[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.

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.

Sonic hedgehog expression and its role in form-deprivation myopia in mice.

PURPOSE: To investigate whether sonic hedgehog (Shh) plays a role in postnatal eye development and the development of experimentally induced myopia. METHODS: Expression of Shh, Patched-1 (Ptc-1), and Gli3 was evaluated in the eyes of 13- to 14-day-old C57B/L6 mice with form-deprivation myopia (FDM) (n = 100) and controls (n = 100) using real-time PCR and Western blot analysis. In a second experiment, 336 mice were divided into two groups: the first wore a unilateral translucent diffuser to induce myopia and the second served as a control. Both groups received four intravitreal injections of either Shh-N (Sonic hedgehog amino-terminal peptide) or cyclopamine (a specific inhibitor of the Shh pathway) every other day. Retinoscopic refraction and axial length measurements were performed on the 11th day of form deprivation. Sections of the eyes were observed using a light microscope. RESULTS: Inducing myopia caused a significant increase in expression of Shh mRNA (7 days: t = 6.09, p = 0.004; 14 days: t = 3.48, p = 0.025) and protein (7 days: t = 4.06, p = 0.015; 14 days: t = 4.25, p = 0.013). Expression of both Gli3 mRNA (t = 7.61, p = 0.002) and protein (t = 2.89, p = 0.045) increased after 7 days of occlusion. Administration of Shh-N stimulated the development of myopia and axial growth in both occluded (refraction: F = 7.49, p = 0.001; axial length: F = 9.89, p < 0.001) and non-occluded eyes (refraction: F = 14.20, p < 0.001; axial length: F = 20.37, p < 0.001). Cyclopamine reduced myopic refractive error and axial elongation in occluded eyes (refraction: F = 27.91, p < 0.001; axial length: F = 15.18, p < 0.001). It also influenced non-occluded eyes, reducing axial growth and shifting the refraction toward hyperopia (refraction: F = 14.81, p < 0.001; axial length: F = 3.99, p = 0.024). No difference in retinal thickness was found between experimental and control eyes. CONCLUSIONS: The Shh signaling pathway may influence both form-deprivation myopia and the postnatal growth of eyes with normal visual input.

[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.

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.

[Clinical features of Best vitelliform macular dystrophy].

OBJECTIVE: To investigate the clinical features of Best vitelliform macular dystrophy (BVMD) in Chinese patients. METHODS: Ten consecutive patients (20 eyes) were diagnosed as BVMD by the fundus photography, EOG, fluorescein angiography (FFA) and optical coherence tomography (OCT). Their clinical data were analyzed retrospectively. RESULTS: Of the twenty eyes from ten patients, three eyes from three patients (age range 9-18 years, mean 12.33+/-4.93 years) in Stage II, two eyes from two patients (age range 9-18, mean 13.50+/-6.36 years) in Stage IIa, four eyes from two patients (age range 11-29 years, mean 20.00+/-10.39 years) in Stage III and eleven from six patients (age range 9-44 years, mean 27.09+/-14.02 years) in Stage IV were found at their first presentation to our hospital. OCT scan showed the broadening of the outer-retina-choroid-complex signal with the retinal elevation in Stage II. The moderately reflective material which represents the vitelliform material may accumulate forming a conical mound that would elevate the retinal sensory layer in Stage IIa. In 'pseudohypopon' or atrophy phase there may be a large volume of serous retinal detachment. If a fibrous macular or foveal atrophy was seen in the fundus photograph, the thinning of the outer-retina-choroid-complex signal with serous retinal detachment may be shown by OCT. CONCLUSIONS: The present observation is a first study on the clinical findings of Chinese BVMD patients. It supports the hypothesis that the yellowish material is located under the RPE. Long term evaluation with more patients should be done to acknowledge more characteristics of BVMD in Chinese patients.