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Biomedical subjects

A L Coleman

Publications and source records attributed to A L Coleman.

At least 19 recordsLinked to original sources
PubMed2001

Relationship between aqueous humor protein level and outflow facility in patients with uveitis.

PURPOSE: To determine whether there is a relationship between the aqueous humor protein level and outflow facility in patients with uveitis. METHODS: Aqueous humor protein levels were determined by laser flare photometry, and outflow facility was determined by Schiotz tonography. RESULTS: Thirty patients with uveitis and 10 control subjects were studied. Outflow facility was lower in patients with uveitis (0.21 +/- 0.12 microl/min x mm Hg) than in control subjects (0.33 +/- 0.05 microl/min x mm Hg, P < 0.001). Patients with uveitis and laser flare photometry results (flare) more than 20 photon units/msec (n = 21) had a lower outflow facility (0.17 +/- 0.07 microl/min x mm Hg) than patients with uveitis and flare less than 20 photon units/msec (n = 9, 0.32 +/- 0.14 microl/min x mm Hg, P = 0.004). Furthermore, no difference was identified between outflow facility in patients with active uveitis (those who had anterior chamber cells) and flare less than 20 photon units/msec and outflow in control subjects. In patients with uveitis, there was a linear correlation between flare and outflow facility (r = -0.50, P = 0.005). There was no relationship between flare measurements and either intraocular pressure or aqueous humor cell levels when scored with a clinical, semiquantitative system. CONCLUSIONS: Outflow facility is significantly reduced in patients with uveitis who have high aqueous humor protein levels. Outflow facility appears to be normal in patients with active uveitis whose flare levels are low, and therefore the association between flare and outflow facility does not appear to be an indirect reflection of elevated anterior chamber cells. It is possible that elevated aqueous humor protein levels contribute to the development of uveitic glaucoma in some individuals by decreasing aqueous humor outflow facility, although a causal relationship cannot be established on the basis of this study.

Adult↗
PubMed2001

The glaucomas.

Glaucoma is the leading cause of irreversible blindness worldwide. The World Health Organization reported in 1995 that 5.1 million persons were bilaterally blind from glaucoma. Its morbidity and prevalence make it a significant public health problem. Because it is a treatable condition, it is important that medical professionals be familiar with this disease, which in most cases is not associated with signs and symptoms that may alert the patient or the physician of its presence. Glaucoma is a progressive optic neuropathy that leads to blindness if left untreated. Risk factors include elevated intraocular pressure, advanced age, African ancestry and positive family history. Several types of glaucomas have been described: acute and chronic, secondary and primary. Primary (Chronic) Open Angle Glaucoma is the most common, with a prevalence in the USA of 1.55%. Blacks are 4 to 5 times more affected than whites. Treatment of glaucoma consists of topical or systemic intraocular pressure lowering agents, laser treatment or surgery. Primary Open Angle Glaucoma is an often-unrecognized disease due to its slow course and lack of symptoms. Because the decline in vision may be slowed but not restored by treatment, it is important that this condition be diagnosed early in its course.

Adult↗
PubMed2000

Surgical undertreatment of glaucoma in black beneficiaries of medicare.

OBJECTIVE: To identify whether there was surgical undertreatment of glaucoma in black beneficiaries of Medicare from 1991 to 1994. METHODS: We performed a retrospective cohort analysis on all argon laser trabeculoplasty or trabeculectomy surgery claims to the Health Care Financing Administration between 1991 and 1994. There were 191 287 Medicare patients who were black or white, at least 65 years of age, and resided in the United States at the time of their glaucoma surgery. Age- and sex-adjusted rates were obtained and compared with surgery rates expected based on disease prevalence. RESULTS: The age-sex-adjusted rate ratio of glaucoma surgical procedures for blacks to whites was 2.14. Assuming that treatments should be done in proportion to age-race prevalence, blacks undergo glaucoma surgery at approximately 47% below the expected rate. CONCLUSIONS: Blacks underwent argon laser trabeculoplasties and trabeculectomies at half the rate of whites from 1991 to 1994. Although in 1993 and 1994 there was a slight trend toward higher surgery rates in blacks, the magnitude of this improvement was small compared with estimated differences in the surgery rates between blacks and whites.

