Scleral ultrastructure and biomechanical changes in rabbits after negative lens application.

AIM: To address the microstructure and biomechanical changes of the sclera of rabbits after negative lens application by spectacle frame apparatus. METHODS: Five New Zealand rabbits of seven weeks post-natal were treated with -8 D lens monocularly over the course of two weeks. Refractive errors and axial length (AXL) were measured at the 1st, 7th and 14th days of the induction period. Ultrastructure of sclera was determined with electron microscopy. Biomechanical properties were tested by an Instron 5565 universal testing machine. RESULTS: Lens-induced (LI) eyes elongated more rapidly compared with fellow eyes with AXL values of 15.56±0.14 and 15.21±0.14 mm (P<0.01). Fibril diameter was significantly smaller in the LI eyes compared with control ones in the inner, middle, and outer layers (inner layer, 63.533 vs 76.467 nm; middle layer, 92.647 vs 123.984 nm; outer layer, 86.999 vs 134.257 nm, P<0.01, respectively). In comparison with control eyes, macrophage-like cells that engulfed fibroblasts, dilated endoplasmic reticulum, and vacuoles in fibroblasts were observed in the inner and middle stroma in the LI eyes. Ultimate stress and Young's modulus were lower in the LI eyes compared with those in the control eyes. CONCLUSION: Negative lens application alters eye growth, and results in axial elongation with changes in scleral ultrastructural and mechanical properties.

The effects of monochromatic illumination on early eye development in rhesus monkeys.

PURPOSE: Influence of longitudinal chromatic aberration (LCA) on emmetropization during early eye development has not been studied in primates. We investigated the effects of quasi-monochromatic lighting on refractive development and eye growth in rhesus monkeys. METHODS: Infant rhesus monkeys were raised under one of three lighting conditions for 51 weeks: quasi-monochromatic blue light (peak 455 nm), red light (peak 610 nm), and white light (color temperature 5000 K). All animals underwent biometric measurements using cycloplegic streak retinoscope, keratometry, and A-scan ultrasonography for refraction, corneal power, and axial components, respectively, at designated time points. RESULTS: At the 51st week, the mean difference in refraction of the white light and blue light groups, compared with that of the red light group, reached 1.71 diopters (D) and 1.43 D, respectively (both P < 0.001). Two monkeys in the red light group developed myopia at the 16th week, whereas the other seven remained hyperopic throughout the experiment. No significant difference in mean refraction was observed between the blue light group and white light group. CONCLUSIONS: Illumination from long-wavelength light during early life could be a risk factor for the development of myopia in a small proportion of rhesus monkeys that are sensitive to L-cone stimulation.

Inhibition of corneal fibrosis by Smad7 in rats after photorefractive keratectomy.

BACKGROUND: 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 ß (TGFß). Smad7, an inhibitory Smad, can inhibit TGFß 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. METHODS: 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 TGFß/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). RESULTS: Lentivirus-mediated exogenous Smad7 gene expression in rat corneal tissue resulted in reduced activation of TGFß/Smad signaling caused by downregulation of phosphorylation of Smad2. Smad7 also downregulated the expression of TGFß2. Markers of cell proliferation and fibrosis, including Ki67, α-SMA, and collagen III, were inhibited by Smad7 up to 3 months after PRK operation. CONCLUSION: Smad7 gene transfer inhibits fibrogenic responses of cornea in rats after PRK.

Expression of Smad7 inhibits fibrogenic responses of keratocytes to transforming growth factor ß2.

BACKGROUND: Transforming growth factor ß (TGFß) is one of the most important growth factors in the development of fibrosis and scarring on cornea. Smad7, an inhibitory Smad, can inhibit TGFß 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 ß2 in vitro. METHODS: 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 TGFß2, keratocytes were processed for immunoblotting to assess the phosphorylation of Smad2 as down-stream event of TGFß/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. RESULTS: The Smad7 gene transfer suppressed TGFß/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 TGFß exposed keratocytes. Consequently, the rate of cell proliferation was attenuated. CONCLUSION: Smad7 gene transfer inhibited fibrogenic responses of keratocytes to TGFß2.

