Otago Glaucoma Surgery Outcome Study

Juvenile-onset open-angle glaucoma - A clinical and genetic update

Juvenile-onset open-angle glaucoma (JOAG) is a subset of primary open-angle glaucoma that is diagnosed before 40 years of age. The disease may be familial or non-familial, with proportions varying among different populations. Myocilin mutations are the most commonly associated. JOAG is characterized by high intraocular pressures (IOP), with many patients needing surgery. The mean age at diagnosis is in the 3rd decade, with a male preponderance. Myopia is a common association. The pathophysiology underlying the disease is immaturity of the conventional outflow pathways, which may or may not be observed on gonioscopy and anterior segment optical coherence tomography. The unique optic nerve head features include large discs with deep, steep cupping associated with high IOP-induced damage. Progression rates among JOAG patients are comparable to adult primary glaucomas, but as the disease affects younger patients, the projected disability from this disease is higher. Early diagnosis, prompt management, and life-long monitoring play an important role in preventing disease progression. Gene-based therapies currently under investigation offer future hope.

The surgical management of glaucoma: A review

After a long period of little change, glaucoma surgery has experienced a dramatic rise in the number of possible procedures in the last two decades. Glaucoma filtering surgeries with mitomycin C and glaucoma drainage devices remain the standard of surgical care. Other newer surgeries, some of which are minimally or microinvasive glaucoma surgeries, target existing trabecular outflow, enhance suprachoroidal outflow, create subconjunctival blebs, or reduce aqueous production. Some require the implantation of a device such as the iStent, Hydrus, Ex-PRESS, XEN and PRESERFLO, whilst others do not-Trabectome, Kahook dual blade, Ab interno canaloplasty, gonioscopy-assisted transluminal trabeculotomy, OMNI and excimer laser trabeculotomy. Others are a less destructive variation of an established procedure, such as micropulse transscleral cyclophotocoagulation, endoscopic cyclophotocoagulation and ultrasound cycloplasty. Cataract surgery alone can be a significant glaucoma operation. These older and newer glaucoma surgeries, their mechanism of action, efficacy and complications are the subject of this review.

Ahmed and Baerveldt Drainage Implants in the Treatment of Juvenile Open-angle Glaucoma

PRECIS

Ahmed and Baerveldt implants succeed in 90.7% of cases for lowering intraocular pressure (IOP) <21 mm Hg at 1 year when used for the treatment of juvenile open-angle glaucoma.

PURPOSE

The purpose of this study was to report the 1-year outcomes of Ahmed and Baerveldt tubes as the treatment for juvenile open-angle glaucoma at an academic institution.

PATIENTS AND METHODS

Patients 18 to 40 years of age at the time of juvenile open-angle glaucoma diagnosis, who had inadequately controlled glaucoma with an IOP of 18 mm Hg or more on maximum tolerated antiglaucoma therapy that underwent tube shunt surgery with at least 6 months of follow-up were eligible for the study. Exclusion criteria included evidence of neovascular, uveitic or inflammatory, steroid-induced or primary congenital glaucoma, or if they did not have light perception vision. Postoperative failure was defined as an IOP, with or without antiglaucoma drops, >21 mm Hg for 2 consecutive visits after 3 months from surgery, <20% decrease in IOP at 1 year, no light perception, or revision of an implant due to high IOP.

RESULTS

The study population included 32 eyes from 25 patients who underwent tube shunt surgery. The failure rate at 1-year follow-up was 9.3%, and the postoperative complication rate at 1-year follow-up was 9.3%. The average change from baseline to 1 year for IOP was a decrease of 9.8±9.10, for the number of antiglaucoma drops number was a decrease of 0.38±1.06, and for the visual acuity was an increase of 0.03±0.27.

CONCLUSIONS

Ahmed and Baerveldt implantation succeeded in lower IOP in 90.7% of patients at 1 year. Continuation of antiglaucoma drops to maintain the IOP after surgery is likely required.

Risk Factors for Failure in Double-Plate Tube Surgery for Refractory Glaucoma: 25 Years Surgical Experience

Purpose

To investigate risk factors associated with success and failure in double-plate tube surgery.

Methods

This retrospective case-series observational study included 243 consecutive eyes that underwent anterior-segment double-plate tube surgery from 1990 to 2015. Evaluation of the efficacy of the device was based on the final intraocular pressure (IOP) and the need for anti-glaucoma medication. We also assessed success and failure according to risk factors for trabeculectomy and an early hypertensive phase (HP).

