Anne L. Coleman

Initial Clinical Experience With the Ahmed Glaucoma Valve Implant

PURPOSE We studied the Ahmed Glaucoma Valve implant, an aqueous shunting device that has a unidirectional valve mechanism designed to prevent postoperative hypotony in eyes with intractable glaucoma. METHODS In this multicenter, prospective clinical trial, we studied 60 eyes (60 patients) with increased intraocular pressure or glaucoma that had not responded to medical treatment, laser photocoagulation, or previous glaucoma surgery, in which the Ahmed Glaucoma Valve implant was placed to decrease intraocular pressure. RESULTS Success was defined as intraocular pressure less than 22 mm Hg and greater than 4 mm Hg for two months or longer, intraocular pressure that was lowered by at least 20% from preoperative values (in eyes with preoperative intraocular pressures less than 22 mm Hg), and no additional glaucoma surgery or visually devastating complications. Cumulative probability of success at 12 months was 78%. Eight (13%) of 60 eyes had intraocular pressure less than 5 mm Hg the first postoperative day. Two other eyes had shallow anterior chambers, which required anterior chamber reformation. The major complications associated with the use of the valve were serous choroidal detachments in 13 eyes (22%), blockage of the tube in six eyes (10%), malposition of the tube in four eyes (7%), a suprachoroidal hemorrhage in one eye (2%), and corneal graft rejections in three (19%) of 16 eyes with corneal grafts. CONCLUSIONS Although the 12-month success with the Ahmed Glaucoma Valve implant is similar to that reported for other drainage devices, the complications associated with overfiltration in the immediate postoperative period appear to be less frequent than with other valved drainage devices. Randomized, prospective studies to compare the Ahmed Glaucoma Valve implant with other drainage devices are needed to make clinical comparisons of the different devices.

Intermediate-term clinical experience with the Ahmed Glaucoma Valve implant

PURPOSE We studied the intermediate-term clinical experience with the Ahmed Glaucoma Valve implant (New World Medical, Inc, Rancho Cucamonga, California). METHODS In this multicenter, retrospective case series, we studied 159 eyes (144 patients) treated with the Ahmed Glaucoma Valve with a mean +/- SEM (standard error of mean) follow-up of 13.4 +/- 0.7 months (range, 4 to 44 months). The mean +/- SEM age was 60.9 +/- 1.9 years (range, 0.1 to 103 years). Surgical success was defined as intraocular pressure less than 22 mm Hg and greater than 5 mm Hg without additional glaucoma surgery and without loss of light perception. Postoperative use of antiglaucoma medications was not a criterion for success or failure. The definition of hypotony was intraocular pressure of 5 mm Hg or less in two consecutive visits. RESULTS Intraocular pressure was reduced from a mean of 32.7 +/- 0.8 mm Hg before surgery to 15.9 +/- 0.6 mm Hg (P < .0001) at the most recent follow-up after surgery. The number of antiglaucoma medications was decreased from 2.7 +/- 0.1 before surgery to 1.1 +/- 0.1 after surgery (P < .0001). The cumulative probability of success was 87% at 1 year and 75% at 2 years after surgery (Kaplan-Meier life-table analysis). Postoperatively, 24 (15%) of 159 eyes had intraocular pressure greater than or equal to 22 mm Hg. The visual acuity was improved or within one Snellen line in 131 eyes (82%). Complications occurred in 75 eyes (47%), the majority of which did not affect surgical outcome. The most common complication was obstruction of the tube, which was observed in 17 eyes (11%). Transient postoperative hypotony was found in 13 eyes (8%). CONCLUSIONS The Ahmed Glaucoma Valve implant is effective in lowering intraocular pressure, and postoperative hypotony is not commonly associated with this implant.

