Direct selective laser trabeculoplasty in open angle glaucoma study design: a multicentre, randomised, controlled, investigator-masked trial (GLAUrious).

INTRODUCTION: Laser trabeculoplasty is an effective and widely used treatment for glaucoma. A new laser technology, the Eagle direct selective laser trabeculoplasty (DSLT) device, may provide automated, fast, simple, safe and effective laser treatment for glaucoma in a broader range of clinical settings. This trial aims to test the hypothesis that translimbal DSLT is effective and not inferior to selective laser trabeculoplasty (SLT) in reducing intraocular pressure (IOP) in open angle glaucoma (OAG). METHODS AND ANALYSIS: This is a multicentre, randomised, controlled, investigator-masked study. The primary efficacy outcome is intergroup difference in mean change from baseline IOP measured at 6 months. Secondary outcomes include mean percentage reduction in IOP at 3, 6 and 12 months; proportion of participants with at least 20% reduction in IOP from baseline at 6 months; change in ocular hypotensive medications at 12 months and evaluation of safety. Participants were aged >= 40 years with OAG, including exfoliative or pigmentary glaucoma, or ocular hypertension with untreated or washed out IOP 22-35 mm Hg. TREATMENTS: DSLT: 120 shots, 3 ns, 400 µm spot size, energy 1.4-1.8 mJ delivered at the limbus over 2 s. SLT: approximately 100 shots, 3 ns, 400 µm spot size administered 360 degrees at the limbus using any gonioscopy lens, energy 0.3-2.6 mJ. A sample size of 164 is sufficient to detect a non-inferiority margin of 1.95 mm Hg for change from baseline IOP. CLINICAL TRIAL REGISTRATION NUMBER: NCT03750201, ISRCTN14033075.

Effect of shunt type on rates of tube-cornea touch and corneal decompensation after tube shunt surgery in uveitic glaucoma.

PURPOSE: To evaluate the effect of tube shunt type [Ahmed (AGV) versus Baerveldt (BGI)] on the frequency of tube-cornea touch and corneal decompensation after tube shunt surgery. METHODS: This retrospective comparative study included 145 eyes of 130 patients with uveitic glaucoma who underwent AGV (75 eyes) or BGI (70 eyes) implantations. Electronic medical records were reviewed to document demographic factors, intraocular pressure (IOP) reduction, frequency of tube-cornea touch, corneal decompensation, and need for subsequent corneal transplantation. RESULTS: The mean follow-up was 27.7±3.3 months for AGV and 32.8±3.8 months for BGI (p=0.30). Tube-cornea touch was observed in 5 eyes after BGI and 1 eye in the AGV group (p=0.08). The BGI group reported a significantly higher rate of corneal decompensation (9 versus 0; p=0.001) and transplantation (6 versus 0; p=0.01) compared to the AGV group. Previous trabeculectomy was a significant risk factor for corneal complications in eyes undergoing BGI implantation (odds ratio [OR]= 8.17, 95% confidence interval [CI]=1.78-37.45, p=0.007). CONCLUSION: Similar rates of tube-cornea touch were observed in both shunt types; BGI shunts were associated with a greater incidence of corneal complications and transplantation as compared to AGV in this retrospective series of uveitic glaucoma cases.

Outcomes of Valved and Nonvalved Tube Shunts in Neovascular Glaucoma.

