Sayan Basu

Clinical outcomes of xeno-free autologous cultivated limbal epithelial transplantation: a 10-year study

Purpose Ocular burns can damage the corneal epithelial stem cells located at the limbus. This study evaluated the efficacy of xeno-free autologous cell-based treatment of limbal stem cell deficiency. Methods This retrospective study included 200 patients, above 8 years of age, with clinically diagnosed unilateral total limbal stem cell deficiency due to ocular surface burns treated between 2001 and 2010. A small limbal biopsy was obtained from the unaffected eye. The limbal epithelial cells were expanded ex vivo on human amniotic membrane for 10–14 days using a xeno-free explant culture system. The resulting cultured epithelial monolayer and amniotic membrane substrate were transplanted on to the patients affected eye. Postoperative corneal surface stability, visual improvement and complications were objectively analysed. Results A completely epithelised, avascular and clinically stable corneal surface was seen in 142 of 200 (71%) eyes at a mean follow-up of 3±1.6 (range: 1–7.6) years. A two-line improvement in visual acuity, without further surgical intervention, was seen in 60.5% of eyes. All donor eyes remained healthy. Conclusions Autologous cultivated limbal epithelial transplantation using a xeno-free explant culture technique was effective in long-term restoration of corneal epithelial stability and improvement of vision in eyes with ocular surface burns.

Simple limbal epithelial transplantation (SLET): a novel surgical technique for the treatment of unilateral limbal stem cell deficiency

This study describes a novel surgical technique of limbal transplantation, which combines the benefits of existing techniques while avoiding their difficulties. Six patients with unilateral and total limbal stem cell deficiency following ocular surface burns underwent a single-stage procedure. A 2×2 mm strip of donor limbal tissue was obtained from the healthy eye and divided into eight to ten small pieces. After surgical preparation of the recipient ocular surface, these tiny limbal transplants were distributed evenly over an amniotic membrane placed on the cornea. After surgery, a completely epithelialised, avascular and stable corneal surface was seen in all recipient eyes by 6 weeks, and this was maintained at a mean±SD follow-up of 9.2±1.9 months. Visual acuity improved from worse than 20/200 in all recipient eyes before surgery to 20/60 or better in four (66.6%) eyes, while none of the donor eyes developed any complications. This technique requires less donor tissue than previously used for conventional autografting and does not need a specialist laboratory for cell expansion. Although long-term results are awaited, this simple limbal epithelial transplantation promises to be an easy and effective technique for treating unilateral limbal stem cell deficiency following ocular burns.

International Results with the Boston Type I Keratoprosthesis

PURPOSE To determine the indications and outcomes of Boston type 1 keratoprosthesis (Massachusetts Eye and Ear Infirmary, Boston, MA) surgery performed outside of North America and to compare them with those obtained in the United States by the surgeon who trained the international surgeons. DESIGN Retrospective review of consecutive clinical case series. PARTICIPANTS One hundred ninety-four patients (223 keratoprosthesis procedures performed in 205 eyes) who received Boston type 1 keratoprosthesis at 11 ophthalmology centers in Armenia, India, Indonesia, Nepal, Philippines, Russia, and Saudi Arabia between May 1, 2006, and July 1, 2011 (international series), and at the Jules Stein Eye Institute between May 1, 2004, and July 1, 2011 (University of California, Los Angeles [UCLA] series). METHODS Data were collected for each procedure regarding the preoperative characteristics of each eye, the surgical procedure(s) performed, and the postoperative outcomes. Statistical analysis was performed to identify significant differences between the international and UCLA series in terms of retention and complications. MAIN OUTCOME MEASURES Interval visual acuities, keratoprosthesis retention, and significant postoperative complications. RESULTS In the international series, 113 Boston type I keratoprostheses were implanted in 107 eyes of 100 patients. The most common indication for surgery was corneal graft failure (n = 50; 44%) followed by chemical injury (n = 30; 27%). Although only 2% of eyes had a preoperative corrected distance visual acuity (CDVA) of 20/20 to 20/200, 70%, 68%, and 59% of eyes had a postoperative CDVA of 20/20 to 20/200 at 6 months, 1 year, and 2 years after surgery, respectively. Ninety-one of the 113 keratoprostheses implanted (80.5%) were retained at a mean follow-up of 14.2 months, for a retention failure rate of 22 per 134.6 eye-years (0.163/eye-year). The most common postoperative complications were retroprosthetic membrane formation (27%) and sterile corneal necrosis (18%). The only postoperative complication that was more common in the international series than in the UCLA series was infectious endophthalmitis, which developed in 9% of eyes. CONCLUSIONS Boston keratoprosthesis is a viable means of managing repeat graft failure and ocular chemical injury outside of North America, with similar visual acuity outcomes, retention rates, and incidence rates of postoperative complications to those obtained by North American surgeons.