Risk Factors for Glaucoma Onset and Progression

In this review, we distinguish among risk factors associated with the development of open-angle glaucoma in individuals with healthy eyes, predictive determinants for the development of open-angle glaucoma in subjects with ocular hypertension, and prognostic factors for the progression of open-angle glaucoma in individuals who already have the disease. We primarily reviewed recent longitudinal population-based epidemiological studies, prospectively planned clinical trials, and cohort studies. Risk factors consistently associated with the development of open-angle glaucoma in individuals with healthy eyes include older age and an approximately 1 mm Hg increase in intraocular pressure (IOP) at baseline. Family history for open-angle glaucoma may be associated with the development of open-angle glaucoma as well. Predictive factors for the development of open-angle glaucoma in individuals with ocular hypertension may be older age, thinner central corneal thickness, higher cup-to-disk ratios of the optic disc, and higher pattern standard deviation values on the Humphrey automated perimeter at baseline. Given multi-center trials that showed similar predictive factors for the development of open-angle glaucoma in individuals with ocular hypertension, a calculator is available to clinicians for assessing the 5-year likelihood of developing open-angle glaucoma in ocular hypertensive patients with certain characteristics. Prognostic factors for the progression of open-angle glaucoma in individuals who already have the condition include older age at baseline, higher IOP at baseline, and thinner central conreal thickness. Self-report of diabetes may be associated with open-angle glaucoma progression. In conclusion, the only modifiable factor associated with open-angle glaucoma that has been consistently identified is elevated baseline IOP. Future research needs to evaluate the importance of others modifiable factors such as IOP fluctuation or nutritional factors.

Vision impairment and combined vision and hearing impairment predict cognitive and functional decline in older women.

Objectives: To determine the association between vision and hearing impairment and subsequent cognitive and functional decline in community‐residing older women.

Follow-up of the original cohort with the Ahmed glaucoma valve implant

PURPOSE To study the long-term results of the Ahmed glaucoma valve implant in patients with complicated glaucoma in whom short-term results have been reported. METHODS In this multicenter study, we analyzed the long-term outcome of a cohort of 60 eyes from 60 patients in whom the Ahmed glaucoma valve was implanted. Failure was characterized by at least one of the following: intraocular pressure greater than 21 mm Hg at both of the last two visits less than 6 mm Hg at both of the last two visits, loss of light perception, additional glaucoma surgery, devastating complications, and removal or replacement of the Ahmed glaucoma valve implant. Devastating complications included chronic hypotony, retinal detachment, malignant glaucoma, endophthalmitis, and phthisis bulbi; we also report results that add corneal complications (corneal decompensation or edema, corneal graft failure) as defining a devastating complication. RESULTS The mean follow-up time for the 60 eyes was 30.5 months (range, 2.1 to 63.5). When corneal complications were included in the definition of failure, 26 eyes (43%) were considered failures. Cumulative probabilities of success at 1, 2, 3, and 4 years were 76%, 68%, 54%, and 45%, respectively. When corneal complications were excluded from the definition of failure, 13 eyes (21.5%) were considered failures. Cumulative probabilities of success at 1, 2, 3, and 4 years were 87%, 82%, 76%, and 76%, respectively. Most of the failures after 12 months of postoperative follow-up were because of corneal complications. CONCLUSIONS The long-term performance of the Ahmed glaucoma valve implant is comparable to other drainage devices. More than 12 months after the implantation of the Ahmed glaucoma valve implant, the most frequent adverse outcome was corneal decompensation or corneal graft failure. These corneal problems may be secondary to the type of eyes that have drainage devices or to the drainage device itself. Further investigation is needed to identify the reasons that corneal problems follow drainage device implantation.