PURPOSE: To determine the outcomes of Ahmed glaucoma valve (AGV; New World Medical Inc) and Baerveldt glaucoma implant (BGI; Advanced Medical Optics) surgery in the setting of neovascular glaucoma (NVG). DESIGN: Single-center, retrospective study. PARTICIPANTS: Consecutive patients who underwent AGV or BGI surgery for the treatment of NVG and had ≥6 months of follow-up. METHODS: Chart review of AGV and BGI surgical outcomes in patients with NVG. MAIN OUTCOME MEASURES: Progression to no light perception (NLP) vision and 6-month surgical failure, which was defined as intraocular pressure (IOP) >21 mmHg with medications or <5 mmHg at 2 consecutive visits, or glaucoma reoperation. RESULTS: A total of 152 eyes (91 AGV, 61 BGI) were included with an average follow-up of 29.6 ± 25.8 months. Baseline demographics and clinical characteristics were comparable between groups. At month 6, failure was similar between AGV and BGI eyes (21.6% vs. 25.9%; P = 0.552), but glaucoma medication use was lower in BGI eyes (P < 0.001). At the final visit, 18.7% of AGV and 14.8% of BGI eyes progressed to NLP vision (P = 0.530), and medication use was lower in BGI eyes (P < 0.0001). Multivariate analysis identified lower preoperative visual acuity (VA) (P = 0.001), failure to receive panretinal photocoagulation within 2 weeks of surgery (P = 0.003), and bilaterality of the underlying ischemic retinal pathology (P = 0.026) as the strongest predictors of NLP outcome. Age, sex, race, NVG etiology, tube type, preoperative IOP, extent of synechial angle closure preoperatively, preoperative hyphema, IOP at the first NLP visit, and final IOP were not significant predictors of NLP vision. CONCLUSIONS: Eyes with AGV and BGI had comparable outcomes in NVG, although fewer medications were required in BGI eyes to control IOP. Progression to NLP vision was associated with poor baseline VA, delayed retinal treatment, and bilaterality of the underlying ischemic retinal pathology.

Reproducibility of minimum rim width and retinal nerve fibre layer thickness using the Anatomic Positioning System in glaucoma patients.

OBJECTIVE: To determine the test-retest repeatability of minimum rim width and retinal nerve fibre layer thickness measurements obtained by spectral-domain optical coherence tomography using the Anatomic Positioning System protocol in glaucoma patients and controls. Also, to assess the ability of the minimum rim width and retinal nerve fibre layer thickness to diagnose glaucoma in 2 circular peripapillary locations. METHODS: Spectral domain optical coherence tomography scans of the optic nerve head were obtained twice during the same visit using the Anatomic Positioning System eye-tracking protocol. The minimum rim width and retinal nerve fibre layer thickness were measured at 3 circular diameters (3.5 mm, 4.1 mm, and 4.7 mm). Intraclass correlation coefficients and area under the receiver operating characteristic were calculated for these parameters. RESULTS: A total of 36 glaucomatous eyes and 59 control eyes were included in the analysis. The intraclass correlation coefficients of minimum rim width and retinal nerve fibre layer thickness global measurement for 3.5 mm and 4.1 mm circles ranged between 0.98 and 1.00 and for 4.7 mm circle was between 0.76 and 1.00. The minimum rim width had an area under the receiver operating characteristic of 0.97, while the retinal nerve fibre layer thickness measurements had an area under the receiver operating characteristic of 0.95, 0.95, and 0.96 for the 3.5 mm, 4.1 mm, and 4.7 mm circles, respectively. CONCLUSIONS: The minimum rim width and retinal nerve fibre layer thickness measurements using the Anatomic Positioning System protocol had overall excellent reproducibility and diagnostic performance. Using this protocol and the novel minimum rim width parameter may be useful in more accurate diagnosis and follow-up of patients with glaucoma.

Awareness of ocular diagnosis, transportation means, and barriers to ophthalmology follow-up in the Philadelphia Telemedicine Glaucoma Detection and Follow-up Study.

Purpose: The purpose of this study was to assess factors affecting follow-up eye care in participants enrolled in the Philadelphia Telemedicine Glaucoma Detection and Follow-up Study, such as awareness of ocular diagnosis, availability of transportation methods, and reasons for missing eye care appointments. Methods: The sample included 172 participants who were randomized to the intervention group and contacted by the social worker. Results: A total of 155 participants completed the assessment form, which was used as an instrument to assess factors affecting adherence to follow-up eye care. The main reasons for missing eye exam appointments were feeling ill (38.1%, n = 59) and forgetting the appointment (34.2%, n = 53). In addition, 45 (29.2%) participants were unaware of or did not comprehend the severity of their ocular diagnosis. Common methods of transportation included public transportation (31.6%, n = 49), driving (29.7%, n = 46), and being driven (27.7%, n = 43) to their appointment. Conclusion: These results suggest that individuals in need of eye care may benefit from additional assistance of a social worker regarding ongoing eye exam appointment reminders and in-depth explanation of their ocular diagnosis.

