Intraocular lens calculation. An evaluation of Binkhorst and SRK estimates in 100 consecutive cataract extractions with 3M type 78 anterior chamber lens implantation.
Intraocular lens power prediction and final astigmatism were evaluated in 100 consecutive cataract patients (age 57-92 years, mainly with intracapsular extraction) 4-13 months after insertion of a 3M type 78 anterior chamber lens. The analysis was based on refractive recordings from the referring ophthalmologists who took care of post-operative controls. Ninety-two patients were accepted for the study. A Sonometrics DBR 400 ultrasound equipment and a Haag-Streit keratometer had been used for measuring eye length and corneal power, the Binkhorst programme and SRK formula for selecting IOL power, resulting in an IOL range of +12 to +23 D. Mainly, low myopia was intended. Nearly 50% fell within 0.5 D from predicted value; 90% were within +/- 1.5 D, by both calculating methods. SRK predictions appeared unaffected by eye size, while axial length (x) significantly influenced Binkhorst prediction (y): y = 8.08-0.35x (r = -0.40), the deviation being most marked in very short eyes. For eyes of midsize the two methods did not differ. Regarding astigmatism, 3 patients ended with values above 3D. In 83% it was less than 2D. Eighty per cent obtained a visual acuity of 0.5 or better. All things considered we feel that the calculation procedure should be standard when performing cataract surgery with IOL implantation.
Fledelius
H C
HC
Department of Ophthalmology, Frederiksborg County Hospital, Hillerød, Denmark.
Alsbirk
P H
PH
Goldschmidt
E
E
D000368:Aged; D000867:Anterior Chamber; D003315:Cornea / Q000033:anatomy & histology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D014463:Ultrasonography; D014792:Visual Acuity