Keratectomy In Rabbits Research Articles

Cell Biology of Spontaneous Persistent Epithelial Defects After Photorefractive Keratectomy in Rabbits.

To evaluate wound healing in rabbit corneas that developed a spontaneous persistent epithelial defect (PED) after photorefractive keratectomy (PRK). Forty-eight 10- to 15-week-old female New Zealand White rabbits weighing 2.5 to 3.0 kg underwent either -3 diopter (D) or -9 D PRK to generate a series of corneas to study wound healing after injury. During that series, seven corneas developed a PED detected with 1% fluorescein staining at a slit lamp that either did not have epithelial closure by 1 week after surgery or subsequently had the closed epithelium break down to form a PED 2 to 3 weeks after surgery. The corneas had slit-lamp photography, with and without 1% fluorescein, and were removed from the normal PRK series. Each PED cornea was evaluated using immunohistochemistry for the myofibroblast marker α-smooth muscle actin (α-SMA), keratocyte marker keratocan, and mesenchymal cell marker vimentin, as well as basement membrane components perlecan and collagen type IV. All seven corneas that had PRK with a PED, even the two evaluated at only 1 week after PRK, had α-SMA-positive myofibroblasts populating the anterior stroma within the PED, along with comingled α-SMA-negative cells that were likely corneal fibroblasts and possibly bone marrow-derived fibrocytes. Both perlecan and collagen type IV accumulated in the anterior stroma of the epithelial defects without an epithelial basement membrane, likely produced by corneal fibroblasts to modulate transforming growth factor-β entering the stroma from the tears and peripheral epithelium. Corneas with a PED that occurred following PRK (a procedure that produces a transient neurotropic state in the cornea) had myofibroblasts populating the superficial stroma within the epithelial defect as early as 1 week after the surgery. Pharmacologic treatments that trigger myofibroblast apoptosis, including topical losartan, could facilitate decreased scarring fibrosis in corneas with a PED.

Effects of Rapamycin on corneal haze after photorefractive keratectomy in rabbits

Effects of Rapamycin on corneal haze after photorefractive keratectomy in rabbits

The Effect of Topical Substance-P Plus Insulin-like Growth Factor-1 (IGF-1) on Epithelial Healing After Photorefractive Keratectomy in Rabbits.

PurposeTo determine whether topical Substance-P (SP) plus insulin-like growth factor-1 (IGF-1) can improve corneal healing after photorefractive surface ablation in a rabbit.MethodsAfter a 9.0-mm corneal de-epithelialization using a combination of chemical (18% alcohol) and mechanical debridement, excimer photorefractive surface ablation was performed bilaterally in eight rabbits (16 eyes) with an 8.0-mm ablation zone and 70-μm depth. The right eye was treated with SP (250 μg/mL) and IGF-1 (25 ng/mL) in hyaluronic acid, one drop twice a day, and the other eye treated with only hyaluronic acid. The epithelial healing process was documented photographically twice a day until healing was complete. Six rabbits were sacrificed 6 weeks after photorefractive keratectomy (PRK) and corneas examined histologically.ResultsSeven of eight rabbit eyes treated with SP/IGF-1 healed in a shorter time than the untreated eye. For rabbit #6, both eyes healed at the same time. The average healing time (total time until wound closure) for the treated eyes was 99 hours, while the average healing time for the untreated eyes was 170 hours (P = 0.0490). A persistent epithelial defect was found in two of the nontreated eyes but none in the treated eyes. Corneal pathology showed some degree of epithelial separation in the central corneal wound in three out of six nontreated eyes and in just the treated eye of rabbit #6.ConclusionTopical SP plus IGF-1 increases the epithelial healing rate after PRK. There may have been beneficial effects upon cell adhesion as well.Translational RelevanceBetter and faster healing.

