Discordance between structure and function in glaucoma: Possible anatomical explanations

Predicting 60-4 visual field tests using 3D facial reconstruction

BACKGROUND

Despite, the potential clinical utility of 60-4 visual fields, they are not frequently used in clinical practice partly, due to the purported impact of facial contour on field defects. The purpose of this study was to design and test an artificial intelligence-driven platform to predict facial structure-dependent visual field defects on 60-4 visual field tests.

METHODS

Subjects with no ocular pathology were included. Participants were subject to optical coherence tomography, 60-4 Swedish interactive thresholding algorithm visual field tests and photography. The predicted visual field was compared with observed 60-4 visual field results in subjects. Average and point-specific sensitivity, specificity, precision, negative predictive value, accuracy, and F1-scores were primary outcome measures.

RESULTS

30 healthy were enrolled. Three-dimensional facial reconstruction using a convolution neural network (CNN) was able to predict facial contour-dependent 60-4 visual field defects in 30 subjects without ocular pathology. Overall model accuracy was 97%±3% and 96%±3% and the F1-score, dependent on precision and sensitivity, was 58%±19% and 55%±15% for the right eye and left eye, respectively. Spatial-dependent model performance was observed with increased sensitivity and precision within the far inferior nasal field reflected by an average F1-score of 76%±20% and 70%±29% for the right eye and left eye, respectively.

CONCLUSIONS

This pilot study reports the development of a CNN-enhanced platform capable of predicting 60-4 visual field defects in healthy controls based on facial contour. Further study with this platform may enhance understanding of the influence of facial contour on 60-4 visual field testing.

Phenotypic Description of the Spanish Multicentre Genetic Glaucoma Group Cohort

INTRODUCTION

The aim of the study was to make a phenotypic description of the Spanish multicentre glaucoma group cohort of patients.

DESIGN

Retrospective, observational, multicentre, cohort study.

MATERIAL AND METHODS

The clinical charts of 152 patients with hereditary glaucoma from18 Spanish eye centres were reviewed in order to make an epidemiologic description of the type of glaucoma and associated factors. True hereditary cases were compared with familiar cases according to the Gong et al. criteria.

RESULTS

61% were true hereditary cases and 39% familiar cases. Ocular comorbidity, optic disc damage, and visual field mean defect were significantly more severe in hereditary patients, who required significantly more first-line hypotensive drugs and surgical interventions to control intraocular pressure than familiar patients.

CONCLUSIONS

The strength of the hereditary component of glaucoma seems to worsen the clinical course, causing more structural and functional damage and requiring more intense glaucoma treatment. The family history of glaucoma should be carefully investigated and taken into consideration when making treatment decisions or intensifying previous treatment.

Novice Reviewers Retain High Sensitivity and Specificity of Posterior Segment Disease Identification with iWellnessExam™

Introduction. Four novices to Spectral Domain Optical Coherence Tomography (SD-OCT) image review were provided a brief lecture on the interpretation of iVue iWellnessExam™ findings (available on iVue® SD-OCT, Optovue, Inc., Fremont, CA). For a cohort of 126 (Confirmed) Normal, 101 (Confirmed) Disease subjects, iWellnessExam™ OD, OS, and OU reports were provided. Each novice independently reviewed and sorted the subjects into one of four categories: normal, retinal disease, optic nerve (ON) disease, and retinal + ON disease. Their accuracy is compared between the novices and with an expert reviewer. Results. Posterior segment disease was properly detected by novices with sensitivities of 90.6%, any disease; 84.3%, retinal disease; 88.0%, ON disease; expert sensitivity: 96.0%, 95.5%, and 90.0%, respectively; specificity: 84.3%, novices; 99.2%, expert. Novice accuracy correlates best with clinical exposure and amount of time spent reviewing each image set. The novices' negative predictive value was 92.0% (i.e., very few false negatives). Conclusions. Novices can be trained to screen for posterior segment disease efficiently and effectively using iWellnessExam™ data, with high sensitivity, while maintaining high specificity. Novice reviewer accuracy covaries with both clinical exposure and time spent per image set. These findings support exploration of training nonophthalmic technicians in a primary medical care setting.

