Late corneal ectasia after penetrating and deep anterior lamellar keratoplasty for keratoconus

AIM:To investigate tomographic features of late corneal ectasia after keratoplasty for keratoconus and compare penetrating keratoplasty(PK)and deep anterior lamellar keratoplasty(DALK)in terms of incidence,time of onset and risk factors of corneal ectasia.METHODS:Sixty eyes with PK and 30 eyes with DALK operated between 1999 and 2021 were analyzed.Final Pentacam scans were evaluated together with vision and previous topographies.Main outcome measures were vision,K values,apparent thinning on graft-host cornea and the difference between opposing quadrants in the thinnest point measurements.Anterior segment optic coherence tomography was performed for further evaluation.RESULTS:Mean follow-up was 127.2mo(24–282mo)in PK,and 64.3mo(24–144mo)in DALK.K max was higher in DALK(60.6 vs 56.7 D,P=0.012).Inferior recipient was thinner(595.9μm)in PK than DALK(662.2μm,P=0.021),due to longer follow-up.Overall corneal ectasia rate was 20.0% within 24y.Ectasia rate was the same(6.7%)in DALK 2/30 and in PK 4/60 in 10y and 13.3%in 12y(4/30 and 8/60,respectively).It increased to 23.3%(14/60)in PK over 24y.While ectasia was not seen before 7y in PK,it could be seen in DALK starting from the 5^(th) year.The intervals between keratoplasty and ectasia were 144.5mo in PK and 99mo in DALK.Inferior recipient was significantly thinner in 18 eyes with ectasia(502.7μm)compared to 76 non-ectasia(649.1μm,P=0.000).Inferior graft was thinner(561.0 vs 620.4μm,P=0.006),K max(63.3 vs 56.5 D,P=0.000),and anterior elevation was higher in ectasia(89.1 vs 48.6μm,P=0.002).Accelerated crosslinking was performed on 5 eyes.CONCLUSION:Inferior-superior recipient and inferior graft thinning on tomography,with high K max and anterior elevation emerge as the most reliable criteria for the diagnosis of late ectasia.The incidence of corneal ectasia increases with the time.

In Vivo Confocal Microscopic Observation of Lamellar Corneal Transplantation in the Rabbit Using Xenogenic Acellular Corneal Scaffolds as a Substitute

Background： The limiting factor to corneal transplantation is the availability of donors. Research has suggested that xenogenic acellular corneal scaffolds （XACS） may be a possible alternative to transplantation. This study aimed to investigate the viability of performing lamellar corneal transplantation （LCT） in rabbits using canine XACS. Methods： Fresh dog corneas were decellularized by serial digestion, and LCT was performed on rabbit eyes using xenogeneic decellularized corneal matrix. Cellular and morphological changes were observed by slit-lamp, light, and scanning electron microscopy at 7, 30 and 90 days postoperatively, lmmunocytochemical staining for specific markers such as keratin 3, vimentin and MUC5AC, was used to identify cells in the graft. Results： Decellularized xenogenic corneal matrix remained transparent for about l-month after LCT. The recipient cells were able to survive and proliferate into the grafts. Three months after transplantation, grafts had merged with host tissue, and graft epithelialization and vascularization had occurred. Corneal nerve fibers were able to grow into the graft in rabbits transplanted with XACS. Conclusions： Xenogenic acellular corneal scaffolds can maintain the transparency of corneal grafts about 1-month and permit growth of cells and nerve fibers, and is, therefore, a potential substitute or carrier for a replacement cornea.

Comparison of long-term results after manual and femtosecond assisted corneal trephination in deep anterior lamellar keratoplasty for keratoconus

