, and full-field electroretinograms (ERGs) were compared.


RESULTS
The age when the symptoms of night blindness were first noticed was 13.1 +/- 3.3 years (mean +/- SD) for type 1 and 34.5 +/- 14.4 years for type 2 patients (P = 0.0001). One of nine type 1 patients (11%) and 10 of 26 type 2 patients (38%) did not have any symptoms of night blindness. The average rod sensitivity within the central 10 degrees was 43.7 +/- 12.0 dB for type 2 patients with night blindness, and 54.8 +/- 6.4 dB for type 2 patients without night blindness (P = 0.014). One of nine (11%) type 1 patients and 9 of 23 (39%) type 2 patients had recordable ERGs (P = 0.13).


CONCLUSIONS
These findings indicate that the two types of RP patients, distinguished by their rod sensitivity, have different psychophysical characteristics of the visual system. The course of the disease process and the long-term prognosis for these two types of patients are different.
Takahashi
Hiroaki
H
Nagaya Eye Clinic, Aichi, Japan. tak8@se.starcat.ne.jp
Miyake
Yozo
Y
Horiguchi
Masayuki
M
Tomida
Naoki
N
Takakuwa
Hideo
H
D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D002648:Child; D003623:Dark Adaptation; D004596:Electroretinography; D006801:Humans; D008875:Middle Aged; D009755:Night Blindness / Q000503:physiopathology; D017949:Retinal Cone Photoreceptor Cells / Q000503:physiopathology; D017948:Retinal Rod Photoreceptor Cells / Q000503:physiopathology*; D012174:Retinitis Pigmentosa / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology*; D012684:Sensory Thresholds; D014792:Visual Acuity; D058609:Visual Field Tests