Posterior scleral reinforcement combined with patching therapy for pre-school children with unilateral high myopia.

PURPOSE: Our purpose was to investigate the effect of posterior scleral reinforcement (PSR) combined with patching therapy for pre-school children with unilateral high myopia. METHODS: A total of 32 pre-school children with unilateral high myopia were recruited. They were randomly divided into the PSR and control group, each of which had 16 patients. The patients in the PSR group underwent the simplified PSR surgery followed by rigid gas permeable contact lens wear and traditional patching therapy, while the patients in the control group were only prescribed contact lens wear and patching. Patients were reviewed and the axial length, refraction, best-corrected visual acuity, and stereoscopic vision were respectively examined postoperatively at yearly intervals for three years. RESULTS: The best-corrected visual acuity was significantly higher in the PSR group than that in the control group at any study visit. A statistically significant difference in axial length was found between the PSR group (27.38 ± 1.30 mm) and the control group (28.29 ± 0.74 mm) at the postoperative three-year (p = 0.03) time point. There was a statistical difference in refractive error between the PSR group (-13.13 ± 2.55 D) and the control group (-15.42 ± 1.83 D) at 3-year follow-up. No significant difference was found between the two groups with respect to the stereoscopic vision by the end of follow-up at 3 years (p =0.103). CONCLUSIONS: PSR combined with the patching therapy has the potential to arrest the progression of high myopia and to help the treatment for amblyopia.

Refractive change in the adult rabbit eye after corneal relaxation with the femtosecond laser.

BACKGROUND: A new procedure to correct myopia that does not disturb the cornea in the optical zone and avoids injuring the corneal epithelium could be a key advance in corneal refractive surgery. The aim of this study is to observe the refractive change in the adult rabbits undergoing femtosecond laser-assisted multilayer intrastromal ablation in the mid-periphery of the cornea without injury of epithelium. METHOD: The right eyes of 8 New Zealand White adult rabbits were used for the experiments. A 60-kHz femtosecond laser delivery system was used, and three lamellar layers of laser pulses were focused starting at a corneal depth of 180 µm and ending at 90 µm from the surface, with each successive layer placed 45 µm anterior to the previous layer. In the interface of the applanation contact lens cone, a 6-mm diameter aluminum circle was placed at the center to block the laser, limiting ablation to the mid-periphery of the cornea. The laser settings were as follows: spot/line separation, 10 µm; diameter, 8.0 mm; energy for ablating the stroma, 1.3 µJ. An authorefractor was used to assess the manifest refraction. RESULTS: Mean spherical equivalent (SE) (mean ± SD, SD: standard deviation) was significantly increased at postoperative week 1 (1.67 ± 0.26 D, p < 0.0001), month 1 (1.65 ± 0.23 D, p < 0.0001), and month 3 (1.60 ± 0.22 D, p < 0.0001) compared to baseline (0.68 ± 0.27 D). Mean spherical equivalent showed no significant change between postoperative week 1 and month 3 (p = 0.1168). CONCLUSION: Femtosecond laser-assisted multilayer corneal intrastromal ablation in the mid-periphery may cause a consequent hyperopic shift with no refractive regression.

Transfer from blue light or green light to white light partially reverses changes in ocular refraction and anatomy of developing guinea pigs.

Relative to the broadband white light (BL), postnatal guinea pigs develop myopia in a monochromic middle-wavelength light (ML, 530 nm) environment and develop hyperopia in a monochromic short-wavelength light (SL, 430 nm) environment. We investigated whether transfer from SL or ML to BL leads to recuperation of ocular refraction and anatomy of developing guinea pigs. Two-week-old guinea pigs were given (a) SL for 20 weeks, (b) SL recuperation (SLR, SL for 10 weeks then BL for 10 weeks), (c) ML for 20 weeks, (d) ML recuperation (MLR, ML for 10 weeks then BL for 10 weeks), or (e) BL for 20 weeks. Two weeks after transfer from ML to BL (MLR group), ocular refraction increased from 1.95 ± 0.35 D to 2.58 ± 0.24 D, and vitreous length decreased from 3.48 ± 0.06 mm to 3.41 ± 0.06 mm. Two weeks after transfer from SL to BL (SLR group), ocular refraction decreased from 5.65 ± 0.61 D to 4.33 ± 0.49 D, and vitreous length increased from 3.18 ± 0.07 mm to 3.26 ± 0.11 mm. The MLR and SLR groups had final ocular refractions that were significantly different from those of the ML and SL groups at 20 weeks (ML vs. MLR: p < 0.0001; SL vs. SLR: p < 0.0001) but were still significantly different from the BL group (BL vs. MLR: p = 0.0120; BL vs. SLR: p = 0.0010). These results suggest that recuperation was not complete after return to BL for 10 weeks.