Philadelphia Telemedicine Glaucoma Detection and Follow-up Study: confirmation between eye screening and comprehensive eye examination diagnoses.

AIMS: To evaluate agreement between ocular findings of a telemedicine eye screening (visit 1) with diagnoses of a comprehensive eye examination (visit 2). METHODS: A primary care practice (PCP)-based telemedicine screening programme incorporating fundus photography, intraocular pressure (IOP) and clinical information was conducted. Eligible individuals were African American, Hispanic/Latino or Asian over the age of 40; Caucasian individuals over age 65; and adults of any ethnicity over age 40 with a family history of glaucoma or diabetes. Participants with abnormal images or elevated IOP were invited back for a complete eye examination. Both visit 1 and visit 2 were conducted at participants' local PCP. Ocular findings at visit 1 and eye examination diagnoses at visit 2 are presented, including a cost analysis. RESULTS: Of 906 participants who attended visit 1, 536 were invited to visit 2 due to ocular findings or unreadable images. Among the 347 (64.9%) who attended visit 2, 280 (80.7%) were diagnosed with at least one ocular condition. Participants were predominately women (59.9%) and African American (65.6%), with a mean age (±SD) of 60.6±11.0 years. A high diagnostic confirmation rate (86.0%) was found between visit 1 and visit 2 for any ocular finding. Of 183 with suspicious nerves at visit 1, 143 (78.1%) were diagnosed as glaucoma or glaucoma suspects at visit 2. CONCLUSIONS: This screening model may be adapted and scaled nationally and internationally. Referral to an ophthalmologist is warranted if abnormal or unreadable fundus images are detected or IOP is >21 mm Hg. TRIAL REGISTRATION NUMBER: NCT02390245.

Vision-related Performance and Quality of Life of Patients With Rapid Glaucoma Progression.

PURPOSE: The purpose of this study was to determine how clinical measures, performance-based measures and subjective assessments of vision-related quality of life (VRQoL) are affected in patients with rapid glaucoma progression. METHODS: Prospective longitudinal study that included 153 patients diagnosed with moderate glaucoma. A subset of patients that presented with rapid glaucoma progression (n=22), defined as visual field (VF) mean deviation (MD) loss >2.0 dB/y, were compared with patients with nonrapid progression (n=131). Groups were compared using t tests, χ, or Fisher exact test. Main outcome measures were visual acuity (VA), VF MD, retinal nerve fiber layer thickness (RNFL), contrast sensitivity (CS), Compressed Assessment of Ability Related to Vision (CAARV), and Rasch calibrated National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) scores. RESULTS: At baseline, patients who progressed rapidly had lower measurements of VA (P=0.041), VF MD (P<0.001), Pelli-Robson score (P=0.004), Spaeth/Richman Contrast Sensitivity (SPARCS) score (P=0.001), RNFL thickness (P=0.009), CAARV total score (P<0.001), and NEI-VFQ-25 composite score (P=0.03). A multivariable logistic regression was performed and showed VF MD to be the only baseline independent predictor of rapid progression. After 1 year, patients who progressed rapidly also had a significant decrease in SPARCS score (P=0.04). CONCLUSIONS: Factors associated with rapid glaucoma progression included worse VF MD decreased scores of performance-based measures and subjectively worse VRQoL. After 1 year, rapid progressors had a significant reduction in contrast sensitivity as measured by SPARCS.

Validation of the structure-function correlation report from the heidelberg edge perimeter and spectral-domain optical coherence tomography.

