Retinal vascular morphological characteristics in diabetic retinopathy: an artificial intelligence study using a transfer learning system to analyze ultra-wide field images.

AIM: To investigate the morphological characteristics of retinal vessels in patients with different severity of diabetic retinopathy (DR) and in patients with or without diabetic macular edema (DME). METHODS: The 239 eyes of DR patients and 100 eyes of healthy individuals were recruited for the study. The severity of DR patients was graded as mild, moderate and severe non-proliferative diabetic retinopathy (NPDR) according to the international clinical diabetic retinopathy (ICDR) disease severity scale classification, and retinal vascular morphology was quantitatively analyzed in ultra-wide field images using RU-net and transfer learning methods. The presence of DME was determined by optical coherence tomography (OCT), and differences in vascular morphological characteristics were compared between patients with and without DME. RESULTS: Retinal vessel segmentation using RU-net and transfer learning system had an accuracy of 99% and a Dice metric of 0.76. Compared with the healthy group, the DR group had smaller vessel angles (33.68±3.01 vs 37.78±1.60), smaller fractal dimension (Df) values (1.33±0.05 vs 1.41±0.03), less vessel density (1.12±0.44 vs 2.09±0.36) and fewer vascular branches (206.1±88.8 vs 396.5±91.3), all P<0.001. As the severity of DR increased, Df values decreased, P=0.031. No significant difference between the DME and non-DME groups were observed in vascular morphological characteristics. CONCLUSION: In this study, an artificial intelligence retinal vessel segmentation system is used with 99% accuracy, thus providing with relatively satisfactory performance in the evaluation of quantitative vascular morphology. DR patients have a tendency of vascular occlusion and dropout. The presence of DME does not compromise the integral retinal vascular pattern.

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

AIM: To evaluate scleral buckling (SB) surgery using a non-contact 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.

Macular density alterations in myopic choroidal neovascularization and the effect of anti-VEGF on it.

AIM: To analyse macular microvascular alterations in myopic choroidal neovascularization (mCNV) and the efficiency of anti-vascular endothelial growth factor (anti-VEGF) therapy for mCNV by optical coherence tomography angiography (OCTA). METHODS: A total of 123 patients were included in this retrospective study, divided into mCNV group, high myopia (HM) group, and normal group at the Affiliated Eye Hospital of Wenzhou Medical University from January 2017 to January 2019. Superficial vessel density, deep capillary density, foveal avascular zone (FAZ) area, A-circularity index (AI) and vessel density around the 300 µm width of the FAZ region density (FD) and the area of choroidal neovascularization (CNV) lesion (only for mCNV group) were measured on 3×3 mm2 OCTA images. FAZ area was corrected for axial length. Central macular thickness (CMT) was measured on OCT in mCNV group. Compared the parameters on OCTA of 3 groups and pre-anti-VEGF and post-anti-VEGF at 1, 2, 3, and 6mo follow-up in mCNV group. RESULTS: There were significant differences among 3 groups in superficial vessel density, deep capillary density and FD (P<0.05). FAZ area in HM group was smaller than normal group (P<0.05), but there was no significant difference between mCNV group and the other two group. AI increased in mCNV group (P<0.05). The mean CMT, area and flow area of CNV lesion decreased after treatment (P<0.05), while vessel density and FAZ didn't change. The mean CMT, area and flow area of CNV lesion statistically decreased after anti-VEGF treatment in mCNV group (P<0.05), while superficial vessel density, deep capillary density and FAZ area, AI and FD didn't change. The mean reduction ratio of lesions was 50.32% (7.07% to 100%). Lesion regression 100% was observed in 2 cases (4.88%). There was a negative correlation between the CNV lesion area and reduction ratio (r=-0.380, P=0.042) and the flow lesion area and reduction ratio (r=-0.402, P=0.030). CONCLUSION: Macular vessel density decreases, FAZ turns smaller and more irregular in mCNV eyes. Anti-VEGF therapy is efficient for mCNV without affecting vessel density and FAZ, but it is unable to completely eliminate CNV lesions in most cases. The bigger mCNV lesions have lower reduction ratio.

A decrease in macular microvascular perfusion after retinal detachment repair with silicone oil.

