Visual System Examination. Dr Mahmood Fauzi Ansari MBBS MS FCLI Asst. Professor Ophthalmology Al Mareefa college of medicine 2013-14. Eyes are the window to the brain!. Before Visusal exam----WIPE. Wash hand Introduce self Patient name DOB
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Dr Mahmood Fauzi Ansari MBBS MS FCLI
Asst. Professor Ophthalmology
Al Mareefa college of medicine
Optic axis—The line passing through the centre of curvature of cornea and the two surfaces of the lens, meets the retina at fovea centralis.
Nodal point—The optical centre lies in the posterior part of the lens.
Anterior focal distance—It is about 15 mm in front of the cornea.
Posterior focal distance—It is about 24 mm behind the cornea.
The average power of a normal emmetropic eye is + 58 to + 60D.
Most emmetropic eyes are approximately 24 mm in length.
Visual Acuity Grading (10th Revision of the WHO International Statistical Classification of Diseases).
1Good vision = 6/6 to 6/18.
2 Low vision = 6/24 to 3/60 (CF3m).
3Blind = 3/60 (CF3m) to PL (perception of light).
4Blind to light - NPL (no perception of light).
Near Vision Charts
-Reduced Snellen Acuity card Test distance at 14 inch (or 40cm)
-Jaeger Acuity Card
100 cm at age 70 yrs
50 cm at the age of 50 yrs
ON THE RETINA
BEHIND THE RETINA
INFRONT OR BEFORE RETINA
Convex lens or plus lens
Concave or minus lens
Convex cylinder Concave cylinder
Hypermetropic eye Correction with convex lens
-Red color blindness (protanopia)
-Green color blindness (deyteranopia)
-Bluecolor blindness (tritanopia)
AKA Pupillary Light Reflex
Retina Optic nerve Optic chiasmaOptic tract Pretectal Nucleus Parasympathetic Occulomotor nucleus
Oculomotor Nerve Nerve to inferior obliqueCiliary ganglion Short ciliary nerve Sphincter pupillae and ciliaris muscle
CReflex abolished if afferent or efferent is damaged.
Hypothalamus (CNS control center for ANS)
Preganglionic Sympathetic Neurons in Thoracic Cord (T1-T2)
Superior Cervical Ganglion
(pre-ganglionic sympathetic)Pupillary Dilation(Mydriasis)
Decreased light to pupil
Strong emotional stimulus
Dilation of pupil
Shift in gaze from far to near. (contraction of pupil)
2. Three components:
Retina Optic nerve Optic chiasmaOptic tract Lateral Geniculate Nucleus Optic Radiation Primary Visual Cortex
-ParasympatheticOculomotorNuclei OculomotorNerve Ciliary ganglion Short ciliary nerve Sphincter pupillae and ciliaris muscle
Marcus-Gunn pupil—There is ill-sustained contraction of the pupil in swinging flashlight test, e.g. as in retrobulbar neuritis.
Argyll Robertson pupil: Pupillary constriction occurs as part of the accommodation reflex, but not in response to light.
Refraction of the light rays
Accommodation of the eyes to light
2. Amblyopiapartial loss of sight, fixation reflexes not developed.
3. Amaurosis complete loss of sight in one or both eyesLESIONS OF THE VISUAL PATHWAY
Strabismus, Proptosis, Ptosis, Sclera, Around eye stye, swelling, discharge etc)
Temporal Field of Left Eye
Lower Field of Left Eye
Upper Field of Left Eye
Nasal Field of Left Eye
Normal Monocular Visual Field of Left Eye
Normal Monocular Visual Field of Right EyeVisual Fields
Definition: The entire area that can be “seen” by the patient without movement of the head and with the eyes fixed on a single spot.
The optic chiasma
Charting of the visual fields is very useful in the diagnosis of many disease conditions
• Retinal diseases e.g. retinitis pigmentosa
• Follow up of laser treatment for diabetic retinopathy
• Neurological disorders, e.g. brain tumours, head injury, multiple sclerosis, cerebral thrombosis,
It consists of a half sphere within which a spot of light can be moved
Method—The patient is seated with his chin supported by the chin rest.
• One eye is covered by a pad.
• The other eye fixes an object placed at the centre of the arc.
• The field is recorded first with a white object 5 mm in
diameter from periphery to centre.
• At least 8 or preferably 16 meridians must be tested.
Automated perimeters, e.g. Friedmannanalyser, Ouplot, Auto field perimeters Field master and Humphery field analyser
Automated perimeters utilize computers to programme visual field sequences, e.g. Baylor visual field
programmer attached to standard Goldmann perimeter.
The changes induced by the stimulation of light in the resting potential of the eye are measured by electroretinography.
It is extinguished or absent in complete failure of function of rods and cones, e.g. pigmentaryretinal dystrophy, complete occlusion of retinal artery, complete retinal detachment, advanced siderosis, etc.
2. Electro-oculogram (EOG)
The changes in the resting current when the eyes are moved laterally are picked up by the electrodes placed at the inner and outer canthi. It is absent in retinal dystrophies and degenerations.
Observer Method—It is done in a dark room with a convex condensing lens (+ 30 D, + 20 D, +14 D) and a concave mirror. The lens is held in between the thumb and forefinger of the left hand. The curved surface of the lens is towards the examiner. The periphery of the retina can be seen by scleral depression with the patient in lying down position.
i. The convergent beam is cast by a perforated concave mirror.
ii. The patient’s eye is made myopic by placing a +13D, +20D or +30D convex lens between the
observer and the patient.
iii. A real, inverted enlarged (5 times with +13D and 3 times with + 20D lens) image of the fundus is formed.
Helmholtz invented the direct ophthalmoscope.
Method—The surgeon looks through a self-luminous ophthalmoscope and directs the light upon the pupil. A uniform red reflex or glow is seen. Examination of the fundus is done best at a close distance with accommodation relaxed.
i. The convergent light beam is reflected from the ophthalmoscopic mirror
ii. The incident rays reach the retina causing it to be illuminated.
iii. The emergent rays from the fundus then reach the observers retina through the hole in the mirror. The image is virtual, erect and magnified (15 times in emmetrope eye).
Cotton-wool spots are caused by ischemic damage to nerve fibers
Compensatory proliferation of vessels
Diabetes and hypertension are the main causes
(cellular debris) build-up