Jyothi Thomas

Normative data for near point of convergence, accommodation, and phoria

Background: Measurement of for near point of convergence (NPC), amplitude of accommodation (AA) and phoria are important components of diagnosing nonstrabismic binocular vision anomalies. There is a huge variation in the normative data established for orthoptic parameters because of the variation in measurement technique. There are only limited studies for normative data based on nonclinical population in Indian population. Therefore, we aim estimate the normative values for NPC, AA, and phoria measurement in Indian population using techniques, which has good repeatability and reliability. Materials and Methods: Subjects between the age group 10-35 years participated in this prospective cross-sectional study. A self-administered symptom questionnaire was used to exclude patients with asthenopic symptoms. Clinical techniques which have good repeatability and reliability were used. NPC was measured using pen light red, green glass test. AA was measured using minus lens technique. Horizontal and vertical phoria at distance and near was measured using modified Thorington method. Results: One hundred and fifty subjects participated in the study. We found that NPC receded with age, which could because of the increase in horizontal phoria at near with age. The mean normative value for objective NPC, break and recovery of subjective NPC, monocular and binocular AA, horizontal and vertical phoria at distance and near for the three age groups are reported in the study. Conclusion: The data presented in this study can be used as a cut-off by eye care practitioners while diagnosing convergence, accommodation related anomalies in Indian population.

The effect of smoking on the ocular surface and the precorneal tear film.

BACKGROUND Smoking, both active and passive, creates a plethora of health-related problems, which primarily affect the cardiovascular and respiratory systems. There is very little evidence on the effects of tobacco smoke on the eye, especially regarding anterior ocular surface related pathology. This study was undertaken to determine the effects of smoking on the ocular surface and the tear film in smokers. METHODS A total of 51 (102 eyes) smokers and 50 (100 eyes) age-and gender-matched healthy non-smokers were included in this study. The ocular surface was evaluated by measuring tear film break-up time, surface staining with fluorescein, and corneal and conjunctival sensitivities, and by completing the Schirmers II test. Data was analysed using Statistical Package for Social Sciences (SPSS) version 11.5. A p value less than 0.05 was considered statistically significant. RESULTS The smoker group had significantly lower tear film break-up time, and corneal and conjunctival sensitivity than the nonsmoker group. Punctate staining was significantly higher in the smoker group than the non-smoker group. There was no statistically significant difference in Schirmers II test results between the smoker and non-smoker group. CONCLUSION Smoking caused adverse effects on the precorneal tear film and there was strong association between smoking and tear film instability. Although a causative relationship could not be determined, there is a need for further longitudinal studies.

Reliability of a modified logMAR distant visual acuity chart for routine clinical use

Background/Aim: Acuity charts that follow the principle of logarithmic size progression (logMAR charts) are considered to be the gold standard for the assessment of distant vision. But it is not well accepted for routine eye examinations due to increased testing time and the complexity of scoring. This study was designed to check whether a modified logMAR chart with three optotypes would provide a reliable acuity assessment compared to standard logMAR charts for routine eye examination. Materials and Methods: Two versions of modified and standard logMAR charts were designed, constructed, and used to assess the visual acuity of 50 individuals drawn from a typical out-patient population. Timed test-retest variability and limit of agreement (95% confidence limit of agreement) of the modified chart are compared to the standard logMAR chart using Bland-Altman method. A comparison of the testing time was carried out using paired t-test. Results: The test-retest variability of the charts was comparable, with 95% confidence limit of the mean difference being ±0.08 for standard logMAR and ±0.10 for modified logMAR. Both the versions of modified logMAR charts produced the results which agreed well with those of the standard logMAR charts. The mean testing time required to complete the acuity measurements with the modified chart was significantly lesser compared to the standard chart (P < 0.001). Conclusion: The outcomes of the current study demonstrates that the modified logMAR chart with three optotypes offers a comparable result to the standard logMAR charts for assessing distant visual acuity in routine clinical examination set up with a much lesser testing time.

Test Re-Test Reliability and Validity of Different Visual Acuity and Stereoacuity Charts Used in Preschool Children

BACKGROUND Preschool vision screenings are cost effective ways to detect children with vision impairments. The use of any vision tests in children must be age appropriate, testable, repeatable and valid. AIM To compare the test re-test reliability, sensitivity and specificity of different visual acuity and stereo acuity charts used in preschool children. MATERIALS AND METHODS Monocular visual acuity of 90 subjects (180 eyes) of age 36 to 71 months was assessed with HOTV, Lea and E-chart in a preschool located in a semi urban area, Manipal, Karnataka. After the vision assessment, stereo acuity was recorded using Frisby and Titmus stereo charts followed by comprehensive eye examination. Repeated measurements of visual acuity and stereo acuity were done one week after the initial assessment. RESULTS Mean age of children was 53± 10 months with equal gender distribution. Intra class correlation (ICC) of Lea, HOTV, E-chart, Frisby and Titmus charts were 0.96, 0.99, 0.92, 1.0 and 1.0 respectively. The area under receiver operating curve (ROC) for Lea and E-chart was 0.892 and 0.776. HOTV was considered as the gold standard as it showed the least difference on repeated measurements. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of E-chart was 99, 15, 45, 94 and 21.8 percent, and Lea was 93, 56, 59 and 92 percent. The sensitivity, specificity, PPV and NPV of Frisby was 75, 27, 9, 92 percent were as of Titmus was 75, 13, 8 and 85 percent respectively. CONCLUSION HOTV chart can be used as the gold standard for measuring visual acuity of pre-schoolers in a semi urban area. Lea chart can be used in the absence of HOTV chart. Frisby and Titmus charts are good screening tools, but with poor diagnostic criteria.

