May 31, 2019 Conference
Dr. Hyunjoo Lee, Boston University
Dr. Manishi Desai, Boston Medical Center and Boston University School of Medicine
Dr. Babak Eliassi-Rad
Purpose: Normal tension glaucoma (NTG) is a subset of open-angle glaucoma that is less dependent on intraocular pressure (IOP), making screening difficult. Although increased IOP has been associated with decreased corneal endothelial cell (CEC) density, two previous studies correlating a reduction in CEC density and NTG reported conflicting results. We performed an observational cross-sectional study to examine the correlation of NTG with a reduction in corneal endothelial cell (CEC) density.
Methods: 24 NTG patients and 26 age-matched controls were examined at the eye clinic in Boston Medical Center between January 2016 - November 2018. Exclusion criteria included those with a documented IOP above 21mmHg, prior eye surgery, lasers, ocular trauma, corneal diseases, uveitis or inflammation. CECs were imaged using a noncontact specular microscope. In patients with bilateral disease, the right eye was analyzed unless met with exclusion criteria in which case the left eye was analyzed. Outcome measures included CEC density, size and shape, and differences between NTG eyes and controls were analyzed using the Student’s t-test.
Results: Baseline characteristics including age, sex, and ethnicity were homogenous between the 24 NTG and 26 control subjects. The average CEC density in NTG eyes (2307 ± 514.7) was significantly reduced (p = 0.0440) compared to controls eyes (2570 ± 276.4). The average CEC size in NTG eyes (458.3 ± 94.82) was significantly larger (p = 0.0042) compared to control eyes (384.0 ± 57.41). The coefficient of variance in NTG eyes (43.75 ± 14.82) was not significantly greater (p = 0.9564) compared to control eyes (43.58 ± 6.178).
Conclusion: There was a significant decrease in CEC density in NTG eyes compared to normal eyes. NTG eyes had significantly increased polymegathism but no significant increase in pleomorphism compared to normal eyes. Thus, there may be a mechanism for decreased CECs in glaucomatous eyes other than elevated IOP. These findings may offer an additional risk factor to consider in screening for NTG, and may instigate further work in analyzing the relationship between CECs and trabecular meshwork cells, which arise from a common neural crest lineage.