How are PCO cataracts removed?
PCO after cataracts are common and treated using a YAG laser to pop a hole through the capsule, thus clearing the visual axis.
OphthoBook-Questions
What is more visually significant, an anterior or posterior located cataract?
Cataracts that are posterior are more visually significant. Seemingly small PSC cataracts can severely affect the vision.
What is PHACO?
This is phacoemulsification, the method the lens nucleus is removed with ultrasonic energy.
What layer of the lens is left behind with cataract surgery?
The outer capsule is left behind with cataract surgery. This creates a pocket in which to place the new implanted lens.
What holds the lens in place?
The lens is held in place by zonules, like springs on a trampoline.
What eyedrop medication is associated with cataract formation?
Long-term use of steroids is associated with premature cataract formation, usually a PSC at the back of the lens.
What is a NSC and who gets them?
A NSC is a nuclear sclerotic cataract. These cataracts are common and occur gradually with aging.
What is a PCO and who gets them?
A PCO is a posterior capsule opacification, an “after cataract” that can form months to years after successful cataract surgery.
What is a PSC and who gets them?
PSC stands for Posterior Subcapsular Cataract, an opacity that forms at the back of the lens. Common in diabetics and oral steroid users.
Will a child with cataract implants need glasses?
Yes. Even if the implant prescription is perfect for distance vision, the child will need bifocals for reading close up.
What is “with the rule” astigmatism?
This is when the axis of the positive cylinder in a pair of glasses is oriented at 90 degrees.
Are babies usually born myopic or hyperopic?
Babies have small eyes and are usually born hyperopic (far-sighted). Fortunately, they can accommodate their lens and still see near objects.
How might hyperglycemia affect a patient’s prescription?
High sugar leads to accumulation of sorbitol in the lens, swelling the lens and creating more myopia (nearsightedness).
What is presbyopia?
This is stiffness to the lens that occurs with age that makes it hard to read without glasses.
What is accommodation?
Accommodation is when the lens becomes “rounder” in order to focus nearby objects onto the retina.
What’s the difference between the axis and power of a cylinder?
A cylinder power (the refracting power of a lens) is 90 degrees from the axis of the cylinder.
What’s the difference between plus and minus cylinder?
These are ways to describe astigmatism in glasses. Ophthalmologists work in “plus” cylinder while optometrists like “minus” cylinder.
What is hyperopia?
A hyperopic (farsighted) eye is a small eye, such that images focus behind the eye. It is treated with plus power lenses.
What is myopia?
This is nearsightedness (also called short-sighted in other countries) which means that you can see near, but have problems with distant objects.
What kind of orbital wall fracture needs to be repaired?
Orbital fractures are repaired if there is muscle trap, enophthalmos, or displacement of the globe.
How do you evaluate a patient with suspected open-globe?
Attempt to get vision, but don’t press on the eye. CT scan. The eye is usually explored and repaired under anesthesia.
Which type of sickle cell patient has more eye problems: type SC or SS?
Type SC seems to have more eye problems (ischemia and bleeding in the retina) than SS (which has more systemic painful crises).
What medication should you avoid in a sickle-cell patient with a hyphema?
Avoid carbonic anhydrase inhibitors, both topical drops and diamox, as this medication acidifies the aqueous fluid and promotes sickling in the AC.
Why do we dilate eyes with internal inflammation?
Dilation paralyzes the iris and this helps with pain control. Dilation also helps break synechia (adhesions) of the iris.
What is traumatic iritis, and how do you treat it?
Traumatic iritis is internal ocular inflammation after blunt injury. It causes pain, photophobia, and redness. Treatment is usually dilation and steroids.
How might an inflammed conjunctiva be a good prognostic sign in cases of chemical eye injury?
An inflamed, red conjunctiva is good as this means that the chemical didn’t “burn away” the conjunctival and episcleral vessels.
What chemical is worse to get in the eye, an acid or base?
Base chemicals (high pH) are worse for the eye. Acids tend to coagulate tissue and limit spread.. Bases tend to denature proteins and penetrate deeper and deeper.
How are chemical injuries to the eye treated?
Irrigation, irrigation, irrigation. The quicker you can irrigate the offending agent, the better the visual prognosis.
How are metal foreign bodies removed from the cornea?
Usually start with a q-tip. Then most people progress to blunt needle or forceps. Residual rust rings are polished off with a spinning Alger brush.
What might make you suspicious for a foreign body inside the eye?
History of high-speed metal (grinding, hammering), decreased pressure, flat anterior chamber. If in doubt get a CT scan.
What is the surgical approach when sewing up lid-margin lacerations?
You need to line up the lid margin first with a big stitch. Then approximate the posterior and anterior layers of the lid with sutures.
