ABSTRACT
AIM: To investigate and analyze the changes of corneal biomechanics of normal eyes,forme frusta keratoconus eyes,subclinical keratoconus eyes and clinical keratoconus eyes by Corneal visualization Scheimpflug technology (Corvis ST),and provide clinical basis for early diagnosis of keratoconus.METHODS: Case-control study.We randomly selected 40 normal eyes as normal group,15 forme frusta keratoconus eyes as forme frusta keratoconus group,23 subclinical keratoconus eyes as subclinical keratoconus group,and 40 clinical keratoconus eyes as keratoconus group.The biomechanical parameters of each group were measured by Corvis ST.The receiver operating characteristic(ROC) curves was plotted to distinguish keratoconus from the normal cornea.RESULTS: There was no significant difference in the parameters of biomechanics between normal group and forme frusta keratoconus group (P>0.05).Compared to normal group and subclinical keratoconus group,the parameters second applanation length(AL2),first velocity of applanation (AV1),central curvature radius at highest concavity (HC-radius),deformation amplitude (DA) were revealed statistically significant differences(P<0.05).The biomechanical parameters of the keratoconic group were significantly different from those of normal group except for the second velocity of applanation (AV2),time from the start until the highest concavity(HC-time),peak distance (PD).ROC curve showed that the DA(area under the curve:0.891±0.028) was the best predictive parameter to distinguish keratoconus from the normal eyes.CONCLUSION: The corneal biomechanical parameters of forme frusta keratoconus group are not changed compared with normal group.The changes between normal group and subclinical keratoconus group should combine with other technology to further improve subclinical keratoconic screening.Compared with normal corneas,keratoconus has a great change in biomechanics,which DA diagnosis of the highest efficiency.
ABSTRACT
Background More and more attentions are paid to the effect of matrix metalloproteinases (MMPs) in the process of wound healing after excimer laser.Objective The present study was to investigate the effects of GM6001,a matrix metalloproteinases inhibitor,on haze formation after excimer laser epithelial keratomileusis (LASIK).Methods LASEK of -10.00 diopter was bilaterally performed on 27 New Zealand white rabbits and then divided randomly into the GM6001 group,Fluorometholone (FML) group and normal control group.Corneal haze was graded under dim light at 2 weeks,4 weeks and 8 weeks after operation,and the number of eyes in different grades of haze were compared among the three groups.Six corneal samples were harvested in each group for confocal microscope examination at 2,4,8 weeks.The corneal histopathological examination was carried out with the optical microscope,and the ultrastructure of the cornea was examined under the transmission electron microscope.Results The numbers of eyes of different corneal grades of haze at 2,4 or 8 weeks after surgery were significantly different among the three groups (P＜0.05).Compared with the normal control group,the corneal haze grades in the GM6001 group and FML group were apparently lower (P＜0.01),but there was no significant difference in the numbers of eyes of different corneal grades of haze between the GM6001 group and FML group (P＞0.01).The numbers of keratocytes in the GM6001 group were apparently lower than those in the normal control group and FML group in 2,4 or 8 weeks after operation (P＜0.05).No significant difference in the keratocytes was seen between the normal control group and FML group at various time points (P＞0.05).Corneal epithelial cell morphology,disordered arrangement of collagen fibers in GM6001 group and in FML group were less pronounced than in the negative control group.Conclusion GM6001 has an inhibitory effect on the formation of corneal haze after LASEK which suppresses proliferation and production of keratocytye with the similar efficacy as FML.