Trabeculectomy training in England: are we safe at training? Two year surgical outcomes.

OBJECTIVES: To define the safety profile of trainee trabeculectomy surgery in the United Kingdom. Surgical exposure for trainees in England is limited due to service requirements, the European working time directive constraints and increasing sub-specialisation of glaucoma surgery. Limited knowledge exists on the outcomes of supervised glaucoma surgery. The aim is to determine the safety of supervised trabeculectomy surgery performed by trainee ophthalmologists. METHODS: Retrospective case note review of all patients that had trabeculectomy surgery with MMC by consultant and trainee surgeons across multiple UK centres. All eyes have 2-year follow up. Success was determined using WGA guidelines. Two-tailed p values were obtained using Fisher's exact test to ascertain statistical significance between groups. MAIN OUTCOME MEASURES: intraocular pressure, visual acuity, success and failure rates. RESULTS: 324 eyes were reviewed. 211 (66.4%) cases were performed by glaucoma consultants, 107(33.6%) by trainee ophthalmologists. The majority of eyes in each group were undergoing surgery for POAG. Post-operative IOP control showed no significant difference between consultant and trainee groups at year 1 and year 2. Success rates showed no significant difference between consultant and trainee cases. Failure rates at year 1 showed a significant difference between the two groups. No significant difference was seen at year 2. The trainee group had significantly more complications, when compared with the consultant group. Snellen visual acuity loss was not statistically significant between the two groups at the 2 year time point. CONCLUSIONS: The outcomes of supervised trainee trabeculectomy compare favourably with consultant cases after 2 year follow up. Trainee cases had higher complication rates than consultant cases. Bleb leaks are a common complication of trainee cases, where closer supervision may be required. There is potential for surgical simulation to help increase the success of such cases. These findings may encourage trainee participation in glaucoma surgery.

Patterns of adherence behaviour for patients with glaucoma.

AIMS AND PURPOSE: Adherence to long-term treatment regimens for primary open-angle glaucoma holds a challenge for both clinicians and patients. The study aims were to (i) establish the magnitude of travoprost non-adherence using an Electronic Adherence Monitor (EAM), (ii) compare electronic with patient self-reported adherence, and (iii) explore the application of a previously reported method of graphically presenting adherence data to a larger cohort over a longer monitoring period. METHODS: A cohort study of patients using travoprost for glaucoma or ocular hypertension was conducted. All participants used an EAM and adherence data were collected prospectively for 2 months. Self-reported adherence was obtained using the Morisky Medication Adherence Scale (MMAS); patients also reported frequency of missed doses. Potential predictors of adherence were collected via a structured interview. EAM-recorded interdose intervals were plotted graphically. RESULTS: Of 100 patients invited to participate, 98 consented and EAM data were collected successfully from 88 participants. The median EAM adherence score for the cohort was 88.9% (interquartile range: 71.2, 92.2). When dichotomised (≥80%: adherent; <80%: non-adherent), EAM identified 36.7% as non-adherent and MMAS 12.2%. EAM data were used to classify five types of adherence behaviour including a category representing levels of ≥97% maintained by 21% of participants. CONCLUSION: EAM revealed good adherence to glaucoma monotherapy but poor agreement with patient self-reported adherence. An adherence category of persistent and exceptionally high adherence to travoprost over a 2-month period was identified.

Refractive error, axial length and anterior chamber depth of the eye in British adults: the EPIC-Norfolk Eye Study.

PURPOSE: To describe the distribution, and demographic and socioeconomic correlates of refractive error and related ocular biometry in an older British population. METHODS: Refractive error was measured using an auto-refractor without cycloplegia. Pseudophakic individuals and those who had undergone refractive surgery were excluded from analysis. Axial length and anterior chamber depth were measured using partial coherence laser interferometry. Occupation category and highest educational achievement were recorded. RESULTS: Biometric data were available for 2519 people (1090 men, 1429 women; 93.2% of all participants) aged 48 to 88 years. Refractive data were available for both eyes in 2210 bilaterally phakic participants. Among phakic individuals, axial length of the eye was strongly inversely correlated with refractive error in both men and women (p<0.001). Axial length of the eye was strongly, independently related to height, weight and social class, but most strongly related to educational achievement. In contrast, anterior chamber depth varied with age and sex, but not with socioeconomic status. There was a significant inverse association between anterior chamber depth and refraction in women (p<0.001) but not in men (p=0.495). CONCLUSION: Refractive error in this predominantly white older UK population was associated with axial biometry and sociodemographic characteristics. Educational status was the strongest determinant of axial length.

Barriers to adherence with glaucoma medications: a qualitative research study.

