Scheffer C. G. Tseng

LIMBAL AUTOGRAFT TRANSPLANTATION FOR OCULAR SURFACE DISORDERS

Limbal autograft transplantation is presented in 26 consecutive cases comprising both acute and chronic chemical injury (20 cases), thermal burns (2 cases), contact lens-induced keratopathy (3 cases), and ocular surface failure after multiple surgical procedures (1 case), with follow-up ranging from 2 to 45 months (mean, 18 months). The operative technique usually involved transfer of two free grafts of limbal tissue from the uninjured or less injured donor eye to the severely injured recipient eye, the latter having been prepared by limited conjunctival research and superficial dissection of fibrovascular pannus without keratectomy. Clinical results in 21 patients with follow-up of 6 months or more have consistently shown improved visual acuity (17 cases), rapid surface healing (19 cases), stable epithelial adhesion without recurrent erosion or persistent epithelial defect (20 cases), arrest or regression of corneal neovascularization (15 cases), and probable increased success for lamellar or penetrating keratoplasty (8 cases). No intraoperative complications were encountered, and no adverse reactions developed in donor eyes. Impression cytology in selected cases showed restoration of the corneal epithelial phenotype and regression of goblet cells from the recipient cornea. Therefore, limbal autograft transplantation is recommended for treatment of widespread ocular surface damage with loss of limbal epithelial stem cells and, specifically, for chemical or thermal burns, contact lens-induced keratopathy, and selected persistent corneal epithelial defects.

Transplantation of preserved human amniotic membrane for surface reconstruction in severely damaged rabbit corneas

After n-heptanol removal of the total corneal epithelium and a limbal lamellar keratectomy, 23 rabbit eyes developed features of limbal stem cell deficiency including conjunctival epithelial ingrowth, vascularization and chronic inflammation. One month later, 10 control eyes received a total keratectomy, and 13 experimental eyes received additional transplantation of glycerin-preserved human amniotic membrane. In 3 months of follow-up, all control corneas were revascularized to the center with granuloma and retained a conjunctival epithelial phenotype. In contrast, five corneas in the experimental group became clear with either minimal or no vascularization; the rest had either mid peripheral (n = 5) or total (n = 3) vascularization and cloudier stroma. The success of corneal surface reconstruction correlated with the return of a cornea-like epithelial phenotype and the preservation of amniotic membrane, whereas the failure maintained a conjunctival epithelial phenotype and the amniotic membrane was either partially degraded or covered by host fibrovascular stroma. These results suggest that measures taken to facilitate epithelialization without allowing host fibrovascular ingrowth onto the amniotic membrane might prove this procedure clinically useful for ocular surface reconstruction.

AMNIOTIC MEMBRANE TRANSPLANTATION FOR PERSISTENT EPITHELIAL DEFECTS WITH ULCERATION

PURPOSE To determine whether preserved human amniotic membrane can be used as an alternative substrate for treating persistent corneal epithelial defects with sterile ulceration. METHODS Amniotic membrane transplantation was performed in 11 eyes of 11 consecutive patients with corneal ulcers of different causes that had persisted for a mean +/- SD of 17.5 +/- 13.9 weeks. RESULTS Ten patients healed in 3.9 +/- 2.3 weeks (P < .01) without recurrence for 9.0 +/- 5.9 months. One patient failed to heal because of preexisting corneal perforation pursuant to severe rheumatoid arthritis. CONCLUSION Amniotic membrane transplantation may be considered an alternative method for treating persistent epithelial defects and sterile ulceration that are refractory to conventional treatment and before considering treatment by conjunctival flaps or tarsorrhaphy.

Concept and application of limbal stem cells

Cumulative reported evidence indicates that some fraction of limbal basal epithelial cells are the stem cells for corneal epithelial cell proliferation and differentiation. Limbal epithelium is therefore crucial in maintaining the cell mass of corneal epithelium under normal conditions and plays an important role in corneal epithelial wound healing. Deficiency or absence of limbal stem cells explains well the pathogenesis of several ocular surface disorders characterised by defective conjunctival transdifferentiation or conjunctivalisation of cornea. This paper reviews and updates the basic concept of stem cells, the reported findings of limbal stem cells for corneal epithelium, and their therapeutic applications. Through this review, one hopes to gain a more complete understanding and increase proficiency in treating these diseases.

