Journal of Neurology, Neurosurgery, and Psychiatry, 1974, 37, 1265-1272

'Flight of colours' in lesions of the visual system'

MARTIN FELDMAN, LEO TODMAN, AND MORRIS B. BENDER2

From the Department of Neurology, The Mount Sinai School of Medicine, New York, U.S.A.

SYNOPSIS A bright pocket flashlight was directed into one eye for 10 seconds; the subject thenclosed the eyelids and reported the sequence of after-image colours observed. Lesions of the visualsystem which compromised bilateral central colour vision also reduced or abolished the 'flight ofcolours'. This simple bedside test of each eye independently is of value in detecting mild defects ofcentral vision.

After we see an intense light such as an ignitedflashbulb or gaze at the sun for a few seconds,there is a fairly predictable sequence of visualevents known as visual after-images. An initialmomentary feeling of 'visual confusion', the'dazzling period', is followed by the appearanceof, usually, a clear light blue or purple disc whichchanges to a golden yellow, then green, thenpurple, then bluish green all within a matter ofseconds. This procession or 'flight of colours'continues to recur over a period of severalminutes.Although the entire visual system participates

in the formation and perception of these after-images, the changes are said to originate in theretina and are elaborated upon centrally. Manyinvestigators attribute the formation of after-images to photochemistry in the retina (Brindley,1959, 1962), while others attribute it to neuralafter-discharges (Marriott, 1965). The alterationsin sensation are likely to be related to photo-products formed by the bleaching of visual pig-ments (Brindley, 1962). Although the phenome-non of flight of colours in after-images has beenstudied qualitatively and quantitatively in thenormal subject (Berry, 1922; Washburn, 1925;Weve, 1925; Berry, 1927; Judd, 1927; Berry andImus, 1935; Feinbloom, 1938; Helmholtz,1963), there are few studies on visual after-images in patients with lesions at different levelsof the visual system (Bender and Teuber, 1946;Bender and Kahn, 1949).1 This work was supported in part by U.S.P.H.S. Grant EY-570.2 Reprint requests to: Dr Morris B. Bender, Mount Sinai School ofMedicine, I East 100th Street, New York, N.Y. 10029, U.S.A.

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METHODS

Patients with lesions at different levels of the visualsystem and normal subjects were studied for theappearance of a 'flight of colours' after an intenselight stimulus to each eye. The subject was placed ina dimly lit room for five minutes before the lightstimulus. A pocket flashlight with a 2 5 V Welch-Allen bulb was aimed directly into one eye at 1 in.(2-2 cm) distance for 10 seconds. The other eye wascovered by the subject's or the examiner's hand,taking care that no pressure was applied to theglobe. When the flashlight was shut off, the subjectclosed the eyes and described what was seen. Theverbatim replies and the time were recorded in long-hand or on a tape recorder. After repeated trials on anumber of patients it was apparent that reports ofafter-images were reliable only for the first threeminutes after light exposure. If tests were continued,the persistence of the after-images, even slight and ofshort duration, would interfere with the test. There-fore, it was necessary to wait at least 10 minutes forresumption of the trials. The other eye was tested insimilar manner after a 10 minute interval. Manysubjects were tested repeatedly either on the same oron different days. Although the right eye was usuallytested first, on repeated trials the order of stimulationwas reversed.To employ the flight of colours, the examiner

should practise and determine the range of responsesin at least 10 or 20 normal subjects or patients with-out lesions of the visual system or cerebrum beforeevaluating the flight in a new patient. Although weperformed all testing after a period of dark adapta-tion, this is probably not essential. So long as theexaminer performs the stimulation to each eye insimilar manner, the criterion of asymmetry of re-sponse is usually reliable. The test should be repeated

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more than once in each eye. The response to thefirst light exposure may be misleading and shouldnot be considered as significant but only the secondand subsequent trials are reliable.

