Posters

Results of simultaneous wavefront-guided photorefractive keratectomy with accelerated corneal collagen cross-linking in management of mild to moderate keratoconus

Poster Details

First Author: P.Gupta INDIA

Co Author(s):    J. Reddy   V. Bhandari   K. Siddharthan        

Abstract Details

Purpose:

To evaluate visual, refractive, topographic & corneal higher order aberrations outcome after simultaneous wavefront guided photorefractive keratectomy ( PRK ) with accelerated corneal collagen cross linking (C3R) in eyes with mild to moderate keratoconus.

Setting:

Sankara eye center, Coimbatore , India

Methods:

In prospective case series 28 eyes of 22 patients with keratoconus were included. Inclusion criterion were keratoconus with corneal thickness of more than 400 µm at thinnest point and age older than 18 yrs. Cases with corneal scarring or vogt striae on slit lamp examination, advanced keratoconus cases in whom wavefront map was not obtained and in whom post PRK expected residual bed thickness was less than 350 µm were excluded. All patients underwent wavefront guided PRK. Topographic map and wavefront data were obtained. Customization was performed based on manifest refraction, wavefront refraction and higher order aberrations. Adjusting attempted correction and ablation zone could lower the maximum depth of tissue removed. Size of optic zone ranged from 4 to 6 mm depending on the location of cone on topographic map. PRK was immediately followed by accelerated C3R. Riboflavin drops were applied at one minute intervals for a total induction period of 8-10 minutes followed by UVA irradiation with a power of 30 mW/cm2 and duration of 3 to 3.4 minutes to deliver total energy of 5.4 to 6.6 J/cm2. Post operatively dexamethasone eye drops were used in tapering dosage for 3weeks.

Results:

Mean follow up was 9 months ( range 4 to 14 months). Results were evaluated in terms of visual, refractive , topographic and higher order aberrations outcome. Visual outcome was measured in change in uncorrected distance visual acuity (UCVA) and best corrected distance visual acuity (BCVA). UCVA improved significantly from preoperative mean value of 0.887 Logmar units to 0.262 Logmar units (p value < 0.05 ). BCVA improved from preoperative mean value of 0.188 to 0.087 Logmar units. Postoperatively at last follow up, all eyes had BCVA of 20/60 (Snellen) or better. No eye lost any lines of BCVA whereas 12 out of 28 eyes (43%) gained one or more lines postoperatively whereas 21 out of 28 eyes ( 75% ) gained 3 or more lines of UCVA . Refractive outcome was change in manifest spherical equivalent refraction. Mean spherical equivalent refraction improved significantly from -3.23D t0 -0.62D ( p value < 0.05 ). Topographic outcome was flattening of simulated keratometry values. The mean steepest keratometry was reduced significantly from 47.94D preoperatively to 44.28 D at last follow up( p value <0.05). Corneal higher order aberrations (HOA) were significantly reduced.

Conclusions:

Results in this study shows that simultaneous wavefront guided PRK with accelerated C3R can halt the progression of keratoconus and provide better refractive, topographic and HOA results by reshaping the cornea and flattening and regularizing the anterior corneal surface. To best of our knowledge results of simultaneous wavefront guided PRK with accelerated C3R are not available and this technique can be considered in cases with mild to moderate keratoconus as this approach has the potential to enhance visual rehabilitation in eyes with keratoconus. FINANCIAL INTEREST: NONE