Impact of short-term versus long-term topical steroids on corneal neovascularization after non-high-risk keratoplasty

PURPOSE: To analyze incidence and extent of corneal neovascularization (CN) after non-high-risk keratoplasty and to find out whether duration of postoperative topical steroid therapy (6 vs 12 months) affects CN, corneal endothelial cell count, pachymetry, aqueous flare values, and best-corrected visual acuity at 1 year after keratoplasty. METHODS: Patients of the prospective Erlangen non-high-risk keratoplasty study with available high-quality corneal photographs taken preoperatively and 1 year later were analyzed (n=136). Corneal photographs were evaluated by two independent observers in a standardized semiquantitative fashion. Slides were projected with 100x magnification and corneal vessels classified into five grades with regard to the limbus, sutures and host-graft junction in each of 12 corneal sectors. Incidence and extent of CN after keratoplasty and relation to short-term (0-6 months) versus long-term (0-12 months) postoperative topical steroid therapy were analyzed. The effect of duration of topical steroid therapy on corneal endothelial cell count, pachymetry, aqueous flare values, and best corrected visual acuity was also analyzed. Of the 136 patients, 69 (51%) were randomly assigned to short-term and 67 to long-term topical prednisolone acetate 1%. RESULTS: Fifty-eight percent of patients (n=79) developed a CN within 1 year after keratoplasty in at least one corneal sector (mean 3.1 +/- 2.2, range 1-10). At 1 year after keratoplasty, only in 12% of these patients did at least one vessel reach the host-graft junction or grow into the donor cornea, whereas in 51% vessels were seen beyond the outer suture ends of the double running suture without reaching the host-graft junction. In 37%, capillaries were located between limbus and outer suture ends. New vessels usually pointed directly or indirectly to the outer suture ends and usually were located around the 12 o'clock and 6 o'clock positions. There was no significant difference regarding incidence and extent of CN 1 year after keratoplasty between the long-term and the short-term group. Duration of topical steroid therapy had no significant effect on corneal endothelial cell count and thickness, aqueous flare values and best-corrected visual acuity at 6 and 12 months postoperatively (only at 12 months, corneas in the long-term treatment group were slightly thicker; P=0.03). Interobserver correlation of vessel assessment was 0.77 (Kendall's tau B). CONCLUSIONS: CN is a common phenomenon after non-high-risk keratoplasty. New vessels rarely reach the host-graft junction, most commonly develop from the 6 o'clock and 12 o'clock positions and are usually located between epithelium and Bowman's layer (i.e., at the level of the superficial suture). The direction of vessel growth from the limbus towards the outer suture ends suggests release of angiogenic factors in this area. Prolongation of topical steroid therapy after non-high-risk keratoplasty beyond 6 months in this study did not significantly influence incidence and extent of CN, corneal endothelial cell count, aqueous flare values and best-corrected visual acuity observed 1 year after keratoplasty.     

Corneal neovascularization after nonmechanical versus mechanical corneal trephination for non-high-risk keratoplasty

PURPOSE: To analyze the influence of mechanical versus nonmechanical trephination of donor and host corneas on superficial, peripheral corneal neovascularization occurring after non-high-risk keratoplasty. METHODS: Patients of the prospective Erlangen non-high-risk keratoplasty study with standardized corneal photographs taken preoperatively and 1 year later were analyzed (n = 184). Slides of these photographs were projected (magnification x100) and corneal vessels graded in a standardized semiquantitative fashion into five categories with regard to limbus, sutures, and host-graft junction in each of 12 corneal sectors. Degree (total increase of grades in the 12 sectors) and maximal extent of corneal neovascularization (maximal centripetal extension of blood vessels) were analyzed. In 32 patients mechanical (17%) and in 152 nonmechanical trephination of host and donor tissue was performed (193-nm excimer laser, 83%). Statistical analysis was done using Fisher's exact and Mann-Whitney test. RESULTS: Corneal neovascularization within the first postoperative year was lower in the nonmechanical [73 of 152 (48%)] compared with mechanical trephination group [24 of 32 (75%); p< 0.01; Mann-Whitney test]. Maximal extent of neovascularization (i.e., vessels reaching the interface or growing beyond) was not yet significantly different between nonmechanical (8%) and mechanical (17%) trephination (p = 0.074). CONCLUSIONS: Nonmechanical trephination using the 193-nm excimer laser in non-high-risk keratoplasties might reduce corneal neovascularization occurring within the first postoperative year. This indicates that in the non-high-risk setting, development of postoperative corneal neovascularization may be affected by the trephination technique and subsequent wound-healing response.     

