ACTA O P H T H A L M O L O G I C A VOL. 5 4 1 9 7 6
Departments of Experimental Ophthalmology (Head: C . E. T. Krakazi) nnd Neiiro-Ophtlialniology (Head: H . Bynkc), University Hospital. Lund, Sweden
A PORTABLE HEMIANOPSIA TESTER BY
H. BYNKE and A. HEIJL
A pocket-size static perimeter provided with four test lights, one for each quadrant of the visual field, has been constructed and applied to 190 visual fields in 97 patients. T h e main advantage of the instrument is its ability to disclose hemianopic defects in bedridden a n d certain sick patients unable to co-operate with other methods, including the confrontation test. This was performed in 12 fields in 7 patients.
Key words: perimetric instrument - perimetry - multiple stimulus perimetry - bedside examination - visual field - hemianopsia - quadrantanopsia.
Pre-requisites for a successful1 examination of the visual field are that the subject understands the procedure and is able to keep his eye fixed and his attention concentrated for the duration of the examination. In conventional perimetry he must also be seated. Patients who are mentally disturbed as a result of intracranial disease and young children may lack one or more of these requirements. I n such cases the confrontation test may be the only feasible method of visual field examination. Then, the static stimulation with two hands placed symmetrically in the field is much superior to the kinetic confrontation test with one hand. Received January 2, 1976.
A Portable Hentianopsia Tester
The former test may disclose even relative hemianopsias, but is too crude and simple to permit such variations of the procedure that may be necessary to confirm the existence of a field defect. The hands may be replaced by other stimuli, e. g. red targets in order to test the colour saturation. This facilitates the detection of relative hemianopsias but also demands more cooperation from the subjects. Many instruments have been constructed especially for bedridden patients, but there are also other instruments suitable for bedside examination (Schweigger 1889; Holth 1914; Harrington & Flocks 1954; Krimsky 1965; Ben-Tovim 1965, 1967, 1972; Cohen 1971, 1974; Rubey 1972). However, none of them has been constructed specifically to suit less cooperative patients, and the authors have not published any results relating to such cases. One advantage of certain static, multiple stimulus instruments, e. g. Friedmann’s Visual Field Analyser (Friedmann 1966) is the short exposure time of the test lights. The subject’s attention is occupied only momentarily, and the exposure time is too short to permit any change of fixation. Thus, Friedmann’s Analyser has been found more suited than the kinetic methods for examination of young children (Bynke & Nordenfelt 1974). However, it cannot be used for bedside examinations.
Fig. 1. The instrument. S: Stimuli, F: Fixation point, P: Step-wheel for regulation ol position and number of stimuli, D : Display, B: Button for exposure of stimuli, 1: Step-wheel for regulation of intensity of stimuli.
H . Bynke and .4. H e i j l
Modern electronics makes it possible to solve certain problems arising in the construction of small, light-weight instruments suitable for bedside examinations. Th e purpose of this paper is to describe an instrument combining the advantages ,of the simple confrontation test and the multiple stimulus instrument mentioned and to demonstrate its suitability for bedridden and less cooperative patients.
The Instrument and Its Use T h e instrument is a portable hemianopsia tester (PHT) measuring 15 x 21 x 2.5 cm and weighing 350 g (Fig. 1). A central, red fixation light and four yellow test lights, one for each quadrant of the field, have been mounted on a black plate. Experience of light-emitting diodes (LEDs) as light sources in perimetry (Heijl & Krakau 1975a,b) led us to choose them as light sources both for the fixation light and the test stimuli. LEDs are stable, respond to square-wave currents with square-wave light and give a light intensity directly proportional to the current flowing through them. When placed 30 cm from the eye being examined, the eccentricity of the test lights is 15 degrees. One or two test lights, or all four, may be exposed simultaneously. The number and the position of the exposed stimuli are regulated by rotating a 10-step-wheel and are indicated by a LED display. The intensity of the test lights is chosen by means of another 10-step-wheel. T he ratio between adjacent intensity levels is VF. Th e test lights are exposed for 0.2 seconds by pressing a button. This exposure time has been chosen because it approximately equals the latency time of ocular movements (Westheimer 1954). It is too short to allow the patient to direct his eye at the stimulus. T he wheels, the display and the button are situated in a small panel at right angles to the plate with the lights. The instrument is held by the examiner with the plate perpendicular to the visual axis of the eye examined. A moderate tilting of the instrument does not noticeably reduce the visibility of the lights, which are situated on the plane of the plate. By exposing high intensity levels, the instrument may be used for bedside examinations in fairly well illuminated wards. It is convenient to start the examination by exposing all four test lights at maximal intensity. This is then reduced stepwise until fewer than four lights are recognized, and so on, until no light is seen. I n deep visual field defects, the number of intensity steps between the maximal and minimal number of test lights recognized is large. In shallow defects and normal fields this number is small. When an appropriate intensity level has been arrived at, the examina176
A Portable Heminnopsia Tester
tion proceeds at this intensity by changing the number and positions of the test lights. I n most cases it is enough to use 2-light-combinati~ons.However, in cases of dysphasia, dyscalculia or lethargy, the procedure may be further simplified by using the four 1 -light-positions at various intensity levels and asking the patient to point at the lights recognized. In any event, the whole procedure takes only a few minutes.