AIM: To compare long-term postoperative outcomes of manual and femtosecond assisted corneal trephination in deep anterior lamellar keratoplasty(FS-DALK) for keratoconus.METHODS: In the retrospective study, 17 consecutive eyes that underwent vertical side cut incision FS-DALK and 22 eyes that underwent trephine incision DALK were collected over a 2-year period. Main measurements included postoperative uncorrected-visual acuity(UCVA), corrected distance visual acuity(CDVA), refractive sphere and cylinder, manifest refraction spherical equivalent(MRSE), flat and steep corneal keratometry(K1 and K2), endothelial cell density(ECD), and time of epithelium healing and suture removal.RESULTS: Groups were comparable for diagnosis and preoperative visual acuity. Follow-up averaged 23 mo(range, 12-36 mo). At 12 mo, the mean UCVA was better in the manual-DALK group(P=0.039), and the refractive sphere was lower in the FS-DALK group(P=0.040). MRSE between groups differed at 1, 6, and 12 mo postoperatively(P=0.047, 0.025, 0.042, respectively). Mean CDVA, cylinder, K1, K2,corneal astigmatism, ECD, and time of epithelium healing were similar between groups. Stability of MRSE, ECD, and K1 returned sooner after FS-DALK. Initial loosened suture removal time was earlier in the manual-DALK group(P=0.042) while complete suture removal time was similar(P=0.122).CONCLUSION: Manual and femtosecond assisted corneal trephination in DALK are options for advanced keratoconus. FS-DALK do not result in improved visual acuity but it is more stable during the follow-up period. FSDALK in the present form show limited benefit, so surgical design and parameters still need to be optimized and explored.

Central corneal epithelium self-healing after ring-shaped glycerin-cryopreserved lamellar keratoplasty in Terrien marginal degeneration

Dear Sir, I am Dr Yan-Long Bi, from the Department of Ophthalmology, Tongji University Affiliated to Tongji University School of Medicine, Shanghai, China. I write to present a case report of total limbal stem cells deficiency after treatment with ring-shaped lamellar keratoplasty secondary to Terrien marginal degeneration. During 3 years

Preoperative evaluation and outcome of corneal transplantation for limbal dermoids：aten-yearfollow-up study

AIM： To summarize preoperative evaluation and outcome of corneal transplantation for limbal dermoids for ten years.METHODS： Eighty-five patients diagnosed with limbal dermoids and treated with corneal transplantation were analyzed retrospectively. All patients were further divided into two groups according to absence or presence of neovascularization surrounding the dermoids in the corneal stroma. Eighty-two eyes were treated with tumor excision combined with partial lamellar sclerokeratoplasty, and the other three eyes were performed by penetrating keratoplasty. The size and location of the tumor, the associated ocular and systemic anomalies, the depth of the corneal penetration of tumor tissues, the preoperative and postoperative best-corrected visual acuity （BCVA）, graft survival and cosmetic outcome, and surgical complications were recorded respectively.RESULTS： The average age at surgery was 5.3y （range, 3mo-36y）. The mean size of dermoids was 6.1±1.6 mm. The 43.5% of eyes （37/85） were present with hair at the surface of the dermoid and 72.9% of dermoids were located inferotemporal of the eye. Amplyopia was present in 34.1% of patients （29/85） and 9.4% of patients （8/85） had lipodermoids. Eighteen patients suffered from Goldenhar’s syndrome with an accessory ear. The 75% of patients in group 1 had involvement of the corneal deep stroma down to Descemet’s membrane without involving it, but 71.4% of patients had Descemet’s membrane involvement in group 2. Preoperative BCVA ranged from counting fingers to 20/20. Postoperatively 81.1% had a BCVA of 20/800 or better. There was no significant difference between the post-surgical BCVA of the two groups （t=1.584, P〉0.05）. The grafts of 70.5% patients were present as 1＋ opacity, 21.1% as 2＋ opacity, 8.2% as 3＋ opacity and none as 4＋ opacity. Surgical complications included graft rejection, microperforation, prolonged reepithelialization, steroid glaucoma, interface neovascularization, and interface hemorrhage.CONCLUSION： The dermoids with neovascularization surrounding them in the corneal stroma invaded deeper tissues in the cornea than those with no neovascularization surrounding them in the corneal stroma. Therefore, surgeons should take care to avoid corneal perforation during the corneal transplantation operation. The majority of patients markedly improved their cosmetic appearance after surgery.

Cryopreserved limbal lamellar keratoplasty for peripheral corneal and limbal reconstruction

This study aimed to evaluate the outcomes and described the recovery process of cryopreserved limbal lamellar keratoplasty（CLLK） for peripheral corneal and limbal diseases. Thirteen eyes of 12 patients with a mean age of 41±23.9 y were included. The average follow-up was 12.1±5.6 mo. Stable ocular surface was achieved in all eyes at last follow-up. Epithelialization originated from both recipient and graft in 9 eyes. We conclude that CLLK compensates for the shortage of donor corneas and cryopreserved limbal grafts provide epithelialization sources in ocular surface reconstruction.

