Abstract
Purpose To evaluate the indications and results of inverse Knapp procedures performed at one institution over a 10 year period between 1987 and 1996.
Methods The records of patients who had undergone inverse Knapp procedures were retrospectively reviewed. Demographic data were collected, pre- and post-operative orthoptic assessments were evaluated, and pre-and post-operative binocular single vision (BSV) charts and Hess charts were scored.
Results Twenty-one patients were identified and records were available in 17. The main indication for the operation was orbital trauma. The mean vertical deviation in primary position and downgaze improved from 16.06 prism dioptres (PD) to 7.35 PD and 26.45 PD to 6.66 PD respectively. The pie-operative average score for BSV was 42%, increasing to 62% post-operatively. The Hess chart error scores improved on average from 848.8 pre-operatively to 296.4 post-operatively. Further operations were required for 8 patients.
Conclusions Inverse Knapp procedure is an uncommon strabismus operation but an extremely useful one in selected cases. We recommend it for the treatment of marked inferior rectus weakness, congenital or acquired, for post-traumatic inferior rectus underaction with or without orbital blow-out fracture and for residual large hypertropia in patients with poor binocular functions. The extent of inferior rectus underaction should be assessed very carefully to avoid overcorrecting.
Similar content being viewed by others
Article PDF
References
Alvaro M . Simultaneous surgical correction of vertical and horizontal strabismus. Ophthalmologica 1950;120:91–7.
Knapp P . The surgical treatment of double-elevator palsy. Trans Am Ophthalmol Soc 1969;67:304–23.
Burke JP, Ruben JB, Scott WE . Vertical transposition of the horizontal recti (Knapp procedure) for the treatment of double elevator palsy: effectiveness and long term stability. Br J Ophthalmol 1992;76:734–8.
Cooper EL, Greenspan JA . Congenital absence of the inferior rectus muscle. Arch Ophthalmol 1971;86:451–4.
Dunlap EA . Vertical displacement of horizontal recti. In: Symposium on strabismus. St Louis: CV Mosby, 1971:307–29.
Lipton JR, Page AB, Lee JP . Management of diplopia on down-gaze following orbital trauma. Eye 1990;4:535–7.
Burke JP, Keech RV . Effectiveness of inferior transposition of the horizontal rectus muscles for acquired inferior rectus paresis. J Pediatr Ophthalmol Strabismus 1995;32:172–7.
Denning AM, Ansons AM, Spencer AL, Kranemann C . Does the degree of inferior rectus palsy influence the effectiveness of the inverse Knapp procedure? Trans Eur Strabismus Assoc 1997;24:97–102.
von Noorden GK, Hansell RH . Clinical characteristics and treatment of isolated inferior rectus paralysis. Ophthalmology 1991;98:253–7.
Woodruff G, O'Reilly C, Kraft SP . Functional scoring of the field of binocular single vision in patients with diplopia. Ophthalmology 1987;94:1554–61.
Aylward GW, McCarry B, Kousoulides L, Lee JP, Fells P . A scoring method for Hess charts. Eye 1992;6:659–61.
Metz HS . Saccades with limited downward gaze. Arch Ophthalmol 1980;98:2204–5.
Lee JP . Modern management of sixth nerve palsy. Aust NZ J Ophthalmol 1992;20:41–6.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Maurino, V., Kwan, A. & Lee, J. Review of the inverse Knapp procedure: Indications, effectiveness and results. Eye 15, 7–11 (2001). https://doi.org/10.1038/eye.2001.4
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/eye.2001.4
Keywords
This article is cited by
-
Inverse Knapp procedure
Eye (2001)