Effects of different monochromatic lights on refractive development and eye growth in guinea pigs.

We investigated whether different monochromatic lights with similar luminance or identical light quantum number produce predictable changes in refractive state and eye growth in early eye development in guinea pigs. In experiment I, three groups of guinea pigs (two weeks of age, n=18 in each group) were reared for 12 weeks under LED lighting of 430 nm (short-wavelength light, SL), 530 nm (middle-wavelength light, ML), and broad-band light (BL). The lighting conditions were set to provide equal levels of luminance. All animals underwent refraction and biometric measurements every 2 weeks. In experiment II, the lighting conditions were set at equal quantum number and another three groups of guinea pigs were raised and tested for 20 weeks. In experiment I, compared to the BL group, refraction of the ML group was less hyperopic (P<0.001) with a faster vitreous extension (P<0.001), while the SL group was more hyperopic with a slower vitreous elongation (P<0.001). The mean difference in refraction between the SL and ML groups reached about 4.5 D at maximum. The refractive changes and eye growth in experiment II were very similar to experiment I during the first 12 weeks, but the difference in refraction between the SL and ML groups reached 6.05 D after 20 weeks of treatment, which was greater than the longitudinal chromatic aberration (approximately 1.5 D) in the guinea pigs eyes. The results suggest that the guinea pigs' eyes overcompensated in response to narrow-band light, which resulted in an exaggerated and inaccurate refractive growth.

Expressions of cellular retinoic acid binding proteins I and retinoic acid receptor-ß in the guinea pig eyes with experimental myopia.

AIM: All-trans retinoic acid (RA) is the only extrinsic biochemical candidate known to date that could act as a growth controller, the aim of this study was to investigate the expression cellular retinoic acid binding proteins I (CRABP-I) and retinoic acid receptor-ß (RAR-ß) in retina of the guinea pig eyes with experimental myopia. METHODS: Ninety guinea pigs aged 14 days were equally and randomly divided into three groups: form deprivation (FD), -5D lens, and control. The diffusers for FD were white translucent hemispheres, and -5D lenses were used to introduce hyperopic defocus. Refraction was measured with streak retinoscopy after cycloplegia, and axial length was calculated with Cinescan A/B ultrasonography. Retina harvested at different time points were used to measure RA level with HPLC and expressions of cellular retinoic acid binding proteins I (CRABP-I) and RA receptor-ß (RAR-ß) were assayed with Western blot and Real-time PCR. SPSS13.0 software was used for statistical analysis. RESULTS: Up-regulations of CRABP-I and RAR-ß in ocular tissues correlated with changes in the refractive status and growth rate of the guinea pig eye (P<0.05). 14 days of monocular form-deprivation led to -5.14D myopia and a 0.281mm axial elongation; 14 days of monocular defocus produced -3.64D myopia and a 0.163 mm axial elongation. The level of retinal RA started to elevate in 7 days (P<0.05) after visual manipulation in both FD and -5D lens groups and became more prominent by 14 days (P<0.01) . The expressions of CRABP-I and RAR-ß increased by 14 days after visual manipulation (P<0.05), the mRNA level of RAR-ß, however, increased by 7 days after visual manipulation (P<0.05), which suggested that changes of expressions of CRABP-I and RAR-ß might lag behind the change of RA. CONCLUSION: The levels of CRABP-I and RAR-ß were elevated in retina of the guinea pig eye with experimental myopia. During the progression of experimental myopia, the retinal RA level increased rapidly, and there might be a positive feedback between the increase of RA and up-regulation of RAR-ß.

Clinic study on silicone hydrogel contact lenses used as bandage contact lenses after LASEK surgery.