AIM: To observe whether silicone oil (SO) tamponade could decrease macular perfusion after retinal detachment repair. METHODS: A prospective observational case-control study. Patients diagnosed with primary macular off rhegmatogenous retinal detachment undergoing successful retinal repair surgery with vitrectomy were strictly selected. Optical coherence tomography angiography findings were compared between SO and air tamponade groups. Two postoperative visiting points were set (1 and 3mo). RESULTS: Totally 29 patients (29 eyes) were enrolled. Twenty cases had SO tamponade while 9 cases were with air tamponade. At the first visiting point, superficial parafoveal vessel density (PFSVD) significantly decreased in the SO group (P=0.0403), especially in the superior quadrant or superior-hemi area (P=0.0089, 0.0426, respectively). Parafoveal deep vessel density (PFDVD) had no difference between the two groups. At the second visiting point, all quadrants of PFSVD reduced significantly in the SO group (P=0.0256, 0.0001, 0.0031, <0.0001 in temporal, superior, nasal, and inferior area, respectively), but PFDVD remained no different. In the air group, all areas of PFSVD showed significantly improving from the first visit to the second one (P=0.0324, 0.0001, 0.0371, 0.0026, in temporal, superior, nasal, and inferior area, respectively); however, almost all quadrants of PFDVD showed no changes during this period. In the SO group, both PFSVD and PFDVD showed no obvious changes between the two visiting points. Besides, parafoveal full retinal thickness in the SO group reduced significantly at both visiting points over the air tamponade, while the foveal avascular zone area showed no difference in the two groups. CONCLUSION: After retinal detachment surgery with vitrectomy and SO tamponade, superficial macular perfusion and full retinal thickness could decrease obviously when compared to air tamponade. This reduction process could persist throughout the tamponade period.

Comprehensive evaluation of intravitreal conbercept versus half-dose photodynamic therapy for chronic central serous chorioretinopathy.

AIM: To compare the safety and efficacy of conbercept intravitreal injection and half-dose photodynamic therapy (PDT) in treating chronic central serous chorioretinopathy (CSC). METHODS: This study was retrospective. Thirty-seven patients (37 eyes) with chronic CSC received conbercept injections while 57 patients (57 eyes) were treated with half-dose PDT. All subjects were followed in 6mo. Outcome measures included change in best-corrected visual acuity (BCVA), central macular thickness (CMT), subfoveal choroidal thickness (SFCT), and resolution of subretinal fluid (SRF). RESULTS: There was no adverse event observed in either treatment group. At the 6-month follow-up, 26 eyes (70.3%) in the conbercept group and 54 eyes (94.7%) in the half-dose PDT group (P<0.05) reached full resolution of SRF. The mean logarithm of the minimum angle of resolution (logMAR) BCVA significantly improved (P<0.001) in both treatment groups with better outcome at early phase in the half-dose PDT group (2wk, 1, and 2mo, P<0.05). All subjects experienced significant CMT improvement (P<0.001) with no statistical difference between the two groups (P>0.05). The SFCT also improved in all subjects (P<0.001) with better outcome in the half-dose PDT group (P<0.05). CONCLUSION: Both intravitreal conbercept and half-dose PDT are safe to use in treating chronic CSC. By 6mo, both treatment groups are efficacious in improving BCVA, reducing CMT and SFCT, and resolving SRF in eyes with chronic CSC. Half-dose PDT may show better outcome at initial phase of treatment in chronic CSC. Longer follow-up period is necessary to study for long-term effect and safety.

Comparison of persistent submacular fluid in different preoperative macular status after vitrectomy for rhegmatogenous retinal detachment.

AIM: To compare the incidence of persistent submacular fluid (SMF) and visual outcome after pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment (RRD) in different preoperative macular status according to optical coherence tomography (OCT). METHODS: A non-randomized, retrospective review was performed for patients who underwent successful PPV for RRD. OCT exams were taken preoperatively and 1mo after surgery, until SMF disappeared. According to the preoperative macular status on OCT, patients were divided into two groups: macula-off RRD (Group A) and macula-on RRD (Group B). In Group A, there were two subgroups: macula partly detached (Group A1) and macula totally detached (Group A2). The main outcome measures were the presence of SMF on OCT 1mo after surgery, and the preoperative and postoperative best corrected visual acuities (BCVA), among the different groups and depending on the presence or absence of persistent SMF. RESULTS: A total of 139 eyes of 139 patients were included in the study. Persistent SMF at 1mo after surgery was 15.8% (22/139), all occurring in Group A (22/101); Group B had no SMF at 1mo after surgery (0/38, P=0.002). The incidence of persistent SMF at 1mo after surgery in Group A1 was 50% (14/28), and in Group A2 was 11.0% (8/73, P<0.001). Significant differences were shown between the presence and absence of persistent SMF on foveola-off RRD, the preoperative BCVA, the 1mo postoperative BCVA, and the degree of the BCVA improvement from 1mo postoperatively to the final follow-up (P<0.05). However, there were no significant differences in the final BCVA (P>0.05). CONCLUSION: Persistent SMF after PPV for retinal detachment is associated with preoperative macular status. Macula-uninvolving RRD shows no persistent SMF after PPV. Macular partly detached RRD has a higher incidence of SMF than macula totally detached RRD after PPV. The persistence of SMF may be responsible for the delayed visual recovery, whereas there were no significant differences in the final visual acuity.

Effect of intravitreal conbercept treatment before vitrectomy in proliferative diabetic retinopathy.

