Corneal Densitometry and Higher Order Aberrations After Bowman Layer Transplantation: 1-Year Results

To evaluate corneal densitometry and higher order aberrations (HOAs) up to 1 year after Bowman layer (BL) transplantation.

This was a retrospective study carried out at a tertiary referral center. Fifteen eyes of 14 patients who underwent BL transplantation for advanced keratoconus and had at least 1 year of follow-up were examined before BL transplantation and postoperatively at 1 day, 1 week, and 1, 3, 6, and 12 months. Corrected distance visual acuity (CDVA) with spectacles and contact lenses, anterior and posterior HOAs, and corneal densitometry were analyzed.

One year after surgery, average logarithm of the minimum angle of resolution of spectacle-CDVA changed from 1.35 (±0.46) preoperatively to 0.96 (±0.32, P < 0.001), whereas average logarithm of the minimum angle of resolution of CDVA with contact lens remained stable after surgery (P = 0.126). Anterior and posterior HOA root mean square decreased from 3.08 ± 0.59 to 2.67 ± 0.71 μm and 7.32 ± 2.20 to 6.30 ± 2.18 μm, respectively (P < 0.05). Spherical aberration ((Equation is included in full-text article.)) improved on both anterior and posterior corneal surfaces (P < 0.001). After 1 year, corneal backscattering values showed an increase as compared with preoperative values mostly involving the central and posterior layers of the cornea, with a peak 1 month after surgery (P < 0.005 in zones 2-6 and 6-10 mm). No correlation between HOAs or corneal backscatter and CDVA was found.

Corneal HOAs, especially spherical aberration, decreased for both anterior and posterior corneal surfaces after BL transplantation, whereas corneal backscattering increased, mostly in the central and posterior layers, where the graft has been placed. Changes in HOAs and corneal backscattering did not correlate with CDVA.