Black or African American↗
PubMed1999

Glaucoma.

In 2000 an estimated 66.8 million people worldwide will have glaucoma, 6.7 million of whom will be bilaterally blind from irreversible optic-nerve damage. Yet even in developed countries with public educational programmes that target glaucoma, half of the individuals with glaucoma remain undiagnosed. Patients with even mild visual impairment secondary to glaucoma may have difficulties with mobility, driving, and social interactions. Although glaucoma may be associated with increased eye pressures, its diagnosis does not rely on a specific level of eye pressure. Diagnosis of glaucoma often relies on examination of the optic disc and assessment of the visual field. The two most common types of glaucoma--primary open-angle glaucoma and primary angle-closure glaucoma--have different risk factors. Although similar medications can be used to treat these two types of glaucoma, the overall management of patients differs in important ways. Until recently, there were no randomised clinical trials that showed the effectiveness of lowering eye pressures with medications or surgery in patients with glaucoma. However, in 1998 a randomised clinical trial showed the benefit of lowering eye pressure in patients with glaucoma who had eye pressures of 24 mm Hg or less. Because glaucoma is treatable, and because the visual impairment from glaucoma is irreversible, early detection of the disease is critically important.

Blindness↗
PubMed1999

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.

Adolescent↗
PubMed1999

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.

Female↗
PubMed1999

Ahmed glaucoma valve implant for management of glaucoma in Sturge-Weber syndrome.

PURPOSE: To evaluate the safety and efficacy of the Ahmed glaucoma valve implant in patients with glaucoma as a result of Sturge-Weber syndrome. METHODS: Eleven eyes (10 patients) with glaucoma resulting from Sturge-Weber syndrome had placement of an Ahmed glaucoma valve implant from May 1993 to June 1996 at the Jules Stein Eye Institute. Success was defined by intraocular pressure at the last two consecutive visits of less than 21 mm Hg, no additional glaucoma surgery, no expulsive choroidal hemorrhage, and no retinal detachment. RESULTS: Mean intraocular pressure on the first postoperative day was 14.0 mm Hg (SD +/- 6.7). The cumulative probability of success was 79% (95% confidence interval [CI], 52% to 100%) at 24 months, 59% (95% CI, 20% to 98%) at 42 months, and 30% (95% CI, 0% to 75%) at 60 months. CONCLUSIONS: On the basis of limited follow-up, the Ahmed glaucoma valve implant appears to be a relatively useful drainage device in eyes with glaucoma resulting from Sturge-Weber syndrome.

Adolescent↗
PubMed1999

Longitudinal changes in optic disc topography of adult patients after trabeculectomy.

OBJECTIVE: To study longitudinal changes in optic disc topography after trabeculectomy in adult patients. DESIGN: Prospective case series. PARTICIPANTS: Twenty-five eyes of 25 patients undergoing trabeculectomy were enrolled. INTERVENTION: Images of the optic disc were obtained preoperatively and approximately 2 weeks, 4 months, and 8 months after surgery by use of a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph). MAIN OUTCOME MEASURES: The topographic optic disc parameters (cup volume, cup area, rim volume, rim area, cup-disc area ratio, mean cup depth, maximum depth, cup shape, and height variation contour) were measured automatically for each image with the Heidelberg Retina Tomograph Software (version 1.11). RESULTS: Approximately 2 weeks after surgery, the mean preoperative intraocular pressure (IOP) of 19.3 mmHg (SD, 6.4 mmHg) decreased to 6.0 mmHg (SD, 3.6 mmHg), cup volume and mean cup depth decreased, height variation contour increased, and the cup shape parameter became more negative. Approximately 4 months after surgery, mean IOP was 9.7 mmHg (SD, 4.2 mmHg), and the only statistically significant change from preoperative values of optic disc parameters was in the cup shape measure. Approximately 8 months after surgery, there was no statistically significant change in any of the optic disc parameters compared with preoperative values, although IOP was 10.4 mmHg (SD, 5.9 mmHg). CONCLUSIONS: Changes in the optic disc that may be present 2 weeks after a trabeculectomy do not appear to persist 4 and 8 months later in eyes with advanced glaucomatous optic nerve damage, except for cup shape, which was different from preoperative values at 4 months but not at 8 months.

