The use of hyaluronic acid during adjustable suture surgery

Comparison of the Effectiveness of Mitomycin-C and Viscoat on Delayed Adjustable Strabismus Surgery in Rabbits

Purpose

To determine a way to prevent the formation of adhesions and delay the time of suture adjustment in the course of adjustable strabismus surgery, an animal study was performed to assess and compare the effects of mitomycin C (Mit-C) and viscoelastic material Viscoat (sodium hyaluronate 3% and chondroitin sulphate 4%, Alcon, Fort Worth, TX).

Methods

Right eyes of 47 rabbits were divided into three groups. After recession of the superior rectus muscle (SRM), Mit-C was administered beneath and over the SRM in Group M (16 eyes), Viscoat was administered beneath and over SRM in Group V (16 eyes), and ringer lactate was administered in Group C (15 eyes). SRM then recessed 5 mm with adjustable strabismus surgery technique. Animals in each group were subdivided into 1 and 2, where 1 = adjustment 1 week postoperatively and 2 = adjustment 3 weeks postoperatively. Delayed adjustment was performed in M1 group (6 eyes), V1 group (6 eyes), and C1 group (7 eyes) after 1 week; in M2 group (6 eyes), V2 group (6 eyes), and C2 group (6 eyes) after 3 weeks. Histopathologic examinations were performed for the remaining 10 eyes without suture adjustment at the end of first and third weeks after adjustable strabismus surgery. The possible length and the necessary force to adjust and the degree of adhesions were recorded.

Results

When length and strength of the adjustment, adhesions between muscle and sclera, and adhesions between muscle and conjunctiva were taken into consideration, there was no statistically significant difference among M, V, and C groups at postoperative weeks 1 and 3. The force needed for adjustment in M1 group was statistically lower than M2 group.

Conclusions

The intraoperative use of Mit-C (0.4 mg/mL) may decrease adhesion formation in the early postoperative period, especially in the first week. The intraoperative use of Viscoat was not effective in reducing postoperative adhesions and delaying adjustment.

Slipping the knot: a comparison of knots used in adjustable suture strabismus surgery

PURPOSE

To evaluate the frictional force created by different knots used in adjustable suture strabismus surgery.

METHODS

To allow the simulation of strabismus surgery suture tying methods a model using 6-0 polyglactin 910 suture was created. Three different knots were evaluated: (1) the sliding noose knot with a double wrap of suture, (2) the cinch knot with a single throw on both sides of the pole suture, (2) and a single-throw square knot. (Bow-tie knots were not included.) A digital force meter was used to measure the force (gram-force [gf]) required to overcome the static friction created by the knot. Each simulation was repeated with new suture material 5 times and the force required after subsequent repositioning was also recorded.

RESULTS

The force to overcome static friction of the sliding noose knot was 240 gf [95% CI, 187-284 gf]; of the cinch knot, 150 gf [95% CI, 123-167 gf]; and of the square knot, 110 gf [95% CI, 95-121 gf]. Subsequent movement of each knot along the same suture required progressively less force, with the sliding noose maintaining the most static friction.

CONCLUSIONS

The sliding noose knot generates the most frictional force and also maintains the most friction after subsequent repositioning. Important consideration should be given to multiple repositioning movements, because the force required for each subsequent repositioning decreases.

Combined effect of polytetrafluoroethylene and 5-fluorouracil on delayed adjustable strabismus surgery

PURPOSE

To determine a more reliable method for performing delayed suture adjustment to prevent the formation of postoperative adhesions and delay the time of adjustment.

METHODS

Thirty-two rabbit eyes were divided into three groups. After recession of the superior rectus muscle, 5-fluorouracil (5-FU) was administered beneath and over the superior rectus muscle in group 5-FU (12 eyes); polytetrafluoroethylene (PTFE) and 5-FU were administered in group P-f (10 eyes); and PTFE, 5-FU, and Viscoat (chondroitin sulfate, sodium hyaluronate, Alcon Laboratories Inc, Fort Worth, Tex) were administered in group P-fv (10 eyes). Delayed adjustment was performed once on each superior rectus muscle at 1, 2, and 3 weeks postoperatively in group 5-FU and at 2 and 4 weeks postoperatively in groups P-f and P-fv. The length and force for the adjustment and the degree of adhesions were recorded.

RESULTS

The use of fluorouracil allowed adjustment to be delayed up to 1 week after surgery in three of four eyes. The combined use of PTFE and 5-FU or addition of Viscoat allowed adjustment to be delayed for up to 4 weeks after surgery in four of five eyes.

CONCLUSION

The combined use of PTFE, 5-FU and Viscoat is useful for delaying suture adjustment in rabbit eyes.

Clinical characteristics of surgically treated adult strabismus

BACKGROUND

Strabismus is present in approximately 4% of the population with most forms becoming clinically evident in infancy and childhood. Adult strabismus, including that resulting from recurrent childhood deviations, varies in etiology, presentation, symptomatology, and response to treatment. This report is intended to prospectively characterize adults who required surgical correction of their strabismic deviation.

METHODS

Beginning in 1991, a prospective computerized database was collected that contained all clinical, laboratory, and surgical information on the adult ocular motility service at the Scheie Eye Institute and The Children's Hospital of Philadelphia (Philadelphia, Pa). Analysis of those patients who underwent surgical correction of their strabismus is included in this report. Demography, clinical characteristics, and surgical procedures including results were analyzed separately in adults with their strabismus beginning before visual maturation (BVM) (9 years of age) and after visual maturation (AVM).

RESULTS

A minimum of 6 months and average of 1.8 years follow up is reported on 262 procedures in 255 patients with an average age of 37 between January 1991 and January 1996. Sixty-two percent of patients had their strabismus onset BVM. Fifty-one percent of BVM patients and 80% of AVM patients had incomitant deviations. Adjustable suture surgery was performed on 97% of all patients, with 28% of BVM and 57% of AVM patients having multiplanar surgery. Successful motor alignment was achieved in 85% of all patients after one surgical procedure. Sensory success was achieved in 81% of all AVM patients and 25% of all BVM patients. Subjective success was 94% in both groups of patients.

CONCLUSIONS

Numerous differences exist between childhood and adult strabismus characteristics and response to surgery. Although strabismus surgery is effective, differences in results reflect the varied physiology regarding etiology, pathophysiology, and symptomology. Classification into AVM and BVM groups will provide continued clarity for future studies.