Corneal stromal changes following reconstruction by ex vivo expanded limbal epithelial cells in rabbits with total limbal stem cell deficiency.

AIM: To study corneal stromal changes and the presence of myofibroblasts after transplantation of ex vivo expanded limbal epithelium. METHODS: A state of limbal deficiency was induced in 16 rabbits. After transplantation with autologous ex vivo expanded limbal epithelium on amniotic membrane (AM), their clinical outcomes were classified as success, partial success or failure according to surface smoothness, stromal clarity, and vascularisation. Clinical outcomes were correlated with phenotypic outcomes of corneal, conjunctival, or mixed epithelium, defined by expression of K3 keratin or MUC5AC. Immunostaining was performed with antibodies against collagen IV, fibronectin, and alpha-smooth muscle actin (alpha-SMA) to assess stromal wound remodelling. RESULTS: Rabbits were sacrificed after a mean follow up of 10 (SD 3.3) months. Collagen IV, expressed in the basement membrane of all three groups, was found in the stroma of the partial success, but not in that of the success or the failure. Fibronectin was absent in the success and the failure, but expressed in the stroma of the partial success. Alpha-SMA was expressed in superficial stroma of the partial success, but suppressed in areas with AM remnants. CONCLUSION: Restoration of a clear and transparent cornea is associated with a normal corneal epithelium and complete wound remodelling. In contrast, wound healing remains active and incomplete in conjunctivalised corneas, which remain opaque with myofibroblasts.

Analysis of variation in success rates in conjunctival autografting for primary and recurrent pterygium.

AIMS: To evaluate the success rates of conjunctival autografting for primary and recurrent pterygium performed in a tertiary ophthalmic centre. METHODS: The outcome of 139 cases with primary pterygia and 64 cases with recurrent pterygia who underwent excision with conjunctival autografting was retrospectively reviewed. Outcome was evaluated in terms of recurrence of pterygia onto the cornea. The recurrence rates were determined using Weibull survival functions, in a mixture model that included a component allowing for cure. The suitability of this model was verified using Turnbull's non-parametric method for interval censored data (1974). Estimated recurrence free probabilities were based on the fitted Weibull survival curves. RESULTS: Mean follow up was 8.4 months in the primary group, and 9.5 months for the recurrent group. 29 out of 139 cases of primary pterygia recurred (20.8%) while 20 out of 64 cases in the recurrent group (31.2%) recurred. Recurrence rates varied widely among surgeons, ranging from 5% to 82%. Recurrence rates were inversely related to previous experience in performing conjunctival grafting. The recurrence free probability was 84% at 3 months, 73% at 1 year for primary pterygia, and 80% at 3 months, 67% at 1 year for recurrent pterygia. There was no statistical difference in recurrence rates between primary and recurrent groups (p= 0.80). CONCLUSION: The success of conjunctival autografting for pterygium in this series varies widely, and may be related to a significant learning curve or differing surgical techniques for this procedure. This may account for the wide variation in reported success of this procedure in the ophthalmic literature.

Correlation of long term phenotypic and clinical outcomes following limbal epithelial transplantation cultivated on amniotic membrane in rabbits.

AIM: To determine the epithelial phenotype in rabbits with total limbal stem cell deficiency (LSCD) after reconstruction with autologous limbal epithelial stem cells ex vivo expanded on rabbit amniotic membrane (AM). METHODS: Left eyes of 52 rabbits were rendered total LSCD, verified by impression cytology. The fibrovascular pannus of each cornea was removed. Group I (n = 10) received rabbit AM transplantation alone, while groups II-IV (n = 42) underwent transplantation of LSC cultured on rabbit AM (LSC-AM) from a small limbal biopsy taken from the right eye. Clinical outcome was graded as "success," "partial success," or "failure" depending on the corneal smoothness and avascularity. Epithelial phenotype was determined by immunostaining and graded as "corneal (K)," "conjunctival (J)," or "mixed (M)" depending on expression of K3 and Muc5AC. RESULTS: After 1 year follow up, group I showed 100% failure and groups II-IV showed 26% success (p<0.001). Clinical failure correlated with J phenotype p = 0.001), while clinical success correlated with K phenotype p = 0.01). When the phenotypic outcome was used for comparison, J phenotype was significantly high in group I (p = 0.003), while K phenotype was significantly high in groups II-IV (p<0.05). CONCLUSION: There is a strong correlation between clinical success and resultant corneal epithelial phenotype. Ex vivo expanded LSC can successfully reconstruct corneal surfaces with unilateral total LSCD.

