Big-bubble Technique Research Articles

Residual corneal stroma in big-bubble deep anterior lamellar keratoplasty: a histological study in eye-bank corneas

AimTo determine if residual corneal stroma remains on the recipient posterior lamella in big-bubble deep anterior lamellar keratoplasty (DALK).MethodsPneumodissection using the big-bubble technique was carried out on eye-bank corneas mounted...

Comparing deep anterior lamellar keratoplasty and automated lamellar therapeutic keratoplasty in patients with keratoconus

We compared outcomes of deep anterior lamellar keratoplasty (DALK) and automated lamellar therapeutic keratoplasty (ALTK) in patients with keratoconus. Seventy eyes with keratoconus that underwent corneal transplantation using either DALK (n = 40) or ALTK (n = 30) were included in this retrospective study. DALK was performed with Anwar's big-bubble technique and ALTK using an ALTK system. Best-corrected visual acuity (BCVA), refractive results, and complications were analyzed. Mean follow-up in the DALK (16.68 ± 3.36 months) and ALTK (15.27 ± 2.50 months) groups were similar (p = 0.058). Mean final BCVA of patients in the DALK group was 0.31 ± 0.14 logarithm of the minimum angle of resolution (logMAR) and in the ALTK group 0.34 ± 0.15 logMAR, (p = 0.492). Corresponding figures for final postoperative spherical equivalents were -3.45 ± 0.77 D and -4.19 ± 0.99 D, respectively (p = 0.001). Final postoperative degree of astigmatism was similar in the two groups: DALK -4.28 ± 0.66 D; ALTK -4.50 ± 1.05 D (p = 0.307). Final visual acuity outcomes were comparable for the DALK and ALTK groups. Thus, ALTK seem to be as efficacious as DALK for surgical treatment of keratoconus.

Deep Anterior Lamellar Keratoplasty Using Big-Bubble Technique for Treatment of Corneal Stromal Scars

To report the clinical outcomes of deep anterior lamellar keratoplasty (DALK) in patients with anterior corneal stromal scars associated with various etiologies. A total of 79 eyes of 79 patients with corneal stromal scars sparing the Descemet membrane and the endothelium underwent DALK by using big-bubble technique. The main outcome measures of the study were the ability to successfully complete DALK, intraoperative and postoperative complications, best spectacle-corrected visual acuity, refraction, and graft clarity. Seventy-two of the surgical procedures were carried out as DALK, and the mean follow-up time was 28.1 ± 17.9 months (range, 12-78 months). The most frequent indication for DALK surgery was postherpetic keratitis (44%). Complete Descemet membrane exposure via big bubble (descemetic DALK) could be achieved in 57 cases (79%). Fifteen eyes (21%) required layer-by-layer manual dissection (predescemetic DALK). Best spectacle-corrected visual acuity of 6/12 or better was present in 59 eyes (82%) postoperatively. The mean spherical equivalent and topographic astigmatism were -3.32 ± 2.13 (range, -9.13 to +4.75) and -2.97 ± 1.94 (range, -8.0 to +4.50) diopter, respectively. There were 2 instances of stromal graft rejection, which responded to medical therapy. DALK big-bubble technique may be a valuable and safe treatment in patients with corneal stromal scar with healthy endothelium. The visual and refractive outcomes are comparable to standard penetrating keratoplasty, avoiding the risk of endothelial rejection.

Influence of Graft–Host Interface on the Quality of Vision After Deep Anterior Lamellar Keratoplasty in Patients With Keratoconus

