Expression and role of specificity protein 1 in the sclera remodeling of experimental myopia in guinea pigs

AIM：To study the expression of collagen I and transcription factor specificity protein 1（Sp1）,a transforming growth factor-β1（TGF-β1） downstream target,and reveal the impact of the TGF-β1-Sp1 signaling pathway on collagen remodeling in myopic sclera.METHODS：Seventy-five 1-week-old guinea pigs were randomly divided into normal control,form deprivation myopia（FDM）,and self-control groups.FDM was induced for different times using coverage with translucent latex balloons and FDM recovery was performed for 1wk after 4wk treatment;then,changes in refractive power and axial length were measured.Immunohistochemistry and reverse transcription-polymerase chain reaction were used to evaluate dynamic changes in collagen I and Sp1 expression in the sclera of guinea pigs with emmetropia and experimental myopia,and the relationship between collagen I and Sp1 levels was analyzed.RESULTS：In the FDM group,the refractive power was gradually changed（from 2.09±0.30 D at week 0 to-1.23±0.69 D,-4.17±0.59 D,-7.07±0.56 D,and-4.30±0.58 D at weeks 2,4,6,and 1wk after 4wk,respectively;P〈0.05）,indicating deepening of myopia.The axial length was increased（from 5.92±0.39 mm at week 0 to 6.62±0.36 mm,7.30±0.34 mm,7.99±0.32 mm,and 7.41±0.36 mm at weeks 2,4,6,and 1wk after 4wk;P〈0.05）.The m RNA and protein expression of Sp1 and collagen I in the sclera of the FDM group was lower than that of the control groups（P〈0.05）,and the reduction was eye-coverage time-dependent.Furthermore,correlation between Sp1 and collagen I down-regulation in the myopic sclera was observed.CONCLUSION：Our data indicate that transcription factor Sp1 may be involved in the regulation of type I collagensynthesis/degradation during myopic sclera remodeling,suggesting that TGF-β1 signaling plays a role in the development and progression of myopia.

Effects of scleral encircling surgery on vitreous cavity length and diopter

AIM： To observe the changes of vitreous cavity length and diopter after scleral encircling（SE） produce.·METHODS： This prospective study included 68 eyes of68 non-consecutive patients with macula-off retinal detachment who were operated by SE surgery. The corneal refractive power, ocular axial length and diopter were measured by keratometer, A-mode ultrasonic meter and computed dioptometer.· RESULTS： There was no significant difference in corneal refractive power among preoperative and post operative 1, 3 and 6mo（0.57±0.54 D at pre-surgery; 0.72±0.26 D at 1mo; 0.71 ±0.34 D at 3mo; 0.69 ±0.31 D at 6mo;all P 〉0.05）. Axial lengths were obviously lengthened,especially in vitreous cavity length（17.87 ±3.09 mm,19.69 ±3.12 mm, 18.97 ±3.56 mm, 18.76 ±3.47 mm, 18.68 ±3.42 mm at pre-surgery, 1wk, 1, 3 and 6mo postoperatively,P 〈0.05） and diopter also increased at beginning and then recovered gradually. After 1 and 3 mo, axial length（vitreous cavity length） and myopia were more and in higher degree than before surgery.·CONCLUSION： The change of postoperative vitreous cavity length is the main factor that results in the changes of axial length and then makes the change of diopter.