Interventional procedure overview of trabeculectomy with a biodegradable collagen matrix implant for glaucoma
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Summary of key evidence on trabeculectomy with a biodegradable collagen matrix implant for glaucoma
Study 1 Song DS (2019)
Study type | Systematic review and meta-analysis |
|---|---|
Country | Egypt (n=4), Germany (n=2), China (n=1), India (n=1), UK, (n=1), Italy (n=1), Iran (n=1) |
Recruitment period | Search period: April 1966 to April 2018 |
Study population and number | n = 11 studies 443 eyes in patients with glaucoma (n=217 trabeculectomy with biodegradable collagen implant versus n=226 trabeculectomy with MMC) |
Age and sex | biodegradable collagen implant group: Mean age 48 to 67.9 years, sex not reported MMC group: Mean age 45 to 65 years, sex not reported |
Patient selection criteria | Inclusion criteria: Prospective cohort studies; study including patients with glaucoma where traditional therapies have been unsuccessful; studies comparing the outcome of trabeculectomy with biodegradable collagen implant implant versus trabeculectomy with MMC; minimum follow up of 6 months; at least 1 of the outcomes of interest included. Exclusion criteria: Retrospective studies; studies involving other types of glaucoma surgery; studies including paediatric cases or patients with repeated glaucoma surgery; conference abstracts, editorials, duplicate publications, letters, or reviews. |
Technique | Trabeculectomy followed either by implantation of biodegradable collagen matrix implant (Ologen Collagen Implant, Aeon Astron Europe, Netherlands) or application of MMC depending on the allocated group. |
Follow up | Varied across studies (range 1 to 60 months) |
Conflict of interest/source of funding | No conflicts of interest reported. Study funded by Young Medical Talents Foundation of Jiangsu Province (grant no. QNRC2016080). |
Analysis
Study design issues:
Systematic searches were done, studies were screened and data extracted by 2 independent researchers; disagreements were resolved through discussion with a third researcher. Quality of the included studies was evaluated based on the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) methodology which were classified into levels of very low, low, moderate, and high. High risk of detection and performance bias was observed across the included studies.
The primary outcome of interest was the IOP reduction (IOPR) following trabeculectomy. The secondary outcome measures included complete success and qualified success rate, and the reduction in glaucoma medications.
Study population issues: one study (with 20 patients with juvenile open-angle glaucoma) was included in the analysis.
Other issues: One study (Yuan 2015) which presented a higher baseline IOP (>40mmHg) was excluded from pooled analyses by the authors to decrease between-study heterogeneity.
The total number of eyes in the biodegradable collagen implant group was counted twice in 1 included study (Eldaly 2017), which reported 2 separate analyses for different MMC concentrations using the same set of collagen implant eyes for both analyses.
There is an overlap of 6 primary studies (122 patients) included in study 2.
Key efficacy findings