PURPOSE: To compare the diagnostic assessment of glaucoma specialists with an automated structure-function correlation report combining visual field (VF) and spectral-domain optical coherence tomography (SD-OCT) imagining in subjects with glaucoma. METHODS: This prospective, cross-sectional study was conducted at Wills Eye Hospital, Philadelphia, PA, USA. Subjects with glaucoma received ophthalmic examination, VF testing, and SD-OCT imaging. An automated report was generated describing structure-function correlations between the two structural elements [retinal nerve fiber layer (RNFL) and Bruch's membrane opening-minimum rim width (MRW)] and VF sectors. Three glaucoma specialists masked to the automated report and to each other identified clinically significant structure-function correlations between the VF and SD-OCT reports. Raw agreement and chance-corrected agreement (kappa statistics) between the automated report and the clinical assessments were compared. RESULTS: A total of 53 eyes from 45 subjects with glaucoma were included in this study. The overall agreement between the automated report and clinical assessment comparing MRW and VF was good at 74.8% with a kappa of 0.62 (95% CI 0.55-0.69). Agreements for the six different MRW sections were moderate to good with kappa values ranging from 0.54 to 0.69. For mean RNFL thickness and VF comparisons, agreement between the automated report and clinical assessment was 75.4% with a kappa of 0.62 (95% CI 0.54-0.70). For different RNFL sectors, kappa values ranged from 0.47 (moderate agreement) to 0.80 (good agreement). CONCLUSIONS: This study suggests that the automated structure-function report combining results from the SD-OCT and the HEP may assist in the evaluation and management of glaucoma.

Impact of a Social Worker in a Glaucoma Eye Care Service: A Prospective Study.

The purpose of this study was to evaluate the effects of a six-month social worker intervention for participants with a glaucoma-related diagnosis in an urban ophthalmic setting (N = 40). The social worker assessed common barriers to eye care, helping participants with transportation, access to low-vision resources, and supportive counseling. The Distress Thermometer, Patient Health Questionnaire-9, and a satisfaction survey were administered to determine the effect of the social worker intervention and participants' overall impressions of the social worker. The most common barrier to eye care was emotional distress (77.5 percent). There was a significant decrease in the number of participants with symptoms of major and moderate depression. Fourteen participants experienced a clinically relevant decrease in depression, 37 participants felt that the social worker's support addressed their issues, and 29 participants thought it helped them in managing their glaucoma. This study provides evidence that a social work intervention may improve care coordination and management of individuals afflicted with vision impairment due to glaucoma and other ocular diseases.

Steady-state pattern electroretinogram and short-duration transient visual evoked potentials in glaucomatous and healthy eyes.

IMPORTANCE: This study evaluates two rapid electrophysiological glaucoma diagnostic tests that may add a functional perspective to glaucoma diagnosis. BACKGROUND: This study aimed to determine the ability of two office-based electrophysiological diagnostic tests, steady-state pattern electroretinogram and short-duration transient visual evoked potentials, to discern between glaucomatous and healthy eyes. DESIGN: This is a cross-sectional study in a hospital setting. PARTICIPANTS: Forty-one patients with glaucoma and 41 healthy volunteers participated in the study. METHODS: Steady-state pattern electroretinogram and short-duration transient visual evoked potential testing was conducted in glaucomatous and healthy eyes. A 64-bar-size stimulus with both a low-contrast and high-contrast setting was used to compare steady-state pattern electroretinogram parameters in both groups. A low-contrast and high-contrast checkerboard stimulus was used to measure short-duration transient visual evoked potential parameters in both groups. MAIN OUTCOME MEASURES: Steady-state pattern electroretinogram parameters compared were MagnitudeD, MagnitudeD/Magnitude ratio, and the signal-to-noise ratio. Short-duration transient visual evoked potential parameters compared were amplitude and latency. RESULTS: MagnitudeD was significantly lower in glaucoma patients when using a low-contrast (P = 0.001) and high-contrast (P < 0.001) 64-bar-size steady-state pattern electroretinogram stimulus. MagnitudeD/Magnitude ratio and SNR were significantly lower in the glaucoma group when using a high-contrast 64-bar-size stimulus (P < 0.001 and P = 0.010, respectively). Short-duration transient visual evoked potential amplitude and latency were not significantly different between the two groups. CONCLUSIONS AND RELEVANCE: Steady-state pattern electroretinogram was effectively able to discern between glaucomatous and healthy eyes. Steady-state pattern electroretinogram may thus have a role as a clinically useful electrophysiological diagnostic tool.

