Acquired colour vision defects in glaucoma-their detection and clinical significance

Chromatic visual evoked potentials: A review of physiology, methods and clinical applications

Objective assessment of the visual system can be performed electrophysiologically using the visual evoked potential (VEP). In many clinical circumstances, this is performed using high contrast achromatic patterns or diffuse flash stimuli. These methods are clinically valuable but they may only assess a subset of possible physiological circuitries within the visual system, particularly those involved in achromatic (luminance) processing. The use of chromatic VEPs (cVEPs) in addition to standard VEPs can inform us of the function or dysfunction of chromatic pathways. The chromatic VEP has been well studied in human health and disease. Yet, to date our knowledge of their underlying mechanisms and applications remains limited. This likely reflects a heterogeneity in the methodology, analysis and conclusions of different works, which leads to ambiguity in their clinical use. This review sought to identify the primary methodologies employed for recording cVEPs. Furthermore cVEP maturation and application in understanding the function of the chromatic system under healthy and diseased conditions are reviewed. We first briefly describe the physiology of normal colour vision, before describing the methodologies and historical developments which have led to our understanding of cVEPs. We thereafter describe the expected maturation of the cVEP, followed by reviewing their application in several disorders: congenital colour vision deficiencies, retinal disease, glaucoma, optic nerve and neurological disorders, diabetes, amblyopia and dyslexia. We finalise the review with recommendations for testing and future directions.

Influence of Diabetes Mellitus on Glaucoma-Relevant Examination Results in Primary Open-Angle Glaucoma

Primary open-angle glaucoma (POAG) is no longer considered an isolated eye pressure-dependent optic neuropathy, but a neurodegenerative disease in which oxidative stress and neuroinflammation are prominent. These processes may be exacerbated by additional systemic diseases. The most common are arterial hypertension, dyslipidemia, and diabetes mellitus. Using diabetes mellitus as an example, it will be shown how far-reaching the influence of such a systemic disease can be on both the functional and the structural diagnostic methods for POAG. This knowledge is essential, since these interferences can lead to misinterpretations of POAG, which can also affect therapeutic decisions.

Democratizing Health Care in the Metaverse: How Video Games can Monitor Eye Conditions Using the Vision Performance Index: A Pilot Study

Objective

In a world where digital media is deeply engrained into our everyday lives, there lies an opportunity to leverage interactions with technology for health and wellness. The Vision Performance Index (VPI) leverages natural human-technology interaction to evaluate visual function using visual, cognitive, and motor psychometric data over 5 domains: field of view, accuracy, multitracking, endurance, and detection. The purpose of this study was to describe a novel method of evaluating holistic visual function through video game-derived VPI score data in patients with specific ocular pathology.

Design

Prospective comparative analysis.

Participants

Patients with dry eye, glaucoma, cataract, diabetic retinopathy (DR), age-related macular degeneration, and healthy individuals.

Methods

The Vizzario Inc software development kit was integrated into 2 video game applications, Balloon Pop and Picture Perfect, which allowed for generation of VPI scores. Study participants were instructed to play rounds of each video game, from which a VPI score was compiled.

Main Outcome Measures

The primary outcome was VPI overall score in each comparison group. Vision Performance Index component, subcomponent scores, and psychophysical inputs were also compared.

Results

Vision Performance Index scores were generated from 93 patients with macular degeneration (n = 10), cataract (n = 10), DR (n = 15), dry eye (n = 15), glaucoma (n = 16), and no ocular disease (n = 27). The VPI overall score was not significantly different across comparison groups. The VPI subcomponent "reaction accuracy" score was significantly greater in DR patients (106 ± 13.2) versus controls (96.9 ± 11.5), P = 0.0220. The VPI subcomponent "color detection" score was significantly lower in patients with DR (96.8 ± 2.5; p=0.0217) and glaucoma (98.5 ± 6.3; P = 0.0093) compared with controls (101 ± 11). Psychophysical measures were statistically significantly different from controls: proportion correct (lower in DR, age-related macular degeneration), contrast errors (higher in cataract, DR), and saturation errors (higher in dry eye).

Conclusions

Vision Performance Index scores can be generated from interactions of an ocular disease population with video games. The VPI may offer utility in monitoring select ocular diseases through evaluation of subcomponent and psychophysical input scores; however, future larger-scale studies must evaluate the validity of this tool.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Evaluation of color vision related quality of life changes due to cataract surgery

Questionnaires have been used as research tools to provide a standardized approach to assess quality of life at various time periods and populations. However, literature shows only a few articles about self-reported color vision changes. Our aim was to evaluate the subjective patient feelings before and after cataract surgery and compare the results with a color vision test result. Our method was as follows: 80 cataract patients filled out a modified color vision questionnaire and performed the Farnsworth-Munsell 100 Hue Color Vision Test (FM100) before, two weeks, and six months after cataract surgery. We analyzed the correlations between these two types of results, which reveal that FM100 hue performance and subjective perception improved after surgery. Additionally, subjective patient questionnaire scores correlate well with the FM100 test results before and two weeks after the cataract surgery, but this effect decreased with longer follow-up times. We conclude that subjective color vision changes can only be noticed at longer periods after the cataract surgery. Health care professionals can use this questionnaire to better understand the subjective feelings of patients and monitor their color vision sensitivity changes.

The presenting visual symptoms of optic chiasmal disease

Recognising optic chiasmal disease early is important in order to avoid irreversible visual loss and the potential risk of mortality for patients. Yet, there is frequently a delay in the initial diagnosis. Whilst the signs of optic chiasmal disease, particularly the perimetric findings, are well documented in the recent literature, the symptoms have been less well reported. Whilst some patients with optic chiasmal disease will be asymptomatic, many will complain of visual symptoms including symptomatic field defects, problems with central vision, difficulty with near tasks, binocular visual disturbances, colour vision disturbances, photophobia, phosphenes, glare, and rarely, oscillopsia and visual hallucinations. Others may have headache or the severe and sudden visual symptoms associated with pituitary apoplexy. The visual symptoms may be vague or non-specific, even when there are significant bitemporal visual field defects. We aim in this review to describe the presenting visual symptoms of optic chiasmal disease, and to illustrate these with selected qualitative descriptions from the literature. Our hope is that this will aid clinicians in eliciting a careful history of the sometimes subtle symptoms that may be present.

Delineating the Clinical Phenotype of Patients With the c.629C>G, p.Pro210Arg Mutation in Peripherin-2

Purpose

More than 200 different mutations in peripherin-2 (PRPH2) are associated with multiple subtypes of inherited retinal diseases (IRDs), including retinitis pigmentosa and cone or macular diseases. Our goal was to understand how the poorly characterized PRPH2 mutation p.Pro210Arg (P210R) affects visual function and retinal structure as well as gain insight into the mechanism driving the clinical pathology.