All patients also had a complete neurologicalhistory, examination, and laboratory tests whichoften included neuroradiological examinations. Thepatient's visual complaints included: 'blurring','double vision', 'I see the doughnut but not thehole', 'blackness to the left', 'the left side of theface looks large and twisted'. In addition to conven-tional perimetry, the visual fields were examined byconfrontation tests with large and small colouredtargets presented singly or by double simultaneousexposure. The visual fields were tested for dynamicchanges such as reduced visual adaptation time andextinction of one of a pair of targets. Ophthalmo-scopic examination included a description of theoptic disc, retina, and macula. Provocative testssuch as the 'hot bath test' were employed in selectedcases to determine whether there were subtle defectsin central vision. The ability to discriminate colourswas tested by American Optical Pseudoisochromaticplates and by the matching of wool skeins. (Silver-man, et al., 1961.)

After testing 100 normal subjects and 100 patientswith defective fields of vision for 'flight of colours',attempts were made at quantitative analysis tabula-ting such criteria as: (1) the number of colourchanges, (2) the duration and intensity of each colourphase as well as the rate of change, and (3) the totalduration of after-images in time. No single criterionadequately characterized the response nor was aquantitative combination of ratings of componentsof the response practical. Thus we categorized re-sponses qualitatively as 'good', 'fair', 'poor', or'absent'. A response was classified as 'good' whenit consisted of: (1) many colour changes includingred, orange, yellow, blue, purple or prominentcolours, (2) rapidly changing colours, (3) a durationof colour changes for at least two minutes. A 'fair'response consisted of fewer colour changes of lessprominent colours over a shorter time. A 'poor'response was one with only one or two colour changesof weak colours for less than 30 seconds. When nocoloured after-images except grey or pale yellowwere visualized, the response was 'absent'. Some-times a colourless light, either black, white, or grey,persisted for a short time or appeared and re-appeared. These categories were relative and based onour experience with the spectrum of responses sothat the classification of 'good' versus 'fair', forinstance, was often arbitrary. It was only aftertesting many patients and witnessing the spectrum ofpossible responses that subdivision of the spectrumwas attempted.

RESULTS

NORMAL POPULATION One hundred normal sub-jects of from 15 to 70 years of age were tested.Most of the younger subjects had a good flightof vivid colours. In those over 50 years of age theflight was 'fair', although some of them wererated as 'good'. The responses from illumina-tion of the left and right eyes were similar in eachof the subjects tested. In later ages some devia-tions from the normal may be found because ofchanges in ocular media or arterioscleroticchanges in the retinal or ophthalmic vessels orsenile degeneration in the macula.

CONGENITAL COLOUR BLINDNESS Seventeen sub-jects with congenital bilateral colour blindnessbut with normal fields of vision had absent flightof colours. After the flashlight beam exposurethere were changes of visual impressions butthey were not in conventional colour categories.They saw yellow or grey but not blue, green, orred colours in the after-images.

PATIENTS WITH LESIONS OF VISUAL SYSTEM Thecases studied in this group were subdivided intothose with lesions at different levels such as thatof the retina, optic nerve, optic tract, opticradiation, and occipital lobes. Only one or twocase descriptions are presented as examples,although we observed many cases in each of thesesubgroups.

1. Retina Twenty patients had lesions limitedto the retina with implication of the fovea. Theseincluded: (1) five patients with degenerativechanges of the macula, (2) two with chorio-retinitis, (3) eight with vascular occlusions, (4)three cases of detachment of the retina, and (5)two injuries or fluid collections of the retina. Inall of these patients the flight of colours duringvisual after-images was markedly reduced, 'poor'or 'absent' in the eye which had any type oflesion involving the macula and/or its immediatesurrounding. All of these patients had impairedcentral vision and relative scotomas.

Case I This 64 year old woman had blurred visionin the left eye from a retinal haemorrhage whichoccurred five years previously. At the time ofexamination there was a recurrence of blurred visionin the left eye. There was a sensation of a 'veil' over

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this eye 'first on the side and then toward thecentre'. The eye examination disclosed that theretina had a grey, blurred, and torn appearance.There was a collection of fluid in the superior por-tions, and the macula appeared discoloured. Thevisual acuity was reduced to 20/100 and there was acentral scotoma for colour and a defect for the per-ception of 3 mm red matches in the inferior nasaland to a slight extent the superior temporal quadrant.The visual fields in the right eye were normal. Theleft pupil responded to light sluggishly; the rightresponded briskly. The flight of colours in thevisual after-image elicited from the left eye consistedof only a few changes of 'dull murky' colours lastingonly 15 seconds; this was classified as a 'poor'response. The flight of colours elicited from the righteye was bright, changed every 10 to 15 seconds fromyellow, orange, red, purple, blue, green, etc., con-tinuing for 24 minutes.