Corneal relaxing incision to aid contact lens fitting for post-penetrating keratoplasty patients

Computerized video keratography has greatly enhanced our understanding of post-penetrating keratoplasty (PK) corneal topography. Tight and loose suture points, irregular areas of the graft-host junction, and asymmetric flat and steep areas can be clearly defined by corneal mapping. Frequently, corneal transplant eyes show irregular, asymmetric, nonorthogonal astigmatism caused by uneven wound healing and suture closing. Corneal relaxing incisions offer a viable alternative to returning the post-PK cornea to a more symmetrical topography. Corneal topographical mapping can provide the appropriate shape information necessary to guide the placement of corneal relaxing incisions on the corneal surface.     

Effects of corneal neovascularization on the manifestations of Avellino corneal dystrophy (granular corneal dystrophy type II)

PURPOSE: To evaluate the corneal deposits of Avellino corneal dystrophy (ACD) in patients with corneal neovascularization from pterygium or phthisis bulbi as a way of understanding the pathogenesis of ACD. METHODS: Five patients with ACD with pterygium, 10 patients with ACD (age >50 years) without pterygium, 1 patient with ACD with phthisis bulbi with corneal neovascularization, and 1 patient with ACD with phthisis bulbi without corneal neovascularization were examined. The corneal deposits of all patients were assessed by slit-lamp examination and reviewed with biomicroscopic photographs. The distance between the limbus and the nearest corneal opacities was measured. RESULTS: In eyes with vascularized nasal pterygia, there was a granule-free zone adjacent to the advancing edge of the pterygium so that the distance between the nasal limbus and the most nasally located granule exceeds that of the distance between the limbus and the closest granule elsewhere on the cornea. In patients with ACD with phthisis bulbi, no granular deposits were observed in the cornea with neovascularization, but there were deposits in the cornea without neovascularization. CONCLUSION: Corneal neovascularization prevents the deposition of corneal opacities in patients with ACD.     

角膜共焦显微镜早期诊断兔高危角膜移植排斥反应的价值

目的:角膜共焦显微镜检查对兔碱烧伤角膜移植排斥反应进行研究,找寻排斥反应早期诊断的客观指标。方法:制作兔角膜碱烧伤模型,36d后行穿透性角膜移植,于角膜移植术后4,9,14,21~28d诊断排斥反应时,角膜共焦显微镜检查角膜。结果:排斥反应时角膜共焦显微镜检查见角膜植片炎性细胞浸润,角膜细胞丢失,新生血管生长。结论:角膜共焦检查有助于早期诊断排斥反应。     

Electrolytic removal of recurrence of granular corneal dystrophy

AIMS: To report the efficacy of corneal electrolysis for the treatment of recurrent corneal opacities at the subepithelial region or at the host-graft interface of the stroma in granular corneal dystrophy (GCD). METHODS: In patients with recurrences of opacities at the host-graft interface of the stroma after lamellar keratoplasty, the deep aspect of the graft was partially separated from host tissue to expose the deposits. The graft was everted, and electrolysis was applied directly to remove the deposits attached to both surfaces of the host and the graft. Then the graft was returned to its place and sutured. In patients with diffuse subepithelial opacities following penetrating keratoplasty, electrolysis was applied directly to the corneal surface. RESULTS: Deposits in the subepithelial region or at the host-graft interface of the stroma disappeared following treatment, and vision recovered. However, GCD recurred 2-3 years after the treatment. CONCLUSIONS: Corneal electrolysis is a simple, easy, and inexpensive way to remove deposits that recur after lamellar or penetrating keratoplasty for GCD.     

