Mostafa Soltan Sanjari - MD,Eye Research Center, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
Maryam Ashraf Khorasani - MD,Eye Research Center, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
Shabnam khorramdel mehraban - MD,Eye Research Center, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
Kaveh Abri Aghdam - MD, PhD Eye Research Center, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran

Purpose: To determine the safety and effectiveness of minus lens therapy in children younger than six years who had X(T)Methods: A retrospective study was performed on children under the age of six who were admitted to Rasoul Akram Hospital between 2006 to 2016. Patients with X(T) who had a minimum of 12-month follow-up and had received minus therapy for at least 6 months included. Exclusion criteria: Patients were excluded from any previous history of ocular pathology, surgery, psychological disorders, developmental delays, and other types of strabismus.Definitions: Control rating: A good control score was defined when the angle of deviation was only observed during the cover test and was recovered without blinking and refixation. A fair score was assigned when deviation manifests during the cover test but it recovers with blinking or refixation. A poor score was given when deviation manifests spontaneously or does not recover with blinking and refixation. Amblyopia: Visual acuities (VA) less than 20/40 or differences higher than two lines in Snellen VA chart between two eyes were diagnosed as amblyopia.Results: Forty-six (28.4%) patients were amblyopic and underwent patching for amblyopia treatment. At the final visit, fourteen patients remained amblyopic. Adverse events were noted in seven (%4) patients) Four exotropia, and three esotropia that disappeared after cessation of therapy(. The paired t-test indicated the significant improvement in terms of VA. There was no significant correlation between sex, age and final control score of strabismus. Significantly Better control score of deviation and greater change in deviation angle after minus therapy was achieved in patients with a smaller initial angle of deviation. No significant association was found between the annual change in refractive error and lens power or treatment duration. The annual change in refractive error was significantly inversely correlated with age; younger patients had a higher change in refractive error.Conclusion: minus therapy can control intermittent exotropia without significant change in refractive error. decreases the angle of exodeviation to such a degree that they may be delayed or even eliminate the need for a surgical procedure