Neuroretinal dysfunction in patients affected by neurofibromatosis type 1

AIM:To examine neuroretinal function by using the multifocal electroretinography(mf ERG)test in patients with neurofibromatosis type 1(NF1)without optic pathway gliomas(OPGs).METHODS:This study was conducted on 35 patients(35 eyes)with NF1 and 30 healthy subjects(30 eyes)for the control group.Each subject underwent a complete ophthalmological examination including spectral domainoptical coherence tomography(SD-OCT)and mf ERG.The 1.5-Tesla magnetic resonance imaging(MRI)scan of the brain was performed in NF1 patients to assess the presence of OPGs.All participants were recruited having a best corrected visual acuity(BCVA)of no less than 20/20 in each eye.The amplitude and implicit time of the P1 wave(first-order Kernel component)were evaluated on mf ERG.Data analysis was carried out in the two central degrees and in the four quadrants from two to 25 degrees of visual field.RESULTS:Statistically significant results were obtained for the P1 wave amplitudes in the 4 quadrants in NF1 patients compared to healthy controls,while the reduction was not significant in the 2 central degrees between the groups.A statistically significant difference was observed among the P1 wave amplitudes as recorded in the 4 quadrants within the NF1 group,with lower amplitudes detected in the nasal quadrants.No differences in the implicit times were recorded in the 2 central degrees and in the 4 quadrants as compared between NF1 patients and controls.CONCLUSION:Impaired neuroretinal function in NF1 patients is expressed in a decreased amplitude of the P1-wave between 2 and 25 central retinal degrees on mf ERG.Altered intracellular signal transduction due to abnormal neurofibromin-mediated cyclic adenosine monophosphate(c AMP)generation,can be involved.The possible use of mf ERG as subclinical retinal damage indicator has a potential utility in clinical practice for the follow-up of NF1 patients.

A virtual model of the retina based on histological data as a tool for evaluation of the visual fields

Background:To settle the fundamentals of a numerical procedure that relates retinal ganglion-cell density and threshold sensitivity in the visual field.The sensitivity of a generated retina and visual pathways to virtual stimuli are simulated,and the conditions required to reproduce glaucoma-type defects both in the optic-nerve head(ONH)and visual fields are explored.Methods:A definition of selected structural elements of the optic pathways is a requisite to a translation of clinical knowledge to computer programs for visual field exploration.The program is able to generate a database of normalized visual fields.The relationship between the number of extant receptive fields and threshold sensitivity is plotted for background sensitivity and corresponding automated perimetry.A solution in two planes to the 3D distribution of axons in the ONH is proposed.Visual fields with induced damage in the optic disc are comparable in pattern and quantity to glaucomatous records.Results:The two-level simulation of the ONH facilitates the analysis of optic-cup/retinal defects.We can generate the virtual optic pathways tailored to the age and morphology of the patient’s eye,and it is possible to reproduce glaucomatous damage by“reverse engineering”engineering.The virtual cortical model renders a quantitative relationship between visual defect and neural damage.Conclusions:A two-level computing of the retina/optic nerve facilitates the analysis of neuroretinal defects and can be incorporated to automatic perimeters to facilitate visual field analysis.

Pediatric neuro-ophthalmology:not simply neuro-ophthalmology for small adults

Pediatric neuro-ophthalmology is a subspecialty within neuro-ophthalmology.Pediatric neuro-ophthalmic diseases must be considered separate from their adult counterparts,due to the distinctive nature of the examination,clinical presentations,and management choices.This manuscript will highlight four common pediatric neuro-ophthalmic disorders by describing common clinical presentations,recommended management,and highlighting recent developments.Diseases discussed include pediatric idiopathic intracranial hypertension(IIH),pseudopapilledema,optic neuritis(ON)and optic pathway gliomas(OPG).The demographics,diagnosis and management of common pediatric neuro-ophthalmic disease require a working knowledge of the current research presented herein.Special attention should be placed on the differences between pediatric and adult entities such that children can be appropriately diagnosed and treated.