Correlation between retinal nerve fiber layer thickness and IOP variation in glaucoma suspects and patients with primary open-angle glaucoma

Abstract

Purpose: To analyze the relationship between retinal nerve fiber layer thickness (RNFLT) and intraocular pressure (IOP) variation in glaucoma suspects (GS) and patients with primary open-angle glaucoma (POAG). Methods: Thirty-one GS and 34 POAG patients underwent ophthalmologic examination and 24-h IOP measurements. GS had IOPs ranging from 19 to 24 mmHg and/or suspicious appearance of the optic nerve. POAG patients had reproducible abnormal visual fields. We only included patients who presented with short-term IOP fluctuation >6 mm Hg (∆IOP). Only one eye per patient was included through a randomized process. Peripapillary RNFLT was assessed by spectral-domain optical coherence tomography. We correlated RNFLT with IOP parameters. Results: Mean IOP was similar between GS and POAG groups (15.6 ± 3.47 vs 15.6 ± 2.83 mmHg, p = 0.90) as was IOP peak at 6 AM (21.7 ± 3.85 vs 21.3 ± 3.80 mmHg, p = 0.68). Statistically significant negative correlations were found in POAG group between IOP at 6 AM and RNFLT in global ( rs = −0.543; p < 0.001), inferior ( rs = −0.540; p < 0.001), superior ( rs = −0.405; p = 0.009), and nasal quadrants ( rs = −0.561; p < 0.001). Negative correlations were also found between ∆IOP and RNFLT in global ( rs = −0.591; p < 0.001), and all other sectors ( p < 0.05). In GS IOP at 6 AM correlated only with inferior quadrant ( rs = −0.307; p = 0.047). Conclusion: IOP at 6 AM and ∆IOP had negative correlations with RNFLT quadrants in POAG. In GS this correlation occurred between IOP at 6 AM and inferior quadrant. These findings may indicate potential risk factors for glaucoma progression.

24-hour intraocular pressure monitoring: past, present, and future

“…(25) Cronemberger et al have studied the correlation between the thickness of the RNFL and the variation in IOP in suspected glaucoma and patients with POAG. (26) They concluded that IOP at 6:00 a.m. and ∆IOP had negative correlations with RNFL thickness quadrants in POAG. In suspected glaucoma, this negative correlation of RNFL thickness occurred between the IOP taken at 6:00 a.m. and the inferior quadrant.…”

“…These findings may indicate potential risk factors for glaucoma progression. (26) The Contact Lens Sensor (CLS) Sensimed Triggerfish® approved by the Food and Drug Administration (FDA) in 2016 has been used to detect IOP-related changes in one eye over a 24-hour period. (27) However, it does not give real IOP values and presents controversial results in relation to other methods of measuring IOP.…”