Number of patients analysed: 443 eyes (217 trabeculectomy plus biodegradable collagen implant versus 226 trabeculectomy plus MMC).
Follow-up period | No of studies | MD (95% CI) | I2 | P value |
|---|---|---|---|---|
1 month | 8 studies (165 collagen implant versus 173 MMC) | -3.69 (-6.70 to -0.68) | 0% | 0.02 |
3 months | 9 studies (179 collagen implant versus 187 MMC) | -2.69 (95% CI -5.17 to -0.21) | 0% | 0.03 |
6 months | 10 studies (186 collagen implant versus 194 MMC) | -3.67 (95% CI -6.09 to -1.25) | 16% | 0.003 |
12 months | 7 studies (122 collagen implant versus 122 MMC) | -3.24 (95% CI -6.08 to -0.41) | 51% | 0.03 |
24 months | 2 studies (27 collagen implant versus 28 MMC) | 1.24 (95% CI -9.43 to 11.90) | 0% | 0.82 |
5 years | 1 study (20 collagen implant versus 20 MMC) | 1.10 (95% CI -10.11 to 12.31) | - | 0.85 |
Reduction in IOP after 1 month: WMD -3.69 (95% CI -6.70 to -0.68), I2=0%, p=0.02 (8 studies; 165 biodegradable collagen implant and 173 MMC)
Reduction in IOP after 3 months: WMD -2.69 (95% CI -5.17 to -0.21), I2=0%, p=0.03 (9 studies; 179 biodegradable collagen implant and 187 MMC)
Reduction in IOP after 6 months: WMD -3.67 (95% CI -6.09 to -1.25), I2=16%, p=0.003 (10 studies; 186 biodegradable collagen implant and 194 MMC)
Reduction in IOP after 12 months: WMD -3.24 (95% CI -6.08 to -0.41), I2=51%, p=0.03 (7 studies; 122 biodegradable collagen implant and 122 MMC)
Reduction in IOP after 24 months: WMD 1.24 (95% CI -9.43 to 11.90), I2=0%, p=0.82 (2 studies; 27 biodegradable collagen implant and 28 MMC)
Reduction in IOP after 5 years: WMD 1.10 (95% CI -10.11 to 12.31), p=0.85 (1 study; 20 biodegradable collagen implant and 20 MMC)
Outcome | Follow up (months) | Number of studies reporting outcome | Collagen implant group mean±SD | MMC group mean±SD |
|---|---|---|---|---|
IOP (mmHg) | 1 | 10 | 17.13 (10.07) | 18.06 (6.23) |
3 | 9 | 17.05 (7.44) | 16.51 (5.53) | |
6 | 12 | 14.99 (7.50) | 15.56 (3.78) | |
12 | 9 | 27.70 (9.43) | 15.73 (6.60) | |
24 | 2 | 12.17 (3.3) | 10.64 (2.49) | |
60 | 2 | 27.70 (9.43) | 17.37 (6.91) | |
IOP (mmHg) (excluding Yuan study)* | 1 | 9 | 14.45 (8.70) | 16.32 (4.71) |
3 | 8 | 14.53 (4.59) | 14.91 (4.10) | |
6 | 11 | 12.66 (4.96) | 14.08 (3.95) | |
12 | 8 | 12.84 (6.14) | 13.51 (5.04) | |
24 | 2 | 12.17 (3.3) | 10.64 (2.49) | |
60 | 1 | 12.10 (5.2) | 10.90 (4.51) | |
No. of medications used | 6 | 4 | 2.56 (1.02) | 2.88 (1.14) |
12 | 3 | 2.63 (1.27) | 2.74 (1.24) | |
24 | 2 | 2.45 (1.54) | 2.40 (1.48) |
*excluded this outlier study from pooled analyses which presented a higher baseline IOP (>40mmHg) to decrease between-study heterogeneity.
Follow up | MD (95% CI) | P value |
|---|---|---|
6 months | -6.80 (-14.75 to 1.16) | 0.09 |
12 months | -25.16 (-45.26 to -5.05) | 0.01 |
24 months | 5.33, (-1.65 to 12.30) | 0.13 |
Complication | No of studies reporting outcome | Collagen implant % (no of patients) | MMC % (no of patients) | Pooled RR (95% CI) | I2 (%) | P value between groups |
|---|---|---|---|---|---|---|
Complete success* | 11 | 8.9 (138/217) | 10.9 (156/226) | 0.91 (0.74,1.13) | 59 | 0.39 |
Qualified success^ | 11 | 10.9 (201/217) | 6.6 (198/226) | 1.02 (0.97,1.07) | 1 | 0.51 |
*defined as target endpoint IOP (usually 21mm Hg) without medications.
^defined as the target endpoint IOP with or without medications.