Phacoemulsification in eyes with corneal opacities after deep anterior lamellar keratoplasty

To evaluate the maneuverability and efficacy of phacoemulsification and intraocular lens(IOL) implantation in eyes with corneal opacities after deep anterior lamellar keratoplasty(DALK), twelve eyes of 12 patients with mild to moderate corneal opacities after DALK and coexisting cataracts were analyzed retrospectively. Phacoemulsification and IOL implantation assisted with anterior capsule staining, as well as non-invasive optical fiber illumination, were performed on all eyes. No intraoperative or postoperative complications were noted. Mean corrected distance visual acuity(logMAR) improved from 1.24±0.17 to 0.73±0.22. Post-phaco intraocular pressure was maintained between 13 to 20 mm Hg in all cases throughout the follow-up period. Mean endothelial cell density decreased from 2258.42±205.94 to 1906.25±174.23 cells/mm2. Phacoemulsification and IOL implantation are safe and valid in eyes with mild to moderate corneal opacities after DALK and coexisting cataracts when assisted with anterior capsule staining and non-invasive optical fiber illumination.

A 60-Year-Male Post Corneal Transplantation with Acute Pneumonia

Pneumonia is a common complication in organ transplantation patients. Multiple respiratory pathogens such as bacteria, viruses and fungi are potentially coexisted. A 60-year-old male with left eye post corneal transplantation developed acute severe pneumonia caused by Pneumocystis jiroveci (PJP) coinfection with Nocardia spp. and Cytomegalovirus (CMV). He was hospitalized due to acute respiratory failure. Chest radiographs and chest Computed Tomography (CT) revealed extensive ground-glass opacities. PJP was diagnosed from Bronchoalveolar Lavage Fluid (BALF). The pneumonia was persistent despite of receiving intravenous cotrimoxazole. Tracheal aspirate showed faint gram-positive filamentous beaded branching organisms. Consequently Nocardia spp. was proven. Intravenous cotrimoxazole was continued and intravenous imipenem was added. After a course of dual antibiotics, pneumonia was gradually improved. A week after, he developed the worsened acute respiratory failure. The bronchoscopy was performed. The new pathogens were not detected from BALF microbiology. The BALF cytology was unremarkable. PJP was detected by Polymerase Chain Reaction (PCR) from BALF. CMV antigenemia was detected from BALF and blood. Intravenous ganciclovir was given. This report describes PJP coinfected with Nocardia spp. and CMV in post corneal transplantation patient suffering from severe pneumonia. Multiple respiratory pathogens are common among transplantation patients representing host immunosuppression and inadequate antimicorbial prophylaxis.

Clinical Analysis of 30 Cases of Deep Lamellar Keratoplasty for the Treatment of Corneal Disease

purpose： to analyze clinical therapeutic effect of deep lamellar keratoplasty on treatment of corneal disease. Method： select 30 cases of corneal disease patients with a total of sick eyes, from 2012 January to 2013 January; all patients underwent deep lamellar keratoplasty, then observe and analyze visual acuity, corneal and occurrence of complications, to comprehensively assess the clinical therapeutic effect. Result： after receiving treatment of deep lamellar keratoplasty, of the 30 patients and 40 eyes, 31 corneal grafts are transparent; 9 corneal grafts are translucent; postoperative visual acuity： I0 eyes are 0.01-0.04; 13 eyes are 0.05~0.1; 14 eyes are 0.1-0.4; 3 eyes are above 0.5; 10 eyes have descemet micro-perforation or small perforation; 7 eyes have complications; these conditions are all controlled after active treatment. Conclusion： for patients with corneal disease, deep lamellar keratoplasty can not only achieve the similar transparency and visual rehabilitation as penetrating keratoplasty, but also reduce the incidence of adverse reactions and reject reaction after operation, to achieve the purpose of treatment and vision improvement; it has significant clinical effect, and greatly improve the quality of patients＇ life, so it is worthy of clinical application.