Blood Pressure, Perfusion Pressure, and Glaucoma

PURPOSE To provide a critical review of the relationships between blood pressure, ocular blood flow, and glaucoma and the potential for glaucoma treatment through modulation of ocular perfusion. DESIGN Summaries of the pertinent literature and input from glaucoma researchers and specialists with relevant experience. METHODS Review and interpretation of selected literature and the results of a 1-day group discussion involving glaucoma researchers and specialists with expertise in epidemiology, blood flow measurements, and cardiovascular physiology. RESULTS Accurate, reproducible, and clinically relevant measurements of blood flow within the optic nerve head and associated capillary beds are not fully achievable with current methodology. Autoregulation of blood flow in the retina and optic nerve head occurs over a large range of intraocular pressures and blood pressures. Regulation of choroidal blood flow is provided by a mix of neurohumoral and local mechanisms. Vascular factors may be important in a subgroup of patients with primary open-angle glaucoma, and particularly in patients with normal-tension glaucoma and evidence of vasospasm. Low ocular perfusion pressure and low blood pressure are associated with an increased risk of glaucoma in population-based studies. The physiologic nocturnal dip in blood pressure is protective against systemic end-organ damage, but its effects on glaucoma are not well elaborated or understood. Large-scale longitudinal studies would be required to evaluate the risk of glaucomatous progression in non-dippers, dippers, and extreme nocturnal blood pressure dippers. CONCLUSIONS Decreases in perfusion pressure and blood pressure have been associated with glaucoma. However, there is no evidence to support the value of increasing a patients blood pressure as therapy for glaucoma. Such recommendations are not currently warranted, since we lack crucial information about the microvascular beds in which perfusion is important in glaucoma, and the appropriate methods to evaluate their blood flow. There are also cardiovascular safety concerns associated with treatments designed to increase ocular perfusion pressure and blood flow by increasing blood pressure, especially in elderly patients. For these reasons and with present evidence it is unlikely that safe and effective glaucoma treatments based on altering optic nerve perfusion will soon be available.

Original ArticlesFollow-up of the original cohort with the Ahmed glaucoma valve implant1☆

PURPOSE To study the long-term results of the Ahmed glaucoma valve implant in patients with complicated glaucoma in whom short-term results have been reported. METHODS In this multicenter study, we analyzed the long-term outcome of a cohort of 60 eyes from 60 patients in whom the Ahmed glaucoma valve was implanted. Failure was characterized by at least one of the following: intraocular pressure greater than 21 mm Hg at both of the last two visits less than 6 mm Hg at both of the last two visits, loss of light perception, additional glaucoma surgery, devastating complications, and removal or replacement of the Ahmed glaucoma valve implant. Devastating complications included chronic hypotony, retinal detachment, malignant glaucoma, endophthalmitis, and phthisis bulbi; we also report results that add corneal complications (corneal decompensation or edema, corneal graft failure) as defining a devastating complication. RESULTS The mean follow-up time for the 60 eyes was 30.5 months (range, 2.1 to 63.5). When corneal complications were included in the definition of failure, 26 eyes (43%) were considered failures. Cumulative probabilities of success at 1, 2, 3, and 4 years were 76%, 68%, 54%, and 45%, respectively. When corneal complications were excluded from the definition of failure, 13 eyes (21.5%) were considered failures. Cumulative probabilities of success at 1, 2, 3, and 4 years were 87%, 82%, 76%, and 76%, respectively. Most of the failures after 12 months of postoperative follow-up were because of corneal complications. CONCLUSIONS The long-term performance of the Ahmed glaucoma valve implant is comparable to other drainage devices. More than 12 months after the implantation of the Ahmed glaucoma valve implant, the most frequent adverse outcome was corneal decompensation or corneal graft failure. These corneal problems may be secondary to the type of eyes that have drainage devices or to the drainage device itself. Further investigation is needed to identify the reasons that corneal problems follow drainage device implantation.

Functional status and well-being in patients with glaucoma as measured by the Medical Outcomes Study short form-36 questionnaire

PURPOSE This study aimed to determine whether patients with glaucoma have different functional status and well-being than patients without glaucoma. DESIGN Prospective case-control study. PARTICIPANTS The study population was recruited from 2 university-based glaucoma clinical practices and a university-based general ophthalmology clinic and consisted of 121 patients with open-angle glaucoma, 42 with diagnosis of glaucoma suspect, and 135 with no chronic ocular conditions except cataract. INTERVENTION Administration of Medical Outcomes Study 36-item short-form survey (SF-36) was performed. Demographic information, medical history, and responses to the SF-36 questionnaire were elicited by an interviewer. Medical record review was performed to obtain clinical examination data and to substantiate the medical and demographic data obtained by the interviewer. MAIN OUTCOME MEASURES The SF-36 scores by diagnostic group, demographic characteristics, and medical history were examined. Secondary outcome measures were SF-36 scores in patients with glaucoma by visual field impairment and glaucoma medication use. RESULTS Patients with glaucoma consistently had lower scores, control subjects had higher scores, and glaucoma suspects had scores intermediate between the two groups. After adjusting for the possible influence of all the other covariate factors, glaucoma was found to be a strong predictor of lower SF-36 scores. CONCLUSION Patients with glaucoma have lower scores, indicating less-functional status, than patients without glaucoma as tested by the SF-36 survey questionnaire.

