Krithica Srinivasan

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.

Efficacy of a remote based computerised visual acuity measurement

Aim To determine the efficacy of a remotely operated computer-based logarithmic (logMAR) visual acuity chart. Methods Visual acuity was tested using a laptop or computer-based logMAR chart (COMPlog) for all subjects by two different methods. The methods differed by the physical presence and absence (remote) of an optometrist and in the mode of instructions provided. Remote access was obtained through the internet, using Teamviewer software to control the system linked to COMPlog and instructions were provided by telephone. The order of measurements and the eye to be tested was randomised. logMAR visual acuity and time taken were recorded. A questionnaire was used to assess the participants feedback. Results Intraclass correlation for visual acuity between the two methods (α=0.964, 95% CI 0.937 to 0.979). There was no statistically significant difference (p=0.648) in the median visual acuity measurement between the two methods (median difference 0.00, IQR 0.20 logMAR). The time taken between the two methods was not statistically significant (p=0.457). There was no significant difference in the responses to the questionnaire between the study methods (p=0.119). Conclusions Tele (remotely controlled) visual acuity measurement is as reliable as that measured with the physical presence of an optometrist.

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.

Development of Pocket Vision Screener and its effectiveness at screening visual acuity deficits

Aim: The aim was to construct a visual acuity chart and find its effectiveness at screening visual acuity deficits. Materials and Methods: Two phases were involved in this study. Construction of the screener: Ten Sloan letters (C, D, H, K, N, O, R, S, V, and Z) were selected and the letters were constructed and reduced to 0.2 logMAR acuity size (6.92 mm) for viewing at 3 m. The screener contains three lines with seven letters in each. Few combinations of the seven letter sequences were chosen based on the row legibility scores. Three seven letter combinations close to the median of all combinations were selected, such that maximum difficulty score difference between the lines are <1%. Finding the effectiveness of the screener: 100 literate subjects with unaided visual acuity better than or equal to 6/60 were recruited for the study. Unaided visual acuity was tested using both the newly constructed Pocket Vision Screener and a logMAR visual acuity chart and the time taken to measure the visual acuity using both the charts was noted. Results: The mean age of the subjects was 43 ± 17 years. Subjects were classified as normal or deficient based on the logMAR visual acuity measurement. The screener was found to have 81% sensitivity, 94% specificity. The positive and negative predictive values were found to be 91% and 87%, respectively. A significant difference (P < 0.001) was found in the time taken to record visual acuity using both the charts. Conclusion: The Pocket Vision Screener can be used as a quick and accurate tool to screen subjects for visual acuity deficits, being highly sensitive, specific, and cost-effective.

3-(3,4-Dimeth-oxy-benz-yl)chroman-4-one.

In the title compound, C18H18O4, the six-membered chroman-4-one ring adopts an envelope conformation with the C atom bonded to the bridging CH2 atom as the flap. The dihedral angle between the mean plane of the fused pyranone ring and the dimethoxy-substituted benzene ring is 89.72 (2)°. In the crystal, adjacent molecules are linked via C—H⋯π interactions.

rac-3-(4-Hy-droxy-benz-yl)chroman-4-one.

In the racemic title compound, C16H14O3, the ring of the 4-hydroxybenzyl substituent group forms a dihedral angle of 80.12 (12)° with the benzene ring of the chromanone system. Two C atoms of the pyranone ring and the H atoms on the benzyl α-C atom are disordered over two sites, with site-occupation factors of 0.818 (8) and 0.182 (8). The crystal structure is stabilized by O—H⋯O hydrogen bonds, which form parallel one-dimensional zigzag chains down the c axis and are interconnected by both methine C—H⋯O hydrogen bonds and weak aromatic C—H⋯π interactions, giving a sheet structure lying parallel to [011].

Reliability and validity of a Kannada rate of reading test

Purpose: Kannada, one of the Dravidian languages, is the official language of Karnataka state of India. There is a need for a test using Kannada words that can assess visual aspects of reading independently of syntactic and semantic knowledge. Methods: A test of reading rate in Kannada was developed following the design principles of the Wilkins Rate of Reading Test (RRT). Fifteen high-frequency bisyllabic Kannada words were selected. Children were recruited from state and private schools that used Kannada or English as the medium of instruction. A total of 799 children from Grade 2 to 9 participated in the study. Reading rate was measured using the English RRT and the Kannada version twice in immediate succession during the first session. In 85 children, measurements using the Kannada RRT were repeated after an interval of 15 days. Results: Pearson product moment correlation between the two immediately successive tests was 0.95 for the Kannada RRT and 0.91 for the English RRT. The correlation for the tests separated by an interval of 15 days was 0.83. When Kannada was the medium of instruction, there was little difference between test scores for Kannada and English. When English was the medium of instruction, test scores were greater in English. Scores increased as expected with age (P < 0.0001), similarly for Kannada and English tests. Conclusion: The newly developed Kannada RRT is both reliable and valid and can be used as a tool for measuring the visual aspects of reading.

Synthesis, anticancer, structural, and computational docking studies of 3-benzylchroman-4-one derivatives

A series of 3-Benzylchroman-4-ones were synthesized and screened for anticancer activity by MTT assay. The compounds were evaluated against two cancerous cell lines BT549 (human breast carcinoma), HeLa (human cervical carcinoma), and one noncancerous cell line vero (normal kidney epithelial cells). 3b was found to be the most active molecule against BT549 cells (IC50 = 20.1 µM) and 3h against HeLa cells (IC50 = 20.45 µM). 3b also exhibited moderate activity against HeLa cells (IC50 = 42.8 µM). The molecular structures of 3h and 3i were solved by single crystal X-ray crystallographic technique. Additionally, the molecular docking studies between the tumour suppressor protein p53 with the lead compound 3h, which exhibited better anticancer activity against HeLa cells was examined.