Purpose

Retinal changes are poorly described in early treated phenylketonuria (ETPKU). We aimed to investigate possible visual functional and ocular microstructural changes in adult patients with ETPKU. Optical coherence tomography (OCT) and its angiography (OCTA) data from patients with PKU were compared to healthy controls.

Methods

In this prospective, monocentric, cross-sectional, case-control study 50 patients with ETPKU and 50 healthy subjects were evaluated with OCT and OCTA. Measurements were performed on right eyes. The following visual function parameters were studied: best corrected visual acuity (BCVA), spherical equivalent (SE), contrast sensitivity and near stereoacuity; microstructural parameters: retinal nerve fiber layer thickness (RNFLT), ganglion cell layer (GCC) thickness, focal loss of volume (FLV), global loss of volume (GLV), peripapillary, papillary vessel density (VD), ocular axial length (AL) and intraocular pressure (IOP).

Results

Among functional tests there were significant differences in contrast sensitivity at 1.5 (p < 0.001), 6 (p < 0.013), 12 (p < 0.001), 18 (p < 0.003) cycles per degree, in near stereoacuity (Titmus Wirt circles, p < 0.001) and in best corrected visual acuity (BCVA, p < 0.001). A statistically significant, moderate positive linear correlation was observed between BCVA and average Phe levels over the last ten years (β = 0.49, p < 0.001). The average (p < 0.001), superior (p < 0.001) inferior GCC (p < 0.001), the FLV (p < 0.003), GLV (p < 0.001) and the average RNFLT (p < 0.004) values of the PKU group were significantly lower than the controls. The serum phenylalanine level (Phe) in the PKU group negatively correlated with inferior (−0.32, p < 0.007), superior (r = −0.26, p < 0.028) and average (−0.29 p < 0.014) RNFL and with AL (−0.32, p < 0.026). In AL we detected a significant difference (p < 0.04) between the good and suboptimal dietary controlled group. There was no significant difference between the ETPKU and control group in the measured vessel density parameters and in IOP.

Conclusions

Our results suggest that functional and ocular microstructural defects are present in patients with PKU, and some of them may depend on dietary control. The mechanism is unclear, but the correlation indicates the importance of strict dietary control in terms of preservation of retinal functions.

中文翻译：

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早期治疗成人 PKU 患者的视觉功能、黄斑神经节细胞和乳头状视网膜神经纤维层厚度改变

目的

在早期治疗的苯丙酮尿​​症 (ETPKU) 中对视网膜变化的描述很少。我们旨在调查成人 ETPKU 患者可能的视觉功能和眼部微结构变化。将来自 PKU 患者的光学相干断层扫描 (OCT) 及其血管造影 (OCTA) 数据与健康对照进行比较。

方法

在这项前瞻性、单中心、横断面、病例对照研究中，50 名 ETPKU 患者和 50 名健康受试者接受了 OCT 和 OCTA 评估。在右眼上进行测量。研究了以下视觉功能参数：最佳矫正视力（BCVA）、等效球镜（SE）、对比敏感度和近立体视力；显微结构参数：视网膜神经纤维层厚度 (RNFLT)、神经节细胞层 (GCC)厚度、局部体积损失 (FLV)、整体体积损失 (GLV)、视乳头周围、乳头血管密度 (VD)、眼轴长度 (AL ) 和眼压 (IOP)。

结果

在功能测试中，每度 1.5 ( p  < 0.001)、6 ( p  < 0.013)、12 (p < 0.001)、18 ( p  < 0.003) 周期的对比敏感度存在显着差异，接近立体视度 (Titmus Wirt circles, p  < 0.001) 和最佳矫正视力 (BCVA, p < 0.001)。在过去十年中观察到 BCVA 和平均 Phe 水平之间存在统计学上显着的中度正线性相关性（β = 0.49，p  < 0.001）。平均 (p < 0.001)、优越 (p < 0.001) 劣质 GCC (p < 0.001)、FLV ( p  < 0.003)、GLV (p < 0.001) 和平均 RNFLT ( p < 0.004) PKU 组的值显着低于对照组。PKU 组的血清苯丙氨酸水平 (Phe) 与劣质 (-0.32, p  < 0.007)、优质 (r  =  -0.26, p  <  0.028)和平均 (-0.29 p  < 0.014) RNFL 和 AL (- 0.32，p  < 0.026）。在 AL 中，我们检测到良好和次优饮食对照组之间的显着差异 ( p  < 0.04)。在测量的血管密度参数和眼压方面，ETPKU 和对照组之间没有显着差异。

结论

我们的研究结果表明，PKU 患者存在功能和眼部微结构缺陷，其中一些可能取决于饮食控制。其机制尚不清楚，但相关性表明严格饮食控制在保护视网膜功能方面的重要性。