Mahesh Raj Joshi

Mahesh Raj Joshi
University of Plymouth | UoP · School of Health Professions

PhD

About

28
Publications
5,491
Reads
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151
Citations
Additional affiliations
September 2018 - present
University of Plymouth
Position
  • Lecturer
March 2017 - August 2018
University of the West Indies, St. Augustine
Position
  • Lecturer
June 2016 - December 2016
Glasgow Caledonian University
Position
  • PostDoc Position
Description
  • Worked on a clinical trial exploring perceptual learning treatment methods in amblyopia.
Education
November 2012 - December 2016
Glasgow Caledonian University
Field of study
  • Visual Neuroscience
January 2010 - December 2011
University of South-Eastern Norway
Field of study
  • Optometry and Vision Science
December 1999 - December 2002
Tribhuvan University
Field of study
  • Optometry

Publications

Publications (28)
Article
Sloan letters are one of the most commonly used optotypes in clinical practice. Sloan letters have different relative legibility which could be due to three factors: perceivability, response bias, and similarity. Similarities between Sloan letters are known to be the major source of errors in threshold determination. However, little is known about...
Poster
Full-text available
In clinical testing of visual acuity and contrast sensitivity, it is often assumed that data reflect sensory performance and observers do not exhibit strong biases for or against specific letters, but this assumption has not been extensively tested. We measured letter identification performance against letter size, spanning the resolution threshold...
Article
Global motion and global form are proposed to be processed through functionally differentiated independent channels along dorsal (motion) and ventral (form) pathways. However, more recent studies show significant interactions between these pathways by inducing the perception of motion (implied motion) from presenting the independent frames of stati...
Article
Aim To determine if a gradual adaptation period is necessary for neophytes when fitted with modern hydrogel or silicone hydrogel reusable disposable contact lenses. Method Across four sites, 74 neophytes (18–28 years) were randomly assigned to a reusable lens cleaned nightly with Opti-Free® Puremoist® multi-purpose contact lens solution: Proclear®...
Article
Optometry education in Nepal began in 1998 in collaboration with the University of Auckland, New Zealand, with the primary objective of addressing the unmet needs of eye health and vision care. Over the last two decades, the development of optometry education has seen significant progress, including a shift from a three-year to a four-year curricul...
Article
Full-text available
Purpose To determine the causes of visual impairment and the use of low vision devices in patients attending the low vision clinic in Trinidad and Tobago. Methods A retrospective study of the 222 patients attending the low vision clinic at the University of the West Indies, St Augustine Campus was conducted. The presenting visual acuity, causes of...
Preprint
Full-text available
Purpose Letter resolution depends on three factors: perceivability, response bias, and similarity. The aim of the present study was to investigate the effect of response bias (the sensory-independent factor) on resolution thresholds of Sloan letters in central and paracentral vision. Methods Nine subjects with normal ocular health were recruited f...
Article
Full-text available
Purpose: Global motion and global form perception have been found to be abnormal in the presence of amblyopia. How such deficits manifest in visual function reliant on the interactions between these two visual processing mechanisms has not been adequately explored. In the current study, we use dynamic Glass patterns (dGlass) to measure implied mot...
Article
Purpose To establish the optimum grading increment which ensured parity between practitioners while maximising clinical precision. Methods Second year optometry students (n = 127, 19.5 ± 1.4 years, 55 % female) and qualified eye care practitioners (n = 61, 40.2 ± 14.8 years, 52 % female) had 30 s to grade each of bulbar, limbal and palpebral hyper...
Conference Paper
Full-text available
Glass patterns with varying elements and line segments have been used to investigate global form processing. However, if these different stimuli target similar local or global form processing mechanism is not known. A total of 5 visually normal participants discriminated orientation of Glass patterns composed of different component element (2 eleme...
Conference Paper
Purpose: To quantitatively measure the perceptual distortion experienced by individuals with keratoconus and correlate the magnitude of distortion with corneal structural measurements. Methods: A total of 25 adults (mean age = 29.84 ± 7.46 years) with keratoconus underwent measurements of visual and refractive status, corneal topography, and centr...
Conference Paper
Global motion and global form perception is known to be abnormal in amblyopia. However, how such deficits manifest in the visual function thought to be reliant on the interactions between the two processing mechanisms, such as the perception of implied motion, is yet to be explored. A total of 13 amblyopes (8 strabismic and 5 anisometropic) and 6 n...
Article
Full-text available
Purpose: Directly comparing the motion and form processing in neurologic disorders has remained difficult due to the limitations in the experimental stimulus. In the current study, motion and form processing in amblyopia was characterized using random dot stimuli in different noise levels to parse out the effect of local and global processing on m...
Article
Motion and form processing along the functionally differentiated dorsal and ventral stream is reported to be abnormal in amblyopia; however limitations in previous stimuli have made analogous comparison of the outputs from these two streams difficult. In the current study, we characterise both functions in amblyopia using equivalent stimuli for fin...