Results

Preoperative IOP was 37.3±13.1 mmHg (mean±SD) with 3.0±0.7 medications. After a median follow-up of 44.3 months, the mean IOP was 14.6±6.3 mmHg with 0.4±1.0 medications. The final IOPs ranged from 6 to 21 mmHg in 87.24% of eyes; however, 25.47% required medication. No risk factors studied were associated with surgical failure. Preoperative IOP, glaucoma type, previous surgery, previous anti-glaucoma drugs, implant type, and HP were associated with partial success (p<0.05). HP and preoperative use of brimonidine reduced the probability of complete success by 66.9% and 68.2%, respectively (p<0.05). HP was more likely when chronic preoperative prostaglandin analogues were administered (odds ratio [OR] 4.286; 95% confidence intervals [CI] 1.593–11.529; P=0.0039) and when the tube was located in the posterior chamber (OR 3.561; 95% CI 1.286–9.861; P=0.0145).

Conclusion

Tube surgery is effective and seems to be independent of the major risk factors for glaucoma surgery. However, previous surgery and some chronic preoperative drugs are related to the need for glaucoma medication to achieve the target pressure.

The Effects of Glaucoma Drainage Devices on Oxygen Tension, Glycolytic Metabolites, and Metabolomics Profile of Aqueous Humor in the Rabbit

PURPOSE

Glaucoma drainage device (GDD) implantation can lead to corneal decompensation. We evaluated changes over time in oxygen tension and in the metabolic environment of the aqueous humor after GDD implantation in the rabbit eye.

METHODS

Ahmed Glaucoma Valves were implanted in the left eyes of eight male New Zealand white rabbits. Right eyes were used as a control. Oxygen tension was measured immediately before surgery and at 1 and 2 months postoperation. Aqueous humor was collected from the surgical and control eyes at 1, 2, and 5 months postoperation. Aqueous humor samples collected at 1 and 5 months postoperation were selected for broad-spectrum metabolomics analysis using ultra-performance liquid chromatography-time of flight-mass spectrometry (UPLC TOF-MS). Multivariate analysis methods were used to identify metabolite profiles that separated the surgical and control eye at 1 and 5 months.

RESULTS

There was a significant decrease in oxygen tension in aqueous humor of the surgical eyes (9 mm Hg, 95% confidence interval [CI]: -14.7 to -3.5). Differences in the metabolic profiles between the surgical and control eye at 1 and 5 months were observed, as were differences for the surgical eye at 1 and 5 months. In addition, a metabolite profile was identified that differentiated the surgical eyes at 1 and 5 months.

CONCLUSION

Changes in the oxygen tension and metabolic intermediates occur within the aqueous humor as early as 1 month after GDD implantation.

TRANSLATIONAL RELEVANCE

Corneal decompensation following GDD implantation could be secondary to disruption of the normal aqueous circulation, resulting in hypoxia and an altered metabolic profile. Alterations to the GDD design might minimize aqueous disruption and prevent corneal decompensation.

Achieving Target Pressures with Combined Surgery: Primary Patchless Ahmed Valve Combined with Phacoemulsification vs Primary Phacotrabeculectomy

PURPOSE

To evaluate the ability of phacoemulsification combined with either primary trabeculectomy (PT) or primary Ahmed glaucoma valve implantation (PAVI) to achieve target intraocular pressures (TIOP) in adults with primary open angle glaucoma.

MATERIALS AND METHODS

Chart review of 214 adult patients operated between January 2002 and June 2008 with a minimum follow-up of 6 months. Group 1 comprised 181 eyes of 166 patients undergoing PT while group 2 included 50 eyes of 49 patients in combination with primary AVI. Target lOPs were pre-determined for each patient and success was defined as an IOP at or lower than target with or without medications. An IOP above target, loss of light perception or need for additional procedures to lower IOP were considered a failure.

RESULTS

Mean preoperative IOP was 17.2 mm Hg in group 1 and 17.3 in group 2. Mean postoperative IOPs were 10.2 and 9.2 on day 1, 12.2 and 11.6 at year 1, and 10.7 in both groups at year 5. Survival rates in groups 1 and 2 were 96.7 vs 96% at 6 months, 89 vs 96% at 12 months, 83.5 vs 96% at 24 months and 79.4 vs 89.1% at 36, 48 and 72 months. Transient bleb leaks were more frequent in group 1 (26 eyes, 14.4 vs 0%, p = 0.001) and transient choroidal detachments were more frequent in group 2 (7 eyes, 3.9 vs 6 eyes, 12%, p = 0.038).