Topical 1% Nalbuphine on corneal sensivity and epitheilization after experimental lamellar keratectomy in rabbits

The present study was aimed to evaluate the effects of topical 1% nalbuphine on corneal sensitivity and re-epithelialization, after lamellar keratectomy in rabbits. All protocols were approved by the Animal Care Comission of São Paulo State University (Protocol 028793-08) and were conducted in accordance with the Institutional Animal Committee and the Association for Research in Vision and Ophthalmology (ARVO) statement for the use of animals in research. Surgeries were performed on the left eye (Nalbuphine Group) and on the right eye (Control Group). Two groups were formed (n=10) and corneas received either 30µl of 1% nalbuphine (NG) or 30µl of 0,9% saline (CG). Treatments occurred at 7, 11, 15 and 19 hours. After the surgery, the corneas were stained with fluorescein and photographed daily; corneal touch threshold (CTT) was assessed with Cochet-Bonnet aesthesiometer, at 7 and 19 hours, 20 minutes after treatments. Data were statistically compared with repeated measures ANOVA and Bonferroni post-hoc test, and T test (P<0.05). Average ±SD time for corneal re-epithelialization was 7.40±0.47 days (NG) and 8.90±0.31 days (CG) (P=0.11). The results showed that the diameter of the keratectomized area and CTT did not change significantly between both groups (P>0.05); however, a higher area under the curve for both parameters was observed in the NG (2771), in comparison to CG (2164). Topical 1% nalbuphine did not change significantly corneal sensitivity and re-epithelialization, after experimental lamellar keratectomy in rabbits.

Expression of matrix metalloproteinases, type IV collagen, and interleukin‐10 in rabbits treated with morphine after lamellar keratectomy

To study the effects of topical administration of 1% morphine on corneal analgesia in rabbits submitted to lamellar keratectomy and to assess the expression of matrix metalloproteinase-1, metalloproteinase-2, metalloproteinase-9 (MMPs), type IV collagen, and interleukin-10 (IL-10) during the treatment. Morphine group (MG) received 50 μL of topical 1% morphine four times daily, while the control group received saline instead. Corneal touch threshold (CTT) and the wound area were assessed until corneal healing. Corneal samples were processed for routine histology, immunohistochemistry, zymography, and ELISA. Following keratectomy, CTT increased significantly from 6 to 96 h time points. Mean corneal re-epithelization rate and scores of leukocyte infiltration did not differ significantly between treatment groups. Immunolabeling pattern for MMP-1, MMP-9, and type IV collagen was similar in both treatment groups. In the MG, zymography indicated significantly higher levels of active MMP-2 on days 6 and 12; and in the latent MMP-9, on days 3 and 6, and in the active MMP-9, on day 6. Latent MMP-2 and MMP-9, and active MMP-9 decreased to values close to those of healthy corneas on day 12, but levels of active MMP-2 remained significantly elevated in the MG. IL-10 levels measured on days 1-6 were reduced as compared to those of healthy corneal tissue and returned to levels close to those of healthy corneas on day 12. Topical morphine promoted corneal analgesia for up to 4 days and did not delay corneal re-epithelization. The re-establishment of MMPs and IL-10 to levels close to baseline values at the end of the study and the expression of type IV collagen in both groups reinforce that, with caution, 1% morphine can be used after lamellar keratectomy in rabbits.

Reducing peak corneal haze after photorefractive keratectomy in rabbits: Prednisolone acetate 1.00% versus cyclosporine A 0.05%