AIM: To compare the clinical performance of two types of silicon hydrogel contact lenses used as bandage lenses after LASEK surgery. METHODS: A prospective, double-masked study was conducted on 42 eyes of 21 patients who received binocular LASEK surgeries. The interocular difference in spherical equivalent power was less than -1.50D. Patients were randomly assigned to wear Galyfilcon A (Lens A) bandage contact lens in one eye and Balafilcon A (Lens B) in the fellow eye after the surgery. The responses to a subjective questionnaire on comfort of wearing, corneal epithelial status, conjunctival hyperemia, limbal neovascularization, lens fitting and contact lens debris were assessed 1 and 5 days postoperatively. Corneal endothelium was assessed before and 5 days after the surgery upon bandage lens removal. RESULTS: There was no difference between the two groups in terms of conjunctival hyperemia, limbal neovascularization, contact lens fitting, corneal epithelial status, corneal endothelium cell density (CD) and endothelium cell size (CS) at any postoperative visit. Complaints of discomfort, including foreign body sensation, pain and intolerance were statistically more among Lens B wearers at any postoperative visit (P<0.05). Lens B appeared to attract much more debris than Lens A at the 5-day post-operative follow-up visit (P<0.01). CONCLUSION: The two types of silicon hydrogel lenses investigated in this study demonstrated similar clinical performance in terms of corneal responses and lens fitting. However, Lens A showed a better performance in terms of comfort of wearing and deposit resistance.

[Research on retinoic acid signals in retina of guinea pig eyes with different monochromatic illumination].

OBJECTIVE: Retinoic acid (RA) is the only extrinsic biochemical candidate that could act as a growth controller, the present study was designed to evaluate the retinoic acid signals in retina of guinea pig eyes with different monochromatic illumination. METHODS: Ninety 2-week-old guinea pigs were divided into 3 groups randomly and were raised under green (530 nm) (n = 30), blue (430 nm) (n = 30) or white lighting (5000K) (n = 30) conditions. The axial length was measured with Cine scan A/B ultrasonography before, 2 weeks, 4 weeks, 8 weeks during experiment. After the biometrical measurement finished, 9 guinea pigs were sacrificed randomly in each group and retina was dissected. The RA level in retina was detected by High Performance Liquid Chromatography (HPLC). The expressions of retinoic acid-binding proteins I (CRABP-I) and retinoic acid receptor-ß (RAR-ß) protein and mRNA were assayed by Western-blot and Real-time PCR, respectively. The experiment and use of animals followed the Standard of Association for Research in Vision and Ophthalmology. RESULTS: 1. The axial length among the three groups showed a significant difference at 4 weeks during experiment (F = 3.946; P < 0.05), the green lighting group showed the fastest growing, the axial length of the three groups are (8.36 ± 0.11) mm (green), (7.88 ± 0.49) mm (blue), 7.98 ± 0.32 mm (white) respectively at 8 weeks during experiment; 2. The RA levels demonstrated a same trend with the axial length, at 8 weeks during experiment the RA levels are 4.846 ± 0.56 µg/g (green), 3.583 ± 0.26 µg/g (blue), 4.419 ± 0.36 µg/g (white) respectively; 3. Changes of the expression of CRABP-I and RAR-ß occurred at different times, a significant difference of RAR-ß among three groups appeared earlier, the green lighting group showed a highest level. CONCLUSION: The different levels of retinoic acid signals were showed in retina of guinea pig eyes under different monochromatic illumination. The eye growth was significantly faster in green group than in blue group and white group, meanwhile, the RA level, the expressions of CRABP-I and RAR-ß in the retina were higher in green group than the other two groups. These findings suggest that RA may act as a messenger in eye growth promoted by different monochromatic illumination.

[The clinical efficacy and safety study of Esculin and Digitalis glycosides Eye Drops in treating ametropic asthenopia].

