Intermittent Exotropia, When to Recommend Glasses and When to Perform Surgery?

Abstract
Aim of Work: The aim of this study is to determine which type of intermittent exotropia that may be corrected by glasses and which type that is best corrected by surgery and to evaluate the condition of binocular functions both before and after wearing glasses and before and after surgery.
Patients and Methods: Fifty patients (3 to 25 years) with intermittent exotropia were evaluated using a new scale to assess the level of control for both distance and near fixation. Near stereoacuity was evaluated with Tetmus Fly test. Diag-nosis of IXT was based on history taking from patients or their parents and clinical examination.
Results: The 50 patients with intermittent exotropia had mean age of 9.56-}6.48 with range between (3-25) years. Twenty six patients (52%) were below 10 years and 24 patients (48%) were above 10 years, 34 patients (68%) were males and 16 patients (32%) were females. The mean spherical was –2.88±7.3 1 . The BCVA ranged from 0.40 to 1.0 log MAR (mean 0.69±0.16). Pretreatment distance deviation of exotropia ranged from15 to 80A (mean 3 8.40±16. 14). Twenty four patients (48%) underwent surgery, glasses were prescribed for 8 patients (16%) and over-correcting minus lenses were prescribed for 18 patients (36%).
Conclusions: Over correcting minus lenses should be prescribed for IXT patients with the following criteria: high AC/A ratio, moderate to good control of exotropia, a tempo-rizing measure for young patients waiting for surgery and sometimes for patients with undercorrection after surgery. Glasses should be prescribed for IXT patients with the fol-lowing criteria; refractive error either astigmatism or myopia, moderate to good control of exotropia, and small angle of deviation. IXT patients with the following criteria should be corrected by surgery: Gradual loss of fusional control as evidenced by increasing frequency of the manifest phase of the strabismus, an increase in size of the basic deviation, development of suppression and decrease of stereoacuity.