Medida da resolução visual com tabelas logarítmicas de baixo contraste em diabéticos com acuidade visual igual a 1

Schelb, Clinton; Cruz, Antônio Augusto Velasco e

doi:10.5935/0004-2749.19930060

RESUMO

A sensibilidade ao contraste de 20 pacientes diabéticos com acuidade igual a 1 e 45 controles foi medida com optotipos (tabelas logarítmicas). Quatro níveis de contraste (91, 55, 29, e 5%) foram utilizados. Análise de variância multifatorial (contraste versus categoria clínica) revelou que o efeito do contraste sobre a acuidade visual foi mais acentuado nos pacientes diabéticos. Embora já em alto contraste os diabéticos tenham diferido dos controles, essa diferença foi amplificada no menor contraste estudado. Os resultados indicam que optotipos de baixo contraste podem ser úteis para a caracterização de canais de baixa freqüência espacial.

Palavras-chave:
contraste; optotipos; acuidade visual; análise de Fourier

SUMMARY

The contrast sensitivity of 20 diabetic patients with 20/20 of visual acuity and 45 controls was measured with low contrast acuity charts. Four contrast levels were used (91, 55, 29 e 5%).

Multifactorial analysis of variance (contrast vs clinical group) showed that the interaction between the mainfactors was significant. The two groups differed for high contrast optotypes but the difference was greater for low contrast. The results indicated that optotypes can be useful for characterizing low spatial frequency channels.

Texto completo disponível apenas em PDF.

AGRADECIMENTOS

Os autores agradecem ao professor Nivaldo Vieira de Souza, pela ajuda na seleção dos pacientes e ao Conselho Nacional de Pesquisa (CNPq), pelo auxílio financeiro na forma de bolsa de doutoramento (Clinton Schelb) e bolsa de pesquisa (Antônio A. V. Cruz).

REFERÊNCIAS BIBLIOGRÁFICAS

¹
BAILEY, I.L. & LOVIE, J.E. New design principles for visual acuity letter charts. Am. J. Optom. Physiol. Opt., 53: 740-5, 1976.
²
BODIS-WOLNER, I. Visual acuity and contrast sensitivity in patients with cerebral lesions. Science, 178: 769-71, 1972.
³
BROWN, B. & LOVIE-KITCHlN, J.E. High and low contrast acuity and clinical contrast sensitivity tested in a normal population. Optom. Vis. Sci., 66: 467-73, 1989.
⁴
BROWN, B. & LOVIE-KITCHIN, J.E. Reply, Optom. Vis. Sci., 67:654-6, 1990.
⁵
CAMPBELL, F.W. & ROBSON, J. Application of Fourier analysis to the visibility of gratings. J. Physiol., 197: 551-60, 1968.
⁶
De VALOIS, R.L. & De VALOIS, K. Linear systems analysis. ln: Spatial Vision. New York, Oxford University Press, 1990, p.3-22.
⁷
HYVARINEN, L.; LAURINEN, P.; ROMANO, J. Contrast sensitivity in evaluation of visual impairment due to diabetes. Acta Ophthalmologica, 61: 94-101, 1983.
⁸
SOKOL, S.; MOSKOWITZ, A.; SKARF, B.; EVANS, R.; MOLlTCH, M.; SENIOR, B. Contrast sensitivity in diabetics with and without backgroud retinopathy. Arch. Ophthalmol., 103: 51-4, 1985.
⁹
PELLI, D.G.; ROBSON, J.G.; WILKINS, A.J. The design of a new letter chart for measuring contrast sensitivity. Clin. Vis. Sci. 2: 187-99, 1988.
¹⁰
REGAN, D & NEIMA, D. Low-contrast letter charts as a test of visual functions. Ophthalmology, 90: 1192-200, 1983.
¹¹
REGAN, D. & NEIMA, D. Low contrast letter charts in early diabetic retinopathy, ocular hypertension, glaucoma and Parkinson's disease. Brit. J. Ophthalmol., 68: 885-9, 1984.
¹²
REGAN, D. Low-contrast letter charts and sinewave grating tests in ophthalmological and neurological disorders. Clin. Vis. Sci. 2: 235-50, 1988.
¹³
REGAN, D. High and low contrast acuity. Optom. Vis. Sci. 67: 650-3, 1990.
¹⁴
SAKUMA, J.T.; DA SIVA, J.A.; CRUZ, A.A.V. Measurement of visual acuity with logarithmic charts: comparison between methods of threshold estimation. Optom. Vis. Sci., 68: 666-9, 1991.
¹⁵
SHAPLEY, R.M. & ENROTH-CUGELL, C. Visual adaptation and retinal gain controls. Progress in Retinal Research, 3: 263-346, 1984.
¹⁶
TAYLOR, H.R. Applying new design principles to the construction of an illeterate E chart. Am. J. Optom. Physiol. Opt., 55: 348-51, 1978.
¹⁷
THORN, F. & SCHWARTZ, F. Effects of dioptric blur on Snellen and grating acuity. Optom. Vis. Sci., 67: 3-7, 1990.
¹⁸
WOODHOUSE, J. & BARLOW, H.B. Spatial and temporal analysis. In: Barlow, H.B. & MOLLON, J.D. The senses Cambridge, Cambridge University Press, 1987, 134 p.
¹⁹
YAMAZAKI, H.; ADACHI-USAMI, E.; CHIBA, J. Contrast thresholds of diabetic patients determined by vep and pshychophysical measurements. Acta Ophthalmologica, 60: 386-92, 1982.

