Effect of extraocular muscle surgery on corneal topography
S. Kwito, M. R. Sawusch, P. J. McDonnell, D. C. Gritz, H. Moreira and D. Evensen
Department of Ophthalmology, University of Southern California School of Medicine, Los Angeles.
A computerized videokeratoscopy system was used to evaluate changes in
corneal topography after muscle surgery in 36 eyes of 18 rabbits.
Topographic analysis revealed a significant flattening of the cornea in the
superior and superotemporal octants after superior rectus recession (mean
+/- SE, -1.78 +/- 0.16 diopters) compared with control eyes undergoing a
sham procedure (-0.17 +/- 0.18 D; P less than .05). Excision of all rectus
muscles caused a generalized corneal flattening (-1.42 +/- 0.13 D; P less
than .001). A computerized, finite element model of the globe, including
the rectus muscles, demonstrated corneal deformation as a result of
extraocular muscle tension; recession of an extraocular muscle in this
model caused corneal flattening in the quadrant of the recessed muscle.
These data suggest that corneal topography is affected by extraocular
muscle tension, corroborating clinical reports of refractive change after
strabismus surgery.