Graft rejection after deep anterior lamellar keratoplasty in fellow eye in macular corneal dystrophy: a case report

Because of the low incidence of immunological rejection,deep anterior lamellar keratoplasty(DALK)is currently the preferred treatment for macular corneal dystrophy(MCD).However,there were few reports about whether the consistent results were obtained when performing DALK in both eyes for MCD,especially when the corneal grafts were taken from different donors.Also,there were few reports about whether the stromal graft rejection occurred typically in both eyes in MCD with DALK.This case may represent the first report of an unusual and misleading manifestation of stromal graft rejection after uneventful DALK with big bubble technique in the fellow eye in MCD.A 32-year-old healthy man with MCD underwent bilateral uneventful DALK with a big bubble technique in the left eye in January and the right eye in July,the corneal grafts were taken from different donors.There was an atypical allograft rejection that occurred in the right eye and none in the left eye;although a timely diagnosis of graft rejection revealed following aqueous determination,it could not be reversed and underwent PK finally.The purpose of this case report is to illustrate the identification of atypical allograft rejection after DALK in the fellow eye,the significance of aqueous detection in the diagnosis of graft rejection,the choosing of grafts,and the timing of bilateral corneal transplantation in patients with MCD.

Donor cornea quality used for penetrating keratoplasty vs deep anterior lamellar keratoplasty

Deep anterior lamellar keratoplasty(DALK) has recently been introduced as an alternative procedure to penetrating keratoplasty(PK) for corneal pathologies not affecting the corneal endothelium. DALK does not rely on donor endothelium and requires less rigid criteria for donor corneal tissue quality. Therefore, DALK makes it possible to use donor corneas deemed unsuitable for PK. Furthermore, lamellar keratoplasty allows acellular corneal tissue to be transplanted. As a result, long-term preservation techniques are being revisited to increase the availability of donor corneas and subsequently alleviate constraints of availability, cost, storage, and transportation in many countries. The recent alterations in corneal transplantation techniques and hence the type of donor cornea tissues used for each technique, may require corneal surgeons and eye banks to reevaluate their selection criteria. The purpose of this systematic review is to present an updated analysis on the type and quality of donor corneas used for PK and DALK, assess the influence of donor and eye bank factors on the quality of donor corneas, and determine whether any of these donor factors affect clinical outcomes, complications, and graft survivals.

Fresh Amniotic Membrane Transplantation Combined Lamellar Keratoplasty for Patients with Recurrent Mooren's Ulcer

Purpose: To investigate the possibility of amniotic membrane as an immunologicalinsulating band to reduce the recurrent frequency of Mooren's ulcer.Methods: Twelve cases(12 eyes)with recurrent Mooren's Ulcer were observed. Amongthem, 4 cases(4 eyes)were male and 8 cases(8 eyes) female, ranging in age between 26and 51 years[mean(41 ± 3)years]. Three eyes recurred once, 5 eyes twice, and 4 eyesthree before. Eleven of 12 cases (11/12 eyes)with frequently recurrent Mooren's ulcerunderwent lamellar keratoplasty combined amniotic membrane transplantation(AMT).One patient who had entire corneal ulceration accepted AMT alone.Results: Follow-up time is 12 to 29 months, [mean (23 ± 6) months]. Before AMT, therecurrent frequency of Mooren's Ulcer of all cases after corneal surgery was 1 ～ 7 months[mean(3 ± 2)months]. Nine of 12 eyes with lamellar keratoplasty combined AMT did notrecur within the observation period; 2 eyes recurred 11 months after the surgery. Threemonths postoperatively, neovascularization was observed, which made it nearly impossibleto decipher between amniotic membrane and its nearby conjunctiva, only at the junctionof the transplant can some trails be observed. One case with entire AMT alone showedgraft resolution and neovascularization in 1 month.Conclusion:AMT combined with lamellar keratoplasty and lesion excision may delayrecurrence of Mooren's Ulcer, reduce its recurrent frequency. Besides the effects ofdecreasing inflammation, it may have immunological insulating function as well. Thisconclusion should be proven by further clinical comparative study of much moresamples.

Comparison of contrast sensitivity and visual acuity between deep anterior lamellar keratoplasty and penetrating keratoplasty in patients with keratoconus