Classification of corneal topography after penetrating keratoplasty

Background: Semiquantitative classification of corneal topography after penetrating keratoplasty has the potential for focusing information about the areal dioptric power of the cornea. The purpose of this study was to objectify the procedure of manual semiquantitative classification using a Fourier transform of corneal topography power data and to correlate both methods. Patients and methods: Fifty patients each (30 keratoconus, 20 Fuchs dystrophy) underwent nonmechanical trephination (excimer laser MEL60, Aesculap-Meditec, Jena) in penetrating keratoplasty. All procedures (7.5-mm trephination diameter in Fuchs, 8.0 mm in keratoconus, double-running 10–0 nylon suture) were done by one surgeon. Pre-, intra- and postoperative treatment were identical. At the follow-up examinations, the keratometric astigmatism, qualitative and quantitative criteria of the automatic videokeratography, visual acuity and refraction were assessed. Corneal topography was classified both manually and based on Fourier coefficients. Results: After a mean follow-up of 24 ± 5 months, keratometric net astigmatism was 3.0 and 2.7 D with keratoconus and Fuchs dystrophy. Corneal topography analysis showed a higher orthogonality of the bow-tie shape and less asymmetry between opposite hemimeridians with increasing follow-up after keratoplasty. The semiquantitative classification showed a statistically significant correlation with the classification based on Fourier coefficients, especially with higher astigmatism and after suture removal (P = 0.04/0.01 before/after suture removal). Discussion: After nonmechanical trephination, the semiquantitative classification of corneal topography can be synthetized using Fourier analysis of corneal dioptric power data. In the future, this method may be favored for prediction of potential best-corrected visual acuity after penetrating keratoplasty.      

Corneal electrolysis for recurrence of corneal stromal dystrophy after keratoplasty

AIMS: To evaluate corneal electrolysis as a treatment for recurrent diffuse corneal opacities at the host-graft interface of the stroma or at the subepithelial region in two types of granular corneal dystrophy (GCD). METHODS: Recurrence developed at the host-graft interface of the stroma after lamellar keratoplasty in a patient with Avellino corneal dystrophy (ACD). At surgery, the deep aspect of the graft in this patient was partially separated from host tissue to expose the deposits, with one third of the host-graft junction left intact. The graft was everted, and electrolysis was applied directly to remove the deposits attached to both surfaces of the host and the graft. Then the graft was returned to its place and sutured. In two patients with homozygous ACD and one patient with the superficial variant of GCD, diffuse subepithelial opacities developed following penetrating keratoplasty. Electrolysis was applied directly to the corneal surface. RESULTS: Deposits at the host-graft interface of the stroma and in the subepithelial region disappeared following treatment, and vision recovered in all patients. CONCLUSIONS: This method is a simple, easy, and inexpensive way to remove deposits that recur after lamellar or penetrating keratoplasty.     

Activation of ocular surface mast cells promotes corneal neovascularization

PurposeMast cells, historically known for their effector function in the induction of allergic diseases, reside in all vascularized tissues of the body in particular proximity to blood and lymphatic vessels. As neighboring sentinel cells to blood vessels, mast cells have been associated with angiogenesis. Here we assess the direct contribution of mast cells to neovascularization at the ocular surface.MethodsCorneal neovascularization was induced by placing a single figure-of-eight intrastromal suture 1 mm from the limbus in mast cell-deficient (cKit^W-sh), C57BL/6, and Balb/c mice. Corneas were harvested at 6 h post-suture to quantify cKit⁺FcεR1⁺ mast cells using flow cytometry and tear wash was collected within 6 h to measure β-hexosaminidase and tryptase. Neovascularization was assessed using slit-lamp biomicroscope and immunohistochemistry analysis of corneas harvested on day 4 post-suture. To investigate the effects of mast cells on blood vessel growth, mast cells were co-cultured with vascular endothelial cells (VECs), and tube formation and proliferation of VECs were measured. 2% cromolyn was administered locally to inhibit mast cell activation in vivo.ResultsPlacement of corneal suture activates ocular surface mast cells, which infiltrate into the cornea adjacent to new vessels. Mast cell-deficient mice develop significantly fewer new vessels following suture placement. Mast cells directly promote VEC proliferation and tube formation, partly through secreting high levels of VEGF-A. Pharmacological inhibition of mast cell activation results in significantly less corneal neovascularization.ConclusionOur data demonstrate that ocular surface mast cells are critical to corneal neovascularization, suggesting mast cells as a potential therapeutic target in the treatment of corneal neovascularization.     

