Effects of several coloured interventions on reading performance in age-related macular degeneration (ARMD)

A literature review revealed that very little work has been conducted to investigate the possible benefits of coloured interventions on reading performance in low vision due to ARMD, under conditions that are similar to the real world reading environment. Further studies on the use of colour, as a rehabilitative intervention in low vision would therefore be useful. A series of objective, subject based, age-similar controlled experiments were used to address the primary aims. Trends in some of the ARMD data suggested better reading performance with blue or green illuminance but there were also some individuals who performed better with yellow, or with illuminance of reduced intensity. Statistically, better reading in general occurred with a specialised yellow photochromic lens and also a clear lens than with a fixed lens or a neutral density filter. No reading advantage was gained from using the coloured screen facility of a video-magnifier. Some subjects with low vision were found to have co-existent binocular vision anomalies, which may have caused reading difficulties similar to those produced by ARMD. Some individuals with ARMD benefited from the use of increased local illuminance produced by either a standard tungsten or compact fluorescent lamp. No reading improvement occurred with a daylight simulation tungsten lamp. The Intuitive Colorimeter® can be used to detect and map out colour vision discrimination deficiency in ARMD and the Humphrey 630 Visual Field Analyser can be used to analyse the biocular visual field in subjects with ARMD. Some experiments highlighted a positive effect of a blue intervention in reading with ARMD.

Functional and perceived benefits of wearing coloured filters by patients with age-related macular degeneration

Background: The aim was to investigate the visual effect of coloured filters compared to transmission-matched neutral density filters, in patients with dry age-related macular degeneration. Methods: Visual acuity (VA, logMAR), contrast sensitivity (Pelli-Robson) and colour vision (D15) were recorded for 39 patients (average age 79.1 ± 7.2 years) with age-related macular degeneration, both in the presence and absence of glare from a fluorescent source. Patients then chose their preferred coloured and matched neutral density transmission filters (NoIR). Visual function tests were repeated with the chosen filters, both in the presence and absence of glare from the fluorescent source. Patients trialled the two filters for two weeks each, in random order. Following the trial of each filter, a telephone questionnaire was completed. Results: VA and contrast sensitivity were unaffected by the coloured filters but reduced through the neutral density filters (p < 0.01). VA and contrast sensitivity were reduced by similar amounts, following the introduction of the glare source, both in the presence and absence of filters (p < 0.001). Colour vision error scores were increased following the introduction of a neutral density filter (from 177.6 ± 60.2 to 251.9 ± 115.2) and still further through coloured filters (275.1 ± 50.8; p < 0.001). In the absence of any filter, colour vision error scores increased by 29.1 ± 55.60 units in the presence of glare (F2,107 = 3.9, p = 0.02); however, there was little change in colour vision error scores, in the presence of glare, with either the neutral density or coloured filters. Questionnaires indicated that patients tended to gain more benefit from the coloured filters. Conclusions: Coloured filters had minimal impact on VA and contrast sensitivity in patients with age-related macular degeneration; however, they caused a small reduction in objective colour vision, although this was not registered subjectively by patients. Patients indicated that they received more benefit from the coloured filters compared with neutral density filters. © 2013 The Authors © 2013 Optometrists Association Australia.

The effects of coloured light filter overlays on reading rates in age-related macular degeneration

Purpose: To determine the effect of coloured light filter overlays on reading rates for people with age-related macular degeneration (AMD). Method: Using a prospective clinical trial design, we examined the null hypothesis that coloured light filter overlays do not improve reading rates in AMD when compared to a clear filter. Reading rates for 12 subjects with non-exudative AMD, associated with a relative scotoma and central fixation (mean age 81 years, SD 5.07 years) were determined using the Rate of Reading Test® (printed, nonsense, lower case sans serif, stationary text) with 10 different, coloured light filter overlays (Intuitive Overlays®; figures in brackets are percentage transmission values); rose (78%), pink (78%), purple (67%), aqua (81%), blue (74%), lime-green (86%), mint-green (85%), yellow (93%), orange (83%) and grey (71%). A clear overlay (Roscolene # 00) (360 cdm-2) with 100% transmittance was used as a control. Results: ANOVA indicated that there was no statistically significant difference in reading rates with the coloured light filter overlays compared to the clear filter. Furthermore, chi-squared analysis indicated that the rose, purple and blue filters had a significantly poorer overall ranking in terms of reading rates compared to the other coloured and clear light filters. Conclusion: Coloured light filter overlays are unlikely to provide a clinically significant improvement in reading rates for people with non-exudative AMD associated with a relative scotoma and central fixation. Copyright © Acta Ophthalmol Scand 2004.