OBJECTIVE: To study the clinical efficacy and safety of the Esculin and Digitalis glycosides Eye Drops used in the patients of ametropic asthenopia. METHODS: Multicenter clinical trial. Asthenopia patients were chosen from eleven hospitals cross China from July, 2008 to January, 2009. The experiment was conducted asthenopia patients who used the Esculin and Digitalis glycosides Eye Drops for 4 weeks continuously. Symptoms of asthenopia, UCVA (uncorrected vision acuity), refraction, amplitude of accommodation, accommodative lag, accommodative sensitivity and positive/negative relative accommodation were measured at different time points, such as treated before, 1 week and 4 week in treated after. RESULTS: After the 4-week's use of Esculin and Digitalis glycosides Eye Drops, each subjective symptom of the patients was decreased significantly (F=353.30, P<0.05). In addition, most of the objective exams of accommodation ability were significantly improved, such as UCVA (left eye: F=23.39, P<0.05; right eye: F=15.62, P<0.05), refraction (left eye: F=10.34, P<0.05; right eye: F=17.13, P<0.05), amplitude of accommodation (left eye: F=14.46, P<0.05; right eye: F=8.29, P<0.05; eyes: F=13.86, P<0.05), accommodative lag (F=14.89, P<0.05) and accommodative sensitivity (left eye: F=62.67, P<0.05; right eye: F=68.77, P<0.05; eyes: F=82.74, P<0.05). And no patient appeared any adverse reaction in whole experiment. CONCLUSIONS: Esculin and Digitalis glycosides Eye Drops is effective and safety for use in the patients of ametropia asthenopia.

[Refraction is important procedure in the diagnose and treatment of eye diseases].

Refraction is the primary and necessary work in the diagnose of eye diseases. It is also the useful methods which can be used in the treatment of eye diseases. High attention should be paid on refraction in daily clinical work, including talents training, necessary equipment and standard refraction process.

[A compare study on cornea biomechanical properties in normal and keratoconic eyes].

OBJECTIVE: To compare the corneal hysteresis (CH) and corneal resistance factor (CRF) measured with the Ocular Response Analyzer (ORA) in normal and keratoconic eyes. METHODS: It was a case-control study. Random selected 96 normal eyes and 46 keratoconic eyes in the same period were included in this study. Normal eyes were divided into 2 groups: high corneal astigmatism (> or = 3.00 D) and low-to-moderate corneal astigmatism (< 3.00 D). Keratoconic eyes were also divided into 3 groups based on Amsler-Krumeich classification: mild (stage I), moderate (stage II) and severe (stage III/IV). CH and CRF were compared between groups and the areas under ROC curves of the CH and CRF were calculated. RESULTS: The mean CH and CRF were (7.1 +/- 1.6) mm Hg and (6.3 +/- 1.5) mm Hg in keratoconic eyes compared with (10.1 +/- 1.3) mm Hg and (10.5 +/- 1.6) mm Hg in normal eyes. The difference were statistically significant(t = -11.813, -14.943; P < 0.001). In normal eyes, there was no difference of CH or CRF between the high corneal astigmatism and low-to-moderate corneal astigmatism (t = 0.373, 0.095; P > 0.05). In keratoconic eyes, there was a significant negative correlation between CH and the keratoconus grade (r = -0.627, P < 0.001) and the same relationship was found between CRF and the keratoconus grade (r = -0.587, P < 0.001). In multiple linear regression analysis,CH was correlated with central corneal thickness (CCT) and corneal curvature (r = 0.320, -0.375; P < 0.05) and CRF was correlated with corneal curvature in keratoconic eyes (r = -0.441, P < 0.01) , while they were only correlated with CCT in normal eyes (r = 0.367, 0.459; P < 0.001). The areas under ROC curves of the CH and CRF were 0.9282 and 0.9731 (Z = 20.462, 38.305; P < 0.0001), the difference between them was significant (Z = 7.134, P = 0.008). CONCLUSIONS: The CH and CRF were significantly lower in keratoconic eyes than in normal eyes, especially on CRF. The long-term follow-up of CH and CRF may provide information for evaluation of progression of keratoconus. They may be included as indicators for detecting keratoconus.