Evolution of optic nerve photography for glaucoma screening: a review.

Visual evaluation of the optic nerve has been one of the earliest and most widely used methods to evaluate patients for glaucoma. Photography has proven very useful for documentation of the nerve's appearance at a given time, allowing more detailed scrutiny then, and later comparison for change. Photography serves as the basis for real-time or non-simultaneous review in telemedicine and screening events allowing fundus and optic nerve evaluation by experts elsewhere. Expert evaluation of disc photographs has shown diagnostic performance similar to other methods of optic nerve evaluation for glaucoma. Newer technology has made optic nerve photography simpler, cheaper and more portable creating opportunities for broader utilization in screening in underserved populations by non-physicians. Recent investigations suggest that non-physicians or software algorithms for disc photograph evaluation have promise to allow more screening to be done with fewer experts.

Adherence to Follow-up Recommendations Among Individuals in the Philadelphia Glaucoma Detection and Treatment Project.

PURPOSE: To evaluate rates of adherence to free follow-up eye exam appointments among participants in the Philadelphia Glaucoma Detection and Treatment Project. PATIENTS AND METHODS: Ophthalmologists and testing equipment were brought directly to participants at risk for glaucoma at 43 community sites in Philadelphia. Those diagnosed with glaucoma-related pathology were recommended to return for follow-up to be reexamined on site. Rates of adherence and clinical and demographic risk factors for adherence were evaluated. RESULTS: Five hundred thirty-one participants were diagnosed with glaucoma-related conditions and recommended to attend community-based follow-up exams. Follow-up adherence rate was 61.2% (n=325/531). Significant factors associated with greater eye exam appointment adherence, based on our univariable analysis, included final diagnosis of glaucoma (risk ratio [RR]=1.33; 95% confidence interval [CI], 1.13-1.57), male sex (RR=1.19; 95% CI, 1.04-1.36), white race (RR=1.26; 95% CI, 1.08-1.48), age (RR=1.17; 95% CI, 1.00-1.37) recommendation for glaucoma medication (RR=1.52; 95% CI, 1.35-1.71), recommendation for laser peripheral iridotomy (RR=1.18; 95% CI, 1.02-1.35), diagnosis of age-related macular degeneration (RR=1.42; 95% CI, 1.13-1.77) and an increased intraocular pressure (>22 mm Hg in the worse eye) (RR=1.23; 95% CI, 1.06-1.42). On the basis of our multivariable model, diagnosis, sex, and recommended glaucoma medications were significantly associated with follow-up adherence. CONCLUSIONS: This study demonstrates that individuals living in underserved urban communities would take advantage of free eye exams in community sites and return for follow-up eye exams in these same settings. Future studies could investigate interventions to improve eye exam appointment adherence in community-based settings to detect glaucoma-eye conditions.

Philadelphia Telemedicine Glaucoma Detection and Follow-up Study: Methods and Screening Results.

