Corneal Limbus Research Articles

Implantation of Human Peripheral Corneal Spheres into Cadaveric Human Corneal Tissue.

Stem and progenitor cells isolated from human limbal tissue can be cultured in vitro as spheres. These spheres have potential for use as transplantable elements for the repopulation of corneal tissue ( Mathan et al., 2016 ). Herein we describe the detailed protocol for the implantation of human corneal spheres into cadaveric human corneal tissue. This protocol describes the procedure for sphere formation and culture, preparation of tissue for sphere implantation, corneal limbus microsurgery and sphere implantation.

Morphology of the Corneal Limbus Following Standard and Accelerated Corneal Collagen Cross-Linking (9 mW/cm2) for Keratoconus.

To evaluate the morphological features of the corneal limbus as measured by in vivo confocal microscopy (IVCM) following standard and accelerated corneal collagen cross-linking (CXL) for keratoconus. Patients with progressive keratoconus scheduled to undergo standard CXL (group 1; 31 patients, 3 mW/cm, 370 nm, 30 minutes), or accelerated CXL (group 2; 20 patients, 9 mW/cm, 370 nm, 10 minutes) in the worse eye were included in this prospective study. Thirty eyes of 30 age-matched patients served as controls (group 3). All patient eyes underwent IVCM scanning of the central cornea and the inferior limbal area at baseline and 1, 3, and 6 months after CXL. After CXL, epithelial regrowth was complete by day 4 in both groups 1 and 2. There were no statistically significant differences between the baseline mean central corneal wing or basal cell density, limbus-palisade middle or basal cell densities of groups 1, 2, or 3. At postoperative months 1, 3, and 6, there were no statistically significant differences in either central or limbus-palisade epithelial cell densities or diameters in keratoconic eyes that underwent standard or accelerated CXL (P > 0.05). The morphology of the limbal cells was preserved as well. The morphology of limbus structures seems to be preserved following standard and accelerated CXL in short-term follow-up, as measured using IVCM.

Pterygium surgery using the principle of contact inhibition: results of 13 years\u2019 experience

PurposeTo report a technique to prevent pterygium recurrence using the principle of contact inhibition.MethodsTwo hundred and fifteen patients (232 eyes; average age, 64.1 years) with primary pterygia who underwent pterygium surgery at the Hara Eye Hospital between 1999 and 2012. We retrospectively evaluated the patients who underwent the following procedure to prevent pterygium recurrence. The surface conjunctiva on the pterygium body was not removed. After removing the pterygium body, by placing a narrow pedicle autoconjunctival flap along the corneal limbus and tying it tightly to the front area of the residual conjunctiva, there is no room for the active residual tissue to proliferate, thus preventing a recurrence by contact inhibition. The key factor is conjunctival suturing, which establishes face-to-face contact of both areas of cut conjunctival tissue. Mitomycin C is applied locally for 3 min intraoperatively and 5 days postoperatively. The main outcome measure was the prevention of pterygium recurrence using this technique.ResultsBy the end of the average follow-up of 5 years 4 months, three eyes (1.3%) had a recurrence. Among the 232 eyes, 23 eyes had large pterygia extending to the pupillary area. Using the surgical technique, there were no recurrences. No specific characteristic of the recurrence was found in association with the eye, sex, and preoperative grade.ConclusionsThis surgery has three relevant features: (1) reconfirmation of the effect of contact inhibition, (2) the anatomic structure of the conjunctival sac scarcely changes postoperatively, because the surface conjunctiva of the pterygium body is not removed, and (3) a low recurrence rate.

Analysis on correlative factors of sympathetic ophthalmia after ocular trauma

Objective To analyse the correlative factors of sympathetic ophthalmia after ocular trauma. Methods The statistical data about 20 eyes of 20 cases of sympathetic ophthalmia secondary to ocular trauma were studied and the related factors were analyzed. Results The corneoscleral wound leading to sympathetic ophthalmia accounted for the highest proportion of 75.00%. The patients were aged 7-56 years old and patients aged 7-12 years accounted for 50.00%. The sex ratio of male versus female was 3∶1. Conclusion The corneal limbus wound is in the majority among patients with sympathetic ophthalmia secondary to ocular trauma .The ocular trauma in children should be paid more attention to because of its particularity. Key words: Sympathetic ophthalmia, ocular trauma; Analysis, correlative factors