To investigate the influence of graft–host interface on the quality of vision after deep anterior lamellar keratoplasty (DALK). Retrospective, nonrandomized, comparative case series. Sixty patients (60 eyes) with advanced keratoconus underwent DALK using the big-bubble technique. Twenty-eight patients had complete stromal excision with Descemet membrane (DM) exposure[DALK with DM baring (DM-DALK)], whereas in 32 cases, a layer of stroma was left adherent to the recipient DM [DALK without DM baring (pre-DM-DALK)]. Twenty-two patients with keratoconus (22 eyes) who underwent penetrating keratoplasty (PK) were chosen for comparison. Main outcome measures were uncorrected visual acuity, best spectacle-corrected visual acuity, low-contrast visual acuity(LCVA), and Pelli-Robson contrast sensitivity. Uncorrected visual acuity was equal in the 3 groups. Median best spectacle–corrected visual acuity was 0.1 logarithm of the minimum angle of resolution (logMAR) in the PK group, compared with 0.06 logMAR in the DM-DALK group (P = 0.66) and 0.12 logMAR in the pre-DM-DALK group (P = 0.016). Pre-DM-DALK patients exhibited worse LCVA than PK (P = 0.029) and DM-DALK patients (P = 0.022), whereas PK and DM-DALK patients showed comparable LCVA (P = 0.974). Pelli-Robson contrast sensitivity was equivalent in PK and DM-DALK groups (P = 0.408) and greater in DM-DALK group than in pre-DM-DALK group (P = 0.038). In selected patients, quality of vision after DALK was comparable to that after PK when stromal excision was extended to the DM and inferior to vision after PK when layers of stroma were left adherent to the DM. Advances in DALK technique are required to allow easier and repeatable baring of the DM.

Acute Hydrops After Deep Anterior Lamellar Keratoplasty in a Patient With Keratoconus

To report the occurrence of acute hydrops 52 months after successful deep anterior lamellar keratoplasty (DALK) using the Anwar big-bubble technique in a keratoconic eye. A 20-year-old man with a history of bilateral keratoconus who had undergone DALK in his right eye, presented with complaints of sudden visual reduction, photophobia, redness, and pain in the same eye. Review of his clinical course, slit-lamp biomicroscopy, and laboratory evaluation, including ultrasound biomicroscopy, revealed acute hydrops in the graft. He was medicated with hypertonic solutions but because of persistent graft edema and nonattached Descemet membrane, penetrating keratoplasty was performed. Histopathologic examination confirmed the diagnosis. Similar to penetrating keratoplasty, acute hydrops can occur after DALK using the big-bubble technique in patients with keratoconus.

Graft Biomechanical Properties after Penetrating Keratoplasty versus Deep Anterior Lamellar Keratoplasty

Purpose: To compare biomechanical properties of transplanted corneas after penetrating keratoplasty (PK) with those after deep anterior lamellar keratoplasty (DALK) using Anwar’s big-bubble technique.Materials and Methods: This cross-sectional comparative study consisted of 45 PK eyes (group 1) and 23 DALK eyes (group 2) with the underlying pathology of keratoconus. The Ocular Response Analyzer was used to measure Goldmann-correlated intraocular pressure (IOPg) and cornea-compensated IOP (IOPcc), as well as graft biomechanical properties, namely corneal hysteresis (CH) and corneal resistance factor (CRF). The results were compared between the study groups using independent t-test.Results: Mean patient age was 29.8 ± 6.1 years in group 1 and 27.2 ± 6.5 years in group 2 (P = 0.11) and they were followed up for 31.4 ± 19.0 months and 29.2 ± 17.3 months after corneal transplantation, respectively (P = 0.27). There was no significant difference between the study groups in terms of recipient (P = 0.21) and donor (P = 0.57) trephine sizes or BSCVA (P = 0.77). CH was measured 10.09 ± 2.5 mmHg in group 1 and 9.64 ± 2.1 mmHg in group 2 (P = 0.36). CRF was 10.13 ± 2.2 and 9.36 ± 2.1 mmHg, respectively (P = 0.17). Similarly, no significant difference was found between group 1 and group 2 in terms of IOPg (P = 0.25) and IOPcc (P = 0.80).Conclusion: DALK using the big-bubble technique for keratoconic eyes provides corneal biomechanics comparable to PK.

