Ultimate tensile strength of gamma irradiated human scleral sutures.

Scleral sutures were prepared by hand from the equatorial region of 53 paired donor eyes. The weakening produced by two doses of gamma Co-60 radiation (2.7 and 4.0 Mrads) was compared using measurements of tensile strength; the strength of unirradiated scleral sutures was also measured, for comparison. The three variables of tensile strength, viz. Breaking Elongation, Breaking Load, and Work of Rupture was determined for each suture. As compared to unirradiated sutures, Breaking Elongation decreased on irradiation (P less than 0.01), but the two doses of irradiation were not statistically significant (P greater than 0.05); Breaking Load increased on irradiation (P less than 0.01), but the two doses of irradiation were again not significant (P greater than 0.05). Only 4.0 Mrads irradiated scleral sutures, as compared to unirradiated ones, showed a statistically significant reduction (P less than 0.01) for Work of Rupture. No definite relationships were found by regression analysis among the tensile strength variables and the independent variables of sex and various storage times for the 4.0 Mrad data. Work of Rupture showed a negative relationship to the age of donors, though the change with age was small.