Risk factors for flat anterior chamber after glaucoma filtration surgery

AIM： To investigate the incidence rate and risk factors for grade Ⅲ flat anterior chamber（FAC） after glaucoma filtration surgery based on 5-year data.METHODS： Patients who underwent glaucoma filtration surgery in Daping hospital from January 2009 to December 2013 were enrolled in this retrospective study. The incidence of grade Ⅲ FAC following glaucoma filtration surgery was determined. Regression analysis was performed to investigate the influence of glaucoma type, surgical approach, age, and preoperative intraocular pressure（IOP） on the risk of postoperative FAC.RESULTS： A total of 2179 eyes receiving anti-glaucoma surgery were included. Ninety-one eyes suffered from postoperative FAC, with an overall incidence rate of 4.18%. Of 471 eyes with primary open angle glaucoma（POAG）, grade Ⅲ FAC occurred in only 3 eyes（0.64%）. Primary angleclosure glaucoma（PACG） was diagnosed in 1076 eyes, 39（3.62%） of which developed grade Ⅲ FAC, including 12 eyes（12/300, 4%） with acute PACG（aP ACG） and 27 eyes（27/776, 3.48%） with chronic PACG（c PACG）. Six of 259 eyes（2.32%） with secondary glaucoma, 28 of 186 eyes（15.05%） with neovasular glaucoma, 1 of 66 eyes（1.52%） with congenital glaucoma, and 14 of 115 eyes（12.17%） with remnant glaucoma suffered from grade Ⅲ FAC. Of 6 eyes with mixed glaucoma, none developed grade Ⅲ FAC after surgery. When stratified by surgical approach, 24 of 766 eyes（3.13%） undergoing trabeculectomy, 21 of 924 eyes（2.27%） treated by trabeculectomy plus mitomycin C（MMC）, 18 of 109 eyes（16.51%） undergoing Ahmed glaucoma valve implantation, 23 of 201 eyes（11.44%） managed by Ahmed implantation plus MMC, and 5 of 133 eyes（3.76%） treated by Ahmed implantation plus lens extraction or vitrectomy developed grade Ⅲ FAC. Logistic regression analysis revealed that factors including neovasular glaucoma, remnant glaucoma, glaucoma valve implantation, glaucoma valve implantation＋MMC, glaucoma valve implantation＋vitrectomy, age〉60 y, and IOP at admission 〉50 mm Hg were significantly associated with an increased risk for grade Ⅲ FAC.CONCLUSION： The overall incidence of grade Ⅲ FAC after glaucoma filtration surgery is 4.18%. Patients with neovasular glaucoma and remnant glaucoma are at a higher risk of developing FAC. Ahmed glaucoma valve implantation is associated with a higher risk for grade Ⅲ FAC compared with trabeculectomy. No significant correlation was observed between the use of MMC in glaucoma filtration surgery and the risk of postoperative FAC. Higher IOP at admission（〉50 mm Hg） and old age（〉60 y） are risk factors for grade Ⅲ FAC.

Effect of poly（DL-lactide-co-glycolide） on scar formation after glaucoma filtration surgery

Background Glaucoma filtering surgery （GFS） is the most common procedure performed in the treatment of glaucoma.Although antiscarring agents help prevent postsurgical scarring and improve glaucoma surgical outcomes,they may be associated with an increased incidence of severe and potentially blinding complications.Poly（DL-lactide-co-glycolide） （PDLLA/GA） is a bioresorbable polymer,which can be prepared with a large range of physical,mechanical,and biological properties and has been widely used in medicine,including as an absorbable suture and a drug carrier and especially as a scaffold in tissue engineering.This study aimed to evaluate the effect of PDLLA/GA on scar formation after glaucoma filtration surgery （GFS）.Methods Forty-eight New Zealand white rabbits were divided into two groups randomly and GFS was performed on the right eye of each.PDLLA/GA membranes were put under the sclera flap for evaluation.GFS with no membrane inserted served as control.Clinical evaluations of intraocular pressure （lOP） and the presence of a filtration bleb were performed at intervals （3 days,1,2,4,8,12,20,and 24 weeks） postoperatively.At each time point,three eyes per group were excised to observe histological changes such as inflammation and scar formation and the expression of collagen type Ⅳ,proliferating cell nuclear antigen （PCNA）,matrix metalloproteinase-9 （MMP-9）,and tissue inhibitor of metalloproteinase-1 （TIMP-1）.The expression of connective tissue growth factor （CTGF） mRNA was determined by reverse transcription-polymerase chain reaction.Results The lower lOP level and an effective bleb were maintained for a long time after GFS in the PDLLA/GA group.The histological analysis showed less inflammation and scar formation,weaker expression of collagen type Ⅳ and PCNA,more intense MMP-9 and TIMP-1,slightly elevated ratio of MMP-9 and TIMP-1,and a smaller increase in CTGF mRNA postoperatively in the PDLLA/GA group but less than the control group （P ＜0.05）.Conclusion PDLLA/GA membranes may be promising for preventing fibrosis after GFS.

