Nathan M. Radcliffe

Anatomic Relationships between Disc Hemorrhage and Parapapillary Atrophy

PURPOSE Parapapillary atrophy (PPA) and disc hemorrhage (DH) are associated with glaucoma. We sought to determine whether they are anatomically related. DESIGN Retrospective study. METHODS All digital optic nerve stereophotographs obtained over a one-year period were screened for the presence of DH. Only patients with DH were included. The location of the greatest beta zone PPA width as defined by the radial distance between the scleral rim and the outer border of the beta zone was compared in each patient. The clock hour location of the DH was determined. Baseline central corneal thickness, intraocular pressure, vertical cup-to-disc ratio, and visual field indices were obtained. RESULTS Photographs from 1,559 glaucoma patients were evaluated and 46 eyes with unilateral DH were identified; 42 (91.3%) had beta zone PPA and 38 eyes had asymmetric PPA width. DH occurred more frequently in the eye with the greater PPA width (29/38 eyes [76.3%]; kappa = 0.611; P < .001). The DH fell on the point of greatest PPA width in 10 (23.9%) of 42 eyes (P < .05, Fisher exact test) and within two clock hours of the greatest PPA width in 31 (73.8%) of 42 eyes (P < .001, Chi-square test). Logistic regression analysis determined that greater PPA width (odds ratio, 17.16; 95% confidence interval, 5.34 to 55.12; P < .001) was the only ocular characteristic to predict the laterality of the DH. CONCLUSIONS DHs tend to occur in the eye with the greatest PPA width and usually are found within the region of its greatest width.

Minimally invasive glaucoma surgery: current implants and future innovations

Traditionally, invasive surgical management of glaucoma is recommended when medication and/or laser trabeculoplasty fail to control intraocular pressure (IOP). Filtering procedures, such as trabeculectomy and glaucoma drainage devices, are effective in lowering IOP, but they have significant associated adverse events and rates of failure. For these reasons, a new group of surgical procedures has emerged that seeks to decrease IOP with lower associated rates of complications. The acronym MIGS, usually described as minimally invasive glaucoma surgery, has been coined to describe this group of procedures. As new devices become available, MIGS procedures will help to fill the gap between conservative medical and laser therapy and invasive surgical treatment of glaucoma to offer patients an earlier and safer transition to surgical management of their disease. In this review, we define the characteristics of an ideal MIGS procedure and discuss implants currently in use or under investigation.

The relationship between corneal hysteresis and the magnitude of intraocular pressure reduction with topical prostaglandin therapy

Aims To evaluate corneal hysteresis (CH) and intraocular pressure (IOP) before and after IOP lowering with prostaglandin analogue (PGA) therapy in medication-naïve eyes. Methods In this retrospective study, we included records from 57 consecutive patients with open angle glaucoma who were initiated on PGA. Patients underwent ocular response analyser measurement with IOP assessment at baseline (untreated) and at follow-up (treated). Results Median follow-up time between IOP measurements was 1.4 (range 0.4–13.5) months. IOP was reduced by 3.2 mm Hg (18.8%) from 17.0 to 13.8 mm Hg (p<0.001). CH increased by 0.5 mm Hg (5.2%) from 9.7 to 10.2 mm Hg (p=0.02). Baseline CH (but not baseline central corneal thickness) was a significant predictor of the magnitude of IOP reduction, with patients in the lowest quartile of CH (mean 7.0 mm Hg) experiencing a 29.0% reduction in IOP while those in the highest CH quartile (mean 11.9 mm Hg) experienced a 7.6% reduction in IOP (p=0.006). A multivariate analysis controlling for baseline IOP demonstrated that baseline CH independently predicted the magnitude of IOP reduction with PGA therapy in both per cent (ß=3.5, p=0.01) and absolute (ß=0.6, p=0.02) terms. Conclusion Although CH is influenced by IOP, baseline CH is independently associated with the magnitude of IOP reduction with PGA therapy.

