Corneal biomechanical changes and intraocular pressure in patients with thyroid orbitopathy

AIM：To determine the relevance of the objective parameters addressing the altered biomechanical properties of cornea for glaucoma monitoring in patients with mild or moderate thyroid associated orbitopathy（TAO）,and in healthy individuals.· METHODS：Twenty-five patients with TAO（group 1）and 25 healthy adults（group 2） were included to the study.Both groups were of a similar age and the ratio women：man.For each patient,the following parameters of both eyes were measured with ocular response analyzer（ORA）：corneal hysteresis（CH）,corneal resistance factor（CRF）,Goldmann correlated intraocular pressure（IOPg） and corneal compensated intraocular pressure（IOPcc）.In both groups participating in our study,all measurements were performed within minutes to reduce the diurnal effects.· RESULTS：The mean age in group 1 was 56±11y and76%were women,24%were men.The mean age in group 2 was 64±11y and 68%were women,32%were men.CH correlated negatively with IOPg in group 1（r^2=0.10,P 〈0.05）.IOPg strongly correlated with IOPcc in both groups（group 1：r^2=0.79,P〈0.0001;group 2：r^2=0.85,P〈0.0001）.There was positive correlation between CRF and IOPg in group 1（r^2=0.12,P〈0.05） and in group 2（r^2=0.31,P〈0.0001）.Statistical analysis revealed no significant correlation between CRF and IOPcc in group 1（r^2=0.009,P 〉0.05） and also no significant correlation in group 2（r^2=0.04,P〉0.05）.CRF mean value in group 2（11.51±1.72 mm Hg） was higher than in group 1（10.85±1.45 mm Hg）（P〈0.05）.IOPg strongly correlated with IOPcc in both groups（group 1：r^2=0.79,P〈0.0001;group 2：r^2=0.85,P 〈0.0001）.There was also strong correlation between CRF and CH in both populations：group 1：（r^2=0.58,P〈0.0001）,group 2：（r^2=0.41,P 〈0.0001）.· CONCLUSION：Biomechanical parameters of cornea,as quantified by CH and CRF,and measured together with IOPcc,precisely reveal glaucoma staging in TAO and thus are reliable for diagnosing and follow-up in clinical practice. 〈/tr〉

Effect of fibrin glue on corneal lamellar healing and how it correlates to biomechanical properties: biomechanical wavefront analysis and confocal study

Background:To evaluate,using a rabbit model,the influence of the wound healing process at the flap edge on corneal biomechanics after sutured,glued,and non-augmented microkeratome flaps.Methods:Unilateral 160μm thick laser in situ keratomileusis(LASIK)flaps using a mechanical microkeratome were performed on the corneas of the left eyes of 36 rabbits.Animals were then divided into 3 groups of 12 rabbits each:A:the flaps were glued with human fibrin tissue adhesive(Tisseel);B:the flaps were sutured;and C:the flaps were allowed to heal without the use of sutures or glue(non-augmented).The contralateral eyes served as controls.Reichert ocular response analyzer(ORA)was used to measure corneal hysteresis(CH),corneal resistance factor(CRF),Goldmann-correlated intraocular pressure(IOPg)and cornea-compensated IOP(IOPcc)at 6 weeks and 3 months postoperatively.In vivo confocal microscopy(IVCM)was also used to study the corneal wound healing process in all groups.Results:Both mean CH and mean CRF were significantly higher in sutured and glued groups compared with the non-augmented group at 6 weeks and 3 months postoperatively(P<0.0001).No statistically significant difference in corneal biomechanics was found between controls and groups A and B at any time points.Activated keratocytes were detected at the wound edge and peripheral flap interface in sutured and glued groups.Conclusion:The healing process at the wound edge is critical for optimal corneal integrity.Fibrin glue may serve as a safe and effective substitute to sutures in enhancing the corneal flap edge healing response and in increasing its mechanical strength.