Postoperative inflammation: extracapsular cataract extraction versus phacoemulsification.

PURPOSE: To quantitatively compare postoperative inflammation after extracapsular cataract extraction (ECCE) with that after phacoemulsification in an Asian population. SETTING: Singapore National Eye Center, Singapore. METHODS: In this prospective, randomized, double-masked clinical trial, patients having cataract surgery were randomized to receive ECCE (n = 16) or phacoemulsification (n = 18). Diabetics were excluded. Two surgeons performed both types of surgery and implanted a 6.0 mm optic intraocular lens. Inflammation was assessed qualitatively by slitlamp grading of cells and flare and quantitatively using the Kowa flare meter. One independent postoperative investigator performed the slitlamp examination and laser flare meter readings. RESULTS: The ECCE and phacoemulsification groups were comparable (P > .05) in age, sex, ethnicity, and preoperative flare levels. The combined slitlamp inflammatory scores (anterior chamber cells and flare) and mean laser flare meter readings showed the ECCE group had significantly higher mean flare measurements than the phacoemulsification group at days 4 (P = .0012), 8 (P = .0013), 15 (P = .0013), 30 (P = .0004), and 60 (P = .0164). Flare levels in the ECCE group returned to preoperative values by the second month; the phacoemulsification group achieved preoperative levels by 1 month. The clinical inflammatory assessment score correlated closely to the flare level readings. CONCLUSION: Phacoemulsification induced less inflammation than ECCE, with the difference most marked in the first month after surgery.

Recurrent corneal erosion after laser in situ keratomileusis.

PURPOSE: To describe how laser-assisted in situ keratomileusis (LASIK) may induce recurrent corneal erosion (RCE) syndrome and the preventive measures for avoiding this complication. METHODS. A case series was used. RESULTS: We report the development of RCE syndrome in eight eyes of six patients after LASIK. In five cases, the RCE was triggered by epithelial trauma at the time of the LASIK procedure, as evidenced by the observation of RCE occurring at the same site as the initial epithelial disturbance. In case 6, RCE occurred with undiagnosed basement membrane dystrophy. The patients responded to treatment with ocular lubricants with one patient undergoing penetrating keratoplasty for RCE after LASIK. CONCLUSION: LASIK can induce or precipitate RCE, and RCE should perhaps be included as a potential complication in the informed consent process. It is important to minimize epithelial damage to prevent RCE after LASIK, and measures to reduce this include adequate irrigation of the corneal surface immediately before the microkeratome pass and careful attention to flap epithelium during flap replacement. Cases in which loose epithelium is noted after LASIK should be identified as potential RCE cases, and extra care should be taken for subsequent enhancement procedures or LASIK of the second eye.

Amniotic membrane transplantation in entropion surgery.

PURPOSE: To evaluate the role of amniotic membrane transplantation in the management of cicatricial eyelid entropion. DESIGN: Prospective, noncomparative interventional case series. PARTICIPANTS: Eighteen consecutive patients with cicatricial entropion. METHODS: A gray line lid split procedure with vertical anterior lamella repositioning was performed on 25 eyelids (upper or lower) of 18 patients with moderate to severe cicatricial entropion. Preserved human amniotic membrane (AM) was used to cover the bare tarsus up to the lid margin and secured with running 7-0 Vicryl. Impression cytology of the AM was performed at various stages postoperatively to study the epithelialization process. MAIN OUTCOME MEASURES: (1) Reepithelialization of bare tarsus, (2) extent of tarsal shrinkage, (3) recurrence of entropion. RESULTS: All the AM grafts took well. The most common complication was hemorrhage below the graft, which occurred in six cases. Complete success with no lashes touching the globe was achieved in 22 of 25 (88%) lids after a minimum follow-up of 12.0 months. The mean follow-up was 17.8 months. Two cases (qualified success) had recurrent trichiasis treated successfully with electrolysis. One case with severe trachomatous upper lid entropion recurred 14 months after surgery. The AM accelerated the epithelialization of bare tarsus; this was demonstrated by lack of fluorescein staining and reversion to skin color within 2 to 3 weeks. However, AM could not prevent tarsal shrinkage. Impression cytology demonstrated that features of conjunctival epithelium were present for the first postoperative month, but this was gradually replaced by squamous metaplasia, with keratinization appearing as early as 3 weeks postoperatively. CONCLUSIONS: The use of AM in a lid split procedure for correction of cicatricial entropion helps the bare tarsus epithelialize rapidly and improves the initial cosmetic result of surgery.