Shehzad A. Naroo 1 , Fabrizio Zeri 1 , Assunta Di Vizio², Maurizio Guida², Anastasia Rotondi² 1 School of Life and Health Sciences. Aston University, Birmingham UK. 2 Degree Course in Optics and Optometry, Department of Sciences. Roma TRE University, Rome, Italy Corneal topography in assessing multifocal CL ceration For the RE almost all topographic methods estimate consistently a more temporal (more negative value of x) and higher position of CLs (more positive value of y) respect to SL assessment (paired t-test, p<0.05). However the difference was clinically negligible (0.16±0.36 mm horizontally, 0.23±0.48 vertically). No statistical differences were found in the LE. Are the topographic Algorithms to analyse centration equivalent? T max , T abs , T 0.3 and T 0.2 resulted almost equivalent in detecting the centre coordinates. For the RE the one-way Anova didn’t show any difference among 4 procedures both for x and y coordinates; F 3,21 =1.45 (p=0.24) and F 3,21 =2.17 (p=0.10) respectively. For the LE the one-way Anova didn’t show any difference among 4 procedures for y coordinate (one-way Anova F 3,21 =1.60; p=0.20) but a significant difference was found for x coordinate (one- way Anova F 3,21 =2.90; p=0.042). Method Introduction Many people wearing multifocal contact lenses (MCLs) for presbyopia correction may complain about a reduction in vision quality (Rajagopalan et al, 2006). Centration is one of the most relevant factors able to affect the efficacy of correction. Decentration of a MCL with respect to the pupil centre will cause unwanted aberrations, mainly represented by coma (Dave, 2015). It has been recently suggested that corneal topography performed over a MCL could be a useful method to evaluate lens centration (Lampa et al, 2012) and this could help in clinical setting in understanding the results of the fitting and minimising follow-ups (Miller and Brujic, 2012). However, no information is available about the reliability of this method. Accuracy L 0.34 0.47 0.29 0.29 0.31 0.10 0.21 0.06 0.04 0.03 0.50 0.40 0.30 0.20 0.10 0.00 0.10 0.20 0.30 0.40 0.50 SL Tmax Tabs T0.3 T0.2 Decentra(on respect to pupil centre (mm) x coordinate y coordinate Inter-observer reliability Intra-observer reliability Results Intra-class correlation coefficient (ICC) was calculated, for each single operator, among the 3 readings achieved in each manual procedure of CL assessment of centration with Topography (T abs , T 0.3 and T 0.2 ). ICC was obtained for each coordinate (x, y) and for each eye. ICCs were very good (between 0.75 and 0.98) in 3 operators and moderate (between 0.49 and 0.92) in the fourth. Amongst 4 operators a one-way ANOVAs for repeated measures showed no differences in almost all the condition that is proof of a very good Inter-observer reliability. Only in RE for x coordinate achieved with T abs and T 0.3 the means resulted significantly different F 3,21 =4.01; p=0.01 and F 3,21 =2.70; p=0.05 respectively) . In both cases pairwise comparison showed that operator 2 resulted different from operator 1, 3 and 4. Shehzad Naroo [email protected]> MCLs centre coordinates (x, y) respect to pupil centre as assessed by SL, T max T abs, T 0.3 and T 0.2 for RE (top) and LE(bottom) respectively. T abs, T 0.3 and T 0.2 coordinates are the averages of the measurements of the 4 operators. Paired comparison (t-test) significance between each topographic assessment of a single coordinate and SL assessment are reported with * at the level p<0.05. R 0.11 0.33 0.24 0.26 0.27 0.18 0.18 0.01 0.01 0.01 0.5 0.4 0.3 0.2 0.1 0 0.1 0.2 0.3 0.4 0.5 SL Tmax Tabs T0.3 T0.2 Decentra(on respect to pupil centre (mm) x coordinate y coordinate * * * * * * * L 0.28 0.25 0.27 0.38 0.13 0.00 0.09 0.00 0.50 0.40 0.30 0.20 0.10 0.00 0.10 0.20 0.30 0.40 0.50 Operator 1 Operator 2 Operator 3 Operator 4 Decentra(on respect to pupil centre (mm) x coordinate y coordinate T 0.3 : adjustable 0.3 mm T abs : absolute T 0.2 : adjustable 0.2 mm L 0.28 0.25 0.27 0.38 0.12 0.01 0.08 0.01 0.50 0.40 0.30 0.20 0.10 0.00 0.10 0.20 0.30 0.40 0.50 Operator 1 Operator 2 