[Biomechanics of the lamina cribrosa: A determining factor in glaucomatous neuropathy. A review of the literature]

Changes in choroidal thickness and lamina cribrosa position in subjects with overdipper pattern of arterial pressure

INTRODUCTION

The purpose is to analyze the changes produced in subjects with an overdipper pattern of ambulatory blood pressure monitoring with the aim of understanding the pathophysiology of normal tension glaucoma.

METHODS

A cross sectional study was performed in patients exhibiting overdipper and non-overdipper blood pressure patterns, respectively. Different optic parameters were assessed including the analysis of ganglion cell layer (GCL), peripapillary retinal nerve fiber layer (pRNFL) and Bruch's membrane opening-minimum rim width (BMO-MRW), as well as changes produced in choroidal thickness (CT) and lamina cribrosa (LC) position at two different periods of the day (early morning and evening).

RESULTS

A total of 80 eyes (42 overdipper and 38 non-overdipper) were analyzed. A shortening of the distance at the beginning and end of the LC was objectified in the overdipper subjects (p < 0.003) as well as a statistically significant shift of the LC between morning and evening measurements in the overdipper subjects (p < 0.023). In addition, a significant thickening was found in 13 measurements of the horizontal and vertical plane CT (p < 0.029) of the overdipper subjects and a thickening of the CT in both groups in the morning. No significant differences in pRNFL, BMO-MRW and GCL measures were objectified.

CONCLUSIONS

Morning assessment in overdipper subjects showed a deeper LC and a LC shift in comparison to evening values. In addition, an increase in CT was found in these subjects. Altogether, these findings could illustrate an etiopathogenic mechanism of the damage produced in normal tension glaucoma associated to the overdipper pattern.