Keratometry, biometry, and prediction of intraocular lens power in adult tigers (Panthera tigris)

OBJECTIVE To calculate the necessary pseudophakic intraocular lens (IOL) power to approximate emmetropia in adult tigers. ANIMALS 17 clinically normal adult tigers. PROCEDURES y33 eyes of 17 clinically normal adult tigers underwent routine ophthalmic examination and B-scan ultrasonography while anesthetized for unrelated procedures. Specific ultrasound data (globe measurements and corneal curvature) and estimated postoperative IOL positions were utilized to calculate predicted IOL power by use of Retzlaff and Binkhorst theoretical formulas. Applanation tonometry and refraction were also performed. RESULTS Mean +/- SD axial globe length was 29.36 +/- 0.82 mm, preoperative anterior chamber depth was 7.00 +/- 0.74 mm, and crystalline lens thickness was 8.72 +/- 0.56 mm. Mean net refractive error (n = 33 eyes) was +0.27 +/- 0.30 diopters (D). By use of the Retzlaff formula, mean predicted IOL power for the postoperative anterior chamber depth (PACD), PACD - 2 mm, and PACD + 2 mm was 43.72 +/- 4.84 D, 37.62 +/- 4.19 D, and 51.57 +/- 5.72 D, respectively. By use of the Binkhorst equation, these values were 45.11 +/- 4.91 D, 38.84 +/- 4.25 D, and 53.18 +/- 5.81 D, respectively. Mean intraocular pressure for all eyes was 14.7 +/- 2.69 mm Hg.