Clinical findings before the onset of myopia in youth. I. Ocular optical components.

PURPOSE

A study was conducted to identify variables that were different in children who were emmetropic and became myopic and in children who remained emmetropic.

METHODS

A cohort of initially emmetropic children had eye and vision examinations at 6-month intervals for a period of 3 years. Ocular optical components were measured by keratometry and ultrasonography. Crystalline lens power was calculated using Bennett's formulas.

RESULTS

There was a tendency for keratometer power of both principal meridians to be greater in the became-myopic group than in the remained-emmetropic group. Axial length to corneal radius (AL/CR) ratio was significantly greater in the became-myopic group than in the remained-emmetropic group. The variable with the highest sensitivity and specificity was the AL/CR ratio using the horizontal meridian corneal radius.

CONCLUSIONS

Greater corneal powers and greater AL/CR ratios are risk factors for youth onset myopia.