A retrospective study: form-deprivation myopia in unilateral congenital ptosis

Background: The aim of this retrospective study was to investigate the relationship between unilateral congenital ptosis in patients older than eight years and their refractive state and spherical equivalent refraction (SER). Methods: The study involved a review of the clinical records of 85 patients admitted to the First Affiliated Hospital, Sun Yat-sen University between 1998 and 2010 with unilateral congenital ptosis. The average age was 16.83-years (nine to 27-years). The patients were classified into mild (27 cases), moderate (37 cases) or severe (21 cases) ptosis according to the degree of the droopy eyelid covering the cornea. The fellow eyes served as controls. Results: In 85 eyes with unilateral ptosis, the frequency of myopia (SER of -0.50-D or more myopia) was significantly higher than in the fellow eye (47 versus 32, p = 0.031). The frequency of myopia in eyes with severe unilateral ptosis was significantly higher than in the fellow eyes (16 versus 7, p = 0.012), whereas there were no significant differences in patients with mild (15/27 versus 13/27, p = 0.79) or moderate (16/37 versus 12/37, p = 0.47) unilateral ptosis. Similarly, the SER was significantly more myopic in eyes with severe ptosis compared with the fellow eye (-1.37-D versus -0.85-D, p = 0.01), whereas no significant differences were found in patients with mild or moderate unilateral ptosis. Conclusions: The results showed a higher frequency of myopia and more myopic SER in eyes with severe unilateral ptosis compared with the fellow eye. The myopia found in eyes with unilateral ptosis might be caused by a mechanism similar to that resulting in myopia among animals subjected to form deprivation. It is important to pay attention to possible refractive error in patients with unilateral ptosis. Surgical correction of unilateral ptosis at an early age is recommended.