PURPOSE: To describe methodology and screening results from the Philadelphia Telemedicine Glaucoma Detection and Follow-up Study. DESIGN: Screening program results for a prospective randomized clinical trial. METHODS: Individuals were recruited who were African-American, Hispanic/Latino, or Asian over age 40 years; white individuals over age 65 years; and any ethnicity over age 40 years with a family history of glaucoma or diabetes. Primary care offices and Federally Qualified Health Centers were used for telemedicine (Visit 1). Two posterior fundus photographs and 1 anterior segment photograph were captured per eye in each participant, using a nonmydriatic, autofocus, hand-held fundus camera (Volk Optical, Mentor, Ohio, USA). Medical and ocular history, family history of glaucoma, visual acuity, and intraocular pressure measurements using the ICare rebound tonometer (ICare, Helsinki, Finland) were obtained. Images were read remotely by a trained retina reader and a glaucoma specialist. RESULTS: From April 1, 2015, to February 6, 2017, 906 individuals consented and attended Visit 1. Of these, 553 participants were female (61.0%) and 550 were African-American (60.7%), with a mean age of 58.7 years. A total of 532 (58.7%) participants had diabetes, and 616 (68%) had a history of hypertension. During Visit 1, 356 (39.3%) participants were graded with a normal image. Using image data from the worse eye, 333 (36.8%) were abnormal and 155 (17.1%) were unreadable. A total of 258 (28.5%) had a suspicious nerve, 62 (6.8%) had ocular hypertension, 102 (11.3%) had diabetic retinopathy, and 68 (7.5%) had other retinal abnormalities. CONCLUSION: An integrated telemedicine screening intervention in primary care offices and Federally Qualified Health Centers detected high rate of suspicious optic nerves, ocular hypertension, and retinal pathology.

Impossibility to eliminate observer effect in the assessment of adherence in clinical trials.

PURPOSE: To utilize the Travoprost Dosing Aid (DA) in the assessment of patient medication adherence, while also determining whether or not altering the functionality of the DA in three randomized subject groups can reduce observer effect. METHODS: Forty-five subjects were randomized into three groups: two with monitored DAs and one without monitoring. One group of subjects was given a DA that both monitored drop usage and had visual and audible alarms, while the other monitored group included subjects given a DA that had no alarms but continued to monitor drop usage. The third group was given a DA that had no alarm reminders or dose usage monitoring. Subjects were informed that some monitors would not be functional, in an attempt to reduce observer effect, or the effect of being monitored on subject behavior and adherence. A six-item questionnaire was also utilized to assess how the subjects felt about their adherence and DA use. RESULTS: The overall adherence rates were found to be 78% in the fully functional group (95% confidence interval: 70-88) and 76% in the no alarms group (95% confidence interval: 65-89). No association was seen between questionnaire response and medication adherence. The patients in the DA group without alarms had a significantly higher odds ratio of medication adherence if they reported on the questionnaire that using the DA did affect how much they used their drops. CONCLUSION: Though the use of DA was expected to reveal different rates of adherence depending on the functionality of the DA between groups, patients with a nonfunctioning DA did not have a significant difference in medication adherence compared to those given a fully functional DA. This supports that an observer effect was not reduced despite these interventions, and that the subjects adhered to taking their medications as if they had a functioning DA and were being monitored.

Overcoming Barriers to Eye Care: Patient Response to a Medical Social Worker in a Glaucoma Service.

This paper investigates the patient response to a medical social worker in a glaucoma clinic. The literature suggests that medical social workers are effective in a variety of health care settings, yet the efficacy of a medical social worker in an adult ophthalmic setting has not been studied. We present the results of a retrospective chart review of 50 patients with glaucoma referred to a medical social worker between January 5, 2015 and June 31, 2015 in an outpatient clinic of an urban eye hospital. Clinical and demographic data, as well as the data from a quality of care questionnaire, were collected for each patient. Patients rated their interaction with the medical social worker as highly positive (mean = 4.75, 5-point Likert scale), and nearly 90 % of patients expressed interest in future contact with the social worker. Additionally, most patients reported that the social worker resolved the issues they were facing (61.1 %), supported them in seeing their ophthalmologist (70.6 %), and helped them to manage their glaucoma (69.7 %). Reported barriers to glaucoma care were emotional distress; cost of office visits and medications; lack of medical insurance; transportation; poor medication adherence; impairment of daily activities; follow-up adherence; and language. As vision loss from glaucoma is irreversible, it is important to detect and treat patients at early stages of the disease. Therefore, it is imperative for patients to regularly visit their eye care providers and adhere to treatment and follow-up recommendations. This study suggests that a medical social worker could play a pivotal role in helping patients with glaucoma overcome barriers to treatment and facilitate disease management.

