Birch D G, Anderson J L, Fish G E
Retina Foundation of the Southwest, Dallas, Texas 75231, USA.
Ophthalmology. 1999 Feb;106(2):258-68. doi: 10.1016/S0161-6420(99)90064-7.
To provide the first measures of the relative rates of rod and cone functional loss in patients with retinitis pigmentosa (RP) or cone-rod dystrophy (CRD).
Five-year, prospective natural history study.
Ninety-six patients (67 with RP and 29 with CRD) retaining measurable rod-mediated visual function and 5 normal subjects were tested at baseline and annually for 4 consecutive years.
Tests of visual function included visual acuity, dark-adaptation thresholds, dark-adapted static perimetry, and rod and cone computer-averaged electroretinograms (ERGs), which were obtained over a range of retinal illuminances. Intervisit variability for each measure was obtained in a subset of patients who were tested twice within a 2-month interval and was used to determine whether an individual patient had shown progression, regression, or no change over a particular study interval.
Over a 4-year interval, a significant number of patients with RP (60%) and CRD (62%) showed a decline in cone ERG amplitude. For rod ERG amplitude, the percentage of patients with RP or CRD showing progression was 64% and 45%, respectively. Although visual acuity, dark-adapted threshold, and rod visual field area also declined significantly over the 4-year period, the mean rate of change and the numbers of patients showing progression on these measures were lower than those for ERG measures. On specialized ERG testing, the yearly change in rod ERG threshold in RP was greater than the yearly change in cone ERG threshold, and the rate of progression varied significantly among inheritance types. For patients with CRD, the yearly change in rod threshold was comparable to the yearly change in cone ERG threshold.
This study helps to define the natural progression of rod-mediated and cone-mediated functional loss in patients with RP and CRD.
提供视网膜色素变性（RP）或视锥 - 视杆营养不良（CRD）患者视杆和视锥功能丧失相对速率的首批测量数据。
为期五年的前瞻性自然病史研究。
96名患者（67例RP患者和29例CRD患者）保留可测量的视杆介导视觉功能，以及5名正常受试者，在基线时进行测试，并连续4年每年测试一次。
视觉功能测试包括视力、暗适应阈值、暗适应静态视野检查，以及在一系列视网膜照度下获得的视杆和视锥计算机平均视网膜电图（ERG）。在2个月内接受两次测试的部分患者中获得每项测量的访间变异性，并用于确定个体患者在特定研究间隔内是否出现进展、消退或无变化。
在4年期间，大量RP患者（60%）和CRD患者（62%）视锥ERG振幅下降。对于视杆ERG振幅，显示进展的RP或CRD患者百分比分别为64%和45%。尽管在4年期间视力、暗适应阈值和视杆视野面积也显著下降，但这些测量指标的平均变化率和显示进展的患者数量低于ERG测量指标。在专门的ERG测试中，RP患者视杆ERG阈值的年变化大于视锥ERG阈值的年变化，并且进展速率在遗传类型之间有显著差异。对于CRD患者，视杆阈值的年变化与视锥ERG阈值的年变化相当。
本研究有助于明确RP和CRD患者视杆介导和视锥介导功能丧失的自然进展。
