Assessing the likely effect of posterior corneal curvature on Toric IOL calculation for IOLs of 2.50 D or greater cylinder power

LaHood, Benjamin R., Goggin, Michael, and Esterman, Adrian (2017) Assessing the likely effect of posterior corneal curvature on Toric IOL calculation for IOLs of 2.50 D or greater cylinder power. Journal of Refractive Surgery, 33 (11). pp. 730-734.

[img] PDF (Published Version) - Published Version
Restricted to Repository staff only

View at Publisher Website: http://dx.doi.org/10.3928/1081597X-20170...
17


Abstract

Purpose: To establish whether average refractive overcorrection or undercorrection of corneal astigmatism based on the orientation (rule) of the astigmatism occurs if toric intraocular lenses (IOLs) are calculated on the basis of anterior corneal measurements in eyes requiring toric IOL cylinder power of 2.50 diopters (D) or greater.

Methods: One hundred thirteen consecutive eyes with anterior corneal keratometric astigmatism requiring IOL cylinder power of 2.50 D or greater underwent phacoemulsification with IOL powers calculated using anterior corneal curvature data alone. Eyes were grouped as either "with-the-rule" (WTR) or "against-the-rule" (ATR) on the basis of the steep anterior corneal meridian. Targeted and achieved astigmatic outcomes were compared. The main outcome measure was the postoperative refractive astigmatic prediction error.

Results: A mean overcorrection occurred in anterior WTR eyes of 0.16 +/- 0.57 D and a mean undercorrection of ATR eyes of -0.14 +/- 0.53 D. These were significantly different from the ideal value of zero (WTR: P = .04, ATR: P = .05). Although statistically significant, the effect sizes of these prediction errors were 0.40 for WTR and 0.36 for ATR and the error values fell below a clinically significant value of 0.25 D.

Conclusions: In eyes requiring toric IOLs of cylinder power 2.50 D or greater, an overcorrection occurs in anterior WTR eyes and an undercorrection in ATR eyes. This probable posterior corneal astigmatism effect is not clinically significant. IOL cylinder powers are sufficiently accurately calculated using unadjusted anterior keratometry values in these eyes.

Item ID: 51836
Item Type: Article (Research - C1)
ISSN: 1938-2391
Date Deposited: 20 Dec 2017 07:45
FoR Codes: 32 BIOMEDICAL AND CLINICAL SCIENCES > 3212 Ophthalmology and optometry > 321201 Ophthalmology @ 100%
SEO Codes: 92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920107 Hearing, Vision, Speech and Their Disorders @ 100%
More Statistics

Actions (Repository Staff Only)

Item Control Page Item Control Page