[Setting the individual file of ocular refractive development of children is the primary procedure in the prevention of myopia].

The purpose of setting the file of ocular refractive development is to record the process of eye development in children with plan. Set the individual file and begins at 3 years old till 12. Examination is done every 6 months. Parameters are recorded including power of cycloplegic refraction, visual acuity, keratometer, anterior chamber depth, axial length, intraocular pressure, body height and weight. In this way, can provide very important information as to the prompt intervening in myopia control. It is also the effective and practical way in myopia prevention.

A generic eye model by reverse building based on Chinese population.

The human eye has ethnic difference, the existing typical eye models are based on western eyes. A generic eye model based on Chinese population is presented for the first time. The statistical analyzed ocular parameters based on measured data are used for the initial generic eye model, and the wavefront aberration data obtained at two different pupil diameters are used for reproduction by optimizing the initial generic eye model. The differences and similarities between Chinese generic eye model and western eye models are given. The Chinese generic eye model provides a suitable model for the related further researches and applications on Chinese eye.

Incidence of myopia in high school students with and without red-green color vision deficiency.

PURPOSE: To investigate the influence of color vision on myopia development by testing refraction error and axial length of the eye for high school students with and without color vision deficiency (CVD). METHODS: A school-based cross-sectional, cluster sample study was conducted to test the color vision and refractive error of 16,539 high school students. Students were screened for CVD using a pseudoisochromatic plate. CVD was confirmed in students failing the test using a Farnsworth-Munsell 100-Hue Test which also served to classify the subtype (protan or deutan). Three classmates of each CVD subject, matched in five myopia risk factors, were chosen to form the normal color vision (CN) control group. Ophthalmic examinations were performed to determine refractive status and axial length. RESULTS: Of the students, 309 were found to have red-green CVD and 927 were selected as the CN control group. The prevalence of myopia in the CVD group (45.6%) was significantly lower than that of the CN group (65.8%; P<0.001). The CVD group was also less myopic in refraction (P<0.001) than CN, and protan subjects had shorter axial lengths than those in the control group (P=0.007). CONCLUSIONS: Color vision deficiencies appear to influence the development of myopia. The observed lower incidence of myopia in people with CVD may be linked to the reduced functionality of the L/M chromatic mechanism.

[The effect of the flap thickness on forward shift of posterior corneal surface in excimer laser surgery correcting high myopia].

OBJECTIVE: To investigate the influence of flap thickness of laser in situ keratomileusis (LASIK) and subepithelial keratomileusis on the forward shift of the posterior corneal surface in high myopia METHODS: It was a case-control study. In this study, 151 right high myopic eyes of patients [spherical equivalent range - 6.00 to - 10.00 diopter, 46 subepithelial keratomileusis eyes (epithelial sheet group), 64 LASIK eyes with 110 microm flap thickness (thin flap group) and 41 LASIK eyes with 130 microm flap thickness (normal flap group)] were evaluated preoperatively and postoperatively with the Pentacam to determine the shape change in the posterior corneal surface. Changes in posterior shape were calculated by comparing refraction and elevation of posterior corneal surface in the part corresponding to the pupil center preoperatively and postoperatively. RESULTS: The mean estimated residual bed thickness (RBT) of epithelial sheet eyes, thin flap eyes and normal flap eyes was (362 +/- 23), (320 +/- 25) and (300 +/- 21) microm, respectively. The RBT difference between epithelial sheet group and thin or normal flap group was statically significant (F = 85.685, P <0.001) and the difference between 2 LASIK groups was also significant (P < 0.05). There was no significant difference between three groups in ablation depth (P > 0.05). The mean posterior corneal refraction and elevation change of epithelial sheet eyes, thin flap eyes and normal flap eyes in the pupil center was (-0.12 +/- 0.14)D and (0.9 +/-1.8) microm, ( -0.20 +/- 0.22)D and (1.3 +/- 1.6) microm, (-0.21 +/- 0.18)D and (1.5 +/- 1.5) microm, respectively. A significant correlation between posterior elevation and refraction change was present in all 3 groups. The amount of posterior corneal elevation change correlated significantly with the ablation depth in thin flap group and normal flap group (r = 0.265, 0.311; P <0.05). CONCLUSION: In treating high myopia, both subepithelial ablation and LASIK surgery induce tiny forward shift of posterior corneal surface when the RBT was thick enough. Deeper ablation or thicker corneal flap may increase the trend of forward shift of posterior corneal surface.

