1.5 million surgeries are performed annually in US.
Local or topical anesthesia, sonographic breakdown and aspiration of the lens, placement of an artificial lens
Under an operating microscope, a small incision (3 mm) is made in the eye.
Tiny surgical instruments are used to break apart and remove the cloudy lens from the eye.
The back membrane of the lens (called the posterior capsule) is left in place.
The surgeon creates an opening in the capsule, which is a micro-thin membrane surrounding the cataract. This procedure is called capsulorhexis.
It requires extraordinary precision since the capsule is only about four-thousandths of a millimeter thick! (thinner than a RBC)
Phacoemulsification is the procedure in which ultrasonic vibrations are used to break the cataract into smaller fragments.
These fragments are then aspirated from the eye.
First the denser central nucleus of the cataract is removed.
Then the softer peripheral cortex of the cataract is removed using an irrigation/aspiration handpiece.
The posterior capsule is left intact to help support the intraocular lens (IOL) implant
The intraocular lens is folded and passed through the tiny incision inside the “capsular bag”.
In the following illustration, the lens is being inserted via an “injector”. This instrument keeps the incision small while allowing implantation of a 6 mm lens through a 3 mm (or even smaller) incision
Intra Ocular Lens
Intra Ocular Lens
Age-related macular degeneration
It is a degenerative condition of the macula (the central retina).
It is the most common cause of vision loss in the United States in those 50 or older
Prevalence increases with age
ARMD is caused by hardening of the arteries that nourish the retina.
This deprives the retinal tissue of oxygen and nutrients that it needs to function and thrive.
Diagnosis: presence (early) of drusen and (late) of choroidal neovascularization
Treatment is controversial
Vitamins, antioxidants, zinc
Prophylactic laser therapy
Vision with macular degeneration
Symptoms of Macular degeneration
The classic symptoms are
Decreased central visual acuity,
Metamorphopsia or image distortion,
and a central scotoma
Dry macular degeneration
The dry type is much more common
Typically results in a less severe, more gradual loss of vision.
Characterized by drusen and loss of pigment in the retina.
Drusen are small, yellowish deposits that form within the layers of the retina.
Non-Exudative macular degeneration
The drusen allow an angiogenic stimulant (such as vascular endothelial growth factor) to promote the growth of underlying choroidal blood vessels into the subretinal space and retina.
These tufts of neovascularization are fragile and have a propensity to leak and bleed, eventually forming a fibrovascular scar and resulting in irreversible vision loss
Exudative macular degeneration
Patient with wet macular degeneration develop new blood vessels under the retina.
This causes hemorrhage, swelling, and scar tissue but it can be treated with laser in some cases
Exudative macular degeneration
ARMD with subretinal hemorrhage Choroidal neovascularization and subretinal hemorrhage in a patient with late maculopathy.
Hallmark of diagnosis of choroidal neovascularization has been the fluorescein angiogram .
It pinpoints the location and extent of neovascular membranes and can guide laser photocoagulation.
Unfortunately, only about 13% of angiograms show a treatable localized lesion, or "classic" choroidal neovascularization. The other 87% show diffuse,, hyperfluorescent lesions that are not amenable to laser photocoagulation
Iodocyanine green dye technique
Currently there are no treatments or preventive measures, other than vision aids, for patients with dry macular degeneration.
The only clinically proven treatment for wet macular degeneration is laser photocoagulation
Laser treatment guidelines vary, depending on the proximity of choroidal neovascularization to the fovea.
The common types of lesions are extrafoveal (200 to 2,500 micrometers from the fovea), juxtafoveal (1 to 199 micrometers from the fovea), and subfoveal (directly below the fovea).
Laser photocoagulation is a destructive treatment in which tissue is ablated by heat.
This treatment quandary was investigated by the multicenter group
Their studies indicate that although patients treated with laser showed an immediate decrease in vision,
-20% of treated eyes had severe vision loss after 3 years,
-compared with 37% of untreated eyes.
However, the final visual acuities were very poor for both groups (20/320 for treated and 20/400 for control subjects
It is still experimental.
Photodynamic therapy, uses a photosensitive dye, which, when activated in the retinal vasculature by a light source, produces a thrombus that closes neovascular vessels.
Since the immunologic and coagulating systems naturally break down thrombi, this therapy may be a fast-acting temporizing measure, rather than a long-term treatment
Recommendations for ARMD
Use a halogen light. These have less glare and disperse the light better
Shine the light directly on your reading material. This improves the contrast and makes the print easier to see.
Use a hand-held magnifier.
Try large-print or audio books. Most libraries and bookstores have special sections reserved for these books.
Consult a low vision specialist. -specially trained to help visually impaired patients improve their quality of life.
Among persons who have had type 2 diabetes for at least 10 years:
70% show retinopathy.
nearly 10% show proliferative disease.