Wavelet representation of corneal topography data after nonmechanical penetrating keratoplasty--a clinical study

BACKGROUND: Corneal surface irregularities may limit the visual outcome after penetrating keratoplasty (PK). Corneal topographers mainly render empirically derived and system-specific statistical indices for characterization of superficial inhomogeneities which may lack clinical evidence and make inter-system comparisons difficult. The purpose of this study was to detect and quantify focal surface irregularities of the cornea after nonmechanical PK by 2-dimensional wavelet decomposition based on corneal topography data. PATIENTS AND METHODS: Our study included 15 patients with keratoconus and 10 patients with Fuchs' dystrophy with all-sutures-out after penetrating keratoplasty. For trephination we used the excimer laser MEL60 (Aesculap-Meditec, Germany) (7.5/7.6 mm diameter in dystrophies, 8.0/8.1 mm in keratoconus, double-running 10-0 nylon suture). After suture removal a complete ophthalmological examination including OrbScan topography analysis (Orbtec, USA) was performed. The refraction data were extracted via "data recorder" and decomposed using 2-dimensional wavelet analysis methods (Daubechies-4-wavelets on five scales of resolution). Corneal irregularities were quantified (scale 1 = fine details to scale 5 = coarse details). RESULTS: All detail coefficients (horizontal, vertical and diagonal) correlated statistically significant with the "Irregular Astigmatism" provided by the OrbScan-system (p < 0.05). In scale 3 and 4 a relative maximum of the wavelet detail coefficients occurred, whereas the coefficients at scale 2 and 5 were significantly smaller. The horizontal and vertical detail coefficients correlated significantly inversely with the best-corrected visual acuity (p < 0.04). All detail coefficients were significantly lower in the patient group with keratoconus compared to Fuchs' dystrophy. CONCLUSIONS: Wavelet decomposition of corneal topography refraction data allows an analytical isolation and quantification of focal corneal superficial irregularities. This algorithm is independent of the currently used topography system and allows a smoothing of the raw data set adapted to scale of resolution and data compression.     

Surgery-related factors influencing corneal neovascularization after low-risk keratoplasty

PURPOSE: To identify the speed of corneal neovascularization (CNV) after penetrating keratoplasty (PK) and to evaluate the influence of surgery-related factors on postkeratoplasty CNV in keratoconus patients. DESIGN: Prospective, longitudinal, observational, case series study. METHODS: All consecutive primary PKs performed for keratoconus by four experienced surgeons between January 1, 2000 and December 31, 2002 at our department were included (n=66 patients). Standardized corneal photographs taken preoperatively and at 6 weeks, 3, 6, 12, 18, and 24 months postoperatively were evaluated. Limbus suture distance (LSD), limbus graft distance (LGD), inner suture angle (ISA), and maximal extension of CNVs in digitized pictures with 100-fold magnification were measured at each of the 16 suture turning points at every timepoint. RESULTS: Forty-four (67%) out of 66 corneal grafts developed some degree of CNV after PK, most commonly from around the 12 o'clock position. The mean speed of CNV growth was 114 microm/month with the fastest growth occurring during the first six weeks after PK. There was an inverse correlation between CNV and LSD, LGD, and ISA (all P<.001). Ninety percent of all CNVs developed with LSD<406 microm and with LGD<1000 microm. Superior limbal localization between 11 and 1 o'clock is an independent risk factor for postoperative neovascularization, too (P<.001). CONCLUSIONS: Small LSD, small LGD, and narrow stitching with small ISA were identified as potentially modifiable surgical risk factors for CNV after PK. The speed of CNV outgrowth was most pronounced in the first weeks after PK making early postoperative controls for CNV growth and initiation of antiangiogenic treatment important.     

Corneal argon laser photocoagulation for neovascularization in penetrating keratoplasty

Corneal argon laser photocoagulation (CALP) was used in 13 patients to treat deep stromal vascular ingrowth. Eight patients had undergone successful penetrating keratoplasty but had developed deep stromal vessels into the graft associated with signs of graft rejection, which did not improve with steroid treatment alone (group 1). After CALP, there was marked regression of the neovascularization with reversal of graft rejection in all eyes. Three additional patients with vascularized corneas, referred for penetrating keratoplasty, underwent CALP preoperatively with obliteration of the vessels (group 2). Two of these patients have since undergone keratoplasty and, in both, the grafts have remained avascular and clear over a 21-month follow-up. Two other patients with corneal injury and progressive corneal opacification and vascularization have also been treated with CALP (group 3). CALP may be a useful adjunct in the treatment of corneal neovascularization. Further clinical studies are needed to define its exact role.     