In other conditions which may affect theretina in a diffuse manner but without involvingthe macula or leading to impairment of central orcolour vision such as papilloedema or hyper-tensive retinopathy, the flight of colours was'fair' to 'good'. In one patient with partialinvolvement of the macula and preservation of aportion of the central visual field the flightappeared in the intact functioning central field.In four cases of serous retinitis with macularoedema or macular degeneration and impairedcentral vision, there was impairment of flight ofcolours in the after-image.

2. Optic nerve In 22 patients with lesionslimited to the optic nerve, at the papilla or retro-bulbar region, central or caecocentral scotomaswere usually present and colour vision was im-paired. In these cases the flight of colours waseither 'fair', 'poor', or 'absent', depending uponthe degree of impairment of colour and formvision and the time of examination.

Case 2 This 23 year old man awakened with a painin the right eye and could not see in the centre of hisvisual field, although the periphery was clear. Hestated, 'I see the doughnut but not the hole'. Onexamination there was a central scotoma in OD fora 5° red target which extended temporally. Theacuity in the right eye was 20/70; 20/30 in the left.The fundi, optic discs, and pupillary reactions werenormal. When immersed in the hot bath with hisbody temperature raised to 38-9°C (102°F) thereappeared a large relative central scotoma in the right

eye. This was prominent and he could 'hardly see'except in the periphery of the field. At this time, hewas unable to perceive finger motion in the centralfield in front of the examiner's nose which served asthe fixation point. The left field of vision was normal.

In lesions of the optic nerve, the characteristicvisual field defect is a central or caecocentralscotoma. When the scotoma is relative or par-tial, a rise of the body temperature will make itabsolute. This and the absence of visual after-images and of flight of colours after light stimula-tion for 10 seconds are characteristic of an opticor retrobulbar optic neuritis.

Patients with optic atrophy and a densecentral scotoma at the time of testing had 'poor'to 'absent' flight of colours. In patients with ahistory of long-standing demyelinating diseaseand a past history of optic nerve involvement,even though the field of vision and fundi (opticdisc) might appear normal, the flight of colourswas often defective or 'fair' in the eye previouslyaffected. In such instances, the provocation by ahot bath test (Nelson and McDowell, 1959;Watson, 1959) often elicited a relative orabsolute central scotoma in the same eye.

Defective visual after-imagery with 'poor' or'absent' flight of colours in an eye was oftenassociated with the provocation of a centralscotoma upon hot bath testing. A 51 year oldpatient with a history of blurred vision in theright eye at the age of 44 years showed normaloptic nerves and normal flight of colours onadmission to the hospital. However, with the hotbath, central vision and flight of colours bWcameimpaired for a few hours.

3. Chiasm and/or the optic tract Fourteenpatients had chiasmal syndromes due to neo-plasm or aneurysm in the region of the sellaturcica and characterized by defects in bothtemporal fields of vision. In addition, thesepatients had absolute or relative central scotomasin one or both eyes, attributed to compression ofthe optic nerve. On specific questioning thesepatients had defective 'fair' or 'poor' flight ofcolours and after-images only in the eye with arelative scotoma and 'absent' in absolute centralscotoma.

Case 3 This 36 year old woman complained of

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FIG. 1. Case 3. Tangent screen examination with involvement of the opticchiasm and right optic nerve. There were bitemporal visual field defects andsevere restriction of the visual field in 0. D. which showed a central scotoma.Flashlight stimulation for 10 seconds in each eye revealed after-imagery with'poor' flight of colours in O.D. and 'fair' in O.S. Black area: no perceptionof hand motion. Small dots: n1o perception of 6 in. red. Large dots: tnoperception of 10° white.

seeing double while reading. On the following dayshe saw only shadow and light areas with the righteye. One month later, after drinking three glasses ofScotch whisky, there was a total loss of vision in theright eye for a few hours. When tested, she could seeonly large 6 in. (15 cm) red targets in the nasal fieldof the right eye, and there was a central scotoma inthis eye; there were mild defects in the temporal por-tion of the visual field of the left eye (Fig. 1). Thevisual acuity was 20/70 in the right eye. The rightoptic disc was pale. The left optic papilla was ofnormal appearance. On tests for visual after-imagerywith the flashlight method, the flight of colour was'poor' in the right and 'fair' in the left eye.The radiographs and angiography of the skull dis-

closed an intrasellar mass which had destroyed thegreater portion of the sella turcica, mostly on theright side.