CONCLUSION

Midterm results for achieving target pressures using combined phacoemulsification with either PT or PAVI are comparable. The profile of complications is different for the two procedures. How to cite this article: Albis-Donado O, Sánchez-Noguera CC, Cárdenas-Gómez L, Castañeda-Diez R, Thomas R, Gil-Carrasco F. Achieving Target Pressures with Combined Surgery: Primary Patchless Ahmed Valve Combined with Phacoemulsification vs Primary Phacotrabeculectomy. J Curr Glaucoma Pract 2015;9(1):6-11.

Combined Baerveldt glaucoma implant and scleral buckling surgery for patients with retinal detachment and coexisting glaucoma

PURPOSE

To report on the usefulness of combined Baerveldt glaucoma implantation (BGI) and scleral buckling surgery for patients with glaucoma requiring a scleral buckle for retinal detachment repair.

METHODS

Retrospective, consecutive, noncomparative, and interventional case series of 30 eyes (30 patients) that underwent simultaneous scleral buckle and BGI surgery, using a staged (group 1, n=21 patients) or nonstaged (group 2, n=9 patients) approach to BGI implantation. Successful intraocular pressure (IOP) control was defined as 6 mm Hg≤IOP≤18 mm Hg.

RESULTS

Although not statistically significant, mean best corrected visual acuity (LogMAR) improved from 2.0 before surgery to 1.7 after surgery (P=0.13) with a mean follow-up of 27.7 months. Of the 21 patients in group 1, only 13 (62%) required second-stage tube insertion at a mean of 7.0±8.0 months (range, 1 to 24 mo) postoperatively. For these eyes combined with group 2 eyes, mean IOP was reduced from 31.1±10.8 to 12.7±6.0 mm Hg (P<0.0001), and the mean number of glaucoma medications was reduced from 2.9±1.4 to 1.2±1.3 (P<0.001). Life table rates of successful IOP control were 90% and 80% at 12 and 24 months, respectively.

CONCLUSIONS

Combined scleral buckle and BGI is an effective technique for managing coexisting glaucoma and retinal detachment and provides the clinician with a useful surgical option while minimizing surgical risk.

Adjunctive bevacizumab in patients undergoing Ahmed valve implantation: a pilot study

BACKGROUND AND OBJECTIVE

To report on preliminary findings of adjunctive subconjunctival bevacizumab (SCB) injections in patients undergoing Ahmed valve implantation (AVI) (New World Medical, Rancho Cucamonga, CA).

PATIENTS AND METHODS

The study was approved by the institution's ethics committee. Patients were prospectively recruited during a 1-month period and randomized to receive AVI with postoperative SCB (days 1 and 7, n = 7) or AVI without SCB (n = 6).

RESULTS

Baseline intraocular pressure (IOP) in the treatment (AVI+SCB) group was 19.4 ± 8.6 mm Hg, whereas baseline IOP in the control (AVI) group was 32.1 ± 17.7 mm Hg (P = .119). Final IOP was 13.8 mm Hg (n = 7) for the treatment group and 12.7 mm Hg for the control group (n = 5, P = .790). One eye in the control group required further glaucoma intervention at day 45 and was considered a failure. The pre-massage postoperative IOP was significantly lower for the treatment group only at day 45 (16.1 vs 26.0 mm Hg, P = .012). Mean post-massage IOP was significantly lower in the treatment group at day 15 (11.28 vs 17.16 mm Hg, P = .004), day 30 (11.28 vs 20.83 mm Hg, P = .015), and day 45 (12.16 vs 21.33 mm Hg, P = .001), and similar at month 3. Mean change in bleb area was 11.4 mm(2) in the treatment group and -0.4 mm(2) in the control group (P = .036 and P = .361, respectively, Student's paired samples t test).

CONCLUSION

Bevacizumab was associated with a less aggressive hypertensive period as measured by post-massage IOP measurements, postoperative glaucoma medications, and cross-sectional bleb area by ultrasound. Further prospective studies are needed to better understand the utility of SCB at the time of AVI surgery.

Evaluation of Ahmed glaucoma valve implantation through a needle-generated scleral tunnel in Mexican children with glaucoma

Purpose:

To evaluate the results and extrusion rates of the Ahmed glaucoma valve (AGV) implantation through a needle-generated scleral tunnel, without a tube-covering patch, in children.

Materials and Methods:

A retrospective review of the charts of 106 Mexican children implanted with 128 AGVs operated between 1994 and 2002, with the needle track technique, at our institution, with at least six months follow up was done. Main outcome measures were intraocular pressure (IOP) control, tube extrusions or exposure and other complications.

