Trabeculectomy for open-angle glaucoma in phakic eyes vs in pseudophakic eyes after phacoemulsification: a prospective clinical cohort study.

IMPORTANCE: Whether pseudophakic eyes are resistant to trabeculectomy remains unknown. OBJECTIVE: To determine the effect of previous phacoemulsification on surgical success of trabeculectomy with mitomycin C for open-angle glaucoma. DESIGN, SETTING, AND PARTICIPANTS: Prospective clinical cohort study at Kumamoto University Hospital, Kumamoto, Japan, among patients 55 years or older having open-angle glaucoma with intraocular pressure (IOP) of 22 mm Hg or higher, including 39 phakic eyes (phakic group) and 25 pseudophakic eyes after phacoemulsification (pseudophakic group). INTERVENTION: Trabeculectomy with mitomycin C was performed. MAIN OUTCOMES AND MEASURES: The primary outcome measure was the probability of success at 1 year after trabeculectomy. Surgical failure was defined as the following 3 IOP levels: 21 mm Hg or higher (criterion A), 18 mm Hg or higher (criterion B), and 15 mm Hg or higher (criterion C). Secondary outcome measures included IOP, the number of postoperative antiglaucoma medications, and the number of laser suture lysis procedures, as well as postoperative complications. RESULTS: The probabilities of success at 1 year in the phakic vs pseudophakic groups were 95% vs 74% for criterion A (P = .02), 84% vs 62% for criterion B (P = .04), and 67% vs 53% for criterion C (P = .10). Only pseudophakia was significantly associated with outcome in the multivariable analysis for criterion A (relative risk, 9.37) and for criterion B (relative risk, 5.52) (P = .01 for both). Postoperative IOP in the pseudophakic group was significantly higher than that in the phakic group at 6 months (P = .03) and 9 months (P = .047) after trabeculectomy. No significant difference between groups was noted in postoperative complications or in the number of postoperative antiglaucoma medications or the number of laser suture lysis procedures. CONCLUSIONS AND RELEVANCE: Among patients with open-angle glaucoma, trabeculectomy with mitomycin C in pseudophakic eyes after phacoemulsification for target IOP of less than 21 mm Hg or less than 18 mm Hg is less successful compared with that in phakic eyes. No significant difference between phakic and pseudophakic eyes was observed for secondary outcome measures other than IOP. TRIAL REGISTRATION: clinicaltrials.gov Identifier: University Hospital Medical Information Network Clinical Trials Registry of Japan UMIN000001196.

Long-term outcomes and prognostic factors for trabeculectomy with mitomycin C in eyes with uveitic glaucoma: a retrospective cohort study.

PURPOSE: To elucidate the long-term outcomes and prognostic factors for trabeculectomy with mitomycin C (MMC) in eyes with uveitic glaucoma (UG). METHODS: A retrospective, consecutive, comparative cohort study was conducted with 204 patients who underwent trabeculectomy with MMC between 1999 and 2008 at 2 Japanese clinical centers. The study group included 101 eyes with UG and 103 eyes with primary open-angle glaucoma (POAG). Surgical failure was defined as intraocular pressure levels of ≥21 mm Hg or an additional glaucoma surgery. Kaplan-Meier survival curves for surgical failure were compared between UG and POAG eyes, and prognostic factors for surgical failure of trabeculectomy in UG eyes were analyzed by the Cox proportional hazards model. Secondary outcome measures included comparisons of the frequency of additional cataract surgery and other surgical complications after trabeculectomy between UG and POAG eyes. RESULTS: The mean follow-up periods (±SD) were 34.7±37.9 and 37.7±34.7 months (median, 24.0 and 27.4 mo) for UG and POAG, respectively. The subtypes of uveitis were granulomatous uveitis (n=20) including sarcoidosis (n=12), Vogt-Koyanagi-Harada disease (n=5) and varicella zoster virus uveitis (n=3), Behçet disease (n=10), Posner-Schlossman syndrome (n=5), and other types of UG (n=12). Fifty-four eyes were diagnosed with idiopathic UG. The 3-year probabilities of success after trabeculectomy were 71.3% and 89.7% for UG and POAG, respectively (P=0.0171). A multivariable model showed that UG eyes with previous cataract surgery [relative risk (RR)=2.957, P=0.0344)] and granulomatous uveitis (RR=3.805, P=0.0106) were associated with surgical failure. UG eyes experienced more frequent cataract surgeries after trabeculectomy than POAG eyes: the 3-year probabilities of additional cataract surgery of 62.6% and 10.7% for UG and POAG, respectively (P<0.0001). There was no significant difference in the frequency of surgical complications such as bleb leakage, hypotensive maculopathy, severe anterior-chamber hemorrhage, and infectious endophthalmitis. CONCLUSIONS: Trabeculectomy with MMC was less effective in maintaining intraocular pressure reduction in UG eyes than in POAG eyes. The prognostic factors for surgical failure of trabeculectomy in UG eyes were previous cataract surgery and granulomatous uveitis. In addition, UG eyes after trabeculectomy more frequently required additional cataract surgery.

