Discrimination Between Healthy Eyes and Those With Mild Glaucoma Damage Using Hemoglobin Measurements of the Optic Nerve Head

Frequency of the vertical cup-to-disc ratio to normal optical disc size

The relationship between the optic disc area and the vertical cup/disc ratio is presented by means of a graphic nomogram after studying a total of 365,356 normal optic nerves. For this purpose, the Laguna ONhE application was used, which analyses the distribution of hemoglobin based on the colorimetric analysis of fundus color images. The 1%, 5%, 50% and 95% percentiles are given for disc areas between 1 mm2 and 4 mm2. The highest cup-to-disc ratios (1%-5% percentiles) were close to 0.7 for large discs, while for more common sizes (1.9-2.0 mm2) they were close to 0.6 and for small ones to 0.5. Data allowed the Laguna ONhE Globin Discriminant Function (GDF) index to be corrected, in such a way that it could, then, be verified in 544 normal eyes that it was less dependent on the vertical cup/disc ratio, whereas in 436 confirmed and suspected glaucoma an intimate relationship was reported.

Estimation of normal and glaucomatous optic nerve morphology from perfusion

OBJECTIVE

To estimate the optic nerve head morphology from its haemoglobin (Hb) distribution.

METHODS AND ANALYSIS

The optic disc of 189 normal eyes and 292 with confirmed and suspected glaucoma were analysed with Spectralis-OCT and the Laguna ONhE application using the Topcon NW400 fundus camera. Topographic Hb values were correlated with OCT tissue thicknesses from Bruch's membrane. The neuroretinal rim volume (RV), the cup volume (CV) and their relation to the globin distribution function (GDF) index of Laguna ONhE were analysed. The results were applied to 1 163 241 optic nerve images obtained in a glaucoma screening setting. Differences in segmentation and the presence of vessels without local nutritional function are the main limitations of the comparison.

RESULTS

The correlation between local Hb density and the tissue thicknesses from Bruch's membrane was R=0.953 (p<0.0001). RV could be estimated from pixel-to-pixel Hb values with an R=0.650 (p<0.0001) and from six Laguna ONhE indices with an R=0.786 (p<0.0001). CV could be estimated with an R=0.762 (p<0.0001). RV had a mean value of 0.396 mm3 (SD=0.187) for positive GDF values and usually below 0.210 mm3 for negative GDF. The distribution of RV values in the screening series was congruent with that found in the prospective series, with a higher value in large nerves.

CONCLUSIONS

The volume and shape of the optic nerve tissue are closely related to its perfusion and can be deduced from it. The relationship between the RV and GDF is curvilinear and suggests that perfusion measurement may bring the diagnosis forward in earlier stages.

Assessment of Structural Progression in Glaucoma Through Automated Optic Nerve Head Hemoglobin Measurements

PRCIS

Automated optic nerve head hemoglobin measurements through change over time in the Globin Individual Pointer (GIP) index, provided by the Laguna ONhE software, can be useful to evaluate structural progression in glaucoma.

PURPOSE

To assess the performance of automated optic nerve head hemoglobin measurements (ONH Hb) for detection of structural progression in glaucoma patients using event analysis.

PATIENTS AND METHODS

Treated glaucoma patients were included in this cross-sectional study. Two experienced examiners classified patients into progressors and non-progressors (controls) based on serial color retinographies (CR). Progressors were then subdivided in structural changes of the neuroretinal rim (NR) or retinal nerve fiber layer (RNFL). Globin individual pointer (GIP) index, derived from ONH Hb measurements, was calculated for each CR using the Laguna ONhE software. Differences in GIP values, ​​between baseline and last visit CRs, were used to assess structural progression. Sensitivity at a fixed specificity (50%; median GIP difference in controls) and areas under receiver operating characteristic curves (AUROC) were calculated.

RESULTS

Eight-seven eyes (35 progressors and 52 controls) from 64 patients were enrolled. Mean GIP reduction over time was greater in progressors (-13.0±18.6) than controls (-2.9±10.4; P =0.001). In progressors, mean GIP reduction was greater in patients with NR changes (-19.6±19.5) than RNFL changes (-3.1±12.1; P =0.008). GIP difference correctly identified 69% of the progressors (AUROC: 0.66), being 76% of these progressions related to NR changes (AUROC: 0.76) and 57% to RNFL changes (AUROC: 0.52).

CONCLUSIONS

The GIP index, based on automated ONH Hb measurements demonstrated good sensitivity to differentiate progressors from controls, especially in cases in which progression was documented through structural NR changes. Using only 2 CRs and event analysis, GIP changes over time can be a useful screening tool to evaluate structural progression.

Automated Optic Nerve Head Hemoglobin Measurements versus General Ophthalmologists Evaluation to Differentiate Glaucomatous from Large Physiological Cupping: A Diagnostic Performance Comparative Study

Purpose

The aim of this study is to compare the diagnostic performance in differentiating patients with glaucoma from those with presumed large physiological optic disc cupping (LPC), using optic nerve head hemoglobin levels (ONH Hb), as a screening method, versus the evaluation of general ophthalmologists.

