Reduction in central corneal thickness may not relate to glaucoma progression

Central corneal thickness may decrease over time, especially in eyes with primary open angle glaucoma, but the decrease may not be related to disease progression, according to a long-term study.

Leon W. Herndon, MD, and colleagues at the Duke University Eye Center, studied 64 eyes of 39 patients with open angle glaucoma, ocular hypertension, suspected glaucoma or a normal eye. Patients were examined at two visits (mean 8.2 years apart).

Patients were evaluated for central corneal thickness, age, race, sex, family history of glaucoma, presence of diabetes and systemic hypertension, diagnosis, visual acuity, spherical equivalent, IOP, vertical and horizontal cup to disc ratios, number of glaucoma medications prescribed, Advanced Glaucoma Intervention Study score and mean deviation of Humphrey visual fields.

The mean central corneal thickness decreased between the two visits by 17 µm in right eyes and by 23 µm in the left eyes. Both were statistically significant. Additionally, the central corneal thickness decrease was greater in the right eyes of patients who had primary open angle glaucoma.

There were no significant changes in any outcome variable in central corneal thickness for patients in any group, “so this decrease in central corneal thickness does not seem to be related to glaucomatous progression,” the researchers said.

They did acknowledge that a potential weakness of the study is that different pachymeters were used during both visits, as the original pachymeter is no longer available. However, ultrasound pachymetry has a precision of 5 to 10 µm, which is less than the mean decrease in this study cohort.

This study was published in the June issue of British Journal of Ophthalmology.