PATHOLOGY

f ¼ focal length (cm), r ¼ radius of curvature; central ray goes through center of curvature

Convex mirror: has minus power, image is virtual, erect, minified (e.g., rear view mirror, cornea)

Concave mirror: has plus power (e.g., shaving mirror). If object is closer than 1/2 of radius of curvature, then image is virtual, magnified, and upright. If object is between 1/2 of the radius and the center of curvature, then the image is real, minified, and

inverted.

D

ANGULAR MAGNIFICATION: M ¼ 4

M ¼ magnification, reference distance ¼ 25 cm

TELESCOPE MAGNIFICATION (angular): M ¼ Deyepiece

Dobjective

TELESCOPE ACCOMMODATION: ¼ normal accommodation (telescope magnification)2

1.Astronomical: 2 plus lenses; length is 1/Deyepiece þ 1/Dobjective (longer length; gives inverted image; e.g., lensometer)

2.Galilean: minus eyepiece with plus objective; length is 1/Deyepiece – 1/Dobjective (shorter length; gives an upright image; e.g., microscope, loupes, or a corrected aphakic patient whose 12.5 D error lens is the eyepiece 10 D spectacles objective lens ¼ 1.25 or 25% magnification)

VISUAL ACUITY 20/20 vision is equivalent to 1 minute of arc or 30 cycles per degree of contrast.

Snellen’s optotypes: standard visual angle of 1 minute of arc; numerator corresponds to the testing distance; denominator corresponds to the distance at which the test letters subtend an angle of 5 minutes of arc.

Pathology

FIXATION Use alcohol for tissues containing water-soluble crystals and formalin for protein.

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20 GENERAL TOPICS IN OPHTHALMOLOGY

GROSS PATHOLOGY OF GLOBES Orient posteriorly to see the ON and four vortex veins with superior oblique muscle (SO) insertion superotemporally and inferior oblique muscle (IO) inferotemporally. Dissect in the meridian of interest: vertical through surgical wounds, horizontal through macula, or in the meridian of a tumor. Start the cut 2 mm lateral to ON, and exit 2 mm inside limbus.

HISTOLOGIC STAINS AND CLINICAL USES See Table 1–4.

IMMUNOLOGIC STAINS See Table 1–5.

INTERMEDIATE FILAMENTS See Table 1–6.

TABLE 1–4

Selected Histologic Stains and Clinical Uses

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INTRACELLULAR BODIES Russell’s bodies—represent stored Ig in plasma cells that are antibody (Ab) factories seen with chronic inflammation. Dutcher bodies—represent Ig in lymphocytes.

INTRACELLULAR INCLUSIONS (Mnemonic: Give your HEN a CBC). Herpes viruses have eosinophlic intranuclear inclusions versus chlamydia, which has basophilic cytoplasmic inclusions.

TABLE 1–6

Intermediate Filaments

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22 GENERAL TOPICS IN OPHTHALMOLOGY

TABLE 1–7

Selected Culture Mediums

NAD, nicotinamide adenine dinucleotide.

SIGNS OF MALIGNANCY Atypia (single-cell abnormality), dysplasia (abnormal structure among cells), faulty maturation, loss of polarity

SKIN PATHOLOGY TERMINOLOGY

Acantholysis: separation of epidermal cells; rapid growth, as in inverted follicular keratosis (IFK)

Acanthosis: thickening of squamous, prickle cell layer

Dyskeratosis: intraepithelial keratinization (mnemonic: ‘‘dys don’t belong here’’).

Hyperkeratosis: thickening of keratin layer; denotes rapid tissue growth

Parakeratosis: absence of granular layer with nuclei in keratin; immature tissue; rapid growth

Pseudoepitheliomatous hyperplasia (PEH): reactive process; invasive acanthosis

CULTURE MEDIUMS See Table 1–7.

Pregnancy

NORMAL OCULAR CHANGES Decreased IOP from enhanced uveoscleral outflow and lowered episcleral venous pressure (EVP); minimal corneal edema may lead to refractive changes and contact lens intolerance.

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