Article Text

Download PDFPDF
Retinal nerve fibre layer thickness associates with phenylketonuria control and cognition
  1. Jan Krzysztof Nowak1,
  2. Łukasz Kałużny1,
  3. Wojciech Suda2,
  4. Anna Bukowska-Posadzy1,3,
  5. Alex Adams4,
  6. Ireneusz Grulkowski5,
  7. Jarosław Kocięcki2,
  8. Jarosław Walkowiak1
  1. 1 Department of Pediatric Gastroenterology and Metabolic Diseases, Poznan University of Medical Sciences, Poznan, Poland
  2. 2 Department of Ophthalmology, Poznan University of Medical Sciences, Poznan, Wielkopolskie, Poland
  3. 3 Department of Clinical Psychology, Poznan University of Medical Sciences, Poznan, Wielkopolskie, Poland
  4. 4 Translational Gastroenterology Unit, Nuffield Department of Clinical Medicine, Division of Experimental Medicine, University of Oxford, Oxford, Oxfordshire, UK
  5. 5 Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Torun, Poland
  1. Correspondence to Dr Jan Krzysztof Nowak, Department of Pediatric Gastroenterology and Metabolic Diseases, Poznan University of Medical Sciences, 61-701 Poznan, Poland; jan.nowak{at}

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

Phenylketonuria (PKU) is efficaciously treated by low-phenylalanine (Phe) diet but the views on the acceptable range of Phe constantly evolve. In 1997, German guidelines allowed Phe concentrations of up to 20 mg/dL (1200 µmol/L) in adults.1 Currently, American and European recommendations are discordant, promoting Phe levels below 6 and 10 mg/dL (360 and 600 µmol/L) from adolescence onwards, respectively.2 3 There are insufficient data to prefer one over the other recommendation, which reduces patient motivation, and the objective tools to resolve the dispute or elucidate unexplored vulnerability factors are scarce.4 5 An easily interpretable, accessible and non-invasive biomarker of neural damage in PKU is lacking. We demonstrate that retinal nerve fibre layer (RNFL) thickness measured using optical coherence tomography (OCT) may associate with PKU control and cognition.

This observational study enrolled 15 patients with classical PKU diagnosed through newborn screening and aged 15.2±5.2 years (mean±SD; 5 men and 10 women). All patients gave informed written consent for their participation in the study. All the participants underwent a standard eye examination, which was unremarkable, followed by retinal OCT scanning (DRI OCT Triton, Topcon, Tokyo, Japan). The peripapillary RNFL thickness in four sectors (nasal, inferior, temporal and superior) was extracted from the acquired three-dimensional OCT datasets using built-in software of the instrument. Psychological assessment was conducted using the Wechsler Adult Intelligence Scale or the revised Wechsler Intelligence Scale for Children by one practitioner (ABP) who has been providing care to the …

View Full Text