This sections is the largest and most difficult section. I put this chapter
first because it is good to get the largest section out of the way, but in
reality the material in this chapter calls in material from chapters that come
after it. You may have to jump around the a book a little to get the most out of
There are a lot of surgeries that patients have to have in ophthalmology. When
patients have questions you are expected help answer their questions. The COA
exam reflects this. It will expect you to know the differences among the many
Oculoplastics have to do with the look of the eye. If a patient has ptosis,
droopy eyelids, the surgeon will prepare a surgery to raise the eye lids.
These surgeons will also preform enucleations and eviscerations.
Enucleation is the removal of the entire eyeball leaving only the muscles and
orbit intact. Evisceration is the removal of the entire contents of the eye
leaving the sclera.
Enucleation nukes the entire eye. Evisceration leaves a visible sclera.
Keratoplasty is when a dying part of the cornea is replaced with donated
corneal tissue. This is also known as corneal grafting or a corneal transplant.
Pterygium surgery is the removal of tissue, which grows over the cornea.
Refractive surgeries – Review my post on Assisting in Surgical
Procedures under the section
refractive surgery . Be able to describe LASIK, LASEK, PRK, PTK, and RK.
Physicians can correct strabismus “crossed-eyes”. They do this by
either strengthening a muscle by doing a resection or by weakening a muscle
which is a recession. Resections are performed by shortening the tendon. A
recession is performed by attaching the muscle further back on the eye.
Cataract surgery is very common in ophthalmology. The COA exam will expect you
to know a lot about cataract surgery.
Symptoms Glare – Patients will often
say that they see glare from oncoming traffic while driving at night. Or see
glare in a room with low lights. Halos – Halos are rings of light around a
source of light. This is another common complaint. Patients will state that they
see halos around headlights. Special tests related to cataract surgery are:
Corneal Topography – This makes a typographical map of the cornea which
gives the provider information about the shape and curvature of the cornea.
Surgeons use this while planning for cataract surgery. Read more about corneal
PAM (Potential Acuity
Meter) estimates the vision a patient may have after cataract surgery. The PAM
is a device which attaches to a slit lamp. When the patient looks into the PAM a
visual acuity chart is seen. The visual acuity chart lights up helping the
patient see it through media opacities.
BAT (Brightness Acuity Test) gives
the most accurate idea of a patient’s visual disability. If a patient has
a dense cataract it they will read worse when testing visual acuity with the
BAT. Many insurances require that a patient have a visual acuity of 20⁄40 or
20⁄50 before they will cover the cataract surgery. The BAT helps achieve this
goal. I patient with a dense cataract may have a visual acuity of 20⁄25, but
with the BAT see 20⁄60.
Glaucoma is death of the optic nerve. High eye pressure is associated with
glaucoma. A decrease in aqueous outflow causes eye pressure to increase. Aqueous
is produced by the ciliary body, flows through the pupil, over the iris, and out
through the trabecular meshwork.
Open Angle Glaucoma– Open angle
glaucoma is the most common form of glaucoma. It occurs when the trabecular
meshwork is not functioning properly. It is like have a clogged drain. The
aqueous can’t filter out effectively so more pressure builds up. Treatment for
Open Angle Glaucoma- The physician will first start with drops to lower eye
pressure. He will then move to a trabeculectomy. A trabeculectomy provides
an alternate route for fluid to travel. A laser is used to poke a hole in the
limbus. The aqueous then flows underneath the conjunctiva. This area is a
bleb. Remember Pressure = Force/Area. This surgery increases area which
Closed Angle Glaucoma – There is an angle that
is made between the cornea and the iris. When this angle shrinks fluid can’t
drain out of the trabecular meshwork. Treatment for Closed Angle Glaucoma- The
most common treatment for acute angle closure glaucoma is an Iridotomy. An
iridotomy is hole that is cut in the iris with a laser. This increases the
buildup of pressure that increases behind the iris.
Vitrectomy – A vitrectomy is the removal of vitreous from the eye. If a
patient has had a vitreous hemorrhage the surgeon may consider performing a
vitrectomy. The physician may also decide to do a vitrectomy if he wants to do
retinal surgery. When a vitrectomy is performed oil or a gas bubble is placed
inside the eye to help hold its shape.
Photocoagulation is the using a laser to coagulate bleeds to stop bleeding.
Patients with advanced diabetic retinopathy may need photocoagulation.
Anti-VEGF injections – VEGF(Vascular Endothelial Growth Factor) causes new
blood vessels to grow. It most cases this is a good thing, but when this occurs
in the retina it can cause vision problems. Patients that are experiencing
advanced neovascularization (new blood vessel growth) may receive anti-VEGF
treatments which stop neovascularization.
Systemic & Ocular Diseases
Diabetes – High blood sugar causes problems in both the lens and the
retina. Glucose is deposited in the lens. The high concentration of glucose in
the lens causes a large osmolarity gradient between the concentration of glucose
in the aqueous humor outside of the lens and the concentration of the glucose in
the lens. To compensate for this high osmolarity gradient water moves from the
aqueous to the lens which causes the lens to swell. The swollen lens causes
blurry vision. In the retina two types of diabetic retinopathy (retinal death)
NPDR (Non Proliferative Diabetic Retinopathy) – Proliferation refers
to the growth of new blood vessels. With NPDR a physician will see dots.
These dots are small aneurysm of retinal blood vessels.
PDR (Proliferative Diabetic Retinopathy)
Hypertension – Hypertension causes ischemia(blood clots) both systematically and in the retina. When an examiner sees “cotton wool spots” he is referring to areas of ischemia on the retina.
Safety glasses can be prescribed for people who weld, are at risk for chemical
contact with the eye, monocular patients, and for safety in street wear. Safety
lenses are lenses which are shatter resistant.
For this section I would recommend looking at
pharmacology. Instruct patients
to instill topical eye drops by pulling down the lower lid and looking up.
Applying pressure to the lacrimal ducts will decrease the amount of solution
absorbed by the body. Instruct patients to instill ointment by looking up,
pulling down the lower lid, and instilling the ointment in the lower lid.
I lumped these sections together because all of this information is covered
in Assisting in Surgical
Procedures This post breaks
down both major and minor procedures.
Pressure patches are used to help the eye heal. The difference between a
pressure patch and an eye shield is that a pressure patch keeps the eye from
moving. To apply a pressure patch the technician places a patch to the eye and
tapes the patch from forehead to cheek. If the patient can move their eye after
the patch has been applied then it must be redone until the patient can no
longer open his eye. An eye shield is used to protect the eye. Eye shield
are given to patients who have had surgeries. This keeps the eye protected from
When guiding a low vision patient to the exam room offer your arm. Have the
patient hold near your elbow as you guide them to the room. If the provider is
running behind inform the patients.
Emergencies – Must be seen within minutes
Retinal artery occlusions
Penetrating eye injuries
Sudden Vision loss
Urgent – Must be seen within the same day
Narrow angle closure glaucoma
Semi-urgent – Should be seen within days
Previously undiagnosed glaucoma
Gradual blurry vision
Needs new glasses
NOTE: The above list of triage cases relied heavily on The Ophthalmic Assistant 8th edition.