Prognostic factors in trabeculectomy with mitomycin C having history of previous glaucoma surgery.

PURPOSE: To evaluate the prognostic factors for surgical outcomes of subsequent trabeculectomy with mitomycin C (MMC) after prior incisional glaucoma surgery. METHODS: We reviewed medical records of a total cohort of 781 trabeculectomies with MMC, and selected 125 patients (125 eyes). The primary endpoints included persistent intraocular pressure (IOP) of ≥21 or <5 mmHg, the need for additional glaucoma surgery and deterioration of visual acuity to no light perception. Univariate and Multivariate analyses were performed by using the Cox proportional hazards model. RESULTS: The mean follow-up period was 26.8 months. The probabilities of success at 1, 2, and 3 years were 80.6, 72.2, and 70.6 %, respectively. Multivariate analysis showed that a shorter time interval between prior glaucoma surgery and subsequent trabeculectomy [relative risk (RR), 0.8867/year; P = 0.0090] and the number of prior trabeculectomies (RR, 2.2645; P = 0.0029) were significant prognostic factors for subsequent failure of trabeculectomy with MMC. CONCLUSION: A short time period between prior glaucoma surgery and subsequent trabeculectomy and the number of prior trabeculectomies are associated with surgical failure of subsequent trabeculectomy with MMC.

[A prospective study of postoperative aqueous flare in trabeculectomy alone versus phacotrabeculectomy].

PURPOSE: To compare trabeculectomy alone with phacotrabeculectomy in postoperative aqueous flare. SUBJECTS AND METHODS: Aqueous flare was prospectively measured using a laser flare-cell meter in open-angle glaucoma patients with cataract undergoing trabeculectomy with either mitomycin C or phacotrabeculectomy with mitomycin C. Flare was measured before surgery and at 2 and 4 weeks after surgery. RESULTS: Twenty-four patients who underwent trabeculectomy and 26 patients who underwent phacotrabeculectomy completed the study. There were no significant differences in flare values between the two groups at any point. Logistic regression analysis demonstrated that exfoliation glaucoma (odds ratio = 8.978; p = 0.0028) and postoperatively shallow anterior chamber (odds ratio = 15.539 ; p = 0.0074) were risk factors for high values of aqueous flare at 2 weeks after surgery. CONCLUSIONS: Combined phacoemulsification does not enhance postoperative aqueous flare in trabeculectomy. Exfoliation glaucoma and postoperative shallow anterior chamber are factors in the elevation of aqueous flare.

Prognostic risk factors for failure of trabeculectomy with mitomycin C after vitrectomy.

PURPOSE: To evaluate the prognostic risk factors for failure of trabeculectomy with mitomycin C (MMC) in vitrectomized eyes. METHODS: Retrospective cohort study. We reviewed the medical records of 116 patients (116 eyes) treated at Kumamoto University Hospital. The primary endpoints were persistent intraocular pressure of >21 mmHg, deterioration of visual acuity to no light perception, or additional glaucoma procedures. Multivariable analysis was performed with the Cox proportional hazards model. RESULTS: The mean follow-up period was 36.5 months (range, 0.5-134.1 months). The probability of success 1 year after trabeculectomy was 55.1 %, 2 years after was 45.3 %, and 3 years after was 43.1 %. The multivariable model showed that higher preoperative intraocular pressure (IOP) [relative risk (RR), 1.05/mmHg; P = 0.0077] and neovascular glaucoma (NVG) (RR, 1.88; P = 0.049) were prognostic factors for surgical failure. CONCLUSIONS: The prognostic factors for surgical failure of trabeculectomy with MMC in vitrectomized eyes are a higher preoperative IOP and NVG.