Methods

Eleven patients had clinical assessments including best-corrected visual acuity (BCVA), full field and multifocal electroretinography (ERG), static (spot size V) and kinetic perimetry (Octopus 900), and dark-adapted chromatic (DAC; Medmont; spot size V) perimetry. Images were acquired with the Optos ultra-wide field camera and spectral-domain optical coherence tomography (SD-OCT). Molecular characteristics of the P210R mutant protein were evaluated in vitro.

Results

Patients with the P210R mutation had BCVA (Snellen) ranging from 20/15 to 20/80. Perimetry showed a reduction in sensitivity, while ERG findings suggested that cone function was more impaired than rod function. Scotomas were identified corresponding to atrophic retinal lesions. Imaging revealed heterogeneous outer retinal changes such as hyperfluorescent flecks, hypo-autofluorescence (AF) regions of atrophy, and thinning of the photoreceptor layer on SD-OCT. In vitro findings suggested that P210R-Prph2 retains the ability to interact with binding partner Rom1 but abnormally accumulates in the endoplasmic reticulum (ER), suggesting the protein does not fold properly.

Conclusions

Rod and cone sensitivities were decreased in subjects with the P210R mutation in PRPH2. There was scotomatous vision loss that occurred within the macula, likely due to atrophy that occurs after drusen have formed and have begun to resolve. This suggests that although rod and cone photoreceptors are dependent on PRPH2, preventing blindness in this specific subgroup of patients could involve therapeutics that impede the formation or lifecycle of drusen.

Effects of acute high intraocular pressure on red-green and blue-yellow cortical color responses in non-human primates

Glaucoma is a leading cause of irreversible blindness worldwide, and intraocular pressure (IOP) is an established and modifiable risk factor for both chronic and acute glaucoma. The relationship between color vision deficits and chronic glaucoma has been described previously. However, the effects of acute glaucoma or acute primary angle closure, which has high prevalence in China, on color vision remains unclear. To address the above question, red-green or blue-yellow color responses in V1, V2, and V4 of seven rhesus macaques were monitored using intrinsic-signal optical imaging while monocular anterior chamber perfusions were performed to reversibly elevate IOP acutely over a clinically observed range of 30 to 90 mmHg. We found that the cortical population responses to both red-green and blue-yellow grating stimuli, systematically decreased as IOP increased from 30 to 90 mmHg. Although a similar decrement in magnitude was noted in V1, V2, and V4, blue-yellow responses were consistently more impaired than red-green responses at all levels of acute IOP elevation and in all monitored visual areas. This physiological study in non-human primates demonstrates that acute IOP elevations substantially depress the ability of the visual cortex to register color information. This effect is more severe for blue-yellow responses than for red-green responses, suggesting selective impairment of the koniocellular pathways compared with the parvocellular pathways. Together, we infer that blue-yellow color vision might be the most vulnerable visual function in acute glaucoma patients.

The Association Between Acquired Color Deficiency and PET Imaging of Neurodegeneration in Mild Cognitive Impairment and Alzheimer Disease

Purpose

To evaluate color vision changes and retinal processing of chromatic and luminance pathways in subjects with Alzheimer disease (AD) and mild cognitive impairment (MCI) compared with a matched control group and whether such changes are associated with impaired brain glucose metabolism and β-amyloid deposition in the brain.

Methods

We evaluated 13 patients with AD (72.4 ± 7.7 years), 23 patients with MCI (72.5 ± 5.5 years), and 18 controls of comparable age (P = 0.44) using Cambridge color test and the heterochromatic flicker ERG (HF-ERG). The Cambridge color test was performed using the trivector protocol to estimate the protan, deutan and tritan color confusion axes. HF-ERG responses were measured at a frequency of 12 Hz, which ERGs reflect chromatic activity, and at 36 Hz, reflecting luminance pathway. A study subsample was performed using neuropsychological assessments and positron emission tomography.

Results

Patients with AD presented higher mean values indicating poorer color discrimination for protan (P = 0.04) and deutan (P = 0.001) axes compared with the controls. Along the tritan axis, both patients with AD and patients with MCI showed decreased color vision (P = 0.001 and P = 0.001) compared with controls. The analyses from the HF-ERG protocol revealed no differences between the groups (P = 0.31 and P = 0.41). Diffuse color vision loss was found in individuals with signs of neurodegeneration (protan P = 0.002, deutan P = 0.003 and tritan P = 0.01), but not in individuals with signs of β-amyloid deposition only (protan P = 0.39, deutan P = 0.48, tritan P = 0.63), regardless of their clinical classification.

Conclusions

Here, patients with AD and patients with MCI present acquired color vision deficiency that may be linked with impaired brain metabolism.

Yield of investigations in patients with questionable nonglaucomatous optic neuropathy

OBJECTIVE

Nonglaucomatous optic neuropathy (NGON) may often be mistaken for normal-tension glaucoma. The distinction between these two entities is important in determining treatment, prognosis, and need for further investigations. We report characteristics of a cohort of patients referred for neuro-ophthalmologic consultation to distinguish between glaucomatous (GON) and NGON.

METHODS

Retrospective chart review of patients presenting to a tertiary neuro-ophthalmology practice investigated for GON versus NGON between 2018 and 2020. Patients were classified as GON or NGON based on presence of optic disc pallor, degree of cupping, central visual acuity, and/or when investigations yielded a cause of NGON.

RESULTS

Eighty-three patients were enrolled. Seventy-one patients (86%) were deemed to have possible NGON after initial evaluation and having undergone neuroimaging. Of these, 14 patients (19.7%) were determined to have NGON and 7 patients (9.9%) both GON and NGON. The most common causes of NGON were undetermined (8), previous optic neuritis (4), and neurovascular conflict (2). The yield of neuroimaging was low, with abnormalities seen in only 4 of 71 patients (5.6%). No patients with bilateral cupping and no relative afferent pupillary defect (RAPD) had abnormalities on imaging, and no patients with positive imaging required intervention. Patients with NGON had lower intraocular pressure and cup-to-disc ratio and usually had optic disc pallor (86%). Nerve fibre bundle defects were most common in both GON and NGON, with more nasal defects seen in GON.

CONCLUSIONS

When NGON resembles GON, the underlying cause is often undetermined, and the yield of neuroimaging is low. The yield of investigating patients with bilateral cupping and no RAPD for NGON is especially low.

