M L M Matsuhara, L F Fernandes
Sao Geraldo University Hospital, Low Vision, Belo Horizonte, Brazil
Scotoma can be defined as a area non responsive to specific luminous incentive in a normal visual field. The presence of the central escotoma takes the need of rehabilitation techniques like magnification and control of the brightness, that are ineffective for some patients. Such patient would benefit of the use of the excentric vision training. The first step for an efficient training is to become aware of the presence of the scotoma. The aim of this study was to compare the sensibility of three different methods of central scotoma location . Twenty nine patients (range 10-78 years) were directed to the Service of Subnormal Vision of São Geraldo Hospital (Minas Gerais Federal University, School of Medicine) with previous diagnoses of diseases with central scotoma. The methods Asmler grid, face observation and near acuity test observation were used. Among these methods, the one that obtained the best acting was the Asmler grid (63.6%), followed by face observation (47.3%) and near acuity test observation (30.9%) (p < 0,05). All the three methods presented low sensibility, possibly explained by the plasticity of the visual system in trying to compensate the scotoma area. The present results demonstrates that new techniques should be use to improve the sensibility of the methods The literature mentions techniques that would increase the effectiveness of the letter of Asmler such as the permission of binocular observation of the test grating before the monocular exam , the use of illumination threshold with polarized lenses and the use of red grating.
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