Fourier-domain optical coherence tomography-guided phototherapeutic keratectomy for the treatment of anterior corneal scarring

AIM:To evaluate the safety,visual and anatomic outcomes of fourier-domain optical coherence tomography(FD-OCT)-guided excimer laser phototherapeutic keratectomy(PTK)combined with photorefractive keratectomy(PRK)surgery in treating anterior corneal scarring.METHODS:Clinical data of 23 eyes of 21 patients with anterior corneal scarring underwent FD-OCT-guided PTK and PRK from Dec.2014 to Jul.2016 were reviewed.Patients were assessed for preoperative and postoperative uncorrected visual acuity(UCVA),best spectacle-corrected visual acuity(BSCVA),contrast sensitivity(CS),FD-OCT,corneal topography and colour figures of anterior segments.RESULTS:The preoperative corneal pathologic conditions included viral keratitis(7 patients,7 eyes),band keratopathy(2 patients,4 eyes),corneal dystrophy(4 patients,4 eyes),traumatic corneal disease(2 patients,2 eyes)and corneal chemical injury(6 patients,6 eyes).Mean follow-up time was 10.65(range,3-19)mo.UCVA(in IogMAR)improved from a mean of 0.79(95%Cl,0.28­1.29)preoperatively to a mean of 0.45(95%Cl,0.29-0.62)postoperatively(P=0.021).BSCVA(in IogMAR)improved from 0.57(95%Cl,0.27-0.88)preoperatively to a mean of 0.28(95%Cl,0.15-0.41)postoperatively(P=0.001).Corneal topographic indices postoperatively showed significant improvement in corneal cylinder(P=0.009),the surface regularity index(P=0.007)and surface asymmetry index(P=0.00).Postoperative spherical equivalent averaged-0.53 diopters(-1.49 to 0.42).No complications were associated with the treatment.CONCLUSION:FD-OCT-guided PTK combined with PRK is safe and effective for the treatment of anterior corneal scarring by eliminating or reducing corneal opacities.

Femtosecond laser-assisted deep anterior lamellar keratoplasty in phototherapeutic keratectomy versus the big-bubble technique in keratoconus

AIM:To compare the functional and anatomic results of femtosecond laser(FSL)-assisted deep anterior lamellar keratoplasty(DALK) associated with phototherapeutic keratectomy(PTK) and FSL-assisted DALK performed using the big-bubble technique in keratoconus.METHODS:During the first phase of the study,an electron microscopy histopathology pilot study was conducted that included four unsuitable donor corneas divided into two groups:in FSL group,FSL lamellar cuts were performed on two corneas and in FSL+PTK group,PTK was performed at the stromal beds of two corneas after FSL lamellar cuts were made.During the second phase of the study,a randomized clinical trial was conducted that included two treatment groups of patients with keratoconus:group 1(n=14 eyes) underwent FSL-assisted DALK associated with PTK and group 2(n=12 eyes) underwent FSL-assisted DALK associated with the bigbubble technique.The main outcome measures were the postoperative visual acuity(VA) and optical coherence tomography(OCT) measurements,confocal microscopic findings,and contrast sensitivity.RESULTS:In the pilot study,histopathology showed a more regular stromal bed in the FSL+PTK group.In the clinical trial,group 1 had significantly worse best spectaclecorrected VA and contrast sensitivity(P<0.05 for both comparisons).The residual stromal bed measured by OCT was significantly(P<0.05) thicker in group 1.Confocal microscopy detected opacities only at the donor-receptor interface in group 1.CONCLUSION:Patients with keratoconus treated with FSL-assisted DALK performed using the big-bubble technique fare better than treated with FSL-assisted DALK associated with PTK.

Treatment of anterior corneal scarring,following DSAEK graft failure,with combined graft exchange and phototherapeutic keratectomy

Background:To present a method,alternative to penetrating keratoplasty,for the restoration of impaired corneal clarity with anterior stromal scarring following long-standing corneal graft failure.Case presentation:A 48-year old female who had previously underwent Descemet stripping automated endothelial keratoplasty(DSAEK)for the treatment of pseudophakic bullous keratopathy,presented with longstanding corneal oedema and anterior corneal scarring.A significant improvement in corrected distance visual acuity was demonstrated,as corneal clarity was restored following graft exchange and phototherapeutic keratectomy(PTK).Conclusions:The combination of corneal graft exchange and phototherapeutic keratectomy may represent an effective therapeutic option for long-standing corneal oedema with concomitant anterior corneal scarring after failure of a DSAEK graft.