[The progress of fixation eye movement research].

When eyeball fixes targets, it will produce one frequent and regular movement which is difficult to detect. Such movements is called fixation eye motion. This motion can be further divided into drift, tremor and microsaccades. In recent years, research in this field is strikingly increasing. Due to the significant role on the control of fixation positron, maintaining continuous sense of perception, keeping bistable condition, clear vision, spatial orientation and attention, research in this field is maybe a worthwhile myopia research direction.

[Changes of opsin expression in experimental form-deprivation and defocus myopia in guinea pig].

OBJECTIVE: To investigate the opsin expression in form-deprived and defocus myopia in guinea pig and to study the relationship between the opsin expression and the experimental myopia. METHODS: Fifty guinea pigs were randomized into form-deprived group, defocus group (n = 20 in each group) and normal group (n = 10). Guinea pigs in form-deprived group wore a diffuser RGP on one eye since one week after birth. Those in defocus group wore -4.00 D RGP on one eye. The contralateral eyes wore 0 D RGP were used as the control. Refraction, axial length and depth of vitreous cavity were measured after 1 and 2 weeks. Animals were sacrificed and the retina were dissected at 10:00 - 12:00 AM. The level of opsin and its mRNA were measured by Western-blot and real-time PCR, respectively. RESULTS: Two weeks after the experiment, the refraction in form-deprived group and defocus group were (-4.00 ± 0.87) and (-2.00 ± 1.17) D respectively, which were significant different compared with contralateral eyes or normal control group (F = 203.98, 88.66, P < 0.05). These also accompany with increase of axial length and depth of vitreous cavity in form-deprived group and defocus group. Expression of S-opsin mRNA were increased both in form-deprived and defocus groups and the ratios of S-opsin mRNA/ß-actin expression were 0.752 ± 0.05 and 1.117 ± 0.13 in two weeks treatment, which were significant different from contralateral eyes (the ratios of S-opsin mRNA/ß-actin expression were 0.536 ± 0.04 and 0.772 ± 0.10.t = 6.10, 6.28, P < 0.05). Similar findings were also demonstrated in the expression of L-opsin mRNA, which were increased in form-deprived group and defocus group (the ratios of L-opsin mRNA/ß-actin expression were 0.42 ± 0.01) compared with contralateral eyes (the ratios were 0.24 ± 0.0 and 0.34 ± 0.04. t = 6.30, 4.93, P < 0.05) after two weeks experiment. The western-blot results also indicated the high expression of S-opsin and L-opsin level compared to contralateral eyes in form-deprived and defocus groups. CONCLUSIONS: Cone might be the detector receiving the signal of form-deprivation and defocus. Changes of opsin expression might play a role in the occurrence of experimental myopia in guinea pig.

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.

Influence of internal optical astigmatism on the correction of myopic astigmatism by LASIK.

PURPOSE: To investigate the influence of the origin of astigmatism on the correction of myopic astigmatism by LASIK. METHODS: A retrospective study was conducted of the records of 192 patients (192 eyes) undergoing LASIK for correction of myopia and myopic astigmatism from January to September 2010. Ocular residual astigmatism (ORA) and lenticular astigmatism (LA) were determined by vector analysis using objective refraction and Pentacam (Oculus Optikgeräte GmbH) imaging of both corneal surfaces. Patients were divided into two groups according to ORA (high ORA group: ORA/preoperative refractive astigmatism >1; normal ORA group: ORA/preoperative refractive astigmatism ≤ 1) and LA (high LA group: LA/preoperative refractive astigmatism >1; normal LA group: LA/preoperative refractive astigmatism ≤ 1). Procedural efficacy was compared between those eyes with and without a significant amount of internal optical astigmatism using index of success. RESULTS: Mean preoperative vectors for the astigmatism of the anterior cornea, posterior cornea, and lens were -1.33 × 3.0°, -0.33 × 95.3°, and -0.27 × 103.3°, respectively. Mean indices of success in the high and low ORA groups were 1.75 and 0.59, respectively (t=7.81, P<.001). Mean indices of success in the high and low LA groups were 2.07 and 0.70, respectively (t=12.36, P<.001). The higher indices of success in the high ORA and high LA groups suggest a lower efficacy of LASIK in treating astigmatism primarily located intraocularly. CONCLUSIONS: Myopic LASIK is less effective in correcting astigmatism when astigmatism is mainly located at the internal optics. Topography and refractive value should be incorporated in the treatment of patients when a significant amount of internal optical astigmatism is detected preoperatively.