To compare the effects of topical cyclosporine A 0.05% (Restasis) with those of prednisolone acetate 1.00% (Pred Forte) on corneal haze after photorefractive keratectomy (PRK). Gavin Herbert Eye Institute, University of California, Irvine-Orange, California, USA. Experimental study. After -9.00 diopter PRK, 15 rabbits were divided into 3 groups and treated for 4 weeks with prednisolone acetate 1.00% or cyclosporine A 0.05% or neither (control). Corneal haze was measured by in vivo confocal microscopy preoperatively and 2, 4, 6, 8, and 12 weeks postoperatively. At 12 weeks, the corneas were evaluated for collagen organization by ex vivo 2-photon second-harmonic generation and stromal cell density. Corneal haze was significantly less in the prednisolone acetate group than in the cyclosporine and control groups during the first 6 weeks postoperatively (P<.02). At 8 weeks, there was no significant difference between the 3 groups. There was no significant difference in haze between the cyclosporine and control groups at any time. The stroma was also significantly thinner in the prednisolone acetate group than in the other groups for the first 4 weeks postoperatively (P<.02). Second-harmonic generation scar thickness measurements at 12 weeks were not significantly different between the groups, although the prednisolone acetate group tended to have lower stromal cell density. Cyclosporine A 0.05% had no effect on wound healing after PRK, while prednisolone acetate 1.00% significantly reduced peak corneal haze but had no effect on long-term corneal haze after discontinuation of the drug.

Refractive surgery using CustomVis Solid State Laser 213nm. One year post‐op clinical evaluation supported by an experimental study

Abstract Purpose To report our experimental and clinical findings using a solid state laser system 213nm in refractive surgery. Methods 40 pigmented rabbits underwent myopic PRK using a solid state laser in one eye and excimer laser in the fellow eye. Rabbits were sacrificed immediately after the ablation, at 7days and at one, 3 and 12months after surgery. Corneal tissue was preserved for Light, Scan and Transmission electron microscopy. 60 patients (115eyes) underwent PRK [mSEQ ‐4.43±1.81D] and 20 patients (40eyes) LASIK [mSEQ ‐5.55±1.52D] using CustomVis quintupled Nd:YAG Solid State laser at 213nm. Results Experimental study: Immediately after the ablation, LM, scan and TEM microscopy revealed relatively smooth ablation surfaces in both groups. At 1,3 and 12m postoperatively, there was tissue appearance, typical for post‐PRK samples, of all corneal layers in both groups. Clinical study: At one year follow‐up for the PRK mRSEQ was ‐0.11±0.52D and mUCVA was 1.03. 39% gained more than 1 line, 48% had no loss or gain of lines and 12% lost more than 1 line. For the LASIK group at 12m the mRSEQ was 0.42±0.70D and the mUCVA was 0.94; 61% of eyes gained more than 1 line, 33.3% of eyes gained had no loss of lines and 5.6% of eyes lost more than 1 line. 67% of eyes were in the +/‐ 0.25 and 72% of eyes were in the +/‐0.5 interval for the Lasik patients. For the PRK patients 49% of eyes were in the +/‐ 0.25 and 80% of eyes were in the +/‐0.5 interval for the Lasik patients. Conclusion Photorefractive keratectomy in rabbits with ultraviolet solid state and excimer laser revealed similar histopathological findings up to one year postoperatively. PRK and LASIK were both effective and safe in the correction of myopic astigmatism.

Effects of Autologous Serum Eye Drops on Corneal Wound Healing After Superficial Keratectomy in Rabbits

: To study the effects of topically applied autologous serum on the wound healing process of mechanically produced corneal ulcers. : A superficial keratectomy was done in 1 eye from each of 28 rabbits, using a corneal trephine. Four groups of 7 rabbits were treated topically 4 times a day with nondiluted autologous serum; diluted autologous serum (20%); unpreserved pharmaceutical tear substitute; and physiologic saline. The saline-treated group served as a control. The healing of the ulcers was followed on a slit-lamp biomicroscope regarding its size, infiltration, and neovascularization on alternate days up to day 10 with and without fluorescein staining. : Autologous serum significantly accelerated the corneal wound healing process in both concentrations compared with either the unpreserved pharmaceutical tear substitute or physiologic saline solutions, but the process was faster with the nondiluted concentration. : Autologous serum eye drops could be used as a corneal wound healing adjuvant in mechanical corneal ulcers. To accelerate the wound healing process, the blood-derived factors were brought externally to the avascular cornea through autologous serum eye drops. The importance of the vascular supply on the wound healing process of vascular tissues is well known, and this study considers the benefit of blood-derived factors on the healing process of cornea.

