OBJECTIVE: To compare the outcomes and complications of Epi-Bowman blunt keratectomy (EBK) using a blunt epikeratome (Epi-Clear, Orca Surgical, Israel), with alcohol delamination of the corneal epithelium during photorefractive keratectomy (PRK) in contralateral eyes.
METHODS: This prospective, randomized contralateral eye study included 44 eyes of 22 patients undergoing PRK for bilateral myopia or myopic astigmatism. In each patient, epithelial delimitation was performed using an Epi-Clear epikeratome EBK (EBK group) on 1 eye and diluted ethanol (EtOH) on the fellow eye (EtOH group). Postoperative pain, epithelial healing, epithelial profile, and visual outcome were compared between the 2 groups.
RESULTS: The mean postoperative pain scores were 0.37 ± 0.25 for the EBK group and 0.82 ± 0.22 for the EtOH group (P = 0.043). The mean epithelial defect size at day 3 postoperatively was 1.61 ± 1.46 and 2.25 ± 1.69 mm, respectively (P = 0.034). The postoperative 3-month remaining mean spherical equivalent was 0.04 ± 0.49 diopters for the EBK group and 0.21 ± 0.26 D for the EtOH group (P = 0.520). There was no significant difference in UCVA and BCVA between the groups.
CONCLUSIONS: Our data suggest that this novel EBK device and technique may minimize postoperative pain, accelerate re-epithelialization, and offer earlier visual recovery, compared with EtOH when used for myopic PRK.

A morphological and morphometric study of the adult zebrafish ocular surface was performed to provide a comprehensive description of its parts and to evaluate its similarity to the human.
The eyes of adult zebrafish were processed for light, transmission and scanning electron microscopy, and for immunohistochemical stain of corneal nerves; a morphometric analysis was also performed on several morphological parameters.
The corneal epithelium was formed by five layers of cells. No Bowman\'s layer could be demonstrated. The stroma consisted of lamellae of different thickness with few keratocytes. The Descemet\'s membrane was absent as the flat and polygonal endothelial cells directly adhered to the deepest corneal lamella. The immunohistochemical stain of neurofilaments failed to demonstrate corneal nerve fibers. The conjunctival epithelium was stratified, overlying the stroma formed by a subepithelial and a deep layer, this latter connected to the scleral cartilage. In the peripheral cornea and in the conjunctiva, many goblet and rodlet cells were observed. The morphometric analysis showed that the peripheral cornea epithelium was thicker when compared to the other parts of the ocular surface, with smaller superficial cells. Desmosomes and hemidesmosomes in the conjunctiva were significantly fewer in number than the other parts of the ocular surface. The stroma was thinner in the conjunctiva than in the cornea, while corneal lamellae were thicker in the intermediate stroma.
The zebrafish ocular surface showed significant differences compared to the human, such as the absence of Bowman\'s layer, Descemet\'s membrane and corneal nerve fibers, the reduced stromal thickness, and the presence of rodlet cells. On the basis of these original findings, it is suggested that the use of the zebrafish as a model for studying normal or pathological human corneas should be undertaken with particular caution.

To evaluate the technical feasibility of isolated Bowman layer (BL) graft preparation by femtosecond laser (FSL) and to compare the ultrastructural morphology to manually dissected grafts.
Five whole globes were placed in custom-made eye holders and debrided of epithelium. After programming a dissection depth of 20 μm, the FSL was docked into position and 5 isolated BL grafts were created. From 5 additional globes, corneoscleral buttons were procured, mounted in artificial anterior chambers, and stripped of BL via the previously described manual technique. Three specimens from both series were randomly selected and assigned to transmission electron microscopy for ultrastructural evaluation and thickness measurements.
All dissections were uneventful and 10 total grafts were produced: 5 by FSL and 5 by manual dissection. Mean graft thickness was 37 (±8.6) μm (n = 3) for the FSL group and 11.7 (±1.6) μm (n = 3) for the manually dissected group. Transmission electron microscopy revealed a thick but relatively smooth posterior cut edge in the FSL group, versus a virtually isolated BL with irregular rests of dispersed stroma in the manually dissected group.
Femtosecond laser may have potential for harvesting intact BL and with a smooth posterior surface, but accompanied by variable amounts of anterior stroma owing to technical limitations.