Visual fields and optical coherence tomography (OCT) in neuro-ophthalmology: Structure-function correlation

Visual field (VF) testing is an essential component of the neurological examination. The differential diagnosis of VF defects depends on relating this measure of afferent visual function to the structure of the visual pathway and optical coherence tomography (OCT) is an invaluable tool for detailed structural evaluation of the optic nerve and retina. This review describes the ways in which interpretation of VF and OCT can be used together to increase the accuracy of the localization of lesions along the visual pathway. Lesions of the anterior visual pathway (originating in ganglion cells or nerve fibre layer of the retina or optic nerve) will typically produce defects that respect the horizontal midline, reflecting the arcuate path of the ganglion cell axons as they travel to the optic nerve. OCT of peripapillary retinal nerve fibre layer and ganglion cell complex (GCC) will typically demonstrate irreversible thinning in compressive and demyelinating lesions affecting anterior visual pathway. Chiasmal lesions produce highly localizable VF defects (junctional scotoma and bitemporal hemianopia) which correspond to the thinning of nasal portion of GCC. Lesions of the optic tract result in incongruous homonymous hemianopia on VF with corresponding hemianopic thinning on GCC developing within months. Lesions affecting optic radiations usually produce more congruous homonymous VF defects and can also produce homonymous thinning on GCC, however, this takes much longer to develop as trans-synaptic degeneration at the lateral geniculate body must occur.

Characteristics of Normal-tension Glaucoma Patients with Temporal Retinal Nerve Fibre Defects

Glaucomatous visual field (VF) damage usually involves in the Bjerrum area, which refers to outside the central 10° region. However, some reports suggest that structural damage to the macula occurs even in the early stages of glaucoma. We investigated the characteristics of normal tension glaucoma (NTG) patients with temporal retinal nerve fibre layer (RNFL) defects. Ninety eyes from 90 subjects including 30 normal eyes, 30 eyes of 30 patients with normal-tension glaucoma with temporal RNFL defects, and 30 eyes of 30 patients with normal-tension glaucoma with inferotemporal or superotemporal RNFL defects were enrolled. The best-corrected visual acuity (BCVA) decreased significantly in glaucomatous eyes with temporal RNFL defects as compared with in controls and glaucomatous eyes with inferotemporal or superotemporal RNFL defects. VF tests showed more frequent central or cecocentral VF defects involving the central 10° region in glaucomatous eyes with temporal RNFL defects. VF defects were more frequently detected on short-wavelength automated perimetry (SWAP). Eyes with temporal RNFL defects had generally reduced ganglion cell-inner plexiform layer (GCIPL) thickness. In addition, the BCVA, GCIPL thicknesses, and SWAP findings were significantly different in glaucoma patients with temporal RNFL defects according to their colour vision deficiency, not RNFL thickness or standard automated perimetry (SAP) results.

Measurable Aspects of the Retinal Neurovascular Unit in Diabetes, Glaucoma, and Controls

PURPOSE

To study the structural and angiographic optical coherence tomography (OCT) data of the macula from controls, patients with diabetes, and patients with glaucoma to evaluate neurovascular and structural relationships.

METHODS

This was a retrospective study of 89 eyes from 49 patients in a community-based retinal referral practice with diabetes, glaucoma, and normal controls. The patients were evaluated with OCT to include retinal nerve fiber layer (RNFL) thickness measurement and ganglion cell layer (GCL) volume determination. The vascular density of the radial peripapillary capillary network and the vascular plexuses in the macula were evaluated with OCT angiography. The main outcome measures were the data obtained per disease state and the interrelationships the data displayed.

RESULTS

The mean GCL volumes were significantly lower than the control group in both the diabetic (P = .016) and glaucoma (P < .001) groups. The difference between the diabetic and glaucoma groups was not significant (P = .052). The mean global vascular density was greater in the control group than the diabetic group (P = .002) and the glaucoma group (P < .001). The mean RNFL thicknesses were lowest in the glaucoma group. Both the diabetic and glaucoma groups had significantly lower radial peripapillary network and deep vascular plexus density values compared to controls.

CONCLUSIONS

Although there are important differences in disease pathogenesis between diabetes and glaucoma, they share certain similarities in the structural and angiographic abnormalities eventually produced. This suggests that, in addition to canonical pathways of disease, a component of both could represent neurodegenerative disease, offering the possibility for the development of new treatments. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Temporal Raphe Sign for Discrimination of Glaucoma from Optic Neuropathy in Eyes with Macular Ganglion Cell-Inner Plexiform Layer Thinning

PURPOSE

To evaluate the potential of the temporal raphe sign on the macular ganglion cell-inner plexiform layer (mGCIPL) thickness map for discriminating glaucomatous from nonglaucomatous optic neuropathy (NGON) in eyes with mGCIPL thinning.

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 175 eyes of 175 patients with mGCIPL thinning on Cirrus (Carl Zeiss Meditec, Dublin, CA) high-definition OCT were retrospectively included. Glaucoma specialists and neuro-ophthalmology specialists evaluated the patients' medical records for diagnosis of glaucomatous optic neuropathy (GON) or NGON. Finally, by consensus, 67 eyes with GON and 73 eyes with NGON were enrolled.

METHODS

A positive temporal raphe sign was declared in patients in whom there was a straight line longer than one-half of the length between the inner and outer annulus in the temporal elliptical area of the mGCIPL thickness map. Decision tree analysis was performed to formulate a diagnostic model.

MAIN OUTCOME MEASURES

Area under receiver operating characteristic curve (AUC) with sensitivity and specificity.

RESULTS

The temporal raphe sign was observed in 61 of 67 GON eyes (91.0%), but in only 21 of 73 NGON eyes (28.8%) (P < 0.001; chi-square test). On this basis, the diagnostic ability of the temporal raphe sign for discriminating GON from NGON was judged to be good (AUC, 0.811; 95% confidence interval, 0.749-0.874; sensitivity, 91.0%; specificity, 71.2%). The diagnostic performance of the decision tree-based model (AUC 0.879; 95% confidence interval, 0.824-0.933; sensitivity, 88.1%; specificity, 87.7%) was better than that of the temporal raphe sign or the relative afferent pupillary defect (RAPD) alone (P = 0.005, P < 0.001, respectively; DeLong's test). The decision tree model revealed the following: (1) If the temporal raphe sign is positive and the RAPD is absent, the case should be diagnosed as GON; (2) if the temporal raphe sign is absent regardless of the presence or absence of the RAPD, or both the temporal raphe sign and the RAPD are present, the case should be diagnosed as NGON.

CONCLUSIONS

In clinical practice, determining whether the temporal raphe sign appears on OCT macular scans can be a useful tool for discrimination of glaucomatous from nonglaucomatous mGCIPL thinning.