Comparison of Conjunctival Autografts, Amniotic Membrane Grafts, and Primary Closure for Pterygium Excision

OBJECTIVE The purpose of the study is to determine whether amniotic membrane can be used as an alternative to conjunctival autograft after pterygium excision. DESIGN A prospective study of amniotic membrane grafts (group A) and primary closure (group B) was compared retrospectively with conjunctival autografts (group C) in patients with pterygia. PARTICIPANTS Group A included 46 eyes with primary pterygia and 8 eyes with recurrent pterygia, group B had 20 eyes with primary pterygia, and group C consisted of 78 eyes with primary and 44 eyes with recurrent pterygia. INTERVENTION For the above three different surgeries, the amount of tissue removed was estimated from histopathologic analysis, and the result was evaluated by clinical examination. MAIN OUTCOME MEASURES Recurrence, survival analysis, and final appearance were compared. RESULTS In group A, the recurrence rate was 10.9%, 37.5%, and 14.8% for primary, recurrent, and all pterygia, respectively (mean follow-up, 11 months). These three rates were significantly higher than 2.6%, 9.1%, and 4.9% noted in group C (mean follow-up, 23 months) (P < 0.001, 0.018, and 0.01, respectively). However, the latter recurrence rate was significantly lower than 45% (mean follow-up, 5.2 months) in group B for primary pterygia (P < 0.001). The onset of recurrence was delayed significantly in group C as compared with that of groups A and B. CONCLUSIONS The relatively low recurrence rate for primary pterygia allows one to use amniotic membrane transplantation as an alternative first choice, especially for advanced cases with bilateral heads or those who might need glaucoma surgery later.

Evaluation of subjective assessments and objective diagnostic tests for diagnosing tear-film disorders known to cause ocular irritation.

Purpose To determine which subjective assessments and objective tests have clinical utility as diagnostic tools in ocular irritation associated with Sjögrens syndrome—related aqueous tear deficiency (ATD), non-Sjögren ATD, inflammatory meibomian gland disease (MGD) associated with rosacea, and atrophic MGD. Methods Forty adults with ocular irritation and 10 with normal ocular surfaces were enrolled in a nonrandomized, nonblinded clinical trial. Symptoms were evaluated. Tests included biomicroscopy; evaluation of tear-film integrity, production, and clearance; fluorescein and rose bengal staining; and serum autoantibody screening. Results Symptoms were similar among groups and most severe in the Sjögrens group. Fluorescein tear break-up time was significantly faster in the ATD and MGD groups than that in controls. Schirmer scores were significantly lower in the ATD group than those in MGD and control groups. Tear clearance was delayed in the ATD and atrophic MGD groups. Xeroscope grid distortion was noted only with ATD. The Sjögrens group had greater loss of nasolacrimal reflex, slower fluorescein clearance, and greater ocular-surface fluorescein and rose bengal staining than did the others. More MGD subjects had meibomian gland orifice metaplasia and acinar dropout than did those with Sjögren-related ATD and controls. Schirmer scores correlated inversely with rose bengal staining, corneal fluorescein staining, and grid distortion. Rose bengal staining correlated with grid distortion and loss of nasal—lacrimal reflex, but not with MGD. Conclusion Subjective assessments and objective diagnostic tests have clinical utility as diagnostic tools in tear-film disorders. ATD is correlated with ocular-surface disease. An algorithm summarizing the diagnostic utility of these tests is included.

Cytologlogic Evidence of Corneal Diseases with Limbal Stem Cell Deficiency

Purpose: To determine which human corneal diseases show similar abnormal corneal surfaces, characterized by conjunctival epithelial ingrowth (conjunctivalization), vascularization, and chronic keratitis (i.e., a constellation of signs termed limbal stem cell dysfunction [deficiency], which have been noted in experimental rabbit models). Methods: A total of 134 impression cytology specimens of the perilimbal region collected from 1984 to 1994 were reviewed. Limbal deficiency was diagnosed if conjunctival goblet cells were found on the corneal surface. Results: Ninety-four patients were found to have limbal deficiency. Category 1 comprised 53 patients with a clear history showing limbal stem cell destruction by chemical/thermal burns, Stevens-Johnson syndrome, multiple surgeries and cryotherapies, contact lens wear, and severe microbial keratitis. Patients in category 2 (n = 41), did not have such a history, but gradual loss of stem cell functions overtime was disclosed and included diverse causes such as aniridia, multiple endocrine deficiencies, neurotrophic keratopathy, peripheral inflammatory keratopathy or limbitis, and idiopathy. The 40 remaining patients with suspicious findings did not have limbal deficiency. Conclusions: Impression cytology can be used to diagnose and monitor corneal diseases with limbal deficiency, which manifest distinct clinical problems and are generally poor candidates for penetrating keratoplasty. The identification of category 1 diseases allows one to consider limbal (stem cell) transplantation for surface reconstruction. The presence of category 2 diseases indicates that limbal stem cell functions can be modulated by developmental, hormonal, neuronal, vascular, and inflammatory factors in the limbal stroma.