Operator 3 Operator 4 Decentra(on respect to pupil centre (mm) x coordinate y coordinate R 0.26 0.23 0.30 0.29 0.04 0.03 0.03 0.01 0.5 0.4 0.3 0.2 0.1 0 0.1 0.2 0.3 0.4 0.5 Operator 1 Operator 2 Operator 3 Operator 4 Decentra(on respect to pupil centre (mm) x coordinate y coordinate L 0.30 0.28 0.28 0.39 0.09 0.03 0.10 0.03 0.50 0.40 0.30 0.20 0.10 0.00 0.10 0.20 0.30 0.40 0.50 Operator 1 Operator 2 Operator 3 Operator 4 Decentra(on respect to pupil centre (mm) x coordinate y coordinate R 0.22 0.18 0.27 0.29 0.04 0.03 0.01 0 0.5 0.4 0.3 0.2 0.1 0 0.1 0.2 0.3 0.4 0.5 Operator 1 Operator 2 Operator 3 Operator 4 Decentra(on respect to pupil centre (mm) x coordinate y coordinate ANOVA p=0.01 R 0.26 0.21 0.30 0.29 0.05 0.06 0.02 0.02 0.5 0.4 0.3 0.2 0.1 0 0.1 0.2 0.3 0.4 0.5 Operator 1 Operator 2 Operator 3 Operator 4 Decentra(on respect to pupil centre (mm) x coordinate y coordinate ANOVA p=0.01 Multifocal CLs centre coordinates (x, y) respect to pupil centre achieved from the 4 operators with the 3 modalities of Topographic assessment of MCL centration (T abs , T 0.3 and T 0.2 ) for RE and LE. ICC (single measures) with 95% CI . A photo-editing digital procedure was used to assess the position (x and y coordinates) of the MCL centre with respect to pupil centre, as taken from the SL photo. Starting with the original digital picture the edges of MCLs were traced with an Image Editor Program (1). Then the centre of MCL and the centre of the pupil were detected through the overlapping of a circular digital templates aligned to the circumference of MCL and pupil respectively (2). The two centres were connected with a digital line and its length in pixel was converted in mm to get the distance between the two centres (i.e. the position of the MCL centre with respect to pupil centre). 1 2 Slit Lamp Assessment of MCL centre (SL) The possibility to assess MCL centration by performing a topography over the lens is an accurate method in the MCL design investigated in this study, and the authors suggest that the techniques should be expandable to other MCL designs. Furthermore, inter and intra-practitioner reliability showed by manual procedures appeared very good and not affected by operator experience. Conclusion References Correspondence • Rajagopalan AS et al. Visual performance of subjects wearing presbyopic contact lenses. Optom Vis Sci; 2006 83: 611-615. • Dave T. Understanding multifocals and getting them to work. Optician 2015; 249: 12-17. • Lampa M, et al. Assessing multifocal soft contact lens centration with the aid of corneal topography. Poster presented at 2012 Global Specialty Lens Symposium, January 26-29, 2012; Las Vegas, NV. • Miller JR, Brujic M Minimize follow-up for multifocal contacts: do you hesitate to offer multifocal contact lenses to your presbyopes? Review of Optometry; 2012 149: 48-52. Dr. Fabrizio Zeri was funded with the support of the European Union under a Marie Curie Intra-European Fellowship for Career Development (FP7), Grant Agreement number 622786. To evaluate accuracy and reliability (inter and intra-observer) in MCLs centration assessment with topography performed over the CL. Purpose Dr Shehzad Naroo [email protected] Twenty-two subjects (11 males) aged 22.8±1.9 years (range 20.8-27.0 years) were recruited. Daily-disposable MCLs (Fusion 1 day Presbyo, Safilens Staranzano, Italy) in Filcon IV with 60% of water content, BOZR of 8.6 mm, TD of 14.5 mm, Dk/t (×10 -9 ) of 29, and CT of 0.07 mm (@ -3.00D) were fitted on both eyes of the participants. MCLs were all plano powered (Focal Equivalent) for distance. For any MCL fitted in each subject, a slit lamp (SL) digital picture (FS-3, Nikon) and a videokeratography (Eye-Top, CSO) were taken in a rapid but randomised sequence. Both procedures were performed in a way to assure the alignment between line of sight and optical axes of the instruments. Quantitative topographic assessment of MCL centre (T max ) The position of the MCL centre (x and y coordinates) was automatically detected as the point of maximum curvature from the videokeratography. T 0.3 : tangential adjustable 0.3 mm T abs : tangential absolute T 0.2 : tangential adjustable 0.2 mm Qualitative topographic assessment of MCL centre Two expert eye care practitioners (ECPs) (operators 1 and 2) each with more than 20 years of experience in CL practice and two young ECPs (operators 3 and 4) with less than 5 years of experience in CL practice analysed the topographic pictures in order to assess MCL centration using three different algorithms to represent the topographic map: tangential absolute (T abs ), tangential adjustable with a step of 0.30 mm (T 0.30 ) and tangential adjustable with a step of 0.20 mm (T 0.20 ). They used a template with different circles to overlap to the map to detect the position of the MCL centre. Once the position was detected, they aligned the cursor in the centre of the lens and the x and y coordinates respect to pupil centre were obtained on the topographic software. The sequence of the 3 algorithm used was randomised for each topographic map. The operators repeated the assessment other 2 times with 15 days delay. 1 2 T abs T 0.3 T 0.2 RE LE RE LE RE LE x y x y x y x y x y x y Operator 1 0.97 0.94 0.96 0.98 0.97 0.98 0.96 0.97 0.97 0.77 0.95 0.78 Operator 2 0.90 0.79 0.68 0.57 0.90 0.92 0.78 0.49 0.89 0.89 0.74 0.60 Operator 3 0.96 0.92 0.91 0.95 0.95 0.94 0.92 0.94 0.96 0.90 0.92 0.95 Operator 4 0.90 0.88 0.85 0.72 0.85 0.81 0.84 0.74 0.90 0.93 0.83 0.75
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Shehzad A. Naroo1, Fabrizio Zeri1, Assunta Di Vizio², Maurizio Guida², Anastasia Rotondi² 1 School of Life and Health Sciences. Aston University, Birmingham UK. 2 Degree Course in Optics and Optometry, Department of Sciences. Roma TRE University, Rome, Italy
Corneal topography in assessing multifocal CL ceration
For the RE almost all topographic methods estimate consistently a more temporal (more negative value of x) and higher position of CLs (more positive value of y) respect to SL assessment (paired t-test, p<0.05). However the difference was clinically negligible (0.16±0.36 mm horizontally, 0.23±0.48 vertically). No statistical differences were found in the LE. Are the topographic Algorithms to analyse centration equivalent? Tmax, Tabs, T0.3 and T0.2 resulted almost equivalent in detecting the centre coordinates. For the RE the one-way Anova didn’t show any difference among 4 procedures both for x and y coordinates; F3,21=1.45 (p=0.24) and F3,21=2.17 (p=0.10) respectively. For the LE the one-way Anova didn’t show any difference among 4 procedures for y coordinate (one-way Anova F3,21=1.60; p=0.20) but a significant difference was found for x coordinate (one-way Anova F3,21=2.90; p=0.042).
Method
IntroductionMany people wearing multifocal contact lenses (MCLs) for presbyopia correction may complain about a reduction in vision quality (Rajagopalan et al, 2006). Centration is one of the most relevant factors able to affect the efficacy of correction. Decentration of a MCL with respect to the pupil centre will cause unwanted aberrations, mainly represented by coma (Dave, 2015). It has been recently suggested that corneal topography performed over a MCL could be a useful method to evaluate lens centration (Lampa et al, 2012) and this could help in clinical setting in understanding the results of the fitting and minimising follow-ups (Miller and Brujic, 2012). However, no information is available about the reliability of this method.
Accuracy
L 0.34
0.47
0.29 0.29 0.31
-‐0.10
0.21
0.06 0.04 0.03
-‐0.50
-‐0.40
-‐0.30
-‐0.20
-‐0.10
0.00
0.10
0.20
0.30
0.40
0.50
SL Tmax Tabs T0.3 T0.2
Decentra(o
n respect to pu
pil cen
tre (m
m)
x coordinate
y coordinate
Inter-observer reliability
Intra-observer reliability
Results
Intra-class correlation coefficient (ICC) was calculated, for each single operator, among the 3 readings achieved in each manual procedure of CL assessment of centration with Topography (Tabs, T0.3 and T0.2). ICC was obtained for each coordinate (x, y) and for each eye. ICCs were very good (between 0.75 and 0.98) in 3 operators and moderate (between 0.49 and 0.92) in the fourth.