Impact of phacoemulsification on failure of trabeculectomy with mitomycin-C.

PURPOSE: To evaluate whether phacoemulsification after trabeculectomy affects postoperative intraocular pressure (IOP). SETTING: Kumamoto University, Kumamoto, Japan. DESIGN: Cohort study. METHODS: The medical records of patients with primary open-angle glaucoma or exfoliation glaucoma who had trabeculectomy with mitomycin-C were reviewed. The primary endpoints were condition A (persistent postoperative IOP 21 mm Hg or higher or additional glaucoma procedures with or without medications) and condition B (postoperative IOP 18 mm Hg or higher or additional glaucoma procedures with or without medications). Multivariable analysis was performed using the Cox proportional hazards model. RESULTS: The records of 178 patients (178 eyes) were reviewed. The mean follow-up was 37.0 months. For condition A, the probability of treatment success at 1 year, 2 years, and 3 years was 97.9%, 95.0%, and 92.7%, respectively. For condition B, the corresponding probabilities of success were 92.3%, 84.1%, and 81.8%. Thirty-seven patients (37 eyes) had phacoemulsification after trabeculectomy; 10 of those patients had phacoemulsification within 1 year after trabeculectomy. Multivariate analysis showed that a higher IOP before trabeculectomy was a significant risk factor for condition A and condition B (P=.01 and P=.0006, respectively); phacoemulsification within 1 year after trabeculectomy was significantly associated with trabeculectomy failure for condition B (P=.04). CONCLUSION: Postoperative IOP in eyes with previous trabeculectomy may be affected by the IOP before trabeculectomy and phacoemulsification within 1 year after trabeculectomy. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Heparan sulfate regulates intraretinal axon pathfinding by retinal ganglion cells.

PURPOSE. Heparan sulfate (HS) is abundantly expressed in the developing neural retina; however, its role in the intraretinal axon guidance of retinal ganglion cells (RGCs) remains unclear. In this study, the authors examined whether HS was essential for the axon guidance of RGCs toward the optic nerve head. METHODS. The authors conditionally ablated the gene encoding the exostosin-1 (Ext1) enzyme, using the dickkopf homolog 3 (Dkk3)-Cre transgene, which disrupted HS expression in the mouse retina during directed pathfinding by RGC axons toward the optic nerve head. In situ hybridization, immunohistochemistry, DiI tracing, binding assay, and retinal explant assays were performed to evaluate the phenotypes of the mutants and the roles of HS in intraretinal axon guidance. RESULTS. Despite no gross abnormality in RGC distribution, the mutant RGC axons exhibited severe intraretinal guidance errors, including optic nerve hypoplasia, ectopic axon penetration through the full thickness of the neural retina and into the subretinal space, and disturbance of the centrifugal projection of RGC axons toward the optic nerve head. These abnormal phenotypes shared similarities with the RGC axon misguidance caused by mutations of genes encoding Netrin-1 and Slit-1/2. Explant assays revealed that the mutant RGCs exhibited disturbed Netrin-1-dependent axon outgrowth and Slit-2-dependent repulsion. CONCLUSIONS. The present study demonstrated that RGC axon projection toward the optic nerve head requires the expression of HS in the neural retina, suggesting that HS in the retina functions as an essential modulator of Netrin-1 and Slit-mediated intraretinal RGC axon guidance.

Trabeculectomy with mitomycin for open-angle glaucoma in phakic vs pseudophakic eyes after phacoemulsification.

