THRESHOLD PERIMETRY AND THE DIAGNOSIS OF GLAUCOMA

Visual field examinations are one of the commonest, presumably most sensitive practical indices of optic nerve dysfunction in glaucoma. Given the difficulties in training and retaining good technicians, and presumed vagaries of the Goldmann-type isopter examination technique, interest has turned to computer-controlled automated suprathreshold and threshold static perimetry. Despite the enthusiasm for these approaches, we lack rigorous tests of their value, criteria of abnormality and progressive deterioration, and even normal standards. These important issues are now being addressed. In the interim ophthalmologists must be cautious in their use and interpretation.     

EXCURSION TESTS OF OCULAR MOTILITY

Three alternative excursion tests of ocular motility have been compared. A computer model of the mechanics of the extraocular muscles has been used to estimate the tensions developed by the muscles in these tests. On the basis of these calculations we recommend the transverse test in which the positions of the eyes are observed as they track a target moving from the right to the left with a fixed elevation and a fixed depression.     

ESTIMATION OF THE STEREOSCOPIC THRESHOLD UTILIZING PERCEIVED DEPTH

Abstract Recent reports in the literature indicate that a random-dot style of stereoscopic test is the most accurate method of assessing stereoscopic threshold [Cooper, J., Feldman, J. and Medlin, D. (1979) J. Am. optom. Ass. 50 , 821–825]. While this is undoubtedly true for those who can respond to the test, it is less so for very young, infirm or other patients who do not or cannot have the requisite attention span. This experiment finds that the amount of perceived depth seen on a test like the Titmus fly correlates very accurately with the measured stereoscopic threshold and can therefore be used as a measure of the threshold without having to employ the entire testing procedure of the random dot tests. The regression equation derived from the data is presented, as well as a table that allows a practitioner to estimate the stereoscopic threshold from the amount of perceived depth on a common stereo test: the Titmus fly.     

THE WORKING THRESHOLD APPROACH TO FRIEDMANN VISUAL FIELD ANALYSER SCREENING

Central visual field screening of 2223 eyes without field defects was conducted with the Friedmann Visual Field Analyser Mark II. There was wide variation in the filter setting at which all stimuli were seen and in the working threshold relative to the recommended age filter. The ability to see all stimuli at settings higher than the age filter was found in 803 eyes (36.1%). The difference between mean working threshold and the age filter ranged from 0.22 to 0.40 log units, being greatest in middle age groups. The performance of the screener in correctly identifying normal eyes was thus improved with the working threshold approach, as the criterion for depression of sensitivity was an individually determined threshold.     

A COMPARISON OF THE BRITISH NUMBER PLATE AND SNELLEN VISION TESTS FOR CAR DRIVERS

Abstract The British number plate lest and the Snellen lest of visual acuity are compared. The observations of 60 subjects. 30 of whom have failed (he official number plate test, are analysed statistically. It is found possible to csiiiiunt1 the probability of a subject having a specified Snellen acuity, reading a number plate of the 3 1/2 (80 mm) symbol type, at 67 ft, (-20.5m). It is considered, however, that the probability of passing the official number plate test is a different value and this is also shown to be estimated from the Snellen visual acuity. The calculations based on the sample of candidates who had failed the number plate test suggest that a driving test candidate with a Snellen decimal acuity of 0.55, or approximately ft/12² in clinical notation, has a 50% chance of passing the number plate test, but the level of visual acuity which would fail the same number of candidates as the number plate test is deduced from an approximate population model, to be 0,6, or 6/9⁺². Many other quantitative estimates relating the two tests are given in the text and accompanying tables and figures.     

神经节细胞对暗视阈值反应的研究

目的：探讨神经节细胞在暗视阈值反应(scotopic threshold response，STR)形成中的作用。 方法：记录6只正常猫眼和4只视网膜光凝猫眼的STR。倍频YAG固体激光环绕视乳头周围行视网膜光凝，光凝后分别于4、8和16周记录闪光视觉诱发电位(FVEP)和系列光暗适应视网膜电图(ERG)，并于光凝后8、16周取视网膜作光镜和透射电镜观察。记录18名正常人和6例视神经萎缩患者的FVEP、系列光暗适应ERG和STR。结果：光镜和透射电镜观察证实，视网膜光凝后神经节细胞逆行性萎缩。光凝后猫眼FVEP消失、STR在正常范围。视神经萎缩患者FVEP消失，STR和正常对照组无显著性差异。 结论：神经节细胞在STR形成过程中不起作用，STR的细胞起源和神经节细胞无关。 （中华眼底病杂志，1997，13：215-218）     

COMPARATIVE STUDY OF HUMPHREY AUTOMATED PERIMETRY STRATEGIES CENTRAL 30－2 THRESHOLD TEST VERSUS CENTRAL 30－2 SITA STANDARD TEST

Objective: To compare the glaucoma hemifield test (ght) results of the central 30-2 threshold test vs. central 30-2 sita standard test in glaucoma suspect patients without expierence in automated perimetry. Methods: Using the humphrey visual field analyzer model 745, 100 subjects were tested with central 30-2 threshold test (group a) and 100 subjects were tested with cen-