The relationship between changes in corneal posterior surface astigmatism and unexpected changes in the residual astigmatism, determined by objective and subjective refraction, after routine cataract surgery

Session Details

Session Title: Toric IOLs & Lens Power Calculations

Session Date/Time: Sunday 15/09/2019 | 08:00-10:00

Paper Time: 09:26

Venue: Free Paper Forum: Podium 3

First Author: : L.Tutchenko UKRAINE

Co Author(s): :    S. Patel   O. Voytsekhivskyy   M. Skovron   O. Horak                    

Abstract Details

Purpose:

To explore the significance of any association between changes in unexpected residual refractive astigmatism and any changes in corneal posterior surface astigmatism following uneventful routine phacoemulsification in patients with clear corneas with unremarkable surface irregularities.

Setting:

Department of Ophthalmology, Shupyk National Medical Academy of Postgraduate Education, Kyiv, Ukraine; Kyiv City Clinical Ophthalmological Hospital “Eye Microsurgery Center”, Ukraine.

Methods:

Astigmatism was evaluated by objective (RA) and subjective refraction (SA) and at the corneal posterior surface (CPS) using Orbscan II (Bausch & Lomb) over central 3mm[A] and 5mm[B] optical zones at one, two & three months after phacoemulsification with one type of nontoric IOL implantation. Data were subjected to vector analysis to determine the actual change in astigmatism (power & axis) for the refractive and Orbscan II findings. Surgery was performed under topical anaesthesia (2.2mm incision at 12o’clock), postop injection of dexamethasone (subconjunctival) and betamethasone (parabulbar), topical levofloxacin, oftan-dexamethason, indomethacin, dexpanthenol, trehalose and hyaluronic acid.

Results:

In 103 patients (1eye/patient where actual change in residual astigmatism ≥0.50DC), between (i)1&2 and (ii)2&3 months postop, in plus cylinder format, there was a significant linear relationship between: 1) Corresponding changes in RA(y) and CPS astigmatic power(x) over [A] at (i)y=0.090x+0.714(r=0.325,n=52,p=0.019) and (ii)y=0.118x+0.681(r=0.467 n=24, p=0.021); over [B] at (i)y=0.061x+0.709(r=0.305,n=52,p=0.028). 2) Corresponding changes in sine of RA axis(y1) and sine of CPS axis (x1) over [A] at (i) y1=0.745-0.303x1 (r=0.299,n=52,p=0.031). 3) Corresponding change in SA(y) and CPS astigmatic power(x) over [A] at (i) y=0.072x+0.545(r=0.510,n=19,p=0.026).

Conclusions:

Astigmatic changes at the posterior surface of the cornea, within the central optical zone, are related to unexpected changes in refractive astigmatism following uneventful routine phacoemulsification.

Financial Disclosure:

None