Color vision abnormalities in type II diabetes: Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study II report no 2

Purpose:

The purpose of this study is to assess color vision abnormalities in a cohort of subjects with type II diabetes and elucidate associated risk factors.

Methods:

Subjects were recruited from follow-up cohort of Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetics Study I. Six hundred and seventy-three eyes of 343 subjects were included from this population-based study. All subjects underwent detailed ophthalmic evaluation, including the Farnsworth-Munsell 100 hue test.

Results:

The prevalence of impaired color vision (ICV) was 43% (CI: 39.2–46.7). Risk factors for ICV were higher heart rate (odds ratio [OR]: 1.043, [1.023–1.064]) and a higher intraocular pressure (IOP) (OR: 1.086, [1.012–1.165]). Subjects with clinically significant macular edema (CSME) had three times higher chance of having ICV. C1, C2, and C3 are the commonly found Early Treatment Diabetic Retinopathy Study (ETDRS) patterns. The moment of inertia method showed that the angle did not reveal any specific pattern of color vision defect. Although the major and minor radii were high in those with ICV, we did not observe polarity. Confusion index was high in subjects with ICV, indicating a severe color vision defect.

Conclusions:

The prevalence of ICV was 43% among subjects with type II diabetes. The most commonly observed patterns were increasing severities of the blue–yellow defect on ETDRS patterns, but no specific pattern was observed at the moment of inertia analysis. The presence of CSME, a higher heart rate, and IOP was significant risk factors for ICV. This functional impairment in color vision could significantly contribute to morbidity among subjects with diabetes.

ACE

Colour can convey a mood or elicit a particular emotion and, in terms of web design, colour can influence attitudes, perceptions, and behaviours. However, many websites demonstrate inaccessible colour choices. Numerous online colour palette design tools only focus on assisting designers with either the aesthetics or accessibility of colours. With a user-centered design approach, we developed the Accessible Colour Evaluator (ACE, daprlab.com/ace) which enhances web developers’ and designers’ ability to balance aesthetic and accessibility constraints. We distributed an online questionnaire to 28 web developers and designers to understand their attitudes and utilisation of accessibility guidelines, as well as to gather initial design requirements for ACE. With this information, we created three low-fidelity paper prototypes that were used to create two high-fidelity prototypes. The high-fidelity prototypes were discussed with 4 web developers and designers during a design workshop, and their feedback was used to develop the final version of ACE. A comparative evaluation of ACE and three existing alternative tools was conducted with 10 new web developers and designers. All participants were able to complete a colour palette design task when using ACE and identified ACE as their most preferred tool. The mean scores for the six TLX measures show ACE as providing the best performance and causing the lowest frustration. Finally, we conducted a small focus group with 3 web developers and designers to gather qualitative feedback about ACE. Participants identified a number of ACE’s strengths and made suggestions for future extensions and improvements.

Impaired colour vision in workers exposed to organic solvents: A systematic review

OBJECTIVE

To evaluate recent evidence concerning the relationship between the exposure to organic solvents and the impairment of colour vision.

METHODS

A bibliographic search was conducted for scientific papers published in the last 15 years, in the LILACS, PubMed, Science Direct, EBSCO, and Cochrane databases that included observational studies assessing the relationship between impairment in colour vision and exposure to organic solvents.

RESULTS

Eleven studies were selected that were performed on an economically active population and used the Lanthony D-15 desaturated test (D-15d), measured the exposure to organic solvents, and included unexposed controls. It was found that there is a statistically significant relationship between the exposure to organic solvents and the presence of an impairment in colour vision.

CONCLUSIONS

The results support the hypothesis that exposure to organic solvents could induce acquired dyschromatopsia. The evaluation of colour vision with the D-15d test is simple and sensitive for diagnosis. More studies need to be conducted on this subject in order to better understand the relationship between impaired colour vision and more severe side effects caused by this exposure.

Defects of colour vision: A review of congenital and acquired colour vision deficiencies

Colour vision deficiencies (CVDs) can be categorised as being congenital or acquired. Some CVDs are already present at birth, as inherited conditions that are the result of changes at the photo-pigment level and are non-pathological, incurable and do not change over time. Examples are red-green defects which are inherited as an X-linked recessive trait. Acquired CVD develops secondary to ocular and systemic conditions or as a side effect of certain medications or sometimes toxic effects of chemicals, and trauma and ageing can also be important in some CVDs.

Ability of Bottle Cap Color to Facilitate Accurate Patient-Physician Communication Regarding Medication Identity in Patients with Glaucoma

PURPOSE

To determine the accuracy of patient-physician communication regarding topical ophthalmic medication use based on bottle cap color, particularly among individuals who may have acquired color vision deficiency from glaucoma.

DESIGN

Cross-sectional, clinical study.

PARTICIPANTS

Patients aged ≥18 years with primary open-angle, primary angle-closure, pseudoexfoliation, or pigment dispersion glaucoma, bilateral visual acuity of ≥20/400, and no concurrent conditions that may affect color vision.

METHODS

A total of 100 patients provided color descriptions of 11 distinct medication bottle caps. Color descriptors were then presented to 3 physicians. Physicians matched each color descriptor to the medication they thought the descriptor was describing.

MAIN OUTCOME MEASURES

Frequency of patient-physician agreement, occurring when all 3 physicians accurately matched the color descriptor to the correct medication. Multivariate regression models evaluated whether patient-physician agreement decreased with degree of better-eye visual field (VF) damage, color descriptor heterogeneity, or color vision deficiency, as determined by the Hardy-Rand-Rittler (HRR) score and Lanthony D15 color confusion index (D15 CCI).

RESULTS

Subjects had a mean age of 69 (±11) years, with VF mean deviation of -4.7 (±6.0) and -10.9 (±8.4) decibels (dB) in the better- and worse-seeing eyes, respectively. Patients produced 102 unique color descriptors to describe the colors of the 11 bottle caps. Among individual patients, the mean number of medications demonstrating agreement was 6.1/11 (55.5%). Agreement was less than 15% for 4 medications (prednisolone acetate [generic], betaxolol HCl [Betoptic; Alcon Laboratories Inc., Fort Worth, TX], brinzolamide/brimonidine [Simbrinza; Alcon Laboratories Inc.], and latanoprost [Xalatan; Pfizer, Inc., New York, NY]). Lower HRR scores and higher D15 CCI (both indicating worse color vision) were associated with greater VF damage (P < 0.001). Extent of color vision deficiency and color descriptor heterogeneity significantly predicted agreement in multivariate models (odds of agreement = 0.90 per 1 point decrement in HRR score, P < 0.001; odds of agreement = 0.30 for medications exhibiting high heterogeneity [≥11 descriptors], P = 0.007).

