- Email: [email protected]
iPad colour vision apps for dyschromatopsia screening
Journal of Clinical Neuroscience 29 (2016) 92–94
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Clinical Study
iPad colour vision apps for dyschromatopsia screening Thomas Gordon Campbell a,d,⇑, Alexander Lehn b,c, Stefan Blum c, Caroline Airey b, Helen Brown b a
School of Medicine, University of Queensland, Herston, Brisbane, QLD 4072, Australia Department of Neurology, Princess Alexandra Hospital, Brisbane, QLD, Australia c Department of Neurology, Royal Brisbane and Women’s Hospital, Brisbane, QLD, Australia d Princess Alexandra Hospital, Brisbane, QLD, Australia b
a r t i c l e
i n f o
Article history: Received 17 May 2015 Accepted 28 October 2015
Keywords: Colour vision Dyschromatopsia iPad Neuro-ophthalmology Technology
a b s t r a c t Optic neuritis (ON) is a common and important cause of vision loss or vision disturbances in the community, particularly amongst the young, and it is often associated with a persistent dyschromatopsia. Traditionally screening for dyschromatopsia has been carried out using pseudo-isochromatic Ishihara plates. These colour plates were originally developed for testing of colour blindness, and indeed have only more recently been applied to ON. As the Ishihara plate books used for testing are expensive, unwieldy, and are not commonly available in many clinics or wards, many neurologists and ophthalmologists have taken to using untested and unstudied downloadable software packages on portable electronic devices for testing. This study compared the efficacy of printed and iPad (Apple, Cupertino, CA, USA) versions of the Ishihara plates in screening for dyschromatopsia in patients who were suspected of having ON. The main finding was that dyschromatopsia testing using a commercially available application on an iPad was comparable to using the current pragmatic clinical benchmark, the pseudo-isochromatic plates of Ishihara. These findings provide support for the increasingly common practice of screening for dyschromatopsia using the iPad. Ó 2015 Elsevier Ltd. All rights reserved.
1. Introduction Optic neuritis (ON) is a common and important cause of vision loss or vision disturbances in the community, particularly amongst the young. Classically ON presents with the clinical triad of eye pain, vision loss or distortion, and dyschromatopsia. It is an inflammatory, demyelinating condition of the optic nerve and is commonly associated with other demyelinating central nervous system diseases, such as multiple sclerosis or neuromyelitis optica [1–3]. Compared with other optic neuropathies, the prognosis of ON is generally good [3,4]. However, in a large proportion of patients dyschromatopsia persists indefinitely. As such it is important to maintain a high degree of clinical suspicion for dyschromatopsia in all patients in whom one suspects a history of ON or multiple sclerosis. Traditionally screening for dyschromatopsia has been carried out using pseudo-isochromatic Ishihara plates. These colour plates were originally developed for the testing of colour blindness, and have only more recently been applied to ON [5]. As the Ishihara plate books used for testing are expensive, unwieldy, and are not ⇑ Corresponding author. Tel.: +61 416 375 646. E-mail address: [email protected] (T.G. Campbell). http://dx.doi.org/10.1016/j.jocn.2015.10.042 0967-5868/Ó 2015 Elsevier Ltd. All rights reserved.
