The Perceived Bulbar Redness of Clinical Grading Scales

Improvement of objective ocular redness measured with Keratograph 5M in glaucoma patients after instilling brimonidine drops

OBJECTIVE

To compare objective ocular redness measured using OCULUS Keratograph 5 M before and after 0.2% brimonidine instillation in glaucoma patients under topical hypotensive treatment.

METHODS

60 eyes from 60 subjects diagnosed with glaucoma or ocular hypertension under hypotensive ocular topical treatment were analyzed. Basal Ophthalmological examination was performed.Outcome variables were OCULUS Keratograph 5 M redness scores (RS) before and after 0.2% brimonidine instillation; overall, bulbar temporal (BT), bulbar nasal (BN), limbar temporal (LT), and limbar nasal (LN); non-invasive average tear film breakup time (Nia-BUT), non-invasive first tear film breakup time (Nif-BUT) and meibography. In addition, the following clinical data were collected: intraocular pressure, type, duration, amount, and preservatives/or not of hypotensive treatment, fluorescein corneal staining score and lower tear meniscus height.

RESULTS

All eyes were under topical medication. All redness scores were reduced after brimonidine instillation, mean RS differences were BT 0.82 ± 0.62, BN hyperemia 1.03 ± 0.55, LN hyperemia 0.84 ± 0.49, LT hyperemia 0.71 ± 0.50 and total hyperemia 0.91 ± 0.52 (all p < 0.001). 30 min after brimonidine instillation mean overall RS reduction was 47.97 ± 12.39% (p < 0.001) and after 1 h there was a persistent reduction of overall RS of 45.92 ± 14.27% (p < 0.001). Hyperemia reduction was significant and comparable between preservative and preservative-free group 0.12 ± 0.14 (p > 0.392) and between patient with combination therapy and monotherapy 0.16 ± 0.14 (p > 0.258).

CONCLUSION

A significant reduction of conjunctival hyperemia was objectively found in glaucoma patients under topical hypotensive treatment before and after brimonidine instillation. Its fast and long-lasting effect may be useful preoperatively in glaucoma patients to reduce intraoperative bleeding and associated complications.

2022 Glenn A. Fry Award lecture: Enhancing clinical assessment for improved ophthalmic management

ABSTRACT

Detailed clinical assessment is critical to allow sensitive evaluation of the eye and its management. As technology advances, these assessment techniques can be adapted and refined to improve the detection of pathological changes of ocular tissue and their impact on visual function. Enhancements in optical medical devices including spectacle, contact, and intraocular lenses have allowed for a better understanding of the mechanism and amelioration of presbyopia and myopia control. Advancements in imaging technology have enabled improved quantification of the tear film and ocular surface, informing diagnosis and treatment strategies. Miniaturized electronics, large processing power, and in-built sensors in smartphones and tablets capacitate more portable assessment tools for clinicians, facilitate self-monitoring and treatment compliance, and aid communication with patients. This article gives an overview of how technology has been used in many areas of eye care to improve assessments and treatment and provides a snapshot of some of my studies validating and using technology to inform better evidence-based patient management.

Novel Application of Conjunctival Anterior Segment Optical Coherence Tomography Angiography to Assess Ocular Redness

PURPOSE

The aim of this study was to determine anterior segment optical coherence tomography angiography (AS-OCTA) parameters to assess ocular redness severity.

METHODS

AS-OCTA analyses of 60 eyes of 40 patients were grouped according to ocular redness stages using the 5-category validated bulbar redness scale in a cross-sectional retrospective study (groups 1-5). A subset of patients with slit-lamp photographs, total 35 eyes of 23 patients, were assessed with 10-category validated bulbar redness scale for comparison. AS-OCTA images of nasal and temporal bulbar conjunctiva were analyzed. Vessel density (VD) represented the blood flow pixels by the total pixels of image (%); vessel diameter index represented the VD by the skeletonized density; fractal dimension, measured with the box-count method, represented the vessel branching complexity. Averaged nasal and temporal parameters for each eye were correlated to validated bulbar redness scales.

