cataracts

Wavefront-guided or "custom" laser

"Imprints" patient's custom refraction Theoretically removes aberrations in cornea Higher chance of reaching refractive goal in low/moderate myopes -can be used for PRK/LASEK/LASIK

Cataract Treatment indications

- vision has decreased to 20/40 or worse -decreased vision is having negative effect on activities of daily living

INTRASTROMAL CORNEAL RINGS (INTACS)

-Circular rings of polymethylmethacrylate (PMMA) placed in mid peripheral stroma -Treats low myopia -Removable/exchangeable

PHAKIC INTRAOCULAR LENSES (IOLs)

-IOL inserted into eye with natural lens still in place -Allows for accommodation -Typically used in younger high myopes -Avoids ablation of cornea -Removable -Small risk of cataract and iritis

INTRAOCULAR SURGERY

-Improved technology and techniques allow for relatively safe "elective" intraocular surgery 1) Phakic IOL 2) Clear lens extraction 3) Accommodative IOL

RADIAL KERATOTOMY (RK)

-Multiple radial cuts into corneal stroma to correct mild to moderate myopia -No longer the most popular, safest, or most stable refractive procedure -Irregular astigmatism, Glare, Wound dehiscence

MONOVISION

-One eye (dominant) set for distance and one eye set for near or intermediate (as shown) -Can be used in a variety of refractive procedures

NATURAL LENS REPLACEMENT indications

-Replacing noncataractous crystalline lens with IOL for refractive purpose 1) Not a good photoablative candidate 2) Cornea too thin, too flat, too steep 3) High myopia/hyperopia

Excimer ("excited dimer") laser

-Used for PRK, LASEK, LASIK

lens changes overtime Ciliary body/lens changes

-Yellows: may affect color discrimination -Opacifies: cataract -Hardens: nuclear sclerosis -Loses accommodative ability: presbyopia

Causes of Cataract

-age (most common over the age of 65) -diabetes -family history -previous surgery or injury -nutritional deficiencies -oral prednisone

Presbyopia

-age-related loss of lens flexibility, causing reduced near vision -Loss of accommodation with age -Manifests in early 40s -Cannot be halted or mitigated with refractive surgery

misconceptions

-cataract is not a film over the eye -it is not a cancer -it is not caused by straining the eye -it is not spread from one eye to the other -it is not a cause of irreversible blindness

Cataract surgery process

-outpatient/awake/IV valium -pupil dilation drops 2hrs prior -local anesthetic(local injection or topical drops) -usually done through small sutureless incision (approximately 3mm) -usually removed with ultrasound instrument called phacoemulsification -intraocular implant lens placed in the eye to replace natural lens that was removed as the cataract -usually 90% recovered within 5-7 days -distance prescription typically reduced with intraocular lens

after cartaract tx cloudiness may occur months to years after surgery due to what

-posterior capsule clouds up 10-30% of the time after surgery -laser used to open a hole through the posterior capsule

Refractive Surgerys

-to primarily reduce distance prescription 1) Lasik 2) PRK 3) Phakic IOL 4) Clear lens extraction monovision or presbyopic IOL can correct near vision

PHOTOREFRACTIVE KERATECTOMY (PRK): PROCEDURE

1) Alcohol placed to loosen epithelium 2) Central epithelium debrided 3) Laser ablation 4) Epithelium grows back from periphery under bandage contact lens

LASER IN SITU KERATOMILEUSIS (LASIK): PROCEDURE

1) Suction ring stabilizes globe 2) Microkeratome creates thin stromal flap with a hinge 3) Flap reflected back 4) Laser ablation sculpts cornea 5) Stromal flap replaced

Signs and Symptoms of cataracts

1) painless gradual loss of vision in one or both eyes 2) reduced visual acuity on exam 3) reduced red reflex 4) discoloration of lens of eye ranging from green to brown to white

Risks of cataract surgery

1) vision loss-retinal detachment 2) loss of eye-corneal edema 3) infection-ptosis 4) hemorrhage-diplopia 5) glaucoma edema-cystoid macular

PRK: ADVANTAGES AND DISADVANTAGES

Advantages 1) No corneal flap complications 2) Long-term stability 3) Can perform on thin cornea Disadvantages 1) More patient discomfort 2) Inconvenience: usually done one eye at a time 3) Slightly higher risk of infection 4) Risk of haze (mitomycin C may minimize) 5) Glare/halos

NATURAL LENS REPLACEMENT: ADVANTAGES AND DISADVANTAGES

Advantages 1) Same procedure as cataract surgery - same provider can do 2) Avoids risks of flap creation and corneal ablation 3) Corrects high degree of myopia/hyperopia Disadvantages 1) Endophthalmitis 2) hemorrhage 3) retinal detachment 4) Patient expectations

LASIK: ADVANTAGES AND DISADVANTAGES

Advantages: 1) Little discomfort 2) Fast visual recovery 3) Long-term stability Disadvantages 1) Thin corneas not good candidates 2) Flap complications 3) Glare/halos 4) Diffuse lamellar keratitis (DLK)

Conventional laser

Laser program "imprints" standard refraction onto cornea -can be used for PRK/LASEK/LASIK

Astigmatism

Uneven curvature of cornea Causes separate areas of focus and consequent blurring

what can be corrected by new cartaract lens

astigmatism and presbyopia

Hyperopia

farsightedness Renders refractive surgery less predictable, requires longer to stabilize (PRK and Lasik)

Myopia

nearsightedness (not being able to see far) Severity is related to success of refractive surgery (PRK and Lasik)

phacoemulsification

ultrasound instrument used for cataract threatment