Corneal Hysteresis, Intraocular Pressure, and Progression of Glaucoma: Time for a “Hyst-Oric” Change in Clinical Practice?

Abstract

It is known that as people age their tissues become less compliant and the ocular structures are no different. Corneal Hysteresis (CH) is a surrogate marker for ocular compliance. Low hysteresis values are associated with optic nerve damage and visual field loss, the structural and functional components of glaucomatous optic neuropathy. Presently, a range of parameters are measured to monitor and stratify glaucoma, including intraocular pressure (IOP), central corneal thickness (CCT), optical coherence tomography (OCT) scans of the retinal nerve fibre layer (RNFL) and the ganglion cell layer (GCL), and subjective measurement such as visual fields. The purpose of this review is to summarise the current evidence that CH values area risk factor for the development of glaucoma and are a marker for its progression. The authors will explain what precisely CH is, how it can be measured, and the influence that medication and surgery can have on its value. CH is likely to play an integral role in glaucoma care and could potentially be incorporated synergistically with IOP, CCT, and visual field testing to establish risk stratification modelling and progression algorithms in glaucoma management in the future.

Corneal Biomechanics in Primary Open Angle Glaucoma and Ocular Hypertension: A Systematic Review and Meta-analysis

“…[11][12][13] Otherwise, several studies have suggested that patients with ocular hypertension (OHT) but no glaucomatous changes showed less deformable corneas. 9,10,[14][15][16] These corneal biomechanical differences indicate that the appearance and progression of glaucoma could be associated with specific corneal biomechanical DOI: 10.1097/IJG.0000000000002170 changes, 17,18 which may offer a novel perspective on glaucoma pathology.…”

Einflussnahme des Diabetes mellitus auf glaukomrelevante Untersuchungsergebnisse beim primären Offenwinkelglaukom

“…In addition, reduced CH means that the optic nerve head is less deformable, meaning that its damping ability is smaller, resulting in a firmer less flexible lamina cribrosa [44]. Furthermore, it has been shown that the lower the corneal hysteresis, the greater the cup/disc ratio [42,43]. Therefore, CH is now accorded high importance in glaucoma diagnostics.…”

“…Zudem bedeutet eine verminderte CH, dass der Sehnervenkopf weniger verformbar ist und somit seine Dämpfungskapazität kleiner ist, was eine festere, wenig nachgiebige Lamina cribrosa bedingt [44]. Weiterhin wurde gezeigt, dass je niedriger die korneale Hysterese ist, desto größer ist die Cup-Disk-Ratio [42,43]. Insofern wird der CH heute in der Glaukomdiagnostik ein hoher Stellenwert zugeordnet.…”

“…Beim POWG zeigen sich deutliche Veränderungen in der kornealen Biomechanik, indem sowohl die CH als auch der korneale Resistenzfaktor signifikant verringert sind 42 , 43 . Es konnte gezeigt werden, dass eine verringerte CH beim asymmetrischen Glaukom mit dem stärkeren Gesichtsfeldschaden assoziiert ist und generell die CH umso kleiner ist, je ausgeprägter der glaukomatöse Gesichtsfeldschaden ist.…”

It Is All about Pressure

“…The identification of markers helping in the early glaucoma diagnosis and detection of subtle signs of disease progression is a fascinating field of investigation. In the review article, Murtagh and O'Brien [22] summarize the current knowledge about corneal hysteresis (CH). CH is a relatively new ocular parameter provided by two devices available on the market, which include the Ocular Response Analyzer tonometer (ORA) and the Corneal Visualization Scheimpflug Technology tonometer (Corvis ST).…”