Factors contributing to nonadherence to follow-up appointments in a resident glaucoma clinic versus primary eye care clinic.

PURPOSE: To determine the rate of adherence to follow-up appointment recommendations in a resident glaucoma clinic with no mechanism for reminders, compared to a resident cataract and primary eye care (CPEC) clinic in which telephone reminders were used, and to identify factors that contribute to adherence in each patient group. METHODS: This retrospective cohort study included subjects in the CPEC clinic who received telephone reminders and those in the glaucoma clinic who did not. Each sample was selected to have a similar proportion of follow-up recommendations for 1, 3, and 6 months. Subjects were considered adherent if they returned within a specified timeframe. RESULTS: A total of 144 subjects from the glaucoma clinic and 151 subjects from the CPEC clinic were included. There was no significant difference between follow-up adherence rates of patients who received telephone reminders and those who did not (odds ratio [OR] =1.35, 95% confidence interval [CI] 0.79-2.32, P=0.28). Patients who were on more than two ocular medications were more likely to return for follow-up (OR=3.11, 95% CI 1.53-6.35, P=0.0018). Subjects between the ages 50 and 80 years were more likely to be adherent compared to their younger and older peers (P=0.02). CONCLUSION: The follow-up adherence of patients in a CPEC clinic who received telephone reminders was similar to patients in a glaucoma clinic who did not receive any intervention to increase their adherence. Younger (⩽50 years old) and elderly (⩾80 years old) subjects, as well as patients using less than two glaucoma medications, were less likely to adhere to their follow-up appointments.

Explantation of the novel Ahmed glaucoma valve M4 implant.

PURPOSE: To report a series of cases involving Ahmed Glaucoma Valve M4 (AGV) explantation and to discuss the surgical technique to remove the drainage device. METHODS: Four cases were identified that presented with AGV M4 postoperative complications necessitating tube shunt removal. Three patients presented with conjunctival erosion and 1 patient with persistent diplopia. AGV M4 implants were removed successfully between 1.5 and 9 months after implantation. RESULTS: Successful explantation of the AGV M4 novel implant was achieved in all cases without intraoperative or postoperative complications. CONCLUSIONS: If necessary, AGV M4 explantation can be successfully performed in the early postoperative period.

The changing conceptual basis of trabeculectomy: a review of past and current surgical techniques.

The original intent of glaucoma surgery was to allow aqueous humor to exit more easily either through the sclera or into the suprachoroidal space. The former came to be called, generically, a glaucoma filtering procedure. As this surgery evolved, some explored the concept of lowering pressure without producing a hole in the sclera, with its resultant "filtering bleb." For example, Cairns hoped that cutting open the edges of Schlemm's canal would allow aqueous to leave without producing a filtering bleb; however, it became apparent that Cairns's "trabeculectomy" only worked when a filtering bleb developed. The goal of today's trabeculectomy is the creation of a longlasting transscleral fistula. In fact, trabeculectomy is a misnomer as excision of trabecular meshwork is unimportant. Frequently, the tissue excised to create a trans-scleral fistula is sclera, cornea, or both. The current trabeculectomy is really a guarded sclerokeratectomy. Newer techniques hope to increase aqueous outflow through Schlemm's canal to avoid complications associated with subconjunctival filtering blebs. Non-penetrating glaucoma surgeries (deep sclerectomy, viscocanalostomy) and ab interno trabecular surgery attempt to lower intraocular pressure with bleb-less procedures. We describe the recent evolution of glaucoma surgery, particularly the idea that intraocular pressure may be lowered satisfactorily without creating a filtering bleb.