PURPOSE: Glaucoma is initially asymptomatic, but untreated can result in progressive visual field loss and eventual blindness. With adequate therapy progression can be halted, but poor adherence with medical therapy is a significant issue requiring further research. The aim of the present study was to gain a better understanding of the obstacles to, and the motivations for, adherence with glaucoma medication and explore potential methods to improve adherence. METHODS: Participants had moderate/severe glaucoma diagnosed for >1 year, had seen >or=2 NHS ophthalmologists, and were prescribed >or=2 topical medications. Qualitative methodology was utilized to investigate aspects of adherence. Recruited patients either attended a focus group or had a home-based semi-structured interview. The transcripts were member-checked and the resulting data were analysed using 'Framework' analysis. The analysis was verified by a co-investigator and NVIVO Software was used to check data reliability. RESULTS: Multiple obstacles to adherence were identified, including poor education, lack of motivation, forgetfulness, drop application, and other practical issues, together with specific individual and age differences. Motivation for adherence was determined by fear of blindness and a faith in drop efficacy. CONCLUSIONS: Specific obstacles to adherence with anti-glaucomatous therapy should be identified as early as possible after diagnosis. A tailored approach to patient care with initial education about the consequences of non-adherence and longer-term feedback about drop efficacy may improve patients' motivations for adherence. Future research should focus on investigating methods by which initial education about glaucoma and its management should best be delivered to patients.

The effect of travoprost on daytime intraocular pressure in normal tension glaucoma: a randomised controlled trial.

BACKGROUND/AIMS: To determine the medium-term effect of travoprost on the daytime intraocular pressure (IOP) of patients with normal tension glaucoma (NTG) METHODS: Newly diagnosed NTG patients underwent baseline, daytime, hourly IOP phasing. Patients were randomised to either treatment or no treatment (control). Treatment comprised once daily topical travoprost 0.004%. After 6 months, the participants underwent their second IOP phasing. RESULTS: Data from 88 participants were analysed-54 were randomised to treatment and 34 to the control group. The mean duration of treatment was 6 months. The average, maximum and minimum diurnal IOPs for treated patients were statistically significantly lower than for control patients at follow-up (p<0.001). When compared with baseline IOP, the travoprost treated group demonstrated a decrease of 16.1%, 13.5% and 16.7% in the average IOP, maximum IOP, and minimum IOP respectively. Of those treated, about one-third achieved a decrease in average IOP of at least 20%; only about one-tenth achieved a reduction of at least 30%. CONCLUSION: Travoprost monotherapy had a sustained hypotensive effect in NTG and achieved a reasonable or good response (>20% reduction in average IOP) in 32.9% of treated eyes. However, in the majority of eyes with NTG, travoprost monotherapy appeared unable to produce the desirable 30% reduction in average IOP.

Corticosteroid-induced glaucoma: a review of the literature.

The intraocular pressure rise that can complicate the use of topical or systemic corticosteroid has been recognised for 50 years. More recently, following isolation of the myocilin gene (previously known as the trabecular meshwork inducible glucocorticoid response or TIGR gene), there has been renewed interest in this steroid-responsive phenomenon. Furthermore, the currently fashionable use of injectable intraocular steroids in the management of clinically significant subretinal fluid and macular oedema has resulted in an increased incidence. Animal studies, cell biology, molecular biology, and an improved knowledge of genetics have provided a better understanding of the mechanisms behind the response. The purpose of this review is to describe the risk factors for developing corticosteroid-induced glaucoma, to discuss the underlying mechanisms and genetics of the condition and to present management options.

Comparison of pulsatile ocular blood flow in Indians and Europeans.

PURPOSE: To compare pulsatile ocular blood flow (POBF) in Europeans and Indians and provide reference values for a group of healthy Indians. PATIENTS AND METHODS: Measurement with the POBF Tonograph was performed on healthy Indian subjects in India (n=252). A further 80 subjects (40 of Indian descent and 40 Europeans) underwent measurements in Cambridge, England. The instrument used for measurement was the same for both the studies. RESULTS: The mean POBF in the Indians in India was found to be 1176 microl/min. The mean POBF value in the Europeans was found to be 1033 microl/min and that for Indians in England was 1061 microl/min. The difference between the POBF within groups was significant (one-way ANOVA P<0.05) with the POBF of Indians in India being higher than Europeans and Indians in the UK. The difference between the Europeans and Indians in the UK did not reach statistical significance. CONCLUSIONS: POBF values in Indians living in India were found to be considerably higher than the previously published normal value of 650 microl/min in European studies and other studies for other racial groups. The reason for this apparent difference may be instrument-related rather than genetic because such a large difference was not observed when a comparison was performed in the UK. In addition, the results for both groups in our comparative study were still considerably higher than reported in previous studies. The POBF of Indians in India is slightly higher than the POBF of people of Indian ethnic origin in England.