Photodynamic therapy with verteporfin in a rabbit model of corneal neovascularization

PURPOSE: To determine the efficacy of photodynamic therapy (PDT) with verteporfin (Visudyne; Novartis AG, Basel, Switzerland) for treatment of corneal neovascularization in a rabbit eye model. METHODS: Corneal neovascularization was induced in Dutch belted rabbits by placing an intrastromal silk suture near the limbus. Verteporfin was administered by intravenous injection at a dose of 1.5 mg/kg, and the pharmacokinetics of verteporfin distribution in the anterior segment or PDT-induced (laser energy levels 17, 50, and 150 J/cm(2)) regression of corneal blood vessels were then determined. To assess PDT-induced toxicity of the anterior segment, corneal and iris/ciliary body histology, and IOP were evaluated after PDT. RESULTS: Verteporfin accumulation in vascularized regions of the cornea and the iris/ciliary body tissue were time dependent and maximum levels achieved at 60 minutes after injection. In rabbits, PDT of corneal vessels using laser energy of 17 or 50 J/cm(2) resulted in 30% to 50% regression of corneal neovascularization; however, in these animals, a rapid regrowth of new blood vessels occurred between 3 and 5 days. In the rabbits receiving PDT using laser energies of 150 J/cm(2), the mean vessel regression was 56%. During the nine days of the laser therapy follow-up period, no vessel regrowth was observed in these rabbits. Histologic examination of the anterior segment after PDT (150 J/cm(2)) showed localized degeneration of the corneal blood vessels without observable change in other anterior segment structures. CONCLUSIONS: These results provide evidence that PDT can produce significant regression of neovascular corneal vessels with no observable toxicity to the anterior segments. However, the optimal laser energy necessary to induce long-term regression (150 J/cm(2)) was three times that used to treat choroidal neovascularization.     

In vivo confocal microscopy of subepithelial infiltrates in human corneal transplant rejection

PURPOSE: Corneal allograft rejection is the leading cause of penetrating keratoplasty failure in the first year after surgery. We report 2 cases of subepithelial infiltrates in corneal transplant rejection imaged by in vivo confocal microscopy. METHODS: Case report and review of relevant literature. RESULTS: Two subjects with subepithelial infiltrates in previously clear penetrating corneal transplants were assessed. In vivo confocal microscopy revealed focal accumulations of hyperreflective dendritic-like particles, postulated to represent Langerhans cells, at the level of the basal epithelium and Bowman membrane. Altered keratocytes with visible cytoplasmic processes were observed posterior to these foci. CONCLUSIONS: To our knowledge, these are the first reported cases of in vivo confocal microscopy appearance of corneal allograft rejection in humans. In vivo confocal microscopy may provide a valuable clinical tool to aid in the diagnosis of early corneal transplant rejection and in the differential diagnosis of other inflammatory conditions of the cornea.     

Influence of suture regularity on corneal astigmatism after penetrating keratoplasty

Purpose: To investigate whether suture regularity affects corneal astigmatism after keratoplasty. Methods: Twenty‐one patients undergoing penetrating keratoplasty for various corneal diseases were included in the study. The grafts were sutured in place using a single‐running Nylon 10‐0 suture, taking 24 bites. Immediately after surgery, standard calibrated images of the grafted eye were captured and stored. Using a dedicated image analysis programme, stitches and needle points were identified, and a number of suture regularity variables were calculated. Corneal topographic images were obtained before suture removal (12 months after surgery) and 3 months after suture removal (18 months after surgery). Topographic measures of astigmatism [surface regularity (SRI), surface asymmetry index (SAI) and simulated keratometric astigmatism] were calculated and correlated with the computed suture regularity variables. Results: The average stitch length was 3.04 ± 0.28 mm and the distance between the outer needle points was 2.53 ± 0.09 mm. The SRI was 1.26 ± 0.36 and the SAI was 1.59 ± 0.67 after 12 months; these decreased to 1.03 ± 0.48 and 0.92 ± 0.46 after 18 months, respectively. Corneal astigmatism was 6.38 ± 2.99 and 5.87 ± 3.13 dioptres after 12 and 18 months, respectively. Suture regularity did not affect SAI, SRI or corneal astigmatism significantly 12 months after surgery. Eighteen months after surgery (3 months after suture removal), the standard deviation on the original stitch length was found to significantly increase corneal astigmatism. In addition, the size of the counter‐clockwise angle between stitch and graft radian was correlated significantly with a lower SRI. Conclusion: The origin of corneal astigmatism after penetrating keratoplasty is multifaceted. Regular stitch length and stitch advancement on the surface appears to improve the optical quality of the graft after suture removal. Factors such as stitch depth, suture tension and variations in wound construction might also be important predictors of corneal astigmatism after penetrating keratoplasty.     

