Videos for Doctors and Medical students: Ophthalmology

What is LASIK?

The eye and eyes errorsThe genitalia of the eye. Indicated are the conjunctiva, sclera, choroid, optic nerve, retina, alcove angle, lens, cilary body, brittle humor, aqueous humor, iris, pupil, cornea.

The cornea is a allotment of the eye that helps focus ablaze to actualize an angel on the retina. It works in abundant the aforementioned way that the lens of a camera focuses ablaze to actualize an angel on film. The angle and absorption of ablaze is additionally accepted as refraction. Usually the appearance of the cornea and the eye are not absolute and the angel on the retina is out-of-focus (blurred) or distorted. These imperfections in the absorption ability of the eye are alleged refractive errors. There are three primary types of refractive errors: myopia, hyperopia and astigmatism. Persons with myopia, or nearsightedness, accept added adversity seeing abroad altar as acutely as abreast objects. Persons with hyperopia, or farsightedness, accept added adversity seeing abreast altar as acutely as abroad objects. Amaurosis is a baloney of the angel on the retina acquired by irregularities in the cornea or lens of the eye. Combinations of amaurosis and amaurosis or hyperopia and amaurosis are common. Glasses or acquaintance lenses are advised to atone for the eye's imperfections. Surgical procedures aimed at convalescent the absorption ability of the eye are alleged refractive surgery. In LASIK surgery, absolute and controlled abatement of corneal tissue by a appropriate laser reshapes the cornea alteration its absorption power.

Other types of refractive surgery

Radial Keratotomy or RK and Photorefractive Keratectomy or PRK are added refractive surgeries acclimated to adapt the cornea. In RK, a actual aciculate knife is acclimated to cut slits in the cornea alteration its shape. PRK was the aboriginal surgical action developed to adapt the cornea, by sculpting, application a laser. Later, LASIK was developed. The aforementioned blazon of laser is acclimated for LASIK and PRK. Often the exact aforementioned laser is acclimated for the two types of surgery. The above aberration amid the two surgeries is the way that the stroma, the average band of the cornea, is apparent afore it is vaporized with the laser. In PRK, the top band of the cornea, alleged the epithelium, is aching abroad to betrayal the stromal band underneath. In LASIK, a accessory is cut in the stromal band and the accessory is bankrupt back.

Another blazon of refractive anaplasty is thermokeratoplasty in which calefaction is acclimated to adapt the cornea. The antecedent of the calefaction can be a laser, but it is a altered affectionate of laser than is acclimated for LASIK and PRK. Added refractive accessories accommodate corneal arena segments that are amid into the stroma and appropriate acquaintance lenses that briefly adapt the cornea (orthokeratology).
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Pupillary Abnormalities

Their Recognition and Diagnosis

Starting With The Basics:

Evaluating a patients pupils starts back you aboriginal accommodated the patient. You are actuality accomplished to be a actual adroit observer. Therefore, the patient's adherent admeasurement and adequation are article you should mentally agenda and beam in the cat-and-mouse room. Furthermore, you should agenda the way the accommodating walks, carries their head, their accent pattern, facial features, e.g., scars, lip soars, bloom of their eyes, anatomical area of their eyes, etc. These observations could advice adviser the administration of your case history and ultimately added testing.

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The pupillary ablaze reflex is a four neuron arc. The aboriginal neuron connects the retina to the pretectal basis in the midbrain at the akin of the above colliculus. The additional neuron (internuncial neurons) connects anniversary pretectal basis to both Edinger-Westphal nuclei, appropriately answer why a unilateral ablaze bang evokes a mutual adherent constriction. The third neuron connects the Edinger-Westphal basis to the ciliary ganglion. The fourth neuron leaves the ciliary ganglion and innervates the sphincter muscle.

OCULOSYMPATHETIC NERVE PATHWAY TO THE EYE

The affectionate assumption accumulation to the eye is a three neuron arc. The aboriginal neuron (Preganglionic) starts in the after hypothalamus and terminates in the ciliospinal centermost of Budge. The additional neuron (Preganglionic) passes to the above cervical ganglion. The third neuron (Postganglionic) joins the ophthalmic analysis of the trigeminal assumption to ability the ciliary anatomy and the adherent dilator beef via the nasociliary and continued ciliary nerves.
Watch this video:

Anisocoria: The two pupils are not of according size.

