Discrimination of paediatric acuity test optotypes by 6-year-old children.

PURPOSE: To compare the discrimination performance of 6-year-old children for optotypes from six paediatric visual acuity tests and to fit Luce's Biased Choice Model to the data to estimate the relative similarities and bias for each optotype. METHODS: Full data sets were collected from 20 typically developing 6-year-olds who had passed a vision screening. They were presented with single optotypes labelled 6/12 at a distance of 9 m and were asked to identify the optotype using a matching task containing all optotypes from the relevant test. The data were combined to form a confusion matrix for each test and a biased choice model was fitted to the data. RESULTS: Median correct performance varied from 40% to 100% across optotypes, with the HOTV test having the highest values. Estimates of the similarity of each pair of optotypes indicated equal values for all pairs in the Landolt C, HOTV, Lea numbers and Tumbling E tests. The values differed for the picture tests, that is Lea Symbols and Allen figures. The estimates of bias for each individual optotype also indicated different values with the picture tests. CONCLUSIONS: Previous studies of the threshold acuity of young children and adults have indicated differences in acuity estimates across paediatric tests. A recognition acuity task typically requires resolving the difference information between optotypes. The performance of the 6-year-olds here reveals variance in similarity and bias values for picture tests, particularly for the Allen figures when compared with the Lea Symbols. Ideally, this analysis should be performed when designing new tests, and these results motivate progression from the use of current picture tests to well calibrated letter or number tests at the earliest possible age.

Visual profile of acquired brain injury in Indian cohort: a retrospective study.

OBJECTIVE: With the increasing global prevalence of acquired brain injury (ABI), the burden of visual problems as a sequelae to ABI is on the rise. This study reports the visual profile of patients with ABI seen in Neuro-Optometry Clinic (NOC) at a tertiary eye-care center in Southern India. METHODS: A retrospective study was carried out between January 2014 and December 2015. Medical records of patients diagnosed with ABI referred by Neuro-Ophthalmologists to the NOC were reviewed. The detailed history, clinical findings of neuro assessment and management details were recorded. RESULTS: Of the 241 patients with ABI, 208 had Traumatic Brain Injury (TBI) and 33 had Cerebro-Vascular Accident (CVA). The mean (SD) age of patients with TBI was 35 ± 14 years and CVA was 52 ± 16 years. Binocular diplopia (61%) was seen predominantly in TBI due to vertical deviation (31%). Cranial nerve palsy was most common in TBI (55%) than CVA (36%) and visual field defects were most frequently seen in CVA (27%). CONCLUSION: Cranial nerve paresis and restrictive strabismus with diplopia were the most common presentations in TBI and visual field defects in CVA. A neuro-optometric evaluation is recommended to identify visual dysfunctions and provide appropriate management options. ABBREVIATIONS: ABI: Acquired Brain Injury; TBI: Traumatic Brain Injury; CVA: Cerebrovascular Accident; NOC: Neuro-Optometry Clinic; NSBVA: Non-Strabismic binocular vision anomalies; OMD: Oculomotor dysfunction; VFD: Visual field defect; GON: Glaucomatous optic neuropathy.

Actomyosin organelle functions of SPIRE actin nucleators precede animal evolution.

An important question in cell biology is how cytoskeletal proteins evolved and drove the development of novel structures and functions. Here we address the origin of SPIRE actin nucleators. Mammalian SPIREs work with RAB GTPases, formin (FMN)-subgroup actin assembly proteins and class-5 myosin (MYO5) motors to transport organelles along actin filaments towards the cell membrane. However, the origin and extent of functional conservation of SPIRE among species is unknown. Our sequence searches show that SPIRE exist throughout holozoans (animals and their closest single-celled relatives), but not other eukaryotes. SPIRE from unicellular holozoans (choanoflagellate), interacts with RAB, FMN and MYO5 proteins, nucleates actin filaments and complements mammalian SPIRE function in organelle transport. Meanwhile SPIRE and MYO5 proteins colocalise to organelles in Salpingoeca rosetta choanoflagellates. Based on these observations we propose that SPIRE originated in unicellular ancestors of animals providing an actin-myosin driven exocytic transport mechanism that may have contributed to the evolution of complex multicellular animals.