Keratoconus: current perspectives

Keratoconus is characterized by progressive corneal protrusion and thinning, leading to irregular astigmatism and impairment in visual function. The etiology and pathogenesis of the condition are not fully understood. However, significant strides have been made in early clinical detection of the disease, as well as towards providing optimal optical and surgical correction for improving the quality of vision in affected patients. The past two decades, in particular, have seen exciting new developments promising to alter the natural history of keratoconus in a favorable way for the first time. This comprehensive review focuses on analyzing the role of advanced imaging techniques in the diagnosis and treatment of keratoconus and evaluating the evidence supporting or refuting the efficacy of therapeutic advances for keratoconus, such as newer contact lens designs, collagen crosslinking, deep anterior lamellar keratoplasty, intracorneal ring segments, photorefractive keratectomy, and phakic intraocular lenses.

Clinical Outcomes of Repeat Autologous Cultivated Limbal Epithelial Transplantation for Ocular Surface Burns

PURPOSE To report the clinical outcomes of repeat autologous cultivated limbal epithelial transplantation in patients with recurrence of limbal stem cell deficiency after a failed primary procedure. DESIGN Retrospective case series. METHODS This study included 50 patients, above 8 years of age, with clinically diagnosed unilateral limbal stem cell deficiency following ocular surface burns, treated between 2001 and 2010. Following failure of primary surgery all patients underwent a repeat limbal biopsy from the unaffected eye. The limbal cells were expanded ex vivo on a human amniotic membrane substrate for 10 to 14 days using a completely xeno-free explant culture technique. The resulting cultured epithelial monolayer and amniotic membrane were transplanted onto the patients affected eye. All patients underwent a comprehensive ophthalmic examination of both eyes at every follow-up visit. Postoperative corneal surface stability, change in visual acuity, and complications were objectively analyzed. RESULTS At a mean follow-up of 2.3±1.4 (median: 1.96, range: 1 to 7.5) years, 33 of the 50 recipient eyes (66%) maintained a completely epithelialized, avascular, and clinically stable corneal surface. A 2-line improvement in visual acuity was seen in 38 of the 50 recipient eyes (76%). None of the donor eyes developed any clinical features of ocular surface disease, conjunctival overgrowth of the donor site, or decrease in vision throughout the follow-up period. CONCLUSIONS Repeat autologous cultivated limbal epithelial transplantation successfully restores corneal epithelial stability and improves vision in eyes with recurrence of limbal stem cell deficiency, following failed primary surgery for ocular burns, without adversely affecting donor eyes.

Cultivated Limbal Epithelial Transplantation in Children With Ocular Surface Burns