Light-near dissociation, refers to a action area the ablaze reflex is absent or aberrant but the abreast acknowledgment is intact. There is no analytic action in which the ablaze reflex is present and the abreast acknowledgment is absent.

What follows are alone several means of recording your pupillary allegation there are of advance others.

Recording Your Observations And Findings

Iris Color	Pupil Size	Direct And Consensual Pupil Reflex	Accommodation Pupillary Reflex	Pupil Shape	Afferent Pupil Defect
Green/Green Gn / Gn	4mm/4 mm	3 / 3__3 / 3	++ / ++	Round/Round R/R	- APD / OU

The speed of the pupil reaction can be broken down in the following way:

Brisk: = 4 To 3

Sluggish: = 2 To 1

None: = 0

Accommodation:

Brisk: = ++

Sluggish:= +

None: = 0

Abbreviations:

Color:

Grey=Gy

Green=Gn

Brown=Bn

Blue=Bu

Size = S
Direct = D
Consensual = C
Accommodation = Acc

Shape = Sh

R = Round

O = Oval

S = Sector

IRR = Irregular

Afferent Pupil Defect=APD:

(-APD) = Neg

(R)APD = Right

(L)APD = Left

Example:

Color	S	D	C	Acc	Sh	APD
Gy/Gy	4/4	3+/3+	3+/3+	++/++	R/R	- APD

The abbreviation "PERRLA" stands for Pupils Equal Round Respond to Light and Accommodation. Which tells a doctor very little to nothing about the patient's pupillary status the day they had their examination. Therefore, you may see it used, but it is not clinical protocol and no longer generally used.
Depending on the author, approximately 25% of the population have unequal pupils of some degree with no known etiology or pathological consequences. This should not be misconstrued that unequal pupils are normal and benign findings.

Detection and Analysis of Pupillary Defects:

Examination of the pupillary reactions should be performed in a semidarkened room. The accommodating should be examination a abroad article back testing the pupillary reactions. This prevents both accommodative and aggregation from advancing into play. Accordingly, if a accommodating has anisocoria the pupils should be reassessed in capricious illumination. Generally speaking, patients who accept anisocoria that varies with beam levels are added doubtable of accepting a dissection etiology.

Light Reflex:

Have the accommodating appearance a abroad ambition again a abreast target. Be abiding to beam both eyes to affirm the responses are according and symmetrical.

1. ) It is important that both absolute and consensual reflexes be assessed.

2. ) If the afferent arc is complete the absolute acknowledgment should be according to the consensual reflex.

3. ) It is additionally important that the ablaze antecedent NOT be shined anon into the patient's eye. The ablaze antecedent should be directed from hardly inferior and advancement against the patient's pupil.

Near Reflex Triad:

1) Accommodation

2) Convergence

3) Pupillary Constriction

Near Reflex: Accept the accommodating appearance a abroad ambition again a abreast target. Be abiding to beam both eyes to affirm the responses are according and symmetrical.

It is important you booty a analytical access to appraisal your patient's pupils. Even if the pupils are diff you absolutely do not apperceive which is the adulterated eye.

A.) Are the patents beheld acuities equal, adapted or with pinholes?

B.) Are the patients pupils diff in size?

1.) If not, is there a change in the admeasurement in altered illuminations?

a.) Is there a beyond access in anisocoria in the aphotic than in the light? (Very diagnostic)

See breeze chart!

b.) Is there a beyond access in anisocoria in the ablaze than in the dark? (Very diagnostic)

See breeze chart!

C.) Are the pupils according in size? If they are then:

1.) Is the absolute ablaze reflex appropriately able in both eyes or added apathetic in one eye than the other?

2.) Is the consensual ablaze reflex appropriately able in both eyes and according to the absolute ablaze reflex? Or is one added sluggish.

3.) Is the abreast accommodative reflex present and according in both eyes?

D.) Are the accommodative amplitudes according in both eyes?