Long term effect of latanoprost on intraocular pressure in normal tension glaucoma.

AIM: To determine the long term effect of latanoprost on the intraocular pressure (IOP) of patients with normal tension glaucoma (NTG). METHODS: Newly diagnosed patients with NTG were recruited into the study and had their baseline IOPs measured hourly between 8 am and 5 pm using a handheld electronic Tonopen. Patients with fixation threatening field defects were placed immediately into the treatment group while those with non-fixation threatening field defects were randomised into either the treatment group or the control group (no treatment). Treatment consisted of once daily topical latanoprost 0.005%. After a minimum period of 6 months, the patients underwent a second period of IOP phasing. RESULTS: 76 newly diagnosed patients with NTG were recruited-26 had fixation threatening disease, 25 were randomised to treatment, and 25 randomised to the control group. The average duration of treatment was 11 months. The average and maximum diurnal IOP for the patients randomised to treatment were statistically significantly lower than for the control patients at follow up (p<0.05). The treated group as a whole demonstrated a 17% decrease in the average diurnal IOP and a 19% decrease in the maximum diurnal IOP when compared to baseline IOP. 41% of those treated achieved a decrease of at least 20%, but only 10% of patients achieved a decrease of at least 30%. CONCLUSION: Latanoprost had a sustained hypotensive effect in eyes with NTG and 41% of treated patients achieved a reasonable response. However, in the majority of eyes with NTG, latanoprost monotherapy may be insufficient in producing a desirable 30% reduction in IOP.

Effect of corneal parameters on measurements using the pulsatile ocular blood flow tonograph and Goldmann applanation tonometer.

AIMS: To investigate the effect of central corneal thickness and corneal curvature on intraocular pressure measurements using the pulsatile ocular blood flow tonograph and the Goldmann applanation tonometer, and to assess the agreement between the pulsatile ocular blood flow tonograph and the Goldmann applanation tonometer in intraocular pressure measurement. METHODS: 479 subjects underwent intraocular pressure measurements with the Goldmann applanation tonometer and the pulsatile ocular blood flow tonograph. Of these, 334 patients underwent additional measurement of central corneal thickness with an ultrasonic pachymeter and corneal curvature measurement with a keratometer. RESULTS: The intraocular pressure measurements obtained with both the Goldmann applanation tonometer and the pulsatile ocular blood flow tonograph varied with central corneal thickness and mean keratometric reading. Intraocular pressure measured using the Goldmann applanation tonometer increased by 0.027 mm Hg per micro m increase in central corneal thickness. Intraocular pressure measured using the pulsatile ocular blood flow tonograph increased by 0.048 mm Hg per micro m increase in central corneal thickness. For an increase of 1 mm of mean corneal curvature there was rise in intraocular pressure of 1.14 mm Hg measured by the Goldmann applanation tonometer and of 2.6 mm Hg measured by the pulsatile ocular blood flow tonograph. When compared to the Goldmann applanation tonometer, the pulsatile ocular blood flow tonograph underestimated at low intraocular pressure and overestimated at higher intraocular pressure. CONCLUSION: Central corneal thickness and corneal curvature affected measurements obtained with the pulsatile ocular blood flow tonograph more than they affected measurements obtained with the Goldmann applanation tonometer.

Repeatability and reproducibility of the BVI ultrasonic Pachymeter.

PURPOSE: To evaluate the interobserver and intraobserver reliability of a commercially available, portable, ultrasonic pachymeter. METHODS: For the interobserver variability study, 42 healthy subjects underwent repeated ultrasonic pachymetry under topical anaesthesia performed by two observers. For the intraobserver study, another 30 further healthy subjects underwent repeated pachymetry by one of the observers. Agreement was analysed by means of Bland-Altman plots and by determination of the intraclass correlation coefficient. RESULTS: For the interobserver variability study, the mean measurement difference between observers was 0.7 microm (95% CI -0.8-2.2 microm) and the intraclass correlation coefficient was 0.9958 (95% CI 0.9922-0.9977). The Bland-Altman plot showed narrow limits of agreement with respect to central corneal thickness (CCT). For the intraobserver variability study, the mean difference between the repeated measurements was 0.9 microm (95% CI -3.1-1.3 microm). The intraclass correlation coefficient was 0.9934 (95% CI 0.9863-0.9969). A Bland-Altman plot again showed narrow limits of agreement with respect to CCT. The mean CCT for 72 subjects was 538 microm (95% CI 528-545 microm). CONCLUSIONS: Measurements of CCT using the BVI Pocket Pachymeter were repeatable and had excellent interobserver reliability. Measurement variation amounted to less than 0.2% assuming a mean CCT of 538 microm.