Key safety findings
Complication | No of studies reporting | Collagen implant % (no of eyes) | MMC % (no of eyes) | Pooled RR (95% CI) | I2 (%) | P value between groups |
|---|---|---|---|---|---|---|
Bleb leak | 8 | 8.9 (12/135) | 10.9 (15/137) | 0.81 (0.41,1.63) | 5 | 0.56 |
Hyphaema | 9 | 10.9 (18/165) | 6.6 (11/167) | 1.65 (0.83,3.29) | 9 | 0.16 |
Shallow Anterior chamber | 9 | 10.5 (17/162) | 11.7 (20/171) | 0.88 (0.50,1.53) | 0 | 0.65 |
Hypotony | 10 | 13.7 (25/183) | 20.7 (40/193) | 0.64 (0.42,0.98) | 0 | 0.04 |
Encapsulated Bleb | 2 | 7.9 (3/38) | 4.3 (2/46) | 1.68 (0.30,9.43) | 0 | 0.56 |
Blebitis | 3 | 2.8 (3/109) | 4.2 (5/118) | 0.73 (0.21,2.47) | 0 | 0.61 |
Hypotony maculopathy | 1 | 20 (4/20) | 40 (8/20) | 0.50 (0.18,1.40) | - | 0.19 |
Choroidal detachment | 5 | 9.5 (9/95) | 10.3 (10/97) | 1.10 (0.56,2.15) | 0 | 0.78 |
Anterior chamber reaction | 5 | 18 (18/100) | 16.6 (17/102) | 1.09 (0.61,1.93) | 0 | 0.78 |
Suture lysis | 1 | 15 (3/20) | 50 (10/20) | 0.30 (0.10,0.93) | - | 0.04 |
Needling | 1 | 0 (0/20) | 20 (4/20) | 0.11 (0.01,1.94) | - | 0.13 |
Study 2 Wang X (2015)
Study type | Cochrane systematic review and meta-analysis |
|---|---|
Country | Individual studies from Italy (n=1), India (n=3), Germany (n=2), Egypt (n=1), Greece (n=1) |
Recruitment period | Search date: December 2014 |
Study population and number | n=327 patients (333 eyes) with glaucoma (8 studies; 162 eyes across 159 patients with trabeculectomy plus biodegradable collagen implant versus 151 eyes across 148 patients with trabeculectomy plus MMC, 20 eyes across 20 patients with trabeculectomy alone) |
Age | Mean age 46 to 66 years, 40% to 59% male |
Patient selection criteria | Inclusion criteria: RCTs comparing devices used during trabeculectomy with trabeculectomy alone; RCTs where antimetabolites were used in one or both treatment groups were also included. Exclusion criteria: Non-RCTs or insufficient confirmation of RCT status; inclusion of children under 18 years of age where outcomes for adult participants were not reported separately; insufficient follow-up time. |
Technique | 7 studies compared trabeculectomy followed either by implantation of biodegradable collagen matrix implant (Ologen Collagen Implant, Aeon Astron Europe, Netherlands) or application of MMC depending on the allocated group. One study compared trabeculectomy alone versus trabeculectomy and biodegradable collagen implant without any use of MMC. No specific surgical techniques were reported. |
Follow up | Varied across studies (range 6 to 24 months) |
Conflict of interest/source of funding | One author reported receiving grants from the National Eye Institute, National Institutes of Health (US) and the Agency for Healthcare Research and Quality (AHRQ). Study funded by the National Eye Institute, National Institutes of Health and the NIHR. |
Analysis
Follow-up issues: 7 studies reported outcomes at 6 months, 5 studies reported outcomes at 1 year and 2 studies reported outcomes at 2 years.
Study design issues: This systematic review and meta-analysis aimed to evaluate the efficacy and safety of different devices as adjuncts to trabeculectomy compared with standard trabeculectomy in eyes with glaucoma. 33 studies were included, but 8 studies assessed the use of a biodegradable collagen matrix implant. Evidence on other devices is out of the scope of this overview and is not presented here.
Studies were screened independently and data extracted by 2 authors; disagreements were resolved through discussion with a third author. Quality of the included studies was evaluated based on the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) methodology which were classified into levels of very low, low, moderate, and high. The overall quality of the included studies relating to a biodegradable collagen implant was classed as "very low" and the majority of studies were at high or unclear risk of detection and selection bias.
The primary outcome of interest was change in IOP after one year, and secondary outcomes of interest included BCVA, visual field change, quality of life and frequency of complications
Study population issues: The studies included in this systematic review were very heterogenous and covered various types of glaucoma (including open-angle, angle-closure, and uncontrolled IOP). Studies did not stratify data by type of glaucoma.
Other issues: For the collagen implant studies, one study compared trabeculectomy without MMC versus trabeculectomy and collagen implant (Papaconstantinou 2010). The authors state that the lack of use of MMC in this study may have reduced the success rate of the trabeculectomy-alone group in comparison to the trabeculectomy-with-collagen implant group (favouring the trabeculectomy-with-collagen implant group).
There is overlap of 6 included primary studies (122 patients) with study 1.
Key efficacy findings
Number of patients analysed: 327 (333 eyes)
Outcome | Illustrative comparative risks* (95% CI) | No of eyes (studies) | Comments | |
|---|---|---|---|---|
Trabeculectomy plus MMC | Trabeculectomy plus collagen implant | |||
Postoperative mean IOP at 1 year | 15.2 mm Hg (range 11 to 19.3 mm Hg) | MD 1.40 mm Hg (95% CI 0.57 to 3.38) | 177 (5 studies) | Analysed using the generic inverse method |
Postoperative mean logMAR* BCVA at 1 year | See comment | See comment | - | Senthil 2013 reported BCVA for 32 eyes at 6 weeks post-surgery: MD -0.24 logMAR, 95% CI -0.58 to 0.10 |
*logMAR = logarithm of the minimum angle of resolution.