What’s the most problematic location for a lid laceration?
Lid lacerations that occur medially (near the nose) are problematic as it may cut through the canaliculus.
What exam findings should you document with an orbital wall fracture?
Orbital rim fractures, enophthalmos, diplopia, and sensation along the V2 distribution.
Which orbital bone is most likely to fracture with blunt orbital trauma?
The orbital floor, the maxillary bone, is the most common orbital fracture.
How do you diagnose a corneal perforation?
A perforation can be diagnosed by using the Seidel test to see if any aqueous fluid is leaking out.
How do you diagnose a corneal abrasion?
Abrasions are easiest seen by bathing the eye with yellow fluorescein dye, and viewing the cornea using a blue light.
What is anisometropia?
When the prescription between the eyes is very different. This makes glasses hard to fit and can cause amblyopia in kids.
What is ROP?
Retinopathy of prematurity occurs in premature newborns. Ischemic retina promotes neovascularization that leads to scars & retinal detachments.
Retinoblastoma is a tumor of what cell in the eye?
This is a tumor that occurs in the photoreceptors.
Name three potential causes of a white pupil in baby?
Congenital cataract, retinoblastoma (rare but dangerous), retinal detachment, ROP. Plus some others …
What eye findings are suspicious for shaken-baby syndrome?
Retinal bleeding in all four quadrants of the retina, and at all levels of retinal depth. Schisis cavities, bone fractures, and others …
What is pseudostrabismus?
This is the “illusion” that the eyes are out of alignment (but they are actually OK). Common in children with prominent epicanthal folds.
What’s the Hirschberg test?
A test for measuring eye alignment by examining the reflection of light off the cornea.
What’s the difference between a tropia and a phoria?
A tropia is an constant alignment problem between the eyes. A phoria is only present when tired or when fusion is broken.
What are potential causes of amblyopia?
Strabismus (eyes out of alignment), anisometropia (eye prescriptions different) and visual obstruction (cataract or droopy lid).
What is amblyopia?
Vision loss from poor nervous system wiring in childhood. It occurs from poor vision in one eye at a young age that isn’t corrected.
How do you diagnose and treat giant cell arteritis?
Diagnoses is by symptoms (temple pain, jaw claudication, polymyalgias, malaise), labs (ESR, CRP, PLT) and temporal artery biopsy. Treatment is steroids.
What’s a Marcus-Gunn pupil?
This is simply a relative afferent pupillary defect (RAPD).
What is a Horner’s pupil?
This is loss of sympathetic tone to the eye that makes the pupil small. It can be caused by tumors or lesions along the sympathetic chain.
What is an Adie’s pupil?
An Adie’s pupil is a dilated pupil caused by paralysis of the parasympathetics that normally constrict the pupil.
What imaging study is best for orbit, apex, and brain?
CT is best for orbit and bone injuries. MRI is best for looking at the brain.
Where do the cranial nerve nuclei sit in the brain?
The 4-4 rule can be used to figure out the location of the nuclei. You’ll need to click the more button to figure this one out.
What kind of workup would you perform for optic neuritis?
You need to consider multiple sclerosis and order an MRI to look for demyelinating lesions.
How does optic neuritis present?
Loss of vision, decreased color vision and contrast sensitivity. Central vision loss is common and some pt’s have pain with eye movement.
What’s the significance of pupil involvement with oculomotor nerve paralysis?
A 3rd nerve palsy with pupil involvement implies a compressive lesion (such as an an aneurysm or tumor) pushing on the nerve.
What does a sixth nerve palsy look like, and what causes it?
6th nerve palsies make the eye turn inward and can occur from HTN, DM, tumor, and high intracranial pressure.
What does a fourth nerve palsy look like and what causes it?
4th nerve palsies are hard to detect. They cause a mild vertical diplopia and can occur from DM, HTN, tumor, congenital damage, and mild head trauma.
What does a third-nerve palsy look like and what causes it?
3rd nerve palsies make the eye turn down and out. Causes include DM and HTN. A blown pupil implies tumor or aneurysm.
What should you first check with a patient complaining of diplopia?
Whether the diplopia is monocular (astigmatism or cataract) or binocular (nerve palsies, etc.)
What antibiotic do we use to cover most corneal abrasions?
A gentle antibiotic like erythromycin ointment can help lubricate the surface. Contact lens wearers need something stronger like cipro.
What is endophthalmitis and how do you get it?
Endophthalmitis is when an infection forms INSIDE the eye. They are always terrible and most occur from recent surgery or prior glaucoma procedures.
What CD4 count do patients with CMV retinitis typically have?
CMV retinitis typically presents when CD4 counts are below 50, though it rarely can present with counts under 200.
What organism do we worry about with contact lens patients?
