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Ocular rigidity and ocular response analyzer
Author(s) -
IOMDINA E,
ARUTUNYAN L,
IGNATIEVA N,
DANILOV N
Publication year - 2009
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2009.2154.x
Subject(s) - sclera , ophthalmology , glaucoma , open angle glaucoma , medicine , ocular hypertension , intraocular pressure , cornea
Abstract Purpose To study ocular rigidity and sclera crosslinking level at diferent stages of primary open angle glaucoma (POAG). Methods Biomechanical parameters of the eye especially corneal hysteresis (CH, mm Hg) were measured in 238 patients (311 eyes) aged 40‐84 (median age 67.4 yrs) at various stages of compensated primary open‐angle glaucoma using Reichert Ocular Response Analyzer (ORA). Besides, scleral samples obtained during sinus trabeculectomy combined with sclera trephination in the inferio‐exterior quadrant of 28 patients (28 eyes) with various stages of POAG were studied using differential scanning calorimetry (Mettler TA 4000 with DSC20 cell). Results Average value (median) of CH gradually decreased from 10.1 mm Hg in the initial glaucoma stage (I) to 9.1 mm Hg in the developed (II) and 8.6 mm Hg in the advanced (III) glaucoma stage. The decrease of this clinical parameter is caused by structural and biochemical damage of the corneoscleral coat. In stage I, endothermic scleral collagen transition occurred at the median thermal peak Tm=60.3 grad.C, while in stages II and III the median peaks of scleral collagen melting emerge at higher temperatures: Tm=62.0 grad.C and Tm=64.5 grad.C, respectively (p<0,05). This testifies to a significant increase of scleral cross‐linking and ocular rigidity during glaucoma development. Conclusion Biomechanical and biochemical disorders of glaucomatous sclera may cause clinical changes of ocular rigidity of eyes with POAG. This may be an important link of POAG pathogenesis requiring special therapy.