Application of Newly Developed Amniotic Membrane Ointment for Photorefractive Keratectomy in Rabbits

We developed amniotic membrane ointment (AMO), and the effect of instilling the AMO after photorefractive keratectomy (PRK) was investigated with respect to inflammatory cell infiltration into the corneal stroma, apoptosis of keratocytes, and suppression of lipid peroxidation of cellular walls. The PRK procedure was performed on both eyes of 10 white rabbits. One eye of each rabbit (the experimental eye) was instilled with the AMO and the other eye of the rabbit (the control eye) with a base ointment 0, 8 and 16 h after the PRK procedure. Corneal specimens were collected 24 h after the PRK procedure. Hematoxylin-eosin stain and TUNEL assay were conducted to demonstrate polymorphonuclear and apoptotic cells, respectively. To assess lipid peroxidation, immunohistochemical staining with an antibody to malondialdehyde was undertaken. Compared to the control, the cornea instilled with the AMO had significantly less polymorphonuclear cells infiltrating into the corneal stroma as well as keratocytes subjected to apoptosis. These corneas also showed a significantly less extent of lipid peroxidation than the control. These data support that instillation of the AMO effectively reduced the recruitment of polymorphonuclear cells, the induction of apoptosis in keratocytes, and lipid peroxidation induced by PRK. Thus, this study could provide basic data on the clinical application of the AMO in the days ahead.

Effect of Homoharringtonine on corneal haze after excimer laser photorefractive keratectomy in rabbits.

To evaluate the inhibiting effect of Homoharringtonine (HHT) on the corneal haze after excimer laser photorefractive keratectomy (PRK) in rabbits. 18 healthy rabbits which underwent PRK were randomly divided into three groups (A, B and C). The refractive degree of ablation was - 10.0DS in each group. Group A was locally treated with a piece of filter paper soaked with 1 mg/mL HHT for 5 min, and then the entire cornea was repeatedly irrigated with balance solution; Group B was dropped with 0.1 mg/mL HHT after PRK for 3 months; Group C was the control group. Corneal haze, histopathology, response, ect. were investigated. The corneal haze was significantly less in group A, while the difference between group B and group C was insignificant. Keratocytes and fibrocytes in corneal stroma were more active up to 3 months in group B and group C. Intraoperative use of topical HHT can reduce corneal haze after PRK in rabbits.

Decreased keratocyte death after laser-assisted subepithelial keratectomy and photorefractive keratectomy in rabbits

To compare keratocyte loss in the corneal stroma after laser-assisted subepithelial keratectomy (LASEK) and photorefractive keratectomy (PRK) in rabbits. Department of Ophthalmology, University of Essen, Essen, and the Institute of Anatomy, University of Bochum, Bochum, Germany. Laser-assisted subepithelial keratectomy and PRK were performed in rabbits and studied 1, 3, 10, and 20 days after surgery. Excimer photoablation was done unilaterally with a 6.0 mm ablation zone and an 80 microm depth, equivalent to -6.0 diopters. Keratocyte death was analyzed using DNA fragmentation-detecting terminal deoxynucleotidyl transferase deoxy-UTR-nick end labeling (TUNEL) assay and transmission electron microscopy. Numerous TUNEL-positive keratocytes occurred 1 day after PRK; the number decreased significantly after 3 days. After LASEK, significantly fewer TUNEL-positive keratocytes were noted at the early time points (P<.001 at 1 day; P< or =.05 at 3 days). At 10 days, the number of TUNEL-positive keratocytes decreased in both groups but remained significantly higher after PRK than after LASEK (P<.001). Twenty days after both procedures, no significant signs of keratocyte death were found in the corneal stroma. Transmission electron microscopy revealed few apoptotic keratocytes after LASEK. After PRK, apoptotic keratocytes, characterized by chromatin condensation, apoptotic bodies, and cell shrinkage, were scattered in the stroma. The ultrastructural findings confirmed the results obtained with the TUNEL assay. Laser-assisted subepithelial keratectomy induced significantly less apoptotic keratocyte death than PRK and promoted wound healing in the acute phase after photoablation. This procedure may offer the possibility of treating higher myopia with a decreased risk for developing wound healing-related complications known to occur after PRK.