RESULTS

There was no statistical difference between groups for age ( P = 0.118), sex ( P = 0.501), eye laterality (OD/OS; P = 0.111), or location (nasal/temporal; P = 0.932). In the 5-category scale, VD significantly increased from group 1 to 2 (31.5 ± 1.9% and 33.4 ± 2.2%, P = 0.023), 2 to 3 (36.0 ± 3.5%, P < 0.001), and 4 to 5 (40.2 ± 2.9 and 46.5 ± 2.8, P < 0.001). The correlations were 0.805 ( P < 0.001) and 0.893 ( P < 0.001) for the 5-category and 10-category scales, respectively. Vessel diameter index showed a significant increase from 1 to 2 (2.90 ± 0.17 and 3.00 ± 0.15; P = 0.004) and 4 to 5 (2.92 ± 0.31 and 3.33 ± 0.08; P = 0.001). The correlations were 0.550 ( P < 0.001) and 0.625 ( P < 0.001) for the respective scales. The fractal dimension showed no significant differences between subsequent groups. The correlations were 0.445 ( P < 0.001) and 0.583 ( P < 0.001), respectively.

CONCLUSIONS

Conjunctival AS-OCTA VD was the most reliable parameter to assess ocular redness.

Medmont Meridia™: Much More Than a Corneal Topographer

In recent years, advanced diagnostic instruments have become widely available in optometric practices, offering various functions that optimize clinical information gathering. This article focuses on the Medmont Meridia™, a state-of-the-art multipurpose diagnostic device with corneal topography and cutting-edge features. Corneal topography is pivotal in the early diagnosis of corneal disorders, determining baseline ocular surface assessment, helping in contact lens fitting, and monitoring ocular health over time. The Medmont Meridia boasts Placido-disc-based imaging with extensive corneal coverage. Furthermore, the Meridia accurately measures the horizontal visible iris diameter, pupil diameter, and palpebral fissure width, which assists in making contact lens parameter decisions. Additionally, it offers sagittal height data for scleral lens design and first lens selection, streamlining the fitting process. Beyond its topography capabilities, the Meridia excels as a comprehensive dry eye assessment tool. With features like tear meniscus height, tear film surface quality, and meibography capabilities, it aids in diagnosing dry eye and monitoring its progression. The device also provides customizable dry eye reports with integrated grading scales and questionnaires, making dry eye management, patient education, and compliance more accessible. In conclusion, the Medmont Meridia consolidates a multitude of examination tools in a single instrument, enhancing practice efficiency and elevating patient care and communication. Its versatility and accuracy make it an invaluable asset in optometric practices worldwide.

Canonical Grading Scales of Corneal and Conjunctival Staining Based on Psychophysical and Physical Attributes

Purpose

In this study, we apply psychophysical scaling principles based on physical (photometric) attributes of images to better understand the factors involved in clinician judgement of ocular surface staining and, using that knowledge, to develop photographic scales for the assessment of staining for dry eye (DE) and related conditions.

Methods

Subjects with noninfectious ocular surface staining were enrolled at five clinical sites. Following instillation of fluorescein, photographs of corneal staining were taken every 30 seconds for at least 5 minutes. The same procedure was followed for conjunctival staining after instillation of 2 µl of 1% lissamine green. A subset of the best corneal and bulbar conjunctival staining images were anonymized and a spectroradiometer measured photometric attributes (luminance and chromaticity). The images were scaled psychophysically by study investigators, who participated in constructing grading scales based on physical and psychophysical analyses. The final grading scales were refined following consultation with outside DE experts.

Results

Photographs were collected from 142 subjects (81% women), with an average age of 58 ± 17 years; 89% were diagnosed with DE. There was a monotonic relationship between between physical measurements and psychophysically scaled staining of both corneal (fluorescein) and bulbar (lissamine green) staining. Michelson contrast and u’ (chromaticity) accounted for 66% and 64% of the variability in the psychophysically scaled images of fluorescein corneal and lissamine green conjunctival staining, respectively.

Translational Relevance

This paper provides examples of the first ever clinically usable ocular surface staining scales validated using psychophysical scaling and the physical attributes (luminance and chromaticity) of the staining itself. In addition, it provides a generalizable method for the development of other clinical scales of ocular appearance.