AIM: To evaluate the safety and efficacy of intravitreal conbercept (IVC) injections as pretreatment for pars plana vitrectomy (PPV) in severe proliferative diabetic retinopathy (PDR). METHODS: This was a retrospective chart review of all patients who underwent PPV for PDR from January 2014 to October 2016. Patients who underwent IVC injection before PPV were assigned to the IVC group; the others were assigned to the control group. The IVC was performed 3-7d before surgery in the IVC group. All the eyes in the two groups were operated by the same doctor to complete the vitrectomy. Intraoperative complications and the changes in best-corrected visual acuity (BCVA) before and after surgery were compared between the two groups. RESULTS: A total of 68 eyes of 63 patients (22 eyes in the IVC group and 46 eyes in the control group) were examined. The risk of intraoperative bleeding was lower in the IVC group (2/22) than in the control group (25/46, P=0.000). Furthermore, the use of endodiathermy was significantly lower in the IVC group (1/22) than in the control group (12/46, P=0.047). The surgical time in the IVC group (112.64±34.52min) was significantly shorter than in the control group (132.85±40.04min, P<0.05). Compared to the BCVA before surgery, the mean BCVA was significantly improved after surgery for both groups (P<0.05). CONCLUSION: PPV is an effective treatment and can improve vision in patients with PDR. Preoperative intravitreal injection of conbercept could reduce the chances of intraoperative bleeding and the use of endodiathermy and shorten the operative time, which are beneficial in the management of PDR.

Feasibility study on robot-assisted retinal vascular bypass surgery in an ex vivo porcine model.

PURPOSE: To describe a new robot-assisted surgical system for retinal vascular bypass surgery (RVBS) and to compare the success rate with freehand RVBS. METHODS: A robot-assisted system for retinal microsurgery was constructed to include two independent robotic arms. A 23-gauge light probe and an intraocular forceps were affixed to the arm end effectors to perform the intraocular manipulation. Harvested porcine eyes were introduced to be established animal models of closed-sky eyeballs after that pars plana vitrectomy using temporary keratoprosthesis was performed by a skilful surgeon. Retinal vascular bypass surgery (RVBS) was performed by an inexperienced ophthalmologist to test the ease of use. A stainless steel wire (45-µm pipe diameter) was used as an artificial vessel. Before RVBS, the wires were prepositioned at the retinal surface of the eyes. The Control group (n = 20) underwent freehand RVBS, and the Experimental group (n = 20) underwent robot-assisted RVBS. To create the simulated bypass, the distal end of the wire was inserted into the selected vessel and advanced ~4 mm away from the optic disc. If successful, then the proximal wire end was inserted and advanced ~2 mm towards the optic disc. The difference in the success rate for the freehand and robot-assisted procedures was analysed by the chi-square test. RESULTS: The success rate for the freehand RVBS was 5% (1/20 eyes). In contrast, the robot-assisted success rate was 35% (7/20) of eyes (p < 0.05). CONCLUSION: This study demonstrated the feasibility of robot-assisted RVBS in ex vivo porcine eyes. The robotic system increased the accuracy and stability of manipulation by eliminating freehand tremor, leading to a higher surgical success rate.

Findings of perinatal ocular examination performed on 3573, healthy full-term newborns.

OBJECTIVE: To document the findings of a newborn eye examination programme for detecting ocular pathology in the healthy full-term newborn. METHODS: This is a cross-sectional study of the majority of newborns born in the Kunming Maternal and Child Healthcare Hospital, China, between May 2010 and June 2011. Infants underwent ocular examination within 42 days after birth using a flashlight, retinoscope, hand-held slit lamp microscope and wide-angle digital retinal image acquisition system. The retinal fundus examination utilised the RetCam wide-field digital imaging system (Clarity Medical Systems, Pleasanton, California, USA). The external eye, pupillary light reflex, red reflex, opacity of refractive media, anterior chamber and posterior segments were also examined. RESULTS: A total of 3573 healthy full-term newborns were enrolled and examined in the programme. There was detection of 871 abnormal cases (24.4%). The majority of abnormal exams were 769 (21.52%) retinal haemorrhages. Of these, there were 215 cases of significant retinal haemorrhage, possible sight threatening or amblyogenic, representing 6.02% of the total. In addition, 67 cases (1.88%) involved macular haemorrhage. The other 107 cases (2.99%) with abnormal ocular findings included subconjunctival haemorrhage, congenital microphthalmos, congenital corneal leukoma, posterior synechia, persistent pupillary membrane, congenital cataract, enlarged C/D ratio, retinal hamartoma versus retinoblastoma, optic nerve defects, macular pigment disorder and non-specific peripheral retinopathy. CONCLUSION: Ocular examination of healthy newborns leads to the detection of a significant number of ocular pathologies. The most commonly discovered ocular abnormality during examination of the newborns in this study is retinal haemorrhage. The long-term impact of these findings is unknown. Although presumed by some to benign, neonatal retinal haemorrhages due to birth trauma could be involved in altering visual development. Further work, including prospective examination of newborns with long-term follow-up, is needed and supported by our findings.