Trend of glaucoma internal filtration surgeries in a tertiary hospital in China

AIM:To evaluate the trend of glaucoma internal filtration surgeries for inpatients between 2015 and 2021 at the Eye Hospital of Wenzhou Medical University.METHODS:A review of the medical records of inpatients who had been diagnosed with glaucoma and received antiglaucoma surgery between January 1,2015 and December 31,2021 was conducted.The glaucoma diagnosis in this study included primary open angle glaucoma,primary angleclosure glaucoma,secondary glaucoma,and paediatric glaucoma.The types of surgeries were categorised as internal filtration,external filtration,and cyclodestruction surgery based on the pathway of aqueous humor outflow.The trend of these glaucoma surgeries in the sample of patients with different types of glaucoma was then analysed.RESULTS:The number of patients hospitalised for glaucoma surgery increased yearly,from 752 in 2015 to 1373 in 2021,at the Eye Hospital of Wenzhou Medical University.Regarding the patients diagnosed with primary open angle glaucoma,internal filtration surgery increased from 27.40%of the sample to 54.40%of the sample,while external filtration surgery decreased from 71.50%to 44.20%between 2015 and 2021.For paediatric glaucoma,internal filtration surgery increased from 37.50%in 2015 to 88.20%in 2021.Whilst different types of surgeries were performed on the sample of patients with secondary glaucoma,the proportion of internal filtration surgery also showed an increase from 18.20%in 2015 to 40.90%in 2021.Meanwhile,internal filtration surgery in the patient sample with primary angle-closure glaucoma already accounted for over 70.00%in 2015,and showed a small increase by 2021.CONCLUSION:As surgical technology and surgical experience continue to elevate and improve,the range of glaucoma surgeries are correspondingly evolving.This study find that internal filtration surgeries accounted for an increasing proportion of treatments in the surgical management of glaucoma between 2015 and 2021.

Discrimination and quantification of scar tissue by Mueller matrix imaging with machine learning

Scarring is one of the biggest areas of unmet need in the long-term success of glaucoma filtration surgery.Quantitative evaluation of the scar tissue and the post-operative structure with micron scale resolution facilitates development of anti-fibrosis techniques.However,the distinguishment of conjunctiva,sclera and the scar tissue in the surgical area still relies on pathologists'experience.Since polarized light imaging is sensitive to anisotropic properties of the media,it is ideal for discrimination of scar in the subconjunctival and episcleral area by characterizing small differences between proportion,organization and the orientation of the fibers.In this paper,we defined the conjunctiva,sclera,and the scar tissue as three target tissues after glaucoma filtration surgery and obtained their polarization characteristics from the tissue sections by a Mueller matrix microscope.Discrimination score based on parameters derived from Mueller matrix and machine learning was calculated and tested as a diagnostic index.As a result,the discrimination score of three target tissues showed significant difference between each other(p<0.001).The visualization of the discrimination results showed significant contrast between target tissues.This study proved that Mueller matrix imaging is effective in ocular scar discrimination and paves the way for its application on other forms of ocular fibrosis as a substitute or supplementary for clinical practice.