Baerveldt-350 implant versus Ahmed valve for refractory glaucoma: a case-controlled comparison.

PurposeTo compare the efficacy of intraocular pressure (IOP) control of the Baerveldt-350 implant with tube ligature and the Ahmed valve in patients with refractory glaucoma. Patients and MethodsFour hundred seventy glaucoma drainage device procedures from July 1995 to July 2001 (6 years) were reviewed retrospectively. Thirty-two cases of Baerveldt-350 implantation performed in patients with glaucoma refractory to medical treatment and filtering procedures, without previous drainage device or cyclodestructive procedures, and with a minimum of 1-year follow-up were identified. Thirty-two cases of Ahmed valve implantation were matched case by case with 32 Baerveldt-350 cases for age, race, gender, glaucoma subtype, previous ocular history, preoperative IOP, and surgeon who performed the implantation. The two groups were compared for IOP control, visual outcome, complication rate, and surgical success rate. Surgical success rate was defined as an IOP reduction greater than or equal to 30% and final IOP more than 5 mm Hg and less than 22 mm Hg, without devastating complications. ResultsOver a follow-up period of 1 year, no statistically significant differences were detected between the Baerveldt-350 implant versus Ahmed valve for IOP control (12.1 ± 5.3 mm Hg vs. 13.6 ± 5.6 mm Hg respectively, at a power of 90% to detect a difference of 3.2 mm Hg between the two groups and P = 0.05), surgical success rate (65.6% vs. 65.6% respectively, complete and qualified combined), postoperative hypotony rate (37.5% vs. 34.4% respectively), and visual acuity changes of more than 1 line in Snellen visual acuity (43.3% vs. 29.0% respectively). ConclusionIn a case-controlled comparison, the Baerveldt-350 implant and the Ahmed valve had similar IOP control and surgical outcomes in patients with refractory glaucoma at 1-year follow-up.

Risk of Fractures Following Cataract Surgery in Medicare Beneficiaries

CONTEXT Visual impairment is a known risk factor for fractures. Little is known about the association of cataract surgery with fracture risk. OBJECTIVE To determine the association of cataract surgery with subsequent fracture risk in US Medicare beneficiaries with a diagnosis of cataract. DESIGN, SETTING, AND PARTICIPANTS Retrospective study of 1-year fracture incidence in a 5% random sample of Medicare Part B beneficiaries with cataract who received and did not receive cataract surgery from 2002 through 2009. MAIN OUTCOME MEASURES One-year incidence of hip fractures. Analyses were adjusted for age; sex; race/ethnicity; US region of residence; systemic comorbidities, including Charlson Comorbidity Index (CCI) score; ocular comorbidities; cataract severity; and presence of physically limiting conditions. Adjusted odds ratios (ORs) of hip fractures were calculated using logistic regression modeling. RESULTS There were 1,113,640 US Medicare beneficiaries 65 years and older with a diagnosis of cataract between 2002 and 2009 in the 5% random sample; of these patients, 410,809 (36.9%) received cataract surgery during the study period. There were 13,976 patients (1.3%) who sustained a hip fracture during the study period. The most common fracture-related comorbidity was osteoporosis (n = 134,335; 12.1%). The most common ocular comorbidity was glaucoma (n = 212,382; 19.1%). Compared with 1-year hip fracture incidence in patients with cataract who did not have cataract surgery, adjusted OR of hip fracture within 1 year after cataract surgery was 0.84 (95% CI, 0.81-0.87) with an absolute risk difference of 0.20%. Compared with matched subgroups of patients who did not receive cataract surgery, patient subgroups that experienced lower odds of hip fracture after cataract surgery included patients with severe cataract, patients most likely to receive cataract surgery based on propensity score, patients 75 years and older, and patients with a CCI score of 3 or greater. CONCLUSION In a cohort of US Medicare beneficiaries aged 65 years and older with a diagnosis of cataract, patients who had cataract surgery had lower odds of hip fracture within 1 year after surgery compared with patients who had not undergone cataract surgery.