The purpose of this study is to compare the efficacy and safety of Epi-Bowman Keratectomy (EBK) using Epi-clear™ epikeratome with a mechanical scraper for corneal epithelium debridement during photorefractive keratectomy (PRK) and corneal collagen cross-linking (CXL).
Sixty eyes of 30 patients undergoing PRK and 44 eyes of 44 patients undergoing CXL were included in this study. In the PRK group, one eye of each patient underwent EBK and the other eye epithelial debridement with a mechanical scraper. In the CXL group, 22 eyes of 22 patients underwent EBK and the other 22 eyes with a mechanical scraping to remove the epithelium. Intra-operative spectral domain optical coherence tomography (SD OCT; Bioptigen Inc, Durham, NC) was performed to evaluate the integrity of Bowman\'s membrane following epithelial removal. The time taken for epithelial removal, post-operative pain score using the Wong-Baker\'s pain scale, time for epithelial healing, and the epithelial profile using the Optovue (Optovue Inc. Fremont, CA) during the healing was observed and analyzed between the two groups and subgroups.
Intra-operative SD OCT showed a smooth and undamaged Bowman\'s membrane when EBK was performed. Post-operative pain was significantly less (p < 0.01 in the PRK group and p < 0.001 in the CXL group) with faster epithelial healing (p < 0.001 in the PRK group and p < 0.0001 in the CXL group) in the EBK subgroup as compared with the mechanical scraper subgroup. Epithelial profiling during the healing phase showed an edematous epithelium in the initial 2 weeks in the mechanical scraper subgroup while the EBK subgroup showed minimal epithelial edema lasting up to a week with regularized and smooth corneal epithelium healing.
Epi-Bowman Keratectomy appears to be an effective and safe method of corneal epithelial debridement with negligible damage to Bowman\'s membrane and the surrounding epithelium leading to early healing thereby reducing the post-operative pain and complications.

OBJECTIVE: To compare the outcomes of sub-Bowman keratomileusis (100-μm flap) and laser in situ keratomileusis (LASIK) (120-μm flap) using 150-kHz femtosecond laser.
METHODS: Randomized, double-masked, contralateral clinical trial.
METHODS: One hundred patients (200 eyes) with myopia or myopic astigmatism were included. Postoperative examinations were performed at week 1 and months 1, 3, 6, and 12. Main outcome measures included postoperative uncorrected (UCVA) and best-corrected distance visual acuity (BCVA); manifest refraction spherical equivalent; efficacy and safety indices; corneal thickness; and complications.
RESULTS: The mean age of patients was 33.9 ± 7.9 years. Overall, the preoperative UCVA, BCVA, and manifest refraction spherical equivalent were 1.349 ± 0.332, -0.022 ± 0.033, and -5.81 ± 1.61 diopters, respectively. No significant difference was observed in preoperative (P ≥ .226) or intraoperative parameters (P ≥ .452) between both groups, except residual stromal thickness (P < .001). The UCVA, manifest refraction spherical equivalent, and central corneal thickness stabilized by 1 week, while the thinnest corneal thickness stabilized by 3 months postoperatively. There was no significant difference between both groups for any parameter during all follow-up visits (P ≥ .132) except the 3-month safety index, which was better in the sub-Bowman keratomileusis group (P = .007). Soft opaque bubble layer was noted intraoperatively in 12 cases (7, 100-μm group; 5, 120-μm group; P = .577). No postoperative complications were observed.
CONCLUSIONS: Our study did not find any differences in the visual and refractive outcomes between femtosecond-assisted sub-Bowman keratomileusis and LASIK. Both surgeries resulted in quick visual recovery as early as 1 week postoperatively.

Our study performed qualitative and quantitative studies on the corneal ultrastructure of healthy female Merino sheep of ages 4 months and 6 years old from the Argentinean Pampa. The corneas were evaluated using ex vivo laser-scanning confocal microscopy, light microscopy and transmission electron microscopy. Those studies allowed us to obtain detailed images of the corneal layers as well as quantitative data of the cellular and sub-basal nerve densities in the cornea from sheep of different ages. The density of the corneal cells was significantly different in the anterior versus the posterior epithelium and stroma. Moreover, the density of the epithelial, stromal cells and endothelial cells, as well as the sub-basal nerve density were significantly lower in adult than in young animals. Our work provided a wide-ranging description of the corneal ultrastructure of healthy female Merino sheep, which adds to the current knowledge about the ophthalmological aspects of this species and undoubtedly benefits veterinarians.

