The clinical assessment of colour discrimination in senile macular degeneration

Color Vision and Microperimetry Changes in Nonexudative Age-Related Macular Degeneration After Risuteganib Treatment: Exploratory Endpoints in a Multicenter Phase 2a Double-Masked, Randomized, Sham-Controlled, Crossover Clinical Trial

BACKGROUND AND OBJECTIVE

To explore the association between best-corrected visual acuity (BCVA) improvement and changes in microperimetry (MP) and color vision in patients with nonexudative age-related macular degeneration following administration of two 1.0-mg intravitreal doses of risuteganib.

PATIENTS AND METHODS

In a phase 2a, prospective, double-masked, sham-controlled study, eyes with nonexudative age-related macular degeneration and Early Treatment Diabetic Retinopathy Study BCVA between 20/40 and 20/200 were randomized to intravitreal risuteganib (1.0 mg) or sham injection. The risuteganib group received a second 1.0-mg dose, and patients in the sham group crossed over to receive 1.0 mg of risuteganib at week 16. Exploratory endpoints included changes in color vision and mesopic MP.

RESULTS

Thirty-nine patients (risuteganib, n = 25; sham, n = 14) completed the study. There was a significant (P < .05) correlation between BCVA and the total error score (TES) for both Lanthony and Hue Style. Confusion index was close to the criterion for significance (P = .056) in the risuteganib group. All color vision metrics demonstrated a trend toward improvement in risuteganib responders (BCVA letter gain ≥8 letters) and no change in the nonresponders, with significant differences seen in confusion index between the risuteganib and control group (P = .0493) and between responders and nonresponders (P = .0478). MP showed that risuteganib responders improved in mean sensitivity and change in number of loci ≤11 dB and ≤0 dB, whereas nonresponders worsened.

CONCLUSION

All color vision and MP parameters tested trended toward improvement in risuteganib-treated patients and risuteganib responders. Statistically significant improvement was evident in two metrics: confusion index (in risuteganib-treated patients and responders) and number of loci with decreased sensitivity (in responders). A significant correlation between BCVA and both TES Lanthony and TES Hue Style in risuteganib patients provides concurrent evidence of objective and subjective improvement of retinal function. [Ophthalmic Surg Lasers Imaging Retina 2022;53:430-438.].

Assessment of age‐related maculopathy using subjective vision tests

This paper reviews non-standard, clinical vision tests that may be used to detect the earliest visual loss in age-related maculopathy (ARM), before fundus changes are detected. We recommend a clinical test battery for all patients aged 60 years and older, comprising low luminance/low contrast (SKILL) VA or low contrast VA, desaturated D-15 colour vision assessment, flicker perimetry, glare recovery and dark adaptation if possible, together with conventional assessments of case history, ophthalmoscopy and high contrast visual acuity (VA) for the detection and diagnosis of ARM. Reading rate is also discussed as a potential indicator of early visual loss. For monitoring the progressive visual loss in age-related macular degeneration (AMD) and determining the requirements for optometric vision rehabilitation, we recommend more conventional clinical vision tests of distance and near visual acuity, reading rate, the effects of varying illumination and a functional central visual field assessment.

Color vision deficits in intermediate age-related macular degeneration

PURPOSE

To assess the effect of intermediate age-related macular degeneration (AMD) on foveal cone-contrast thresholds.

METHODS

We measured L-M and S-cone-contrast thresholds in subjects with intermediate AMD (n = 10) and age-matched control subjects (n = 10). Monocular, foveal 3-degree Gaussian blobs (600-millisecond raised cosine) were presented at 16 cone ratios throughout L-, M-, and S-cone space, and threshold contours were modeled with probability summation between two independent detection mechanisms. The role that preretinal absorption plays in aging was also evaluated by simulation with FG15 and neutral-density filters.

RESULTS

Aging results in loss of neural sensitivity, not explained by lens changes. On average, intermediate AMD was associated with reduced sensitivity in both color and luminance channels (p < 0.05) that appeared to indicate greater involvement of S-cones. When data were normalized to age-expected values, the changes to cone sensitivity were shown to be consistent (∼200% loss) across L-M, M-L, and S-cone mechanisms. In comparison, the luminance (L + M) mechanism showed relative sparing (155% loss, p < 0.05).

CONCLUSIONS

Eyes with the same phenotype of intermediate AMD can have varying degrees of color threshold loss. Functional markers enhance the clinical definition of disease expression in AMD.

Introducing a new computer-based test for the clinical evaluation of color discrimination

PURPOSE

To evaluate the Portal color sort test (PCST), a new computer-based test of color vision, by comparing it with a series of clinical tests of color vision in normal and color deficient subjects.

DESIGN

Prospective clinical laboratory study.

METHODS

Fifty-nine subjects with normal trichromatic vision or with congenital color vision defects underwent a series of color vision tests that included the 15-plate Ishihara test, the D-15 Farnsworth-Munsell test (D-15), the Farnsworth-Munsell 100-Hue test (FM 100-Hue), and the PCST under rigorous standardized conditions, as recommended by the respective manufacturers. The PCST generates a numerical discrimination score comparable to the FM 100-Hue.