A Review of Imaging Biomarkers of the Ocular Surface

A biomarker is a "characteristic that is measured as an indicator of normal biological processes, pathogenic processes, or responses to an exposure or intervention, including therapeutic interventions." Recently, calls for biomarkers for ocular surface diseases have increased, and advancements in imaging technologies have aided in allowing imaging biomarkers to serve as a potential solution for this need. This review focuses on the state of imaging biomarkers for ocular surface diseases, specifically non-invasive tear break-up time (NIBUT), tear meniscus measurement and corneal epithelial thickness with anterior segment optical coherence tomography (OCT), meibomian gland morphology with infrared meibography and in vivo confocal microscopy (IVCM), ocular redness with grading scales, and cellular corneal immune cells and nerve assessment by IVCM. Extensive literature review was performed for analytical and clinical validation that currently exists for potential imaging biomarkers. Our summary suggests that the reported analytical and clinical validation state for potential imaging biomarkers is broad, with some having good to excellent intra- and intergrader agreement to date. Examples of these include NIBUT for dry eye disease, ocular redness grading scales, and detection of corneal immune cells by IVCM for grading and monitoring inflammation. Further examples are nerve assessment by IVCM for monitoring severity of diabetes mellitus and neurotrophic keratitis, and corneal epithelial thickness assessment with anterior segment OCT for the diagnosis of early keratoconus. However, additional analytical validation for these biomarkers is required before clinical application as a biomarker.

Should Pearson's correlation coefficient be avoided?

PURPOSE

To survey the use of Pearson's correlation coefficient (r) and related statistical methods in the ophthalmic literature, to consider the limitations of r, and to suggest suitable alternative methods of analysis.

RECENT FINDINGS

Searching Ophthalmic and Physiological Optics (OPO), Optometry and Vision Science (OVS), and Clinical and Experimental Optometry (CXO) online archives using correlation and Pearson's r as search terms resulted in 4057 and 281 hits respectively. Coefficient of determination, r square, or r squared received fewer hits (65, 8, and 22 hits respectively). The assumption that r follows a bivariate normal distribution was rarely encountered (3 hits) although several studies applied Spearman's rank correlation (70 hits). The intra-class correlation coefficient (ICC) was widely used (178 hits), but fewer hits were recorded for partial correlation (43 hits) and multiple correlation (13) hits. There was little evidence that the problem of sample size was addressed in correlation studies.

SUMMARY

Investigators should be alert to whether: (1) the relationship between two variables could be non-linear, (2) the data are bivariate normal, (3) r accounts for a significant proportion of the variance in Y, (4) outliers are present, the data are clustered, or have a restricted range, (5) the sample size is appropriate, and (6) a significant correlation indicates causality. In addition, the number of significant digits used to express r and the problems of multiple testing should be addressed. The problems and limitations of r suggest a more cautious approach regarding its use and the application of alternative methods where appropriate.

Review and analysis of grading scales for ocular surface staining

Vital dye staining has been used for over a century to assess the severity of ocular surface disease. However, despite common usage, a universally accepted "gold standard" grading scale does not exist for corneal and conjunctival staining, which can impact the ability to diagnose and monitor ocular surface conditions such as dry eye. The Food and Drug Administration (FDA) and other international regulatory agencies rely on ocular surface staining as a primary endpoint for new drug approvals, so that absence of a "gold standard" scale may affect approval of new drug treatments. To begin to address this problem, we review existing, published grading scales in an integrated fashion, highlighting their differences and similarities to emphasize common themes and the methods and elements that are important in creating a standardized scale. Our goal is to aid the field in moving towards an accepted standardized grading scale for ocular surface staining that can be applied in clinic and research settings for a variety of ocular conditions.

Objective ocular surface tolerance in patients with glaucoma treated with topical preserved or unpreserved prostaglandin analogues

Purpose:

Preservatives in glaucoma medications have been associated with ocular toxicity. We compared ocular signs and symptoms in patients with open-angle glaucoma or ocular hypertension treated in monotherapy with preserved or preservative-free prostaglandin analogues.

Methods:

Observational cross-sectional clinical study in real life. 82 patients treated for at least 6 months with prostaglandin analogue were assessed for intraocular pressure, ocular symptoms and ocular signs including conjunctival hyperaemia, tear break-up time and tear meniscus height measured using objective and non-invasive methods (OCULUS Keratograph 5M). Patients presenting with symptoms of ocular toxicity with preserved prostaglandin analogues were switched to preservative-free latanoprost, and a second assessment was processed 6 months after.