CONCLUSIONS

Physician understanding of patient medication use based solely on bottle cap color is frequently incorrect, particularly in patients with glaucoma who may have color vision deficiency. Errors based on communication using bottle cap color alone may be common and could lead to confusion and harm.

What do patients with glaucoma see? Visual symptoms reported by patients with glaucoma

Background:

Vision loss from glaucoma has traditionally been described as loss of “peripheral vision.” In this prospective study, we aimed to improve our clinical understanding of the visual symptoms caused by glaucoma by asking patients specific detailed questions about how they see.

Methods:

Patients who were clinically diagnosed with various types and stages of glaucoma were included. All had a comprehensive ocular examination, including Octopus visual field testing. Patients were excluded if they had other ocular conditions that affected their vision, including cornea, lens or retina pathologies. Patients responded to an oral questionnaire about their visual symptoms. We investigated the visual symptoms described by patients with glaucoma and correlated the severity of visual field loss with visual symptoms reported.

Results:

Ninety-nine patients completed the questionnaire. Most patients (76%) were diagnosed with primary open-angle glaucoma. The most common symptoms reported by all patients, including patients with early or moderate glaucoma, were needing more light and blurry vision. Patients with a greater amount of field loss (Octopus mean defect >+9.4 dB) were more likely to report difficulty seeing objects to one or both sides, as if looking through dirty glasses and trouble differentiating boundaries and colors.

Conclusions:

Vision loss in patients with glaucoma is not as simple as the traditional view of loss of peripheral vision. Needing more light and blurry vision were the most common symptoms reported by patients with glaucoma.

Are middle-age blood pressure levels related to color vision impairment? The Okubo Color Study

BACKGROUND

We sought to investigate the association between blood pressure levels and prevalence of acquired color vision impairment in middle-aged Japanese men.

METHODS

Participants underwent color vision testing, ophthalmological examination, standardized interview, physical record examination, and venous blood examination. Cardiovascular disease risk factors were determined based on blood and physical examination results and the interview. Logistic regression analysis was performed after adjusting for body mass index, systemic dyslipidemia, diabetes, cataract, glaucoma, smoking status, and drinking status.

RESULTS

Of 1,042 men, 872 were eligible for the study, 130 failed the Lanthony 15-hue desaturated panel (D-15 DS) diagnosed as acquired color vision impairment 15-hue, and 31 failed the Farnsworth-Munsell 100-hue test diagnosed as acquired color vision impairment 100-hue. Diastolic blood pressure was significantly correlated with both acquired color vision impairment in 100-hue patients (adjusted odds ratio (OR) for 10-mm Hg increases = 1.42; 95% confidence interval (CI) = 1.00-2.02) and acquired color vision impairment in 15-hue patients (adjusted OR for 10-mm Hg increases = 1.25; 95% CI = 1.04-1.51). The multiple-adjusted ORs for acquired color vision impairment 100-hue patients and acquired color vision impairment 15-hue patients were 7.13 (95% CI = 1.72-27.88) and 4.37 (95% CI = 1.69-11.03), respectively, for the highest blood pressure category (systolic blood pressure ≥ 160 and diastolic blood pressure ≥ 100 mm Hg) compared with those for the lowest blood pressure category (systolic blood pressure <120 and diastolic blood pressure <80 mm Hg). Tests for trends were significant (P < 0.05) in both analyses.

CONCLUSIONS

Hypertension in middle-aged men may negatively modify vision-associated neuronal function.

Reliability in perimetric multichannel contrast sensitivity measurements

BACKGROUND

In this study, the reliability of perimetric contrast sensitivity measurements favouring the achromatic, the red-green and the blue-yellow post-receptorial mechanisms was analysed.

METHODS

A new technique, multichannel ATD perimetry, provides spatial and temporal stimuli favouring the detection by an achromatic mechanism (A), from a magno or parvocellular origin or by a red-green (RG) chromatic mechanism, with a parvocellular origin or a blue-yellow (BY) mechanism, with a koniocellular origin. The repeatability and reproducibility of contrast sensitivity measurements with these stimuli were studied in a group of 40 healthy subjects. The analysis was carried out on 21 testing points within a 60° by 40° fovea-centred region of the visual field.

RESULTS

The within-observer repeatability for the four mechanisms studied is either good or excellent when the intra-class correlation coefficient (ICC) can be calculated. For the remaining points, the Friedman's test finds that the measurements are repeatable. The between-observer reproducibility was either excellent or good in cases where the ICC was applied and according to the Friedman's test all results were reproducible.

CONCLUSIONS

The results obtained showed good repeatability and reproducibility with A, RG and BY stimuli, although with BY stimuli repeatability is slightly worse. Future studies on the diagnostic validity of this device are based on the fact that changes of sensitivity can be compared by means of a visual single task, contrast sensitivity measurement and using a common metric.

A new computer-based Farnsworth Munsell 100-hue test for evaluation of color vision

To evaluate a computer-based Farnsworth-Munsell (FM) 100-hue test and compare it with a manual FM 100-hue test in normal and congenital color-deficient individuals. Fifty color defective subjects and 200 normal subjects with a best-corrected visual acuity ≥ 6/12 were compared using a standard manual FM 100-hue test and a computer-based FM 100-hue test under standard operating conditions as recommended by the manufacturer after initial trial testing. Parameters evaluated were total error scores (TES), type of defect and testing time. Pearson's correlation coefficient was used to determine the relationship between the test scores. Cohen's kappa was used to assess agreement of color defect classification between the two tests. A receiver operating characteristic curve was used to determine the optimal cut-off score for the computer-based FM 100-hue test. The mean time was 16 ± 1.5 (range 6-20) min for the manual FM 100-hue test and 7.4 ± 1.4 (range 5-13) min for the computer-based FM 100-hue test, thus reducing testing time to <50 % (p < 0.05). For grading color discrimination, Pearson's correlation coefficient for TES between the two tests was 0.91 (p < 0.001). For color defect classification, Cohen's agreement coefficient was 0.98 (p < 0.01). The computer-based FM 100-hue is an effective and rapid method for detecting, classifying and grading color vision anomalies.

