Optical coherence tomography imaging in keratoconus / 国际眼科杂志(Guoji Yanke Zazhi)

Keratoconus is a chronic, non-inflammatory corneal disease, characterized by thinning of the corneal stroma and local corneal dilation with cone-shaped protrusion, and it usually leads to irregular astigmatism and myopia, posing great threat to eyesight. Corneal topography is the primary diagnostic tool for confirming keratoconus, while optical coherence tomography is now playing an increasingly important role in the diagnosis and treatment of keratoconus due to its ability of corneal sublayer imaging and superiority in repeatability, resolution, and data acquisition speed. This article discusses and reviews the clinical characteristics of keratoconus, the classification and characteristics of optical coherence tomography and its novel applications in the early diagnosis of keratoconus, contact lens fitting, corneal cross-linking therapy, and corneal transplantation; furthermore, progress in derivative technologies including optical coherence elastography, optical coherence tomography angiography, and polarization-sensitive optical coherence tomography associated with keratoconus is included in this article. We hope our study will help to further exploit the role of optical coherence technology in clinical keratoconus management.

Inhibition of corneal fibrosis by Smad7 in rats after photorefractive keratectomy / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Haze or corneal subepithelial fibrosis is one of the common complications after refractive surgery procedures, such as photorefractive keratectomy (PRK), laser epithelial keratomileusis, and epipolis laser in situ keratomileusis, which would result in refractive regression, decreased visual quality, and corneal opacification. Haze directly resulted from corneal fibrosis mediated by transforming growth factor β (TGFβ). Smad7, an inhibitory Smad, can inhibit TGFβ signal transduction. Recently, the effects of Smad7 on the inhibition of fibrosis in several organs have been studied, while little is known about the effects on cornea after PRK. This study was aimed to determine the effects of lentiviral-mediated Smad7 gene expression on corneal fibrosis in rats after PRK.</p><p><b>METHODS</b>Four different experimental groups were established using right eyes of Sprague-Dawley rats. Thirty-two eyes underwent de-epithelialization only and served as a sham operation group (group 1). Ninety-six eyes underwent PRK operation and were further divided into group 2 (the PRK group) without lentivector administration, group 3 (the Lv-blank group) with control lentiviral vector without Smad7 administration, and group 4 (the Lv-Smad7 group) with Smad7 expressing lentiviral vector Smad7 administration. At 1 day, 1 week, 1 month, and 3 months after PRK, the transfection efficiency was determined by measuring the fluorescence signal as well as Smad7 protein and mRNA levels. Corneas were further processed for immunoblotting to assess the phosphorylation of Smad2 as a downstream event of TGFβ/Smad signaling. The expression of fibrotic markers, such as α-smooth muscle actin (α-SMA), Type III collagen (collagen III), and cell cycle-related marker Ki67, was measured by quantitative real-time reverse transcription polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>Lentivirus-mediated exogenous Smad7 gene expression in rat corneal tissue resulted in reduced activation of TGFβ/Smad signaling caused by downregulation of phosphorylation of Smad2. Smad7 also downregulated the expression of TGFβ2. Markers of cell proliferation and fibrosis, including Ki67, α-SMA, and collagen III, were inhibited by Smad7 up to 3 months after PRK operation.</p><p><b>CONCLUSION</b>Smad7 gene transfer inhibits fibrogenic responses of cornea in rats after PRK.</p>

Further enhancing patient satisfaction after laser corneal refractive surgery / 中华实验眼科杂志

Corneal refractive surgery has been the major solution for the correction of ametropia.With the standardization of preoperative examination,intraoperative procedure and perioperative drugs,corneal refractive surgery has become much safer.Meanwhile,patients can get not only good visual acuity,but also favorable visual quality.However,the patient satisfaction has not been improved dramatically with the enhance of effectiveness and safety after surgery.Increase of the satisfaction degree to corneal refractive surgery is related to multiple factors such as experienced and highly skilled operation,operative safety,lessening operative complication,good postoperative visual and life quality of patients.Comprehensively analyzing existing problems in corneal refractive surgery in China and further obtain satisfaction of patient will be of an important significance for the healthy development of laser corneal refractive surgery.

Expression of Smad7 inhibits fibrogenic responses of keratocytes to transforming growth factor β2 / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Transforming growth factor β (TGFβ) is one of the most important growth factors in the development of fibrosis and scarring on cornea. Smad7, an inhibitory Smad, can inhibit TGFβ signal transduction. In recent years, effects of lentiviral-mediated Smad7 on inhibition of fibrosis on some organs have been studied, while little is known about the effects on cornea. This study aimed to determine the effects of lentiviral-mediated Smad7 gene expression on keratocyte proliferation and fibrosis induced by TGF β2 in vitro.</p><p><b>METHODS</b>Keratocytes were cultured from corneal tissue isolated from Sprague-Dawley (SD) rats and transfected with Smad7 expressing lentiviral vector (Lv-Smad7) or non-functioning control vector (Lv-blank). Following the exposure to TGFβ2, keratocytes were processed for immunoblotting to assess the phosphorylation of Smad2 as down-stream event of TGFβ/Smad signaling. Expression of fibrotic markers α-smooth muscle actin (α-SMA), type III collagen (collagen III) were measured by Western blotting and quantitative real time polymerase chain reaction (PCR). Overall cell proliferation was determined by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the expression of cell cycle-related marker Ki67 at both mRNA and protein levels.</p><p><b>RESULTS</b>The Smad7 gene transfer suppressed TGFβ/Smad signaling in keratocytes by down-regulating phosphorylation of Smad2. Markers of cell proliferation and fibrosis including Ki67, α-SMA, collagen III were inhibited by introduction of Smad 7 into TGFβ exposed keratocytes. Consequently, the rate of cell proliferation was attenuated.</p><p><b>CONCLUSION</b>Smad7 gene transfer inhibited fibrogenic responses of keratocytes to TGFβ2.</p>