These patients have higher incidence of pseudomonas. This bacteria tends to be aggresive and requires more rigorous antibiotic coverage.
What is a layer of blood inside the anterior chamber called?
Blood in the anterior chamber is called a hyphema.
What do you call a layer of white pus in the anterior chamber?
This is a hypopyon, a collection of pus in the anterior chamber. It can be from infection (endophthalmitis) or from bad internal inflammation (uveitis).
What findings on exam are consistant with orbital cellulitis?
An infection tracking behind the eye causes obvious symptoms: proptosis, chemosis, double vision, and decreased acuity.
What is the most common type of conjunctivitis in adults and children?
In adults, viral conjunctivitis is most common. In children, bacterial conjunctivitis is more common.
What’s the difference between a corneal abrasion and an ulcer?
An abrasion is non-infected scratch on the corneal surface. An ulcer implies a localized infection in the cornea.
What are the three types of conjunctivitis and how do they present?
Viral conjunctivitis causes redness and watering. Bacterial infection creates mucous and allergic conjunctivitis causes itching/swelling.
Name some oral medications that we check in ophthalmology?
We typically ask about beta-blockers (breathing problems), Plaquenil (retina toxicity) and Flomax.
Describe two methods to check eye pressure?
You can check pressure with Goldmann applanation at the slit-lamp or a hand-held device like the Tono-Pen.
What is presbyopia?
Presbyopia is when the lens hardens as we age. A stiff lens can’t change shape and most people lose the ability to focus at near.
What are the “three vital signs” of ophthalmology?
The three “vital signs” are vision, pupil, and eye pressure. These measurements must be checked prior to dilating the eyes.
What is “pinholing” a patient?
Using a pinhole, you can often improve a patient’s vision when reading the eye chart. Big improvements usually mean they need updated glasses.
What symptoms might a patient with temporal arteritis complain of?
Headaches, scalp tenderness, malaise, weight loss, night sweats, fevers, jaw claudication and muscle aches.
What are the symptoms of dry eye?
Red, watery eyes. Burning and a feeling of the eyes feeling “tired.” Many patients complain of blur with prolonged reading or TV.
What is the swinging light test?
This test is used to check for relative afferent pupillary defect (RAPD). If one pupil dilates as you swing your light back and forth, that eye may have an APD.
What do OU, OS, and OD stand for?
OD is right eye. OS means left eye. OU means both eyes. Dumb, I know … that’s Latin for you!
What is applanation and how do we do it?
Applanation is a method for checking eye pressure by pushing on the eye. The Goldmann applanation tonometer is built into the slitlamp and is the gold standard for checking eye pressure.
Which method of retinal examination gives the most magnified view?
Technically, the “direct ophthalmoscope” gives the most magnified view. Eye doctors, however, prefer small hand-held lenses (the 90-diopter) at the slitlamp.
What is cell and flare?
“Cell” are individual cells floating in the anterior chamber. “Flare” is protein floating in the anterior chamber from inflamed blood vessels.
What are the 8 structures you describe on slit-lamp exam?
EXT (external exam) LL (lids & lacrimation) CS (conjunctiva & sclera) K (cornea) AC (anterior chamber) I (iris) L (lens) V (vitreous)
What are the symptoms of retinal detachment?
Flashing lights and floaters are the primary symptoms. Patients may also describe decreased vision and a “curtain” or “veil” over their vision.
Why are sulfa allergies important to ask about?
Some of the glaucoma drops we use are sulfa-based. Older antibiotics are also sulfa-based, but aren’t used often these days.
How long is the eyeball?
About 24 millimeters. Eyes that are myopic tend to be longer, while hyperopes have shorter eyes.
Where does the nasolacrimal duct drain?
It drains tears into the nose, underneath the inferior turbinate.
What and where is the trochlea?
The trochlea is a fibrous pulley at the superior medial wall of the eye socket (kind of near the bridge of the nose).
Where to do the extraocular muscles originate?
The extraocular muscles mostly originate at the annulus of Zinn, at the back of the eye socket.
How many chambers are there in the eye?
There are actually 3 chambers in the eye – anterior chamber, posterior chamber, and vitreous chamber.
Which muscles open and close the eyelid?
The orbicularis muscle closes the eye. The levator palpebrae opens the eye.
Describe the tear pathway from start to finish.
Tears go from lacrimal & accessory glands, over eye, through punctum, cannaliculi, lacrimal sac, nasolacrimal duct, then nose.
What bones form the orbital walls?
These bones are: 1-Maxillary 2-Frontal 3-Zygomatic 4-Ethmoidal 5-Lacrimal 6-Sphenoid 7-Palatine
What are the layers of the lens and which are removed in cataract surgery?
