The application and progression of CRISPR/Cas9 technology in ophthalmological diseases.

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated nuclease (Cas) system is an adaptive immune defence system that has gradually evolved in bacteria and archaea to combat invading viruses and exogenous DNA. Advances in technology have enabled researchers to enhance their understanding of the immune process in vivo and its potential for use in genome editing. Thus far, applications of CRISPR/Cas9 genome editing technology in ophthalmology have included gene therapy for corneal dystrophy, glaucoma, congenital cataract, Leber's congenital amaurosis, retinitis pigmentosa, Usher syndrome, fundus neovascular disease, proliferative vitreoretinopathy, retinoblastoma and other eye diseases. Additionally, the combination of CRISPR/Cas9 genome editing technology with adeno-associated virus vector and inducible pluripotent stem cells provides further therapeutic avenues for the treatment of eye diseases. Nonetheless, many challenges remain in the development of clinically feasible retinal genome editing therapy. This review discusses the development, as well as mechanism of CRISPR/Cas9 and its applications and challenges in gene therapy for eye diseases.

Management of Vasoproliferative Tumors of the Retina with Macular Complications by Pars Plana Vitrectomy Combined with Episcleral Cryotherapy.

OBJECTIVE: To evaluate the efficacy of pars plana vitrectomy (PPV) combined with episcleral cryotherapy in treating vasoproliferative tumors of the retina (VPTR) with macular complications. METHODS: In this retrospective noncomparative interventional case-series analysis, we included 11 eyes of ten patients diagnosed with VPTR. All patients underwent comprehensive ophthalmic examinations and were treated with PPV combined with episcleral cryotherapy. Best-corrected visual acuity (BCVA), tumor activity, retinal morphological structure, and postoperative complications were evaluated. RESULTS: Macular complications included epimacular membrane (n = 10), macular hole (n = 3), and macular edema (n = 1). Tumors were treated with triple freeze-thaw episcleral cryotherapy during PPV. The mean logarithm of minimal angle of resolution (logMAR) BCVA dropped from 0.62 ± 0.58 to 0.39 ± 0.46. The difference between the mean values of logMAR BCVA before and after treatment was statistically significant (t = 2.48, P=0.033). The tumor activity was controlled effectively in nine cases. Compared with preoperative tumor activity, tumor activity after treatment was significantly lower (P < 0.01). The increase of central retinal thickness and the disruption of retinal layers were associated with macular holes, macular edema, and retinal proliferative membrane. After the treatment, visual acuity improved in 91% of the cases, and 73% had no long-term complications. CONCLUSION: PPV combined with episcleral cryotherapy promoted tumor regression, preserved retinal integrity, and improved visual acuity. Thus, the combination of PPV with episcleral cryotherapy can be considered effective and safe for the management of VPTR with macular complications.