Results:

Kaplan-Meier analysis demonstrated a 96.9% survival rate at six months, 82.4% at one year, 78.7% at two years, 70% at three years and 41.6% at four years. Total success at the last follow-up (IOP between 6 and 21 mm Hg without medications) was achieved in 30 eyes (23.5%), 58 eyes (45.3%) had qualified success (only topical hypotensive drugs) and 40 eyes (31.3%) were failures. The mean pre- and post-operative IOP at the last follow up was 28.4 mmHg (SD 9.3) and 14.5 mmHg (SD 6.3), respectively. No tube extrusions or exposures were observed. Tube-related complications included five retractions, a lens touch and a transitory endothelial touch. The risk of failure increased if the eye had any complication or previous glaucoma surgeries.

Conclusion:

Medium-term IOP control in Mexican children with glaucoma can be achieved with AGV implantation using a needle-generated tunnel, without constructing a scleral flap or using a patch to cover the tube. There were no tube extrusions, nor any tube exposures with this technique.

Glaucoma affects steady state VEP contrast thresholds before psychophysics

PURPOSE

Frequency doubling technology (FDT) is a recent psychophysical test for glaucoma. It measures the contrast threshold to low spatial frequency, high temporal frequency sinusoidal luminance profile bars. We wanted to confirm, with stricter controls, Vaegan and Hollow's report that contrast thresholds of steady state visual evoked potentials (ssVEPs) to a stimulus resembling the central field of the FDT test was more sensitive to glaucoma than the subjective threshold to the same stimulus and to start to optimize the technique.

METHODS

A double masked trial using 57 eyes of 42 subjects. Both thresholds were estimated by modified binary search. In psychophysical testing, subjects were given a two alternative forced choice task. In ssVEP testing a significant signal in any one of eight channels was deemed to be a detection. In some subjects electrode positions were compared, both eyes were tested, tests were repeated to estimate reliability, stimulus frequencies were varied or full contrast functions were obtained.

RESULTS

Thresholds and percent abnormal increased as a function of glaucoma severity for ssVEPs but not for psychophysics. Both threshold measures were reliable. Interocular correlations were low. SsVEP amplitude against contrast functions had similar thresholds to those found by modified binary search. The data was too irregular for individual thresholds to be estimated from a fitted exponential. Amplitudes were greatest at 7 to 10 Hz, < or =6 cm above inion and least laterally. Noise was similar across electrodes.

CONCLUSIONS

SsVEP contrast thresholds to a stimulus like the central field of the FDT test detected glaucoma better than corresponding psychophysical thresholds at 18.29 Hz, when formal controls were used, as they had in a less controlled previous study at 7.14 Hz.

Clinical and genetic characteristics of primary juvenile-onset open-angle glaucoma (JOAG)

Juvenile-onset open-angle glaucoma (JOAG) is an autosomal dominant disease characterized by an early age of onset and severely elevated intraocular pressures. Large JOAG pedigrees have been pivotal in genetic linkage analyses that have helped establish the association between JOAG and the myocilin gene (MYOC). Numerous disease-causing MYOC mutations have now been identified, and additional loci on other chromosomes have been linked to JOAG. Ongoing molecular genetic studies on myocilin and the search for new gene defects associated with JOAG may offer new directions in our scientific understanding and clinical management of open-angle glaucoma.

Long-term results of Molteno implant insertion in cases of chronic angle closure glaucoma

BACKGROUND

This study was undertaken to provide data on the long-term results of cases of chronic angle closure glaucoma with additional risk factors treated by Molteno implants between 1985 and 2004 at Dunedin Hospital, New Zealand.

METHODS

A prospective non-comparative case series followed 21 eyes (17 patients) for a mean of 5.7 years (range 1.3-16.3 years) in terms of intraocular pressure, visual acuity and subsequent procedures.

RESULTS

Insertion of a Molteno implant has controlled the intraocular pressure at 21 mmHg or less in 100% of cases at 5 years after surgery, the probability of control being 0.95 (95% CI 0.91-0.99). The mean number of hypotensive medications reduced from 2.04 (SD 0.92) preoperatively to 1.40, 0.64 and 0.66 at 1, 2 and 5 years, respectively. The mean visual acuity improved from 6/18 preoperatively to 6/12 at 1 year and declined to 6/13.5 at 2 and 5 years.

CONCLUSION

Insertion of Molteno implants was a safe and effective procedure in the management of complex cases of chronic angle closure glaucoma.