OBJECTIVE: To determine whether previous phacoemulsification adversely affects surgical prognosis of trabeculectomy with mitomycin for open-angle glaucoma. METHODS: The study is a retrospective, consecutive, comparative case series. At 2 clinical centers, we reviewed 226 medical records of eyes with open-angle glaucoma undergoing initial trabeculectomy, including 175 phakic eyes (phakic group) and 51 pseudophakic eyes that had previously undergone phacoemulsification with superior conjunctival incision (pseudophakic group). Primary outcome was the probability of success after trabeculectomy. Surgical failure was defined as an additional glaucoma surgery or 1 of the following 3 criteria: intraocular pressure (IOP) of 21 mm Hg or greater (A); IOP of 18 mm Hg or greater (B); and IOP of 15 mm Hg or greater (C). Multivariable analysis was performed using the Cox proportional hazards model. RESULTS: The mean follow-up period was 37.5 months. The probability of success for criteria A, B, and C at 1 and 3 years in the phakic vs the pseudophakic group was 97.8% and 92.6%, respectively, vs 78.6% and 65.1%, respectively, for criterion A (P < .001); 92.9% and 81.3%, respectively, vs 72.8% and 63.7%, respectively, for criterion B (P = .004); and 73.1% and 54.2%, respectively, vs 53.1% and 38.4%, respectively, for criterion C (P = .009). The multivariable model confirmed that pseudophakia independently contributes to surgical failure (criterion A relative risk, 4.59 [P < .001]; criterion B, 2.88 [P = .004]; and criterion C, 2.02 [P = .009]). The pseudophakic group required more postoperative laser suture lysis (P = .01). CONCLUSION: Previous phacoemulsification is a prognostic factor for surgical failure of trabeculectomy with mitomycin for open-angle glaucoma.

Dynamic imaging of axonal transport in living retinal ganglion cells in vitro.

PURPOSE: Disruption of the axonal transport of neurotrophic factors plays a critical role in the apoptosis of retinal ganglion cells (RGCs) in glaucomatous optic neuropathy. Live-cell imaging in vitro was used in this study, to visualize and evaluate the axonal transport of brain-derived neurotrophic factor (BDNF) in both living and axon-damaged RGCs. METHODS: Rat RGCs were purified by a two-step immunopanning method. Cultivated RGCs were transfected with a plasmid encoding BDNF tagged with green fluorescent protein (GFP), and the dynamics of BDNF-GFP in the axons and dendrites were analyzed by time-lapse imaging. Changes in the axonal transport of BDNF-GFP were examined after treatment with 1 mM colchicine, and RGC death after treatment was evaluated with ethidium homodimer-1. RESULTS: The expression of BDNF-GFP showed a vesicular pattern in the axons and dendrites of cultivated RGCs. Time-lapse imaging revealed that the mean velocity of BDNF-GFP in the axons (0.86 ± 0.37 µm/s; maximum = 2.03 µm/s) was significantly greater (P < 0.0001) than that in the dendrites (mean = 0.49 ± 0.19 µm/s). Colchicine significantly inhibited the axonal transport of BDNF-GFP at 2 and 3 hours after treatment (P = 0.003 and 0.0002, respectively) without affecting cell viability; however, RGC death was detected 24 hours after treatment. CONCLUSIONS: Live-cell imaging revealed the dynamics of the axonal transport of BDNF in living RGCs, which clearly differed from the movements in dendrites. Furthermore, it was possible to confirm the disruption of axonal transport in colchicine-treated RGCs before cell death.

Combined intravitreal bevacizumab and trabeculectomy with mitomycin C versus trabeculectomy with mitomycin C alone for neovascular glaucoma.

PURPOSE: To evaluate the effects of intravitreal bevacizumab (IVB) before mitomycin C trabeculectomy (MMCT) for neovascular glaucoma (NVG). METHODS: The study is a retrospective, comparative, consecutive case series. The study group consisted of 57 eyes from 50 patients with NVG who underwent a first MMCT: 33 eyes were treated with MMCT alone between June 1, 2005 and May 17, 2007 (Control Group); and, 24 eyes were treated with a combination of IVB and MMCT after May 18, 2007 (IVB Group). Surgical complications, intraocular pressure (IOP), and the probability of success were compared between the 2 groups. Surgical failure was defined as IOP ≥22 mm Hg for 2 consecutive follow-up visits, a deterioration of visual acuity to no light perception, or additional glaucoma surgeries. RESULTS: There were no significant differences in preoperative data between the groups. Hyphema associated with MMCT occurred significantly less often in the IVB Group (P=0.006). IOPs at 7 and 10 days after MMCT were significantly lower in the IVB Group (P=0.01 and 0.02, respectively). However, Kaplan-Meier survival-curve analysis showed the probability of success 120, 240, and 360 days after MMCT of 87.5%, 79.2%, and 65.2% in the IVB Group, and 75.0%, 71.9%, and 65.3% in the Control Group. No significant difference in survival times was found between the groups (P=0.76). CONCLUSIONS: IVB before MMCT reduced hyphema associated with MMCT for NVG. IVB provided further IOP reduction immediately after MMCT, but did not significantly improve surgical outcomes over longer periods.

