Background: Modern laser surgery uses Nd:YAG laser capsulotomy for posterior capsule opacification (PCO) and Nd: YAG laser vitreolysis for symptomatic vitreous floaters (VF). We report a case of acute retinal detachment seven days after Nd:YAG laser capsulotomy combined with Nd:YAG laser vitreolysis and analyze the cause of this complication. Case presentation: A 58-year-old myopic woman complained of decreased visual acuity and symptomatic floaters with her left eye for 3 months. We found she had significant PCO and VF in the posterior vitreous. She underwent neodymium-doped yttrium aluminum (Nd:YAG) laser vitreolysis immediately after Nd:YAG capsulotomy. After 7 days, she complained of rapid vision decline and dark shadows in her treated eye. We found she had a acute severe rhegmentogenous retinal detachment (RD) involving the macula. Then she underwent vitrectomy, retinal reattchment and silicone oil tamponade surgery immediately. Six months later, silicone oil was removed and the best corrected visual acuity (BCVA) of her left eye gradually improved to 10/20 and maintained during a 1-year follow-up period. Conclusion: As myopic patients are at risk of developing retinal detachment, Nd:YAG vitreolysis and capsulotomy should be performed with caution. The laser energy should be as low as possible and careful focus is necessary to reduce interference to the retina.

This paper is concerned with periodic pulse control of Hopf bifurcation for a fractional-order delay predator-prey model incorporating a prey refuge. The existence and uniqueness of a solution for such system is studied. Taking the time delay as the bifurcation parameter, critical values of the time delay for the emergence of Hopf bifurcation are determined. A novel periodic pulse delay feedback controller is introduced into the first equation of an uncontrolled system to successfully control the delay-deduced Hopf bifurcation of such a system. Since the stability theory is not well-developed for nonlinear fractional-order non-autonomous systems with delays, we investigate the periodic pulse control problem of the original system by a semi-analytical and semi-numerical method. Specifically, the stability of the linearized averaging system of the controlled system is first investigated, and then it is shown by numerical simulations that the controlled system has the same stability characteristics as its linearized averaging system. The proposed periodic pulse delay feedback controller has more flexibility than a classical linear delay feedback controller guaranteeing the control effect, due to the fact that the pulse width in each control period can be flexibly selected.

<abstract><p>Hadamard fractional calculus is one of the most important fractional calculus theories. Compared with a single Hadamard fractional order equation, Hadamard fractional differential equations have a more complex structure and a wide range of applications. It is difficult and challenging to study the dynamic behavior of Hadamard fractional differential equations. This manuscript mainly deals with the boundary value problem (BVP) of a nonlinear coupled Hadamard fractional system involving fractional derivative impulses. By applying nonlinear alternative of Leray-Schauder, we find some new conditions for the existence of solutions to this nonlinear coupled Hadamard fractional system. Our findings reveal that the impulsive function and its impulsive point have a great influence on the existence of the solution. As an application, we discuss an interesting example to verify the correctness and validity of our results.</p></abstract>