In this patient with a lesion of the right side ofthe optic chiasm, there was a large centralscotoma and 'poor' flight of colours in the righteye. The left eye which had only a slight fielddefect with no involvement of the central fieldshowed a 'fair' flight. These findings suggesteda greater compression of the right optic nerve.

Patients with lesions in the region of thechiasm showed evidence of involvement ofrostral (optic nerve) and caudal structures suchas the optic tract. In some cases the features of

optic tract lesions preceded the chiasmal syn-drome, so that the two anatomical sites wereoften involved simultaneously. Later, during theprogression of the illness, optic nerves becomeimplicated. It was unusual to find a pure chiasmallesion. Most often there was additional opticnerve and less often optic tract implication. Wehad no cases of pure optic tract involvement.

Case 4 This 58 year old woman noted that hervision was not clear for a few months. Even after arefraction for new glasses she was unable to seeclearly. The right half of the image was clear but notthe left. In reading print she was unable to see thefirst letter of the words; some of the letters werequite clear and black while those to the left were'faded'. She claimed that the disturbance of visionwas getting progressively worse. With the eyesclosed, at times she noted colours moving from thecentre of the field to the left. When examined neuro-logically, there was a left homonymous hemiachro-matopsia for perception oflarge 6 in. (15 cm) colouredtargets, while visual perception of movement in thesehalf fields was preserved for 800 from the fixationpoint. There was a tendency for the hemiachromatop-sia to be more prominent in the left homonymoussuperior quadrants. No distinct scotoma could beplotted in the central or quadrant fields. However,when tested for visual after-images 12 days later, theflight of colours was absent in the right eye and

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FIG. 2. Casc 4. Talneiit screen examiinlationi ofpatient wit/i mass ivolviing theright optic tract, cliasm alid hoth optic itierr'es. Ther-e was a central scototina in0. D., anid a let ihoninnmnious inconigruenit he/imianiopic field c/eect. Thlerte wasalso anl irregular /o10/nonyious superior qliuaidranit (lefect ont the left. Tests fori.ivisal aftcr-inmigery wit/i flashlight stiiulfation revealedI ahsence of flig/it ofcolours ili 0. D. aild 'poor' inl O.S. Black area: iio perception of finger niotioni.x No perception of 3 red(. Large dots: per'ceptionI ofjfitiger' Inotioui huit niot 33white.

'good' in the left eye. Angiography and pneumo-

encephalography disclosed an avascular suprasellarmass in the midline and extending more to the rightside. Wlhen re-examined two weeks later, she haddistinct left homonymous scotomas implicating thesuperior and inferior quadrants near the fixationpoint and extending outward about 5 to 10'. Theywere more in the superior than in the inferior quad-rants. The flight of colours duL-ing visual after-imagery was still absent in the right and 'fair' in theleft eye. When reexamined five days later, she had a

left homonymous defect and a right superior quad-rant peripheral field defect; there was also a tem-poral field for colour in the left eye and now a

central scotoma in the right eye (Fig. 2). Thus therewas a combined lesion implicating the optic tract,optic chiasma, and right optic nerve. The flight ofcolours was absent in the right and became 'poor'in the left eye. She could not see the pseudoiso-chromatic plates with the right and made errors withthe left eye.

Radiotherapy to the sellar region was institutedand after six months of treatment there was a remark-able improvement in her vision; the gross fields ofvision were normal for perception of movement andlarge-sized colour targets. She made a few errors on

the pseudoisochromatic plates which were inconsis-

tent in the right eye. Six months thereafter, she stillhad no symptoms and she was able to see all thepseudoisochromatic plates. At this time the flight ofcolours was 'fair' in each eye.