Amongst 4 operators a one-way ANOVAs for repeated measures showed no differences in almost all the condition that is proof of a very good Inter-observer reliability. Only in RE for x coordinate achieved with Tabs and T0.3 the means resulted significantly different F3,21=4.01; p=0.01 and F3,21=2.70; p=0.05 respectively) . In both cases pairwise comparison showed that operator 2 resulted different from operator 1, 3 and 4.
Shehzad Naroo [email protected]>
MCLs centre coordinates (x, y) respect to pupil centre as assessed by SL, Tmax Tabs, T0.3 and T0.2 for RE (top) and LE(bottom) respectively. Tabs, T0.3 and T0.2 coordinates are the averages of the measurements of the 4 operators. Paired comparison (t-test) significance between each topographic assessment of a single coordinate and SL assessment are reported with * at the level p<0.05.
R -‐0.11
-‐0.33
-‐0.24 -‐0.26 -‐0.27
-‐0.18
0.18
0.01 0.01 0.01
-‐0.5
-‐0.4
-‐0.3
-‐0.2
-‐0.1
0
0.1
0.2
0.3
0.4
0.5
SL Tmax Tabs T0.3 T0.2
Decentra(o
n respect to pu
pil cen
tre (m
m)
x coordinate
y coordinate
*
*
* *
* *
* L 0.28 0.25 0.27
0.38
0.13
0.00
0.09
0.00
-‐0.50
-‐0.40
-‐0.30
-‐0.20
-‐0.10
0.00
0.10
0.20
0.30
0.40
0.50
Operator 1 Operator 2 Operator 3 Operator 4
Decentra(o
n respect to pu
pil cen
tre (m
m)
x coordinate
y coordinate
T0.3: adjustable 0.3 mm
Tabs : absolute
T0.2: adjustable 0.2 mm
L 0.28 0.25 0.27
0.38
0.12
-‐0.01
0.08
-‐0.01
-‐0.50
-‐0.40
-‐0.30
-‐0.20
-‐0.10
0.00
0.10
0.20
0.30
0.40
0.50
Operator 1 Operator 2 Operator 3 Operator 4
Decentra(o
n respect to pu
pil cen
tre (m
m)
x coordinate
y coordinate
R -‐0.26 -‐0.23
-‐0.30 -‐0.29
0.04
-‐0.03 0.03 0.01
-‐0.5
-‐0.4
-‐0.3
-‐0.2
-‐0.1
0
0.1
0.2
0.3
0.4
0.5
Operator 1 Operator 2 Operator 3 Operator 4
Decentra(o
n respect to pu
pil cen
tre (m
m)
x coordinate
y coordinate
L 0.30 0.28 0.28
0.39
0.09
-‐0.03
0.10
-‐0.03
-‐0.50
-‐0.40
-‐0.30
-‐0.20
-‐0.10
0.00
0.10
0.20
0.30
0.40
0.50
Operator 1 Operator 2 Operator 3 Operator 4
Decentra(o
n respect to pu
pil cen
tre (m
m)
x coordinate
y coordinate
R -‐0.22 -‐0.18
-‐0.27 -‐0.29
0.04
-‐0.03 0.01 0
-‐0.5
-‐0.4
-‐0.3
-‐0.2
-‐0.1
0
0.1
0.2
0.3
0.4
0.5
Operator 1 Operator 2 Operator 3 Operator 4
Decentra(o
n respect to pu
pil cen
tre (m
m)
x coordinate
y coordinate
ANOVA p=0.01
R -‐0.26 -‐0.21
-‐0.30 -‐0.29
0.05
-‐0.06
0.02 0.02
-‐0.5
-‐0.4
-‐0.3
-‐0.2
-‐0.1
0
0.1
0.2
0.3
0.4
0.5
Operator 1 Operator 2 Operator 3 Operator 4
Decentra(o
n respect to pu
pil cen
tre (m
m)
x coordinate
y coordinate
ANOVA p=0.01
Multifocal CLs centre coordinates (x, y) respect to pupil centre achieved from the 4 operators with the 3 modalities of Topographic assessment of MCL centration (Tabs, T0.3 and T0.2) for RE and LE.
ICC (single measures) with 95% CI .