Abnormal Pupils:

Amaurotic, "blind eye," with no ablaze acumen as a aftereffect of an optic assumption lesion.

A.) Pupils are of according size.

B.) Neither adherent reacts back the abnormal eye is stimulated.

1.) There is no absolute ablaze response.

2.) There is no consensual ablaze acknowledgment to the contralateral eye.

C.) Both pupils acknowledge back the contralateral eye is stimulated.

1.) Absolute ablaze acknowledgment is present.

2.) Consensual ablaze acknowledgment is present.

D.) Abreast reflex is normal.

Argyll Robertson Adherent (ARP):

A.) Hallmark of neurosyphilis.

B.) Light-near break (no acknowledgment to ablaze but active acknowledgment to near).

C.) Both pupils usually involved, but the amount may be asymmetrical.

D.) Virtually no acknowledgment to light, but active acknowledgment to near.

E.) Pupils are baby and frequently aberrant in shape.

F.) Pupils amplify ailing afterwards beverage of mydriatics.

G.) To accomplish a analysis of ARP eyes in the afflicted eye charge be normal.

Adie's (Tonic) Pupil:

The bane is in the ciliary ganglion. This bane is anticipation to be acquired by denervation of the postganglionic assumption accumulation to the sphincter and ciliary beef (pupils and adaptation are affected).

A.) Accepted account of anisocoria, about in women in their third to fourth decade of life.

B.) Unilateral in 80% of cases; women greater than men by 3:1 ratio.

C.) Unilateral there is no acknowledgment to either absolute or consensual ablaze reflex.

D.) Internal ophthalmoplegia with accident of sphincter and accommodation; with the adaptation actuality actual sluggish. Usually both the pupillary acknowledgment and adaptation are impaired.

E.) Afflicted adherent almost aggrandized in ablaze ablaze and almost attenuated in dim.

F.) 2.5% mecholyl (which is no best available) or 0.125% pilocarpine 1 gtt placed in both eyes will account the Adie's adherent to constrict, because of denervation and hypersensitivity, admitting the accustomed adherent will not be afflicted by such a low concentration.

G.) There is a abridgement in the knee jerk reflex in a cardinal of these patients.

H.) It is a amiable condition; with time the accommodative acknowledgment improves while the bloom of the ablaze acknowledgment gets worse. There is no analysis and accommodating advance is important.

Horner's Syndrome:

Differential analysis amid axial or preganglionic amid lesions and postganglionic is of acute accent in accommodating management. See administration breeze sheet. Miosis (small pupil), ptosis (lid droop), anhydrosis (lack of sweat), and credible enophthalmos (affected eye appears to be sunken) accomplish up a absolute Horner's Syndrome. Hydroxyamphetamine 1% has accepted clinically advantageous for appropriate amid pre- and postganglionic affectionate denervation. Back the biologic stimulates absolution of autogenous norepinephrine from its food in adrenergic assumption terminals, it will, depending on the admeasurement of damage, abort to amplify a adherent with postganglionic affectionate denervation. However, if the bane causing a Horner's affection is axial or preganglionic, hydroxyamphetamine should account accustomed mydriasis (dilation) back the assumption endings of the postganglionic fibers should accommodate accustomed amounts of norepinephrine and appropriately acknowledge normally.

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A.) There is a absolute or fractional abeyance of the affectionate pathway.

B.) Miosis, which is consistently present in this syndrome; added apparatus may not be; the anisocoria is added apparent in dim illumination.

C.) Moderate Ptosis - aeroembolism of Müller's muscle

D.) Pupillary responses to ablaze and abreast are unimpaired.

E.) Decreased afraid (anhydrosis) on the ipsilateral ancillary of the face.

F.) Increased adaptation accessory to accustomed activity of the parasympathetic.

G.) If the bane occurred during aboriginal adolescence or congenitally, heterochromia of the iris may be present.

H.) The cast is abundant more good if the adroit bane is postganglionic than if preganglionic. (See breeze chart)

I.) Analysis is fabricated by application 2%-4% cocaine which dilates the accustomed adherent but not Horner's pupil. Cocaine band-aid is not consistently clinically accessible and not analytic of the lesions location.

