Pathogenesis of transient high myopia after blunt eye trauma.

OBJECTIVE

To determine the pathogenesis of transient high myopia after blunt eye trauma.

DESIGN

Two observational case reports and literature review.

METHODS

Refraction was measured in two patients with an autorefractometer in the acute and convalescent stages after a blunt eye injury. The anterior chamber angle, the ciliary body, and the choroid were examined by ultrasound biomicroscopy (UBM) in the acute and convalescent stages. In one patient, the anterior chamber depth, lens thickness, and axial length were measured by A-scan ultrasonography in the acute and convalescent stages.

MAIN OUTCOME MEASURES

Comparison of the refraction, anterior chamber depth, lens thickness, axial length, and the UBM-determined appearance of the choroid and ciliary body during the acute stage with the values during the convalescent stages.

RESULTS

The first patient showed a myopic shift of -9.75 diopters (D) and an anterior chamber shallowing of 0.94 mm measured 3 days after trauma by an air bag inflation compared with the measurements at the convalescent phase. UBM showed an annular ciliochoroidal effusion with ciliary body edema, anterior rotation of the ciliary processes, and disappearance of the ciliary sulcus. Eleven days after the injury, these UBM findings normalized, and the myopia decreased to -0.75 D, 27 days after trauma. The second patient had a myopic shift of -8.9 D compared with the convalescent phase, immediately after blunt trauma by a firework. Seven days after the injury, UBM revealed a partial cyclodialysis in addition to findings similar to those in the first patient. Ten days after injury, a myopic shift (-4.75 D), anterior chamber shallowing (by 1.1 mm), and thickening of the crystalline lens (by 0.27 mm) were observed compared with the convalescent phase. Associated UBM findings confirmed the anterior shift of the lens-iris diaphragm. Seventeen days after trauma, the UBM findings, including the cyclodialysis, were normalized, and the myopia had decreased to -1.0 D.

CONCLUSIONS

Transient high myopia after blunt trauma is caused by anatomic changes in the ciliary body and crystalline lens. The anterior shift of the lens-iris diaphragm caused by ciliochoroidal effusion with ciliary body edema and thickening of the crystalline lens from blunt eye trauma are involved in traumatic high myopia.