Both penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) offer significant visual and refractive improvements to patients with advanced keratoconus. However, the outcomes are not always equivalent, and each procedure has its potential complications.
Study design
This was a retrospective study of 411 eyes (378 patients) with keratoconus that were treated with either PK or DALK. All eyes had a preoperative mean keratometry measurement of ≥60 D. Outcome measures for comparison included postoperative vision, refraction, and complications.
Outcomes
Visual acuity and refraction improved in both groups, but postoperative corrected distance visual acuity was significantly better among eyes in the PK group compared to those in the DALK group (0.18 vs 0.26 logMAR, respectively). Furthermore, the mean spherical equivalent was less myopic in the PK group. Both groups showed similar reductions in astigmatism. Whereas suture complications were more commonly observed in DALK eyes than PK eyes (72% vs 48.6%, respectively), graft rejection occurred more frequently after PK than after DALK (33.5% vs 19.7%).
Limitations
Limitations of this study include its retrospective approach, lack of endothelial cell density data, and absence of visual quality metrics, including contrast sensitivity. The definition of advanced keratoconus used in the study also differs from definitions used by other studies, so these results may not be broadly comparable.
Clinical significance
While traditional teaching favors the use of DALK over PK in eyes with keratoconus, this article highlights how each has its pros and cons. Based on these findings, cornea surgeons are encouraged to counsel patients on differences in outcomes that could be expected with the two procedures prior to undergoing keratoplasty.
Financial disclosures: Dr. Zeba Syed discloses financial relationships with Bio-Tissue (Lecture Fees/Speakers Bureau); Dompe (Grant Support); Glaukos Corporation (Grant Support).