Effectiveness of conjunctival bleb scarring by knockdown of heat shock protein 47 in rat model

AIM:To evaluate the effectiveness of knock-down of heat shock protein 47(HSP47)on conjunctival bleb scarring in a rat model and its possible mechanism.METHODS:Male Sprague–Dawley rats were used for glaucoma filtration surgery(GFS)and were treated with either phosphate buffered solution,shControl,mitomycin C,or sh-HSP47 using a microsyringe immediately after GFS.The morphology of filtering blebs was observed postoperatively.The levels of HSP47 were analyzed at 2,5,8,and 11d after GFS via real‑time quantitative polymerase chain reaction(PCR)and Western blot.The silencing effect of HSP47,the expression of collagen I and III,and the potential signaling pathways of HSP47 during scarification were explored 11d post GFS.The protein levels of transforming growth factor-β1(TGF-β1),phospho-Smad2(pSmad2),phospho-Smad3(p-Smad3),and phospho-p38(p-p38)were also analyzed using Western blot.RESULTS:Sh-HSP47 treatment significantly prolonged the functional filtration bleb retention.The levels of HSP47 were increased significantly at 5,8,and 11d postoperatively compared to the control group(P<0.05,P<0.01,and P<0.001).The levels of HSP47 protein at day 11 postoperatively were significantly down-regulated after HSP47 silencing using sh-HSP47 adenovirus transfection(P<0.01).Expression levels of collagen I and III within the blebs were significantly reduced in the absence of HSP47(P<0.01).Moreover,the protein levels of TGF-β1,p-Smad2/3,and p-p38 were dramatically inhibited after treatment with sh-HSP47(P<0.01).CONCLUSION:The inhibitory effects of HSP47 knockdown on scarring after GFS have the potential to be an efficacious therapeutic option for the treatment of conjunctival bleb scarring.

Inhibitory effect of three biopolymer materials on scar formation following trabeculectomy

AIM: To investigate the inhibitory effects of amniotic membrane, polylactic acid membrane and chitosan membrane on scar formation following trabeculectomy. METHODS: A total of 24 New Zealand white rabbits (48 eyes) were randomly divided into 4 groups: amniotic membrane group, polylactic acid membrane group, chitosan membrane group, and control group, with 6 rabbits (12 eyes) in each group. The left eyes underwent routine trabeculectomy, and the right eyes were considered as controls. Amniotic membrane, polylactic acid membrane and chitosan membrane were respectively installed under sclera flap in three groups, but any treatment was not applied in control group. Intraocular pressure, conjunctival filtering bleb, and anterior chamber inflammation responses were monitored at day 1, 3, 7, 14, 28 and 56 post-operatively. Eyeball tissue underwent histopathological examination at day 56 post-operatively. RESULTS: Fibrocytes and inflammatory cells were reduced in amniotic membrane, polylactic acid membrane and chitosan membrane groups compared to that in control group. At day 1 post-operatively, intraocular pressure was decreased in three membrane groups compared to that in control group. At day 14 post-operatively, the intraocular pressure was decreased significantly, while it of three membrane groups was significantly lower than that of preoperative (P<0.01). There were no significant differences among three membrane groups (P>0.05). Filtering bleb of four groups was clearly observed at day 7 post-operatively, but there was no significant difference in pair-wise comparison. At day 28 and 56 post-operatively, filtering bleb in control group was significantly narrowed compared to that in three membrane groups (P <0.05), but there was no significant difference in pair-wise comparison of three membrane groups. CONCLUSION: All amniotic membrane, polylactic acid membrane and chitosan membrane can effectively inhibit scar formation following trabeculectomy, the effect of amniotic membrane is the best.

Glaucoma surgery and induced astigmatism:a systematic review

Background:The refractive outcomes of glaucoma surgeries,particularly their effect on astigmatism,are incompletely understood.Main body:Trabeculectomy is associated with a considerable amount of with-the-rule astigmatic change in the immediate postoperative period.This is followed by a gradual against-the-rule shift.These changes are altered with the use of mitomycin C(MMC).Non-penetrating surgery such as deep sclerectomy is also associated with a similar or smaller degree of induced astigmatism.Minimally invasive glaucoma surgery appears to be astigmatically neutral.There is no clear evidence regarding refractive outcomes of glaucoma drainage device surgery.Conclusions:Induced astigmatism may account for a reduction in unaided visual acuity in the early postoperative period following a successful trabeculectomy.These changes appear to stabilise at 3 months,and it would be prudent to defer the prescription of new glasses until this time.If sequential cataract surgery is to be performed,toric intraocular lenses can be a useful option for astigmatic correction.