Contact lens compliance among a group of young, university-based lens users in South India

PURPOSE To investigate the rate of compliance with the soft contact lens care and maintenance procedures with a focus on contact lens wearing habits, cleaning and disinfecting procedures, and maintenance of lens care accessories in a group of young, university-based contact lens wearers METHODS Two hundred and sixteen young soft contact lens wearers with an age range of 18-22 years were selected conveniently from the student population of Manipal University, Manipal, India. After receiving informed consent from the participants, their level of compliance with contact lenses was assessed using a questionnaire. RESULTS The mean (±SD) age of the participants was 21.86±2.35 years. Out of 216 subjects, only 34% of the lens users were identified to be compliant with the least level of compliance observed in the maintenance of lens care accessories. Conventional users showed significantly (p=0.001) better level of compliance compared to disposable wearers and so did the users who acquired their lenses from clinicians (p=0.001) compared to over-the-counter lens receipt. The gender (p=0.496) and years of experience in contact lens use (p=0.142) did not show any statistically significant difference in the level of compliance. CONCLUSION This study demonstrated that non-compliance with lens care procedures among a group of young, university-based soft contact lens wearers is common. The results indicated that all subjects had some degree of non-compliance and the least level of compliance observed in the care of lens accessories.

Awareness, knowledge, and barriers to low vision services among eye care practitioners

Background: Eyesight plays an important role in our day today life. When the vision gets hampered, daily activities of an individual will be affected. The prevalence of visual impairment is increasing across the globe, with more burdens on the developing world. The uptake of low vision services remains to be low in developing countries like India. Methods: A newly constructed questionnaire using information from previously conducted telephonic interviews and article search was administered among 50 eye care practitioners from Kerala, India for the pilot study. Modifications were made in the questionnaire, based on the responses obtained from the pilot study. From their responses, awareness, knowledge, and barriers for the low vision services among eye care practitioners were assessed. Results: (1) Pilot study - the Cronbach′s alpha values obtained for knowledge, awareness and barrier questions were 0.814, 0.297, and 0.810, respectively, and content validity index was found to be 0.64. (2) Main study - 211 eye care practitioners from 12 states of India took part in the study that accounted for a response rate of 16.7%. The participants included were 95 (45%) men and 116 (55%) women with a mean age of 28.18 ± 7.04 years. The lack of awareness was found to be the major barrier in the provision and uptake of low vision services from the practitioner′s perspective. Conclusion: The study results showed that there is a lack of awareness among eye care practitioners about low vision services, which acts as a major barrier in the effective delivery of these services.

Ocular Morbidity among 3 to 6 Year Old Children Visiting a Tertiary Care Hospital: A Prospective Study

Introduction: Preschool children are reported to have visual deficits ranging from 5 to 29% . Children are unable to understand their symptoms, communicate it, hence early detection and intervention remains a challenge. Usually there is no manifestation of the visual disorder and are unheeded. Purpose: To determine the ocular morbidity among 3 to 6 year old children visiting a tertiary care hospital. Method and procedures : Ethical Committee approval was obtained. Children with developmental delay, non co-operation and parental reluctance were exclusion criteria for the study. Each child was assessed with E chart for vision, stereo acuity measurement with randot preschool, dry refraction, anterior and posterior segment evaluation and cycloplegic refraction. Descriptive statistics and chi square tests were employed for statistical analysis. Results: Two hundred eyes (100 participants) were analyzed. 52% were boys and 48% girls. Mean age was 64.6± 12.3 months. Refractive error was observed in 80 eyes(40%) ,45 eyes(22.5%) had amblyopia, anterior segment disorders were noted in 24 eyes (12%) and squint observed in 5 eyes(2.5%). Conclusion: Refractive error, amblyopia, anterior segment disorders, squint and posterior segment pathology were the ocular morbidity found in 3 to 6 year old children.

Validity of different screening tests for detecting visual impairment in 3 to 6 year old children

Background: Preschool vision screenings (PVS) are recommended for early detection and treatment of childhood visual disorders. At present, the vision screening protocols in childhood varies from country to country and even within countries Objective: To determine the sensitivity and specificity of different screening tests used for visual impairment detection in the 3 to 6 year old children Method : Ethical Committee approval and parental consent obtained. Each child was assessed with Lea symbol and E charts for vision, stereo acuity measurement with Randot preschool stereo test, photo refraction by Plus optix A09, cover tests, cycloplegic refraction and retinal evaluation. Visual impairment (VI) was defined as presenting visual acuity in better eye <6/12. Receiver Operating Characteristics Curve (ROC) was used for statistical analysis. Results: A total of 200 eyes (100 participants) were analysed. 52% were males and 48% females.49.5% had visual impairment. The sensitivity and specificity of Lea symbol chart, Randot preschool and Plus optix A09 (spherical and cylindrical values) for detecting visual impairment were 91.8%, 56.2%, 51.8% ,81.8% and specificity were 91.9%,83.3%,50% , 68% respectively . Conclusion: Lea symbol chart had high sensitivity to pick up visual impairment in 3 to 6 year old children.