- Email: [email protected]
Grading morphs
Part I Examination and Grading
3 C H A P T E R
Grading morphs
Although grading performance can be enhanced by interpolation to the nearest 0.1 grade unit,1 most practitioners find the process of mental interpolation between two discrete grading steps to be quite difficult, notwithstanding the fact that this task becomes easier with practice. One way of partially overcoming this difficulty is to re-engineer the grading scales into a continuous movie sequence, progress through which can be controlled by the clinician attempting to decide upon a grade. Modern computer software technology is available to undertake such tasks; the process of merging discrete images into a continuous movie sequence is known as ‘morphing’. The results of morphing will be familiar to many readers because this technique is used extensively in the visual arts to change the appearance of an object or person into another – for example, changing the face of one person seamlessly into that of another. Morphing is a technique that allows accurate interpolation of numerous progressively changing images between a ‘start’ and ‘end’ image, which are calculated pixel by pixel. When these images are presented one after the other in rapid succession, a movie or animation results, which allows one to observe the ‘start’ image being transformed into the ‘end’ image. The greater the number of interpolated images, the smoother will be the movie sequence. If the ‘start’ and ‘end’ images are not identical, the morphing technician can use software to link common elements in these images, which are identified manually. The only limitation to the number of interpolated images is the amount of computer memory available, because a high-resolution image in many colours can be memory-intensive.
Efron Grading Morphs Morphing animation sequences have been developed for each of the 16 complications depicted in Appendix A and have been incorporated into a computer program called ‘Efron Grading Morphs’. This can be downloaded from the expertconsult website www.expertconsult.com using the code in the front of this book. The ‘Efron Grading Morphs’ and ‘The Efron Grading Tutor’ (described below) will operate on IBM compatible © 2012 Elsevier Ltd
PC platforms (Windows 7, Vista, XP or higher) and Apple Macintosh platforms (Mac OS X or higher). The software may also operate on other computer configurations, although full testing has only been performed on the above configurations. The operation of the ‘Efron Grading Morphs’ program is described below.
Program operation When the ‘Efron Grading Morphs’ program is opened a title page appears. Click on ‘Skip’. A second window appears, from which you can choose any one of the 16 available grading morphs shown in the vertical scrolling menu along the left of the window. The choice of available morphs can be viewed by either (a) clicking on the scroll handle and dragging it up or down; or (b) clicking on the up or down arrows, until the desired complication can be seen. Once located, click on the desired complication. It will become highlighted in a yellow box, and the corresponding grading morph will be displayed in the centre of the window. The slide bar immediately beneath the grading morph can be adjusted by clicking and holding the small white rectangular slide bar control handle and moving it in the appropriate direction. When the slide bar control handle is moved to the right, the grading morph advances and the level of severity increases. Moving the slide bar control handle to the left will reverse the grading morph to a lower level of severity. The slide bar control handle can be moved back and forth in this way until the desired level of severity is achieved. The numeric grading indicating the level of severity of the condition being displayed is indicated in the right hand box as the grading morph is adjusted. This numeric grading is indicated to the nearest 0.1 grading scale unit, within the range from 0.0 (normal) to 4.0 (severe). The slide bar control handle can be released, re-engaged and moved as many times as required, before selecting an alternative grading morph, or quitting. The Efron Grading Morphs program window is shown in Figure 3.1. In this example, papillary conjunctivitis has been selected; this is highlighted by a yellow box in the
Grading morphs
Figure 3.1 Efron Grading Morphs program window. In this example, the papillary conjunctivitis morph is active.
vertical scrolling menu on the left hand side of the window. The slide bar control handle has been advanced to grade 2.7; this numeric grade is also displayed in the right hand panel. For masking purposes, the numeric grading can be ‘hidden’ by clicking on the ‘Hide Grade’ button beneath the numeric grade window. The numeric grading can then be revealed again by clicking on the same button, which is now called ‘Show Grade’. The operator can toggle between ‘Show Grade’ and ‘Hide Grade’ modes as often as required. To view a movie sequence of the selected Morph, click on ‘Movie Mode’. A movie sequence of the morph, which lasts approximately 10 seconds, will be shown. A different grading morph can be selected by clicking on a different complication in the vertical scrolling menu. The operating procedure as described above is identical for all 16 grading morphs. Clicking the ‘?’ (help) button in the top right corner of the window opens a separate window, which pictorially indicates how the program should be used. In this view, clicking on the ‘Close’ button in the upper right corner will re-open the main window platform from which any of the 16 grading morphs can again be selected. Simply close the window in the usual manner to quit the program.
