Intraocular Lens Power Calculation After Corneal Refractive Surgery: Using Corneal Height in Anterior Segment OCT
Narrative Responses:
Purpose
To investigate the feasibility of the intraocular lens power calculation method using measured corneal height (CH) from anterior segment optical coherence topography(AS-OCT) after corneal refractive surgery.
Methods
Medical records of 30 eyes in 23 patients who had received corneal refractive surgery and underwent cataract operation were retrospectively analyzed. Estimated IOL position(ACDest) was calculated from an axial length(AL), corneal radius(K) and Preal which achieved emmetropia from postoperative manifest spherical equivalent. CH was measured with AS-OCT and was applied to SRK/T for measured IOL position(ACDm). Converted IOL power(Pconv) was acquired from the linearly regressedACDm,ALand K. The accuracy of Pconv was compared with Preal. ACDm was compared with ACDest estimated from The adjusted K using Koch, Savini method or from mean power map in Orbscan.
Results
The mean CH, ACDest, ACDm were 3.71±0.23, 7.74±1.09, 5.78±0.26 mm. The linear regression formula between ACDm and ACDest was ‘ACDest = 1.673 × ACDm – 1.934’ (p=0.032, R=0.394). The mean difference between Pconv and Preal was 0.24±1.53 D. The percentages of eyes within ±0.5D, ±1.0D, ±1.5D, ±2.0D of the refractive errors, which were calculated from Pconv, were 33.3, 66.3, 86.7, 93.3% respectively. ACDest estimated from the adjusted K did not show statistically significant correlation with ACDm.
Conclusion
IOL power calculation method using corneal height measured by AS-OCT may be an another alternative option in patients who need cataract surgery and have undergone prior corneal refractive surgery.