Non-contact wide-field viewing system-assisted scleral buckling surgery for retinal detachment in silicone oilfilled eyes

AIM:To evaluate scleral buckling(SB)surgery using a noncontact wide-field viewing system and 23-gauge intraocular illumination for the treatment of rhegmatogenous retinal detachment in silicone oil(SO)-filled eyes.METHODS:Totally 9 patients(9 eyes)with retinal detachment in SO-filled eyes were retrospectively analyzed.All patients underwent non-contact wide-field viewing system-assisted buckling surgery with 23-gauge intraocular illumination.SO was removed at an appropriate time based on recovery.The patients were followed up for at least 3mo after SO removal.Retinal reattachment,complications,visual acuity and intraocular pressure(IOP)before and after surgery were observed.RESULTS:Patients were followed up for a mean of 8.22mo(3-22mo)after SO removal.All patients had retinal reattachment.At the final follow-up,visual acuity showed improvement for 8 patients,and no change for 1 patient.The IOP was high in 3 patients before surgery,but it stabilized after treatment;it was not affected in the other patients.None of the patients had infections,hemorrhage,anterior ischemia,or any other complication.CONCLUSION:This new non-contact wide-field viewing system-assisted SB surgery with 23-gauge intraocular illumination is effective and safe for retinal detachment in SO-filled eyes.

Effects of baffie and intraocular pressure on aerosols generated in the noncontact tonometer measurement during COVID-19

AIM: To investigate the effects of baffle and intraocular pressure(IOP) on the aerosols generated in the noncontact tonometer(NCT) measurement and provide recommendations for the standardized use of the NCT during coronavirus disease 2019(COVID-19). METHODS: This clinical trial included 252 subjects(312 eyes) in The Eye Hospital, Wenzhou Medical University from March 7, 2020, to March 28, 2020. Sixty subjects(120 eyes) with normal IOP were divided into two groups. One group used an NCT without a baffle, another group used an NCT with a baffle. Another 192 subjects(192 eyes) were divided into four groups: Group A;(without a baffle+normal IOP), Group A;(without a baffle+high IOP), Group B;(with a baffle+normal IOP) and Group B;(with a baffle+high IOP). Particulate matter(PM) 2.5 and PM10 generated by all subjects were quantified during the NCT measurement. The IOP values were recorded simultaneously. Effects of baffle and IOP on aerosols generated during the NCT measurement were analyzed.RESULTS: In the normal eye group with a baffle, the aerosol density decreased in a wave-like shape near the NCT with the increase in the number of people measured for IOP, demonstrating no cumulative effect. However, in the normal eye group without a baffle, there was a cumulative effect. PM2.5 and PM10 in Group A;were higher than Group A;(both P<0.001). The PM2.5 and PM10 in Group B;were higher than Group B;(P<0.01, P<0.001 respectively). The PM10 of Group B;was lower than Group A;(P<0.01). PM2.5 in Group B;were lower than Group A;(P<0.01). The median of per capita PM2.5 and PM10 in the combined Group A;+A;were 0.80 and 1.10 μg/m;respectively, which were higher than 0.20 and 0.60 μg/m;in the combined Group B;+B;(both P<0.01). The median of per capita PM2.5 and PM10 in the combined Group A;+B;were 0.10 and 0.20 μg/m;respectively, which were lower than 1.30 and 1.70 μg/m;in the combined Group A;+B;(both P<0.001).CONCLUSION: More aerosols could be generated in patients with high IOP. After the NCT is equipped with a baffle, per capita aerosol density generated decreased significantly near the NCT;And with the increase in the number of people measured for IOP, the aerosols gradually dissipated near the NCT, demonstrating no cumulative effect. Therefore, it is suggested that the NCT should be equipped with a baffle, especially for patients with high IOP.

Characteristics of macular microvasculature before and after idiopathic macular hole surgery