Results:

At inclusion, 30 (36.6%) patients were treated with preservative-free latanoprost, 25 (30.5%) with preserved latanoprost, 16 (19.5%) with preserved travoprost and 11 (13.4%) with preserved bimatoprost. Patients treated with preservative-free latanoprost reported significantly less ocular symptoms upon instillation (mainly burning) and between instillations than patients treated with preserved prostaglandin analogues. The mean conjunctival hyperaemia (limbal + bulbar) was significantly lower with preservative-free latanoprost (2.08 ± 0.55) compared to preserved latanoprost (2.50 ± 0.7, p = 0.0085), preserved travoprost (2.67 ± 0.82, p = 0.0083) and preserved bimatoprost (2.68 ± 0.67, p = 0.0041). There were no relevant between-group differences in mean tear meniscus height and break-up time. Ocular symptoms and conjunctival hyperaemia improved when preserved prostaglandin analogues were switched to preservative-free latanoprost for 6 months while intraocular pressure reduction was maintained.

Conclusion:

Overall, this study suggests a better subjective and objective ocular tolerance when patients were treated with preservative-free latanoprost than with other preserved prostaglandin analogues monotherapy. Switching to preservative-free latanoprost maintained intraocular pressure at the same level as preservative prostaglandin analogue, but improved ocular surface tolerance.

Assessment of ocular redness measurements obtained with keratograph 5M and correlation with subjective grading scales

OBJECTIVE

To examine correlations between ocular redness scores provided by the Keratograph 5M and those determined using two image-based grading scales.

METHODS

Observational prospective cross-sectional study. Two hundred and twenty six eyes of two hundred and twenty six participants (175 patients using anti-glaucoma eye drops and 51 subjects untreated). All subjects were scored automatically using the keratograph 5M. These redness scores (RS) were then correlated with the gradings provided by the Efron and McMonnies/Chapman-Davies scale (MC-D) scales (two observers).

RESULTS

Excellent reproducibility was observed for both the Efron (weighted K=0.897, 95% CI 0.823-0.904) and MC-D (weighted K=0.783, 95% CI 0.752-0.795) scales. Keratograph RS and the scores obtained with both Efron (Spearman's Rho=0.43, P<0.001) and MC-D (Spearman's Rho=0.48, P<0.001) scales were significantly correlated. RS for the bulbar and limbal - nasal and temporal quadrants also correlated moderately with the two subjective scales. Through Bland Altman analysis, poor agreement was detected between the objective and subjective methods: agreement values for the Efron scale or MC-D scale (matching scorers between observers) versus overall RS showed high biases (-15.58 and -22.05 respectively) and wide limits of agreement (LOA) (-46.169 to 15.005 and -52.534 to 8.19 respectively). Lowest bias was observed between temporal limbal RS and Observer 2 Efron score (-0.04).

CONCLUSIONS

Although it emerged as a reliable objective method, the keratograph 5M overestimated the scores compared with the subjective grading scales when used to grade the degree of ocular redness. Therefore, they should not be interchangeable methods.

A new scale for the assessment of conjunctival bulbar redness

PURPOSE

Current scales for assessment of bulbar conjunctival redness have limitations for evaluating digital images. We developed a scale suited for evaluating digital images and compared it to the Validated Bulbar Redness (VBR) scale.

METHODS

From a digital image database of 4889 color corrected bulbar conjunctival images, we identified 20 images with varied degrees of redness. These images, ten each of nasal and temporal views, constitute the Digital Bulbar Redness (DBR) scale. The chromaticity of these images was assessed with an established image processing algorithm. Using 100 unique, randomly selected images from the database, three trained, non-physician graders applied the DBR scale and printed VBR scale. Agreement was assessed with weighted Kappa statistics (Kw).

RESULTS

The DBR scale scores provide linear increments of 10 from 10-100 when redness is measured objectively with an established image processing algorithm. Exact agreement of all graders was 38% and agreement with no more than a difference of ten units between graders was 91%. Kw for agreement between any two graders ranged from 0.57 to 0.73 for the DBR scale and from 0.38 to 0.66 for the VBR scale. The DBR scale allowed direct comparison of digital to digital images, could be used in dim lighting, had both temporal and nasal conjunctival reference images, and permitted viewing reference and test images at the same magnification.

CONCLUSION

The novel DBR scale, with its objective linear chromatic steps, demonstrated improved reproducibility, fewer visualization artifacts and improved ease of use over the VBR scale for assessing conjunctival redness.