Conference Paper
Abnormal motion and form processing along the dorsal or ventral pathway has been reported in amblyopia. In the current study, we attempted to characterise visual processings in both pathways in amblyopia concurrently using equivalent stimuli in the presence of noise. Six anisometropes, six strabismics, and 12 visually normal observers monocularly d...
Article
Full-text available
Background: Usher syndrome is a rare autosomal recessive disorder characterized by congenital sensory neural deafness and progressive visual loss secondary to retinitis pigmentosa. There are three different types of Usher syndrome. Retinitis pigmentosa is the main ophthalmic manifestation shared by all three. Differences in auditory and vestibular...
Article
Full-text available
The development of sensitivity to radial optic flow discrimination was investigated by measuring motion coherence thresholds (MCTs) in school-aged children at two speeds. A total of 119 child observers aged 6-16 years and 24 young adult observers (23.66 +/-2.74 years) participated. In a 2AFC task observers identified the direction of motion of a fi...
Article
Full-text available
Background: To evaluate peripapillary retinal nerve fiber layer (RNFL) thickness in glaucomatous Nepalese eyes using spectral domain optical coherence tomography (SD-OCT) and study its relationship with visual field sensitivity. Methods: A total of 120 eyes comprising primary open angle glaucoma (POAG), glaucoma suspects (GS), normal tension gla...
Article
Full-text available
The visual system is functionally differentiated into dorsal (motion) and ventral (form) pathways, owing to the limitations in previously employed stimuli analogous comparison of the outputs from these two streams has proven difficult. In the current study, we adapted the equivalent noise paradigm to (1) disentangle the effect of local and global l...
Conference Paper
The visual system is functionally differentiated into dorsal (motion) and ventral (form) pathways, owing to the limitations in previously employed stimuli analogous comparison of the outputs from these two streams has proven difficult. In the current study, we adapted the equivalent noise paradigm to (1) disentangle the effect of local and global l...
Conference Paper
Full-text available
Current study evaluated the sensitivity to global motion and form perception which are presumably processed by two distinct visual pathways – dorsal and ventral respectively [Ungerleider and Mishikin, 1982, in: Analysis of Visual Behavior, Cambridge, MIT press] – in varying noise levels. We used Glass pattern [Glass, 1969, Nature, 223, 578-579] and...
Conference Paper
The development of sensitivity to optic flow patterns was investigated by measuring motion coherence thresholds (MCTs) in school-aged children in Kathmandu. 119 child observers aged 6-16 years and 24 adult observers (mean age, 23.66 years) participated with informed consent. The observers identified the direction of a translational (rightward vs le...
Thesis
Full-text available
Introduction: Global motion processing is an essential part of visual perception involving higher cortical areas. The motion coherence threshold (MCT) is used to evaluate global motion processing. Previous studies have investigated the development of translational optic flow processing in children but no study has yet evaluated MCT for radial op...
Article
Full-text available
Introduction: Children from the developing world are more prone to going blind from avoidable and preventable causes. In Nepal, children in private schools are reported to have a higher ocular morbidity than those in government schools, with myopia being the major cause of the morbidity. This study was designed to evaluate ocular morbidity in stud...
Article
Full-text available
Color vision defect can be observed in various diseases of optic nerve and retina and also a significant number of people suffer from the inherited condition of red and green color defect. A cross-sectional descriptive study was designed with purposive sampling of students from various schools of Kathmandu Valley. All children were subjected to col...
Article
Full-text available
This study was carried out with the objective of finding refractive status of patients undergoing phacoemulsification surgery for cataract extraction. Success of cataract surgery can be quantified with the improvement in visual acuity with least amount of refractive error. Prospective study of 44 patients was done pre operatively and with subsequen...
Article
Full-text available
In Nepal, children with low vision attend specialized schools for students who are totally blind and are treated as if they were totally blind. This study identified children with low vision and provided low vision devices to them. Of the 22% of the students in the school who had low vision, 78.5% benefited from the devices. Proper devices and coun...
Article
Full-text available
A prospective cross sectional study of students of two private schools was done and students were screened in detail. A total of 1816 students aged 5 to 16 years were evaluated, out of which 52.8% were males and 47.2 % were females. Among the total, 65.8% had no ocular abnormalities and 34.2% had some form of ocular disorders. Refractive error was...

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Projects

Projects (4)
Project
Global motion and form is reported to be affected in various developmental and neurological disorders. In this study, we will evaluate how sensitivity to global motion and form is affected in patients who have compression in early areas of visual pathway caused by pituitary adenomas.
Project
The aim of the project is to asses perceptual distortion experienced by patients with keratoconus using psychophysical methods before and after visual correction.