Rs. Kalski et al., INTRAOCULAR-LENS POWER CALCULATION FOR CATARACT-SURGERY AFTER PHOTOREFRACTIVE KERATECTOMY FOR HIGH MYOPIA, Journal of refractive surgery, 13(4), 1997, pp. 362-366
OBJECTIVE: To assess intraocular lens (IOL) power calculations in pati
ents undergoing cataract surgery after excimer laser photorefractive k
eratectomy (PRK) for myopia. METHODS: Four eyes of two patients underw
ent phacoemulsification with IOL implantation after PRK for myopia. Th
e estimated refractive error that would have been induced had the IOL
predicted for emmetropia been implanted was calculated using SRK-II, S
RK/T, Holladay, and Binkhorst formulas. Manual keratometry and videoke
ratography-simulated keratometry values measured before surgery were u
sed. Keratometry values calculated by subtracting the refractive chang
e induced by the excimer laser PRK from the manual keratometry or vide
okeratography-simulated keratometry values measured before PRK were al
so used. Both spectacle and corneal plane calculations were performed.
RESULTS: Manual keratometry and videokeratography-simulated keratomet
ry values underpredicted the IOL power. Corneal plane manual or videok
eratography refraction-derived keratometry calculations were most accu
rate using the SRK/T formula, while spectacle plane calculations were
most accurate using the SRK-II formula. In both methods the calculated
refractive error was within 0.52 diopters (D) for the emmetropic lens
power predicted. Statistical analysis was not performed. CONCLUSIONS:
Refraction-derived keratometric values provided the most accuracy in
calculating IOL powers. Our results suggest the SRK/T formula was the
most accurate for corneal plane calculations, while the SRK-II formula
was the most accurate for spectacle plane calculations.