[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.

[Long-term studies on clinical therapeutic efficiency of posterior scleral reinforcement surgery].

OBJECTIVE: To assess the safety and efficiency of posterior scleral reinforcement surgery by analyzing data collected for more than ten years after the surgery. METHODS: Sixteen patients (32 eyes) with high myopia who underwent scleral reinforcement were followed up for more than ten years (10 to 13 years). RESULTS: Best corrected visual acuity was stable (t = 0.26, P > 0.05). The average axial elongation was 0.056 mm per year postoperation after surgery. The ratio of choroidal neovascularization in the operation group was 3.1% (1/32). CONCLUSIONS: Posterior scleral reinforcement is a safe and effective. This procedure can prevent the development of choroidal neovascularization in high myopia. A control study with a larger group of cases as well as related basic is still required.

[Relationship between best corrected visual acuity and refraction parameters in myopia].

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.

[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.

[The expression of Ki-67, TGF-beta(2) and alpha-SMA after the femtosecond laser-assisted intrastromal scanning in rabbit cornea].

OBJECTIVE: To study how the cornea would express Ki-67, TGF-beta(2) and alpha-SMA and how the cornea would heal when it is scanned intrastromally. METHODS: Twenty New Zealand white rabbits were randomly numbered and used for the experiments. The 60 kHz Intralase femtosecond laser delivery system was used to scan 35 rabbit corneas (of these corneas, 5 right corneas were from 5 rabbits). The unoperated 5 left eyes were used as control. The laser settings were: spot/line separation, 10 microm; diameter, 8.5 mm; energy for scanning the stroma, 1.3 microJ; scanning depth, 135 microm, no edge cuts were performed. Slit lamp was used to observe the cornea at 0.5 h, 1 h, 2 h, and 3 months after surgery. On day 1, 3, 7, 30, 90 after surgery, 6 and 1 scanned corneas at each time point were taken for Western blot and immunocytochemical detection respectively to detect the expression of TNF-alpha, Ki-67, TGF-beta(2) and alpha-SMA. RESULTS: Microbubbles were found in corneal stroma after surgery. The number of microbubbles tended to decrease significantly with time. At 2 h, the cornea turned to be transparent again. During 3-month follow-up, the cornea was always transparent and no haze appeared. Western blot analysis and immunocytochemical detection demonstrated that the expression of Ki-67 began to increase at day 1(0.0670 + or - 0.0008) and reached the peak at day 3 after surgery (0.6923 + or - 0.005). While there were significant difference with the control group at day 90 after surgery (t = 24.12, 57.22, 43.26, 39.78, 18.35;P < 0.05), a gradual decrease in expression of ki-67 could be detected from day 3 to 90. There were no significant change in the expression of TGF-beta(2) (t = 0.933, 0.856, 0.934, 0.970, 1.132) and alpha-SMA (t = 1.126, 1.235, 0.993, 1.175, 1.211) at all time points after surgery (P > 0.05). CONCLUSIONS: After intrastromal scanning, the expression of Ki-67 increases and the keratocyte is activated and proliferated. However, due to no epithelium injured and TGF-beta(2) confined to the epithelium, the activated and proliferated keratocytes could not be transformed into myofibroblasts.

[Analysis of flap thickness by anterior segment optical coherence tomography in different flap preparation styles of excimer laser surgery].