The quality of evidence was assessed for postoperative mean IOP at 1 year and reported as "very low" due to limitations in the design and implementation of available studies, high probability of reporting bias and imprecision in results (i.e. wide confidence intervals).
Follow-up period | No of studies | MD (95% CI) | I2 value (%) | P value |
|---|---|---|---|---|
Day 1 | 5 studies (162 eyes; 81 trab + collagen implant versus 81 trab+MMC) | 0.51 (-1.95 to 2.97) | 54.81 | 0.68 |
6 months | 5 studies (114 eyes, 114 trab + collagen implant versus 122 trab + MMC) | 0.43 (-0.97 to 1.84) | 53.5 | 0.55 |
Change from baseline to 6 months | 2 studies (46 eyes, 23 trab + collagen implant versus 23 trab + MMC) | -1.24 (-6.23 to 3.76) | 0 | 0.63 |
1 year | 5 studies (177 eyes, 82 trab + collagen implant versus 95 trab + MMC) | 1.4 (-0.57 to 3.38) | 53.49 | 0.16 |
Change from baseline to 1 year | 2 studies (44 eyes, 21 trab + collagen implant versus 23 trab + MMC) | -0.32 (-5.88 to 5.24) | 0 | 0.91 |
2 years | 2 studies (55 eyes, 27 trab + collagen implant versus 28 trab + MMC) | 0.2 (-1.29 to 1.69) | 33.57 | 0.79 |
Mean change of IOP from baseline to one year (biodegradable collagen implant group) = WMD: -0.32 (95% CI -5.88 to 5.24, 2 studies, n=21 eyes; I2=0%, p=0.91)
Postoperative IOP at one year (biodegradable collagen implant group) = WMD: 1.40 (95% CI 0.57 to 3.38, 5 studies, n=82 eyes; I2=53%, p=0.16)
Postoperative IOP at day one (biodegradable collagen implant group) = WMD: 0.51 (95% CI -1.95 to 2.97, 5 studies, n=82 eyes; I2=54.8%, p=0.68)
Change in IOP from baseline to 6 months = WMD: -1.24 (95% CI -6.23 to 3.76, 2 studies, n=23 eyes; I2=0%, p=0.63)
Postoperative IOP at 6 months (biodegradable collagen implant group) = WMD: 0.43 (95% CI -0.97 to 1.84, 5 studies, n=114 eyes; I2=53.5%, p=0.55)
Postoperative IOP at 2 years (biodegradable collagen implant group) = WMD: 0.20 (95% CI -1.29 to 1.69, 2 studies, n=27 eyes; I2=33.6%, p=0.79)
Key safety findings
Complication (follow-up range 6-24 months) | Illustrative comparative risks* (95% CI) | Collagen implant versus trab+MMC Relative effect (95% CI) | No. of studies | No. of eyes | I2 value (%) | P value | |
|---|---|---|---|---|---|---|---|
Trabeculectomy plus MMC | Biodegradable collagen implant | ||||||
Hypotony | 223 per 1000 | 167 per 1000 (105 to 265) | 19/112 versus 27/121, RR 0.75 (0.47 to 1.19) | 6 | 233 | 0 | 0.22 |
Shallow anterior chamber | 90 per 1000 | 71 per 1000 (29 to 174) | 7/102 versus 9/111, RR 0.79 (0.32 to 1.93) | 5 | 213 | 0 | 0.60 |
Bleb leakage | 138 per 1000 | 117 per 1000 (46 to 304) | 7/64 versus 9/65, RR 0.85 (0.33 to 2.20) | 4 | 129 | 0 | 0.73 |
Hyphaema | 78 per 1000 | 114 per 1000 (40 to 327) | 16/114 versus 9/115, RR 1.46 (0.51 to 4.19) | 6 | 229 | 25.3 | 0.48 |
Surgical revision within 3 months | 40 per 1000 | 68 per 1000 (15 to 305) | 7/75 versus 3/75, RR 1.70 (0.38 to 7.63) | 4 | 150 | 17.9 | 0.49 |
Blebitis or endophthalmitis | - | - | 2/78 versus 1/86, RR 1.57 (0.25 to 9.70) | 3 | 164 | 0 | 0.63 |
Choroidal detachment | - | - | 7/64 versus 9/65, RR 0.83 (0.33 to 2.09) | 4 | 129 | 0 | 0.70 |
Anterior chamber reaction | - | - | 10/49 versus 9/50, RR 1.21 (0.56 to 2.60) | 2 | 99 | 0 | 0.62 |
Positive Seidel test | - | - | 3/78 versus 1/86, RR 1.93 (0.32 to 11.54) | 3 | 164 | 0 | 0.47 |
Tenon's cysts | - | - | 5/58 versus 6/66, RR 0.88 (0.21 to 3.66) | 3 | 124 | 19.1 | 0.86 |
The quality of evidence was assessed for hypotony, shallow anterior chamber, bleb leakage, hyphaema and surgical revision – all were reported as "very low" due to limitations in the design and implementation of available studies, high probability of reporting bias and imprecision in results (i.e. wide confidence intervals). Follow up in studies ranged from 6-24 months.
