Relationship between corneal hysteresis and positional change in intraocular pressure in healthy adults

Abstract

Purpose : Prior studies show that low cornea hysteresis (CH) is associated with increased risk of glaucoma, progression, and a greater intraocular pressure (IOP) reduction following treatment. CH reflects the viscoelastic tissue properties with low CH in glaucoma associated with higher IOP and greater IOP response. However, the biomechanical relationship between CH and positional IOP variation is not known. We hypothesize an association between CH and positional change in IOP (ΔIOP) with higher CH associated with smaller ΔIOP in healthy eyes.

Methods : Participants with healthy eyes were enrolled in a multi-center trial (NCT 01677507) at Mayo Clinic, University of Michigan, and University of Nebraska. All underwent a comprehensive eye exam, CH, biometry measurements, IOP_seated and IOP_supine measured by pneumatonometry, and physical measurements. The outcome measures included IOP_seated, IOP_supine, ΔIOP (IOP_supine-IOP_seated), and percent ΔIOP. Analysis included multiple linear regression and quantile regression to investigate the relationship between CH with both ΔIOP and percent ΔIOP.

Results : 92 participants (23 men, 69 women) were analyzed with a mean ± standard deviation of 56.3 ± 8.8 years. CH was 10.8 ± 1.6 mmHg in right eyes and 10.9 ± 1.7 mmHg in left eyes. IOP_supine was 20.9 ± 3.1 mmHg and IOP_seated was 15.9 ± 2.7 mmHg with ΔIOP of 5.0 ± 1.8 mmHg in right eyes. IOP_supine was 20.9 ± 3.1 and IOP_seated was 15.8 ± 2.6 mmHg with ΔIOP of 5.2 ± 1.9 in left eyes. The percent ΔIOP was 33% for right eyes and 34% for left eyes. There was no significant association between CH and ΔIOP by multiple linear regression analysis (see Figure R², OD =-0.007, OS=0.041). After adjusting for percent ΔIOP the association remained insignificant. There was no association between CH and co-variates of sex, age, biometry, blood pressure, systemic medications, and body mass index to explain ΔIOP (see Table).

Conclusions : In participants with healthy eyes, our results do not support the hypothesis that CH is associated with IOP variation as measured by positional change in IOP. In these individuals with healthy eyes, the data represents normal-to-high CH values, so there is a limited range of CH specifically on the low CH values. The next phase of EDEN is enroll cases with glaucoma and ocular hypertension and thus test the association of CH and IOP variation in a case-control study design.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.