Factors Affecting Microvascular Responses in the Bulbar Conjunctiva in Habitual Contact Lens Wearers

Purpose

To investigate the factors affecting microvascular responses in the bulbar conjunctiva of habitual contact lens (HCL) wearers.

Methods

A functional slit-lamp biomicroscope (FSLB) was used to image the temporal bulbar conjunctiva of habitual contact lens (HCL) wearers and non-contact lens (NCL) wearers. The vessel diameters and blood flow velocities (BFVs) were measured. Fractal analysis using Dbox as vessel density and D0 as vessel complexity were used to quantitatively analyze the microvascular network. One eye each of 91 NCL wearers and 75 HCL wearers was imaged.

Results

The BFV of NCL wearers was 0.50 ± 0.14 mm/s, which was negatively correlated with age (r = -0.22, P < 0.05). The BFV, vessel diameter, Dbox, and D0 of HCL wearers was significantly higher than NCL wearers (P < 0.05). In these HCL wearers, BFVs were positively correlated with contact lens (CL) hours of wear per day and CL days of wear per week. BFV, Dbox, and D0 were not related to CL years of wear, CL power, CL base curve, and CL diameter (P > 0.05).

Conclusions

Vascular responses on the bulbar conjunctiva occurred in HCL wearers and appeared to be unrelated to sex or age, CL years of wear, and lens parameters, indicating that wearing a CL itself may be the predominant factor inducing these responses.

Ocular Redness Measured with the Keratograph 5M in Patients Using Anti-Glaucoma Eye Drops

PURPOSE

To examine correlations between ocular redness measured with the new topographer Keratograph 5M and the use of topical anti-glaucoma medication.

METHODS

A total of 211 eyes of 211 patients with open-angle glaucoma or ocular hypertension on topical medication and 51 eyes of 51 healthy volunteers were recruited over 10 months. Outcome variables were keratograph redness scores (RS): overall, bulbar temporal (BT), bulbar nasal (BN), limbar temporal (LT), and limbar nasal (LN). In each subject, we also recorded the intraocular pressure-lowering eye drops used, daily doses and daily and cumulative preservative concentrations, fluorescein corneal staining score (OXFORD), lower tear meniscus height (Fourier-domain OCT), non-invasive tear film breakup time (Keratograph 5M), and ocular surface disease questionnaire index (OSDI).

RESULTS

Higher RS were recorded in the medication than control group (P < 0.01 all scores). Within the medication group, older patients returned greater RS (P < 0.05 all scores). Prostaglandin was a strong predictor of higher scores, except LN RS. A higher OSDI was associated with a higher LN RS (β = 0.007; P < 0.05), while the use of β-blockers was linked to a lower LN RS (β = -0.225; P < 0.05). The use of ≥3 daily eye drops with preservative gave rise to a higher BN RS and ≥3 daily eye drops to a higher LN RS (β = 0.366, P < 0.01; β = 0.296, P < 0.05, respectively).

CONCLUSION

Keratograph 5M can objectively detect the hyperaemia induced by glaucoma medication. The factors contributing to ocular redness were advanced age, more daily eye drops (nasal sectors), a higher OSDI, and prostaglandin as the medication used.

Prediction of Changes in Visual Acuity and Contrast Sensitivity Function by Tissue Redness after Pterygium Surgery

PURPOSE

The goal of this study was to predict visual acuity (VA) and contrast sensitivity function (CSF) with tissue redness grading after pterygium surgery.

MATERIALS AND METHODS

A total of 67 primary pterygium participants were selected from patients who visited an ophthalmology clinic. We developed a semi-automated computer program to measure the pterygium fibrovascular redness from digital pterygium images. The final outcome of this software is a continuous scale grading of 1 (minimum redness) to 3 (maximum redness). The region of interest (ROI) was selected manually using the software. Reliability was determined by repeat grading of all 67 images, and its association with CSF and VA was examined.

RESULTS

The mean and standard deviation of redness of the pterygium fibrovascular images was 1.88 ± 0.55. Intra-grader and inter-grader reliability estimates were high with intraclass correlation ranging from 0.97 to 0.98. The new grading was positively associated with CSF (p < 0.01) and VA (p < 0.01). The redness grading was able to predict 25% and 23% of the variance in the CSF and the VA, respectively.

