Tamanho do estímulo de fixação e resposta acomodativa para longe

Size of stimulus of fixation and far accommodative response

RESUMO

A resposta acomodativa de 23 indivíduos normais foi medida com o auto-refrator Canon R-1® para longe (4 metros) durante a fixação de optotipos de dois tamanhos diferentes (20/30 e 20/100). Houve uma hiperacomodação média de 0.24 D na fixação dos optotipos de menor valor angular. As diferenças de acomodação para longe não foram correlacionadas à acomodação tônica medida no escuro e foi sugerido que o efeito da percepção de tamanho possa estar relacionado ao esforço mental (atenção).

Palavras-chave:
acomodação; optotipos; esforço mental

SUMMARY

The far focus of 23 normal subjects was measured, at 4 meters, with the Canon R-1®. Optotypes with two different sizes (20/30 and 20/100) were used as fixation stimuli. With the 20/100 optotypes the mean accommodative response was equal to the distance requirement (0.25D) . With the 20/30 optotypes there was an accommodative lead of 0.24D . The differences in far focus were not correlated with the magnitude of darkfocus. The effect of optotype size on accommodation may be similar to the effect of mental activity.

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• Trabalho realizado no Department of Brain and Cognitive Sciences, Infant Vision Laboratory, Massachusetts Institute of Technology, Cambridge, USA.

REFERÊNCIAS BIBLIOGRÁFICAS

• ¹
  BULLIMORE, M.A.; GILMARTIN, B.; HOGAN, R.E. - Objective and subjective measurement of tonic accommodation. Ophthalmic Physiol. Opt. 6: 57-62, 1986.
• ²
  CHARMAN, W.N. & TUCKER, J. - Dependence of accommodation response on the spatial frequency spectrum of the observed object. Vision Res. 17: 129-39, 1977.
• ³
  CIUFFREDA, K.J.; DUL, M.; FISHER, S.K. - High-order spatial frequency contribution to accommodative accuracy in normal and amblyopic observers. Clin. Vision Sci. 1: 219-29, 1987.
• ⁴
  HEATH, G.G. - Components of accommodation. Am. J. Optom. Arch. Am. Acad. Optom. 33: 569-79, 1956.
• ⁵
  HENNESSY, R.T. & LEIBOWITZ, H. - Subjective measurement of accommodation with laser light. J. Opt. Soc. Am 60: 1700-1, 1970.
• ⁶
  HURTT, J.; RASICOVICI, A.; WINDSOR, C.E. - Comprehensive review of orthoptics and ocular motility. Saint Louis: C.V. Mosby Comp., 1972, p. 125.
• ⁷
  LEIBOWITZ, H.W. & OWENS, D.A. - Anomalous myopias and the intermediated dark focus of accommodation. Science 189: 646-8, 1975.
• ⁸
  _____ ______ Night myopia and the intermediate dark focus of accommodation. J. Opt. Soc. Am 65: 1121-8, 1975.
• ⁹
  _____ ______ New evidence for the intermediate position of relaxed accommodation. Doc. Ophthalmol. 46: 133-47, 1978.
• ¹⁰
  LOVASIK, J.V.; KERGOAT, H.; KOTHE, A.C. - The influence of letter size on the focusing response of the eye. J. Am. Optom. Ass. 58: 631-9, 1987.
• ¹¹
  MCBRIEN, N.A. & MILLODOT, M. - The relationship between tonic accommodation and refractive error. Invest. Ophthalmol. Vis. Sci. 28: 997-1004, 1987.
• ¹²
  MEIN, J. & HARCOURT, B. - Diagnosis and Management of ocular motility disorders. Oxford: Blackwell, 1986, p. 100.
• ¹³
  ROSENFELD, M. - Evaluation of clinical techniques to measure tonic accommodation. Optom. Vis. Sci. 66: 809-14, 1989.
• ¹⁴
  ROSENFELD, M. & CIUFFREDA, K.J. - Effect of surround propinquity on the open-loop accommodative response. Invest. Ophthalmol. Vis. Sci. 32: 142-7, 1990.
• ¹⁵
  TAN, R.K.T. & O'LEARY,D.J. - Steady-state accommodation response to different Snellen letter sizes. Am. J. Optom. Physiol. Opt 62: 751-4, 1985.
• ¹⁶
  TOATES, F.M. - Accommodation function of the human eye. Physiol. Rev. 52: 828-63, 1972.
• ¹⁷
  WARD, P.A. & CHARMAN, W.N. - An objective assessement of the effect of fogging on accommodation. Am. J. Optom. Physiol. Opt 64: 762-7, 1987.
• ¹⁸
  WINN, B.; GILMARTIN, B.; MORTIMER, L.C.; EDWARDS, N.R - The effect of mental effort on open- and closed-loop accommodation. Ophthalmic Physiol. Opt 11: 335-9, 1991.

Datas de Publicação

• Publicação nesta coleção
  Apr 1993