AIM:To evaluate the macular microvasculature before and after surgery for idiopathic macular hole(MH)and the association of preoperative vascular parameters with postoperative recovery of visual acuity and configuration.METHODS:Twenty eyes from 20 patients with idiopathic MH were enrolled.Optical coherence tomography angiography(OCTA)images were obtained before,2 wk,1,and 3 mo after vitrectomy with internal limiting membrane peeling.Preoperative foveal avascular zone(FAZ)area and perimeter and regional vessel density(VD)in both layers were compared according to the 3-month best-corrected visual acuity(BCVA).RESULTS:The BCVA improved from 0.98±0.59(log MAR,Snellen 20/200)preoperatively to 0.30±0.25(Snellen 20/40)at 3 mo postoperatively.The preoperative deep VD was smaller and the FAZ perimeter was larger in the 3-month BCVA<20/32 group(all P<0.05).A significant reduction was observed in FAZ parameters and all VDs 2 wk postoperatively.Except for deep perifoveal VD,all VDs recovered only to their preoperative values.The postoperative FAZ parameters were lower during follow-up.Decreases in preoperative deep VDs were correlated with worse postoperative BCVA(Pearson’s r=-0.667 and-0.619,respectively).A larger FAZ perimeter(Spearman’s r=-0.524)and a lower deep perifoveal VD preoperatively(Pearson’s r=0.486)were associated with lower healing stage.CONCLUSION:The status of the deep vasculature may be an indicator of visual acuity in patients with a closed MH.Except for the deep perifoveal region,VD recovers only to preoperative levels.

Consideration of corneal biomechanics in the diagnosis and management of keratoconus: is it important?

Keratoconus is a bilateral,non-inflammatory,degenerative corneal disease.The occurrence and development of keratoconus is associated with corneal thinning and conical protrusion,which causes irregular astigmatism.With the disruption of the collagen organization,the cornea loses its shape and function resulting in progressive visual degradation.Currently,corneal topography is the most important tool for the diagnosis of keratoconus,which may lead to false negatives among the patient population in the subclinical phase.However,it is now hypothesised that biomechanical destabilisation of the cornea may take place ahead of the topographic evidence of keratoconus,hence possibly assisting with disease diagnosis and management.This article provides a review of the definition,diagnosis,and management strategies for keratoconus based on corneal biomechanics.

Combining robot-assisted surgical system and 3D visualization system for teaching minimally invasive vitreoretinal surgery

AIM:To investigate the feasibility of teaching minimally invasive vitreoretinal surgery with a robot-assisted surgical system and a three-dimensional(3D) visualization system.METHODS:Enucleated porcine eyes were established as an animal model for removing foreign bodies.Forty medical students were recruited to remove foreign bodies to compare the traditional microscope and the 3D system.One junior resident performed the surgical task with manual and robot-assisted operations on 20 porcine eyes for each group.One senior surgeon evaluated the retinal invasion by a graded injury degree.The learning curve for minimally invasive vitreoretinal surgery was described.RESULTS:Compared with the robot-assisted group,the injury degree was higher in the manual group.For the first ten surgeries,the manual and robot-assisted groups had injuries of 2.60±1.35(4 to 0) and 1.80±1.62(4 to 0),respectively.For the last ten surgeries,the injury degrees were 1.90±1.20(3 to 0) and 0.80±0.42(1 to 0).Considering the manual and robot-assisted groups together,95%,75% and 60% of the students considered surgical manipulation with the 3D visualization system to be more comfortable,easier and clearer,respectively.CONCLUSION:The robot-assisted surgical system and 3D visualization system may have value in teaching minimally invasive vitreoretinal surgery.

High intercorneal symmetry in corneal biomechanical metrics

Backgroud:To evaluate the symmetry of corneal biomechanical metrics,measured using an ocular response analyzer(ORA)and self-built corneal inflation test platform,in bilateral rabbit corneas and to investigate their relationship with physical intraocular pressure(IOPp).Methods:Twenty fresh enucleated eyes from ten rabbits were used for ex vivo whole ocular globe inflation.IOP was increased from 7.5 to 37.5 mmHg with 7.5 mmHg steps and biomechanical metrics were acquired using the ORA.At least 3 examinations were performed at each pressure stage.Two biomechanical metrics,corneal hysteresis(CH)and corneal resistance factor(CRF)were recorded and analyzed as a function of IOPp.Corneal specimens were then excised from the intact ocular globe and tested under inflation conditions up to 45.7 mmHg posterior pressure.The experimental pressure-deformation data was analyzed using an inverse modeling procedure to derive the stress-strain behavior of the cornea.Results:A comparison of corneal shape parameters showed no statistically significant difference(P>0.05)between bilateral eyes.Similarly,there were no statistically significant differences in values of CH,CRF and corneal stiffness(as measured by the tangent modulus,Et)between bilateral eyes(CH:F=0.94,P=0.54;CRF:F=4.42,P=0.35;Et:F=3.15,P=0.12)at different pressure levels.IOPp was highly correlated with CRF while the relationship with CH was less pronounced.Conclusions:An obvious interocular symmetry in biomechanical metrics is found in this research.IOP has been shown to have important influences on the value of CRF provided by ORA.