Iannaccone Alessandro, Kritchevsky Stephen B, Ciccarelli Maria Laura, Tedesco Salvatore A, Macaluso Claudio, Kimberling William J, Somes Grant W
Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
Invest Ophthalmol Vis Sci. 2004 Mar;45(3):784-92. doi: 10.1167/iovs.03-0906.
To characterize the kinetics of visual field decay in Usher syndrome type II.
The area of 137 Goldmann visual fields (GVFs) delimited with the I4e and V4e targets was measured in each eye of 19 patients with an established diagnosis of Usher syndrome type II, and the average interocular GVF area for each patient at each time point was calculated. The average follow-up was 5.58 years. Symptomatic disease duration was defined as years elapsed after symptoms were first noted. The data set (n = 67 for the I4e target; n = 70 for the V4e target) was analyzed with a random coefficient mixed model to identify the best-fit model describing the decay of visual field size over time. The half-life of the residual visual field area (t(0.5)) was also calculated.
The variable that best explained the decay of the GVF area was the duration of symptomatic disease. In an exponential model, the slope estimate for the natural log of the GVF area was -0.172 for the I4e target and -0.136 for the V4e target for each year of symptomatic disease. Accordingly, t(0.5) was approximately 4 years for the I4e target and 5 years for the V4e target. These estimates are very similar to those in previous studies of nonsyndromic retinitis pigmentosa (RP).
This study suggests that the kinetics of GVF decline in Usher syndrome type II are, on average, very similar to other forms of RP and that, once the disease becomes symptomatic, GVF deterioration follows stereotyped kinetics, even in patients with late-onset retinal disease.
描述II型Usher综合征视野衰退的动力学特征。
对19例已确诊为II型Usher综合征的患者的每只眼睛，测量用I4e和V4e视标界定的137个Goldmann视野（GVF）的面积，并计算每个患者在每个时间点的双眼平均GVF面积。平均随访时间为5.58年。症状性疾病持续时间定义为首次出现症状后经过的年数。使用随机系数混合模型分析数据集（I4e视标n = 67；V4e视标n = 70），以确定描述视野大小随时间衰退的最佳拟合模型。还计算了残余视野面积的半衰期（t(0.5)）。
最能解释GVF面积衰退的变量是症状性疾病的持续时间。在指数模型中，对于症状性疾病的每一年，I4e视标GVF面积自然对数的斜率估计值为-0.172，V4e视标为-0.136。因此，I4e视标的t(0.5)约为4年，V4e视标为5年。这些估计值与先前非综合征性视网膜色素变性（RP）研究中的结果非常相似。
本研究表明，II型Usher综合征中GVF下降的动力学平均而言与其他形式的RP非常相似，并且一旦疾病出现症状，即使是迟发性视网膜疾病患者，GVF恶化也遵循固定的动力学模式。
