Chapter 9

Each type of phaco procedure has subtle distinctions that may lead to inconsistent surgical outcomes. Each procedure has potential hurdles that may lead to complicated outcomes. This chapter and Chapters 10 to 14 define each procedure and examine the steps leading to successful outcomes and the pitfalls leading to complications.

CATARACTOGENESIS

The classification of cataracts is artificial but useful to categorize particular cataract qualities. This allows the surgeon to plan effective surgery based on the expected cataract qualities.

The terms congenital and developmental cataract encompass lens opacities noted at birth and during infancy, respectively. Juvenile cataract denotes onset during the period of childhood to adolescence. Pre-senile refers to onset between early adulthood and age 60 years, with the term senile cataract used for cataracts that develop thereafter. Cataracts developing during the juvenile period and the presenile period are often due to ocular disease, trauma, or the use of steroids. These cataracts may indicate the carrier state or early phase of genetic disease.¹

Biochemical changes that consistently occur in cataracts include increased water content, loss of potassium, increased calcium, increased oxygen consumption, decreased glutathione, and decreased ascorbic acid. Many of these changes may be the result, rather than the cause, of cataracts.²

Histopathologic and ultrastructure analysis are seldom suggestive of a specific etiology, showing changes common to all subcapsular, cortical, or nuclear sclerotic cataracts.¹

The following outline is an overview of the major types and causes of cataracts:

A. Major categories of congenital cataracts²

1. Remnants of the tunica vasculosa lentis

a. In the iris these are observed as pigmented pupillary membranes attached at the collarette.

b. In the anterior capsule they are a single or group of spots, which may be pigmented and are attached to the anterior capsule.

c. In the posterior capsule they are Mittendorf dots or white spots attached to the posterior capsule just inferior and nasal to the posterior pole of the lens. They rarely affect vision.

2. Polar: These cataracts may be either anterior or posterior and affect the subcapsular cortex and lens capsule. They may be either hereditary or secondary to intrauterine inflammatory processes. They may have a significant effect on vision depending on size and location.

3. Sutural: These cataracts involve the Y sutures. Often hereditary, they rarely affect sight.

4. Capsular: These cataracts are a small opacification in the anterior epithelium and lens capsule, sparing the cortex. They may protrude into the anterior chamber. They rarely affect vision.

5. Zonular: These cataracts involve opacification in the outer fetal and inner adult nucleus. They appear as fine white dots, haze, or linear spokes. They are always bilateral and are due to hereditary or other noxious stimuli during pregnancy. They are likely to affect vision.

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