Evaluation of agreement between intraocular pressure measurements using Goldmann applanation tonometry and Goldmann correlated intraocular pressure by Reichert's ocular response analyser

PurposeTo compare agreement of intraocular pressure (IOP) measurements using Goldmann applanation tonometry (GAT) and Goldmann correlated intraocular pressure generated (IOPg) by the Reichert ocular response analyser (ORA).MethodsConsecutive patients presenting for glaucoma evaluation underwent ORA assessment followed by examination including GAT. For each ORA assessment, measurements were taken until a waveform score (WS) of 6.5 was obtained or until five measurements were obtained per eye. The relationship between GAT and IOPg and the influence of the WS upon this relationship was evaluated. A Bland–Altman plot and linear regression were used to determine agreement between GAT and IOPg.ResultsA total of 518 eyes of 260 patients were included in the final analysis. Increasing WS was found to predict a smaller difference between GAT and IOPg (β=−0.2, P⩽0.001). Selecting the highest WS among ORA assessments of each eye, WS continued to predict concordance between GAT and IOPg (β=−0.2, P=0.006). The mean IOP difference between methods was 0.1 mm Hg (±0.3), which was found to be statistically insignificant (P=0.391). This relationship between GAT and IOPg was successfully validated using a second distinct data set of 100 eyes. GAT and IOPg measurements varied by 2 mm Hg or less in 53.9% of eyes and 5 mm Hg or less in 92.3% of eyes.ConclusionIn clinical practice IOPg is strongly related to GAT. Although higher WS is indicative of greater IOPg/GAT concordance, its influence is minimal. This study does not support the use of a specific WS cutoff to determine quality of an IOPg measurement.

Eye Cancer Related Glaucoma: Current Concepts

Eye cancer-related glaucomas occur through a variety of mechanisms. They can be challenging to diagnose and are often refractory to treatment. The literature reveals the variety of ways eye cancers cause glaucoma. Mechanisms include direct invasion, infiltration, or seeding of the aqueous outflow structures as well as indirect processes, such as compressive angle closure and anterior segment neovascularization. This review describes established, evolving, and new diagnostic techniques (e.g., high-frequency ultrasound and aspiration biopsy techniques). Treatment options typically depend upon the tumor type (primary or secondary), its location, and mechanism of glaucoma. However, they include standard pharmacologic, laser, incisional, and radiotherapeutic approaches. We hope this review leads to early detection and optimum treatment of eye cancer-related glaucomas. Clearly, prompt diagnosis and management of eye cancer-related glaucoma offers an opportunity to both preserve vision and the patients life.

Corneal hysteresis and its relevance to glaucoma.

Purpose of review Glaucoma is a leading cause of irreversible blindness worldwide. It is estimated that roughly 60.5 million people had glaucoma in 2010 and that this number is increasing. Many patients continue to lose vision despite apparent disease control according to traditional risk factors. The purpose of this review is to discuss the recent findings with regard to corneal hysteresis, a variable that is thought to be associated with the risk and progression of glaucoma. Recent findings Low corneal hysteresis is associated with optic nerve and visual field damage in glaucoma and the risk of structural and functional glaucoma progression. In addition, hysteresis may enhance intraocular pressure (IOP) interpretation: low corneal hysteresis is associated with a larger magnitude of IOP reduction following various glaucoma therapies. Corneal hysteresis is dynamic and may increase in eyes after IOP-lowering interventions are implemented. Summary It is widely accepted that central corneal thickness is a predictive factor for the risk of glaucoma progression. Recent evidence shows that corneal hysteresis also provides valuable information for several aspects of glaucoma management. In fact, corneal hysteresis may be more strongly associated with glaucoma presence, risk of progression, and effectiveness of glaucoma treatments than central corneal thickness.

Measuring hemoglobin levels in the optic nerve head: comparisons with other structural and functional parameters of glaucoma.