Heparan sulfate deficiency in periocular mesenchyme causes microphthalmia and ciliary body dysgenesis.

The heparan sulfate (HS) is a component of proteoglycans in the extracellular matrix and on cell surfaces, modulating developmental processes. The aim of this study is to investigate whether the defect of HS in the periocular mesenchyme impairs ocular morphogenesis. First, using Protein 0-Cre transgenic mice, we ablated Ext1, which encodes an indispensable enzyme for HS synthesis, in the developing periocular mesenchyme. The expression of Ext1 messenger RNA (mRNA) and HS were observed by RT-PCR and immunohistochemistry, respectively. The phenotypes in the mutant were evaluated by light microscopy and immunohistochemistry for cellular makers. Second, the distribution of the mutant periocular mesenchymal cells was tracked using a Rosa26 Cre-reporter gene. No mutant embryos (Protein 0-Cre;Ext1(flox/flox)) were identified after embryonic day 14.5 (E14.5). RT-PCR showed that an intense band amplified from Ext1 was observed in cDNAs from the control periocular mesenchymal cells at E13.5; however, the band for Ext1 was hardly detectable in cDNA from the mutant embryo, indicating that the mRNA was missing in the mutant periocular mesenchyme at E13.5. The HS expression was disrupted in the periocular mesenchyme of the mutant ocular tissues. The HS deficiency resulted in microphthalmia with reduced axial lengths, lens diameters, and vitreous sizes compared with the littermate eyes. The mutant embryos showed agenesis of the anterior chamber, where cells expressing Cre recombinase were distributed. Moreover, the mutants showed phenotypic alterations in the neural ectoderm including dysgenesis of the presumptive ciliary body and agenesis of the optic nerve head. These findings demonstrate that HS in the periocular mesenchyme plays a critical role in normal ocular morphogenesis, indicating reciprocal interactions between the periocular mesenchyme and the neural ectoderm.

Heparan sulfate deficiency leads to Peters anomaly in mice by disturbing neural crest TGF-beta2 signaling.

During human embryogenesis, neural crest cells migrate to the anterior chamber of the eye and then differentiate into the inner layers of the cornea, the iridocorneal angle, and the anterior portion of the iris. When proper development does not occur, this causes iridocorneal angle dysgenesis and intraocular pressure (IOP) elevation, which ultimately results in developmental glaucoma. Here, we show that heparan sulfate (HS) deficiency in mouse neural crest cells causes anterior chamber dysgenesis, including corneal endothelium defects, corneal stroma hypoplasia, and iridocorneal angle dysgenesis. These dysfunctions are phenotypes of the human developmental glaucoma, Peters anomaly. In the neural crest cells of mice embryos, disruption of the gene encoding exostosin 1 (Ext1), which is an indispensable enzyme for HS synthesis, resulted in disturbed TGF-beta2 signaling. This led to reduced phosphorylation of Smad2 and downregulated expression of forkhead box C1 (Foxc1) and paired-like homeodomain transcription factor 2 (Pitx2), transcription factors that have been identified as the causative genes for developmental glaucoma. Furthermore, impaired interactions between HS and TGF-beta2 induced developmental glaucoma, which was manifested as an IOP elevation caused by iridocorneal angle dysgenesis. These findings suggest that HS is necessary for neural crest cells to form the anterior chamber via TGF-beta2 signaling. Disturbances of HS synthesis might therefore contribute to the pathology of developmental glaucoma.

Trabeculectomy with mitomycin C for neovascular glaucoma: prognostic factors for surgical failure.