Deep Lamellar Keratoplasty After Resolution of Hydrops in Keratoconus

Deep anterior lamellar keratoplasty (DALK) using Anwar's big-bubble technique is contraindicated in cases of previous hydrops because of the risk of Descemet membrane (DM) rupture at the hydrops scar. Improved manual lamellar dissection techniques down to the deepest stromal layers now enable manual DALK surgery for previous hydrops with the possibility of obtaining good vision, as an alternative to conventional penetrating keratoplasty. Two retrospective case reports of manual DALK in patients with previous hydrops. A 12-year-old boy, with keratoconus and resolved hydrops in his left eye with deep stromal scarring, underwent bilateral manual DALK without baring of the DM. An intraoperative microperforation occurred in his left eye and was managed by intracameral injection of air to seal the perforation. Eleven months after his right DALK and 10 months after his left DALK, his right best spectacle-corrected visual acuity (BSCVA) was 20/20, and his left BSCVA was 20/25. The right cornea was clear, whereas the left cornea had minimal residual deep stromal scarring. Endothelial cell count by specular microscopy was 2611 cells per square millimeter in the right eye and 2193 cells per square millimeter in the left eye. A 28-year-old man, with keratoconus and resolved hydrops in his right eye with deep stromal scarring, underwent right manual DALK without baring of the DM. Nine months postoperatively, his right BSCVA was 20/30, and the graft was clear. Endothelial cell count by specular microscopy was 3148 cells per square millimeter in the right eye. DALK can be performed in patients with previous hydrops. A controlled deep manual dissection technique without baring the DM is advocated. Good final BSCVA can be achieved despite leaving a thin residual layer of the stroma unexcised.

Effect of Vitreous Length and Trephine Size Disparity on Post-DALK Refractive Status

To evaluate the effect of vitreous length (distance between posterior lens surface and vitreoretinal interface) and donor-recipient disparity on the refraction and keratometric astigmatism after deep anterior lamellar keratoplasty (DALK). In this retrospective comparative study, 85 eyes of 83 patients with keratoconus underwent DALK using the big-bubble technique. A 0.25-mm oversize donor was used for a vitreous length of ≥ 16.0 mm, and a 0.50-mm oversize donor for a vitreous length of <16.0 mm. At least 3 months after complete suture removal, spherical equivalent refractive error (SE), keratometric astigmatism, and mean keratometry were compared between the 2 groups. Multiple regression analysis was performed in group 1 to investigate the correlation between vitreous length and SE, between vitreous length and keratometric astigmatism, and between mean keratometry and SE. Mean patient age was 26.5 ± 7.7 years, and they were followed for 22 ± 10 months postoperatively. Seventy-five eyes received a 0.25-mm oversize donor (group 1), and 10 had a donor oversized by 0.50 mm (group 2). Compared with group 1, the patients of group 2 had a significantly steeper cornea (46.83 ± 2.0 vs. 48.29 ± 1.9 diopters, respectively; P = 0.01). SE and keratometric astigmatism in group 1 did not significantly differ from those in group 2. In group 1, there was a significant association between vitreous length and SE and between mean keratometry and SE but not between vitreous length and keratometric astigmatism. In DALK, a donor oversized by 0.25 mm is advisable for elongated keratoconic eyes, whereas a 0.50-mm oversize donor is advocated for small ones.

Long-Term Results of Deep Anterior Lamellar Keratoplasty for the Treatment of Keratoconus

To evaluate the long-term endothelial cell density (ECD) changes and visual and refractive outcomes after deep anterior lamellar keratoplasty (DALK) using the big-bubble technique in eyes with keratoconus. Retrospective interventional case series study. setting: Single hospital. patients: Two hundred forty-one eyes of 214 patients who underwent DALK for moderate to advanced keratoconus. main outcome measures: Intraoperative and postoperative complications, postoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), spherical equivalent refraction, topographic astigmatism, and ECD. Two hundred thirty-four procedures (97%) were completed as DALK. Big bubble was successfully achieved in 193 eyes (82.4%). In 7 eyes (3%), the procedure was converted to penetrating keratoplasty because of Descemet membrane macroperforations. Microperforations occurred in 18 eyes (7.5%). The mean follow-up time was 50.5 ± 22.2 months (range 24 to 96 months). UCVA was lower than 20/100 in all eyes preoperatively and better than 20/100 in 191 eyes (81.6%) postoperatively. BSCVA was 20/40 or better in 187 eyes (79.9%) and 20/20 or better in 38 eyes (16.2%). The mean (± SD) preoperative ECD that was possible in 166 eyes was 2797 ± 561 cells/mm(2). Mean (± SD) endothelial cell loss was 8.1% ± 4.6% at 1 year, 10.5% ± 5.7% at 2 years, 15.1% ± 14.8% at 6 years, and 22.5% ± 15.9% at 8 years. Stromal graft rejection episodes occurred in 4 eyes, which resolved with appropriate therapy. Deep anterior lamellar keratoplasty that uses the big-bubble technique is effective in patients with keratoconus. Long-term endothelial cell loss was moderate and lower than penetrating keratoplasty grafts.