Pupil responses associated with coloured afterimages are mediated by the magno-cellular pathway

Sustained fixation of a bright coloured stimulus will, on extinction of the stimulus and continued steady fixation, induce an afterimage whose colour is complementary to that of the initial stimulus; an effect thought to be caused by fatigue of cones and/or of cone-opponent processes to different colours. However, to date, very little is known about the specific pathway that causes the coloured afterimage. Using isoluminant coloured stimuli recent studies have shown that pupil constriction is induced by onset and offset of the stimulus, the latter being attributed specifically to the subsequent emergence of the coloured afterimage. The aim of the study was to investigate how the offset pupillary constriction is generated in terms of input signals from discrete functional elements of the magno- and/or parvo-cellular pathways, which are known principally to convey, respectively, luminance and colour signals. Changes in pupil size were monitored continuously by digital analysis of an infra-red image of the pupil while observers viewed isoluminant green pulsed, ramped or luminance masked stimuli presented on a computer monitor. It was found that the amplitude of the offset pupillary constriction decreases when a pulsed stimulus is replaced by a temporally ramped stimulus and is eliminated by a luminance mask. These findings indicate for the first time that pupillary constriction associated with a coloured afterimage is mediated by the magno-cellular pathway. © 2003 Elsevier Science Ltd. All rights reserved.

Benefit of coloured lenses for age-related macular degeneration

Purpose: To evaluate and compare the functional and perceived benefits of wearing coloured lenses by patients with age-related macular degeneration (ARMD). Method: Ten subjects with early ARMD and five elderly controls wore a selection of NoIR wrap-around coloured lenses (yellow 29.7% light transmission, orange 22.9%, red 16.8% and grey 10.3%), each for a duration of 7 days. Contrast sensitivity, colour vision, visual acuity, the effect of glare and peripheral sensitivity were measured for each lens and compared with a control (no lens) condition. Subjective ratings of visual performance were also scored. Results: Compared with the no filter condition, red and grey lenses reduced contrast sensitivity whereas yellow and orange lenses increased contrast sensitivity. These objective changes were supported by subjective ratings in subjects with ARMD. Grey lenses reduced the loss of contrast sensitivity usually suffered in the presence of glare, whereas visual acuity and peripheral sensitivity decreased with red lenses. Colour vision became distorted with red lenses in control subjects, but was relatively unaffected by the use of coloured lenses in subjects with ARMD. Conclusions: The subjective benefit of coloured lenses appears to be due to a minor enhancement of contrast sensitivity. © 2002 The College of Optometrists.

Equitably coloured balanced incomplete block designs

In this thesis we determine necessary and sufficient conditions for the existence of an equitably ℓ-colourable balanced incomplete block design for any positive integer ℓ > 2. In particular, we present a method for constructing non-trivial equitably ℓ-colourable BIBDs and prove that these designs are the only non-trivial equitably ℓ-colourable BIBDs that exist. We also observe that every equitable ℓ-colouring of a BIBD yields both an equalised ℓ-colouring and a proper 2-colouring of the same BIBD. We also discuss generalisations of these concepts including open questions for further research. The main results presented in this thesis also appear in [7].

Covering Dimension of C*-Algebras and 2-Coloured Classification

Peer reviewed

Assessment of Activity of 'Transparent and Clear' and 'Opaque and Highly Coloured' Photocatalytic Samples using a Fluorescent Photocatalytic Activity Indicator Ink, FPaii.

The photocatalytic activity of self-cleaning glass is assessed using a resazurin (Rz) photocatalyst activity indicator ink, i.e. Rz paii, via both the rate of change in the colour of the ink (blue to pink), R(Abs), and the rate of change in the fluorescence intensity, R(Fl), (λ(excitation) = 593 nm; λ(emission) = 639 nm) of the ink. In both cases the kinetics are zero order. Additional work with a range of glass samples of different photocatalytic activity reveal R(Abs) is directly related to R(Fl), thereby showing that the latter, like the former, can be used to provide a measure of the photocatalytic activity of the sample under test. The measured value of R(Fl) is found to be the same for 5 pieces of, otherwise identical, selfcleaning glass with: black, red, blue, yellow and no coloured tape stuck to their backs, which demonstrates that R(Fl) measurements can be used to measure photocatalytic activity under conditions of high colour and opacity under which R(Abs) cannot be measured. The relevance of this novel, fluorescence-based paii to the assessment of the activity of highly coloured, opaque photocatalytic samples, such as paints and tiles, is discussed briefly.