Assessment of novel binocular colour, motion and contrast tests in glaucoma

The effects of glaucoma on binocular visual sensitivity for the detection of various stimulus attributes are investigated at the fovea and in four paracentral retinal regions. The study employed a number of visual stimuli designed to isolate the processing of various stimulus attributes. We measured absolute contrast detection thresholds and functional contrast sensitivity by using Landolt ring stimuli. This psychophysical Landolt C-based contrast test of detection and gap discrimination allowed us to test parafoveally at 6 ° from fixation and foveally by employing interleaved testing locations. First-order motion perception was examined by using moving stimuli embedded in static luminance contrast noise. Red/green (RG) and yellow/blue (YB) colour thresholds were measured with the Colour Assessment and Diagnosis (CAD) test, which utilises random dynamic luminance contrast noise (± 45 %) to ensure that only colour and not luminance signals are available for target detection. Subjects were normal controls (n = 65) and glaucoma patients with binocular visual field defects (n = 15) classified based on their Humphrey Field Analyzer mean deviation (MD) scores. The impairment of visual function varied depending on the stimulus attribute and location tested. Progression of loss was noted for all tests as the degree of glaucoma increased. For subjects with mild glaucoma (MD -0.01 dB to -6.00 dB) significantly more data points fell outside the normal age-representative range for RG colour thresholds than for any other visual test, followed by motion thresholds. This was particularly the case for the parafoveal data compared with the foveal data. Thus, a multifaceted measure of binocular visual performance, incorporating RG colour and motion test at multiple locations, might provide a better index for comparison with quality of life measures in glaucoma.

Eye movements during visual search in patients with glaucoma

Background

Glaucoma has been shown to lead to disability in many daily tasks including visual search. This study aims to determine whether the saccadic eye movements of people with glaucoma differ from those of people with normal vision, and to investigate the association between eye movements and impaired visual search.

Methods

Forty patients (mean age: 67 [SD: 9] years) with a range of glaucomatous visual field (VF) defects in both eyes (mean best eye mean deviation [MD]: –5.9 (SD: 5.4) dB) and 40 age-related people with normal vision (mean age: 66 [SD: 10] years) were timed as they searched for a series of target objects in computer displayed photographs of real world scenes. Eye movements were simultaneously recorded using an eye tracker. Average number of saccades per second, average saccade amplitude and average search duration across trials were recorded. These response variables were compared with measurements of VF and contrast sensitivity.

Results

The average rate of saccades made by the patient group was significantly smaller than the number made by controls during the visual search task (P = 0.02; mean reduction of 5.6% (95% CI: 0.1 to 10.4%). There was no difference in average saccade amplitude between the patients and the controls (P = 0.09). Average number of saccades was weakly correlated with aspects of visual function, with patients with worse contrast sensitivity (PR logCS; Spearman’s rho: 0.42; P = 0.006) and more severe VF defects (best eye MD; Spearman’s rho: 0.34; P = 0.037) tending to make less eye movements during the task. Average detection time in the search task was associated with the average rate of saccades in the patient group (Spearman’s rho = −0.65; P < 0.001) but this was not apparent in the controls.

Conclusions

The average rate of saccades made during visual search by this group of patients was fewer than those made by people with normal vision of a similar average age. There was wide variability in saccade rate in the patients but there was an association between an increase in this measure and better performance in the search task. Assessment of eye movements in individuals with glaucoma might provide insight into the functional deficits of the disease.

Long-term occupational exposure to organic solvents affects color vision, contrast sensitivity and visual fields

The purpose of this study was to evaluate the visual outcome of chronic occupational exposure to a mixture of organic solvents by measuring color discrimination, achromatic contrast sensitivity and visual fields in a group of gas station workers. We tested 25 workers (20 males) and 25 controls with no history of chronic exposure to solvents (10 males). All participants had normal ophthalmologic exams. Subjects had worked in gas stations on an average of 9.6±6.2 years. Color vision was evaluated with the Lanthony D15d and Cambridge Colour Test (CCT). Visual field assessment consisted of white-on-white 24–2 automatic perimetry (Humphrey II-750i). Contrast sensitivity was measured for sinusoidal gratings of 0.2, 0.5, 1.0, 2.0, 5.0, 10.0 and 20.0 cycles per degree (cpd). Results from both groups were compared using the Mann–Whitney U test. The number of errors in the D15d was higher for workers relative to controls (p<0.01). Their CCT color discrimination thresholds were elevated compared to the control group along the protan, deutan and tritan confusion axes (p<0.01), and their ellipse area and ellipticity were higher (p<0.01). Genetic analysis of subjects with very elevated color discrimination thresholds excluded congenital causes for the visual losses. Automated perimetry thresholds showed elevation in the 9°, 15° and 21° of eccentricity (p<0.01) and in MD and PSD indexes (p<0.01). Contrast sensitivity losses were found for all spatial frequencies measured (p<0.01) except for 0.5 cpd. Significant correlation was found between previous working years and deutan axis thresholds (rho = 0.59; p<0.05), indexes of the Lanthony D15d (rho = 0.52; p<0.05), perimetry results in the fovea (rho = −0.51; p<0.05) and at 3, 9 and 15 degrees of eccentricity (rho = −0.46; p<0.05). Extensive and diffuse visual changes were found, suggesting that specific occupational limits should be created.

Alterations of color vision and central visual field in patients with Vogt-Koyanagi-Harada syndrome

PURPOSE

To investigate the changes of color vision and central visual field in a cohort of patients with Vogt-Koyanagi-Harada (VKH) syndrome.

METHODS

Sixteen VKH patients (32 eyes) were enrolled in this study. All the patients were treated with immunosuppressive agents. The best visual acuity, visual field testing and color vision testing were available from the records in all these patients at different time points, i.e. before treatment and 1 month (±7 days), 3 months (±15 days), 6 months (±20 days) and 12 months (±30 days) after treatment.

RESULTS

All patients showed active intraocular inflammation at their first visit. A decreased visual acuity, abnormality of color vision and abnormal visual field were observed at presentation. Visual acuity and color vision rapidly improved at 1 and 3 months and gradually improved thereafter. Visual field defects significantly improved at 6 months and gradually improved thereafter. However, visual field defects were still observed in 27.5% of the tested patients following a 12-month treatment. Color vision returned to the normal level only in about one-third of these patients at this time point.

CONCLUSIONS

Visual function was severely impaired in VKH patients with active uveitis but rapidly improved following immunosuppressive therapy. Visual fields are much more severely affected by the disease than visual acuity and its improvement lagged behind that of visual acuity and color vision.

Métodos utilizados na avaliação psicofísica da visão de cores humana

A cor é um atributo perceptual que nos permite identificar e localizar padrões ambientais de mesmo brilho e constitui uma dimensão adicional na identificação de objetos, além da detecção de inúmeros outros atributos dos objetos em sua relação com a cena visual, como luminância, contraste, forma, movimento, textura, profundidade. Decorre daí a sua importância fundamental nas atividades desempenhadas pelos animais e pelos seres humanos em sua interação com o ambiente. A psicofísica visual preocupa-se com o estudo quantitativo da relação entre eventos físicos de estimulação sensorial e a resposta comportamental resultante desta estimulação, fornecendo dessa maneira meios de avaliar aspectos da visão humana, como a visão de cores. Este artigo tem o objetivo de mostrar diversas técnicas eficientes na avaliação da visão cromática humana através de métodos psicofísicos adaptativos.

