Investigation of the efficiency of intrastromal ring segments with cross-linking using different sequence and timing for keratoconus

· AIM: To evaluate and compare the efficacy and stability of intrastromal corneal ring segment(ICRs)implantation with cross-linking(CXL) using different sequence and timing.· METHODS: In this single retrospective study, 86 keratoconic eyes subjected the ICRs implantation. We analyzed only 41 eyes that had complete follow-ups.They were divided into three groups: ICRs implantation was applied only(group normal), ICRs first followed by CXL immediately(group CXL-S), CXL first followed by ICRs long after(group CXL-B). The visual acuity,refractive results, keratometry were compared preoperatively and 1y postoperatively. Their differences among the three groups were also analyzed.·RESULTS: Group normal comprised 25 eyes, group CXL-S 8 eyes, and group CXL-B 8 eyes. There were improvements in the mean uncorrected distance visual acuity(UDVA) and the mean corrected distance visual acuity(CDVA) compared preoperatively and 1y postoperatively [UDVA: 0.31(P =0.030) logarithmic minimum angle of resolution(log MAR) group normal, 0.4(P =0.020) group CXL-S, 0.45(P =0.001) group CXL-B;CDVA : 0. 21 log MAR( P = 0. 013) group normal, 0. 30(P =0.036) group CXL-S; 0.26(P =0.000) group CXL-B].The refractive and topographic outcomes also showed improvements. In terms of comparisons among the three groups, all the P values were above 0.05, showing no significant difference. But only group CXL-B had improvement in UDVA and CDVA for all the patients.·CONCLUSION: With safety and good visual outcomes,ICRs implantation is a viable alternative for keratoconus.No significant difference was found among these three groups.

The association between matrix metalloprotease-9 gene polymorphisms and primary angle-closure glaucoma in a Chinese Han population

AIM:To examine the association between the single nucleotide polymorphisms (SNPs)of matrix metalloprotease-9 (MMP-9) gene and primary angleclosure glaucoma(PACG)in a Chinese Han population.METHODS:DNA samples were extracted from peripheral-blood mononuclear cells of 214 PACG patients and 224 healthy controls.Genotyping of rs3918249,rs3918254,rs17577 and rs3787268 in MMP-9was performed using polymerase chain reaction restriction fragment length polymorphism(PCR-RFLP)analysis and the direct sequencing technique.The association between these genetic polymorphisms and risk of PACG was estimated by χ2 test.RESULTS:The distributions of rs3918249,rs3918254,rs17577 and rs3787268 genotypes among cases and healthy controls were compatible with that from HardyWeinberg equilibrium(HWE,P】0.05).The increased frequency of CC and CT genotypes of rs3918254 were observed in PACG patients compared to healthy controls[P=0.006,P corrected(Pcorr)=0.048].The haplotype analysis showed that the CCGG haplotype was nominal associated with PACG(P=0.015),however,the significant was lost when the Bonferroni correction was used(Pcorr=0.105).CONCLUSION:Our results revealed that rs3918254 in MMP-9 may be a susceptible locus to PACG in China,people with the CC and CT genotypes of rs3918254 are more susceptible to PACG.The susceptibility to PACG inChinese Han patients may be not influenced by SNPs rs3918249,rs3787268 and rs17577 in MMP-9.