Effect of homoharringtonine on the corneal haze after excimer laser photorefractive keratectomy in rabbits

To evaluate the inhibiting effect of Homoharringtonine HHT) on the corneal haze after excimer laser photorefractive keratectomy (PRK) in rabbits. 18 healthy rabbits which underwent PRK were randomly divided into three groups (A, B and C). The refractive degree of ablation was -10. 0DS in each group. Group A was locally treated with a piece of filter paper soaked with 1 mg/mi HHT for 5 min, and then the entire cornea was repeatedly irrigated with balance solution;Group B was dropped with 0.1 mg/mL HHT after PRK for 3 months; Group C was the control group. Corneal haze, histopathology, response, ect. were investigated. The corneal haze was sig nificantly less in group A, while the difference between group B and group C was insignificant.Keratocytes and fibrocytes in corneal stroma were more active up to 3 months in group B and group C. Intraoperative use of topical HHT can reduce corneal haze after PRK in rabbits.

Fluoroquinolone therapy in multiple-drug resistant staphylococcal keratitis after lamellar keratectomy in a rabbit model

PurposeTo assess the effectiveness of a fourth-generation fluoroquinolone for prophylaxis against multiple drug-resistant staphylococcal keratitis after lamellar keratectomy in a rabbit model. DesignExperimental study. MethodsTwenty-eight New Zealand white rabbits underwent unilateral lamellar keratectomy using a manual microkeratome followed by the placement of 1,000 colony-forming units (CFUs) of log-phase Staphylococcus aureus bacteria under each flap. Eyes (seven in each group) were randomized and treated with one of the following agents: sterile balanced salt solution, gatifloxacin (0.3%), ciprofloxacin (0.3%) or levofloxacin (0.5%) immediately and 6, 12, and 18 hours after surgery. Inflammation was graded by two masked observers at 24 and 48 hours, and the presence or absence of infectious infiltrates was determined. The means and standard deviations were calculated, and differences among the groups were statistically analyzed. ResultsThere were no flap complications encountered during surgery. Eyes treated with ciprofloxacin, levofloxacin, and balanced salt solution developed infectious infiltrates in five of seven eyes per group. Gatifloxacin-treated eyes did not develop clinical infection and exhibited lower mean inflammation scores (P < .01 compared with the other groups). ConclusionsThe fourth-generation fluoroquinolone, gatifloxacin, is an effective prophylaxis against the development of keratitis after lamellar keratectomy in rabbits with an organism resistant to methicillin, levofloxacin, and ciprofloxacin.

Effects of Various Eye Drops on Corneal Wound Healing after Superficial Keratectomy in Rabbits

