Analysis Of Vault Prediction In Phakic Implantable Phakic Collamer Lenses: Manufacturer’S Calculator Vs Theoretical Formulae Vs Clinical Practice

 Implantable Collamer Phakic (ICL) intraocular lens sizing calculations are necessary to avoid complications associated to inadequate sizing. Historically numerous authors have tried to create new formulas that solve calculation problems and provide higher reliability. In addition, in recent years the appearance of new equipment, parameters and formulas have led to significant progress. The purpose of this paper is to compare ICL sizing and vault achievements according to manufacturer’s method and other methods

Clínica Rementería. Madrid.

43 eyes of 24 patients with EVO Visian ICL implanted, with at least 1 year of follow-up, were analyzed. The analyzed variables were: WTW (White to White), ACD (Anterior Chamber Depth), ACW-ATA (Anterior Chamber Width-Angle to Angle), CLR (Crystalline Lens Rise), ICL size, vault measured at 1 week and 1 year after surgery. ICL size and power was calculated with manufacture’s webpage OCOS, selecting the lens closest to emmetropia. Final ICL size was decided by surgeon according to OCOS, to the relationship among variables and to surgeon’s own experience. ICL size and vault prediction by Nakamura-2 was calculated using his own published formulas. 

OCOS indicates to implant a 13,2mm size ICL in 46,51%, and 12,6mm in 44,19% of cases; 12,1 and 13,7 mm was only indicated in 4,65% of cases. Implanted ICL sizes distribution was 53,49% in 12,6mm, 41,86% of cases in 13.2mm; 4,65% in 12,1mm . There was an agreement in 86% of cases between the lens size calculated by OCOS and the one implanted. In 14% of cases a smaller size ICL was implanted. According to Nakamura 2, 13,2mm ICL was the most suggested in 67,44% of cases; and 12,6mm in 27,91% of cases. Nakamura-2 formula indicated a bigger ICL size in 32,56% of cases and a smaller size in 18,60% of cases.

The mean vault achieved in lenses implanted with agreement between OCOS and surgeon’s final decision was 562,19±222,15µm.

Sizing calculation with OCOS according to WTW and ACD is a good indicator with 86% success rate. Vault prediction with OCOS seems to be the most predictable compared with other alternative methods. Nakamura-2 and Igarashi obtained lower indices according to the lens implanted. ICL sizzing according WTW and ACD, using the manufacturer’s algorithm seems to be the most predictable method compared to other algorithms using other variables. The surgeon’s expertise also has a high importance in the final ICL size election.