STUDIO DELLA RELAZIONE STRUTTURA-FUNZIONE IN CORSO DI PATOLOGIE MACULARI

PURPOSE: The purpose of this study is to correlate the degree of metamorphopsia to the in vivo study of the different retinal layers' involvement using the retinal map provided by the OCT cross-sectional analysis. MATERIALS AND METHODS: Cross-sectional study conducted at the Eye Clinic, University of Trieste, Italy. Patients with symptomatic metamorphopsia for idiopathic epiretinal membrane (ERM), diabetic macular edema (DME), age-related macular disease (AMD) were included in the analysis and divided into three groups according to the macular disease. Metamorphopsia degree was analyzed with a new prototype of M-Charts, which permits quantitative analysis of the symptom. Retinal layers morphology was evaluated through OCT (Heidelberg Spectralis, Heidelberg Industries, Heidelberg, Germany) imaging and a topographic reconstruction of each retinal layer’s thickness was created. To analyze the absolute data, a normative reference database for each layer was developed. For each eye the hypothetical center of mass of the primarily interested retinal layers was computed and a vector called centroid was obtained. The displacement vector centroid of each eye in the different macular disease subgroups from the reference model was analyzed. The hypotheses that the vertical component and the horizontal component are, respectively, a statistical proxy of the information provided by M-Charts analysis, in terms of the maximal score obtained by the M-Charts, along the direction detected, were tested. A logistic regression model was assessed. RESULTS: Overall 54 eyes screened, 30 eyes of 30 patients met the inclusion criteria and were included in the analysis, 10 for each macular disease’s subgroup. 18 patients were females (60%) and 12 males (40%), with a mean age of 72.1  4.6 years. Overall best corrected visual acuity was 75.8  15.3 ETDRS letters, 72.4  13.1 for the ERM group, 78.6  5.2 and 76.8  12.5 for DME and AMD groups, respectively. Baseline characteristics of the three different macular-disease related groups were similar for age and gender (ANOVA p>0.05), constituting a homogenous study population. Overall M-score was 1.1  0.4. The subgroup analysis demonstrated a mean value of 1.4  0.4 for the ERM group, 0.8  0.3 for the DME group, and 1.1  0.3 for the AMD group. In the ERM group, the vertical component of the inner nuclear layer (INL) is a significant predictor (p = 0.02) of the M-Charts maximal value. In addition, a very high significant correlation (p < 0.001) joining the information from the INL and the nerve fibers layer, according to the following linear model, was found. In the EMD group, the vertical component of the inner plexiform layer appears to be a significant predictor (p = 0.03) of the M-Charts maximal value. In AMD group, the outer nuclear layer is a predictor (p = 0.02) of the M-Chart angle by means of the horizontal displacement component. CONCLUSIONS: The analysis confirms the hypothesis of a relationship between anatomic alteration and functional impairment. In particular, the thickening, expressed by the vertical component of the centroid, in the more internal retinal layers is correlated to the grade of metamorphopsia in patients affected by ERM and DME. Indeed, these pathologies early determine a classical involvement of inner retinal layers. In addition, the results of this analysis open the possibility that, in the early stages of AMD, a link between outer layers and metamorphopsia direction could be detected.

Obiettivo del progetto di ricerca è stato quello di analizzare la relazione esistente tra struttura anatomica e funzione visiva in corso di patologie della retina. Questa tematica di ricerca nell’ambito delle neuroscienze può essere facilmente analizzata a livello oculare grazie all’introduzione di recenti tecniche di imaging, le quali permettono uno studio della superficie retinica e dei suoi diversi strati attraverso l’acquisizione di sezioni trasversali, senza ricorrere a esami di natura istologica. Il progetto di ricerca è stato finalizzato all’arruolamento di soggetti affetti da una patologia maculare monoculare o binoculare che presentino metamorfopsia come sintomo principale. Saranno inclusi pazienti con degenerazione maculare legata all’età, edema maculare diabetico o patologie dell’interfaccia retinica, quali membrana epiretinica o trazione vitreo-maculare. La scelta di includere soggetti con tali patologie è stata valutata in base al principale interessamento di diversi strati retinici. In particolare, strati retinici interni in corso di patologie dell’interfaccia vitreoretinica, strati retinici intermedi nell’edema maculare diabetico precoce, e strati retinici esterni in occhi affetti da degenerazione maculare legata all’età. Una volta individuata la presenza della metamorfopsia averne quantificato il grado el’asse mediante l’utilizzo del test prototipo M-charts, il partecipante sarà sottoposto a imaging retinico attraverso l’utilizzo di tecnica Optical Coherence Tomography al fine di valutare l’alterazione di ogni singolo strato retinico rispetto alla patologia di base e alla localizzazione spaziale della metamorfopsia. Al termine di questa analisi combinata tra lo studio della funzione retinica alterata (metamorfopsia) e la struttura anatomica patologica, è stata valutata la presenza di una correlazione tra il sintomo della metamorfopsia e i cambiamenti morfologici anatomici per ogni singolo strato retinico rilevati nei sottogruppi rispetto alle diverse patologie di base.