Suppression of transforming growth factor-beta isoforms, TGF-beta receptor type II, and myofibroblast differentiation in cultured human corneal and limbal fibroblasts by amniotic membrane matrix.

Down‐regulation of the transforming growth factor‐beta (TGF‐β) signaling system is a strategy for preventing scarring during wound healing. Human corneal and limbal fibroblasts were cultured on the stromal matrix side of preserved human amniotic membrane. The levels of TGF‐β1, β2, and β3 and TGF‐β type II receptor transcripts and TGF‐β1 and β2 proteins were suppressed as early as 8 hr and more dramatically at 24 hr after contact with an amniotic membrane. This suppressive effect was accompanied by down‐regulation of α‐smooth muscle actin, EDA spliced form of fibronectin, and integrin α5. It persisted even when challenged by 10 ng/ml TGF‐β1. In contrast with their counterparts grown on plastic or in collagen gel, such suppression in amniotic membrane cultures remained complete after 1 week of culturing. Cells cultured on amniotic membrane showed significantly reduced [3H]‐thymidine incorporation compared to cells cultured on plastic and displayed no DNA fragmentation. These results reveal a novel mechanism by which the TGF‐β signaling system, DNA synthesis, and subsequent myofibroblast differentiation can be suppressed by an amnionic membrane matrix. This action explains in part the antiscarring results of amniotic membrane transplantation used for ocular surface reconstruction, a surgical technique applicable to other subspecialties. It may also explain in part why fetal wound healing is scarless. J. Cell. Physiol. 179:325–335, 1999.

Amniotic Membrane Transplantation for Conjunctival Surface Reconstruction

PURPOSE To determine whether preserved human amniotic membrane can be used to reconstruct the conjunctival defect created during surgical removal of a large lesion or during symblepharon lysis. METHODS Amniotic membrane transplantation was performed in six consecutive patients (seven eyes) during removal of large conjunctival lesions and in nine patients (nine eyes) during removal of conjunctival scars or symblepharon. RESULTS During a mean follow-up period +/- SD of 10.9 +/- 9.1 months (range, 2.2 to 34.0 months), 10 patients (11 eyes) showed successful surface reconstruction without recurrence, five patients (five eyes) showed improved visual acuity, and one patient (one eye) showed epithelialization within 3 weeks and resolution of motility restriction. Two patients (two eyes) showed partial success, with surrounding conjunctival inflammation. Three cases (three eyes) failed and exhibited recurrent scarring: one patient had received mitomycin treatment and beta radiation, whereas the transplanted amniotic membrane of the second patient was partially, and of the third patient was completely, dissolved or replaced by the inflamed pseudopterygial tissue. Two patients (two eyes) had epithelial cyst formation. CONCLUSION Amniotic membrane transplantation can be considered an alternative substrate for conjunctival surface reconstruction during removal for large tumors, disfiguring scars, or symblepharon, especially for those whose surrounding conjunctival tissue remains relatively normal.

Dysfunctional Tear Syndrome A Delphi Approach to Treatment Recommendations

Purpose: To develop current treatment recommendations for dry eye disease from consensus of expert advice. Methods: Of 25 preselected international specialists on dry eye, 17 agreed to participate in a modified, 2-round Delphi panel approach. Based on available literature and standards of care, a survey was presented to each panelist. A two-thirds majority was used for consensus building from responses obtained. Treatment algorithms were created. Treatment recommendations for different types and severity levels of dry eye disease were the main outcome. Results: A new term for dry eye disease was proposed: dysfunctional tear syndrome (DTS). Treatment recommendations were based primarily on patient symptoms and signs. Available diagnostic tests were considered of secondary importance in guiding therapy. Development of algorithms was based on the presence or absence of lid margin disease and disturbances of tear distribution and clearance. Disease severity was considered the most important factor for treatment decision-making and was categorized into 4 levels. Severity was assessed on the basis of tear substitute requirements, symptoms of ocular discomfort, and visual disturbance. Clinical signs present in lids, tear film, conjunctiva, and cornea were also used for categorization of severity. Consensus was reached on treatment algorithms for DTS with and without concurrent lid disease. Conclusion: Panelist opinion relied on symptoms and signs (not tests) for selection of treatment strategies. Therapy is chosen to match disease severity and presence versus absence of lid margin disease or tear distribution and clearance disturbances.