CONCLUSIONS

The new grading of pterygium fibrovascular redness can be reliably measured from digital images and showed a good correlation with CSF and VA. The redness grading can be used in addition to the existing pterygium grading.

Assessing ocular bulbar redness: a comparison of methods

PURPOSE

We consider whether quantification of ocular bulbar redness, using image processing of relative Red-channel activity (Red-value), can be applied to a clinical sample and how this approach compares to an automated bulbar redness grading technique (Oculus Keratograph 5M, R-scan).

METHODS

Red-values from dry eye patients (n = 25) were determined using image processing of digital photographs over the nasal bulbar conjunctiva. Red-values were compared with subjective grades from six clinicians who graded the images using the IER scale. We considered the level of agreement between the Red-value and automated bulbar redness scores from the commercial instrument (R-scan). Scoring variability for each technique was assessed using the geometric coefficient of variation (gCoV, %). Agreement between techniques was considered with Bland-Altman analyses.

RESULTS

Red-values showed a strong linear relationship (R(2) = 0.99) to the R-scan. The Red-value had least variability (gCoV = 0.97%, 95% CI: 0.76-1.35%). The IER grade showed a linear relationship with Red-value (R(2) = 0.99), bound by a floor effect; it did not discriminate changes in redness below a threshold of 1.75 units (Red-value = 33.0%), after which it paralleled the redness returned by the R-scan. Intra-method variability for the redness returned by the R-scan (gCoV = 9.84%, 95% CI: 7.60-13.94%) and IER grades (gCoV = 7.30%, 95% CI: 1.73-10.31%) was similar (p > 0.05). Bland-Altman analysis showed the R-scan was consistently biased towards lower absolute redness scores than the IER.

CONCLUSIONS

Digital imaging processing, using relative Red-channel activity, was the least variable of the three techniques. The R-scan and IER showed similar intra-observer variability. The linear relationship between R-scan and Red-value suggests that the R-scan could be derived using similar methods.

A randomized phase I clinical study of cis-urocanic acid eye drops in healthy adult subjects

PURPOSE

To evaluate safety, ocular tolerability and pharmacokinetics of 0.5% and 2.5% cis-urocanic acid (cis-UCA) eye drops.

METHODS

In this phase I, double-blinded, placebo-controlled trial, 37 healthy volunteers were randomized to three treatment arms: 0.5% cis-UCA (12 subjects), 2.5% cis-UCA (12 subjects) and placebo eye drops (13 subjects). In the first part, the subjects were dosed topically on a randomized eye with one drop three times at 7 ± 1 hr intervals during 1 day. In the second part, the subjects self-administered three daily drops at 7 ± 1 hr intervals on both eyes for 14 days. Physical examination of the eyes was performed seven times during the study. Tolerability of cis-UCA was assessed by ocular comfort rating questionnaire. Pharmacokinetic blood and urine samples were analysed under good laboratory practice (GLP).

RESULTS

All subjects completed both parts of the study. There were no significant adverse events (AEs). The most common treatment-related ocular AE was eye irritation (62.2% of subjects). Cis-UCA concentrations in plasma remained below the limit of quantification (0.195 μg/ml) in all but two subjects. The fraction of the administered drug excreted into urine over the total collection period ranged from 3.2% to 61.6% of the last dose and from 1.1% to 20.5% of the daily dose.

CONCLUSIONS

Topical ocular administration of cis-UCA solution is safe and apart from mild- and short-lasting eye irritation after administration well tolerated in healthy adult subjects. Topical ocular dosing leads to transient systemic exposure to cis-UCA that does not cause systemic AEs.

The Measurement of Bulbar Hyperemia: Challenges and Pitfalls

Purpose

To review methods of assessing bulbar redness, particularly with respect to the practicality of comparing different rating systems.

Methods

The published literature was reviewed and discussed by a panel of experts and a narrative review prepared.

Results

Bulbar hyperemia is a common clinical sign and an important indicator of ocular disease. As bulbar hyperemia is a frequent side effect of topical glaucoma medications, accurate objective measurement is important to allow comparison of clinical studies. A number of different measurement systems have evolved to allow quantification of subjectively assessed redness to be rendered into a form that allows between-treatment comparisons and longitudinal changes in both clinical research and practice. Whereas widespread use of image-based rating scales has improved the assessment of bulbar redness in clinical practice and clinical research, these techniques are less than ideal. The scales are subject to an intrinsic subjectivity and are suboptimal in differentiating the physiologic phenomenon of bulbar hyperemia. There is also a degree of interobserver and intraobserver variation; in some studies, average variation in scores exceed half the extent of the whole scale. Moreover, a lack of interscale validation has led to confusion in comparing the results from clinical studies that use different scales. In a recent series of studies, cross-calibration between the various scales in use has been attempted.