What presented itself initially as a homoniymiioushemianopia, and thus was seemingly due to ageniculocalcarine lesion, was actually an optictract lesion. As the tumour enlarged, central, andthus colour, visiOln became impaired. Precedingthe impairment of colour visioIn was the im-paired or 'poor' flight of colours. The impair-ment of flight of colours in one eye was an earlysigin of involvement of central visioIn due tocompression of the optic nerve. Conversely, laterin the course, as the visual status improved, the'flight of colours' returned. Hence 'flight ofcolours' may be used as a sign of preservation ofcentral colour visioIn.

4. Lesions of parietal or temiiporal lobes affrctingoptic radliation Fifty-four patients with lesionsat different levels of the geniculocalcarine path-ways were examined. The homoniymous fielddefects varied in extent, degree of visual deficitincluding perception of motion, and colour.

Case 5 A 17 year old girl had headaches, doublevision, papilloedema, and a sixth nerve palsy inAugust 1966. The fields of vision, fundi, and pupil-lary reactions were intact. A left parietal ependy-moma was partially removed at surgery. In February1967, she had an episode of seizure activity with

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auditory and visual hallucinations. After gazing atcertain objects such as a foot or a face or smallletters on television, she continued to see a part ofthe object (a toe, an eye, a phrase) which projected ashigh as 6 feet (2 m) on the wall. This palinopticimage moved wherever the eyes moved. Initially, thethe fields of vision were intact but subsequentlyshowed a right homonymous hemiachromatopsia.The flight of colours was 'good' with each eye,despite the colour defects in the right homonymoushalf fields with implication of the half macLIla withsmall I mm green target.

All patients with lesions limited to the parietal ortemporal lobes or unilateral occipital lobe had'fair' to 'good' flights of colour. There were nodifferences if the patient happened to have amacular splitting homonymous hemianopsia orother types of homonymous field defects.Macular splitting homonymous hemiachroma-topsia did not alter the flight of colours. Patientswith diffuse processes affecting many regions ofthe brain with or without papilloedema usuallyhad 'fair' to 'good' flights.

5. Occipital lobes Patients with extensive lesionsaffecting one or both occipital lobes and densehomonymous hemianopsias but with preserva-tion of central vision had 'good' or 'fair' flightof colours. Some patients tended to localize theafter-image with changing colours to the intactfield and saw only half of the after-image. Thiswas rare, because most patients with Linilateral

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homonymous macular splittinlg hemianopsiassaw the colours changing diffusely throughoutboth sides of the field. In cases of bilateralposterior calcarine lesions with bilateral centralscotomas for colour the patient could not per-ceive small colour targets. Tests for light afterimagery revealed loss of flight of colour in thesepatients.

Case 6 An 18 year old boy had difficulty withvision to his left side for six months. On examinationthere was a dense left homonymous hemianopia formotion and colour. Macular vision was split forcolour. Despite this, tests for light after-imageryrevealed normal flight of colours in both eyes.Angiography demonstrated an infiltrating vascularmass in the right occipital lobe. At operation aglioblastoma was found and partially removed fromthe occipital lobe. Postoperatively, the fields ofvision were the same and the flight of colours were'good' in each eye.

When central visionl was spared in hemianopsiasdue to cerebral lesion, the flight of colour waspreserved even when the hemianopsia wasbilateral as illustrated by the next case.

Case 7 This 54 year old man had sudden onset ofbilateral hemianopsia in 1958. On initial examina-tion and repeat 10 years later, the fields of visionshowed double hemianopsia with preserved centralvision to 10° as plotted in Fig. 3. Colour vision wasnormal within 5' from the fixation point. As the

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FIG. 3. Case 7. Tangent screen examinlation ofpatient with double hemianopsiabut preserved central vision showing 'funnel vision'. Repeated tests for visualafter-imagery with flashlight in each eye disclosed the presenice of normal flightof colours. No perception of hand mnotion.

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target moved farther from the patient the degree ofthe field subtended was unchanged but the absolutediameter increased. In tests for visual after-imageryon flashlight stimulation, the flight of colours wasgood in each eye.

When visual perception of small colouredtargets was severely impaired in patients withdouble hemianopsias there was no flight ofcolours. This is illustrated in the next case.