Datas de Publicação

Publicação nesta coleção
Jan-Feb 1993

Este é um artigo publicado em acesso aberto (Open Access) sob a licença Creative Commons Attribution, que permite uso, distribuição e reprodução em qualquer meio, sem restrições desde que o trabalho original seja corretamente citado.

[1] ¹
BAILEY, I.L. & LOVIE, J.E. New design principles for visual acuity letter charts. Am. J. Optom. Physiol. Opt., 53: 740-5, 1976.

[2] ²
BODIS-WOLNER, I. Visual acuity and contrast sensitivity in patients with cerebral lesions. Science, 178: 769-71, 1972.

[3] ³
BROWN, B. & LOVIE-KITCHlN, J.E. High and low contrast acuity and clinical contrast sensitivity tested in a normal population. Optom. Vis. Sci., 66: 467-73, 1989.

[4] ⁴
BROWN, B. & LOVIE-KITCHIN, J.E. Reply, Optom. Vis. Sci., 67:654-6, 1990.

[5] ⁵
CAMPBELL, F.W. & ROBSON, J. Application of Fourier analysis to the visibility of gratings. J. Physiol., 197: 551-60, 1968.

[6] ⁶
De VALOIS, R.L. & De VALOIS, K. Linear systems analysis. ln: Spatial Vision. New York, Oxford University Press, 1990, p.3-22.

[7] ⁷
HYVARINEN, L.; LAURINEN, P.; ROMANO, J. Contrast sensitivity in evaluation of visual impairment due to diabetes. Acta Ophthalmologica, 61: 94-101, 1983.

[8] ⁸
SOKOL, S.; MOSKOWITZ, A.; SKARF, B.; EVANS, R.; MOLlTCH, M.; SENIOR, B. Contrast sensitivity in diabetics with and without backgroud retinopathy. Arch. Ophthalmol., 103: 51-4, 1985.

[9] ⁹
PELLI, D.G.; ROBSON, J.G.; WILKINS, A.J. The design of a new letter chart for measuring contrast sensitivity. Clin. Vis. Sci. 2: 187-99, 1988.

[10] ¹⁰
REGAN, D & NEIMA, D. Low-contrast letter charts as a test of visual functions. Ophthalmology, 90: 1192-200, 1983.

[11] ¹¹
REGAN, D. & NEIMA, D. Low contrast letter charts in early diabetic retinopathy, ocular hypertension, glaucoma and Parkinson's disease. Brit. J. Ophthalmol., 68: 885-9, 1984.

[12] ¹²
REGAN, D. Low-contrast letter charts and sinewave grating tests in ophthalmological and neurological disorders. Clin. Vis. Sci. 2: 235-50, 1988.

[13] ¹³
REGAN, D. High and low contrast acuity. Optom. Vis. Sci. 67: 650-3, 1990.

[14] ¹⁴
SAKUMA, J.T.; DA SIVA, J.A.; CRUZ, A.A.V. Measurement of visual acuity with logarithmic charts: comparison between methods of threshold estimation. Optom. Vis. Sci., 68: 666-9, 1991.

[15] ¹⁵
SHAPLEY, R.M. & ENROTH-CUGELL, C. Visual adaptation and retinal gain controls. Progress in Retinal Research, 3: 263-346, 1984.

[16] ¹⁶
TAYLOR, H.R. Applying new design principles to the construction of an illeterate E chart. Am. J. Optom. Physiol. Opt., 55: 348-51, 1978.

[17] ¹⁷
THORN, F. & SCHWARTZ, F. Effects of dioptric blur on Snellen and grating acuity. Optom. Vis. Sci., 67: 3-7, 1990.

[18] ¹⁸
WOODHOUSE, J. & BARLOW, H.B. Spatial and temporal analysis. In: Barlow, H.B. & MOLLON, J.D. The senses Cambridge, Cambridge University Press, 1987, 134 p.

[19] ¹⁹
YAMAZAKI, H.; ADACHI-USAMI, E.; CHIBA, J. Contrast thresholds of diabetic patients determined by vep and pshychophysical measurements. Acta Ophthalmologica, 60: 386-92, 1982.

Brasil