Intraocular lens prediction and oculometric harmony. With special reference to skew ratios between axial length and corneal curvature radius.
The oculometric features have been analysed in two groups of cataract patients, each comprising 30 subjects. All had undergone ECCE and insertion of biconvex Rayner 2 Superflex posterior chamber IOL. Using Binkhorst and SRK II routinely, the groups were given by a good fit between methods (discrepancy between emmetropia predictions numerically < 1 D) and a poor fit (actual discrepancy range 1.6-4.1 D, all with the same sign, the lower values being predicted by Binkhorst). A certain overlapping between groups was found regarding axial length and corneal curvature radius, the ranges being 21.5-25.1/22.7-29.9 mm and 7.3-8.5/7.2-8.1 mm, respectively. In contrast there was no overlapping regarding the ratio between axial length and corneal curvature radius; the ranges were 2.80-3.05 and 3.06-3.90 in the two groups. Evaluating the actual prediction errors by the two methods (follow-up after at least 4 months), they did not primarily pertain to very short or very long eyes, as usually advanced. Skew ratios between axial length and corneal curvature appeared more decisive. Possible implications for the current IOL prediction formulas, including the newer generations, are discussed.
Fich
M
M
Eye Department, Centralsygehuset, Hillerød, Denmark.
Fledelius
H C
HC
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002387:Cataract Extraction; D003315:Cornea / Q000033:anatomy & histology*; D005123:Eye / Q000033:anatomy & histology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D055095:Optics and Photonics; D011237:Predictive Value of Tests