Duration of disease and control of blood sugar are the most important variables.
Prevention: Tight glucose control and blood pressure control ( ≤ 130/80)
Treatment: Panretinal laser photocoagulation inhibits growth stimulus for neovascularization.
DIABETIC RETINOPATHY STAGES
DIABETIC RETINOPATHY: NONPROLIFERATIVE STAGE
DIABETIC RETINOPATHY: NONPROLIFERATIVE STAGE Intraretinal edema and exudate in the superior macular region with type 2 diabetes.
DIABETIC RETINOPATHY: PREPROLIFERATIVE STAGE
Venous caliber changes
Intraretinal microvascular abnormalities
DIABETIC RETINOPATHY: PROLIFERATIVE STAGE
Neovascularization of the retina
Neovascularization of the disc
Neovascularization of both
DIABETIC RETINOPATHY: PROLIFERATIVE STAGE Neovascularization of the disc in a patient with proliferative retinopathy.
Affects > 2.25 million Americans aged >40 years
Second most common cause of blindness worldwide. Most common cause of blindness among black Americans
$1 billion for glaucoma-related Medicare and Medicaid payments and disability
Defined as characteristic optic nerve head damage and visual field loss
Progressive optic nerve damage
Progressive optic nerve damage (indicated by the cup to disc ratio) caused by glaucoma.
Notice the pale appearance of the nerve with the 0.9 cup as compared to the nerve with the 0.3 cup.
Grading is done by cup to disc ratio. (the depressed area in the center of the nerve) to the entire diameter of the optic nerve.
Vision with glaucoma
Vision with Glaucoma
The object you focus will appear clear -with an area to the side of your focus which will be blurry.
If you gaze at the blurry area it becomes crisp and now a different area on side will become blurry.
It is difficult to perceive early peripheral visual field defects .
Hence glaucoma is called the ‘ sneak thief of vision ’.
Primary open-angle glaucoma is the most common type.
Slow aqueous drainage leads to chronically elevated intraocular pressures.
Patients are asymptomatic and may suffer substantial visual field loss before consulting a physician.
Causes are multifactorial and polygenic.
Primary angle closure glaucoma (acute glaucoma) occurs much more rapidly when the flow of fluid inside the eye cannot pass through the pupil,
causing a rapid rise in pressure inside the eye.
Characterised by pain, redness and reduced vision.
The pupil of the eye is dilated.
The cornea is usually swollen, causing the haloes round lights and blurring of vision
Glaucoma Management :
Intraocular pressure-lowering medications (local and systemic, eg, latanoprost and brimonidine)
Argon laser trabeculoplasty
Intraocular surgery +/- antimetabolites
Ciliary body destructive procedures
Leading cause of visual impairment
Treatment: eyeglasses, contact lenses, laser refractive surgery
Astigmatism (visual distortion)
Presbyopia ( ability to focus at near objects)
Begins after age 40
Caused by gradual hardening of the lens and decreased muscular effectiveness of the ciliary body
Each line of the eye chart is assigned a notation in the form of a fraction that represents your visual acuity.
The numerator is the distance in feet the patient is from the eye chart.
The denominator represents the distance an eye with “normal” vision can read the same line.
Interpreting the numbers is simple. If you can read the 20/40 line, you’re able to see at 20 feet what a normal eye could see at 40.
ANTERIOR ISCHEMIC OPTIC NEUROPATHY
Microvascular occlusion of the blood supply to the optic nerve
Due to atherosclerotic vascular disease or inflammation (temporal arteritis)
Results in acute vision or field loss
ANTERIOR ISCHEMIC OPTIC NEUROPATHY Pallid swelling of the optic nerve head in a patient with anterior ischemic optic neuropathy.
Tear production decreases with age
Characteristics: redness, foreign body sensation, and reflex tearing
Management: replacement of tears (artificial tears during daytime and ointment at bedtime)
Temporary or permanent punctal plugs may retard tear egress in severe cases.
Common among older adults
Gradual loss of elasticity and tensile strength that develops with age
Blepharochalasis (drooping of the brow) and blepharoptosis (drooping of the eyelid) may cause cosmetic deformity and, if severe, may impair vision.
Lid ectropion (eversion) or entropion (inversion) may cause discomfort.
HERPES ZOSTER OPHTHALMICUS
Painful reactivation of varicella zoster virus
Affecting the ophthalmic division of the trigeminal nerve
Hutchinson’s sign: lesions on the tip of the nose
Oral acyclovir may shorten the course.
Post-herpetic neuralgia may be debilitating; treat with local ointments (capsaicin, lidocaine) or systemic medications (corticosteroids, tricyclic antidepressants).
Herpes zoster Ophthalmicus
Available to patients with acuity < 20/60
Improved lighting and selection of reading material with bold, enlarged fonts and accentuated black-on-white contrast