at the first medical examination , the sister was 7 years 8 months old , and the brother was 5 years 3 months old . neither sibling had any specific birth history .
slit lamp microscopic examination revealed no abnormalities in the anterior segments of either eye , in either patient .
the best corrected visual acuities ( bcva ) were 0.1 ( right eye ) and 0.8 ( left eye ) in the sister , and 0.7 ( right eye ) and 0.1 ( left eye ) in the brother .
the cycloplegic refractive powers in the sister were : -15.50 diopter ( dpt ) , cylinder ( cyl ) + 4.50 dpt ax 85 in the right eye and -1.00 dpt cyl .
the differences in spherical equivalents between the two eyes were -12.50 diopters in the sister and -6.875 diopters in the brother .
full - time right occlusion therapy was performed in both patients for three months , then four to six hours a day for two years .
the sister was prescribed atropine for the left eye after six hours right - sided occlusion therapy a day for a year .
three years later , the bcva in the brother 's left eye had improved from 0.1 to 0.7 .
the bcva in the sister 's left eye improved from 0.1 to 0.7 during the first year ; however , she showed no further improvement after that time .
the refraction and the radius of the anterior corneal curvature were measured using an autorefractokeratometer ( speedy - k ; nikon , tokyo , japan ) and a topographer ( orb - scan ; bausch & lomb , rochester , ny , usa ) .
a - mode ultrasonography ( cinescan ; quantel medical , clermont - ferrand , france ) was performed .
the results of a - mode ultrasonography and orb - scan are presented in table 2 .
this condition is often associated with amblyopia , both in the presence of and in the absence of strabismus [ 6 , 7 ] .
the prevalence of anisometropia reported in school - based and population - based studies of school - aged children is typically 5% , but this figure varies depending on the manner in which anisometropia is defined .
myopic anisometropia is usually accompanied by strabismus , especially exotropia in 30 - 60% of patients .
this suggests that the development of binocular vision might be affected by mild infantile exotropia .
when high myopia of one eye is more than -5 to -6 diopters , or the difference in spherical equivalents of both eyes is more than 5 diopters , then anisometropia may be responsible for amblyopia .
, the present case is without any obvious complication and shows mirror image similarly . in the study of 78 monozygotic twins and 40 dizygotic twins , sorsby et al .  
reported that the concordances of corneal power , axial length , and vertical ocular refraction were higher in monozygotic twins than in dizygotic twins .
interestingly , patients in the present study had similar axial lengths in their myopic eyes . in conclusion ,
we believe that severe myopic anisometropia may be genetically determined , and further investigation is recommended .
 we report a case of one sister and brother with mirror image myopic anisometropia . 
 one sister and brother complained visual disturbance . 
 the sister was 10 years 11 months old , and brother was 8 years 4 months old . 
 full ophthalmic examinations were performed , including slit lamp examination , intraocular pressure , keratometry , anterior chamber depth , axial length , fundus examination and the cycloplegic refraction . 
 the cycloplegic refractive power was -15.50 dpt cyl.+4.50 dpt ax 85 ( right eye ) , -1.00 dpt cyl.+0.50 dpt ax 90 ( left eye ) in the sister ; -1.75 dpt cyl.+2.25 dpt ax 
 90 ( right eye ) , -9.50 dpt cyl.+4.00 dpt ax 80 ( left eye ) in the brother . 
 the co - occurrence of severe myopic anisometropia in a sister and brother is extremely rare . 
 the present case suggests that severe myopic anisometropia may be related by genetic inheritance . 
Case Report
Discussion