NORM ACCOMMODATIVE CONVERGENCE EXCESS - L ONG-TERM FOLLOW-UP WHEN TREATED WITH BIFOCALS

Background In patients with normaccommodative convergence excess it is possible to reduce or eliminate the excess of accommodative convergen ce by adding plus lenses. The resulting reduction of near deviation ca n lead to an improvement in the quality of binocular vision at near, a nd also to a better compensation of an esophoria at near. The aim of t he paper was to study long term results in patients with small angle e sotropia and esophoria and accommodative convergence excess treated by bifocals. Methodes Clinical data of 91 patients were analysed retrosp ectively. Among them were 13 patientes with esophoria, 32 patients wit h microesotropia and 46 with microesotropia and a phoric component. An orthoptic status was performed every three months and at every examin ation it was tried to reduce the added plus lenses. The mean follow up was 5,6 +/- 2,4 years (range: 1.1-13.2). Results The mean onset of st rabismus was similar in all groups: i.e. 2.5 (+/- 1.7) years. The pati ents received their first bifocals on average 3.4 (+/- 1.9) years late r. In 40 of the 91 patients the near addition could be stopped because of sufficient decrease of accommodative convergence excess during the follow-up period. The convergence excess decreased continuously in al l patients with esophoria and microesotropia and the additional plus l enses could be stopped on average after 6.4 (3.5-8.4) years (esophoria ) and 5.0 (2.6-8.1) years (microesotropia) respectively. In patients w ith microesotropia and an additional phoric deviation bifocals were on ly partly successful to reduce the convergence excess. The basic angle decompensated in more than half of the patients (27 out of 46) and wa s operated in 14 cases by unilateral resection/recession procedure. Af ter the operation the convergence excess decreased rapidly and the bif ocals could be stopped after 4,4 (3.4-7.4) years. In the remaining 19 cases it was possible to reduced the convergence excess with bifocals in 8 patients after about 8,1 (4.1-9.3) years and in some of the remai ning 11 cases a Fadenoperation has been suggested. Conclusion While we aring bifocals the accommodative convergence excess decreased complete ly in patients with esophoria and microesotropia. In the condition wit h markedly reduced binocular vision and a large phoric component at fa r and near, the convergence excess decreased only in some of the patie nts while wearing bifocals. Conventional strabismus surgery to reduce the basic angle has a positive influence. A Fadenoperation is only nec essary in a few cases.