The lens has three layers. The outer capsule, middle cortex, and the central nucleus.
Why is the cornea clear and the sclera not?
The cornea has well-organized layers of collagen and is relatively dry. When the cornea gets too wet, it gets cloudy and turns white.
Name the layers of the cornea and their function.
The cornea has five layers: epithelium, Bowman’s layer, stroma, Descemet’s membrane, endothelium
Put these layers in order from “inside” to “out”: photoreceptors, ganglion nerves, sclera, and choroid.
Starting from “inside” the eye and moving our way outwards: 1-Ganglion Nerves 2-Photoreceptors 3-Choroid 4-Sclera
What is the ciliary body and what two functions does it serve?
The ciliary body is a band of muscle right behind the iris. It controls the lens shape and produces aqueous humor.
What is the uvea?
The uvea is comprised of three structures: the iris, ciliary body, and the choroid.
Why can’t we look at the trabecular meshwork directly?
Because of total internal reflection. Light from the trabecular meshwork reflects back into the eye at the tear-film-air interface. You need a gonio lens.
You have a patient with a corneal thickness of 600 microns, and measured pressure of 15. What is the actual pressure?
Normal corneal thickness is about 540 microns, thus this patient has thick corneas. Real pressure is probably close to 13.
What is pseudoexfoliation syndrome?
PXF is a common condition where flaky material forms on the surface of the lens. It can cause glaucoma and lens dislocations during surgery.
What is pigment dispersion glaucoma?
PDS is a type of glaucoma that occurs from pigment rubbing off the back of the iris. The pigment can clog the trabecular meshwork.
How does neovascular glaucoma occur?
This occurs from neovascular blood vessels forming on the iris and growing up into the trabecular meshwork … blocking outflow of aqueous.
What is the “ISNT rule” in glaucoma?
The ISNT rule describes the thickness of the neuro-retinal rim in healthy eyes: the optic nerve is thickest Inferiorly and thinnest Temporally.
What are some risk factors for angle-closure glaucoma?
Farsightedness, family history of glaucoma attack, medications that dilate pupil, medications that dilate the pupil, prior attack in other eye.
What are some risk factors for open-angle glaucoma?
High eye pressure, optic nerve cupping, race, family history, and thin corneas.
How does applanation work?
Applanation works by measuring the amount of pressure it takes to flatten a defined area of cornea. Like kicking a car tire to estimate pressure.
What’s normal corneal thickness and why do we check it?
Normal corneal thickness is about 540 microns. Corneal thickness is needed to evaluate glaucoma risk and to calibrate pressure readings.
What’s a normal eye pressure?
Normal eye pressure is usually considered 10 to 21 mmHg.
What’s the difference between open and closed-angle glaucoma?
Chronic (open-angle) glaucoma is common and occurs from chronically high pressure. Acute (angle-closure) glaucoma is rare and a major emergency.
Describe the aqueous pathway from start to finish.
Aqueous is produced by the ciliary body. It fills the posterior chamber, through the pupil into the anterior chamber. Aqueous drains out the “TM” into the canal of Schlemm.
What is glaucoma?
Glaucoma is gradual death of the optic nerve, often associated with high intraocular pressure.
What is a PVD?
This is a posterior vitreous detachment that occurs when the vitreous jelly contracts inside the eye. The leading cause of floaters.
What are drusen?
Drusen are yellow lipid deposits that form in Bruch’s membrane in the retina. They are often a finding/precursor to macular degeneration.
What is macular degeneration and what causes it?
Macular degeneration is premature aging of the central retina. It causes decreased central vision and is a common cause of vision loss.
What are hard exudates?
Hard exudates are yellow spots seen in the retina. They are lipid deposits left behind after swelling (such as from diabetic retinopathy).
By what mechanisms can patients with diabetic retinopathy lose vision?
Macular edema, premature cataracts, vitreous hemorrhage, and tractional retinal detachment.
How do we treat proliferative diabetic retinopathy?
Neovascularization is typically treated with PRP laser. Occasionally, anti-VEGF medications are injected to decrease retinal swelling.
What level of the retina do dot-blot hemorrhages occur compared to flame-hemorrhages?
Dot-blot hemorrhages are deeper and more common with diabetes, Flame hemorrhages occur in superficial layers and often seen with HTN.
Why is the macula susceptible to ischemia with retinal detachments?
The macula derives its nutrition from the choroid underneath. When detached, the rods and cones die from lack of blood supply.
How do we classify diabetic retinopathy?
We use two categories: NPDR (non-proliferative diabetic retinopathy) and the more advanced PDR (proliferative diabetic retinopathy).
What four structures do we check on retinal exam?
With documenting retinal findings, the four main structures checked are: Macula, Vessels, Periphery, and Disk (optic nerve).