Grading scales vs. morphs Technical differences The creation of printed scales involves computer-based scanning of the original artwork. The resulting RGB (Red/ Green/Blue) electronic files are used for storing and displaying colour images on computers. These must be converted to CMYK (Cyan/Magenta/Yellow/Black) electronic files, which are used to control CMYK-coloured inks when printing to paper. This conversion alters the stored colour information and results in a shift in the hue, saturation and value (brightness) of the colours of the
grading scales when they appear in printed form. Computer morphs, on the other hand, are viewed on a display monitor in RGB format. As a result of the above considerations, printed scales on paper might be expected to look different from computer morphs on a computer screen. Also, the individual images on the printed scales are relatively small (36 × 27 mm) and static, whereas the computer morph images on screen are relatively large (e.g. 97 × 79 mm on a 15 inch computer screen displaying 1024 × 768 pixels) and dynamic. In view of the differences described above, computer morphs may or may not be accurate or accord the same reliability as the generally accepted and well-established printed scales.
Performance differences In contrast with the recommended method of using printed scales – by interpolation to the score to the nearest 0.1 grading scale unit – no such interpolation is required when using continuously-variable computer morphs. Because there is no ‘guesswork’ required by way of interpolation of grades when using computer morphs, it might be expected that grading can be executed with greater reliability when using this tool versus printed scales. Efron et al.2 evaluated the performance of the Efron Grading Morphs computer program by (a) determining grading accuracy when using this program in relation to that obtained using the original five discrete printed images of the Efron Grading Scales, from which the morphs were constructed; and (b) comparing grading reliability between these two grading tools. This aim of this experiment was to determine whether computer morphs accord superior grading performance compared with printed scales. Nine experienced optometrists were each invited to grade – to the nearest 0.1 increment – an image of each of 16 contact lens complications, using printed Efron Grading Scales and the electronic Efron Grading Morphs computer program. This entire procedure was repeated approximately 2 weeks later, yielding a total database comprising 576 individual grading estimates. Good accuracy was 33
Chapter
Part I: Examination and Grading
3
2.0
Discrepancy (test–retest)
Discrepancy (test–retest)
2.0
1.0
0.0
–1.0
–2.0
0
1
2 Mean of test and retest
3
4
1.0
0.0
–1.0
–2.0
A
0
1
2 Mean of test and retest
3
4
B
Figure 3.2 Plot of test/retest grading discrepancies versus mean of the test/retest grading scores for all observers and ocular complications, for printed scales (A) and computer morphs (B). The solid line in each graph represents the mean of the test/retest discrepancies and the dotted lines represent the 95% confidence limits of the test/retest discrepancies (n = 144 for each graph). (Adapted from Efron N, Morgan PB, Jagpal R. Validation of computer morphs for grading contact lens complications. Ophthalmic Physiol Opt 2002;22:341–9.)
achieved using computer morphs, as evidenced by the similarity between the mean of the test and retest grading estimates for the printed scales (2.8 ± 0.7) and the computer morphs (2.6 ± 0.8). There was no difference in median reliability between the printed scales (±0.41) and the computer morphs (±0.43). Figure 3.2 depicts the grading discrepancies versus the mean of the test and retest grading estimates for the printed scales and computer morphs. It is clear by inspection that there is no general relation between the discrepancies and the means, indicating that grading reliability is unaffected by the severity of the condition being assessed using either grading tool. The differences in grading estimates between the two grading tools versus condition severity are presented in Figure 3.3. Again, there does not appear to be any relation between these discrepancies and condition severity.
Chong et al.3 reported inferior grading reliability (i.e. higher standard deviations) for grading conjunctival redness and papillary conjunctivitis, and no difference for grading corneal staining, when using printed scales versus computer morphs. However, the differences with respect to grading conjunctival redness and papillary conjunctivitis were small and the authors failed to verify the statistical significance of these differences. The study of Efron et al.2 found no overall statistically significant difference in grading reliability when grading a broad range of conditions using printed scales versus computer morphs. Computer morphs were thus considered to have been validated in view of their accuracy and reliability compared with printed scales. The notion that computer morphs offer superior grading reliability compared with printed scales must therefore be rejected.