Patients and Methods

Twenty general ophthalmologists evaluated PowerPoint images of 40 patients with glaucoma and 40 presenting LPC. Presentation of patient's exams were distributed as follows: Group 1 (GI): color retinography (CR), Group 2 (GII): CR + visual field (VF), Group 3 (GIII): CR + optical coherence tomography (OCT), Group 4 (GIV): CR + VF + OCT. The Laguna ONhE software was used to estimate ONH Hb based on CR. Main outcomes were the comparison of sensitivity and accuracy between general ophthalmologists' evaluation and the glaucoma discriminant function (GDF) index from Laguna ONhE and also the agreement between examiners (Kappa statistics).

Results

Laguna ONhE GDF index demonstrated higher sensitivity values (GI- 90%; GII-90%; GIII-100%; GIV-100%) comparing to all groups (GI-59%; GII-86.5%; GIII-86.5%; GIV-68.5%). In GI, in which it was observed the worst accuracy result (64.8%), we found 75% for GDF. In GII, the accuracy was 81.3% and we found 55% for GDF. The highest agreement was in GII (Kappa=0.63; 95% CI=0.53-0.72), and the lowest in GI (Kappa=0.30; 95% CI=0.20-0.39).

Conclusion

Laguna ONhE software, a low-cost and non-invasive method, showed good sensitivity and great utility as a screening method in differentiating patients with glaucoma from those with LPC, compared with evaluation of general ophthalmologists.

Identification of Glaucoma in Diabetics Using the Laguna-ONhE Colourimetric Method and OCT Spectralis

BACKGROUND

Previous retrospective results are evaluated prospectively and blinded.

METHODS

A total of 221 eyes previously classified as normal (G1), 279 as moderate risk of glaucoma (G2) and 217 as high risk (G3) according to the Globin Discriminant Function (GDF) Laguna-ONhE index were examined with OCT Spectralis- Results: In G1, the Bruch's Membrane Opening Minimum Rim Width (BMO-MRW) was 332 ± 55 microns; in G2, it was 252 ± 47 (p < 0.0001); and in G3, 231 ± 44 (p < 0.0001). In G1, the 1% and 5% percentiles were 233 and 248, respectively; in G2, they were lower in 28.80% and 42.29% of cases, respectively; and in G3, in 50.23% and 63.59% of cases, respectively. Most of the cases were normal-tension glaucomas. Laguna-ONhE indices showed a curvilinear correlation with BMO-MRW results. The Retinal Nerve Fibre Layer (RNFL) showed a poor relationship with BMO. Assuming G1 to be truly normal, BMO-MRW would have a Receiver operating characteristic (ROC) curve area of 0.901 for G2 and G3 and 0.651 for RNFL. A significant reduction in pixels corresponding to vessels was found in G2 and G3 vs. G1 (p < 0.0001).

CONCLUSIONS

In some cases, these defects appear to be mainly glaucomatous, and in others, they are associated with diabetic microangiopathy. In normal tension glaucoma, RNFL defects may be less severe than those inside the nerve.

Agreement between Five Experts and the Laguna ONhE Automatic Colourimetric Application Interpreting the Glaucomatous Aspect of the Optic Nerve

BACKGROUND

Optic nerve head (ONH) interpretation is a glaucoma screening method which may be influenced by criteria variability. Laguna ONhE software is a low-cost and non-invasive method of ONH analysis.

METHODS

We analysed the results of the Laguna ONhE application, interpreting 552 ONH images from the ACRIMA database, publicly available on the Internet, and compared them with the opinion of five experts. Diagnostic agreement was investigated using Cohen's kappa (κ) with 95% confidence.

RESULTS

The kappa concordance index obtained with Laguna ONhE and the majority of the experts' criterion (0.77) was significantly higher compared to that obtained with ACRIMA and the majority of the experts' criterion (0.61). In 44.7% of the cases there was absolute agreement among the 5 experts and the Laguna ONhE program. Removing borderline cases from the analysis yielded increased diagnostic agreement (0.81). The area under the receiver operating characteristic (AUROC) of the Laguna ONhE program (0.953, p < 0.001) was not significantly different than AUROC of the majority of the experts' criterion (0.925, p < 0.001), p = 0.052. Individually obtained expert's AUROCs were significantly lower (0.636 to 0.913; p < 0.01).

CONCLUSIONS

Laguna ONhE's agreement with the experts is high, particularly where the diagnosis may be more obvious by the appearance of the ONH.

Glaucoma Incidence and Progression in Diabetics: The Canary Islands Study Using the Laguna ONhE Application

Background: Laguna ONhE provides a globin distribution function (GDF), in which a glaucoma discriminator based on deep learning plays an important role, and there is also an optimized globin individual pointer (GIP) for progression analysis. Methods: Signs of optic nerve glaucoma were identified in 1,124,885 fundus images from 203,115 diabetics obtained over 15 years and 117,813 control images. Results: A total of 743,696 images from 313,040 eyes of 173,661 diabetics were analysed. Some exclusions occurred due to excessive illumination, poor quality, or the absence of optic discs. Suspicion of glaucoma was reported in 6.70%, for an intended specificity of 99% (GDF < −15). More signs of glaucoma occur in diabetics as their years of disease increase, and after age 60, compared to controls. The GIP detected progression (p < 0.01) in 2.59% of cases with 4 controls and in 42.6% with 14 controls was higher in cases with lower GDF values. The GDF was corrected for the disc area and proved to be independent of it (r = 0.001925; p = 0.2814). Conclusions: The GDF index suggests a higher and increasing glaucoma probability in diabetics over time. Doubling the number of check-ups from four to eight increases the ability to detect GIP index progression by a factor of 5.