Material The material consisted of 190 visual fields in 97 patients, 48 males and 49 females aged between 5 and 81 years. The majority of the patients suffered from intracranial diseases such as tumours, cerebrovascular lesions and degenerations. In some cases, intracranial disease was suspected but could not be confirmed. At the time of the present investigation, between February and October 1975, or previously, they were being treated as in-patients in the neurological, neurosurgical or other departments of the University Hospital in Lund. The material has been divided into four groups: GiOUp l a
50 fields in 27 patients were normal according to kinetic Goldmann perimetry
and tangent screen examination. Group 1 b
In 54 fields in 31 patients there were relative hemianopsias or quadrantanopsias. These were homonymous in 12 cases, bitemporal in 1 1 and uniocular in 8. They were confirmed by Goldmann perimetry and/or tangent screen examination. Th e size of these defects varied considerably. The majority were of moderate size, but some of the bitemporal hemianopsias were small, i. e. only demonstrable within 15 degrees of the fixation point. Group 1 c
In 33 fields in 19 patients there was either a total or subtotal hemianopsia or a quadrantanopsia. These defects were homonymous in 13 cases, bitemporal in one and uniocular in 5 . They were confirmed by Goldmann perimetry. tangent screen examination, confrontation test, or by two of these methods. 177 Actn ophthal. 54, 2
H . Bynke and A . Heijl Group 2
I 27 patients there was a more or less pronounced instability of fixation and a decreased understanding of the procedure because of lethargy, senile dementia or young age. Seven patients were bedridden and six were children aged between 5 and 9 years. These 27 patients did not cooperate with Goldmann perimetry or tangent screen examination, and 14 of them could not even co-operate with the confrontation test. Among the 13 patients who cooperated more or less satisfactorily in this test, a homonymous hemianopsia was disclosed in one single case. In 12 cases, the confrontation test was interpreted as negative. These patients, like the majority of the other cases in this study, were thoroughly examined by neuro-radiological and other methods. In the tumour cases, the diagnoses were verified at the neurosurgical intervention.
Methods Control methods of examination were the quantitative, kinetic Goldmann perimetry and the tangent screen examination. With perimetry at least two, and, in the majority of the cases with defective fields, a t least three white objects were used. Special attention was devoted to exploring the central field. With tangent screen examination, white targets of 10, 2 and 1 mm were used at a distance of 2 m. In 13 less cooperative patients the only control method available was the confrontation test. This was performed with single as well as double simultaneous hands. In some cases, two simultaneous red targets were also utilized. The P H T was used in the manner already described. This examination was made on the same occasion as the control methods. In 33 patients, the examination was started with the P H T and in 50 with the control methods. In 14 patients the P H T was the only available method. The Goldmann perimetry was carried out by the authors or by trained assistants, whose results were in several cases checked by the authors. The other examinations were performed by the authors.