The Efron Grading Tutor
Grading discrepancy
2.0 1.0 0.0 –1.0 –2.0
0
1
2 Mean grade estimate
3
4
Figure 3.3 Differences in grading estimates when using printed scales and computer morphs versus mean of grading estimates for all observers and ocular complications. The solid line represents the mean of the grading differences and the dotted lines represent the 95% confidence limits of the differences (n = 144). (Adapted from Efron N, Morgan PB, Jagpal R. Validation of computer morphs for grading contact lens complications. Ophthalmic Physiol Opt 2002;22:341–9.)
34
A Grading Tutor computer program has been developed for use by students, practitioners and researchers, and has a variety of potential applications. The program can be downloaded from the expertconsult website www. expertconsult.com using the code in the front of this book. Computer operating requirements are the same as for the ‘Efron Grading Morphs’ program, as outlined above. An important application of this program is to help practitioners assess, and possibly enhance, their grading performance. Specifically, the Efron Grading Tutor will do the following: • • • • • •
help hone your grading skills identify if you develop any grading bias determine your grading consistency calculate your grading accuracy compare your performance with that of experts explain what all this means clinically.
The Efron Grading Tutor has a similar interface to the Efron Grading Morphs program. It is assumed that the user is
Grading morphs familiar with the Efron Grading Morphs program, which provides instructions on general principles of how to grade the severity of a condition using morphs. The Tutor invites the user to grade the severity of 16 images of contact lens complications, twice in random sequence (32 gradings are performed). A given complication is graded by adjusting a slide bar until the severity of the condition as depicted in the morph matches that of the image under consideration. Severity is graded on a continuous scale, which ranges from 0.0 (normal) to 4.0 (severe). The numeric gradings are revealed to the user only after all 32 gradings have been attempted. On completion of this grading exercise, a series of windows appears which will give the user the information listed above. A supplementary ‘Help’ window can be called up, which presents further tips on grading and provides other useful information.
Program operation When the file ‘The Efron Grading Tutor’ is opened, the program will begin to run, and a title page appears. Click on ‘Skip’ to begin the program. In the next frame, enter your name and then click ‘Continue’ or hit the return key. You are now presented with a set of instructions, which explains how to use this program. Click ‘Start Tutor’ to begin grading. The first image to be graded appears, together with the matching morph. To grade the image, the slide bar beneath the grading morph movie frame is adjusted by clicking and holding the small rectangular slide bar control handle and moving it in the appropriate direction. When the slide bar control handle is moved to the right, the grading morph movie advances and the level of severity increases. Moving the slide bar control handle to the left will reverse the grading morph movie to a lower level of severity. The slide bar control handle can be moved back and forth in this way until the desired level of severity is achieved that matches that of the
image under consideration. The slide bar control handle can be released, re-engaged and moved as many times as required before advancing to the next image. The Efron Grading Tutor program window is shown in Figure 3.4. In this example, the user has been invited to grade an image of epithelial microcysts (the left hand image); the condition being graded (in this case, epithelial microcysts) is indicated on the bottom bar. The top bar indicates that this is the sixteenth image being graded. The slide bar control handle beneath the morph on the right hand side has been adjusted so that the level of severity displayed in the morph matches that of the left hand image; this numeric grade is deliberately not displayed (to avoid observer bias). When you are satisfied that you have matched the first image as best as possible, click the ‘Next’ button in the bottom right corner to advance to the second image. You can keep track of how many images you have graded (up to the maximum 32 images) by referring to the grading instruction along the top of the window. Click ‘Next’ again, and so on, until all 32 images have been graded. You can stop grading and restart the pro gram at any time by clicking on the ‘Restart’ button at bottom left. After grading the 32nd image, click on the ‘Results’ button in the bottom right corner. You will be led through a series of windows that will present you with information concerning your own grading performance. The first result you are presented with is your bias score. Click ‘Consistency’ to reveal your consistency score. An arrow will appear from the right and stop at your consistency score. An explanation is provided as to what this means (Figure 3.5). Click ‘Accuracy’ to reveal your accuracy scores. Your name, and a date and time stamp appear in the heading bar. You can scroll through all 16 complications by either (a) clicking on scroll handle and dragging it up or down; or (b) clicking on the up or down arrows, until the desired complication can be seen (each complication is named
Figure 3.4 The Efron Grading Tutor program window. In this example, the operator is invited to grade an image of epithelial microcysts.
