Angle Kappa And Astigmatism After Phacoemulsification And Implantation Of Spherical And Aspheric Iols.

To determine the significance of any association between angle kappa (Κ°) and changes in astigmatism afterphacoemulsification.

Kyiv City Clinical Ophthalmological Hospital, Eye Microsurgery Center, Kyiv, Ukraine

Κ° (estimated using Orbscan II, Bausch&Lomb) and refraction were checked at 1,2 &3 months following unremarkable phacoemulsification in eyes implanted with either spherical (group I,SA60AT,Alcon) or aspheric (group II,SN60WF,Alcon) non-toric IOLs. Refraction data (objective and subjective refraction) were subjected to vector analysis to determine the actual change induced over the periods 1-to-2 & 2-to-3 months postop. All surgeries were 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.

Mean(n,±s.d) Κ in group I was; for 1&2 months,6.40°(38,±3.25°)&5.92°(38,±1.79°); at 2&3 months, 5.62°(23,±1.68°)&5.75°(23,±1.83°). In group II,6.51°(45,±2.68°)&6.26°(45, ±2.33°);6.06°(23,±1.42°)&5.84°(23,±1.43°). Differences in Κ were not significant. Significant correlations were revealed between change in Κ(ΔK=Κ at 1month[X]–Κ at 2months) and X [I,ΔK=0.668-3.794X,(r=0.812,n=38,p=<0.01),IIΔ =0.263X 1.462,(r=0.494,n=45,p=<0.01)] but not over2&3 months. In group II, change in Κ between 2&3 months(X₁) and the vector describing the change in astigmatism (ΔJ₄₅) revealed at 3 months by refraction was significant. This association is best described as ΔJ₄₅=0.086X₁–0.063 (r=0.378,n=26,p=0.020). 

Previous investigators have demonstrated that angle kappa could be associated with unexpected changes in astigmatism after implantation of toric IOLs or after routine corneal refractive surgery. Changes in angle kappa can occur after routine phacoemulsification in individual cases these are loosely associated with changes astigmatism. However, the relationship between the induced change in astigmatism resulting from a change in Κ is not straightforward.