Abstract
Purpose :
To compare corneal/scleral stiffness from air puff deformation in Normal (NL), Primary Open Angle Glaucoma (POAG) without history of prostaglandin analog (PGA) treatment and with current/former PGA treatment (POAG-PGA), as well as Ocular Hypertension with (OHT-PGA) and without PGA treatment (OHT).
Methods :
A prospective crossectional study of 253 subjects was conducted: 387 eyes of 194 NL, 54 eyes of 29 POAG-PGA, 19 eyes of 11 POAG, 12 eyes of 6 OHT-PGA, and 26 eyes of 13 OHT subjects. Ganglion Cell Complex (GCC) from Optical Coherence Tomography was measured on all subjects. Cup/disc ratio (C/D) and mean deviation (MD) from visual field exams were extracted from the medical records of both OHT and both POAG cohorts. Biomechanical response from Corvis ST was evaluated with corneal parameters, Integrated Inverse Radius (IntInvRad) and stiffness parameter (SP) at first applanation (SP-A1). Scleral stiffness at highest concavity (SP-HC) was included. MANCOVA was performed with IOP from Dynamic Contour Tonometry (DCT), pachymetry and age as covariates for biomechanical parameters. GCC, C/D, and MD were compared with age as a covariate. Statistical significance threshold was set to p<0.05.
Results :
SP-A1 was not different between any group. NL showed a less stiff corneal response in IntInvRad than OHT (p=0.0030) and OHT-PGA (p=0.0059), which were not different than each other. OHT had a significantly stiffer scleral response in SP-HC (p < 0.0001) than all other cohorts, including OHT-PGA (p=0.0003) which was stiffer than NL (p=0.0152) and POAG (p=0.0053). NL, POAG and POAG-PGA were not different than each other. GCC was thickest (p < 0.0001) in NL than all cohorts except OHT, which was thicker than OHT-PGA (p=0.0085) and both POAG cohorts (p < 0.001). C/D was not different between POAG and POAG-PGA, but greater than both OHT cohorts (p < 0.0005) which were not different from each other. MD was significantly worse in POAG-PGA than POAG (p=0.0029). No other cohorts were different.
Conclusions :
PGA treatment resulted in a less stiff scleral response in OHT with thinner GCC, consistent with site of action of PGA and reports of greater response in stiffer eyes at baseline. Although there was no difference in scleral stiffness with PGA in POAG, MD was worse with PGA treatment. It is not clear whether PGA resulted in thinner GCC in OHT and worse MD in POAG, or if these eyes were more advanced at baseline.
This is a 2021 ARVO Annual Meeting abstract.