Femtosecond-Assisted Deep Anterior Lamellar Keratoplasty Using Big-Bubble Technique in a Cornea With 16 Radial Keratotomy Incisions

To report on a patient with uncorrectable fluctuating astigmatism from multiple previous radial keratotomy (RK) procedures who successfully underwent a femtosecond laser-assisted deep anterior lamellar keratoplasty (DALK) with big-bubble technique. A 60-year-old woman with a history of multiple RK procedures with 16 radial incisions and 4 Ruiz-style cuts had fluctuating corneal astigmatism with preoperative best contact lens-corrected visual acuity of 20/80. Intraoperatively, a femtosecond laser-assisted zigzag pattern DALK was performed. Descemet baring was successfully achieved using the big-bubble technique without air escaping from the radial incisions, likely related to precise depth of base of posterior side cut made by laser. Postoperative best-corrected visual acuity is 20/25 with 1.3 diopter of astigmatism at 5 months. To our knowledge, this is the first report to use this technique in a cornea with RK incisions. Femtosecond lasers may promote the success of DALK in challenging corneas.

Common complications of deep lamellar keratoplasty in the early phase of the learning curve

Purpose:To evaluate and record the common complications that face surgeons when they perform their first few series of deep lamellar keratoplasty and measures to avoid these.Setting:Dar El Oyoun Hospital, Cairo, Egypt.Methods:Retrospective study of the first 40 eyes of 40 patients carried out by two corneal surgeons working in the same center. All patients were planned to undergo a deep anterior lamellar keratoplasty using the big bubble technique. Twelve patients suffered from keratoconus while 28 patients had anterior corneal pathologies. Recorded complications were classified as either intraoperative or postoperative.Results:Perforation of Descemet’s membrane was the most common intraoperative complication. It occurred in nine eyes (22.5%): five eyes (12.5%) had microperforations while four eyes (10%) had macroperforations, three eyes (7.5%) had central perforations, and six eyes (15%) had peripheral perforations. Other complications included incomplete separation of Descemet’s membrane and remnants of peripheral stromal tissue. Postoperative complications included double anterior chamber which occurred in four eyes (10%) and Descemet’s membrane corrugations. Postoperative astigmatism ranged from 1.25 to 4.5 diopters with a mean of 2.86 diopters in the whole series, but in the six cases with identified residual stroma in the periphery of the host bed, the astigmatism ranged from 2.75 to 4.5 diopters with a mean of 3.62 diopters.Conclusion:Deep lamellar keratoplasty is sensitive to procedural details. Learning the common complications and how to avoid them helps novice surgeons to learn the procedure faster.

Deep Anterior Lamellar Keratoplasty for Maroteaux-Lamy Syndrome

To present a case of Maroteaux-Lamy syndrome (MLS), which underwent deep anterior lamellar keratoplasty (DALK) for visual rehabilitation. A 15-year-old girl with MLS was admitted with severe corneal opacity. We performed DALK on her left eye for visual rehabilitation. Big-bubble technique was used to perform lamellar separation. Corneal graft was clear 24 months after surgery. Best spectacle-corrected visual acuity of left eye was 20/25 with the correction of +0.75/-0.50 diopters × 170. At the last follow-up, in vivo confocal microscopy revealed mild haze in the posterior stroma at the graft interface level. Endothelial cell count was 2473.4 cells per square millimeter using a noncontact specular microscope. Given systemic problems in patients with MLS and less postoperative complications of DALK in comparison with penetrating keratoplasty, it seems DALK is the better choice for these patients.