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Part I: Examination and Grading
Figure 3.5 The Efron Grading Morphs program window for analysing grading consistency.
Figure 3.6 The Efron Grading Morphs program window, which gives scroll bar access to grading accuracy results for all 16 complications.
and is accompanied by a small image of that complication). For each complication, the mean (±1 standard deviation) grading estimate assigned by a panel of ten ‘experts’ is presented, along with your score and the difference between your score and that of the experts (Figure 3.6). A more detailed analysis of your grading performance with respect to any given complication can be analysed in detail by clicking anywhere along the row relating to the complication of interest. This will open the ‘Accuracy Analyser’ window for the chosen complication, which is stated at the bottom of the window (Figure 3.7). An image 36
of the complication that was graded is shown at left, and a grading morph movie frame of the complication appears on the right. The slide bar beneath the grading morph movie frame is adjusted in the usual way, and can be positioned with reference to the image at left and the grading level of the morph, which is indicated in a small window above the morph. The expert mean (±1 standard deviation) grade and the score you obtained when undertaking the masked grading previously is shown to the top left. In this way, you can dynamically compare your estimate with that of the experts.
Grading morphs
Figure 3.7 The Efron Grading Morphs program ‘Accuracy Analyser’ window. In this example, grading performance in relation to endothelial polymegethism is being analysed.
Figure 3.8 The Efron Grading Morphs program summary window, which gives scroll bar access to grading scores for all 16 complications. Grading bias, consistency and accuracy are indicated in boxes to the right.
Click the ‘Return’ button at bottom right to return to the ‘Grading Accuracy’ window. Another complication may be selected to go to the ‘Accuracy Analyser’ for that complication, and so on. The full set of grading accuracy scores can be printed out by hitting the ‘Print’ button. Clicking ‘Next’ takes you to a window that presents your average grading accuracy, which advises whether you typically grade higher, lower or the same as the group of experts. Clicking ‘Summary’ at the bottom right will take you to the next window which displays an overall summary of your results. Again, your name, and a date and time stamp appear in the heading bar. A table is presented, through
which you can scroll to view your first and repeat grading scores, and the score difference, for each of the 16 complications (Figure 3.8). Three results boxes appear on the right, which display your grading bias, consistency and accuracy. The full set of summary data can be printed out by hitting the ‘Print’ button. Click ‘Finish’ to end the program.
Conclusions Although there is no difference in grading performance when using printed scales versus computer morphs,2 there are clearly advantages of using both tools. Printed scales 37
Chapter
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Part I: Examination and Grading
offer the convenience of being readily accessible, whereby they may be kept next to the slit lamp biomicroscope. The use of computer morphs ensures that grading estimates will be made to the nearest 0.1 grading scale increment, obviating the tendency observed with printed scales to grade to the nearest whole-digit or half-digit increment. Computer morphs also offer the opportunity of integration with computer-based record-keeping systems. For example, a grading determined on a morphing tool can be entered automatically into a patient’s electronic record. Computer morphs have the advantage of allowing students and practitioners to better conceptualize the continuum and range of severity of various forms of contact lensinduced ocular pathology, and can be incorporated into self-help grading tutorial programs such as The Efron
38
Grading Tutor; in this context, computer morphs constitute a valuable learning , teaching and research tool.
References 1. Bailey IL, Bullimore MA, Raasch TW, Taylor HR. Clinical grading and the effects of scaling. Invest Ophthalmol Vis Sci 1991;32:422–32. 2. Efron N, Morgan PB, Jagpal R. Validation of computer morphs for grading contact lens complications. Ophthalmic Physiol Opt 2002;22:341–9. 3. Chong E, Simpson T, Fonn D. The repeatability of discrete and continuous anterior segment grading scales. Optom Vis Sci 2000;77:244–51.