Alzheimer's disease: visual system review

BACKGROUND

Ten million baby boomers in the United States will get Alzheimer's disease. Optometrists can benefit from understanding the impact the Alzheimer's disease process has on the visual system. This can result in more effective management of the condition and in more effective communication with members of the Alzheimer's disease multidisciplinary team.

METHODS

This is a review of the literature but by no means a completely exhaustive review. Alzheimer's disease is a complex disease. A rapidly expanding body of knowledge covers multiple disciplines.

RESULTS

The visual system shows deficits early in the degenerative process of Alzheimer's disease. Biomarkers through the visual system such as nerve fiber deficits, lens opacities, and functional losses in the magnocellular pathway, such as contrast sensitivity and temporal processing, may prove to not only help detect Alzheimer's disease early but also detect it before there are the classic cognitive and memory losses.

CONCLUSIONS

The effects of Alzheimer's disease are devastating. Optometrists, as primary care clinicians, can make critical contributions in the diagnosis, treatment, and management of this neurodegenerative disease.

Serum low-density lipoprotein cholesterol level is strong risk factor for acquired color vision impairment in young to middle-aged Japanese men: the Okubo Color Study Report 2

OBJECTIVE

To investigate associations between blood low-density lipoprotein cholesterol (LDL-C) levels and the prevalence of acquired color vision impairment (ACVI) in middle-aged Japanese men.

METHODS

Participants in this cross-sectional study underwent color vision testing, ophthalmic examination, a standardized interview and examination of venous blood samples. Ishihara plates, a Lanthony 15-hue desaturated panel, and Standard pseudoisochromatic Plates part 2 were used to examine color vision ability. The Farnsworth-Munsell 100-hue test was performed to define ACVI. Smoking status and alcohol intake were recorded during the interview. We performed logistic regression analysis adjusted for age, LDL-C level, systemic hypertension, diabetes, cataract, glaucoma, overweight, smoking status, and alcohol intake. Adjusted odds ratios for four LDL-C levels were calculated.

RESULTS

A total of 1042 men were enrolled, 872 participants were eligible for the study, and 31 subjects were diagnosed with ACVI. As compared to the lowest LDL-C category level (<100 mg/dl), the crude OR of ACVI was 3.85 (95% confidence interval [CI], 1.24-11.00) for the 2nd highest category (130-159 mg/dl), and 4.84 (95% CI, 1.42-16.43) for the highest level (>or=160 mg/dl). The multiple-adjusted ORs were 2.91 (95% CI, 0.87-9.70) for the 2nd highest category and 3.81 (95% CI, 1.03-14.05) for the highest level. Tests for trend were significant (P<0.05) in both analyses.

CONCLUSIONS

These findings suggested that the prevalence of ACVI is higher among middle-aged Japanese men with elevated LDL-C levels. These changes might be related to deteriorated neurologic function associated with lipid metabolite abnormalities.

Acquired color vision and visual field defects in patients with ocular hypertension and early glaucoma

PURPOSE

To study acquired color vision and visual field defects in patients with ocular hypertension (OH) and early glaucoma.

METHODS

In a prospective study we evaluated 99 eyes of 56 patients with OH without visual field defects and no hereditary color deficiencies, followed up for 4 to 6 years (mean = 4.7 +/- 0.6 years). Color vision defects were studied using a special computer program for Farnsworth-Munsell 100 hue test and visual field tests were performed with Humphrey analyzer using program 30-2. Both tests were repeated every six months.

RESULTS

In fifty-six eyes, glaucomatous defects were observed during the follow-up period. There was a statistically significant difference in total error score (TES) between eyes that eventually developed glaucoma (157.89 +/- 31.79) and OH eyes (75.51 +/- 31.57) at the first examination (t value 12.816, p < 0.001). At the same time visual field indices were within normal limits in both groups. In the glaucomatous eyes the earliest statistical significant change in TES was identified at the first year of follow-up and was -20.62 +/- 2.75 (t value 9.08, p < 0.001) while in OH eyes was -2.11 +/- 4.36 (t value 1.1, p = 0.276). Pearson's coefficient was high in all examinations and showed a direct correlation between TES and mean deviation and corrected pattern standard deviation in both groups.

CONCLUSION

Quantitative analysis of color vision defects provides the possibility of follow-up and can prove a useful means for detecting early glaucomatous changes in patients with normal visual fields.

Technical note: the effect of refractive blur on colour vision evaluated using the Cambridge Colour Test, the Ishihara Pseudoisochromatic Plates and the Farnsworth Munsell 100 Hue Test

The results of a prospective study examining the effect of refractive blur on colour vision performance in normal subjects measured with three different colour vision tests are reported. The Farnsworth Munsell 100 Hue (FM100) and Cambridge Colour Test (CCT) results were significantly affected at +6 D of spherical refractive blur, whereas those from the Ishihara Pseudoisochromatic Plate (IPP) test were not. In a clinical setting, correction of refractive error up to 3 D for colour vision testing with these tests may not be required. Poor colour vision should not be attributed solely to refractive causes of poor visual acuity (Snellen equivalent: >6/36). Fastest test times were achieved using IPP, followed by CCT.

Impairment in Color Perception in Migraine With and Without Aura

OBJECTIVE

To assess visual perception in 40 patients suffering from migraine with aura (MA), 40 patients suffering from migraine without aura (MO), and 40 controls.

BACKGROUND

Visual perception abnormalities are a common feature in both MA and MO.

METHODS

We performed luminance and color central perimetry. Black and white pattern reversal visual-evoked potentials were also assessed.

RESULTS

Luminance perimetry was similar in patients and controls. Color perimetry instead revealed an impairment in the perception of red ("quantitative perception index") in migraine patients; this impairment was more pronounced in patients with MA (P < .001) than in those with MO (P < .05) and was related to the degree of photophobia recorded before testing. A subgroup of MO patients who had a migraine attack shortly after being tested also displayed a marked impairment in the perception of blue. This subgroup of patients had a statistically significant (P < .001) lower perception of blue than the rest of the MO patients, who had a migraine attack later; they also had a high degree of unpleasant perceptions after testing. Black and white visual evoked potentials were similar in patients and controls.