AIM: To evaluate postoperative visual acuity and contrast sensitivity results following deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in patients with keratoconus (KC). METHODS: All the patients’ records with KC who had PK or DALK surgery between May 2010 and May 2011 were retrospectively reviewed. Sixty patients who underwent successful corneal transplantation for KC: 30 eyes underwent DALK and 30 eyes underwent PK were included in this study. Preoperative and postoperative mean logarithm of the minimum angle of resolution (logMAR) uncorrected visual acuity (UCVA), logMAR best spectacle-corrected visual acuity (BSCVA) and intraocular pressure (IOP) were evaluated. Contrast sensitivity tests (CS) were done preoperative and 2 months after all sutures had removed. All surgeries were performed under regional anesthesia (retrobulbar anesthesia) by 1 surgeon (B.K.) who was experienced in penetrating and lamellar keratoplasty techniques. RESULTS: The mean age of the DALK group was 29.67±4.95 (range 18-40) years and the PK group was 28.7±3.53 (range 18-39) years. Preoperatively there was no significant difference in the logMAR UCVA, logMAR BSCVA and IOP between the DALK (1.281±0.56; 0.97±0.85; 12.07±2.12mmHg) and PK (1.34±0.21; 0.98±0.21; 13±2.12mmHg) groups. One-year after surgery there was no significant difference in the mean logMAR UCVA and IOP between the DALK (0.46±0.37; 11.73±2.1mmHg) and PK (0.38±0.21; 12±2.12mmHg) groups. The mean contrast sensitivity was evaluated by CC-100 Topcon LCD at 1.5, 2.52, 4.23, 7.10 and 11.91 cycles per degree (cs/deg) spatial frequencies before and 2 months after the all sutures had removed. CONCLUSION: All patients with keratoconus in both DALK and PK groups performed good visual function postoperatively. The mean contrast sensitivity increased considerably at all spatial frequencies compared with preoperative levels in the DALK and PK groups. The mean post-operative evaluation of contrast sensitivity measurements was not significantly different between the two groups.

Transplantation of tissue-engineered human corneal epithelium in limbal stem cell deficiency rabbit models

AIM: To evaluate the biological functions of tissue-engineered human corneal epithelium (TE-HCEP) by corneal transplantation in limbal stem cell deficiency (LSCD) rabbit models. METHODS: TE-HCEPs were reconstructed with DiI-labeled untransfected HCEP cells and denuded amniotic membrane (dAM) in air-liquid interface culture, and their morphology and structure were characterized by hematoxylin-eosin (HE) staining of paraffin-sections, immunohistochemistry and electron microscopy. LSCD models were established by mechanical and alcohol treatment of the left eyes of New Zealand white rabbits, and their eyes were transplanted with TE-HCEPs with dAM surface outside by lamellar keratoplasty (LKP). Corneal transparency, neovascularization, thickness, and epithelial integrality of both traumatic and post transplantation eyes were checked once a week by slit-lamp corneal microscopy, a corneal pachymeter, and periodic acid-Schiff (PAS) staining. At day 120 post surgery, the rabbits in each group were sacrificed and their corneas were examined by DiI label observation, HE staining, immunohistochemistry and electron microscopy. RESULTS: After cultured for 5 days on dAM, HCEP cells, maintaining keratin 3 expression, reconstructed a 6-7 layer TE-HCEP with normal morphology and structure. The traumatic rabbit corneas, entirely opaque, conjunctivalized and with invaded blood vessels, were used as LSCD models for TE-HCEP transplantation. After transplantation, obvious edema was not found in TE-HCEP-transplanted corneas which became more and more transparent, the invaded blood vessels reduced gradually throughout the monitoring period. The corneas decreased to normal thickness on day 25, while those of dAM eyes were over 575 mu m in thickness during the monitoring period. A 45 layer of epithelium consisting of TE-HCEP originated cells attached tightly to the anterior surface of stroma was reconstructed 120 days after TE-HCEP transplantation, which was similar to the normal control eye in morphology and structure. In contrast, intense corneal edema, turbid, invaded blood vessels were found in dAM eyes, and no multilayer epithelium was found but only a few scattered conjunctiva-like cells appeared. CONCLUSION: The TE-HCEP, with similar morphology and structure to those of innate HCEP, could reconstruct a multilayer corneal epithelium with normal functions in restoring corneal transparency and thickness of LSCD rabbits after transplantation. It may be a promising HCEP equivalent for clinical therapy of corneal epithelial disorders.

The lived experiences of patients undergoing acellular porcine corneal stroma transplantation

To explore the lived experiences of patients undergoing acellular porcine corneal stroma（APCS）transplantation,a descriptive,qualitative design was performed.A purposive sample of 13 patients who underwent APCS transplantation to treat progressive infectious keratitis were enrolled in the semi-structured,open-ended interviews.The taped and transcribed interviews were analyzed using a thematic analysis approach.Alterations in the transparency of APCS grafts were accompanied by a gradual improved visual acuity（before surgery：1.38±0.91 logMAR;3mo postoperatively ：0.40±0.24 logMAR, respectively）.Accordingly,in terms of lived experiences,the patients generally reported＂negative＂experiences before the operation and during the early postoperative period,but this was greatly improved 3mo after surgery.Four main themes were derived：anxiety and fear,stigma,lifestyle change,and gratitude and insights. Conclusively,health care professionals should provide holistic care for patients,proactively promoting patients’physical and mental health.