Results The results have been summarized in Tables I, I1 and 111. They do not appear to be influenced by whether the examination started with the control methods or with the PHT. 178
A Portable Hernianopsia Tester Table I. The findings of the portable hemianopsia tester in 137 visual fields in 70 patients, who were able to co-operate with Goldmann perimetry and tangent screen examination. Portable hemianopsia tester (Nos. of fields) Results of Goldmann perimetry and tangent screen examination ”
Group 1 b. Relative hemianopsias and quadrantanopsias 54 fields in 31 patients
Group 1 c. Total or subtotal hemianopsias and quadrantanopsias 33 fields in 19 patients
Group 1 a. Normal visual fields 50 fields in 27 patients
Group 1 a
In 47 out of the 50 normal fields, no defect could be demonstrated by the PHT. One patient with dementia missed some test lights in both fields, and another one with a unilateral nasal cataract occasionally missed test lights in the temporal field of that eye. Since the answers were varying and inconsistent, these 3 fields have been designated as questionably positive (Table I). With all four test lights exposed, the intensity range between the maximal and minimal number of recognized test lights was 1-2 steps in this group. Group 1 b
39 out of the 54 relative hemianopsias or quadrantanopsias were demonstrated by the PHT. There was full concordance between the P H T and the control methods as regards the position of the defects in these fields. In 8 fields (5 patients) defects were also found by the PHT, but since their position could not be established they have been designated as questionably positive. I n 7 fields (4 patients) the defects were missed by the P H T (Table I). In one patient the defects missed were of moderate size, and in the others they were 179 12”
I € . Bynke nird A . Heijl
small, i. e. demonstrable only inside 15-20 degrees from the fixation point. The intensity range between the maximal and minimal number of recognized test lights was 2-7 steps in this group. Group 1 c
In all the 33 fields with either total or subtotal hemianopsia or quadrantanopsia the defects were demonstrated by the PHT and their position corresponded to that found by the control methods (Table I). The intensity range was 6-8 steps in this group. Group 2
Among the 27 patients who were unable to co-operate with perimetry and tangent screen examination, the PHT disclosed defects in 7 (12 fields) (Tables I1 and 111). These defects were homonymous in 5 cases and uniocular in 2. Five of the 7 patients did not even cooperate with the confrontation test. In
Table 11. The findings of the portable hemianopsia tester in 53 visual fields in 27 patients unable to co-operate with Goldmann perimetry and tangent screen examination. Portable hemianopsia tester (Nos. of fields) Results of confrontation test
Positive (homonymous hemianopsia) 2 fields in 1 patient
Negative 24 fields in 12 patients Not possible 27 fields in 14 patients
* On the basis of clinical symptoms and signs and neuro-radiological findings, there ++
was no reason to assume any visual field defect in these cases. Three of these 10 patients had hemi-symptoms and positive neuro-radiological findings which might indicate the existence of a homonymous hemianopsia.
A Porloblc Hcminnopsin I'cslcr Triblc I l l . Seven patients in whom the portable hemianopsia tester (PHT) revealed visual field defects, not demonstrable by other methods. Initials, Sex, Age (years)
AS, f, 9
Laceration rt. parieto-occipital lobe
Lethargy Lt. hemiparesis Asymmetric OKN Choked discs
Lt. homonymous hemianopsia
KP, m, 7 1
Cerebrovascular lesion Diab. mellitiis
Acquired dementia Not possible Epilepsy Lt. hemiparesis Asymmetric OKN Diab. retinopathy
Lt. homonymous hemianopsia
BJ, m, 74
Cerebr. atrophy Gerstmann's syndr. Negative Apraxia Memory disturb. Reduced CBF esp. It. cerebral hemisphere
H N , m, 49
Malign. glioma rt. temporal lobe
HL, m, 66
Malignant pituit. adenoma
Frontal lobe syndr. Not possible Lt. eye blind Bilateral optic atrophy
Confusion Lt. hemiparesis Rt. hemiataxia
Lt. homonymous hemianopsia
Lt. homonymous hemianopsia and rt. homonymous superior quadrantanopsia
Cerebrovascular lesion Arterial hypertension Rt. optic infarction
Lethargy Rt. hemiparesis Dysphasia Rt. optic disc pale lower half
Superior altitudinal defects rt. field Normal It. field
NT, m, 73
Rt. homonymous inferior quadrantanopsia
Lt. homonymous hemianopsia Temporal hemianopsia rt. field
If. Bynkc and A . Heijl one patient (BJ) this test was interpreted as negative, and in another one (VJ) it revealed a left total homonymous hemianopsia. In the cases of homonymous hemianopsia the lesions in the opposite cerebral hemispheres were demonstrated by neuro-radiology and/or were known to exist because of other focal signs. In VJ, in whom there were severe traumatic cerebral lesions, the P H T added the information that there were also homonymous defects in the right superior quadrants. The uniocular defects were due to a malignant pituitary adenoma in a patient (HL) whose other eye was blind, and a n optic nerve infarction in a patient (NT) whose other field was normal. Thus, in all the positive cases, the visual field defects were obviously consistent with other clinical findings (Table 111). Two patients (AS and H L ) were examined by both of us independently and with identical results. One patient(HN) was reexamined later on, when he cooperated with perimetry. His hemianopsia was verified on this occasion. In 2 patients (4 fields) questionably positive defects were found by the PHT. T h e other 19 cases (37 fields) were negative according to this method. Nine of them did not cooperate with the confrontation test. O n the basis of clinical symptoms and signs and neuro-radiological findings there was no reason to assume any visual field defects in the questionable positives and in the majority of negatives (Table 11).