Case 8 A 71 year old man, while under treatmentfor a 'heart attack', developed sudden inability tosee, preceded by a sensation of weakness in bothhands. Examination disclosed bilateral homonymoushemianopsia with preservation of central vision formotion but not for colour. The preserved homony-mous central fields revealed perception of motion 30to the right and 50 to the left of the fixation point.Stimulation with a flashlight exposed for 10 secondsin either eye evoked light after-images but there wasno flight of colours.

The critical defect which interfered with flight ofcolours in patients with double hemianopsias ofcerebral origin was loss of central vision, whetherfor perception of colour or of motion. Loss ofcolour vision in one half of central vision did notabolish flight of colour. The next case illustrateshow a lesion of both occipital lobes with loss ofcentral vision but bilaterally preserved peripheralcolour fields still caused a loss of the after-imageand flight of colours on strong light stimulation.

Case 9 This 32 year old marine, with shrapnelwounds of the posterior skull, had bilateral calcarinepole lesions which produced bilateral loss of visionwith preserved pupillary light reflexes. There wasgradual improvement in the peripheral portions ofthe fields of vision but central vision was permanentlylost. There were bilateral central scotomas (Benderand Furlow, 1945). In the fields surrounding thescotomas he perceived motion and some large colourtargets. There was no flight of colours in either eye.

DISCUSSION

The 'flight of colours' during visual after-imagery is a reflection of the function of theentire visual system as a unit. It also dependsupon the brain function necessary for perception.Thus, a light stimulus impinging upon theretina, which excites retinal elements, induces acycle of events transmitted through the optic

nerve, chiasm, tract, lateral geniculate body,optic radiation, and calcarine cortex to registeras a light. There is also an after-sensation or avisual after-image. This visual after-image can bedetected by different methods depending on thestrength of the light stimulus, as well as thepattern and size and colour of the stimulusobject (Bender and Kahn, 1949). With simpleflashlight stimulation for 10 seconds and closingthe eyes, the visual after-image appears as aseries of colours, usually yellow, blue, red, andcombinations. These colours probably representretinal cone elements which after excitationappear to react individually at different ratesand thus cause the visual sensation of flight ofcolours. When these elements act in unison thecolour is white. As to why these retinal elementsand photic products react at different periodsand in cycles lasting many seconds, we are notcompetent to discuss. It is essential that colourperception be within the repertoire of the indi-vidual. Thus, subjects with congenital 'colourblindness' had no colour in the after-image aswe conventionally consider it-that is, there wasno flight of colours other than sequences of greyor dull yellow. Similarly, destruction of macularvision on both sides of the midline, by a lesionanywhere along the visual projection systemeliminated the 'flight of colours'. For a given sizetarget, colours are perceived with greatestclarity in the central visual field. One millimetrered or green may be seen within 30° to 400,while large targets (5 cm) may be detected at 90°from the fixation point. In patients with lesionsof the occipital poles and bilateral impairment ofcentral vision with preserved perception ofmotion, colour vision may be severely impairedand there is no flight of colour. On the otherhand, in cases of double hemianopsias whichresulted in so-called 'funnel vision' with pre-served central vision for motion and intactcolour perception, there were vigorous flights ofcolours in the central after-image. When lesionsof the retina implicated the macula to the extentthat central vision was severely impaired, usefulcolour vision became lost and the flight ofcolours was absent. If the macula were onlypartially involved, the flight might still appear inthe uninvolved central region. In cases of hemi-anopsia or hemiachromatopsia, the visual after-image of a large pattern, such as an American

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flag or geometrical figure, in the affected field,will be missing, but the remaining normal visualfield, including central colour vision, and flightof colours are preserved.From the foregoing considerations, there is a

high correlation between the presence of centralcolour vision on both sides of the midline in oneeye and the presence of 'flight of colours'. Con-versely, when any portion of the visual pathwaymediating central vision is defective on bothsides of the midline, the flight is feeble or absent.This phenomenon may have value in patientswith suspected disease of the macula, opticnerve (retrobulbar or prechiasmal location), orbilateral occipital lobes. Even if there is noapparent defect in the fields of vision on standardtesting, there may be an asymmetry in the flightof colour response. This should arouse thesuspicion of early involvement of central visionin the affected eye. In conclusion, this simple bed-side test is a valuable method in detecting defectsin bilateral macular vision.

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