Relationships between preoperative astigmatism and corneal optical power, axial length, intraocular pressure, gender, and patient age.
BACKGROUND
Preoperative astigmatism is likely to influence the outcome of cataract surgery, but it is only rarely considered in studies of cataract surgery outcomes.


METHODS
As part of a population-based study of 5878 consecutive cataract surgeries performed from 1986 through 1990, I studied the relationship between preoperative astigmatism and corneal shape, axial length, intraocular pressure, gender, and age.


RESULTS
The men had more against-the-rule astigmatism than the women, and the preoperative astigmatism shifted for both genders toward against-the-rule with age. Long eyes tended to have more with-the-rule astigmatism. Also, astigmatism deviated more from normal in both long and short eyes, and the with-the-rule astigmatism decreased with increasing intraocular pressure. Finally, I found that a second-degree polynomial model better described the relation between the axial lengths and keratometric powers better than a linear one.


CONCLUSIONS
Axial length is related to the direction and amount of astigmatism. Because in the present study a second-degree polynomial described the relationship between the axial lengths and keratometric powers better than a simple linear regression, a polynomial model also probably should be used for calculating the power of the intraocular lens to be inserted.
Ninn-Pedersen
K
K
Department of Ophthalmology, Lund University Hospital, Sweden.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D001251:Astigmatism / Q000209:etiology*; D002387:Cataract Extraction; D003315:Cornea / Q000033:anatomy & histology*; D005123:Eye / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012189:Retrospective Studies; D012737:Sex Factors; D014792:Visual Acuity