problems with perception

• This defect prevents light rays from converging into a single focus on the retina.

  refractive errors
• causes of refractive errors

  defects are a result of irregularities of the corneal curvature, the focusing power of the lens, or the length of the eye
• myopia


  nearsightness
• hyperopia


  farsightedness
• asymmetric focus of light rays on the retina

  astigmatism
• inability of the lens to change curvature in order to focus on near objects

  presbyopia
• (inability of the eyes to focus in the same direction.)

  strabismus
• surgical procedure used to correct myopia and astigmatism

  radial keratotomy
• test for IOP


  tonometry
• normal IOP


  10-21 mmHg
• study the angle of the anterior chamber of the eye

  gonioscopy
• TYPE OF SURGERY - excision of a small portion of the iris whereby aqueous humor can bypass the pupil; treatment of choice. Typically a laser procedure

  Peripheral iridectomy
• TYPE OF SURGERY - partial-thickness scleral resection with small part of trabecular meshwork removed and iridectomy. Necessary if peripheral anterior adhesions (synechiae) have developed due to repeated glaucoma attacks.

  Trabeculectomy
• TYPE OF SURGERY —multiple tiny laser incisions to iris to create openings for aqueous flow; may be repeated.

  Laser iridotomy
• 1. types of cataract

  senile - commonly occurs with aging. 2. Congenital cataract—occurs at birth. 3. Traumatic cataract—occurs after injury. 4. Aphakia—absence of crystalline lens.
• to determine the scope of the visual fifield (normal with cataract)

  perimetry
• —the lens as well as the capsule are removed through a small incision

  Intracapsular extraction
• the lens capsule is incised and the nucleus, cortex, and anterior capsule are extracted.

  Extracapsular extraction
• used to remove the lens. A pencil-like instrument with a metal tip is supercooled (–35° C), then touched to the exposed lens, freezing to it so the lens is easily lifted

  cryosurgery
• an option for those who do not receive IOL implants

  Extended-wear contact lens
• Detachment of the sensory area of the retina (rods and cones) from the pigmented epithelium of the retina

  retinal detachment
• shows gray or opaque retina. The retina is normally transparent. Slit-lamp examination and three-mirror gonioscopy magnify the lesion.

  Indirect ophthalmoscopy
• photocoagulation - a light beam (either laser or xenon arc) is passed through the pupil, causing a small burn and producing an exudate between the pigment epithelium and retina
• 2. Electrodiathermy —an electrode needle is passed through the sclera to allow subretinal fluid to escape. An exudate forms from the pigment epithelium and
• 3. Cryosurgery or retinal cryopexy—a supercooled probe is touched to the sclera, causing minimal damage; as a result of scarring, the pigment epithelium adheres to the retina
• Scleral buckling —a technique whereby the sclera is shortened to allow a buckling to occur, which forces the pigment epithelium closer to the retina (often accompanied
• Conjunctivitis - Inflammation or infection of the bulbar (covering the sclera and cornea) or palpebral (covering inside lids) conjunctiva. “pink eye” usually refers to infectious conjunc