Visual Acuity and Refraction After Deep Anterior Lamellar Keratoplasty With and Without Successful Big-Bubble Formation

To compare visual acuity and refractive outcomes after Anwar's deep anterior lamellar keratoplasty (DALK) between eyes with and without successful big-bubble formation. In this retrospective comparative study, keratoconic eyes undergoing DALK with the big-bubble technique were divided into 2 groups: group 1 in which a bared Descemet membrane (DM) was achieved and group 2 in which layer-by-layer manual dissection was performed because of the lack of big-bubble formation after several intrastromal air injections. The 2 groups were compared with respect to best spectacle-corrected visual acuity, keratometric astigmatism, and refractive error at months 1, 3, 6, and 12, and at least 3 months after complete suture removal. A total of 123 keratoconic eyes were enrolled. A bared DM was successfully achieved in 100 eyes (81.3%) (group 1), whereas in 23 eyes (18.7%) (group 2), some posterior stroma was left in place. The mean follow-up period was 21 ± 9 months in group 1 and 23 ± 9 months in group 2 (P = 0.37). Postoperative best spectacle-corrected visual acuity was significantly better in group 1 than in group 2 at months 1, 3, 6, and 12. But, at the final examinations, there was no significant difference between the study groups (0.24 ± 0.21 logarithm of the minimum angle of resolution in group 1 and 0.32 ± 0.14 logarithm of the minimum angle of resolution in group 2; P = 0.18). The 2 groups were comparable regarding keratometric astigmatism and spherical equivalent refractive error throughout the follow-up period. Retention of posterior corneal stroma delayed visual recovery after DALK using Anwar's technique, but the participants in this group ultimately reached the same levels of visual acuity as observed in the bared-DM group.

Conversion to Deep Anterior Lamellar Keratoplasty (DALK): Learning Curve with Big-Bubble Technique

To report the perioperative complications and clinical outcomes of 50 deep anterior lamellar keratoplasty (DALK) cases. Fifty eyes of 50 patients with pathologies involving the corneal stroma and sparing the Descemet's membrane and endothelium were included consecutively in this prospective, noncomparative interventional case series study. DALK was performed using the big-bubble technique. The most frequent indication for DALK surgery was keratoconus (26 eyes), followed by corneal dystrophy (10 eyes) and superficial corneal scar (14 eyes). The average follow-up period was 12.0 ± 3.9 months. DALK was completed in 41 cases (82%). A big bubble was achieved successfully in 37 cases (74%). Descemet's membrane perforations occurred in 14 (28%) eyes, 8 of which were macroperforation and necessitated conversion to penetrating keratoplasty. Complications tended to decrease throughout the study. Postoperative best-corrected visual acuity of 0.5 or better was present in 30 of 41 (73.2%) eyes that underwent DALK. There was no episode of graft rejection. DALK big-bubble technique may be a valuable procedure during transition from penetrating keratoplasty to anterior lamellar keratoplasty. It provided acceptable visual and refractive outcome even during the learning period in a variety of corneal lesions.

Standardized big-bubble technique in deep anterior lamellar keratoplasty assisted by the femtosecond laser

We describe a variant of the big-bubble technique in deep anterior lamellar keratoplasty (DALK) assisted by the IntraLase femtosecond laser, which we call IntraBubble. The use of the 60 kHz IntraLase femtosecond laser allows dissection of the pre-Descemet-plane lamella to a predefined corneal depth and creation of a channel in the posterior stroma 50 μm above the endothelium into which a smooth cannula for air injection can be introduced. We lengthened the channel created by the laser using a pointed dissector. Eleven consecutive patients with keratoconus were treated, and all procedures were completed as DALK. The big bubble was achieved in 8 eyes (73%). In 3 cases (27%), intraoperative microperforations occurred and the procedures were completed with hand dissection without complications. This new application of femtosecond laser technology could lead to standardization of the big-bubble technique in DALK.