Conclusions

Whereas naive comparisons between the results obtained in studies using different bulbar redness scales can lead to erroneous conclusions, the tools exist to permit meaningful comparisons between rating systems and scales.

Evaluation of regional bulbar redness using an image-based objective method

AIM

To develop an image-based objective method to precisely evaluate regional ocular bulbar injection.

METHODS

Six healthy adult volunteers were photographed in four orientations (superior, inferior, nasal and temporal sides) with and without stimulating eye drops. Six line segments (covering 30°) were drawn 4mm away from the limbus on each image using ImageJ software. The graph peaks, which were derived from the areas under the line segments and corresponded to the cross-sectional grey-level of the vessels, were analyzed to obtain peak area, peak height/width (PH/PW), and peak numbers. Different-sized areas were selected to calculate the pixels based on the edge-detection algorithm. Also, conjunctival and superficial scleral vessels were analyzed separately.

RESULTS

This method had a smaller coefficient of variation, especially for PH/PW, in all four orientations. Hyperaemia parameters changed the least after challenging in the superior region. Moreover, 95% of the PH/PW ratios were greater than 0.87 in conjunctival vessels and less than 1.00 in superficial scleral vessels. PH/PW significantly increased in conjunctival vessels and changed less in superficial scleral vessels.

CONCLUSION

A new method of objectively assessing bulbar injection based on ocular surface images was developed. This method can be used to quantify ocular regional injection and to distinguish the superficial scleral and conjunctival vessels.

Automated grading system for evaluation of ocular redness associated with dry eye

Background

We have observed that dry eye redness is characterized by a prominence of fine horizontal conjunctival vessels in the exposed ocular surface of the interpalpebral fissure, and have incorporated this feature into the grading of redness in clinical studies of dry eye.

Aim

To develop an automated method of grading dry eye-associated ocular redness in order to expand on the clinical grading system currently used.

Methods

Ninety nine images from 26 dry eye subjects were evaluated by five graders using a 0–4 (in 0.5 increments) dry eye redness (Ora Calibra™ Dry Eye Redness Scale [OCDER]) scale. For the automated method, the Opencv computer vision library was used to develop software for calculating redness and horizontal conjunctival vessels (noted as “horizontality”). From original photograph, the region of interest (ROI) was selected manually using the open source ImageJ software. Total average redness intensity (Com-Red) was calculated as a single channel 8-bit image as R – 0.83G – 0.17B, where R, G and B were the respective intensities of the red, green and blue channels. The location of vessels was detected by normalizing the blue channel and selecting pixels with an intensity of less than 97% of the mean. The horizontal component (Com-Hor) was calculated by the first order Sobel derivative in the vertical direction and the score was calculated as the average blue channel image intensity of this vertical derivative. Pearson correlation coefficients, accuracy and concordance correlation coefficients (CCC) were calculated after regression and standardized regression of the dataset.

Results

The agreement (both Pearson’s and CCC) among investigators using the OCDER scale was 0.67, while the agreement of investigator to computer was 0.76. A multiple regression using both redness and horizontality improved the agreement CCC from 0.66 and 0.69 to 0.76, demonstrating the contribution of vessel geometry to the overall grade. Computer analysis of a given image has 100% repeatability and zero variability from session to session.

Conclusion

This objective means of grading ocular redness in a unified fashion has potential significance as a new clinical endpoint. In comparisons between computer and investigator, computer grading proved to be more reliable than another investigator using the OCDER scale. The best fitting model based on the present sample, and usable for future studies, was C4=−12.24+2.12C2HOR+0.88C2RED:C4 is the predicted investigator grade, and C2HOR and C2RED are logarithmic transformations of the computer calculated parameters COM-Hor and COM-Red. Considering the superior repeatability, computer automated grading might be preferable to investigator grading in multicentered dry eye studies in which the subtle differences in redness incurred by treatment have been historically difficult to define.