Study 3 Bhatkoti B (2021)
Study type | Randomised controlled trial |
|---|---|
Country | India |
Recruitment period | Not reported. |
Study population and number | N=33 patients (40 eyes) with primary open-angle glaucoma (POAG trabeculectomy with Express Shunt (20 eyes) versus biodegradable collagen matrix implant (20 eyes) |
Age and sex | Mean age: Group A 65.7 ± 1.75 years; Group B 64.6 ± 1.68 years Sex: Group A: 17/20 eyes in men; Group B: 14/20 eyes in men |
Patient selection criteria | Inclusion criteria: patients with POAG, more than 40 years of age, with inadequate IOP control (>21 mm Hg) measured by Goldmann Applanation tonometry (GAT), on 3 or more topical antiglaucoma drugs over 4 weeks. Exclusion criteria: patients with other form of primary or secondary glaucoma, aphakic or pseudophakic patients with anterior chamber/iris fixated or sclera fixated Intraocular lens, uveitis, any intraocular surgery and those with retinal pathologies. |
Technique | Augmented trabeculectomy under peribulbar anaesthesia Group A: 20 eyes (trabeculectomy with Ex-Press Shunt) versus Group B: 20 eyes (trabeculectomy with Ologen implant) Both procedures included surface modification with MMC before implant insertion. |
Follow up | 6 months |
Conflict of interest/source of funding | None; study was funded by the Directorate General Armed Forces Medical Services and Defence Research Development Organization, Government of India. |
Analysis
Follow-up issues: short follow-up period.
Study design issues: small randomised double blinded study. Single surgeon performed all surgeries.
Key efficacy findings
Number of patients analysed: 33 (40 eyes)
IOP (mm Hg) | Group A (Express shunt) Mean ±SD | Mean difference (SE) | P value | Group B (biodegradable collagen implant) Mean ±SD | Mean difference (SE) | P value |
|---|---|---|---|---|---|---|
Baseline | 23.70 ± 4.6 | 26.00 ± 4.0 | ||||
1 week | 10.80 ± 4.9 | 12.9 (1.05) | <0.05 | 9.50 ± 5.7 | 16.5 (1.83) | <0.05 |
4 weeks | 13.00 ± 5.7 | 10.7 (1.29) | <0.05 | 14.40 ± 4.9 | 11.6 (1.36) | <0.05 |
8 weeks | 13.70 ± 4.7 | 10.0 (1.39) | <0.05 | 14.90 ± 4.6 | 11.1 (0.89) | <0.05 |
12 weeks | 14.30 ± 3.7 | 9.4 (1.04) | <0.05 | 15.20 ± 5.2 | 10.8 (1.12) | <0.05 |
6 months | 15.80 ± 4.5 | 7.9 (1.17) | <0.05 | 14.70 ± 4.1 | 11.3 (1.17) | <0.05 |
P<0.05 between groups at baseline.