Aged↗
PubMed1998

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.

Adult↗
PubMed1998

Factors associated with elevated rates of adverse outcomes after cyclodestructive procedures versus drainage device procedures.

OBJECTIVE: To identify factors associated with an increased risk of adverse outcomes after cyclodestructive or drainage device procedures. DESIGN: Retrospective, cohort analysis. PARTICIPANTS: A total of 5570 Medicare patients who were older than 65 years of age and who underwent cyclodestructive or drainage device procedures in 1994 participated. INTERVENTION: The authors identified cyclodestructive and drainage device procedures from claims to the Health Care Finance Administration (HCFA) by International Classification of Diseases (ICD-9) procedure codes, Current Procedural Terminology procedure codes, and HCFA Common Procedural Classification System codes. The authors analyzed adverse outcome rates using hierarchical logistic regression. Race, age group, gender, length of observed follow-up, state in which surgery took place, ocular procedures performed before and at the same time as the index surgery, and ocular diagnosis were included as covariates in the model. MAIN OUTCOME MEASURES: The authors defined an adverse outcome as the occurrence after the index surgery of at least one of the following: repeat cyclodestructive or drainage device procedure, retinal hole-tear repair, retinal detachment repair, surgery for endophthalmitis, vitrectomy, enucleation, evisceration, surgery for ocular hypotony, and/or extrusion or revision of drainage device. Adverse outcomes were also defined without the inclusion of repeat cyclodestructive or drainage device procedures. RESULTS: When repeat cyclodestructive or drainage device procedures were not included in the definition of an adverse outcome, eyes with a drainage device procedure were 3.8 times more likely to have an adverse outcome than eyes with a cyclodestructive procedure (odds ratio [OR], 3.8; 95% confidence interval [CI], 3.07, 4.67). Subjects with concurrent corneal transplant had increased odds of an adverse outcome compared to subjects without a concurrent corneal transplant (OR, 2.00; 95% CI, 1.27, 3.15). When the definition of an adverse outcome included repeat cyclodestructive or drainage device procedures, the odds of an adverse outcome were similar for both cyclodestructive and drainage device procedures (OR, 0.94; 95% CI, 0.79, 1.13). CONCLUSIONS: Cyclodestructive procedures need to be repeated more frequently than drainage device procedures. However, if the patient has a drainage device procedure, then that patient is more likely to have other types of adverse ophthalmic events than if he or she had a cyclodestructive procedure. Because the average follow-up of subjects in this study is 5 months (range, 0-12 months), outcomes that might take longer to manifest themselves would be excluded from this study.

Aged↗
PubMed1998

Factors associated with elevated complication rates after partial-thickness or full-thickness glaucoma surgical procedures in the United States during 1994.

OBJECTIVE: The purpose of the study was to identify factors associated with an increased risk of complications after partial-thickness or full-thickness glaucoma surgery. DESIGN: A retrospective, cohort analysis. PARTICIPANTS: A total of 24,206 Medicare patients who were older than 65 years of age and who were enrolled in Medicare in 1994 underwent partial-thickness or full-thickness glaucoma surgical procedures in 1994. INTERVENTION: The authors obtained data on all glaucoma surgery claims to the Health Care Finance Administration in 1994 and analyzed complication rates using hierarchical logistic regression, separately smoothing four sets of regression coefficients (state-level effects, systemic and ocular diagnoses, prior ocular surgeries, and concomitant ocular surgeries). MAIN OUTCOME MEASURE: Patients were classified as having complications if their records showed at least one of the following occurrences after surgery: retinal detachment repair, endophthalmitis, scleral fistula revision-repair, or cyclodestruction. RESULTS: The risk of complications was greater for full-thickness procedures than for partial-thickness procedures (odds ratio [OR] = 1.51; 95% confidence interval [CI] = 1.07, 2.12). Compared to glaucoma surgeries performed without an additional intraocular procedure, glaucoma surgery with prior phacoemulsification (OR = 0.51; 95% CI = 0.35, 0.74) was associated with lower complication rates, as was glaucoma surgery with prior argon laser trabeculoplasty (OR = 0.62; 95% CI = 0.44, 0.88). A concomitant vitrectomy (OR = 1.86, 95% CI = 1.35, 2.56) was associated with greater odds of a complication. The mean follow-up of subjects was 184 days (standard deviation, +/- 107), whereas the mean time to a complication was 49 days (standard deviation, +/- 63). CONCLUSION: The risk of an early postoperative complication after full-thickness procedures appears to be greater than that after partial-thickness procedures. Concomitant intraocular procedures performed in conjunction with glaucoma surgery, such as a vitrectomy, can substantially increase the risk of retinal detachment repair, endophthalmitis, scleral fistula revision-repair, and/or cyclodestruction.