Assessments of tear meniscus height, tear film thickness, and corneal epithelial thickness after deep anterior lamellar keratoplasty

Objective： To assess the lower tear meniscus height（LTMH）, central tear film thickness（CTFT）, and central corneal epithelial thickness（CCET） after deep anterior lamellar keratoplasty（DALK）. Methods： This was a retrospective cross-sectional study of 20 patients who had DALK in one eye over a three-month period. LTMH, CTFT, and CCET of the operated eyes and the unoperated fellow eyes were measured using high-definition optical coherence tomography（HD-OCT）. Correlations between three OCT assessments and age, time following surgery, graft size, bed size, and the number of residual sutures were analyzed. Results： Compared to patients with keratoconus, patients with other corneal conditions had significantly higher CCET in the fellow eye（P=0.024）. For all patients, CCET in the operated eye was significantly negatively correlated with the number of residual sutures（R=-0.579, P=0.008）, and was significantly positively correlated with time following surgery（R=0.636, P=0.003）. In the fellow eye, a significant positive correlation was found between age and CCET（R=0.551, P=0.012）, and a significant negative correlation between age and CTFT（R=-0.491, P=0.028）. LTMH was found to be significantly correlated between operated and fellow eyes（R=0.554, P=0.011）. There was no significant correlation between LTMH and age, bed/graft size, time following surgery, or residual sutures（all possible correlations, P0.05）. Conclusions： Patients with keratoconus tend to have a thinner central corneal epithelium. Corneal epithelium keeps regenerating over time after DALK. DALK did not induce a significant change in tear volume compared with the fellow eye. Postoperative tear function might depend on an individual＇s general condition, rather than on age, gender, bed/graft size, time following surgery, or residual sutures.

Small-diameter acellular porcine corneal stroma for peripheral corneal ulceration treatment

AIM:To evaluate the clinical efficacy of small-diameter acellular porcine corneal stroma(SAPS)for the treatment of peripheral corneal ulceration(PCU).METHODS:This retrospective clinical study included 18 patients(18 eyes)with PCU between April 2018 and December 2020.All patients had PCU and underwent lamellar keratoplasty with SAPS.Observation indicators included preoperative and postoperative best-corrected visual acuity(BCVA)and transparency of SAPS.The infection control rate in the surgical eye-lesion area was also calculated.RESULTS:Eighteen patients underwent lamellar keratoplasty with SAPS to treat PCU.None of the patients experienced rejection after 6mo(18/18)and 12mo(16/16)of follow-up.The BCVA(0.47±0.30)at the 6mo followup after operation was significantly improved compared with the baseline(0.99±0.80),and the difference was statistically significant(Z=-3.415,P<0.05).The BCVA at the 12mo follow-up after operation was not statistically significant compared to the 6mo(Z=0,P=1).With time,the SAPS graft gradually became transparent.At the 6mo(18/18)and 12mo(16/16)follow-up,none of the patients had recurrent corneal infection.CONCLUSION:SAPS is clinically effective in the treatment of PCU,improving the patient’s BCVA and reducing the incidence of rejection after keratoplasty.

Effects of corneal thickness distribution and apex position on postoperative refractive status after full-bed deep anterior lamellar keratoplasty