Visual acuity (mean LogMAR) | Group A (Express shunt) Mean ±SD | Mean difference (SE) | P value | Group B (biodegradable collagen implant) Mean ±SD | Mean difference (SE) | P value |
|---|---|---|---|---|---|---|
Baseline | 0.35 ± .44 | 0.28 ± 0.36 | ||||
1 week | 0.67 ± .49 | -0.317 (0.039) | <0.05 | 0.67 ± 0.41 | -0.389 (0.061) | <0.05 |
4 weeks | 0.44 ± .45 | -0.089 (0.028) | 0.070 | 0.53 ± 0.40 | -0.243 (0.045) | <0.05 |
8 weeks | 0.39 ± .44 | -0.037 (0.019) | 0.965 | 0.53 ± 0.40 | -0.127 (0.041) | 0.085 |
12 weeks | 0.39 ± .43 | -0.039 (0.028) | 1.000 | 0.31 ± 0.43 | -0.030 (0.044) | 1.000 |
6 months | 0.41 ± .44 | -0.054 (0.041) | 1.000 | 0.31 ± 0.43 | -0.030 (0.044) | 1.000 |
P<0.05 between groups at baseline.
Time since surgery | Group A (Express shunt) | Group B (biodegradable collagen implant) | P value |
|---|---|---|---|
1 week | 0 | 0 | - |
4 weeks | 1 | 1 | 1.000 |
8 weeks | 2 | 7 | 0.58 |
12 weeks | 6 | 8 | 0.507 |
6 months | 6 | 7 | 0.736 |
Group A (Express shunt) | Group B (biodegradable collagen implant) | P value | |
|---|---|---|---|
Complete success* | 70% (14/20) | 60% (12/20) | Not significant |
Qualified success^ | 15% (3/20) | 25% (5/20) | Not significant |
Failure | 15% (3/20) | 15% (3/20) | Not significant |
*defined as IOP of less than or equal to 21 mm Hg at 6 months postoperative.
^ use of additional antiglaucoma medications.
Key safety findings
Complication | Group A (Express shunt) % (n=20) | Group B (biodegradable collagen implant) % (n=20) |
|---|---|---|
Early complications (within 30 days) total | 35 (7) | 50 (10) |
Hyphaema | 5 (1) | 15 (3) |
Lens cornea touch due to malignant glaucoma | 5 (1) | 0 |
Hypotony with shallow anterior chamber (over filtration) | 20 (4) | 25 (5) |
Bleb leak | 5 (1) | 0 |
Choroidal detachment | 0 | 10 (2) |
Late complications total | 20 (4) | 30 (6) |
Encapsulated bleb | 5 (1) | 10 (2) |
Cataract | 5 (1) | 5 (1) |
Flat avascular bleb | 10 (2) | 15 (3) |
Study 4 Tranos P (2010)
Study type | Case report |
|---|---|
Country | Greece |
Recruitment period | Not reported |
Study population and number | n = 3 patients with glaucoma |
Age and sex | Age range: 73-89 years, 1 male and 2 female |
Patient selection criteria | Not applicable |
Technique | Trabeculectomy followed by implantation of biodegradable collagen matrix implant (Ologen Collagen Implant, Aeon Astron Europe, Netherlands). |
Follow up | 6-8 months |
Conflict of interest/source of funding | None |
Key safety findings
Patient 1
A 73-year-old man with end-stage POAG underwent uncomplicated trabeculectomy with biodegradable collagen implant.
Three days after uncomplicated trabeculectomy with biodegradable collagen implant, IOP was 8 mmHg with an elevated microcystic filtration bleb and visual acuity (VA) 6/24. A day later the patient complained of blurred vision and visual acuity decreased to 6/60. Fundoscopy revealed central retinal vein occlusion (CRVO) with retinal haemorrhages involving the macula. Six months later, VA improved to 6/24 following absorption of macular haemorrhage.
Patient 2
Routine trabeculectomy with biodegradable collagen implant was performed in an 89- year-old hypertensive woman with end-stage glaucoma. Preoperative IOP was 26 mm Hg and vertical cup disc ratio was 0.95. Two days postoperatively, IOP was 10 mmHg and the anterior chamber well-formed, but she developed CRVO and experienced mild VA reduction from 6/36 to 6/60, which remained unchanged 6 months later.
Patient 3
A 73-year-old hypertensive woman underwent uncomplicated trabeculectomy with biodegradable collagen implant. Six days postoperatively CRVO was noted with IOP of 11 mmHg (lower end of normal range). Because there was no macular involvement her VA remained unchanged at 6/18; 8 months later disc collateral vessels, were evident.
Authors assume that there are no mechanisms that could link biodegradable collagen implant with CRVO in any of the patients.
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