3 C H A P T E R
Grading morphs
Although grading performance can be enhanced by interpolation to the nearest 0.1 grade unit,1 most practitioners find the process of mental interpolation between two discrete grading steps to be quite difficult, notwithstanding the fact that this task becomes easier with practice. One way of partially overcoming this difficulty is to re-engineer the grading scales into a continuous movie sequence, progress through which can be controlled by the clinician attempting to decide upon a grade. Modern computer software technology is available to undertake such tasks; the process of merging discrete images into a continuous movie sequence is known as ‘morphing’. The results of morphing will be familiar to many readers because this technique is used extensively in the visual arts to change the appearance of an object or person into another – for example, changing the face of one person seamlessly into that of another. Morphing is a technique that allows accurate interpolation of numerous progressively changing images between a ‘start’ and ‘end’ image, which are calculated pixel by pixel. When these images are presented one after the other in rapid succession, a movie or animation results, which allows one to observe the ‘start’ image being transformed into the ‘end’ image. The greater the number of interpolated images, the smoother will be the movie sequence. If the ‘start’ and ‘end’ images are not identical, the morphing technician can use software to link common elements in these images, which are identified manually. The only limitation to the number of interpolated images is the amount of computer memory available, because a high-resolution image in many colours can be memory-intensive.
Efron Grading Morphs Morphing animation sequences have been developed for each of the 16 complications depicted in Appendix A and have been incorporated into a computer program called ‘Efron Grading Morphs’. This can be downloaded from the expertconsult website www.expertconsult.com using the code in the front of this book. The ‘Efron Grading Morphs’ and ‘The Efron Grading Tutor’ (described below) will operate on IBM compatible © 2012 Elsevier Ltd
PC platforms (Windows 7, Vista, XP or higher) and Apple Macintosh platforms (Mac OS X or higher). The software may also operate on other computer configurations, although full testing has only been performed on the above configurations. The operation of the ‘Efron Grading Morphs’ program is described below.
Program operation When the ‘Efron Grading Morphs’ program is opened a title page appears. Click on ‘Skip’. A second window appears, from which you can choose any one of the 16 available grading morphs shown in the vertical scrolling menu along the left of the window. The choice of available morphs can be viewed by either (a) clicking on the scroll handle and dragging it up or down; or (b) clicking on the up or down arrows, until the desired complication can be seen. Once located, click on the desired complication. It will become highlighted in a yellow box, and the corresponding grading morph will be displayed in the centre of the window. The slide bar immediately beneath the grading morph can be adjusted by clicking and holding the small white rectangular slide bar control handle and moving it in the appropriate direction. When the slide bar control handle is moved to the right, the grading morph advances and the level of severity increases. Moving the slide bar control handle to the left will reverse the grading morph to a lower level of severity. The slide bar control handle can be moved back and forth in this way until the desired level of severity is achieved. The numeric grading indicating the level of severity of the condition being displayed is indicated in the right hand box as the grading morph is adjusted. This numeric grading is indicated to the nearest 0.1 grading scale unit, within the range from 0.0 (normal) to 4.0 (severe). The slide bar control handle can be released, re-engaged and moved as many times as required, before selecting an alternative grading morph, or quitting. The Efron Grading Morphs program window is shown in Figure 3.1. In this example, papillary conjunctivitis has been selected; this is highlighted by a yellow box in the
Grading morphs
Figure 3.1 Efron Grading Morphs program window. In this example, the papillary conjunctivitis morph is active.
vertical scrolling menu on the left hand side of the window. The slide bar control handle has been advanced to grade 2.7; this numeric grade is also displayed in the right hand panel. For masking purposes, the numeric grading can be ‘hidden’ by clicking on the ‘Hide Grade’ button beneath the numeric grade window. The numeric grading can then be revealed again by clicking on the same button, which is now called ‘Show Grade’. The operator can toggle between ‘Show Grade’ and ‘Hide Grade’ modes as often as required. To view a movie sequence of the selected Morph, click on ‘Movie Mode’. A movie sequence of the morph, which lasts approximately 10 seconds, will be shown. A different grading morph can be selected by clicking on a different complication in the vertical scrolling menu. The operating procedure as described above is identical for all 16 grading morphs. Clicking the ‘?’ (help) button in the top right corner of the window opens a separate window, which pictorially indicates how the program should be used. In this view, clicking on the ‘Close’ button in the upper right corner will re-open the main window platform from which any of the 16 grading morphs can again be selected. Simply close the window in the usual manner to quit the program.