Objective： To investigate the effects of corneal thickness distribution and apex position on postoperative refractive status after full-bed deep anterior lamellar keratoplasty （FBDALK）. Methods： This is a retrospective analysis of patients who were diagnosed with advanced keratoconus between 2011 and 2014 in our hospital. The base of the cone in all patients did not exceed the central cornea at a 6-mm range. The FBDALK was performed by a same surgeon. All patients had a complete corneal suture removal and the follow-up records were intact. Patients who had graft-bed misalignment or who were complicated with a cataract or glaucoma were excluded. Uncorrected visual acuity （UCVA）, best spectacle corrected visual acuity （BSCVA）, and Pentacam examination data were recorded at two years postoperatively. The recorded data included the superior-inferior （S-I） and nasal-temporal （N-T） corneal thickness differences in 2, 4, 6, and 8 mm diameter concentric circles with the corneal apex as the center （S-I2 mm, S-14 mm, S-I6mm,, S-I8mm, N-T2mm, N-T4 mm, N-T6 mm, and N-T8 mm）, the linear, X-axis, and Y-axis distance between the corneal pupillary center and the cornea apex, total corneal astigmatism at a zone of 3 mm diameter from the corneal apex （TA3 mm）, the astigmatic vector values J0 and J4s, and the corneal total higher-order aberration for 3 and 6 mm pupil diameters （HOA3 mm and HOA6mm）. Statistical analysis was performed by SPSS 15.0. Results： A total of 47 eyes of 46 patients met the criteria and were included in this study. The mean follow-up time was （28±7） months. The mean UCVA was 0.45±0.23 （IogMAR） （MAR： minimum angle of resolution） and the mean BSCVA was 0.19±0.15 （IogMAR）, which were all sig- nificantly positively correlated with postoperative TA3 mm and HOA3 turn. The mean S-I corneal thickness differences were （44.62±37.74） IJm, and the mean N-T was （38.57±32.29） pm. S-12 mm was significantly positively correlated with J0 （r=0.31）, J45 （r=0.42）, HOA3 mm （r=0.37）, and HOA6 mm （r=0.48）. S-14 mm and S-Is mm were significantly positively corre- lated with HOA3 mm （t=0.30, t=0.40） and HOA6 mm （r=0.46, r=0.35）. The X-axis distance between corneal pupillary center and corneal apex was significantly positively correlated with J45 （r=0.29）. Conclusions： In patients with ad- vanced keratoconus after FBDALK, the unevenly distributed thickness at corneal pupillary area and the misalignment of corneal apex and pupillary center might cause significant regular and irregular astigmatism, which affected the postoperative visual quality.

Corneal transplantation outcomes after the extrusion of an intrastromal keratoprosthesis:a pilot study

This short report includes 5 eyes of 5 patients(mean age 63.2±12 years)who underwent a tectonic keratoplasty[deep anterior lamellar keratoplasty(DALK)or penetrating keratoplasty(PK)]in order to rehabilitate the eye after the extrusion of the non-perforating keratoprosthesis(Kpro)KeraKlear(KeraMed,USA).The non-perforating Kpro was extruded after a mean period of 21.4±21.8 months due to melting.In two cases,the keratoplasty was performed the same day of the non-perforating Kpro removal due to a severe melting,while in the other three cases it was performed one to 3 months later.Two eyes received a DALK,but in 3 eyes a macroscopic Descemet membrane perforation forced the conversion into a PK.The mean follow-up period after the keratoplasty was 16.8±6.6 months.No cases of rejection were recorded.All the 5 eyes achieved“anatomical success”(transparent graft,with no signs of infection or inflammation).Two eyes showed limited“functional success”because the achievement of the best visual potential was prevented by the development of glaucomatous optic atrophy during the follow-up period.In conclusion,this short report presents an unexpected success of a keratoplasty performed with a tectonic purpose after the extrusion of the non-perforating Kpro because the corneal graft remained transparent,without neovascularization or scarring during the follow-up period.This initial evidence shows some encouraging results regarding graft survival rate and the achievement of a useful visual rehabilitation with keratoplasty after a nonperforating Kpro failure instead of repeating the Kpro implantation.

Mesenchymal stem cells: Potential role in corneal wound repair and transplantation

Corneal diseases are a major cause of blindness in the world. Although great progress has been achieved in the treatment of corneal diseases, wound healing after severe corneal damage and immunosuppressive therapy after corneal transplantation remain prob-lematic. Mesenchymal stem cells(MSCs) derived from bone marrow or other adult tissues can differentiate into various types of mesenchymal lineages, such as osteocytes, adipocytes, and chondrocytes, both in vivo and in vitro. These cells can further differentiate into specific cell types under specific conditions. MSCs migrate to injury sites and promote wound healing by secreting anti-inflammatory and growth factors. In ad-dition, MSCs interact with innate and acquired immune cells and modulate the immune response through their powerful paracrine function. Over the last decade, MSCs have drawn considerable attention because of their beneficial properties and promising therapeutic prospective. Furthermore, MSCs have been applied to various studies related to wound healing, autoim-mune diseases, and organ transplantation. This review discusses the potential functions of MSCs in protecting corneal tissue and their possible mechanisms in corneal wound healing and corneal transplantation.