A two centre study of the dose-response relation for transscleral diode laser cyclophotocoagulation in refractory glaucoma.

BACKGROUND/AIMS: Transscleral diode laser cyclophotocoagulation ("cyclodiode") is widely used to treat refractory glaucoma. The main aims of this study were to investigate the dose-response relation of cyclodiode and to evaluate possible predictive factors that would help establish optimum treatment parameters. METHODS: A retrospective analysis of the case notes of 263 eyes of 238 consecutive patients who underwent transscleral diode laser cyclophotocoagulation at two centres was undertaken. RESULTS: Mean intraocular pressure (IOP) decreased significantly from 40.7 mm Hg (SD 13.7) before cyclodiode therapy to 17.7 mm Hg (SD 10.9) post-treatment, a reduction of 52.6% (p = 0.0001). Following cyclodiode, 89% of patients achieved an IOP of less than 22 mm Hg or a greater than 30% drop in IOP. Hypotony occurred in 9.5% of patients, 76% of whom had neovascular glaucoma. A linear dose relation response was found for the 122 eyes with neovascular glaucoma (p = 0.001) but not for the group as a whole. Treatment failure was associated with male sex (multivariate regression analysis, p = 0.008) and low mean energy per treatment session (univariate analysis alone, p = 0.016). High pretreatment IOP (p = 0.031) and high mean energy per treatment episode (p = 0.001) appeared to be associated with the occurrence of hypotony, although multivariate analysis did not support this finding. CONCLUSION: Cyclodiode therapy is highly effective but there is a significant risk of hypotony, which may be reduced by applying lower energy in cases of very high pretreatment IOP and in neovascular glaucoma. The dose-response association remains unpredictable, although a linear relation was found for neovascular glaucoma.

Agreement among clinicians in the recognition of patterns of optic disk damage in glaucoma.

PURPOSE: To determine the interobserver and intraobserver agreement in the recognition of different patterns of glaucomatous optic disk damage and evaluate if these patterns changed over time in patients followed for a number of years. METHODS: Patients with early to moderate glaucoma (n = 105) were consecutively enrolled to participate in a prospective observational study. In the first part of the present study, optic disk photographs obtained closest to patient's entry date in the prospective study were classified in a masked fashion by three observers according to the pattern of optic disk damage into one of the following: (1) focal, (2) myopic, (3) senile sclerotic, (4) concentric cup enlargement, (5) normal appearance, or (6) miscellaneous (those disks that did not qualify for any of the other groups). The observers were also asked to assign a confidence score for each classification, ranging from 1 (low confidence) to 5 (highest confidence). The three observers reclassified the photographs after a minimal period of 2 months, in order to assess intraobserver agreement. In a second part of the study, one observer reviewed, in a masked fashion, all the optic disk photographs that had been taken during the routine follow-up of the 105 patients in order to evaluate whether the classification of disk pattern changed over time. RESULTS: Intraobserver agreement yielded kappa values (95% confidence interval [CI]) from 0.51 (CI, 0.40 to 0.62) to 0.85 (CI, 0.77 to 0.93) depending on the observer. Interobserver agreement kappa values between all three observers was 0.40 (CI, 0.35 to 0.46), but it improved if photographs classified with moderate or higher degrees of confidence were included (0.52 [CI, 0.44 to 0.60]). During a mean follow-up period of 8.2 +/- 4.8 years, 41.6% of the eyes were always classified into the same group and 23.6% of the eyes were classified at least once into two or more of the four patterns of damage (groups 1 to 4). CONCLUSIONS: Intraobserver agreement on the pattern of optic disk damage was generally very good, with some variation among the observers. Interobserver agreement was reasonable and increased proportionally with the confidence in the classification. During long-term follow-up, the pattern of optic disk damage usually did not change. This type of classification can probably be used accurately in clinical practice.

Survival analysis for success of Molteno tube implants.