Grading scales vs. morphs Technical differences The creation of printed scales involves computer-based scanning of the original artwork. The resulting RGB (Red/ Green/Blue) electronic files are used for storing and displaying colour images on computers. These must be converted to CMYK (Cyan/Magenta/Yellow/Black) electronic files, which are used to control CMYK-coloured inks when printing to paper. This conversion alters the stored colour information and results in a shift in the hue, saturation and value (brightness) of the colours of the
grading scales when they appear in printed form. Computer morphs, on the other hand, are viewed on a display monitor in RGB format. As a result of the above considerations, printed scales on paper might be expected to look different from computer morphs on a computer screen. Also, the individual images on the printed scales are relatively small (36 × 27 mm) and static, whereas the computer morph images on screen are relatively large (e.g. 97 × 79 mm on a 15 inch computer screen displaying 1024 × 768 pixels) and dynamic. In view of the differences described above, computer morphs may or may not be accurate or accord the same reliability as the generally accepted and well-established printed scales.
Performance differences In contrast with the recommended method of using printed scales – by interpolation to the score to the nearest 0.1 grading scale unit – no such interpolation is required when using continuously-variable computer morphs. Because there is no ‘guesswork’ required by way of interpolation of grades when using computer morphs, it might be expected that grading can be executed with greater reliability when using this tool versus printed scales. Efron et al.2 evaluated the performance of the Efron Grading Morphs computer program by (a) determining grading accuracy when using this program in relation to that obtained using the original five discrete printed images of the Efron Grading Scales, from which the morphs were constructed; and (b) comparing grading reliability between these two grading tools. This aim of this experiment was to determine whether computer morphs accord superior grading performance compared with printed scales. Nine experienced optometrists were each invited to grade – to the nearest 0.1 increment – an image of each of 16 contact lens complications, using printed Efron Grading Scales and the electronic Efron Grading Morphs computer program. This entire procedure was repeated approximately 2 weeks later, yielding a total database comprising 576 individual grading estimates. Good accuracy was 33
Chapter
Part I: Examination and Grading
3
2.0
Discrepancy (test–retest)
Discrepancy (test–retest)
2.0
1.0
0.0
–1.0
–2.0
0
1
2 Mean of test and retest
3
4
1.0
0.0
–1.0
–2.0
A
0
1
2 Mean of test and retest
3
4
B
Figure 3.2 Plot of test/retest grading discrepancies versus mean of the test/retest grading scores for all observers and ocular complications, for printed scales (A) and computer morphs (B). The solid line in each graph represents the mean of the test/retest discrepancies and the dotted lines represent the 95% confidence limits of the test/retest discrepancies (n = 144 for each graph). (Adapted from Efron N, Morgan PB, Jagpal R. Validation of computer morphs for grading contact lens complications. Ophthalmic Physiol Opt 2002;22:341–9.)
achieved using computer morphs, as evidenced by the similarity between the mean of the test and retest grading estimates for the printed scales (2.8 ± 0.7) and the computer morphs (2.6 ± 0.8). There was no difference in median reliability between the printed scales (±0.41) and the computer morphs (±0.43). Figure 3.2 depicts the grading discrepancies versus the mean of the test and retest grading estimates for the printed scales and computer morphs. It is clear by inspection that there is no general relation between the discrepancies and the means, indicating that grading reliability is unaffected by the severity of the condition being assessed using either grading tool. The differences in grading estimates between the two grading tools versus condition severity are presented in Figure 3.3. Again, there does not appear to be any relation between these discrepancies and condition severity.
Chong et al.3 reported inferior grading reliability (i.e. higher standard deviations) for grading conjunctival redness and papillary conjunctivitis, and no difference for grading corneal staining, when using printed scales versus computer morphs. However, the differences with respect to grading conjunctival redness and papillary conjunctivitis were small and the authors failed to verify the statistical significance of these differences. The study of Efron et al.2 found no overall statistically significant difference in grading reliability when grading a broad range of conditions using printed scales versus computer morphs. Computer morphs were thus considered to have been validated in view of their accuracy and reliability compared with printed scales. The notion that computer morphs offer superior grading reliability compared with printed scales must therefore be rejected.