OBJECTIVE: To assess and compare the accuracy and regularity and short-term change of corneal flap in different flap preparation styles. METHODS: Eighty eyes of 40 cases were treated with laser-assisted subepithelial keratectomy. One hundred and fifty-five eyes of 78 cases were treated with laser in situ keratomileusis with 90 microm microkeratome flap preparation and eighty-two eyes of 42 cases were treated with laser in situ keratomileusis with 100 microm femtosecond laser flap preparation. Anterior segment optical coherence tomography was used to assess the thickness of epithelial or stromal flaps created with M2 microkeratome or VisuMax femtosecond laser by the same investigator 1 hour, 1 day, 1 week, 1 month and 3 months postoperatively, respectively. The thickness of twenty-five measuring points across each flap in LASIK, which were 1.5 mm, 2.5 mm and 3.5 mm away from vertex of cornea on the horizontal, vertical, 45 degrees and 135 degrees meridian respectively and the vertex of cornea itself, was evaluated. The results were analyzed with t-test or ANOVA by SPSS software. RESULTS: The thickness of epithelial flaps was (57.91 + or - 6.76), (54.94 + or - 4.65), (54.96 + or - 2.70), (55.26 + or - 4.27) and (53.86 + or - 5.56) microm at 1 hour, 1 day, 1 week, 1 month and 3 months respectively, with statistical significant difference between 1 hour and the other time points (F = 20.25, P < 0.05). The average thickness of stromal flaps on the vertex of cornea in microkeratome group was (129.16 + or - 12.10) microm, while (112.69 + or - 5.12) microm in the femtosecond laser group, which means the accuracy of flap preparation with femtosecond laser is better than with microkeratome. The absolute difference between actual and average thickness was (13.16 + or - 4.78) and (5.26 + or - 1.21) microm in the microkeratome group and femtosecond laser group, which means the reproducibility of flap preparation with femtosecond laser is better than with microkeratome as well. Flap morphology showed the feature of thin central area and thick peripheral area in microkeratome flap and uniformity in femtosecond laser flap, which illustrated the better regularity of femtosecond laser flap preparation. CONCLUSIONS: Anterior segment optical coherence tomography is a safe, quick and reliable facility to examine and assess flap morphology. Our results showed the accuracy and regularity of femtosecond laser flap preparation outweighed microkeratome flap preparation.

[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.

[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.

[The effects on corneal wound healing of LASIK with ultra-thin corneal flaps and LASEK in rabbits].

OBJECTIVE: To evaluate the corneal wound-healing response of LASIK with ultra-thin corneal flaps and LASEK in rabbits. METHODS: It was an experimental study. Thirty-two adult New Zealand rabbits were divided into 2 groups with 16 each. Two surgical procedures, LASIK with ultra-thin corneal flaps and LASEK were performed on the right eye of each group, with the left eye as control. A myopic ablation of 10 diopters was performed in each group. Corneal wound-healing and histopathological changes of the ablation zone were studied through slit lamp, light microscope and transmission electronic microscope. The expression levels of collagen I , collagen III, fibronectin (FN) and transforming growth factor beta-1 (TGF-beta1) were investigated by immunohistochemistry and RT-PCR assays. RESULTS: In the group of LASIK with ultra-thin corneal flaps, the corneas were clear without haze followed by slight wound healing and fast recovery. While in the group of LASEK, corneal wound healing was obviously delayed. There was haze in grade 1 (62.5%) and grade 2 (37.5%) in 1 month, with grade 0.5 (43.75%) and grade 1 (56.25%) in 3 months. 1 month and 3 months after surgery, proteins and mRNA of collagen III, FN and TGF-beta1 were expressed in the anterior corneal stromal layer in each group. But the expression was much higher in the group of LASEK (t = 18.47, 11.98, P < 0.05). The protein and mRNA expression of collagen I had no difference between the two groups (t = 0.72, 0.36, 0.47, 2.38, P > 0. 05). The mRNA expression of collagen I, collagen III, FN and TGF-beta1 had no statistical difference between the groups of control and LASIK with ultra-thin flap in 3 months (t = 2.42, 1.54, -0.83, P > 0.05). CONCLUSION: According to the animal experiments, it was suggested that the corneal wound-healing response of LASIK with ultra-thin corneal flaps was much better than that of LASEK.

[Clinical study of diffuse lamellar keratitis after laser in situ keratomileusis].