Endothelial Cell Loss and Visual Outcome of Deep Anterior Lamellar Keratoplasty versus Penetrating Keratoplasty: A Randomized Multicenter Clinical Trial

To compare endothelial cell (EC) loss, visual and refractive outcomes, and complications after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK). Randomized, multicenter clinical trial. Fifty-six eyes of 56 patients with a corneal stromal pathology not affecting the endothelium were randomized to DALK or PK. The DALK procedure was performed according to Anwar's big-bubble technique. Patients underwent an ophthalmic examination preoperatively and 3, 6, and 12 months postoperatively. Endothelial cell loss, refractive and topographic astigmatism, spherical equivalent, uncorrected visual acuity, and best spectacle-corrected visual acuity (BSCVA) were measured, and complications were recorded. Endothelial cell loss was significantly higher after PK compared with DALK procedures performed without perforation of Descemet's membrane (12 months: 27.7% ± 11.1% vs. 12.9% ± 17.6%). The BSCVA was significantly better in the PK group at 3 and 6 months after surgery but was not significantly different 12 months after surgery (0.39 ± 0.3 logarithm of the minimum angle of resolution [logMAR] in DALK and 0.31 ± 0.3 logMAR in PK). At 12 months postoperatively, refractive and topographic astigmatism in the DALK and PK groups were -3.37 ± 2.3 diopters (D) and -3.76 ± 2.1 D (P = 0.53), and 3.57 ± 2.3 D and 4.16 ± 2.0 D (P = 0.34), respectively. (Micro)perforation of the Descemet's membrane occurred in 32% (9/28) of the DALK eyes, and 18% (5/28) of the patients required conversion to PK. Endothelial cell loss was not significantly different between DALK and PK when cases with perforation of Descemet's membrane were included in the (intention-to-treat) analysis (12 months: 19.1 ± 21.6 vs. 27.7 ± 11.1 P = 0.112). Rejection episodes were reported in 1 patient in the DALK group (epithelial rejection) and 3 patients in the PK group (all endothelial rejections). No graft failure occurred. One year after DALK performed without perforation of Descemet's membrane, EC loss is significantly lower, whereas the BSCVA is comparable to that in the PK group. In addition, no endothelial rejection occurred in the DALK group. However, Descemet's membrane perforation remains a major complication in DALK and warrants improvements to standardize the big-bubble technique.

Visual acuity outcomes after deep anterior lamellar keratoplasty: a case-control study

AimTo compare visual outcomes between deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK). Secondarily to compare refractive outcomes, complications and graft survival between the three cohorts.MethodsRetrospective case-control study evaluating...

Pre‐cut posterior corneal lamellae with a stromal rim used for Descemet’s membrane endothelial keratoplasty with a stromal rim (DMEK‐S)

Abstract Purpose To standardize a technique for the manual preparation of posterior corneal lamellae for DMEK‐S under the conditions of an ocular tissue bank. To assess the qualitative and quantitative parameters of the lamellar endothelium with the aim of establishing the parameters of corneas intended for preparation. Methods Corneoscleral buttons 17mm in diameter not suitable for grafting were used. Group 1 contained 12 corneas with a live endothelial cell density ≥ 2500 cells/mm2. Group 2 contained 10 corneas with a density lower than 2500 cells/mm2. The lamellae, consisting of a central 6mm zone of endothelium‐Descemet’s membrane surrounded by a supporting peripheral stromal rim, were prepared manually using the big bubble technique. The percentage of dead cells and the live endothelial cell density were assessed before and immediately after preparation as well as after 48 hours of organ culture storage using light microscopy following 0.15% trypan blue and 0.9% sucrose treatment. Results Immediately after the preparation, on average 4.9 % and 5.2 % of dead cells were found in group 1 and group 2, respectively. The percentage of dead cells decreased significantly during subsequent storage in organ culture in both groups (to 1.5 % and 1.7 % for group 1 and 2). There was no significant decrease in live endothelial cell density in group 1 during 48 hours of culturing; however, there was a significant decrease in group 2. Conclusion The decrease in endothelial cell density during organ culturing depends on the original values. We suggest that the minimal acceptable live endothelial cell density of corneas intended for preparation should be 2500 cells/mm2 to ensure the best clinical outcomes.