Abstracts: European Society of Veterinary Ophthalmologists, Toulouse, France, October 6‐9, 2016

Purpose: To evaluate the effects of 2% Dorzolamide, 0.5% Timolol and 0.005% Latano- prost on the biometrics of the anterior segment in normotensive cats. Material/Methods: Three groups of 15 clinically healthy randomly selected cats received one single molecule on the right eye during 7 days (Group 1: 2% Dorzolamide BID, Group 2: 0.5% Timolol BID, Group 3: 0.005% Latanoprost SID). Left eyes received no treatment and were used as con- trols. Complete ophthalmic examination, IOP measurement and anterior segment assessment by Ultrasound Biomicroscopy (UBM) were performed in the same conditions at day 1 and day 7, on both eyes. Eight anatomical parameters of the anterior segment were evaluated: the geometric iridocorneal angle (ICA) – formed by the plane of the iris root and the inter- nal corneoscleral limbus – the width of the opening of the ciliary cleft (CC), the width of the mid-CC, the length of the CC, the anterior chamber (AC) depth (distance between the corneal endothelium and the anterior lens capsule), the central and peripheral corneal thick- nesses, then the distance between the anterior lens capsule and the internal corneoscleral limbus. Results: The use of the controlateral eye as control was statistically validated, as well as the representativeness of fifteen-cat cohorts. A significant decrease of IOP was observed only for dorzolamide (5.3%). None of the eight anatomical parameters were statistically modified by the topical instillation of the three drugs. Discussion: The use of the three first-line antiglaucomatous agents does not significantly alter the anterior segment architecture in normotensive cats.

Imaging characteristics of the postoperative globe: a pictorial essay

Recognizing imaging characteristics after ophthalmic surgery is necessary for radiologists to prevent misdiagnosis. We review typical appearances of intraorbital implanted devices and materials on CT and MRI with demonstration of the common surgical procedures. EX-PRESS glaucoma filtration devices appear as punctate areas of metal attenuation on CT and are typically placed at the corneoscleral junction. The imaging manifestations after cataract extraction are absence of the native lens of ovoid mass and the intraocular lens with high attenuation on CT and low signal intensity on MRI. The treatment of retinal detachment is achieved with intraocular tamponade or scleral buckling. In intraocular tamponade, the eye is filled with a bubble of gas or silicone oil. Gas results in air attenuation on CT and low signal intensity on MRI in the vitreous cavity. Silicone oil is hyperattenuating on CT and has variable intensity on MRI. In scleral buckling, the eye wall is indented with silicone buckling elements that show high or low attenuation on CT and low T1- and T2-weighted intensity on MRI. Degraded hydrogel buckling elements appear as swollen masses showing low attenuation on CT and high T2-weighted intensity on MRI.

Cellular Stiffness as a Novel Stemness Marker in the Corneal Limbus

Healthy eyes contain a population of limbal stem cells (LSCs) that continuously renew the corneal epithelium. However, each year, 1 million Americans are afflicted with severely reduced visual acuity caused by corneal damage or disease, including LSC deficiency (LSCD). Recent advances in corneal transplant technology promise to repair the cornea by implanting healthy LSCs to encourage regeneration; however, success is limited to transplanted tissues that contain a sufficiently high percentage of LSCs. Attempts to screen limbal tissues for suitable implants using molecular stemness markers are confounded by the poorly understood signature of the LSC phenotype. For cells derived from the corneal limbus, we show that the performance of cell stiffness as a stemness indicator is on par with the performance of ΔNP63α, a common molecular marker. In combination with recent methods for sorting cells on a biophysical basis, the biomechanical stemness markers presented here may enable the rapid purification of LSCs from a heterogeneous population of corneal cells, thus potentially enabling clinicians and researchers to generate corneal transplants with sufficiently high fractions of LSCs, regardless of the LSC percentage in the donor tissue.