OBJECTIVE: To investigate a new clinical grading scale of diffuse lamellar keratitis (DLK) following laser in situ keratomileusis (LASIK) and to observe the clinic outcomes of eyes treated with corresponding classified therapy. METHODS: It was a prospective case-control study. Eyes that developed DLK after LASIK were diagnosed by a new criterion of clinical grading scale based on both severity and scope of inflammatory cells infiltrations in the corneal interface. Dose and frequency of topical or systemic corticosteroid were determined by the classified profiles according to each grade. Clinical symptoms, corneal inflammatory cells infiltrations, visual acuity, refractive error and intraocular pressure (IOP) were evaluated on 1, 3, 5, 7, 10 days and 1 month after diagnosis as well as at the time of diagnosis. RESULTS: Among the 35 eyes of 29 patients that developed DLK, mild inflammatory cells infiltrations were mostly seen. Thirty eyes had degree I DLK and 3 had degree II DLK. One eye had degree III DLK and one had degree IV DLK. Inflammatory cells infiltrations in 20 eyes invaded peripheral zone (zone 1) and those in 11 eyes invaded mid-peripheral zone (zone 2). Inflammatory cells infiltrates in 4 eyes invaded central zone (zone 3). Nineteen eyes had degree I zone 1 DLK. Thirty three eyes were diagnosed between the 1st day and the 3rd day after surgery. Uncorrected visual acuity (UCVA) was worse than preoperative best spectacle corrected visual acuity (BSCVA). Inflammatory cells infiltrations retreated within 6.06 2.04 days after classified corticosteroid therapy. One month after the treatment, UCVA had improved to the level of preoperative BSCVA. BSCVA in 30 eyes were equal to or better than those before surgery. Spherical equivalent of the refractive error was (-0.21 +/- 1.16) D. There was no statistic difference in the retreat time of inflammatory cells infiltrations, recovery of visual acuity and refractive error among the different grades of DLK or among the DLK treated with different therapy profiles. No eye suffered from high intraocular pressure during the treatments. CONCLUSIONS: Clinical grading scale and corresponding classified therapy were proved to be effective in the treatment for DLK.

[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.

[Comparison of congenital color vision deficiencies prevalence between Han and Uygur high-school students].

OBJECTIVE: A population-based study was conducted to compare the prevalence of congenital color vision deficiencies (CVD) in high-school students of Uygur and Han nationalities in Xinjiang Uygur autonomous region. METHODS: Students from 7 high schools were examined with pseudoisochromatic color plates and further with Farnsworth Munsell 100 test. The chi-square test was applied to compare categorical variables, and the independent-samples t test was used to compare the measure data. RESULTS: In the study population of 3764 Uygur students, 88 students had CVD, including 69 males and 19 females. 48 of 2055 Han students were diagnosed with CVD, including 46 males and 2 females. No significant difference existed in the prevalence of CVD in boys between two nationalities. The prevalence of CVD in Uygur girls was higher than that in Han girls. CONCLUSIONS: No significant difference was found in the prevalence of CVD in boys between two nationalities. The prevalence of CVD in Uygur girls was higher than that in Han girls.

Effect of flap thickness on higher order wavefront aberrations induced by LASIK: a bilateral study.

PURPOSE: To investigate the effect of flap thickness on wavefront aberrations induced by LASIK. METHODS: LASIK was performed on 56 eyes of 28 patients with refraction errors that were well matched between the right and left eyes. For each patient, a planned 160-microm flap was created for one randomly selected eye using the Moria M2 microkeratome (130-microm head; thick flap group), and a 110-microm flap was created for the contralateral eye with the same microkeratome (90-microm head; thin flap group). Flap thickness was measured using ultrasonic pachymetry. Wavefront aberrations were measured in the anterior cornea using the Orbscan II (Bausch & Lomb) and in the whole eye using the Wavefront Supported Custom Ablation (WASCA) aberrometer (Carl Zeiss Meditec) preoperatively and at 1 month and 1 year postoperatively. RESULTS: Mean flap thickness was 155 +/- 13 microm in the thick flap group and 112 +/- 11 microm in the thin flap group. Mean root-mean-square of higher order wavefront aberrations were changed for the different test times in the cornea (F = 29.9, P < .0001) and the whole eye (F = 48.0, P < .0001). There was no significant difference between the two flap groups for the cornea (F = 0.76) or for the whole eye (F = 0.07). Similar results were observed for higher order Zernike aberrations such as spherical aberration and comas. CONCLUSIONS: The results suggest higher order wavefront aberrations induced by LASIK are independent of flap thickness. Complications in visual outcome for patients with different flap thickness should be attributed to factors other than aberrations.