CONCLUSION

The impairment in visual perception of red, which was more marked in MA than in MO patients, may be related to the degree of photophobia recorded before testing. The reduced perception of blue, which only occurred in a subgroup of MO patients in the premonitory phase of the migraine attack, probably occurs through mechanisms that involve dopaminergic function. We cannot exclude the possibility that the visual stimulations induced the migraine attack in this subgroup of MO patients shortly after they were tested.

Tilted disc syndrome and colour vision

PURPOSE

To study colour vision in patients with tilted disc syndrome.

METHODS

Colour vision was examined using Boström-Kugelberg (B-K) plates, Farnsworth-Munsell 100-hue test (FM-100) and Farnsworth panel D-15 and Lanthony desaturated panel tests.

RESULTS

A total of 35 eyes of 21 patients were examined. Seventeen eyes (49%) of 11 patients were found to have a colour vision defect in at least one eye. The severity of the colour vision defect differed between eyes for six of eight patients with bilateral tilted discs. In two of these patients, colour vision was normal in one eye. Seven patients had a unilateral tilted disc and three of these individuals had a colour vision defect in the affected eye. Of all eyes with a colour vision defect, a red-green defect was found in four eyes (24%), a blue defect in one eye (6%), and a mixed defect in 12 eyes (70%). Colour vision defects were not related to visual acuity or to severity of visual field defects.

CONCLUSIONS

This is the first report of colour vision defects in tilted disc syndrome. In the differential diagnosis of tilted disc syndrome, chiasmal lesions and glaucoma, the examination of colour vision may add valuable information. Further, it is recommended that young people with tilted disc syndrome undergo an examination of colour vision so that they can be given appropriate career guidance.

Relationship between visual field loss and contrast threshold elevation in glaucoma

BACKGROUND

There is a considerable body of literature which indicates that contrast thresholds for the detection of sinusoidal grating patterns are abnormally high in glaucoma, though just how these elevations are related to the location of visual field loss remains unknown. Our aim, therefore, has been to determine the relationship between contrast threshold elevation and visual field loss in corresponding regions of the peripheral visual field in glaucoma patients.

METHODS

Contrast thresholds were measured in arcuate regions of the superior, inferior, nasal and temporal visual field in response to laser interference fringes presented in the Maxwellian view. The display consisted of vertical green stationary laser interference fringes of spatial frequency 1.0 c deg(-1) which appeared in a rotatable viewing area in the form of a truncated quadrant extending from 10 to 20 degrees from fixation which was marked with a central fixation light. Results were obtained from 36 normal control subjects in order to provide a normal reference for 21 glaucoma patients and 5 OHT (ocular hypertensive) patients for whom full clinical data, including Friedmann visual fields, had been obtained.

RESULTS

Abnormally high contrast thresholds were identified in 20 out of 21 glaucoma patients and in 2 out of 5 OHT patients when compared with the 95% upper prediction limit for normal values from one eye of the 36 normal age-matched control subjects. Additionally, inter-ocular differences in contrast threshold were also abnormally high in 18 out of 20 glaucoma patients who had vision in both eyes compared with the 95% upper prediction limit. Correspondence between abnormally high contrast thresholds and visual field loss in the truncated quadrants was significant in 5 patients, borderline in 4 patients and absent in 9 patients.

CONCLUSION

While the glaucoma patients tested in our study invariably had abnormally high contrast thresholds in one or more of the truncated quadrants in at least one eye, reasonable correspondence with the location of the visual field loss only occurred in half the patients studied. Hence, while contrast threshold elevations are indicative of glaucomatous damage to vision, they are providing a different assessment of visual function from conventional visual field 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.

Human neurobehavioral effects of long-term exposure to styrene: a meta-analysis

Many reports in the literature suggest that long-term exposure to styrene may exert a variety of effects on the nervous system, including increased choice reaction time and decreased performance of color discrimination and color arrangement tasks. Sufficient information exists to perform a meta-analysis of these observations quantifying the relationships between exposure (estimated from biomarkers) and effects on two measures of central nervous system function: reaction time and color vision. To perform the meta-analysis, we pooled data into a single database for each end point. End-point data were transformed to a common metric of effect magnitude (percentage of baseline). We estimated styrene concentration from biomarkers of exposure and fitted linear least-squares equations to the pooled data to produce dose-effect relationships. Statistically significant relationships were demonstrated between cumulative styrene exposure and increased choice reaction time as well as increased color confusion index. Eight work-years of exposure to 20 ppm styrene was estimated to produce a 6.5% increase in choice reaction time, which has been shown to significantly increase the probability of automobile accidents. The same exposure history was predicted to increase the color confusion index as much as 1.7 additional years of age in men.

New Farnsworth-Munsell 100 hue test norms of normal observers for each year of age 5-22 and for age decades 30-70

AIMS

To provide normative data for chromatic discrimination on the Farnsworth-Munsell 100 hue test particularly for observers under 23 years of age.

METHODS

Normal observers were screened for congenital colour vision deficiencies using the Ishihara test leaving 382 observers.

RESULTS

New total error score (TES) norms (means and 95th percentiles) are presented for each year of age from 5-22 and for 10 year age groups from the 30s to the 70s. These norms are presented as actual values (TES) and also as square root values ( radical TES). Other data include partial error scores for red-green and blue-yellow axes discrimination.

CONCLUSION

This study provides the most detailed set of normative data to date. The data are also in agreement with other reports of chromatic discrimination, showing that the performance in this task varies as a U-shape function with age, the best being achieved at 19 years of age.

Color vision after laser in situ keratomileusis

PURPOSE

To evaluate the effect of laser in situ keratomileusis (LASIK) on color vision.

SETTING

Department of Ophthalmology, China Medical College Hospital, Taichung, Taiwan.

METHOD

This prospective study comprised consecutive patients having LASIK. Patients were eligible for inclusion if they had a best corrected visual acuity of 20/20 or better and a normal color vision test preoperatively and an uncorrected near visual acuity of 20/40 or better postoperatively. Color vision was tested using the Farnsworth-Munsell 100-hue test (FM 100 test) preoperatively and 1 day, 1 week, and 1 month postoperatively.

RESULTS

Twenty-nine eyes of 15 patients having LASIK were enrolled in the study. The mean patient age was 29.2 years +/- 2.9 (SD). The mean preoperative spherical equivalent refractive error was -5.6 +/- 1.8 diopters, and the mean preoperative error score of the FM 100 test was 3.79 +/- 1.55. After surgery, no significant change in the error score was observed at 1 day (4.30 +/- 1.07, P =.1039, paired t test), 1 week (3.72 +/- 1.25, P =.8125, paired t test), or 1 month (3.97 +/- 1.29, P =.6149, paired t test).

CONCLUSION

Laser in situ keratomileusis did not affect color vision evaluated by the FM 100 test.