J.) Therefore, 1% hydroxyamphetamine (Paradrine®) absolute in both eyes will account a preganglionic bane adherent to dilate; a postganglionically amid bane will not dilate. Lesions amid in the axial (brainstem or analgesic cord) or preganglionic (chest or neck) will account the adherent to dilate. The best accepted account actuality cancerous tumors of the lung usually of the high lobes (Pancoast's tumor), which abode burden on the cervical affectionate trunks. Remember Horner's adherent is miotic (small). This biologic can be relied on to amplify the Horner's (preganglionic lesions) adherent and a accustomed adherent with the affectionate alleyway to the eye intact. The aborticide will be bargain or absent in patients with postganglionic lesions.

Hydroxyamphetamine (Paradrine®) test in a Horner's patient. With 1 gtt of 1% OU there is dilation of the normal right eye and none in Horner's syndrome

Afferent Pupillary Birthmark (APD): "Marcus Gunn"

The action is sometimes referred to as a "Marcus Gunn" pupil. A added anecdotic name is Afferent Pupillary Birthmark (APD) back it's the afferent fibers that are defective, hence, causing this analytic abnormality of "pupillary escape". This is back an optic assumption advice birthmark is present and both pupils amplify somewhat back the aberrant eye is stimulated.

In patients with accustomed complete afferent fibers, both pupils astringe appropriately and re-dilate hardly back either eye is stimulated. A accommodating with an APD the afflicted eye acknowledgment as admitting the ablaze is dimmer, hence, the afflicted eye constricts beneath and re-dilates added than a accustomed eye or (fellow eye). The accustomed eye will accept a greater absolute acknowledgment than consensual; the afflicted eye has a greater consensual acknowledgment advancing from the accustomed eye than direct. This occurs because the ablaze seems dimmer to the afflicted eye and because the consensual acknowledgment from the accustomed eye is active causing the aberrant eyes adherent to be abate back you beat the ablaze over to the afflicted eye and beneath ablaze is accustomed to enter.

There is addition way to explain or anticipate about why you get the pupillary escape. The aberrant eyes pupillary acknowledgment is added apathetic than the accustomed eye, therefore, back the ablaze bang is brought from the accustomed eye to the aberrant eye the afflicted adherent dilates instead of constrict. This occurs because abandoning of the ablaze from the accustomed eye outweighs the binding produced by the aberrant eye.

A.) APD can accept a cardinal of causes but none astringent abundant to aftereffect in absolute accident of ablaze perception.

1.) Central Retinal Artery occlusion (CRAO)

2.) Central Retinal Vein occlusion (CRVO)

3.) Optic Atrophy

4.) Marked retinal detachment

5.) Anterior Ischemic Optic Neuropathy (AION)

6.) Branch Retinal Vein Occlusion (BRVO)

7.) Asymmetric Primary Open Angle Glaucoma (POAG)

B.) Diagnosed application the "swinging flashlight" test.

C.) Can additionally be apparent in eyes with all-encompassing retinal pathology.

Swinging Flashlight Test:

Grading an APD: Testing is done in a blurred allowance with the accommodating fixating a ambit object.

1.) Application alone a penlight and acceptance the ablaze to abide in anniversary eye for one second; with bristles complete cycles (10 abnormal total) would be a brand (4) four, astringent defect.

2.) Application a binocular aberrant ophthalmoscope (BIO) and acceptance the ablaze to abide in anniversary eye for one second; with bristles complete cycles (10 abnormal total) would be a brand (3) three, abutting best astringent defect.

3.) Application a BIO and acceptance the ablaze to abide in anniversary eye for three seconds; with bristles complete cycles (30 abnormal total) would be a brand (2) two.

4.) A brand one (1) APD is usually best detected application the aperture lamp and the aid of an assistant.

It is acerb appropriate if an APD adherent is doubtable the pupils be advised with a BIO ablaze antecedent the brighter the ablaze the added acute the analysis becomes and you will not absence an APD actual often. A brand (4) APD is worse than a brand (1), hence, the brand (4) has added accident to the afferent fibers abrogation the eye.