Purpose: The effects of various eye drops on corneal wound healing, particularly in the subepithelial haze area, were investigated histologically following superficial keratectomy in rabbits. Methods: Mechanical superficial keratectomy was performed in rabbit eyes. Tranilast, betamethasone, hyaluronic acid, and diclofenac eye drops were administered after the procedure. Physiological saline was used as a control. Corneas were excised 1, 2, 3, and 4 weeks after keratectomy, labeled with 3H-thymidine or 3H-proline, and subjected to autoradiography. Results: In the control and diclofenac groups, corneal haze occurred 3 weeks after keratectomy. Histological examination revealed an accumulation of proliferating keratocytes and active synthesis of collagen in the subepithelial area. In the tranilast and betamethasone groups, formation of corneal haze was reduced compared to the controls. The proliferation of keratocytes and the production of collagen in the corneal stroma were inhibited by these drugs. In the hyaluronic acid group also, corneal haze was decreased. In this group, although the proliferation of keratocytes was activated compared to the controls, abnormal accumulation of keratocytes in the subepithelial area was not detected. Conclusions: Tranilast and betamethasone decrease the formation of subepithelial haze by inhibiting keratocyte proliferation and synthesis of extracellular matrix in the corneal stroma. Hyaluronic acid, on the other hand, inhibits subepithelial haze by promoting physiologic wound healing.

Effects of Various Eye Drops on Corneal Wound Healing after Superficial Keratectomy in Rabbits

Effects of Various Eye Drops on Corneal Wound Healing after Superficial Keratectomy in Rabbits

Expression and Distribution of Extracellular Matrices during Corneal Wound Healing after Keratomileusis in Rabbits

We compared the corneal wound healing responses of keratomileusis and keratectomy in rabbits. A single pass of thin lamellar keratectomy was performed with a microkeratome in rabbits. The lenticule was repositioned with a hinge in one group and discarded in the other. With immunofluorescence techniques, we studied the appearance and distribution of fibronectin, fibrinogen and type III collagen at follow-up intervals from 1 h to 3 months. Fibronectin and fibrinogen began to deposit on the periphery of the denuded stroma 3 h after induced injury and diminished once reepithelialization had completed in both groups. In the corneas with attached lenticules, type III collagen was detected 7 days after surgery and lasted for at least 3 months. Type III collagen was detected only in the periphery of the interface and not in its center. These findings suggest that fibronectin and fibrinogen may play roles in epithelial healing after in situ keratomileusis in rabbits. Stromal healing of colla- gen seems to take place 7 days after keratomileusis and to last for several months. No deposits of new collagens in the center of the interface between lenticule and stromal bed may explain the optical clarity in the keratomileusis.

Differences in Keratocyte Apoptosis Following Transepithelial and Laser-scrape Photorefractive Keratectomy in Rabbits

Anterior stromal keratocyte cells undergo programmed cell death (apoptosis) in response to corneal epithelial injury. Keratocyte apoptosis may be an initiator of the corneal wound healing response that includes keratocyte proliferation and activation, as well as changes to the overlying epithelium, occurring following refractive surgical procedures such as photorefractive keratectomy (PRK). This study compared the effect of laser-scrape and transepithelial PRK on keratocyte apoptosis. Photorefractive keratectomy was performed in both eyes of 10 New Zealand white rabbits using the Summit Apex excimer laser. Surgery was performed using transepithelial PRK in one eye and laser-scrape PRK in the other. The central cornea was analyzed at 4 hours after surgery using a quantitative TUNEL assay that detects fragmented DNA characteristic of apoptosis. Hepatocyte growth factor (HGF) production by keratocytes was detected by immunocytochemistry. Average apoptotic cells per 400X microscopic field determined by 2 independent masked observers were 0.9 +/- 0.5 (scanning electron microscopy) and 0.2 +/- 0.2 in the transepithelial PRK group compared with 5.1 +/- 2.9 and 4.1 +/- 3.2 in the laser-scrape group. The difference between the two groups was statistically significant for both observers (P < .05, ANOVA). HGF was detected within keratocytes throughout the corneal stroma. Less HGF was detected in the anterior stroma in the laser-scrape group at 4 hours after surgery, consistent with more anterior keratocyte apoptosis in this group. Transepithelial PRK induced less anterior keratocyte apoptosis in rabbits than laser-scrape PRK. This suggests that transepithelial PRK could be useful in preventing or minimizing refractive regression and subepithelial scarring.