Structure-Function Relationship between Frequency-Doubling Technology Perimetry and Optical Coherence Tomography in Glaucoma

Purpose: To assess the relationship between the retinal nerve fibre layer (RNFL) thickness and the frequency-doubling technology perimetry (FDT) outcome. Methods: Sixty-two healthy individuals and 72 glaucoma patients were prospectively selected. All participants underwent a reliable FDT and optical coherence tomography (OCT). Pearson correlations were calculated between the unlogged threshold values of FDT and RNFL thicknesses measured by OCT. Results: Mild to moderate correlations were found between a few points from FDT and RNFL thicknesses in the vertical axis. The nasal superior area of FDT and the RNFL thickness at the 7-o'clock position had the strongest correlation (0.434, p < 0.001). Conclusions: The poor agreement between FDT and OCT parameters suggests that both instruments assess different characteristics of glaucomatous optic neuropathy. The map obtained validates previously reported clinical findings and contributes to a better understanding of the structure-function relationship in glaucoma. © 2014 S. Karger AG, Basel.

Sensitivity and specificity of the iVue iWellnessExam™ in detecting retinal and optic nerve disorders

BACKGROUND

The purpose of this study was to assess the specificity and sensitivity of the iWellnessExam™ screening protocol available on iVue^® spectral domain optical coherence tomography (SD-OCT), in a cohort of confirmed normal subjects and subjects with confirmed disease.

METHODS

In total, 126 of 132 confirmed normal subjects and 101 of 107 subjects with confirmed disease were included for analysis. Of the patients with confirmed disease, 67 had retinal disease, 50 had optic nerve disease, and 16 had both retinal and optic nerve pathology. All subjects were screened on the iWellnessExam protocol. Screen shots of the OD, OS, and OU comparison data were obtained and deidentified for reviewer analysis. Based on these data alone, each subject was sorted by a well trained eye care clinician into one of four categories (1, normal; 2, retinal disease; 3, optic nerve disease; 4, retinal and optic nerve disease).

RESULTS

Of the confirmed normal subjects, 125 of 126 were correctly identified as normal (specificity 99%). Retinal and/or optic nerve disease was correctly detected in 97 of 101 patients with confirmed disease (category 2, 3, 4), retinal pathology was correctly detected in 64 of 67 patients with retinal disease (category 2, 4), and optic nerve pathology was properly detected in 45 of 50 patients with optic nerve disease (category 3, 4), with a sensitivity of 96%, 95.5%, and 90%, respectively.

CONCLUSION

The iWellnessExam offers the health care provider an excellent method for identifying eyes at risk using very reliable technology. High specificity and sensitivity was obtained when reviewed by a well trained eye care clinician. It would be valuable to repeat the study with a novice and/or student clinician reviewing the same data set to ascertain interobserver variability, as well as the impact of clinical experience on accurate referral, based on the screening data.

Psychophysical and electrophysiological testing in ocular hypertension

PURPOSE

The purpose of this study was to compare psychophysical and electrophysiological testings in early optic nerve dysfunction in a group of clinically asymptomatic subjects with suspect ocular hypertension (OHT).

METHODS

Forty eyes of 40 patients with suspect OHT and asymmetrical horizontal cup/disc ratio (0.2/0.4), 22 eyes of 22 patients with open-angle glaucoma (OAG), and 40 eyes of 40 healthy controls were evaluated by using frequency-doubling technology perimetry (FDT), contrast sensitivity (CS), pattern electroretinography (PERG), and pattern visual-evoked potentials (VEP). The VEP were elicited by checkerboard stimuli with large (VEP 120), medium (VEP 45), and small (VEP 15) checks; then the values of the amplitude (A) and latency (L) of P100 peaks were studied. Receiver operator characteristic (ROC) curves were calculated to determine the sensitivity, specificity, and optimal cutoff points of abnormal values. A logistic regression analysis was performed to determine which tests were providing the most useful information. In addition, Kruskal-Wallis test was performed to test the differences between the control group and the OHT group.

RESULTS

VEP P100 peak latency (VEP L15 and VEP L45) and amplitude (VEP A120), PERG N95 peak amplitude, CS at medium spatial frequencies (CS 4SF), and FDT pattern standard deviation (PSD) yielded the greatest sensitivity (85.0 to 60.0%) and specificity (80.0 to 60.0%) ratio, displaying the largest ROC curve areas; whereas PERG N95 peak latency ROC curve had the smallest areas. Kruskal-Wallis test showed that most diagnostic tests were able to differentiate the OHT group from the control group. Stepwise logistic regression analysis identified VEP L15 (p < 0.001), CS 4SF (p = 0.023), FDT PSD (p = 0.032), and VEP A120 (p = 0.072) as tests that could be useful to distinguish controls from OHT.

CONCLUSIONS

Our data confirm that psychophysical and electrophysiological tests are useful for early detection of patients at risk of developing OAG.