AIM: To apply survival analysis in assessing the long term outcome of Molteno tube implantation and to identify risk factors for failure. METHODS: A retrospective, 10 year, consecutive case series study of 119 eyes that underwent implantation of a Molteno tube. The main outcome measures considered were intraocular pressure (IOP), visual acuity, and complications. RESULTS: A 30% or greater reduction in IOP was achieved in 68.9% of cases. However, the overall, "complete success" rate (IOP <22 mm Hg with no medications) after a mean (SD) follow up period of 43 (33) months (range 6-120) was only 33.6% despite a fall in mean (SD) IOP from 38.2 (8.2) mm Hg to 20.1 (11.0) mm Hg. The "qualified success" rate (IOP <22 mm Hg with or without medications) was 60.5%. Failure was most common in the first postoperative year but could occur after several years, the survival curve having an exponential shape. The only statistically significant risk factor for failure identified was pseudophakia, although eyes with neovascular glaucoma tended to fare poorly. Postoperative IOP tended to be lower after double plate than after single plate implantation. There was no significant difference in outcome based on age, sex, race, previous penetrating keratoplasty, or previous conjunctival surgery. CONCLUSIONS: In eyes at high risk of trabeculectomy failure, implantation of an aqueous shunt device should be considered. Pseudophakia should be considered an additional risk factor for failure. Early failure appeared relatively more common but long term follow up of all cases is recommended to ensure adequate management of late failures.

Cyclodiode laser therapy for painful, blind glaucomatous eyes.

AIMS: To determine the ability of cyclodiode laser treatment to relieve discomfort in painful blind glaucomatous eyes. METHODS: 30 eyes underwent cyclodiode to reduce intraocular pressure (IOP) and relieve pain. Patients graded their pre-cyclodiode and post-cyclodiode pain. RESULTS: After a minimum follow up of 6 months, a single cyclodiode treatment lowered mean IOP from 51 mm Hg (95% CI plus or minus 3.7 mm Hg) to 26 mm Hg (95% CI plus or minus 5.8 mm Hg) providing pain relief in 73.3% (22/30). After retreatment of six eyes, mean IOP was reduced to 22 (95% CI plus or minus 5.3) mm Hg and pain relief was obtained in 96.7% (29/30). For eyes achieving pain relief after one treatment, IOP was reduced by >30% in 81.0% (17/21). For eyes not achieving pain relief after one treatment, IOP was reduced by >30% in only 22.2% (2/9) (p=0.0042, Fisher's exact test). CONCLUSION: Cyclodiode was highly successful in providing pain relief in painful blind hypertensive glaucomatous eyes. The best predictor of successful pain relief was IOP reduction of > 30% from baseline.

Local anaesthetic techniques and pulsatile ocular blood flow.

AIM: To compare pulsatile ocular blood flow (POBF) and intraocular pressure (IOP) between eyes of patients receiving either peribulbar (with and without balloon compression) or subconjunctival local anaesthesia (LA). METHODS: 30 eyes of 30 patients undergoing cataract surgery by phacoemulsification were investigated in a study of parallel group design. Ten patients had peribulbar LA and 10 minutes compression with a Honan's balloon (group A). A further 10 patients who received peribulbar LA alone (group B) acted as controls for the effects of balloon compression. Ten other patients were given subconjunctival LA (group C). POBF and IOP were measured using a modified Langham pneumatonometer. Three measurements were made in each eye, the first recording immediately before LA, the second 1 minute after, and the third 10 minutes after LA. RESULTS: No significant change in POBF or IOP was recorded in eyes receiving subconjunctival LA. In the peribulbar groups (A and B), there was a drop in median POBF of 252 and 138 microl/min respectively 1 minute after LA, which was statistically significant in both groups (p<0. 01). By 10 minutes, POBF tended to return to baseline levels, but remained significantly reduced in group B (p<0.05). In addition, there was a significant (p<0.05) reduction in IOP (mean drop of 4.82 mm Hg) in group A following peribulbar LA with balloon compression. CONCLUSIONS: POBF was significantly reduced after peribulbar LA but was unchanged after subconjunctival LA. Balloon compression reduced IOP and improved POBF following peribulbar LA. The findings may have clinical implications in patients with compromised ocular circulation or significant glaucomatous optic neuropathy.

Optic disk appearances in primary open-angle glaucoma.

Primary open-angle glaucoma almost certainly develops in a multifactorial manner, with interplay between numerous risk factors affecting the disease. These risk factors, in addition to intraocular pressure, include a number of cardiovascular factors. Some of these factors may determine the appearance of the damaged glaucomatous optic nerve head. Patients with four specific optic disk appearances have been investigated, and differences have been identified in their demographic characteristics, prevalence of certain risk factors, the pattern of visual field damage, and circulatory abnormalities in their retrobulbar vessels. The findings provide evidence of the existence of subgroups of primary open-angle glaucoma with correlations between risk factor and type of optic disk. A reliable method by which the different disk appearances could be distinguished in an objective manner would be clinically valuable, and the scanning laser ophthalmoscope has shown potential promise to achieve this. The results of studies relating to various glaucomatous optic disk appearances are presented and discussed.