| High myopia refers to diopter of myopia more than-6D, which is one of the major complications that can caused blindness and low vision. Our country is a big country of myopia, and the study of high myopia is one of the priorities for future research in ophthalmology. Due to restrictions on means of measurement, previous studies for high myopia macular retinal morphology and function can not be quantified in vivo. The appears of OCT (optical coherence tomography) and mfERG (multifocal electroretinography) can solve the problem. In this study, we test the morphology and function changes of the macula in high myopia accuratly by combining these two means of checking.Part I Clinical study of the macular retinal thickness in non-pathological myopic subjectsObjective:To investigate the changes of retinal thickness in macula of high myopic eyes using spectral domain optical coherence tomography (OCT).Methods:Middle-aged and young myopic patients were divided into three groups according to their refractive error/axial length:low and medium myopia group (LMMG), high myopia group (HMG) and super high myopia group (SHMG). Cirrus HD-OCT was used to evaluate total average macular thickness, central subfield thickness, inner/outer macular thickness and macular volume. The differences among experimental groups were analyzed by one-factor analysis of variance. Associations between macular thickness and refractive error/axial length were analyzed by Pearson correlation analysis.Results:There was no significant difference in age among the three groups (P=0.2789). The mean refraction error in the LMMG, HMG, and SHMG groups was-2.49±1.38D,-8.53±1.95D and-13.88±1.76D, respectively (P<0.001). The central subfield thickness of three groups was244.56±12.19μm,254.33±11.61μm and261.75±11.83μm, respectively, and there were statistically significance between random two groups. The total average macular thickness, inner/outer macular thickness, and macular volume decreased with increased myopia/axial length. The central subfield thickness had negative correlations with refractive error (P<0.001), and positive correlations with axial length. The inferior and temporal inner macular thickness, all the quadrants of outer ring, total average macular thickness and macular volume featured positive correlations with refractive error, and negative correlations with axial length. Central subfield thickness, superior and temporal inner macular thicknesses, and temporal outer macular thickness was lower in females compared to males.Conclusions:With an increase in myopia degree/axial length, the central subfield thickness increased and the inner/outer macular thickness decreased. Females featured thinner macular thickness compared to males. PartⅡ Clinical study of the changes of retinal function in non-pathological myopic subjectsObjective:To investigate the changes of retinal function in macular of high myopic eyes using multifocal electroretinography.Methods:113myopic patients (113eyes) with an age range of18to35years old were enrolled in the study. Patients were divided into four groups according to their refractive error/axial length: emmetropia group (EG, spherical equivalent between+0.75--0.50D and axial length between22-24mm, n=31), low and medium myopia group (LMMG, spherical equivalent between-0.50--6.00D and axial length between24-26mm, n=26), high myopia group (HMG, spherical equivalent between-6.0--10.00D and axial length between26-28mm, n=34), and super high myopia group (SHMG, spherical equivalent≥-10.00D and axial length≥28mm, n=22). All patients underwent a complete ophthalmic examination, including:visual acuity, best corrected visual acuity (BCVA), anterior segment slit lamp examination, refraction, intraocular pressure (Goldmann applanation tonometer), gonioscopy, visual field and dilated fundus examinations. The differences of P1response density, P1amplitude, and P1implicit time among the four diagnostic groups were analyzed by one-factor analysis of variance(ANOVA) followed by SNK test. P<0.05was considered to be a statistically significant difference.Results:With the increasing of eccentricity, P1response density of each group decreases. The analysis of ANOVA showed the difference of P1response density of1ring,2ring,3ring between each group was statistically significant (P=0.0000, P=0.0001, P=0.0021).SNK test showed that for each pairwise comparison group the differences of1ring of P1response density were statistically significant. The differences of2ring of P1response density were significant between emmetropia group and super high myopia group, low and medium myopia group and super high myopia group, high myopia group and super high myopia group (P<0.01, P<0.01, P<0.01). The differences of3ring of P1response density were significant between emmetropia group and super high myopia group, the low and medium myopia group and super high myopia group (P<0.05, P<0.01). The differences of4ring and5ring of P1response density were not statistically significant (P=0.7008, P=0.8835).With the increasing of eccentricity, P1amplitude in each group were gradually reduced. The analysis of ANOVA showed that the differences of P1amplitude of1-5ring between groups were statistically significant (P=0.0000, P=0.0000, P=0.0000, P=0.0000, P=0.0000). Pairwise comparison shows only the difference between high myopia group and super high myopia group was not significant.With the increase of refraction, P1implicit time gradually extended. The analysis of ANOVA showed the difference of1ring,2ring and3ring of each group was statistically significant (P=0.0000, P=0.0000, P=0.0000). Pairwise comparison showed that the difference of P1implicit time of1-5ring between low and medium myopia group and high myopia group was not statistically significant. The difference of P1implicit time of1-3ring was statistically significant between emmetropia group and super high myopia group, low and medium myopia group and super high myopia group, high myopia group and super high myopia group.Conclusions:1. With the increases of the severity of myopia, P1response density and P1amplitude of the first-order reaction gradually reduces (P<0.05). This showed potential decline in retinal function in myopia-To some extent it may reflect the functional disorder or depression of the visual cells. The exact mechanism needs further study.2. The results of this study showed that myopia had a negative effect on mfERG results. In addition to considering the effect of age when analyzing the results of mfERG, we must also consider the effect of myopia. |
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