Sustained intraocular rapamycin delivery effectively prevents high-risk corneal allograft rejection and neovascularization in rabbits

PURPOSE: To evaluate the immunosuppressive and antiangiogenic activities of an intraocular rapamycin (RAPA) drug delivery system (DDS) in a rabbit model of high-risk penetrating keratoplasty. METHODS: Forty New Zealand White rabbits with corneal neovascularization underwent allograft cornea transplantation and were randomly divided into four groups: a control group, a glycolide-co-lactide-co-caprolactone copolymer (PGLC)-implanted group, a RAPA eye drop group, and a RAPA-PGLC DDS-implanted group. Graft survival, corneal neovascularization, and RAPA concentration in the aqueous humor were monitored for 90 days. Corneal grafts were also examined by in situ hybridization and immunohistochemistry for proinflammatory gene expression. RESULTS: In the control and PGLC groups, graft rejection occurred within 3 weeks of keratoplasty. In the RAPA eye drop and RAPA-PGLC groups, corneal rejection was significantly delayed, and neovascularization was markedly inhibited. Median graft survival times were 36 and >90 days in the eye drop and RAPA-PGLC groups, respectively. Mean RAPA concentrations in the aqueous humor were 10.7 ng/mL, 12.0 ng/mL, 9.2 ng/mL, and 7.0 ng/mL in the RAPA-PGLC group 2, 4, 8, and 12 weeks after surgery, respectively. By contrast, RAPA was undetectable in the aqueous humor in the eye drop group. High levels of IL-2R, MCP-1, TNF-alpha, and VEGF were detected in the corneal grafts of the control and PGLC groups but not in those of the RAPA-treated groups. CONCLUSIONS: RAPA-PGLC DDS and RAPA eye drops can significantly prolong the survival of allografts at high risk and inhibit corneal neovascularization. However, RAPA-PGLC DDS is far more effective than RAPA eye drops in preventing corneal graft rejection.     

Ex vivo transfer of Smad7 decreases damage to the corneal endothelium after penetrating keratoplasty

PURPOSE: To determine whether transient gene transfer and expression of the intracellular antagonist of transforming growth factor beta (TGF-beta), Smad7, to corneal endothelial cells decreases corneal endothelial cell damage after penetrating keratoplasty in a rabbit model. METHODS: Rabbit corneas were transfected ex vivo with replication-deficient adenoviruses encoding Flagtagged Smad7, Flag-tagged Smad3, or LacZ (termed AdCMV-Smad7, AdCMV-Smad3, AdCMV-LacZ) and then transplanted to normal rabbits. Expression of the exogenous Smads and phosphorylation of endogenous Smad2 in the transplanted corneal endothelium were examined by immunoblotting and immunohistochemistry with anti-Flag or anti-phosphorylated Smad2 antibodies. Cellular density and morphological changes in the corneal endothelium of the transplanted cornea were evaluated by scanning electron microscopy after transplantation of the Smad-transfected corneas. RESULTS: Transplanted AdCMV-Smad7-transfected corneas significantly inhibited the decrease in cellular density and accelerated wound healing at the host-graft junction when compared with transplanted AdCMV-LacZ-transfected corneas. Transplanted AdCMV-Smad3-transfected corneas showed decreased cellular density and delayed wound healing at the host-graft junction. CONCLUSIONS: Ex vivo gene transfer of Smad7 to corneal endothelial cells inhibits the decrease in cellular density and accelerates wound healing after penetrating keratoplasty in rabbits. Thus, modulation of Smad7 expression in corneal endothelial cells may decrease corneal endothelial cell damage after penetrating keratoplasty.     