IMPORTANCE Although several reports are available on the use of conventional and cultured limbal epithelium using various substrates in the treatment of limbal stem cell deficiency (LSCD), the patient populations studied have been largely adults. Thus, to our knowledge, the outcomes of this procedure exclusively in a pediatric population have not been reported previously. OBJECTIVE To report the outcomes of autologous ex vivo cultivated limbal epithelial transplantation (CLET) in pediatric patients with LSCD after ocular burns. DESIGN AND SETTING A retrospective, interventional case series of patients treated at the L. V. Prasad Eye Institute, Hyderabad, India. PARTICIPANTS Children up to 15 years with LSCD secondary to chemical or thermal injury who underwent CLET from April 1, 2001, through June 31, 2010, with a follow-up of at least 1 year, were included in the study. INTERVENTION After a limbal biopsy specimen obtained from a healthy area of the limbus, the limbal epithelial cells were cultured on a denuded human amniotic membrane substrate using a xeno-free explant culture technique. A monolayer of cultivated epithelial cells along with the amniotic membrane was transplanted on the patients affected eye after pannus excision. In cases of failure, the same procedure was repeated. MAIN OUTCOMES AND MEASURES Ocular surface stability and visual improvement were the primary and secondary outcome measures, respectively. Success was defined as a stable corneal epithelium without conjunctivalization. Eyes with conjunctivalization and persistent epithelial defects were classified as failures. RESULTS Of the 107 eyes of 107 patients included in this study, 73 eyes (68.2%) underwent 1 and 34 eyes (31.8%) underwent 2 autologous CLET procedures. At a mean follow-up of 3.4 years, 50 eyes (46.7%) achieved completely epithelialized, avascular, and stable ocular surfaces. At the final visit, 58 eyes (54.2%) had improvement in visual acuity of 0.2 or more logMAR units. CONCLUSIONS Autologous CLET was successful in restoring the ocular surface and improving vision in almost half of the children blinded by ocular burns.

Clinical Outcomes of Penetrating Keratoplasty After Autologous Cultivated Limbal Epithelial Transplantation for Ocular Surface Burns

PURPOSE To report the clinical outcomes of penetrating keratoplasty (PK) after autologous cultivated limbal epithelial transplantation in eyes with limbal stem cell deficiency (LSCD) after ocular surface burns. DESIGN Retrospective case series. METHODS This study included 47 patients with unilateral LSCD treated by autologous cultivated limbal epithelial transplantation and PK between 2001 and 2010. PK was performed either along with (single-stage; n = 12) or at least 6 weeks after (2-stage; n = 35) limbal transplantation. The primary outcome measure was corneal allograft survival, and failure was defined clinically as loss of central graft clarity. Secondary outcomes were postoperative Snellen visual acuity and complications. RESULTS Most patients were young (mean age, 18 ± 11.4 years) males (76.6%) with LSCD resulting from alkali burns (78.7%) and with visual acuity less than 20/200 (91.5%). The mean follow-up was 4.2 ± 1.9 years. Kaplan-Meier corneal allograft survival rate at 1 year was significantly greater in eyes undergoing 2-stage limbal and corneal transplantation (80 ± 6%; median survival, 4 years) compared with single-stage limbal and corneal transplantation (25 ± 13%; median survival, 6 months; P = .0003). Visual acuity of 20/40 or better was attained by 71.4% of eyes with clear corneal grafts. Allograft failure occurred in 26 (60.5%) eyes as a result of graft rejection (57.7%), graft infiltrate (26.9%), or persistent epithelial defects (15.4%). Recurrence of LSCD was more common after single-stage (58.3%) than 2-stage (14.3%) surgery (P = .008). CONCLUSIONS The 2-stage approach of autologous cultivated limbal epithelial transplantation followed by PK successfully restores ocular surface stability and vision in eyes with chronic ocular burns. The single-stage approach is associated with poorer clinical outcomes and should be avoided.

Clinical outcomes of xeno-free allogeneic cultivated limbal epithelial transplantation for bilateral limbal stem cell deficiency

Purpose To report the clinical outcomes of allogeneic cell-based therapy for bilateral corneal blindness due to limbal stem cell deficiency (LSCD). Methods This retrospective study included 28 eyes of 21 patients, at least 8 years of age, with bilateral and total LSCD, treated between 2001 and 2010. A limbal biopsy was obtained from the eye of an adult living related donor. The limbal epithelial cells were cultivated in the laboratory using a xeno-free explant culture technique and transplanted onto the recipient eye after 10–14 days. All transplant recipients received topical and systemic immunosuppressants. Results At a mean follow-up of 4.8±2.8 years, 20 (71.4%) eyes maintained a completely epithelised, avascular and stable corneal surface, and among them 13 (46.4%) eyes subsequently underwent a penetrating keratoplasty (PK). The Kaplan–Meier survival rate of the PK allograft was 76.9±11.7% at 1 year with a median survival of 3.3 years. Visual acuity improved to 20/60 or better in 19 (67.8%) eyes. No donor or recipient eyes developed serious ocular complications. Conclusions Allogeneic cultivated limbal epithelial transplantation, followed by PK when needed, can successfully restore the ocular surface and improve vision in patients with corneal blindness due to bilateral LSCD.