A photo-editing digital procedure was used to assess the position (x and y coordinates) of the MCL centre with respect to pupil centre, as taken from the SL photo. Starting with the original digital picture the edges of MCLs were traced with an Image Editor Program (1). Then the centre of MCL and the centre of the pupil were detected through the overlapping of a circular digital templates aligned to the circumference of MCL and pupil respectively (2). The two centres were connected with a digital line and its length in pixel was converted in mm to get the distance between the two centres (i.e. the position of the MCL centre with respect to pupil centre).
1 2
Slit Lamp Assessment of MCL centre (SL)
The possibility to assess MCL centration by performing a topography over the lens is an accurate method in the MCL design investigated in this study, and the authors suggest that the techniques should be expandable to other MCL designs. Furthermore, inter and intra-practitioner reliability showed by manual procedures appeared very good and not affected by operator experience.
Conclusion
References Correspondence
• Rajagopalan AS et al. Visual performance of subjects wearing presbyopic contact lenses. Optom Vis Sci; 2006 83: 611-615. • Dave T. Understanding multifocals and getting them to work. Optician 2015; 249: 12-17. • Lampa M, et al. Assessing multifocal soft contact lens centration with the aid of corneal topography. Poster presented at 2012
Global Specialty Lens Symposium, January 26-29, 2012; Las Vegas, NV. • Miller JR, Brujic M Minimize follow-up for multifocal contacts: do you hesitate to offer multifocal contact lenses to your
presbyopes? Review of Optometry; 2012 149: 48-52. Dr. Fabrizio Zeri was funded with the support of the European Union under a Marie Curie Intra-European Fellowship for Career Development (FP7), Grant Agreement number 622786.
To evaluate accuracy and reliability (inter and intra-observer) in MCLs centration assessment with topography performed over the CL.
Purpose
Dr Shehzad Naroo [email protected]
Twenty-two subjects (11 males) aged 22.8±1.9 years (range 20.8-27.0 years) were recruited.
Daily-disposable MCLs (Fusion 1 day Presbyo, Safilens Staranzano, Italy) in Filcon IV with 60% of water content, BOZR of 8.6 mm, TD of 14.5 mm, Dk/t (×10-9) of 29, and CT of 0.07 mm (@ -3.00D) were fitted on both eyes of the participants. MCLs were all plano powered (Focal Equivalent) for distance.
For any MCL fitted in each subject, a slit lamp (SL) digital picture (FS-3, Nikon) and a videokeratography (Eye-Top, CSO) were taken in a rapid but randomised sequence. Both procedures were performed in a way to assure the alignment between line of sight and optical axes of the instruments.
Quantitative topographic assessment of MCL centre (Tmax)
The position of the MCL centre (x and y coordinates) was automatically detected as the point of maximum curvature from the videokeratography.
T0.3: tangential adjustable 0.3 mm
Tabs: tangential absolute T0.2: tangential adjustable 0.2 mm
Qualitative topographic assessment of MCL centre Two expert eye care practitioners (ECPs) (operators 1 and 2) each with more than 20 years of experience in CL practice and two young ECPs (operators 3 and 4) with less than 5 years of experience in CL practice analysed the topographic pictures
in order to assess MCL centration using three different algorithms to represent the topographic map: tangential absolute (Tabs), tangential adjustable with a step of 0.30 mm (T0.30) and tangential adjustable with a step of 0.20 mm (T0.20). They used a template with different circles to overlap to the map to detect the position of the MCL centre. Once the position was detected, they aligned the cursor in the centre of the lens and the x and y coordinates respect to pupil centre were obtained on the topographic software. The sequence of the 3 algorithm used was randomised for each topographic map. The operators repeated the assessment other 2 times with 15 days delay.
1
2
Tabs T0.3 T0.2 RE LE RE LE RE LE
x y x y x y x y x y x y Operator 1 0.97 0.94 0.96 0.98 0.97 0.98 0.96 0.97 0.97 0.77 0.95 0.78 Operator 2 0.90 0.79 0.68 0.57 0.90 0.92 0.78 0.49 0.89 0.89 0.74 0.60 Operator 3 0.96 0.92 0.91 0.95 0.95 0.94 0.92 0.94 0.96 0.90 0.92 0.95 Operator 4 0.90 0.88 0.85 0.72 0.85 0.81 0.84 0.74 0.90 0.93 0.83 0.75
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