Although monovision (MV) contact lens correction of presbyopia has been demonstrated to have a high rate of patient success, roughly 20% of those who are fitted with MV lenses fail to accept the treatment. We have investigated the effects of MV correction on various clinical functions in order to develop a series of visual and binocular performance measurements for screening potential MV patients. Two case reports are presented which compare a successful and an unsuccessful MV patient. Both patients were of similar age, refractive status, add and baseline binocular clinical measurements. MV correction of the unsuccessful patient induced greater stereoacuity loss, greater esophoric shift and greater reduction of high and low contrast distance and near LogMAR visual acuity compared to the successful MV corrected patient. These results, in conjunction with those of previous clinical studies, suggest a profile of the unsuccessful MV patient based on three routine clinical tests. Large reductions in visual acuity and stereoacuity and a tendency towards distance esophoria with MV correction dictate a poor prognosis for potential MV success.