Intracameral Perfluoropropane Gas in the Treatment of Acute Corneal Hydrops

PURPOSE This study is aimed to evaluate the role of 14% nonexpansile concentration of perfluoropropane (C(3)F(8)) gas in the management of acute hydrops in corneal ectasias. DESIGN Retrospective, nonrandomized, comparative, interventional case series. PARTICIPANTS AND CONTROLS The study group consisted of 62 eyes of 57 patients and the control group included 90 eyes of 82 patients with acute corneal hydrops who presented within 30 days of onset of symptoms. INTERVENTION Patients in the control group underwent a single intracameral injection of 0.1 mL of nonexpansile concentration (14%) of C(3)F(8) gas. Patients in the control group were treated conservatively. Patients in both groups were followed regularly for 12.6±7.7 and 13.4±8.3 months in the study and control groups, respectively, and assessed clinically for complete disappearance of epithelial and stromal edema on slit-lamp biomicroscopy. MAIN OUTCOME MEASURES The primary outcome measure was mean time to resolution of corneal edema, which was calculated both from the date of onset of hydrops and the date of initiation of therapy to the date of resolution in days. RESULTS The overall time to resolution both from the date of onset of symptoms (90.5±55.8 vs 125±68.9 days; P = 0.0005) and from the date of initiation of therapy (78.7±53.2 vs 117.9±68.2 days; P = 0.0001) was significantly lower in the study group compared with the control group. However, on subgroup analysis a significant difference in the resolution time was found only in eyes with keratoconus (P<0.0001). No difference in the resolution time was seen in eyes with pellucid marginal corneal degeneration (PMCD) or keratoglobus. The main complication of this procedure was reversible pupillary block (16%; P<0.0001). There was no difference in the final visual acuity or endothelial cell counts between the 2 groups. CONCLUSIONS Intracameral C(3)F(8) gas in a nonexpansile concentration is a useful modality for faster resolution of corneal edema in patients with acute corneal hydrops and keratoconus, and its role in the treatment of PMCD and keratoglobus needs further evaluation.

Concise Review: The Coming of Age of Stem Cell Treatment for Corneal Surface Damage

The cornea is a vital component of the eye because it provides approximately 70% of the refraction and focusing of incoming light. Being the outermost surface of the eye, it faces continuous stress from dryness, photodamage, infection, and injury; however, like the skin, the cornea regularly refreshes itself by shedding its epithelial cells, which are readily replaced, keeping the ocular surface stable and functional. This regular turnover of the corneal epithelial cells occurs through the stem cells in the limbus, an annular ring of a tissue surrounding the cornea, separating it from the sclera and the conjunctival membrane. The loss of this reserve of stem cells leads to a condition called limbal stem cell deficiency. Treatment for this disorder has evolved from transplanting whole limbal tissues to the affected eye to transplanting laboratory cultured limbal cells. This procedure is called cultivated limbal epithelial transplantation (CLET). Since its start in 1997, more than 1,000 CLET procedures have been reported from around the world, with varying degrees of success. In this paper, we compare the methods of cultivation and the outcomes and discuss some problem areas, use of other cells as substitutes for limbal epithelium, and various carrier materials used in transplantation. Our analysis suggests that CLET as a treatment for corneal surface damage has come of age. We also highlight a simpler procedure (simple limbal epithelial transplantation) that involves cultivation of limbal tissue in situ on the surface of the cornea in vivo and that has outcomes comparable to CLET.