Villaseñor-Schwarz JH, Villaseñor-Rodríguez C

Language: Spanish
References: 16
Page: 55-60
PDF size: 553.12 Kb.

ABSTRACT

Objective: Analysis of mechanical changes shown by scleral tissue due to the forces induced by placement of the 240 silicone band as an eyeball alignment constituent in relation to some inconsistent post surgical results of the procedure.
Methods: Mechanical analysis of a mathematical model by use of MATLAB version 6.5 software in three stages: 1. Finite Element Analysis of the 240 silicone band, 2. Scleral tissue modeling and analysis of its dynamical response to band placement, 3. Simulation of scleral tissue behavior in response to external forces by means of suture insertion point modeling.
Results: First analysis: Force distribution along the band finds a maximum value at its ends. Second analysis: Scleral tissue will be torn when the steady-state deformation value is achieved. Third analysis: There is a balance between the suture depth and applied band force.
Conclusions: The mechanical changes revealed by the mathematical analysis of the three stipulated concepts show scenarios and conditions that are previously and partially understood: force interaction exerted by the new location of the lateral rectus and the band placed in its new position spawn scleral surface alterations that participate to some extent in the final result. The band acts as an inelastic element due to minimal deformation and maximum resistance shown. The elastic action of the band over scleral tissue displays a cutting effect, freeing it from the system, thus making the procedure fail. A different force distribution should be applied to achieve better results.

REFERENCES

1. Von Noorden GK. Binocular vision and ocular motility. St Louis, The CV Mosby Co, 1980. 478.

2. Knapp P. Simposium on Strabismus. St. Louis: The CV Mosby Co, 1978.350-2.

3. Helveston EM. Atlas of Strabismus Surgery. St. Louis, The CV Mosby Co, 1977. 156-9.

4. Dyer JA. Atlas of extraocular muscle surgery. Philadelphia, WB Saunders Company, 1970. 156.

5. Knapp P. Symposium on horizontal ocular deviations. St. Louis, The CV Mosby Co, 1971. 161.

6. Hugonier R. Strabismus, heterophoria, ocular motor paralysis. St. Louis, The CV Mosby Co, 1969. 659.

7. Bedrossian H. The Surgical and nosurgical management of strabismus. Springfield, Charles C Thomas Publisher, 1969.178.

8. Folk E. Treatment of strabismus. Springfield, Charles C Thomas Publisher, 1965. 26-7.

9. Villaseñor JH: Tratamiento quirúrgico actual de la parálisis del tercer par. An Soc Mex Oftalmol 1984, (58):13-32.

10. Salazar J. Surgical correction of paralytical strabismus utilizing fascia lata. J Pediatr Ophthalmol Strabismus 1998.

11. Salazar J. Tratamiento quirúrgico con fascia lata de los estrabismos paralíticos. Actualidades del Estrabismo Latinoamericano. Consejo Latinoamericano de Estrabismo. Ciba Vision 1998, 469-479.

12. Bicas HEA: Posibilidad de sustitución artificial de la fuerza muscular en casos de parálisis oculomotora. Actualidades del Estrabismo Latinoamericano. Consejo Latinoamericano de Estrabismo. CibaVision 1998, 313–330.

13. Bicas HEA. A surgical implanted elastic band to restore paralysed ocular rotations. J Ped Ophthalmol Strab1991; 28: 10–13.

14. Arroyo ME, Fonte A. Cirugía dinámica del estrabismo. Inutilidad de la medición milimétrica en la cirugía del estrabismo. Temas Selectos de Estrabismo. Centro Mexicano de Estrabismo. 1993, 143–148.

15. Logan DL. A first course in the finite element method. Brooks Cole, tercera edición. 2001, 110-250.

16. Askeland DR. Ciencía e ingeniería de materiales. Brooks Cole, tercera edición. 2000, 123-269.