The Efron Grading Tutor
Grading discrepancy
2.0 1.0 0.0 –1.0 –2.0
0
1
2 Mean grade estimate
3
4
Figure 3.3 Differences in grading estimates when using printed scales and computer morphs versus mean of grading estimates for all observers and ocular complications. The solid line represents the mean of the grading differences and the dotted lines represent the 95% confidence limits of the differences (n = 144). (Adapted from Efron N, Morgan PB, Jagpal R. Validation of computer morphs for grading contact lens complications. Ophthalmic Physiol Opt 2002;22:341–9.)
34
A Grading Tutor computer program has been developed for use by students, practitioners and researchers, and has a variety of potential applications. The program can be downloaded from the expertconsult website www. expertconsult.com using the code in the front of this book. Computer operating requirements are the same as for the ‘Efron Grading Morphs’ program, as outlined above. An important application of this program is to help practitioners assess, and possibly enhance, their grading performance. Specifically, the Efron Grading Tutor will do the following: • • • • • •
help hone your grading skills identify if you develop any grading bias determine your grading consistency calculate your grading accuracy compare your performance with that of experts explain what all this means clinically.
The Efron Grading Tutor has a similar interface to the Efron Grading Morphs program. It is assumed that the user is
Grading morphs familiar with the Efron Grading Morphs program, which provides instructions on general principles of how to grade the severity of a condition using morphs. The Tutor invites the user to grade the severity of 16 images of contact lens complications, twice in random sequence (32 gradings are performed). A given complication is graded by adjusting a slide bar until the severity of the condition as depicted in the morph matches that of the image under consideration. Severity is graded on a continuous scale, which ranges from 0.0 (normal) to 4.0 (severe). The numeric gradings are revealed to the user only after all 32 gradings have been attempted. On completion of this grading exercise, a series of windows appears which will give the user the information listed above. A supplementary ‘Help’ window can be called up, which presents further tips on grading and provides other useful information.
Program operation When the file ‘The Efron Grading Tutor’ is opened, the program will begin to run, and a title page appears. Click on ‘Skip’ to begin the program. In the next frame, enter your name and then click ‘Continue’ or hit the return key. You are now presented with a set of instructions, which explains how to use this program. Click ‘Start Tutor’ to begin grading. The first image to be graded appears, together with the matching morph. To grade the image, the slide bar beneath the grading morph movie frame is adjusted by clicking and holding the small rectangular slide bar control handle and moving it in the appropriate direction. When the slide bar control handle is moved to the right, the grading morph movie advances and the level of severity increases. Moving the slide bar control handle to the left will reverse the grading morph movie to a lower level of severity. The slide bar control handle can be moved back and forth in this way until the desired level of severity is achieved that matches that of the
image under consideration. The slide bar control handle can be released, re-engaged and moved as many times as required before advancing to the next image. The Efron Grading Tutor program window is shown in Figure 3.4. In this example, the user has been invited to grade an image of epithelial microcysts (the left hand image); the condition being graded (in this case, epithelial microcysts) is indicated on the bottom bar. The top bar indicates that this is the sixteenth image being graded. The slide bar control handle beneath the morph on the right hand side has been adjusted so that the level of severity displayed in the morph matches that of the left hand image; this numeric grade is deliberately not displayed (to avoid observer bias). When you are satisfied that you have matched the first image as best as possible, click the ‘Next’ button in the bottom right corner to advance to the second image. You can keep track of how many images you have graded (up to the maximum 32 images) by referring to the grading instruction along the top of the window. Click ‘Next’ again, and so on, until all 32 images have been graded. You can stop grading and restart the pro gram at any time by clicking on the ‘Restart’ button at bottom left. After grading the 32nd image, click on the ‘Results’ button in the bottom right corner. You will be led through a series of windows that will present you with information concerning your own grading performance. The first result you are presented with is your bias score. Click ‘Consistency’ to reveal your consistency score. An arrow will appear from the right and stop at your consistency score. An explanation is provided as to what this means (Figure 3.5). Click ‘Accuracy’ to reveal your accuracy scores. Your name, and a date and time stamp appear in the heading bar. You can scroll through all 16 complications by either (a) clicking on scroll handle and dragging it up or down; or (b) clicking on the up or down arrows, until the desired complication can be seen (each complication is named
Figure 3.4 The Efron Grading Tutor program window. In this example, the operator is invited to grade an image of epithelial microcysts.