Deep anterior lamellar keratoplasty using the big-bubble technique for keratectasia after laser in situ keratomileusis

To evaluate the efficacy of deep anterior lamellar keratoplasty (DALK) using the big-bubble technique to manage keratectasia after laser in situ keratomileusis (LASIK). Ophthalmology Department and Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. In this interventional case series, preoperative and postoperative data of patients who had post-LASIK ectasia and DALK using the Anwar big-bubble technique between April 2005 and May 2008 were compiled. Indications for keratoplasty were intolerance of rigid gas-permeable contact lenses or unacceptable corrected visual acuity. Preoperative and postoperative uncorrected (UDVA) and corrected (CDVA) distance visual acuities, spherical equivalent (SE) refractive error, mean keratometry, and keratometric astigmatism were compared. The study included 11 eyes of 10 patients (mean age 31.6 years +/- 7.4 [SD]). The mean follow-up was 20.2 +/- 6.5 months. The mean UDVA increased from 20/400 before DALK to 20/160 after DALK (P = .39) and the CDVA, from 20/160 to 20/40, respectively (P = .007). The increase in the mean SE refractive error was 1.94 diopters (D) (from -11.53 +/- 5.4 D to -13.47 +/- 10.5 D) (P = .34). The mean keratometry was 46.81 +/- 7.2 D preoperatively and 46.31 +/- 1.9 D postoperatively (P = .81) and the mean keratometric astigmatism, 4.75 +/- 2.6 D and 4.55 +/- 2.5 D, respectively (P = .81), showing little change in either parameter. Deep anterior lamellar keratoplasty using the big-bubble technique effectively restored corneal regularity and thus increased CDVA; however, a high refractive error should be expected postoperatively. Neither author has a financial or proprietary interest in any material or method mentioned.

Refractive Outcome of Keratoconus Treated by Combined Femtosecond Laser and Big-Bubble Deep Anterior Lamellar Keratoplasty

To report 1-year follow-up in 11 of 13 eyes with keratoconus treated by deep anterior lamellar keratoplasty with a combined femtosecond laser lamellar resection followed by a big-bubble dissection. Thirteen eyes with keratoconus were treated. Recipient and donor were prepared with the 60-kHz IntraLase femtosecond laser (Abbott Medical Optics). In the recipient, the femtosecond laser, after performing a lamellar cut 100 μm above the thinnest corneal point (measured by Pentacam [Oculus Optikgeräte GmbH]), was used to make a mushroom-shaped resection (anterior diameter, 9 mm; posterior diameter, 8 mm) from the same depth. In the donor, the mushroom lamellar thickness was calculated according to an original model based on the recipient preoperative corneal thickness. Upon removal of the recipient lamella, air was injected into the residual stroma to achieve a big bubble. The keratectomy was continued up to Descemet membrane. The donor was fit into place and sutured using interrupted sutures, which were removed by 8 months postoperative. Corrected distance visual acuity (CDVA) and refractive astigmatism were calculated by manifest refraction, whereas topographic astigmatism and corneal thickness were measured by Pentacam. A big bubble was successfully achieved in 11 eyes. Twelve months after surgery, mean CDVA was 0.52±1.2 (decimal), and refractive sphere and cylinder were -1.50±1.70 diopters (D) and 2.00±2.60 D, respectively. Three (27%) of 11 eyes at 1 year had a manifest refraction spherical equivalent within 1.00 D of emmetropia. Topographic astigmatism was 2.90±1.60 D. The thinnest corneal point was 519±27 μm. This combination of a femtosecond laser lamellar dissection with a big-bubble technique can improve the standardization of deep anterior lamellar keratoplasty for keratoconus.