PURPOSE: To evaluate the prognostic factors for surgical outcomes of trabeculectomy with mitomycin C (MMC) for neovascular glaucoma (NVG). DESIGN: Retrospective cohort study. METHODS: We reviewed the medical records of 101 patients (101 eyes) with NVG treated at Kumamoto University Hospital. The primary endpoint was persistent intraocular pressure > or = 22 mm Hg, deterioration of visual acuity to no light perception, and additional glaucoma procedures. Multivariate analysis was performed using the Cox proportional hazards model. RESULTS: The mean follow-up period was 29.3 months (range, 0.5 to 142.3 months). The probability of success 1, 2, and 5 years after trabeculectomy was 62.6%, 58.2%, and 51.7%, respectively. The multivariate model showed that younger age (relative risk [RR], 0.96/year; P = .0007) and previous vitrectomy (RR, 1.62; P = .02) were prognostic factors for surgical failure among all NVG patients. Additionally, an eye with unremoved proliferative membrane and/or unrepaired retinal detachment (RD) after vitrectomy (RR, 1.59; P = .05) was a probable prognostic factor in a subgroup of 66 eyes with previous vitrectomy, and having a fellow eye with NVG (RR, 1.73; P = .003) was a significant prognostic factor in 82 eyes with NVG attributable to diabetic retinopathy. CONCLUSIONS: The prognostic factors for surgical failure of trabeculectomy with MMC for NVG were younger age and previous vitrectomy in all NVG patients, and having a fellow eye with NVG in patients with disease caused by diabetic retinopathy. Persistent proliferative membrane and/or RD after vitrectomy might contribute to poorer outcomes of trabeculectomy.

Restricted post-trabeculectomy bleb formation by conjunctival scarring.

PURPOSE: To evaluate the effects of radial conjunctival incision during fornix-based trabeculectomy, and conjunctival scarring associated with previous ocular surgeries, for the restriction of bleb formation. METHODS: Digital photo-slit lamp images of filtering blebs, which had undergone fornix-based trabeculectomy with mitomycin C previously, were analysed. The area and the height of the bleb in the conjunctivae with radial incision (Ain and Hin, respectively) were compared with the area and the height of the bleb in the conjunctivae without radial incision (Ano and Hno, respectively). We compared the parameters of bleb area (total bleb area, Ain and Ano) and bleb height (the bleb height at the centre of the scleral flap; Hc, Hin and Hno) in eyes without previous ocular surgeries, with those in eyes that underwent previous ocular surgeries. RESULTS: The study population consisted of 51 eyes. The Ano and the Hno were significantly larger than the Ain (p < 0.001) and the Hin (p < 0.001) respectively. Subgroup analyses in eyes without previous ocular surgeries and eyes with phacoemulsification cataract surgery also showed that the Ano was significantly larger than the Ain. However, there was no significant difference between the Ano and the Ain in eyes with previous trabeculectomy. A comparison of bleb formation between eyes without previous ocular surgeries and eyes with cataract surgery showed no significant differences in each of the bleb area and bleb height parameters. By contrast, the total bleb area (p = 0.021), the Ano (p = 0.017) and the Hc (p = 0.045) were significantly smaller in eyes with previous trabeculectomy than in eyes without previous ocular surgeries. CONCLUSIONS: Our data demonstrate that bleb formation depends on radial conjunctival incision during fornix-based trabeculectomy and surgical conjunctival scarring from previous trabeculectomy.

Long-term relationship between intraocular pressure and visual field loss in primary open-angle glaucoma.

PURPOSE: To investigate the dependence upon intraocular pressure (IOP) of the progression of visual field defects in eyes with primary open-angle glaucoma (POAG), in which the mean IOP was maintained at < or =21 mm Hg. METHODS: This study involved 100 eyes with POAG, which were followed up for > or =5 years. The mean IOP levels were maintained at < or =21 mm Hg during the follow-up period. The relationship between the IOP and the progression of visual field defects, which was scored using the Advanced Glaucoma Intervention Study criteria, was investigated retrospectively. RESULTS: Compared with the baseline scores, the visual field defect scores had significantly worsened by the end of the follow-up period (P<0.0001, Wilcoxon paired signed rank test). The change in the visual field defect score (2.5+/-0.5) in eyes with average IOP levels of > or =16 mm Hg (n=36) was significantly greater (P=0.031, Mann-Whitney U test) than the change (1.3+/-0.3) in eyes with average IOP levels of <16 mm Hg (n=64). Moreover, IOP of > or =18 mm Hg made a major contribution to the aggravation of visual field defects in eyes with POAG. CONCLUSIONS: Eyes with POAG and with mean IOP levels maintained at < or =21 mm Hg underwent IOP-dependent progression of their visual field defects. Our results suggest that further IOP lowering would be beneficial in such cases.