视神经损伤后视觉功能重塑的研究进展

青光眼或其他原因导致的视神经损伤,以及颅脑损伤导致的视觉损伤通常被认为是不可逆的。然而,近年来的研究发现,神经系统具有明显的神经可塑性(neuroplasticity)。人们尝试对神经的可塑性作用机制进行阐明,并通过视觉经验、电流刺激、代偿性眼球运动训练及压力疏导等方法来激活或活化“休眠”细胞及视觉传递,并构建自组织映射模型对视觉重塑效果进行预估。

Corneal Biomechanical Parameters and Asymmetric Visual Field Damage in Patients with Untreated Normal Tension Glaucoma

Background： High intraocular pressure （IOP） and low central corneal thickness （CCT） are important validated risk factors for glaucoma, and some studies also have suggested that eyes with more deformable corneas may be in higher risk of the development and worsening of glaucoma. In the present study, we aimed to evaluate the association between corneal biomechanical parameters and asymmetric visual field （VF） damage using a Corvis-ST device in patients with untreated normal tension glaucoma （NTG）. Methods： In this observational, cross-sectional study, 44 newly diagnosed NTG patients were enrolled. Of these, 31 had asymmetric VF damage, which was defined as a 5-point difference between the eyes according to the Advanced Glaucoma Intervention Study scoring system. Corneal biomechanical parameters were obtained using a Corvis-ST device, such as time from start until the first and second applanation is reached （time A 1 and time A2, respectively）, cord length of the first and second applanation （length A 1 and length A2, respectively）, corneal speed during the first and second applanation （velocity A1 and velocity A2, respectively）, time from start until highest concavity is reached （time HC）, maximum amplitude at the apex of highest concavity （def ampl HC）, distance between the two peaks at highest concavity （peak dist HC）, and central concave curvature at its highest concavity （radius HC）. Results： Time A 1 （7.19 q- 0.28 vs. 7.37 ~ 0.41 ms, P = 0.010）, length A 1 （1.73 [ 1.70-1.76] vs. 1.78 [ 1.76-1.79] mm, P = 0.007）, length A2 （1.58 [1.46-1.70] vs. 1.84 [h76-1.92] mm, P 〈 0.001）, peak dist HC （3.53 [3.08-4.00] vs. 4.33 [3.92-4.74] mm, P = 0.010）, and radius HC （6.20 ± 0.69 vs. 6.59 i h 18 mm, P = 0.032） were significantly lower in the worse eyes than in the better eyes, whereas velocity A 1 and def ampl HC were significantly higher （0.156 [0.149-0.163] vs. 0.145 [0.138-0.152] m/s, P= 0.002 and 1.19 ± 0.13 vs. 1.15 ± 0.13 mm, P = 0.005, respectively）. There was no significant difference in time A2, velocity A2, and time HC between the two groups. In addition, no difference was observed in lOP, CCT, and axial length. In the univariate and multivariate analyses, some of the Corvis-ST parameters, including time A1 and def ampl HC, were correlated with known risk factors for glaucoma, and there was also a significant positive correlation between def ampl HC and age. Conclusions： There were differences in dynamic corneal response parameters but not IOP or CCT between the paired eyes of NTG patients with asymmetric VF damage. We suggest that the shape of the cornea is more easily altered in the worse eyes of asymmetric NTG patients.

Comparison of corneal biomechanics among primary open-angle glaucoma with normal tension or hypertension and controls

Background:Normal tension glaucoma(NTG)is a less pressure-dependent type of glaucoma with characteristic optic neuropathy.Recently,the biomechanical mechanism has been thought to account for glaucomatous optic neuropathy to some degree.We intended to compare dynamic corneal response parameters(DCRs)among patients with primary open-angle glaucoma with normal tension or hypertension and controls.The correlations between DCRs and known risk factors for glaucoma were also analyzed.Methods:In this cross-sectional study,49 NTG subjects,45 hypertension glaucoma(HTG)subjects,and 50 control subjects were enrolled.We compared the differences in DCRs using corneal visualization Scheimpflug technology among the NTG,HTG,and control groups.We also analyzed the correlations between DCRs and known risk factors for glaucoma(eg,central corneal thickness[CCT],intraocular pressure[IOP],etc).Results:The maximum inverse concave radius(NTG:0.18[0.17,0.20]mm-1;control:0.17[0.16,0.18]mm-1;P=0.033),deformation amplitude ratio of 2 mm(DAR 2 mm,NTG:4.87[4.33,5.39];control:4.37[4.07,4.88];P<0.001),and DAR 1 mm(NTG:1.62[1.58,1.65];control:1.58[1.54,1.61];P<0.001)were significantly higher in NTG than in the controls.The integrated radius(IR,NTG:8.40±1.07 mm-1;HTG:7.64±1.31 mm-1;P=0.026)and DAR 2 mm(NTG:4.87[4.33,5.39];HTG:4.44[4.12,5.02];P<0.007)were significantly higher,whereas the stiffness parameter at the first applanation(SP-A1,NTG:91.23[77.45,107.45];HTG:102.36[85.77,125.12];P=0.007)was lower in NTG than in HTG.There were no significant differences in the DCRs between HTG and control groups(P>0.05).In the univariate and multivariate analyses,some of the DCRs,such as IR,were negatively correlated with CCT and IOP,whereas SP-A1 was positively correlated with CCT and IOP.Conclusions:The cornea was more deformable in NTG than in HTG or controls.There were no significant differences in corneal deformability between HTG and controls.The cornea was more deformable with the thinner cornea and lower IOP.