OBJECTIVE: To evaluate the outcome of phototherapeutic keratectomy (PTK) treatment of epithelial basement membrane dystrophy (EBMD) patients and to examine clinical and morphologic signs of recurrent dystrophy.
METHODS: Cross-sectional, clinic-based study.
METHODS: Fifty-two eyes of 39 patients diagnosed with EBMD who underwent PTK between 2001 and 2008.
METHODS: Preoperative symptoms, best spectacle-corrected visual acuity (BSCVA), and refraction data were collected. At follow-up, refraction and BSCVA were measured, symptoms were noted, and slit-lamp biomicroscopy and in vivo confocal microscopy (IVCM) were performed.
METHODS: Best spectacle-corrected visual acuity and signs of recurrent EBMD based on symptoms and morphologic features. An assessment of EBMD severity after PTK additionally was considered.
RESULTS: Mean follow-up time was 43 months (range, 7-100 months). After PTK, BSCVA remained unchanged or improved in 49 (98%) of 51 eyes. Twenty-four (46%) of 52 eyes had recurrence of some form, and recurrence was correlated positively with postoperative time (P<0.001). Symptomatic recurrence occurred in 7 eyes (13%), whereas morphologic recurrence occurred in 21 eyes (40%). Symptoms were coupled with positive IVCM findings in 3 (43%) of 7 cases and with slit-lamp findings in 1 (14%) of 7 cases. Of 17 eyes with morphologic recurrence by IVCM, 9 eyes (53%) were classified as having grade 1 recurrence, 8 eyes (47%) were classified as having grade 2 recurrence, and none were classified as having grade 3 recurrence. Morphologic recurrence was associated with epithelial removal by laser ablation before PTK.
CONCLUSIONS: Although PTK is an effective method of alleviating the clinical symptoms of EBMD, the dystrophy can recur with time. The relationship between the postoperative development of clinical symptoms and the corneal morphologic features is complex and requires further investigation.

OBJECTIVE: To examine the role of Bowman\'s layer (BL) on the nature of anterior corneal regeneration after excimer laser phototherapeutic keratectomy (PTK).
METHODS: A cohort of 13 patients underwent PTK to remove either 7 mum of BL for treatment of primary recurrent corneal erosions (RCE; six patients) or complete BL removal (15-mum ablation) to treat RCE or poor vision secondary to map-dot-fingerprint (MDF) dystrophy (seven patients). Clinical examinations and laser-scanning in vivo confocal microscopy (IVCM) were conducted before surgery and at a mean of 4 and 8 months after surgery.
RESULTS: Total BL removal resulted in a significant decline in subbasal nerve density at 4 months (P = 0.007) that barely recovered to preoperative levels at 8 months (P = 0.055). With BL partially present, subbasal nerve density did not significantly change from preoperative levels. Superficial, wing, and basal epithelial cell density recovered to preoperative levels within 4 months after PTK, regardless of the presence of BL. Subepithelial keratocytes, however, were more densely distributed in corneas without BL relative to those with a partial BL present (P = 0.005), and increased anterior keratocyte reflectivity was noted in all eyes without BL and in no eye with a partial BL present.
CONCLUSIONS: Subbasal nerve regeneration is delayed and subepithelial keratocyte density and reflectivity remain elevated up to 10 months after total BL removal by PTK. The results provide initial evidence for a possible role of BL in facilitating rapid stromal wound healing and an associated recovery of anterior corneal transparency and the restoration of epithelial innervation after epithelial trauma.

To explain the basic science and clinical evidence that has led to the development of a new technique in corneal refractive surgery--sub-Bowman\'s keratomileusis (SBK).
A comprehensive review of the literature and report of a contralateral eye study of 50 patients (100 eyes) enrolled at 2 sites (25 patients per site) and randomized according to the dominant eye was conducted. All eyes underwent a wavefront-guided refractive correction using the Alcon LADARVision4000 System. In one eye, an 8.5-mm, ETOH-assisted photorefractive keratectomy (PRK) was performed. In the second eye, an 8.5-mm, 100-microm flap was attempted using a 60 kHz IntraLase FS femtosecond laser. Pre- and postoperative tests included best spectacle-corrected visual acuity, uncorrected visual acuity, corneal topography, wavefront aberrometry, retinal image quality, contrast sensitivity, and biomechanical response of the cornea. Patients completed subjective questionnaires at each follow-up.
Clinical results demonstrate that SBK provides quicker visual recovery, although the data suggest that the 3- and 6-months results are similar in terms of visual outcomes. Reichert Ocular Response Analyzer results demonstrate that its impact on the cornea is similar to PRK.
This study indicates that SBK provides the visual recovery of a LASIK procedure with the Optical Response Analyzer results similar to PRK.