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Monthly Archives: September 2013

Oculomotor Nerve Nuclei ,Origin,Course,Branches,Testing and palsy

Oculomotor Nerve

Oculomotor Nerve Definition: is the 3rd of 12 paired cranial nerves. It enters the orbit via the superior orbital fissure and controls most of the eye’s movements, including constriction of the pupil and maintaining an open eyelid by innervating the levator palpebrae superioris muscle. The oculomotor nerve is derived from the basal plate of the embryonic midbrain. Cranial nerves IV and VI also participate in control of eye movement. It is somatovisceral nerve. ... Read More »

Entoptic Phenomenon Notes

The blue field entoptic phenomenon or Scheerer's phenomenon

Entoptic Phenomenon Definition: are visual effects whose source is within the eye itself. (Occasionally, these are called entopic phenomena, which is probably a typographical mistake.) ENTO=WITH IN , OPTIC= EYE, ENTOPTIC=WITH IN THE EYE In Helmholtz’s words; “Under suitable conditions light falling on the eye may render visible certain objects within the eye itself. These perceptions are called entoptical.” Entoptic images have a physical basis ... Read More »

Retinoscope and Retinoscopy Notes

Retinoscope

Retinoscope  Definition: A retinoscope is an instrument used to objectively determine the refractive power of the eye. It works by allowing the examiner to project a beam of light into the eye and then observe the light as it is reflected back out of the eye.  The emerging light will change as it passes through the optical components of th eye, ... Read More »

Focimeter (Lensmeter) Notes

Focimeter

Focimeter Definition: An ophthalmic instrument. It is mainly used by optometrists and opticiansto verify the correct prescription in a pair of eyeglasses, to properly orient and mark uncut lenses, and to confirm the correct mounting of lenses in spectacle frames. Lensmeters can also verify the power of contact lenses, if a special lens support is used. Focimeter Components: A simple lensmeter cross sectional view. 1 – Adjustable eyepiece 2 – ... Read More »

Synoptophore Notes

Synoptophore

Synoptophore Definition: This is an Ophthalmic Instrument, used for diagnosing imbalance of eye muscles and treating them by orthoptic methods. Synoptophore Uses: All the standard measurements and treatments are possible on this instrument including assessment of the angle alpha, the objective angle, abnormal retina correspondence, cyclophoria, hyperphoria and horizontal vertical vergences. Synoptophore Components: An automatic flashing unit allows each eye ... Read More »

Haidinger’s brush Notes

Haidinger's brush

Haidinger’s brush appears on computer screens and blank areas of sky, and it’s caused by the way our eyes respond to polarized light. The apparition looks like two fuzzy bowties, a blue one and a yellow one, overlapping each other at 90 degrees. The rendering above simulates the effect, but it actually appears smaller, about the size of your thumb extended ... Read More »

Ptosis Causes,Diagnosis and Treatment Notes

ptosis eye

Ptosis Definition: Ptosis is Drooping or falling of the upper or lower eyelid. The drooping may be worse after being awake longer, when the individual’s muscles are tired. This condition is sometimes called “lazy eye”, but that term normally refers to amblyopia. If severe enough and left untreated, the drooping eyelid can cause other conditions, such as amblyopia or astigmatism. This is why it is ... Read More »

Ectropion Causes, Diagnosis and Treatment Notes

Ectropion

Ectopion Definition: Ectropion is the turning out of the eyelid (usually the lower eyelid) so that the inner surface is exposed. Ectropion Causes: Congenital Aging Scarring Mechanical Allergic Facial nerve palsy Anti-cancer treatments such as erlotinib, cetuximab, and panitumumab, which block the function of EGFR (the epidermal growth factor receptor). Ectropion Symptoms: Dry, painful eyes Excess tearing of the eye (epiphora) Eyelid turns outward ... Read More »

Entropion Causes, Diagnosis and Treatment Notes

entropion

Entopion Definition: Entropion is the turning in of an edge of an eyelid, causing the lashes to rub against the eye. It usually is seen on the lower eyelid. Entropion Causes: Congenital Aging creating loose skin and stretched and loose ligaments and muscles. Scarring Spasm An eye infection called trachoma is still common in North Africa and South Asia and this can cause scarring of ... Read More »

Chalazion Causes, Diagnosis and Treatment Notes

Chalazion Excised

Chalazion Diagnosis and Treatment Notes Chalazion Definition : is a cyst in the eyelid that is caused by inflammation of a blocked meibomian gland, usually on the upper eyelid. Chalazia differ from styes (hordeola) in that they are subacute and usually painless nodules. They may become acutely inflamed but, unlike a stye, chalazia usually point inside the lid rather than on the lid margin Chalazion Diagnosis: Single, nontender, firm nodule ... Read More »

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