大鼠角膜碱烧伤模型制备方法的研究

目的:探索相对稳定性强、一致性好的大鼠角膜碱烧伤动物模型。方法:将87只SD大鼠分为角膜缘碱烧伤20s组(A组,34只),角膜缘碱烧伤40s组(B组,23只),角膜中央碱烧伤40s组(C组,30只),用浸润1mol/L氢氧化钠的滤纸片,分别烧灼大鼠角膜缘和角膜中央,术后7d裂隙灯显微镜观察角膜透明度、角膜溃疡及角膜新生血管情况,并记录上述指标。结果:角膜缘碱烧伤(B组)较角膜中央烧伤(C组)溃疡发生率、角膜穿孔率和角膜上皮荧光素钠染色阳性率高,且有统计学差异(P<0.05);角膜缘烧灼时间长组(B组)溃疡发生率及角膜穿孔率高于角膜缘烧灼时间短组(A组),且有统计学差异(P<0.05);烧灼角膜缘和角膜中央(A,B,C组)均能诱导出角膜新生血管。结论:对于研究角膜新生血管的动物模型,以选择3mm圆形滤纸片角膜中央烧伤为佳;对于研究角膜缘干细胞缺乏所致角膜病变的实验,以选择环形滤纸片放置于角膜缘20s为佳。     

诱导供体特异性前房相关免疫偏离对高危角膜移植排斥反应的影响

目的:探讨诱导供体特异性的前房相关免疫偏离(anterior chamber-associated immune deviation,ACAID)对高危角膜移植排斥反应的影响。方法:采用新西兰白兔眼角膜建立碱烧伤眼模型,实验动物随机分为4组,A:正常角膜常规角膜移植组(正常对照组);B:碱烧伤常规角膜移植组(碱烧伤对照组);C:正常角膜诱导ACAID的角膜移植组(正常诱导组)。D:碱烧伤后诱导ACAID的角膜移植组(碱烧伤诱导组)。B,D组进行左眼碱烧伤,烧伤后1mo进行角膜移植。C,D组在角膜移植前2wk于右眼前房注入可溶性抗原以预先诱导供体特异性ACAID。A,B组右眼前房注等量平衡盐溶液。术后记录植片存活时间;对角膜新生血管(corneal neovascularization,CNV)生长情况进行评分;记录移植排斥指数(rejection index,RI);角膜固定、包埋后制作切片行HE染色。结果:A、C组角膜植片长期存活,碱烧伤对照组植片平均存活25.13±0.64d,碱烧伤诱导组角膜植片平均存活时间为38.25±1.28d。与碱烧伤对照组相比,碱烧伤诱导ACAID组角膜植片平均存活时间显著延长,两组植片存活时间的差异具有统计学意义(P=0.00)。结论:诱导供体特异性ACAID可以延长碱烧伤高危眼角膜植片的存活时间。     

Small, overlapping tectonic keratoplasty involving graft-host junction of penetrating keratoplasty

PURPOSE: To report the indications for and postoperative course of small tectonic keratoplasties overlapping (and involving) the graft-host junction of preexisting penetrating keratoplasties. METHODS: A retrospective study of 15 consecutive eyes (15 patients) with small tectonic keratoplasties overlapping the graft-host junction of preexisting penetrating keratoplasties. RESULTS: After tectonic keratoplasty, follow-up times ranged from 5 months to 20 years (mean, 69 months). Clinical indications included sterile corneal ulceration (seven cases), bacterial keratitis (six cases), and fungal keratitis (two cases). In the six cases with bacterial keratitis, five were suture abscesses, with four resulting in wound dehiscence. Ten tectonic grafts were lamellar keratoplasties, and five were penetrating keratoplasties. Postoperative best-corrected visual acuities were unchanged from preoperative levels in every patient. After tectonic grafting, the mean +/- SD change in keratometric astigmatism in the parent penetrating keratoplasty was 1.75 +/- 1.50 diopters. The astigmatism increased in 10 cases, decreased in three, and remained unchanged in two. There was no case of recurrent ulceration or wound dehiscence in or around the tectonic grafts. The surgery did not result in new glaucoma or worsening of preexisting glaucoma. CONCLUSIONS: In the treatment of infectious or ulcerative foci at or near the graft-host junction of penetrating keratoplasties, a small extirpative, tectonic graft over the diseased junction appears to be a safe and effective alternative to either repeating the original penetrating keratoplasty or performing an oversize transplant.