commonly available in many clinics or wards, many neurologists and ophthalmologists have taken to using downloadable software packages on portable electronic devices for testing. However, neither the computer screens nor the software packages used have been clinically validated or scientifically compared to traditional formats of colour vision testing using printed versions. This study compared the efficacy of printed and iPad (Apple, Cupertino, CA, USA) versions of the Ishihara plates in screening for dyschromatopsia in patients who were suspected of having ON. 2. Methods Patients were eligible for this study if they had been diagnosed with ON, multiple sclerosis, neuromyelitis optica, or were being investigated for possible optic neuropathy secondary to raised intracranial pressure. Exclusion criteria were primary diagnoses other than the above, or an inability to perform the task due to gross pathology or intellectual impairment. 2.1. Study oversight This research was carried out in accordance with the principles set out in the Australian National Health and Medical Research Council
T.G. Campbell et al. / Journal of Clinical Neuroscience 29 (2016) 92–94
93
guidelines for research involving humans. All participants provided informed consent before being enrolled. All authors take responsibility for the accuracy and completeness of the reported data. 2.2. Study protocol Testing was done in a clinical setting and was therefore pragmatic. Each eligible patient was asked to participate and, if informed consent was given, was randomly assigned to being tested on the iPad or Ishihara book first by the use of a random number generator. Data were collected by the testing clinician and entered using a standardised data collection form into a database. Testing was performed either in the clinic or at the bedside. Cross-over testing was performed as soon after initial testing as the clinical situation allowed (maximum delay was 5 minutes). Information collected included age, primary diagnosis, dates and number of previous episodes of ON, and best corrected visual acuity. Pseudo-isochromatic Ishihara plates were used [6,7]. Most (52 out of 70) of the eyes were tested on the first 21 plates of the 38 plate edition [6]. The remaining 18 eyes were tested on plates 2–17 of the 24 plate edition [7] as their current care was based on repeated testing using the 24 plate edition and it was believed to be inappropriate to change their established clinical treatment. The Colour Vision application or ‘‘app” (Color vision test HD – Medical eye Diagnostic chart and test, v1.0 [4+] by Dmitry Molokoedov) was purchased (AUD$1.99) and downloaded from the iTunes store (Apple) onto two new iPad 4. The brightness setting for each iPad was set to maximum. Testing was done in a clinical setting and was therefore pragmatic. Patients were asked to say each number they could see in the plate. If patients did not volunteer an answer after 10 seconds they were asked to guess what the number was. If they were unable to generate an answer after this the plate was recorded as a fail and the next plate was shown. Both minor and major errors were counted as a fail. All the testing rooms were lit with standard fluorescent bulbs. All the lights were turned on during testing and no effort was made to control for lighting variation. 2.3. Outcomes For the present analysis the primary outcome was the concordance between the percentage of plates correct on the Ishihara test as tested by book or by iPad. As the data was non-parametrically distributed the Spearman rank correlation coefficient (rho) was calculated and the statistical significance of the correlation was estimated from the critical value of rho. No subgroup analyses were planned or conducted. 3. Results There was wide inter-individual variation in the number of plates correctly answered between patients (range 4.8–100% correct). The number of plates answered correctly was not normally distributed. There was a strong right skew as many patients answered all plates correctly (Shapiro–Wilks normality test, W = 0.58, p < 0.00001). As such the statistical dependence between the number of plates answered correctly when tested using the Ishihara book and iPad was assessed using the non-parametric correlation test, Spearman’s rho. A very strong correlation was found between the number of plates answered correctly when tested using the pseudo-isochromatic Ishihara plates book and when tested using the Colour Vision iPad app (Spearman’s rho = 0.78, p < 0.00001; Fig. 1). Excluding the subset of patients tested on the 24 plate edition of Ishihara’s book did not change the results as a strong statistical dependence between the two scores gener-
Fig. 1. A comparison of printed and iPad iPad (Apple, Cupertino, CA, USA) versions of the Ishihara plates in dyschromatopsia screening.
ated by testing on the 38 plate edition was still found (Spearman’s rho = 0.76, p < 0.0001). Traditionally the minimum clinical significance of the Ishihara plates is considered to be five mistakes on the first 21 plates of the 38 plate edition and three mistakes on the first 15 plates of the 24 plate edition [6,7]. Only one of the 70 eyes tested had scores that differed by more than the minimum clinical significance. Interestingly this patient also had the lowest scores in the cohort. They identified only two of the 21 plates in the book and eight of the 21 plates on the iPad version. As such both tools identified this patient as having gross dyschromatopsia. 4. Discussion The key finding in this trial is that dyschromatopsia testing using a commercially available app on an iPad is comparable to using the current pragmatic clinical benchmark, the pseudoisochromatic plates of Ishihara. There was a very strong statistical dependence between the scores generated when testing using an iPad or the traditional Ishihara book. Dyschromatopsia screening is a crucial tool in the armoury of the neurologist and ophthalmologist. Traditionally screening has been carried out using pseudo-isochromatic Ishihara plates. However Ishihara plate books are expensive, unwieldy, and are not commonly available in many clinics or wards. Furthermore Ishihara plates should technically only be used under quite stringent lighting conditions. As such many younger doctors have taken to screening for dyschromatopsia with the one tool that all doctors can almost be guaranteed to have on them at all times; their iPhone or iPad. A multitude of apps exist which purport to ‘‘test colour vision”. However none has, to our knowledge, been scientifically validated in a peer-reviewed publication or compared with traditional screening methods in the clinical setting. This study aimed to rectify this deficiency. We have demonstrated that Colour Vision app is comparable to pseudo-isochromatic Ishihara plates in screening for dyschromatopsia in patients with known or suspected ON. This provides some evidence for the increasingly common practice of screening for dyschromatopsia using the ubiquitous and always available iPad. It also highlights the growing role and integration of personal tools and technology into medical practice. Conflicts of Interest/Disclosures H.B. received an educational grant from Bio-CSL. The other authors declare that they have no financial or other conflicts of interest in relation to this research and its publication.
