[Anisometropia and presbyopia: prescription of progressive lenses, a new approach]

To show that anisometropia does not absolutely preclude the prescription of progressive lenses.

Forty-one anisometropes and presbyopes were selected for a prolonged trial of visual correction using progressive lenses. The congenital or acquired type of their anisometropia and its particular form were also studied. Each patient was submitted to a protocol comprising of a series of ophthalmologic and orthoptic tests so as to evaluate the patient's subjective far and near refraction, with measurement of phorias and of horizontal and vertical ductions, visual acuity, and the quality of binocular vision while looking in different directions. A preliminary trial of correction in actual situation was done in order to check fusion in near vision. The entire range of tests was repeated two months after the patient was provided with the lenses. The tolerance for progressive lenses during the different activities of daily life was evaluated after the second and the sixth months.

Seven patients presenting an associated strabismus were not provided with the lenses because the initial pre-lens trial revealed a total inability to read within the near-vision zone. Among the 34 patients provided with the lenses, 21 constantly wore their progressive lenses and said that they were satisfied, 6 wore their progressive lenses during daily activities but preferred to use their unifocal lenses for prolonged reading, and 7 abandoned their progressive lenses because they could not tolerate them. Association with a strabismus is not synonymous with an initial impossibility or with abandonment because of the 27 patients who constantly wore their progressive lenses 9 were strabismic. The best results were obtained in the age range of 45 to 52 years old, for visual acuity for > 20/40, and in cases of congenital anisometropia with intermittent or permanent unilateral neutralization. On the other hand, patients presenting an acquired anisometropia, particularly postoperative, proved to be poor candidates.

Weak and strong anisometropia does not absolutely preclude the prescription of progressive lenses except for certain strabismic subjects with an abnormal lateral-oriented posture.