Aged↗
PubMed1998

Annual predictions of adverse outcomes after glaucoma surgery in the United States.

PURPOSE: To predict the number of adverse outcomes or additional ocular surgeries after glaucoma surgery in each year from 1990 to 1994 with ordinary and hierarchical logistic regression models developed with 1989 Medicare data. METHODS: We obtained data on all intraocular and laser glaucoma surgery claims (for example, laser trabeculoplasty, full-thickness and partial-thickness procedures, and cycloablation) to the Health Care Finance Administration (HCFA) in 1989 and developed an ordinary (non-hierarchical) logistic regression model and two hierarchical logistic regression models. The two hierarchical models smoothed state-level effects to different degrees in an effort to improve the precision of model predictions. RESULTS: The hierarchical logistic regression models predicted the number of adverse outcomes or additional ocular surgeries, including repeat glaucoma surgery, from 1990 to 1994 significantly better than the ordinary model. None of the models predicted the downward trend in adverse outcomes in 1990 and 1992, although all three models were able to predict the increase in adverse outcomes in 1991 and the downward trend in adverse outcomes in 1993 and 1994. CONCLUSION: Although systematic changes over time in physician practice or billing patterns affected the ability of both ordinary and hierarchical regression models to predict the number of adverse outcomes in 1990 and 1992, hierarchical logistic regression provides a useful framework for analyzing adverse event rates when the model contains many covariates with imprecisely estimated coefficients. The greater accuracy of predicted adverse event rates from ophthalmic surgeries obtained with hierarchical logistic regression will be useful for future planning and budgeting purposes.

Aged↗
PubMed1997

Initial clinical experience with the Ahmed Glaucoma Valve implant in pediatric patients.

OBJECTIVE: To evaluate the Ahmed Glaucoma Valve implant, an aqueous shunting device with a unidirectional valve mechanism, in patients younger than 18 years. DESIGN: Prospective case series. SETTING: Tertiary care hospital. PATIENTS: Twenty-one consecutive patients younger than 18 years. The median age of patients was 4.8 years (range, 0.23-17.9 years) INTERVENTION: Placement of an Ahmed Glaucoma Valve implant between April 1992 and April 1994. MAIN OUTCOME MEASURE: Time after surgery without failure. Success was defined as an average intraocular pressure less than 22 mm Hg for the last 2 follow-ups in eyes with preoperative intraocular pressure greater than 22 mm Hg, or an intraocular pressure that was lowered by at least 20% from preoperative values in eyes with preoperative intraocular pressure less than 22 mm Hg, and no additional glaucoma surgeries or visually devastating complications. RESULTS: Cumulative probabilities of success at 12 and 24 months were 77.9% +/- 8.8% and 60.6% +/- 13.7%, respectively. One eye had a flat anterior chamber and suprachoroidal hemorrhage on the first postoperative day. No other eyes had flat or shallow anterior chambers that required reformation. In 3 eyes the implant extruded from underneath the conjunctiva and was removed. In 2 other eyes the average intraocular pressure for the last 2 follow-ups was greater than 22 mm Hg. In 1 eye with an intraocular pressure less than 22 mm Hg preoperatively, the intraocular pressure was not reduced by at least 20%, although the number of antiglaucoma medications was reduced. CONCLUSION: The 12-and 24-month success rates of the Ahmed Glaucoma Valve implant are similar to those of other implants when used in a pediatric population.

Adolescent↗
PubMed1997

Clinical experience with the Ahmed Glaucoma Valve implant in eyes with prior or concurrent penetrating keratoplasties.