[A study on the expression of opsins in form-deprived myopia retina of guinea pig].

OBJECTIVE: To investigate the expression of cone opsins in form-deprived myopia (FDM) of guinea pig. METHODS: Twenty-eight pigmented guinea pigs aged one-week were randomly divided into two groups: FDM group (n = 14) and control group (n = 14). White translucent vinyl diffuse attached to one randomly selected eye was used to deprive eyes of form-vision in FDM group. RT-PCR and immunohistochemistry were performed to compare the opsin mRNA expression and spatial density of photoreceptor opsin in the ventral, central and dorsal retinal areas of two groups using antibody against short and medium-wave-length-sensitive cone opsin. Slides were viewed using Leica confocal microscope and Leica light microscope. RESULTS: The distribution of opsin across the guinea pig retinae as determined by antibody labeling of cone opsin was asymmetric, with the dorsal retina dominated by M-opsin, and the ventral retinae by S-opsin. But the ventral area also showed positive staining for the M-opsin. Opsin spatial density decreased with increasing retinal eccentricity for both M and S opsins. The spatial density of S-opsin decreased most steeply for eccentricity up to one-third distance from optic disc to retinal edge. The spatial density of M-opsin gradually decreased with eccentricity. The expression of spatial density of M-opsin was higher than that of S-opsin in all three regions. The expression of density of S-opsin in normal control eye is as follow: (805.0 +/- 203.3) mm(-2) (ventral); (100.0 +/- 57.7) mm(-2) (dorsal); (1637.2 +/- 314.1) mm(-2) (Central). FDM eye: (640.9 +/- 196.8) mm(-2) (ventral); (1016.7 +/- 144.6) mm(-2) (central); (70.9 +/- 30.8) mm(-2); where The expression of spatial density of M-opsin in normal control eye are: (946.2 +/- 388.5) mm(-2) (dorsal); (1666.7 +/- 137.8) mm(-2) (central); (175.0 +/- 100.9) mm(-2) (ventral). FDM eye: (1436.7 +/- 366.0) mm(-2) (dorsal); (2780.0 +/- 180.5) mm(-2) (central); (318.2 +/- 172.7) mm(-2) (ventral). The results of RT-PCR examination showed that the relative optical density (OD) value of M-opsin and S-opsin are: 1.06 +/- 0.07 (FDM eye), 0.51 +/- 0.10 (control eye), and 0.70 +/- 0.07 (FDM eye), 1.25 +/- 0.06 (control eye) respectively. The expression of both opsins in FDM eyes was significant differences compared with control (P < 0.05). CONCLUSION: FDM can increase the expression of M-opsin and decrease the S-opsin expression in guinea pig. cone opsins may play a role in the development of myopia.

[Stromal cells change after epipolis laser in situ keratomileusis and laser-assisted subepithelial keratectomy in rabbits].