35
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Part I: Examination and Grading
Figure 3.5 The Efron Grading Morphs program window for analysing grading consistency.
Figure 3.6 The Efron Grading Morphs program window, which gives scroll bar access to grading accuracy results for all 16 complications.
and is accompanied by a small image of that complication). For each complication, the mean (±1 standard deviation) grading estimate assigned by a panel of ten ‘experts’ is presented, along with your score and the difference between your score and that of the experts (Figure 3.6). A more detailed analysis of your grading performance with respect to any given complication can be analysed in detail by clicking anywhere along the row relating to the complication of interest. This will open the ‘Accuracy Analyser’ window for the chosen complication, which is stated at the bottom of the window (Figure 3.7). An image 36
of the complication that was graded is shown at left, and a grading morph movie frame of the complication appears on the right. The slide bar beneath the grading morph movie frame is adjusted in the usual way, and can be positioned with reference to the image at left and the grading level of the morph, which is indicated in a small window above the morph. The expert mean (±1 standard deviation) grade and the score you obtained when undertaking the masked grading previously is shown to the top left. In this way, you can dynamically compare your estimate with that of the experts.
Grading morphs
Figure 3.7 The Efron Grading Morphs program ‘Accuracy Analyser’ window. In this example, grading performance in relation to endothelial polymegethism is being analysed.
Figure 3.8 The Efron Grading Morphs program summary window, which gives scroll bar access to grading scores for all 16 complications. Grading bias, consistency and accuracy are indicated in boxes to the right.
Click the ‘Return’ button at bottom right to return to the ‘Grading Accuracy’ window. Another complication may be selected to go to the ‘Accuracy Analyser’ for that complication, and so on. The full set of grading accuracy scores can be printed out by hitting the ‘Print’ button. Clicking ‘Next’ takes you to a window that presents your average grading accuracy, which advises whether you typically grade higher, lower or the same as the group of experts. Clicking ‘Summary’ at the bottom right will take you to the next window which displays an overall summary of your results. Again, your name, and a date and time stamp appear in the heading bar. A table is presented, through
which you can scroll to view your first and repeat grading scores, and the score difference, for each of the 16 complications (Figure 3.8). Three results boxes appear on the right, which display your grading bias, consistency and accuracy. The full set of summary data can be printed out by hitting the ‘Print’ button. Click ‘Finish’ to end the program.
Conclusions Although there is no difference in grading performance when using printed scales versus computer morphs,2 there are clearly advantages of using both tools. Printed scales 37
Chapter
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Part I: Examination and Grading
offer the convenience of being readily accessible, whereby they may be kept next to the slit lamp biomicroscope. The use of computer morphs ensures that grading estimates will be made to the nearest 0.1 grading scale increment, obviating the tendency observed with printed scales to grade to the nearest whole-digit or half-digit increment. Computer morphs also offer the opportunity of integration with computer-based record-keeping systems. For example, a grading determined on a morphing tool can be entered automatically into a patient’s electronic record. Computer morphs have the advantage of allowing students and practitioners to better conceptualize the continuum and range of severity of various forms of contact lensinduced ocular pathology, and can be incorporated into self-help grading tutorial programs such as The Efron
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Grading Tutor; in this context, computer morphs constitute a valuable learning , teaching and research tool.
References 1. Bailey IL, Bullimore MA, Raasch TW, Taylor HR. Clinical grading and the effects of scaling. Invest Ophthalmol Vis Sci 1991;32:422–32. 2. Efron N, Morgan PB, Jagpal R. Validation of computer morphs for grading contact lens complications. Ophthalmic Physiol Opt 2002;22:341–9. 3. Chong E, Simpson T, Fonn D. The repeatability of discrete and continuous anterior segment grading scales. Optom Vis Sci 2000;77:244–51.