Refractive error and glaucoma.

PURPOSE: To study the association between refractive error, glaucoma damage and IOP in a large population.

METHODS

We examined 32,918 citizens of the city of Malmö, Sweden, 57-79 years of age, searching for individuals with undetected glaucoma. Refraction was measured with autorefractors. Glaucoma damage was defined as reproducible visual field defects with the Humphrey Full Threshold 24-2 program.

RESULTS

Glaucoma prevalence was clearly associated with refractive state, increasing gradually with increasing myopia. This was seen both in males and females and persisted over the full age range. Glaucoma was significantly more common in myopic than in hyperopic eyes with low IOP readings (p=0.024). The overrepresentation of glaucoma in myopic eyes declined with increasing IOP and no relationship was observed in eyes with IOP > or =31 mmHg.

CONCLUSION

In this large population, the prevalence of glaucoma increased with increasing myopia. The association between myopia and glaucoma was strong at lower IOP levels, and weakened gradually with increasing IOP. Our findings indicate that myopia is an important risk factor for glaucoma and particularly for normal tension glaucoma.