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Matanglawin Protocol

Thesis Defense Presentation

Yel Cordova

on 30 January 2013

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Transcript of Matanglawin Protocol

Introduction Literature Discussion Limitations Recommendations Results Problem Matanglawin Protocol Weakness of research study Test used Thesis Defense Presentation Limitations and Delimitations Implications Conclusions Uncontrolled factors Modified methodology Different school environments Eye patch occluder Tester inconsistency null: there is no statistically significant difference between scores of teachers and of optometrists Varying structures and placements of classrooms Unpredictable student departure Different times and distances Fatigue* Control: Sufficient resting time Presence of parents/guardians No second testing Control: Replace student Insufficient manpower No standard occluder Control: Consistent use among testers Unexpected events caused problems Replace testers Optometrists Teachers New optometrists Control: Emergency reliability testing New Teachers Control: Impromptu training Fatigue* Control: Regular breaks Strong agreement (ICC) Strong performance of teachers Teachers as VA testers Improved detection of poor VA Preventable blindness Statistically significant difference in VA scores Question of sustainability Question of improvement mean age = 62.37 months
median age = 62 months 103 males + 103 females

203 kindergarten students Demographics VA initially listed as fraction (e.g., 20/25)
but recorded as LogMAR values
(+0.1) VA initially listed as fraction (e.g., 20/25)
but recorded as LogMAR values
(+0.1) VA initially listed as fraction (e.g., 20/25)
but recorded as LogMAR values
(+0.1) Optometrist Teacher Right Eye (OD) Optometrist Teacher Left Eye (OS) Centered distribution on 0.0
relatively normal
majority diagnosed children as normal

Skewed to the right distribution for optometrists
teachers' tendencies to classify more children as having poor VA
overdiagnosis of children Analysis VA initially listed as fraction (e.g., 20/25)
but recorded as LogMAR values
(+0.1) VA initially listed as fraction (e.g., 20/25) but recorded as LogMAR values (+0.1) Visual Acuity Scores Pass/Fail criteria pass: VA < 0.3 logMAR  1
fail: VA ≥ 0.3 logMAR  2 The main purpose of visual acuity assessment in children is to detect amblyopia and to control its treatment Amblyopia and IAD IAD > 1 dB (greater than 1 line difference)
findings of Gräf et al. : 48 out of 55 amblyopes
findings of this study:
optometrists: 26 out of 206 (12.62%) pairs of eyes
teachers: 48 out of 206 (23.70%) pairs of eye
overdiagnosis of possible amblyopes by the teachers Analysis of Visual Acuity Scores Raw Agreement McNemar’s Pearson’s Crosstab of Pass and Fail VA scores for the left eye Crosstab of Pass and Fail VA scores for the right eye proportion of overall agreement: 0.874
proportions of specific agreement:
positive agreement: 0.381
negative agreement: 0.930 proportion of overall agreement: 0.903
proportions of specific agreement:
positive agreement: 0.444
negative agreement: 0.947 Analysis PA is relatively high compared to NA
presence of a significant number of FPs and FNs (9.7% for right eye; 12.6% for left eye)

small TP compared to TN

Chance aspect is attributed to the TPs, and FPs and FNs since better agreement between the two testers should have increased the TPs and TNs Null hypothesis: marginal proportion of pass/fail scores of teachers and optometrists are not different from each other

Right eye: p = 0.003; left eye: p = 0.000 (95%CI)

reject the null hypothesis

significant difference in the pass/fail scores of the testers The teachers and the optometrists do not seem to agree with each other . Null hypothesis: the diagnostic ability of the teacher to pass or fail the kindergarten student in terms of his/her visual acuity for either eye is independent of the diagnostic ability of the optometrist to accomplish the same task

Right eye: x^χ2 = 40.009, P = 0.000; left eye: x^2 = 42.106, P = 0.000
reject the null hypothesis The diagnostic ability of the teachers may be related and has a dependence on the optometrist’s ability to arrive at the same conclusion. Wilcoxon's Paired T-Test ICC Null hypothesis: the differences in the distribution of the VA scores of the optometrist and the teacher for either eye is zero, i.e., they are not different

right eye: Z = -4.934, P = 0.000; left eye: Z = -6.097, P = 0.000)
reject the null hypothesis The distribution of the VA scores gathered by the testers on either eye is significantly different. Null hypothesis: there is no significant difference between the means of the VA scores obtained by the testers

VA Scores
right eye: t = 5.236, p = 0.000
left eye: t = 6.641, p = 0.000
reject the null hypothesis There is a significant difference between the mean logMAR scores obtained by the testers. right eye: average measure ICC = 0.671 (P = 0.000, 95% CI = 0.567 – 0.750)

left eye: average measure ICC = 0.721 (P = 0.000, 95% CI = 0.633 – 0.788) The extent by which the scores of the testers agree with each other is strong. Workforce Procedures Dedicated team

Committed optometrists

Agreement and partnership Early testing

Dedicated day for testing

Predetermined batching scheme

Longer training for teachers Better relationships with stakeholders

Parent orientation

Standard portable light source

Farther location of test centers

Parent/Teacher/Guardian care

Sufficient school staff TP: true positive TN: true negative
FP: false positive FN: false negative Price: (50.00 USD ~ PHP2000)

Flipbooks in bulk and at a lower price


Reproduction of the test locally

Reduce the cost

Further testing

Post-diagnostic treatment Objective Significance Lay tester Optometrist Unable to find stable employment Poor performance in school Poor Vision Drop-out Health Reasons Vitamin A Deficiency Malnutrition Quezon City Cost-effective Lea Symbols Test Accessibility Defining Vision Refractive Errors Myopia Hyperopia Visual Impairment Worldwide 90% 19 million 285 million 10,226 optometrists 1573 opthalmologists 3.6 million School Drop-outs 360,000 students 750,000 students 2.16 million Bottom 20% Income group Non-attendance Elementary students Disability drop-outs Benefits of Early Detection Lower chances of improper placement Lower drop outs Easier time for teachers Removal of visual impairment disadvantage Philippine Preschools Republic Act 10157 Detection of vision disorders Preschool Visual Acuity Testing Primary Education
and Child Healthcare Evaluation of Past Studies and Interventions Testability factors of Lea Protocol Considerations Importance of Interventional Programs Crowding Features and Age-Specific Visual Acuity Tests (Vision in Preschoolers Study, 2004) Control test environment Lea test: higher testability 3-5 year olds: best subjects Crowding Features and Age-Specific Visual Acuity Tests (Repka, 2002) Testability increases with age Single symbol Lea works best Child Cooperation (Becker et al., 2002) Cooperation increases with age Lea Symbols is child appropriate (less than 30 months) Lea Symbols test is more effective Administration by Lay Testers (Schmidt, Baumritter, Ying, et al., 2005) Identical sensitivity for scores of nurse and lay screeners Screener and child fatigue as potential confounding factors Protocol Considerations: Testing Factors (Kvarnstrom and Jakobsson, 2005) occluder distance light Importance of Interventional Programs Addressing Visual Impairment Problems (Toledo, 2010) 25% of these students only had fair or poor academic performance 75% of students were visually impaired Strong agreement between the teachers and optometrists (ICC) Validation of hypothesis Lack of health workforce addressed Statistical differences in the visual acuity scores present a concern Recommendations to improve the study Further studies Methodology
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