RESULTS

To test validity, discrimination scores generated by the PCST were compared with scores on the FM 100-Hue. The Spearman rank correlation between discrimination scores on the FM 100-Hue and the PCST was 0.8 (P < .001). Reliability was assessed by asking patients to retake the PCST at a later sitting. Patients retaking the PCST achieved similar scores on their second sitting as on the first. The correlation in the score between the two tests was 0.7 (95% confidence interval [CI]: 0.4-0.9, P < .001). Median (quartiles) time to complete the PCST was 3.1 minutes. This was faster than the FM 100-Hue time (P < .001), but slower than both the Ishihara and the D-15 (both P < .001).

CONCLUSIONS

This study suggests that the PCST, a test of color vision deficiency, can be used effectively and reliably as a tool for screening (comparable to the Ishihara plates and the D-15) and grading (comparable to the FM 100-Hue) color discrimination ability.

Visual function and dysfunction in early and late age-related maculopathy

Late age-related maculopathy (ARM) is responsible for the majority of blind registrations in the Western world among persons over 50 years of age. It has devastating effects on quality of life and independence and is becoming a major public health concern. Current treatment options are limited and most aim to slow progression rather than restore vision; therefore, early detection to identify those patients most suitable for these interventions is essential. In this work, we review the literature encompassing the investigation of visual function in ARM in order to highlight those visual function parameters which are affected very early in the disease process. We pay particular attention to measures of acuity, contrast sensitivity (CS), cone function, electrophysiology, visual adaptation, central visual field sensitivity and metamorphopsia. We also consider the impact of bilateral late ARM on visual function as well as the relationship between measures of vision function and self-reported visual functioning. Much interest has centred on the identification of functional changes which may predict progression to neovascular disease; therefore, we outline the longitudinal studies, which to date have reported dark-adaptation time, short-wavelength cone sensitivity, colour-match area effect, dark-adapted foveal sensitivity, foveal flicker sensitivity, slow recovery from glare and slower foveal electroretinogram implicit time as functional risk factors for the development of neovascular disease. Despite progress in this area, we emphasise the need for longitudinal studies designed in light of developments in disease classification and retinal imaging, which would ensure the correct classification of cases and controls, and provide increased understanding of the natural course and progression of the disease and further elucidate the structure-function relationships in this devastating disorder.

The reliability of the Lanthony Desaturated D-15 test

PURPOSE

The Lanthony Desaturated Panel D-15 has been used to measure fine color discrimination for congenital and acquired color vision defects. This study investigated the test-retest reliability of the test using an intertest interval of approximately 1 month.

METHODS

One hundred twenty-six color vision normals (mean age = 34.5 years) were administered several color vision tests, including the Lanthony Desaturated D-15. Normal color vision status was confirmed using the anomaloscope and HRR color plates. The color vision tests were readministered 3 to 6 weeks after initial testing. The results of the Lanthony test were expressed using the color confusion index of Bowman. The difference in Color Confusion Index (CCI) between the two administrations was calculated and used to determine the intraclass correlation coefficient.

RESULTS

The overall mean CCI for the two administrations for these subjects was 1.11 +/- 0.136. The mean difference in CCI score between test administrations was -0.02 +/- 0.128. There was a strong correlation between the absolute value of the difference in CCI and the mean CCI for each subject (r = 0.51, p < 0.0001). The intraclass correlation coefficient was 0.56 (95% confidence interval, 0.43-0.67).

CONCLUSIONS

Although the Lanthony Desaturated D-15 test can be used to assess fine color discrimination, there is considerable within-subject variability in test results. The intraclass correlation coefficient is less than that recommended for use in clinical testing or research. Clinicians should consider at least three administrations of the test at each sitting to ensure precision and we recommend taking the mean of those three tests.

A fast system for reporting the Farnsworth-Munsell 100-hue colour vision test

We have developed a system for rapidly reporting the Farnsworth-Munsell (FM) 100-hue test using a personal computer and a bar code scanner. The computer generated report duplicates the conventional manual report of the FM 100-hue test so is very familiar to ophthalmologists and optometrists. The new system has proved to be of great assistance both in saving time and in eliminating arithmetic errors in the scoring calculations. The scanner technique produces two reports, one for each eye, within 4 min of the patient completing the test. This compares with the 60 min required by the conventional manual reporting system. In addition, it also gives a statistical analysis of the results in accordance with Verriest norms. The program is very versatile and user friendly, achieving a standard not present in the other FM 100-hue computerised systems currently available. As a consequence it makes this valuable diagnostic test much more accessible to patients and clinicians.

Long-term tamoxifen citrate use and potential ocular toxicity

PURPOSE

To estimate the prevalence of abnormalities in visual function and ocular structures associated with the long-term use of tamoxifen citrate.

