QUANTITATIVE OCULAR TESTS FOR MYASTHENIA-GRAVIS - A COMPARATIVE REVIEW WITH DETECTION THEORY ANALYSIS

Many reports in the literature describe a variety of ocular signs in m yasthenia gravis. To determine the utility of laboratory recordings of ocular signs in the evaluation for myasthenia, we reviewed all previo us studies of quantitative measures of eye movements or intra-ocular p ressures. We selected those studies with data presented for both myast henic and non-myasthenic ocular palsies. Signal detection theory was u sed to evaluate the discriminative power of each variable. The charact eristics of saccades and quick phases of optokinetic nystagmus at the start of recording were poor at distinguishing between myasthenic and non-myasthenic palsies, except when the comparison was solely between myasthenia and chronic progressive external ophthalmoplegia. The effec ts of fatigue on saccadic parameters were also not discriminative, tho ugh there was insufficient data to evaluate this adequately. Changes i nduced by edrophonium in the amplitude or peak velocity of saccades or optokinetic quick phases were good diagnostic tests, retaining high s ensitivities when criteria were set to yield a specificity of 95%, Mos t of these parameters were less efficient as screening tests, with mod est specificities when criteria were set to yield a sensitivity of 95% . The change in optokinetic quick phase amplitude recorded by infrared oculography was the best test, with ideal characteristics of 97% spec ificity and sensitivity at a criterion of zero change. This analysis s uggests that eye movement recordings of saccades or optokinetic nystag mus have potential as useful and inexpensive tests for myasthenia, and warrant further study. (C) 1998 Elsevier Science B.V.