PURPOSE We evaluated and compared the ability of a new method for measuring hemoglobin (Hb) levels at the optic nerve head (ONH) to that of visual field evaluation, scanning laser ophthalmoscopy (HRT), scanning laser polarimetry (GDx), and optical coherence tomography (OCT) for diagnosing glaucoma. METHODS Healthy eyes (n = 102) and glaucomatous eyes (n = 101) underwent reliable Oculus Spark perimetry, and imaging with the HRT, GDx, and Cirrus OCT. In addition, ONH color images were acquired with a non-mydriatic fundus camera. The Laguna ON(h)E program then was used to calculate the Hb amount in each of 24 sectors of the ONH. Sensitivities at 95% fixed specificity, diagnostic agreement, and linear correlations between parameters with the best diagnostic ability were calculated. RESULTS The glaucoma discriminant function (GDF) of the Laguna program, evaluating Hb in the vertical intermediate sectors and center/periphery Hb amount slope, yielded an 89.1% sensitivity and 95.1% specificity, which was superior or similar to the other tests. The best GDF diagnostic agreement was for the OCT-vertical cup-to-disc (C/D) ratio (kappa = 0.772) and the final phase Spark pattern SD (kappa = 0.672). Hb levels correlated strongly with the Spark mean sensitivity (first phase 0.70, final phase 0.71). Hb also correlated well with the Reinhard OW Burk discriminant function of the HRT (0.56), nerve fiber indicator of GDx (-0.64), and vertical C/D ratio of OCT (0.71). CONCLUSIONS Hb levels evaluated by color analysis of ONH photographs had high reproducibility, a high sensitivity-specificity balance, and moderate to strong agreement with other structural and functional tests.

Variation in corneal hysteresis and central corneal thickness among black, hispanic and white subjects

Purpose:  To determine whether differences in corneal hysteresis (CH) and central corneal thickness (CCT) between black, Hispanic and white subjects exist independently of one another.

Automated alternation flicker for the detection of optic disc haemorrhages

Purpose:  Optic disc haemorrhages are associated with active glaucomatous neurodegeneration and ongoing visual field loss. We sought to determine whether automated alternation flicker enhances the detection of disc haemorrhages in serial images from patients with glaucoma when compared to side‐by‐side photographic evaluation and single‐image display.

Goldmann applanation tonometry compared with corneal-compensated intraocular pressure in the evaluation of primary open-angle Glaucoma

BackgroundTo better understand the role of corneal properties and intraocular pressure (IOP) in the evaluation of primary open-angle glaucoma (POAG); and to determine the feasibility of identifying glaucomatous optic neuropathy (GON) using IOP corrected and uncorrected for corneal biomechanics.MethodsRecords from 1,875 eyes of consecutively evaluated new patients were reviewed. Eyes were excluded if central corneal thickness (CCT) or Ocular Response Analyzer (ORA) measurements were unavailable. Presence or absence of GON was determined based on morphology of the optic disc, rim and retinal nerve fiber layer at the time of clinical examination, fundus photography and Heidelberg Retinal Tomography. Goldmann-applanation tonometry (GAT) in the untreated state was recorded and Goldmann-correlated (IOPg) and corneal-compensated IOP (IOPcc) were obtained using the ORA. Glaucomatous eyes were classified as normal or high-tension (NTG, HTG) using the conventional cutoff of 21 mm Hg. One eligible eye was randomly selected from each patient for inclusion.ResultsA total of 357 normal, 155 HTG and 102 NTG eyes were included. Among NTG eyes, IOPcc was greater than GAT (19.8 and 14.4 mm Hg; p < 0.001) and the difference between IOPcc and GAT was greatest for this subgroup of patients with NTG (p ≤ 0.01). The maximum combined sensitivity and specificity for detection of GON occurred at 20.9 mm Hg for GAT (59%, 90%) and 18.4 mm Hg for IOPcc (85%, 85%) and the area under the curve was greater for IOPcc (0.93 vs. 0.78; p < 0.001).ConclusionsIOPcc may account for measurement error induced by corneal biomechanics. Compared to GAT, IOPcc may be a superior test in the evaluation of glaucoma but is unlikely to represent an effective diagnostic test.