Effects of age on ocular anterior segment dimensions measured by optical coherence tomography / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Older subjects tend to have smaller ocular anterior segment. The present study aimed to measure anterior segment dimensions with optical coherence tomography (OCT) and quantitatively assess the effect of age and other factors.</p><p><b>METHODS</b>Anterior segment OCT images were obtained in normal subjects residing in the greater Los Angeles area. Four line scans were acquired at the 90°, 45°, 0° and 135° meridians of each eye. Computer calipers acquired anterior segment dimensions of corneal diameter, anterior chamber width, corneal vault and anterior chamber depth on OCT images. Measurements from 4 meridians were averaged. Axial length and corneal power were measured by partial coherence interferometry. Univariate and multivariate analyses were performed to assess correlations.</p><p><b>RESULTS</b>Sixty-six eyes of 33 normal subjects (aged 22 - 65 years, 19 Asians, 14 Caucasians) were enrolled. For every 1 year of age, corneal diameter was 0.033 mm narrower (P < 0.01), anterior chamber width was 0.031 mm narrower (P < 0.01), corneal vault was 0.016 mm lower (P < 0.01), and anterior chamber depth was 0.025 mm lower (P < 0.01). Asian eyes had smaller corneal diameter (P = 0.035) and anterior chamber width (P = 0.015) compared with those of Caucasian eyes. Body height showed positive correlation with corneal diameter (0.039 mm per centimeter of height, P < 0.01) and corneal vault (0.024 mm per centimetre of height, P < 0.01). Gender did not have an independent effect on anterior segment dimensions.</p><p><b>CONCLUSIONS</b>Anterior segment dimensions were smaller in older subjects. Age-related changes may affect the tolerability of long-term implants such as phakic intraocular lens.</p>

Relationship between best corrected visual acuity and refraction parameters in myopia / 法医学杂志

OBJECTIVE@#To explore the relationship between best corrected visual acuity (BCVA) and refraction parameters in myopia.@*METHODS@#Two thousand two hundred and seventy-four patients (4245 eyes) with different degrees of myopia were collected. Their BCVA, diopter of spherical (DS), diopter of cylinder (DC), astigmatism axis, axial length (AL) and corneal thickness were detected. The influence of those parameters on BCVA was studied and the mathematical model of the relationship between BCVA and other parameters including the age and gender of patients was established.@*RESULTS@#The logistic regression analysis showed that there were correlations between the BCVA (y) and DS (x1), DC (x2), gender (x3), AL (x4), corneal thickness (x5), astigmatism axis (x6) and age (x7) (P<0.05): y=0.580 6-0.034 0 x1-0.046 8 x2+0.056 5 x3+0.016 5 x4+ 0.0007 x5+0.000 2 x6-0.005 8 x7.@*CONCLUSION@#For people with myopia, age, gender and corneal thickness have small effect on BCVA, while the DS, DC, AL and astigmatism axis have significant effect on BCVA. The BCVA would decline following the extension of DS, DC and AL. It is helpful to assess the vision of myopia by analyzing the refraction parameters comprehensively.

The relationship between eyeball structure and visual acuity in high myopia / 法医学杂志

OBJECTIVE@#To explore the relationship between eyeball structure and visual acuity in high myopia.@*METHODS@#Totally, 152 people (283 eyeballs) with different levels of myopia were tested for visual acuity, axial length, and fundus. All cases were classified according to diopter, axial length, and fundus. The relationships between diopter, axial length, fundus and visual acuity were studied. The mathematical models were established for visual acuity and eyeball structure markers.@*RESULTS@#The visual acuity showed a moderate correlation with fundus class, comus, axial length and diopter ([r] > 0.4, P < 0.000 1). The visual acuity in people with the axial length longer than 30.00 mm, diopter above -20.00 D and fundus in 4th class were mostly below 0.5. The mathematical models were established by visual acuity and eyeball structure markers.@*CONCLUSION@#The visual acuity should decline with axial length extension, diopter deepening and pathological deterioration of fundus. To detect the structure changes by combining different kinds of objective methods can help to assess and to judge the vision in high myopia.

Eyeball structure changes in high myopic patients and their significance for forensic assessment / 法医学杂志

There are irreversible eyeball structural changes in high myopic patients. These changes include axial length, corneal radius, anterior chamber depth, fundus degeneration, macula thickness, etc. There is a close relationship between the damage degree of visual function and these changes. The incidence of complications, such as vitreous opacity, posterior vitreous detachment, cataract, glaucoma, posterior staphyloma and retina detachment, is also highly related to the myopia diopter. More and more researches have indicated that the myopia diopter and the level of visual function are affected by multiple factors. It is promising to detect all of these changes by different kinds of methods, and to assess visual function through these changes. By clarifying these changes, it is also useful to distinguish traumatic damage from disease to provide evidence for forensic assessment of eye injuries.