We numerically investigate the fluid dynamics of the infusion of balanced salt solution into the vitreous chamber during ophthalmic surgery. A 25-gauge vitrectomy set consisting of an infusion cannula and a vitreous cutter is inserted in a realistic model of a human vitreous chamber. As the vitreous cutter aspirates at a constant flow rate (7.5–20 ml min−1 in the present study), the corresponding infusion flow generates a high-velocity laminar jet (1.00–2.65 m s−1) causing high stress on the retina (pressure up to 1200 Pa) and mixing. We analyse the Lagrangian coherent structures and quantify mixing. Results show a vortex ring around the jet impingement region, in the posterior part of the chamber. At higher infusion rates (Re > 600), interacting hairpin vortices emerge as a result of an instability in the vortex ring. This disordered flow enhances mixing, potentially dispersing substances such as vital dyes, with consequences on visibility and surgery time. We quantify the overall mixing and its evolution with height, observing a smooth transition from an ordered flow to an unsteady disordered one with the flow rate. These findings may pave the way towards strategies to minimise complications while optimising efficiency, especially given the trend towards minimally invasive surgery with progressively smaller infusion cannulas.

The aim of this study was to examine the pattern of comorbidity among obsessive-compulsive personality disorder (OCPD) and other personality disorders (PDs) in a sample of 400 psychiatric inpatients. PDs were assessed using the Semistructured Clinical Interview for DSM-III-R Personality Disorders (SCID-II). Odds ratios (ORs) were calculated to determine significant comorbidity among OCPD and other axis II disorders. The most elevated odds ratios were found for the cooccurrence of OCPD with cluster A PDs (the “odd” PDs, or paranoid and schizoid PDs). These results are consistent with those of previous studies showing a higher cooccurrence of OCPD with cluster A than with cluster C (“anxious”) PDs. In light of these observations, issues associated with the nosologic status of OCPD within the Diagnostic and Statistical Manual of Mental Disorders clustering system remain unsettled.

Objective - The aim of this study was to asses type and prevalence of Personality Disorders (PDs) and their patterns of comorbidity with Axis I disorders in a sample of psychiatric inpatients. Setting - The sample consisted of 300 subjects admitted to a psychiatric unit on a voluntary bases for an index episode. The study was conducted over a period of 12 months, from 1.11.1997 to 31.10.1998. Main outcome measures - The Italian version of SCID-II-PQ (Structured Clinical Interview for DSM-III-R personality disorders, with Personality Questionnaire-PQ- a self report questionnaire). Results - More than half the patients had at least one personality disorder. The mean of disorders per patient was 2.83±1.93 (±SD). The most prevalent Axis II disorders were Borderline PD (30.7%), Obsessive-compulsive PD (30.7%) and Avoidant PD (25.3%). Women were significantly more likely than men to meet criteria for Dependent PD and Avoidant PD. Man showed significantly more frequently than women Antisocial PD. Significant associations (p<0.05) were found for comorbidity of Mood Disorders and Avoidant PD, and for Psicoactive Use Disorders and Antisocial PD. Conclusions - Our study confirms the high prevalence of PDs in psychiatric inpatients and showes some interesting associations between Axis I and Axis II disorders. These results can't be generalized to outpatients because our clinical sample involved mainly severely ill inpatients, but they raise questions about the exact nature of PDs and of the relationship with Axis I disorders. Further research involving outpatients and general population is needed to examine factors that could affect development and course of Personality Disorders.

Objective - The aim of this study was to verify the construct validity of the Italian version of Parental Bonding Instrument (PBI) a questionnaire which estimates the parental style as reported by the son or daughter. Method - The questionnaire was administered to a group of 102 students (62 males and 40 females) attending University of L'Aquila and to a sample of 128 patients (76 males and 52 females) consecutively admitted to a psychiatric unit for an index episode. We compared the means of the two factors (care, protection) separately for each parent in the two groups using a t-test for indipendent samples. After having estimated the internal consistency of items of each scale by calculating Cronbach's coefficient α, a factor analysis was performed for students and patients to find the structural factors of the questionnaire; then, we conducted a confirmatory factor analysis of the PBI items, for the students only, to evaluate the fit of the real items to models proposed in the literature. Results - The Italian version of the Parental Bonding Instrument, demonstrated the ability to discriminate between patients and controls; it showed an high internal consistency. The factor analysis identified a two factors solution which accounted for 44.6% and 44.3% of the variance of the mother's and father's PBI scores respectively for the group of students and it identified two factors which accounted for 49.3% and 46.6% of the variance in the group of patients. Conclusions - The psychiatric patients showed a low «care»-high «protection » confirming an association between the «affectionless control» pattern and psychiatric disorders.