94
T.G. Campbell et al. / Journal of Clinical Neuroscience 29 (2016) 92–94
References [1] Atkins EJ, Biousse V, Newman NJ. The natural history of optic neuritis. Rev Neurol Dis 2006;3:45–56. [2] Sørensen TL, Frederiksen JL, Brønnum-Hansen H, et al. Optic neuritis as onset manifestation of multiple sclerosis: a nationwide, long-term survey. Neurology 1999;53:473–8. [3] Optic Neuritis Study Group. Multiple sclerosis risk after optic neuritis: final optic neuritis treatment trial follow-up. Arch Neurol 2008;65:727–32.
[4] Beck RW, Smith CH, Gal RL, et al. Neurologic impairment 10 years after optic neuritis. Arch Neurol 2004;61:1386–9. [5] Regan D, Silver R, Murray TJ. Visual acuity and contrast sensitivity in multiple sclerosis–hidden visual loss: an auxiliary diagnostic test. Brain 1977;100:563–79. [6] Ishihara S. Ishihara’s tests for colour-deficiency: 38 plate edition. Japan: Kanehara & Co. LTD; 1996. [7] Ishihara S. Ishihara’s Test for colour-deficiency: 24 plates edition. Japan: Kanehara & Co. LTD; 1996.
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Clinical Study
iPad colour vision apps for dyschromatopsia screening Thomas Gordon Campbell a,d,⇑, Alexander Lehn b,c, Stefan Blum c, Caroline Airey b, Helen Brown b a
School of Medicine, University of Queensland, Herston, Brisbane, QLD 4072, Australia Department of Neurology, Princess Alexandra Hospital, Brisbane, QLD, Australia c Department of Neurology, Royal Brisbane and Women’s Hospital, Brisbane, QLD, Australia d Princess Alexandra Hospital, Brisbane, QLD, Australia b
a r t i c l e
i n f o
Article history: Received 17 May 2015 Accepted 28 October 2015
Keywords: Colour vision Dyschromatopsia iPad Neuro-ophthalmology Technology
a b s t r a c t Optic neuritis (ON) is a common and important cause of vision loss or vision disturbances in the community, particularly amongst the young, and it is often associated with a persistent dyschromatopsia. Traditionally screening for dyschromatopsia has been carried out using pseudo-isochromatic Ishihara plates. These colour plates were originally developed for testing of colour blindness, and indeed have only more recently been applied to ON. As the Ishihara plate books used for testing are expensive, unwieldy, and are not commonly available in many clinics or wards, many neurologists and ophthalmologists have taken to using untested and unstudied downloadable software packages on portable electronic devices for testing. This study compared the efficacy of printed and iPad (Apple, Cupertino, CA, USA) versions of the Ishihara plates in screening for dyschromatopsia in patients who were suspected of having ON. The main finding was that dyschromatopsia testing using a commercially available application on an iPad was comparable to using the current pragmatic clinical benchmark, the pseudo-isochromatic plates of Ishihara. These findings provide support for the increasingly common practice of screening for dyschromatopsia using the iPad. Ó 2015 Elsevier Ltd. All rights reserved.