OBJECTIVE: To compare the effects of epipolis laser in situ keratomileusis (Epi-LASIK) and laser-assisted subepithelial keratectomy (LASEK) on the corneal stromal cells, and to evaluate their effects on corneal haze histopathologically. METHODS: Forty-eight New Zealand white rabbits (96 eyes) were randomly treated with Epi-LASIK in one eye and LASEK in the other, and 2 rabbits (4 eyes) without any treatment were used as control. Cornea stromal cell apoptosis was evaluated by terminal deoxyribonucleotidyl transferase-mediated deoxynuridine triphosphate nick end labeling (TUNEL) assay. Stromal cells proliferation and myofibroblasts generation were evaluated by immunocytochemical analyses the expression of Ki-67 and alpha-smooth muscle actin (alpha-SMA) respectively. Myofibroblast generation was further testified by Western blot analysis of alpha-SMA. Both number of TUNEL, Ki-67 and alpha-SMA positive cells and expression of alpha-SMA were semi quantitatively analyzed to explore their effects on corneal haze. RESULTS: Many TUNEL-positive cells appeared in the central anterior stromal in early stages after both LASEK and Epi-LASIK, and the number of TUNEL-positive cells reached a peak 24 hours after either LASEK or Epi-LASIK. There were more TUNEL positive cells found in LASEK group than that in Epi-LASIK group in 1 week postoperatively (t = 3.63, 7.80, 4.34, 2.95, all P < 0.01). There were a lot of Ki-67-positive cells in anterior corneal stroma after both LASEK and Epi-LASIK, but the peak appeared at 72 hours after the treatments. The significant difference was also found in the number of Ki-67-positive cell between the two treatments in 1 week postoperatively (t = 3.81, 5.85, 5.09, 5.59, all P < 0.01). alpha-SMA-positive cells started to appear apparently at 1 week after both LASEK and Epi-LASIK, and both the peaks appeared at 1 month after the treatments, and there were still a lot of alpha-SMA-positive cells in corneal stroma at 3 months after LASEK. There were more alpha-SMA-positive cells found after 1 week in LASEK group than that in Epi-LASIK group (t = 2.97, 7.19, 6.73, all P < 0.01). CONCLUSION: There are less stromal cell apoptosis, proliferation and myofibroblast generation in Epi-LASIK than that in LASEK. Therefore, comparing with LASEK, Epi-LASIK induces less corneal haze response in correcting myopia.

[Fully apply the optometry knowledge to improve the visual quality of Chinese people].

With the rapid development of modern ophthalmology and optometry, people put in higher claim for visual quality. However, the application and penetration of the optometry knowledge and research achievement in every domain of ophthalmology are bound to affect the elevation of visual quality, which is one of the highlights our future work.

[Take high of the study of VDT related eye symptoms].

The characteristics of visual display terminal (VDT) and related eye symptoms were analyzed. Research of the effect of VDT on visual function, visual development and characteristics of ocular surface was presented. Currently research still stays in the initial stage. Intensive research of VDT related eye problem will provide effective prevention and treatment methods for clinic work.

[Recovery of corneal sensitivity after laser in situ keratomileusis and laser-assisted subepithelial keratectomy].

OBJECTIVE: To compare the recovery of corneal sensitivity after laser in situ keratomileusis (LASIK) and laser-assisted subepithelial keratectomy (LASEK). METHODS: Central corneal sensitivity (CCS) was measured with a Cochet-Bonnet esthesiometer in 59 patients before and 2 weeks, 1, 3 and 6 months after myopic correction by LASIK or LASEK. Among them, 50 patients were treated with LASEK and 9 patients were treated with LASIK. RESULTS: CCS were reduced in the early period time after LASEK and LASIK, but more reduction was seen after LASIK. At every time points, the CCS after LASEK was better than that after LASIK (at 2 weeks, 1 and 3 months P < 0.01, at 6 months P = 0.031). In myopic eyes with less than 6.00 diopters (D), the CCS recovered at 3 months after LASEK (P > 0.05), but it didn't recover at 6 months after LASIK (P = 0.023). In myopic eye with more than 6.00 D, the recovery of CCS was seen at 6 months after LASEK (P > 0.05). Correlations between CCS and ablation depth were found at 3 and 6 months after LASEK (r = 0.419, 0.433, 0.413; P < 0.05), but no correlation was found after LASIK (P > 0.05). CONCLUSION: Recovery of corneal sensitivity is faster after LASEK than after LASIK. Ablation depth is related to the recovery of corneal sensitivity after LASEK.