Visual recognition time in strabismus: small-angle versus large-angle deviation.

PURPOSE: To measure the possible differences in monocular detection time of a threshold visual acuity stimulus (recognition time [RT]) between patients with small-angle and large-angle strabismus. METHODS: Ten patients with free alternating esotropia were tested (10 to 18 years old): five with small-angle esotropia (< or = 7 degrees), five with large-angle esotropia (15 degrees to 20 degrees). Six age-matched normal subjects served as controls. The RT of the threshold stimulus was measured in both eyes sequentially for stimuli presented in the center of a computer monitor (RT 1). Moreover, we measured the time necessary for identifying the same threshold visual acuity stimulus generated on the computer screen in the moment in which fixation is taken up by one eye after occlusion of the second eye (RT 2). Using the same setting, RT was also measured monocularly in all strabismic and normal subjects who were originally looking at a luminous fixation point positioned horizontally at 6.5 and 15 degrees from the center of the monitor (RT 3). RESULTS: The multivariate analysis of variance for repeated measures indicated that there was no statistical difference in RT 1 between groups. The mean RT 2 was significantly longer (p<0.001) in large-angle strabismic eyes when compared with that of normal control eyes. The mean RT 2 in small-angle strabismic eyes did not differ significantly from that of normal eyes. Finally, RT 3 (both at 6.5 degrees and 15 degrees of eccentricity) did not show any significant difference in the three different study groups. CONCLUSIONS: The authors hypothesized that alternating strabismus patients may have a significant advantage in maintaining a small-angle deviation, as a large-angle deviation would require longer RT in the moment the deviated eye takes up fixation. It can be speculated that the extension of re-fixation movement, obviously shorter in small-angle strabismus patients, is the main factor responsible for longer RT occurring in large-angle strabismus patients.

[Lipids in enteral nutrition: does an optimal ratio between omega-6 and omega-3 exist?]. / I lipidi in nutrizione enterale: esiste un rapporto ottimale omega-6/omega-3?

The ratio between PUFA omega-6 and omega-3 is 3:1 in the unweaned, 5:1 in the young man, 5-10:1 in the adult. The PUFA omega-6 prevail over omega-3 because of elongation and desaturation processes. Linoleic acid is the beginning of the omega-6 series, a-linolenic acid of the omega-3 series. Both acids give rise to PUFA which must be introduced with diet because the human race is not able to synthetize. They represent the 2-6% of total daily caloric intake and correspond about to 10 g every day according to LARN 1986-1987. During some diseases (after surgery, trauma, sepsis, etc.) their need increases until 25-50 g every day, so it is necessary a proper enteral nutrition (EN). For this reason the bromatological composition of diets for EN must respect the physiological ratio between omega-6 and omega-3 PUFA. The composition of 37 diets for EN was examined and it was found that 7 (18%) have a proper ratio between the two series of PUFA. Twenty-three (62%) do not signal any ratio, two have 6:1, two 4.5:1, in three the ratio is in favour of omega-3. Then the concentration of linoleic and alfa-linolenic acid was examined and it was found that 24 (64%) diets signal the concentration of linoleic acid, 10 (27%) of both acids, two have no data about and only one diet reports the concentration of alfa-linolenic acid. A more exact formulation of PUFA into the composition of EN diets is suggested because PUFA are now recognized to play an important role in the fields of inflammation and immunity.