Saturday, November 19, 2016: For those of us who have seen an optometrist/ophthalmologist I'm sure you remember being asked to read a series of letters, that decrease in size, through your right (OD - oculus dexter) and left (OS - oculus sinister) eye, respectively, and through a series of corrective lenses. These letters would have been read off either a Snellen chart or a LogMAR chart, and this procedure is to test your visual acuity. However, for our Jiri Eye Study, visual acuity is tested using a tumbling E chart which is used in countries, like Nepal, where the language is not derived from the Latin alphabet. A common cause of low visual acuity - less than 6/6 (20/20) vision - is some degree of refractive error; common refractive errors include myopia (near-sightedness), hyperopia (far-sightedness), presbyopia [I've been a 'member' of this group for a few years now], and astigmatism.
Here we see Tika Rai ji, from the Tilganga Institute of Ophthalmology, asking a female research participant to state in which direction (up, down, right, left) the limbs of the 'E' are pointing. The eye chart being used is a LogMAR tumbling E chart.
Here we see Tika Rai ji, from the Tilganga Institute of Ophthalmology, asking a female research participant to state in which direction (up, down, right, left) the limbs of the 'E' are pointing. The eye chart being used is a LogMAR tumbling E chart.
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The LogMAR tumbling E chart is used to assess distance vision. To assess near vision visual acuity, near vision test cards are used. The JES near vision test cards are depicted below. Note that the test cards include both textual and pictorial content; the pictorial content is for those individuals who are illiterate.
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Tika Rai ji also conducts an A-scan ultrasound biometric assessment of the research participants eyes (OU - oculus uterque). Here she measures the depth of the anterior chamber, axial length, and lens thickness. These quantitative dimensional properties of the eye are important factors in determining the severity of refractive error and intraocular lens (IOL) power calculations.
Here we see Tika Rai ji applying the A-scan probe to a female research participant's eye. The probe emits a sound beam at a frequency of approximately 10 million hertz (10 MHz) to record ocular biometry. The image on the right displays the axial length (in millimeters - mm).
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Today's menu...
Breakfast: Masala omelet with toast and jam (jelly)
...Followed by a bean and potato chaser.
Lunch: Achaar, cauliflower, rice, black-eyed peas, saag, and dhal
Dinner: Snacks (I'll promise to take pictures of our dinner snacks and post them over the next few days)
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