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Abhijit Sinha Roy, Rohit Shetty, Natasha Pahuja, Roshan T, Rashmi Deshmukh, Mathew Francis; Outcomes of spatial modulation of UVA beam intensity to minimize delivered UVA energy in corneal crosslinking. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4345.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the performance of different customized corneal crosslinking (CXL) methods
Four different customized CXL methods were evaluated in keratoconic eyes. These methods were as follows: (a) uniform intensity UVA beam (9 mW/cm2) for 10 minutes; (b) sector based UVA irradiation (Figure 1B); (c) concentric rings of UVA beam intensity centered at the steepest curvature of anterior axial map (Figure 1A); (d) same as (c) but centered at the steepest curvature of anterior tangential map. Peak UVA energy density in (b) and (c) (as well as (d)) didn’t exceed 15.0 and 10.8 J/cm2, respectively. 0.1% solution riboflavin solution was applied after epithelium removal. Corneal tomography and visual acuity was assessed before and 6 months after CXL.
The number of eyes in each treatment group was 12 to 14 eyes. Only one eye per patients was included in the analyses. Average and peak energy density was lowest in method (d) [2.424±0.068 J/cm2] and highest in (b) [8.316±0.392 J/cm2] (p<0.001). Treated area was lowest in method (d) [32.699±3.554 mm2] and highest in method (a) [63.63±0.00 mm2] (p<0.001). Maximum curvature decreased by a mean of 1.71, 1.51, 0.44 and 1.31D in method (a), (b), (c) and (d), respectively. Decrease in Pentacam overall deviation index (BAD-D) and cone location magnitude index was similar between all the methods (p>0.05). Decrease in curvature was similar among methods (a), (b) and (c) (p<0.05). Therefore, all curvature indices were normalized with the average UVA energy density and re-analyzed. Method (d) had the greatest decrease in curvature per unit energy dose to the cornea (p<0.05). Improvement in UDVA (0.081±0.056) and CDVA (0.041±0.026) per unit energy density was greatest in method (d) but required greater sample size for significance (p>0.05).
Method (d) appeared to provide maximum flattening and improvement in visual acuity. Further studies with larger sample size are needed to validate the findings of this pilot study.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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