1. Introduction Optic neuritis (ON) is a common and important cause of vision loss or vision disturbances in the community, particularly amongst the young. Classically ON presents with the clinical triad of eye pain, vision loss or distortion, and dyschromatopsia. It is an inflammatory, demyelinating condition of the optic nerve and is commonly associated with other demyelinating central nervous system diseases, such as multiple sclerosis or neuromyelitis optica [1–3]. Compared with other optic neuropathies, the prognosis of ON is generally good [3,4]. However, in a large proportion of patients dyschromatopsia persists indefinitely. As such it is important to maintain a high degree of clinical suspicion for dyschromatopsia in all patients in whom one suspects a history of ON or multiple sclerosis. Traditionally screening for dyschromatopsia has been carried out using pseudo-isochromatic Ishihara plates. These colour plates were originally developed for the testing of colour blindness, and have only more recently been applied to ON [5]. As the Ishihara plate books used for testing are expensive, unwieldy, and are not ⇑ Corresponding author. Tel.: +61 416 375 646. E-mail address: [email protected] (T.G. Campbell). http://dx.doi.org/10.1016/j.jocn.2015.10.042 0967-5868/Ó 2015 Elsevier Ltd. All rights reserved.
commonly available in many clinics or wards, many neurologists and ophthalmologists have taken to using downloadable software packages on portable electronic devices for testing. However, neither the computer screens nor the software packages used have been clinically validated or scientifically compared to traditional formats of colour vision testing using printed versions. This study compared the efficacy of printed and iPad (Apple, Cupertino, CA, USA) versions of the Ishihara plates in screening for dyschromatopsia in patients who were suspected of having ON. 2. Methods Patients were eligible for this study if they had been diagnosed with ON, multiple sclerosis, neuromyelitis optica, or were being investigated for possible optic neuropathy secondary to raised intracranial pressure. Exclusion criteria were primary diagnoses other than the above, or an inability to perform the task due to gross pathology or intellectual impairment. 2.1. Study oversight This research was carried out in accordance with the principles set out in the Australian National Health and Medical Research Council
T.G. Campbell et al. / Journal of Clinical Neuroscience 29 (2016) 92–94
93
guidelines for research involving humans. All participants provided informed consent before being enrolled. All authors take responsibility for the accuracy and completeness of the reported data. 2.2. Study protocol Testing was done in a clinical setting and was therefore pragmatic. Each eligible patient was asked to participate and, if informed consent was given, was randomly assigned to being tested on the iPad or Ishihara book first by the use of a random number generator. Data were collected by the testing clinician and entered using a standardised data collection form into a database. Testing was performed either in the clinic or at the bedside. Cross-over testing was performed as soon after initial testing as the clinical situation allowed (maximum delay was 5 minutes). Information collected included age, primary diagnosis, dates and number of previous episodes of ON, and best corrected visual acuity. Pseudo-isochromatic Ishihara plates were used [6,7]. Most (52 out of 70) of the eyes were tested on the first 21 plates of the 38 plate edition [6]. The remaining 18 eyes were tested on plates 2–17 of the 24 plate edition [7] as their current care was based on repeated testing using the 24 plate edition and it was believed to be inappropriate to change their established clinical treatment. The Colour Vision application or ‘‘app” (Color vision test HD – Medical eye Diagnostic chart and test, v1.0 [4+] by Dmitry Molokoedov) was purchased (AUD$1.99) and downloaded from the iTunes store (Apple) onto two new iPad 4. The brightness setting for each iPad was set to maximum. Testing was done in a clinical setting and was therefore pragmatic. Patients were asked to say each number they could see in the plate. If patients did not volunteer an answer after 10 seconds they were asked to guess what the number was. If they were unable to generate an answer after this the plate was recorded as a fail and the next plate was shown. Both minor and major errors were counted as a fail. All the testing rooms were lit with standard fluorescent bulbs. All the lights were turned on during testing and no effort was made to control for lighting variation. 2.3. Outcomes For the present analysis the primary outcome was the concordance between the percentage of plates correct on the Ishihara test as tested by book or by iPad. As the data was non-parametrically distributed the Spearman rank correlation coefficient (rho) was calculated and the statistical significance of the correlation was estimated from the critical value of rho. No subgroup analyses were planned or conducted. 3. Results There was wide inter-individual variation in the number of plates correctly answered between patients (range 4.8–100% correct). The number of plates answered correctly was not normally distributed. There was a strong right skew as many patients answered all plates correctly (Shapiro–Wilks normality test, W = 0.58, p < 0.00001). As such the statistical dependence between the number of plates answered correctly when tested using the Ishihara book and iPad was assessed using the non-parametric correlation test, Spearman’s rho. A very strong correlation was found between the number of plates answered correctly when tested using the pseudo-isochromatic Ishihara plates book and when tested using the Colour Vision iPad app (Spearman’s rho = 0.78, p < 0.00001; Fig. 1). Excluding the subset of patients tested on the 24 plate edition of Ishihara’s book did not change the results as a strong statistical dependence between the two scores gener-
Fig. 1. A comparison of printed and iPad iPad (Apple, Cupertino, CA, USA) versions of the Ishihara plates in dyschromatopsia screening.