Effects of Synthetic Inhibitor of Metalloproteinase and Cyclosporin A on Corneal Haze after Excimer Laser Photorefractive Keratectomy in Rabbits

To evaluate the effects of synthetic inhibitor of metalloproteinase (SIMP) and cyclosporin A (CsA) on corneal haze after excimer laser photorefractive keratectomy (PRK) in rabbits, PRK was performed on 60 rabbits. They were randomized to one of four groups: group A which received topical SIMP, group B which received topical CsA, group C which received both SIMP and CsA, and group D which received vehicles. Another 16 rabbits did not undergo PRK and were randomized to one of four groups: group E which received topical SIMP, group F which received topical CsA, group G which received both SIMP and CsA, and group H which received vehicles. SIMP solution (1 mm) was instilled every two hours and 2% cyclosporin was instilled four times a day, this was carried out for as long as 6 weeks after surgery. At one, two, four, and six weeks after surgery, slit lamp examination was performed with haze gradings recorded, and corneal specimens were obtained from groups A, B, C, and D. In groups E–H, all rabbits were killed after six weeks of eyedrops instillation. Light microscopy and immunohistochemistry for collagen types III, IV, and VI were performed on the specimens obtained. Slit lamp examination and light microscopy revealed that SIMP significantly reduced corneal haze after PRK, but CsA did not. Immunohistochemistry revealed that deposition of types III and IV collagen was detected in ablated area in groups A–D, and SIMP reduced the frequency of positive staining for type III collagen. In groups E–F, corneas were normal. These findings suggest that SIMP significantly reduced corneal haze and the synthesis of type III collagen after excimer laser PRK in rabbits.

Effect of topical anti-transforming growth factor-β on corneal stromal haze after photorefractive keratectomy in rabbits

Purpose: To determine the relationship between anti-transforming growth factor-β (anti-TGF-β) antibodies and the amount of corneal stromal haze after excimer laser photorefractive keratectomy (PRK).Setting: Wills Eye Hospital, Philadelphia, Pennsylvania, USA.Methods: Nineteen rabbits had bilateral PRK. Dichlorotriazinyl fluorescein was used to stain the exposed stroma; all rabbits were then treated with antibiotic ointment for 4 days. Ten rabbits were randomized to treatment with topical anti-TGF-β1, -β2, and -β3 antibody 50 gg three times a day for 4 days; the others received diluent three times a day for 4 days. Stromal haze was graded weekly for 8 weeks on a 0 to 4+ scale. At the end of the study, all corneas were examined histopathologically.Results: All treated eyes developed appreciable haze. Seven control rabbits and one antibody-treated rabbit had an epithelial erosion (P = .00001). Antibody-treated rabbits had significantly less haze at 3, 4, and 5 weeks (right eyes) and 3, 4, 5, 7 and 8 weeks (left eyes) (P < .05). Histopathology and fluorescence microscopy showed subepithelial collagen deposition consistent with clinical haze.Conclusions: Topical anti-TGF-β antibody reduced stromal haze after PRK in the rabbit model and may be clinically beneficial in humans.

Mitomycin C reduces scar formation after excimer laser (193 nm) photorefractive keratectomy in rabbits.

Sixteen eyes of eight rabbits were randomised to either mitomycin C or Balanced Salt Solution (BSS) application after photorefractive keratectomy (PRK). Regular examinations of wound healing and haze were performed with the slit lamp. The animals were killed between 1 and 26 weeks after treatment, and the corneas examined by light and electron microscopy. While the grade of haze showed no relevant differences between the two groups, scar tissue was found histologically in the mitomycin group in only 1 of 8 corneas compared with 5 of 8 in the BSS group. A marked reduction in keratocytes in all mitomycin-treated corneas and a normal density of keratocytes in the BSS group was observed. Mitomycin reduced the number of keratocytes in the treated corneas, leading to less scar formation but not to a reduction in haze. Since no morphological correlate has been found, haze remains unexplained in the mitomycin-treated corneas.