Discussion The P H T disclosed 81, or if the questionable positives were excluded, 73 out of the 88 hemianopic defects which were demonstrated by the control methods. In other words, the false negative fields amounted to 8 O/O and 1 7 O/O, respectively. Most of the false negative defects were small. Some of them were demonstrable only within 15 degrees of the fixation point. At a working distance of 30 cm these defects could not be expected to be found by the PHT. Another problem in shallow defects was to find the appropriate low intensity level for the examination. This was because the intensity steps between the maximal and minimal number of lights recognized, with all four test lights being exposed, was about equal in shallow defects and in normal fields. This problem, which is difficult to solve, also contributed to the false positive findings, and exists in all static, multiple stimulus methods (Greve 1973). It would evidently have been possible to reduce the number of false 182
A Portable Hemianopsin Tester
negatives by increasing the number of test lights and by testing each field at various working distances. We have intentionally refrained from doing this, since the primary purpose was to produce a handy instrument able to disclose large and moderate-sized defects in less cooperative and bedridden patients. The fact that the P H T revealed defects in 5 patients unable to cooperate with the confrontation test a n d in 2 patients whose defects could not be demonstrated by this test proves that the primary purpose has been achieved. It is easy to overrate a new instrument for visual field examination, if the full capacity of the control methods is not utilized. W e are aware of this error, and have discussed it elsewhere (Bynke & Nordenfelt 1974). However, after having used the PHT in clinical practice, we are convinced of its value in testing less cooperative and bedridden patients. At least it permits a n exploration of the paracentral visual field, which cannot be performed by the simple confrontation test. Finally, it should be mentioned that the PHT may be a valuable supplement to the confrontation test in the hands of non-ophthalmologists.
Acknowledgment The electronics of this instrument was built by Mr. R. Uhman, research engineer.
References Ben-Tovim N. (1965) New perimetric instrument. T h e Campiscope. Amer. /. Oplzthal. 59, 503-504. Ben-Tovim N. (1967) The Scotopter. Amer. /. Ophthal. 64, 780-785. Ben-Tovim N. (1972) T h e Campiscope. A new model. Amer. /. Ophthal. 74, 346-347. Bynke H . & Nordenfelt L. (1974) T h e Friedmann Visual Field Analyser tested on neuro-ophthalmological cases. Acta ophthal. (Kbh.) 52, 861-871. Cohen S. W. (1971) A pocket perimeter. Arch. Ophthal. (Chicago) 86, 186188. Cohen S. W. (1974) A "pocket" campimeter. Ann. Ophtha2. 6 , 765-768. Friedmann A. I. (1966) Serial analysis of changes in visual field defects employing a new instrument, to determine the activity of diseases involving the visual pathways. Ophthalmologica 152, 1-12. Greve E. L. (1973) Single and multiple stimulus static perimetry in glaucoma; the two phases of perimetry. Docum. ophthal. 36, pp. 1GO-161. Harrington D. 0. & Flocks M. (1954) Visual field examination by a new tachystoscopic multiple-pattern method. Amrr. /. Ophthal. 37, 7 19-723.
H. Bynkc utid A . Hcijl Heijl A. & Krakau C. E. T. (1975a) A n automatic static perimeter, design and pilot study. Actn ophthal. (Kbh.) 53, 293-310. Heijl A. & Krakau C. E. T. (1975b) An automatic perimeter for glaucoma visual field screening and control. Construction and clinical cases. Grnrfcs Arch. Ophthal. 197, 13-23. Holth S. (1914) Das Kordenperimeter. Ein billiger Tascheninstrument fur gute Gesichtsfelduntersuchungen. Klin. Mbl. AugcJnhcilk.5.3. 197-201. Krimsky E. (1965) An eyecup perimeter. Trans. Amer. Acad. Ophthal. Otolaryng. 69, 4 74-4 75. Rubey F. (1972) Beitrag z u r Perimetrie am Krankenbett. K l i n . Mbl. Augcnheilk. IGO, 223-226. Schweigger C. (1889) Ein handliches Perimeter. Arch. Augcnheilk. 19, 469-470. Westheimer G. (1954) Eye movement responses to a horizontally moving visual stimulus. Arch. Ophthnl. (Cliicrigo) 52, 932-941.
Authors’ addresses: Hans Bynke, M. D., University Eye Clinic, S-221 85 Lund, Sweden. Anders Heijl, M. D., Department of Experimental Ophthalmology, University Eye Clinic, S-221 85 Lund, Sweden.