ated by testing on the 38 plate edition was still found (Spearman’s rho = 0.76, p < 0.0001). Traditionally the minimum clinical significance of the Ishihara plates is considered to be five mistakes on the first 21 plates of the 38 plate edition and three mistakes on the first 15 plates of the 24 plate edition [6,7]. Only one of the 70 eyes tested had scores that differed by more than the minimum clinical significance. Interestingly this patient also had the lowest scores in the cohort. They identified only two of the 21 plates in the book and eight of the 21 plates on the iPad version. As such both tools identified this patient as having gross dyschromatopsia. 4. Discussion The key finding in this trial is that dyschromatopsia testing using a commercially available app on an iPad is comparable to using the current pragmatic clinical benchmark, the pseudoisochromatic plates of Ishihara. There was a very strong statistical dependence between the scores generated when testing using an iPad or the traditional Ishihara book. Dyschromatopsia screening is a crucial tool in the armoury of the neurologist and ophthalmologist. Traditionally screening has been carried out using pseudo-isochromatic Ishihara plates. However Ishihara plate books are expensive, unwieldy, and are not commonly available in many clinics or wards. Furthermore Ishihara plates should technically only be used under quite stringent lighting conditions. As such many younger doctors have taken to screening for dyschromatopsia with the one tool that all doctors can almost be guaranteed to have on them at all times; their iPhone or iPad. A multitude of apps exist which purport to ‘‘test colour vision”. However none has, to our knowledge, been scientifically validated in a peer-reviewed publication or compared with traditional screening methods in the clinical setting. This study aimed to rectify this deficiency. We have demonstrated that Colour Vision app is comparable to pseudo-isochromatic Ishihara plates in screening for dyschromatopsia in patients with known or suspected ON. This provides some evidence for the increasingly common practice of screening for dyschromatopsia using the ubiquitous and always available iPad. It also highlights the growing role and integration of personal tools and technology into medical practice. Conflicts of Interest/Disclosures H.B. received an educational grant from Bio-CSL. The other authors declare that they have no financial or other conflicts of interest in relation to this research and its publication.
94
T.G. Campbell et al. / Journal of Clinical Neuroscience 29 (2016) 92–94
References [1] Atkins EJ, Biousse V, Newman NJ. The natural history of optic neuritis. Rev Neurol Dis 2006;3:45–56. [2] Sørensen TL, Frederiksen JL, Brønnum-Hansen H, et al. Optic neuritis as onset manifestation of multiple sclerosis: a nationwide, long-term survey. Neurology 1999;53:473–8. [3] Optic Neuritis Study Group. Multiple sclerosis risk after optic neuritis: final optic neuritis treatment trial follow-up. Arch Neurol 2008;65:727–32.
[4] Beck RW, Smith CH, Gal RL, et al. Neurologic impairment 10 years after optic neuritis. Arch Neurol 2004;61:1386–9. [5] Regan D, Silver R, Murray TJ. Visual acuity and contrast sensitivity in multiple sclerosis–hidden visual loss: an auxiliary diagnostic test. Brain 1977;100:563–79. [6] Ishihara S. Ishihara’s tests for colour-deficiency: 38 plate edition. Japan: Kanehara & Co. LTD; 1996. [7] Ishihara S. Ishihara’s Test for colour-deficiency: 24 plates edition. Japan: Kanehara & Co. LTD; 1996.