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Ophthalmic nursing procedures and investigations
Published in Mary E. Shaw, Agnes Lee, Ophthalmic Nursing, 2018
The LogMAR chart was designed by Bailie and Lovie and was originally used in the Early Treatment Diabetic Retinopathy Study. The LogMAR chart (Figure 3.2) is expressed as the logarithm of the minimum angle of resolution. LogMAR scale converts the geometric sequence of a traditional chart to a linear scale. It measures visual acuity loss so that positive values indicate vision loss, while negative values denote better or normal vision. It is therefore more accurate than the Snellen’s chart and it is gaining more popularity clinically. The chart is designed to be used at various distances such as 4, 3 or 2 m. Unlike the Snellen chart which has 11 lines of block letters and subsequent rows of increasing numbers of letters in decreasing size, the LogMAR uses a special font in which all the lines are of equal thickness and the letter size increases in equal steps of 0.1 LogMAR per line. Bailey and Lovie also advocated that the visual acuity test chart should essentially be the same at each size level on the chart, so that there are the same number of letters on each line and the task of testing for visual acuity is equivalent for each line. The LogMAR chart has five letters of ‘almost equal legibility’ on each of the rows. Spacing between letters on each row is equal to one letter width, and spacing between rows is equal to the height of the letters on the smaller row. The LogMAR chart thus uses letters of equal legibility, the same number of letters in each row and uniform between-letter and between-row spacing to overcome some of the limitations of the Snellen’s chart in which the letters are fairly large and in which there are uneven jumps in the acuity level between the rows. In addition, the crowding of letters on the Snellen’s chart also inherently makes it more difficult to read.
Unilateral Vision Loss in Elderly People in Residential Care: Prevalence, Causes and Impact on Visual Functioning: The Hyderabad Ocular Morbidity in Elderly Study (HOMES)
Published in Ophthalmic Epidemiology, 2023
Srinivas Marmamula, Navya Rekha Barrenkala, Thirupathi Reddy Kumbham, Satya Brahmanandam Modepalli, Jill Keeffe
Trained examiners conducted the clinical assessments in ‘makeshift’ (temporary) clinics set up in each home for the aged. The clinical assessment protocol has been described in our previous publications.23,24 In brief, the clinical examination included visual acuity assessment, refraction, anterior and posterior segment examination. Distance and near visual acuity (VA) were assessed using a logMAR chart (logarithm of Minimum Angle of Resolution) at three metres and 40 centimetres, respectively. Tumbling E chart and English charts were used as needed. Also, presenting, pinhole, and best-corrected visual acuity were assessed. Anterior segment examination was done using a portable handheld slit lamp biomicroscope (BA 904 Haag-Streit Clement Clarke International, UK). Fundus images were taken using a non-mydriatic fundus camera (Zeiss Visuscout 100), and they were graded by trained graders. Participants having VI due to uncorrected refractive errors were provided with spectacles, and those who needed further care were referred to the L V Prasad Eye Institute for service provision. All eye care services and spectacles were provided at no cost to the participants.
Effectiveness of visual and acoustic biofeedback eccentric viewing training in conjunction with home exercises on visual function: a retrospective observational review
Published in Strabismus, 2023
Natalia Kelly, Meri Vukicevic, Konstandina Koklanis
The patient’s visual function was measured at baseline, at the conclusion of the program and one-month post-treatment. The baseline measures were assessed with the patient’s PRL as the TRL was yet to be determined. The TRL was employed to assess the outcomes measures at the conclusion of treatment and one-month post-treatment. Visual function included best corrected visual acuity (VA) with both eyes open (distance and near), contrast sensitivity and fixation stability. Patients wore their most recent habitual prescription to assess acuity and contrast. Distance visual acuity was assessed with the Early Treatment Diabetic Retinopathy Study (ETDRS) chart, and the logMAR unit of measure was used to document the outcome. Near visual acuity was assessed using the Near Logarithm of the Minimum Angle of Resolution (LogMAR) chart, and the N-point notation was used to report near visual acuity. Contrast sensitivity was assessed by the Low Contrast Flip Chart 10 M Optotypes with Lea Symbols, and the number of symbols seen was recorded. Up to 5 symbols represented 25% contrast, 10 indicated 10% contrast, 15 was 5% contrast, 20 was 2.5% contrast and up to 25 symbols indicated 1.25% contrast.
Non–absorbable versus Absorbable Sutures for Medial Rectus Advancement in Consecutive Exotropia, a Pilot Randomized Clinical Trial
Published in Journal of Binocular Vision and Ocular Motility, 2022
Mohammad Reza Akbari, Amirreza Veisi, Arash Mirmohammadsadeghi
All patients underwent complete ophthalmic examinations before surgery. Visual acuity was assessed using a logMAR chart at a distance of 6 m. Significant refractive errors were corrected according to manifest refraction in adult and cycloplegic refraction in pediatric patients. The angle of deviation was measured after the correction of significant refractive errors. Amblyopia was assumed when the difference of the best-corrected visual acuity between two eyes was more than 2 lines or the vision was less than 20/40 bilaterally. Distance (at 6 m) and near (at 33 cm) deviations were measured by prism and alternate cover test. In the cases with low vision in one eye, the deviations were measured with Krimsky test.The angle of deviation was measured in two sessions preoperatively by a masked examiner. Ductions were graded from 0 (full duction) to −4 (unable to abduct past the midline). Forced duction test (FDT) was performed under general anesthesia for detection of lateral rectus contracture. The patients with LR contracture (positive FDT) were excluded from the study.