METHODS

A single-masked, cross-sectional study involving multiple community and institutional ophthalmologic departments was conducted with a volunteer sample of 303 women with breast cancer currently taking part in a randomized clinical trial to determine the efficacy of tamoxifen (20 mg/day) in preventing recurrences. Participants included women who had never been on drug (n=85); women who had taken tamoxifen for an average of 4.8 years, then been off the drug for an average of 2.7 years (n=140); and women who had been on tamoxifen continuously for an average of 7.8 years (n=78). Women were evaluated by questionnaire, psychophysical testing, and clinical examination to determine any abnormalities in visual function and the comparative prevalences of corneal, lens, retinal, and optic nerve pathology.

RESULTS

There were no cases of vision-threatening ocular toxicity among the tamoxifen-treated participants. Compared with nontreated participants, the tamoxifen-treated women had no differences in the activities of daily vision, visual acuity measurements, or other tests of visual function except for color screening. Intraretinal crystals (odds ratio [OR]=3.58, P=.178) and posterior subcapsular opacities (OR=4.03, P=.034) were more frequent in the tamoxifen-treated group.

CONCLUSIONS

Women should have a thorough baseline ophthalmic evaluation within the first year of initiating tamoxifen therapy and receive appropriate follow-up evaluations.

A new colour vision test for clinical use

Several tests are available for assessing colour vision but they can be expensive, complicated or too time consuming to perform. We have produced a new plate test based on pseudoisochromatic principles. The test, using an error score, examines both the red-green and blue-yellow axes, with four levels of difficulty for each axis. Results from a pilot study show that error scores from congenital red-green blind subjects are significantly higher than those of age-matched controls (p < 0.01) only when using the red-green plates and not the blue-yellow plates. In optic neuritis patients, error scores using both the red-green and blue-yellow plates were significantly higher than those of controls throughout the 6 month follow-up. The test, including scoring, takes 6 minutes to complete. These preliminary results suggest that the new test is effective for screening congenital red-green blindness and monitoring colour vision defects in acquired diseases such as optic neuritis.

Modelling sensitivity losses in ocular disorders: colour vision anomalies following intense blue-light exposure in monkeys

The effects of prolonged exposure to intense, short-wavelength light were studied in monkeys through the measurement of increment-threshold spectral sensitivity (ITSS) and threshold-versus-intensity (TVI) functions using a behavioural method. The long-term effect of intense blue-light exposure was to induce a short-wavelength (SW) sensitivity loss which did not depend on the intensity or chromatic composition of the adapting field. The TVI curves for short wavelength stimuli revealed an increase in test threshold without changes in field sensitivity. Since this SW sensitivity loss may generalize to characteristic colour vision defects found in many outer retinal diseases, models of acquired alterations of colour vision mechanisms are considered. These models describe probable changes in ITSS functions and TVI curves in diseases affecting the inner or outer retina as well as changes in dark adaptation.

Age-related maculopathy. I: A review of its morphology and effects on visual function

Age-related maculopathy (ARM) is a leading cause of permanent vision loss in elderly people. ARM therefore constitutes an important public health problem which will increase in magnitude as the number of aged people in the general population becomes greater. The consequences of this condition are exacerbated by the fact that treatment, especially of the atrophic form of the disease, is ineffective. While laser photocoagulation may be helpful in the exudative form of ARM, there is often an inexorable progression towards severe vision loss in these patients. Therefore considerable attention needs to be paid to the aetiology of ARM, the potential for its prevention or delayed onset and its recognition through functional disturbances. This is the first of three papers dealing with ARM and its effects on visual function. We review its morphology and the visual disturbances that may ensue. The second and third papers will discuss the nature and detection of the central visual field loss due to ARM.

Computerized scoring and graphing of the Farnsworth-Munsell 100-hue color vision test

The Farnsworth-Munsell 100-hue test is a sensitive and accurate test of color discrimination. A major disadvantage of the test is the laborious and time-consuming calculation needed to score the results and plot them on a chart for interpretation. We present a computer program, written in Microsoft's BASIC language, that performs the calculation and reports both the individual color cap error scores (from which the graph is plotted) and the total error score. If used with an IBM personal computer (or compatible) capable of graphics, the program plots a graph in a modified polar coordinate format that can be printed on a dot-matrix printer.

A method for quantitative scoring of the Farnsworth Panel D-15

The Farnsworth Dichotomous test or Panel D-15 is used extensively for the evaluation of colour discrimination in congenital and acquired colour vision defects. This qualitative assessment of colour vision defect type and severity is based on the hue confusions which are represented diagrammatically on the Panel D-15 score sheet. This paper presents a new proposal for quantitatively scoring the Panel D-15 based on those hue confusions made by the subject. Such a quantitative score can be used to establish relationships with other visual functions or experimental conditions. The application of the scoring technique to clinical results is illustrated.

Sahlgren's saturation test for detecting and grading acquired dyschromatopsia

A new sorting test requires only two minutes for quantitative estimation of saturation thresholds for bluish pigment colors. The test is highly sensitive to and specific for differences between normal subjects and individuals with acquired color vision defects. When combined with Ishihara's pseudo-isochromatic plates, it discriminates between congenital and acquired dyschromatopsias and identifies subjects with combined defects.