PURPOSE: To evaluate the Ahmed Glaucoma Valve implant, an aqueous shunting device with a unidirectional valve mechanism, in eyes with concurrent or prior penetrating keratoplasties. METHODS: Thirty-one eyes of 31 consecutive patients had placement of an Ahmed Glaucoma Valve implant. Median patient age was 65.1 years (range, 17.2 to 103.4 years). The main outcome measure was time after surgery without failure. Success was defined as no additional glaucoma surgeries or devastating visual complications, no new corneal graft failure, an intraocular pressure greater than or equal to 5 mm Hg on the last two follow-up examinations, and reduction in intraocular pressure. For eyes with preoperative intraocular pressure greater than 22 mm Hg, an average intraocular pressure of less than 22 mm Hg on the last two follow-up examinations was required. For eyes with preoperative intraocular pressure of less than 22 mm Hg, an intraocular pressure lowered by at least 20% from preoperative values was required. RESULTS: Cumulative probabilities of success at 12 and 20 months (mean +/- SD) were 75.4% +/- 8.2% and 51.5% +/- 11.4%, respectively. Eleven of 31 eyes were failures. The risk of failure in eyes with prior infectious keratitis or keratouveitis was estimated to be 5.8 times greater than that associated with eyes that underwent penetrating keratoplasties for other reasons (P = .009). CONCLUSIONS: Twelve- and 20-month success rates of the implant in eyes with prior or concurrent penetrating keratoplasties were comparable to those of other drainage devices. Eyes with prior infectious keratitis or keratouveitis were at increased risk of failure.

Adolescent↗
PubMed1996

Interobserver and intraobserver variability in the detection of glaucomatous progression of the optic disc.

PURPOSE: To evaluate the potential value of obtaining follow-up stereoscopic photographs on glaucoma suspects in identifying progressive optic nerve damage. METHODS: Nineteen sets of stereoscopic optic disc photographs, reflecting one eye from each of 19 patients at two time points, were selected from the records of subjects enrolled in the Glaucoma Screening Study. By consensus, three experts judged 13 of these eyes to have progressive glaucomatous optic nerve damage. Four other ophthalmologists who were masked to the expert panel evaluation then assessed glaucomatous progression in the same eyes. They were asked to evaluate glaucomatous progression in three ways: first, by drawing the optic nerve head appearance from initial stereoscopic photographs and later comparing their own drawings to follow-up stereoscopic photographs; second, by comparing serial stereoscopic photographs directly; and third, by comparing drawings of the optic nerve head made by another examiner to the follow-up photographs. RESULTS: Neither sensitivity nor specificity was consistently better for serial stereoscopic photographs than for drawings. Individual ophthalmologist agreement rates with the expert panel's determinations of progression were 23-62% when examiners compared their own drawings to follow-up photographs, 54-71% when examiners compared serial stereoscopic photographs, and 38-85% when comparing another ophthalmologist's drawings to follow-up photographs. CONCLUSION: Baseline stereoscopic photographs of the optic nerve head did not substantially improve recognition of progressive glaucomatous optic nerve damage when compared with the use of baseline drawings of the optic nerve head made from photographs in subjects who developed visual loss in the interim.

Disease Progression↗
PubMed1996

Determination of the real size of fundus objects from fundus photographs.

PURPOSE: The purpose of this research was to study the accuracy of measurements that rely on Littmann curves to determine the real size of fundus images. METHODS: Retinal tacks of known dimensions were placed near the optic disc in one eye of each of two cynomolgus monkeys. Images of the retinal tack and optic nerve head of these two eyes were then obtained with a Zeiss Fundus camera. The dimensions of the retinal tacks and optic discs were measured directly on the film from the Zeiss fundus camera. These measurements were then corrected with Littmann's mathematical approximations. RESULTS: In the cynomolgus eye with 19.9 mm axial length, Littmann's mathematical approximations of the real sizes of the retinal tack and optic disc from measurements on the Zeiss film had median percent bias [(calculated size-real size)/real size] of -0.2% (range, -3.2% to 3.9%). In the other eye with 17.9 mm axial length, the median percent bias was 14.7% (range, 5.1% to 29.7%). CONCLUSION: The estimation of the real size of fundus images with Littmann's mathematical approximations from images on Zeiss film have < 4% bias if the eye's dimensions fall in the range over which Littmann's curves were produced.

Animals↗
PubMed1995

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.

Adult↗