Adjustable Suture Removal: Increasing Aqueous Flow in "Safe" Trabeculectomy.

Purpose: Aqueous flow through trabeculectomy blebs has been suggested to influence filtration bleb survival. We investigated the relationship between the requirement to increase aqueous flow via adjustable suture removal and surgical outcomes following "safe trabeculectomy" with mitomycin C (MMC). Methods: 62 consecutive eyes of 53 patients underwent fornix based trabeculectomy with adjustable sutures, intraoperative MMC and intensive postoperative steroids. Subconjunctival antimetabolite injections and bleb needlings were administered according to bleb vascularity and IOP trends. Main outcome measures were: success rates (definition: IOP≤21mmHg and 20% IOP reduction); number of antimetabolite injections; bleb needlings; number of of eyes recommencing glaucoma medications and complications. Results: Mean age was 70.4±16.0 years (mean± SD); mean preoperative IOP was 24.5±9.1 mmHg and decreased to 12.3±8.9mmHg postoperatively. Mean number of sutures was 2.6 ± 0.7. Eyes were divided into 2 groups in relation to the number of sutures removed. The number of subconjunctival MMC injections required for those requiring 2 suture removals was significantly greater than those requiring 1 suture removal (p<0.05) The number of needlings and 5FU injections also increased but did not reach significance (p=0.09 and p=0.34 respectively). Least-squared linear regression analysis showed the number of needlings required had a statistically significant (p=0.05) trend with respect to time elapsed between surgery and first suture removal. No other interventions had significant trends. Mean time between surgery and suture removal was: 4.2±9.2 weeks (suture #1) and 5.7±9.7 weeks (suture#2). Antiglaucoma medication was restarted in only 5 eyes. Postoperative complications were infrequent: Seidel (3.2%), peripheral choroidal effusions at any time (3.2%), and shallow anterior chamber (1.6%). Conclusion: Eyes requiring a greater number of suture removals required a significantly greater number of antifibrosis interventions. The time elapsed before suture removal was inversely related to the number of postoperative needlings, suggesting these eyes may have decreased aqueous production and therefore require aggressive post-operative management to prevent bleb failure.

The co-evolution of culturally inherited altruistic helping and cultural transmission under random group formation.

Limited migration results in kin selective pressure on helping behaviors under a wide range of ecological, demographic and life-history situations. However, such genetically determined altruistic helping can evolve only when migration is not too strong and group size is not too large. Cultural inheritance of helping behaviors may allow altruistic helping to evolve in groups of larger size because cultural transmission has the potential to markedly decrease the variance within groups and augment the variance between groups. Here, we study the co-evolution of culturally inherited altruistic helping behaviors and two alternative cultural transmission rules for such behaviors. We find that conformist transmission, where individuals within groups tend to copy prevalent cultural variants (e.g., beliefs or values), has a strong adverse effect on the evolution of culturally inherited helping traits. This finding is at variance with the commonly held view that conformist transmission is a crucial factor favoring the evolution of altruistic helping in humans. By contrast, we find that under one-to-many transmission, where individuals within groups tend to copy a "leader" (or teacher), altruistic helping can evolve in groups of any size, although the cultural transmission rule itself hitchhikes rather weakly with a selected helping trait. Our results suggest that culturally determined helping behaviors are more likely to be driven by "leaders" than by popularity, but the emergence and stability of the cultural transmission rules themselves should be driven by some extrinsic factors.