Limbus-insertion distance of superior rectus in primary angle closure glaucoma: an anterior segment OCT study

ObjectiveTo compare the distance from the corneoscleral limbus to the insertion site of the superior rectus of primary angle-closure glaucoma (PACG) patients with normal controls and to identify potential characteristics associated with limbus-insertion distance. DesignCross-sectional study. ParticipantsA total of 92 subjects (eyes) were enrolled in the study: 35 were nonglaucoma controls and 57 were PACG patients. MethodsThe limbus-insertion distance of the superior rectus was measured by anterior segment optical coherence tomography (AS-OCT) and intraoperative surgical caliper. The anterior chamber parameters were also measured using AS-OCT to identify potential characteristics associated with limbus-insertion distance. ResultsThe limbus-insertion distance of the superior rectus was 0.40 ± 0.08 mm shorter in the PACG group than in the normal control group (p < 0.001). Anterior segment parameter values, including anterior chamber depth (ACD), anterior chamber width (ACW), anterior chamber area (ACA), and anterior chamber volume (ACV), were smaller in the PACG group than in the normal control group, but the lens vault was larger (all p < 0.001). A shorter limbus-insertion distance of the superior rectus was significantly associated with shorter axial length and “crowded” angle (smaller ACD, ACW, ACA, and ACV) (all p < 0.05). ConclusionsThis is the first study to demonstrate that the limbus-insertion distance of the superior rectus was shorter in PACG eyes than in normal eyes. The shorter limbus-insertion distance may be another anatomic characteristic of PACG eyes.

Pterygium excision with conjunctival autograft and subconjunctival amniotic membrane as antirecurrence agents

ObjectiveTo determine the outcome of pterygium excision with a conjunctival autograft when the adjunctive use of a subconjunctival graft of amniotic membrane is employed to reduce fibrosis and recurrence after surgery. DesignThis is a retrospective, noncomparative study of postoperative outcomes. ParticipantsEighty-four patients totalling 101 eyes with clinically significant pterygia that warranted surgical excision. MethodsSurgeries were performed at South Orange County Outpatient Surgery Center (San Clemente, Calif.) between June 6, 2006, and October 23, 2013, by a single surgeon (J.A.H.). Patients were included in the study according to the need for pterygium surgery and the type of surgery performed. Exclusion criteria included patients with recurrent pterygium, those with pseudopterygium, and those whose treatment plan included prophylactic mitomycin during or after surgery. Initial pterygia measurements and postoperative findings were taken through standard slit-lamp examinations. ResultsPterygium recurrence was defined as growth greater than 1 mm onto the corneal limbus at or after 6 months. There was 1 case of pterygium recurrence for a recurrence rate of 0.99% ± 1.93% (n = 101, p = 0.05). The mean extent of preoperative horizontal encroachment of pterygium on the cornea was 2.4 ± 0.87 mm. ConclusionsPterygium excision with a conjunctival autograft and prophylactic placement of a subconjunctival amniotic membrane graft has a low recurrence rate with minimal added surgical time and minimal added risk to the patient and has merit as a surgical technique.

Clinical application of heart dacron patch in facial nerve paralytic ectropion after the surgery of acoustic neuroma

Objective To investigate the clinical application of heart dacron patch for the treatment of facial nerve paralytic ectropion after the surgery of acoustic neuroma. Methods The subcutaneous tunnel incision on lower eyelid was made at supratemporal inner canthus ligament and lateral canthus respectively, the heart dacron patch was fixed at supratemporal inner canthus ligament and lateral canthus respectively to make the palpebral margin locating 2 mm above the corneoscleral limbus. Results The postoperative follow-up was 6-12 months. The facial nerve paralytic ectropion after the surgery of acoustic neuroma was entirely corrected in 17 cases. No shift or prolapse of the implant occurred. The patients were satisfied with the surgical effect. Conclusion Pocket surgery with heart dacron patch for the treatment of facial nerve paralytic ectropion after the surgery of acoustic neuroma was simple and effective with less injury. It is a good surgical operation. Key words: Ectropion, paralytic; Acoustic neuroma; Surgery, after; Pocket surgery, heart dacron patch

Corneal Epithelial Stem Cells Repopulate the Donor Area within 1 Year from Limbus Removal for Limbal Autograft

To determine whether limbal epithelial stem cells (LESCs) repopulate the site harvested for limbal autograft transplantation (LAT), the expression of LESCs markers was evaluated in bioptic specimens obtained from the donor area 12 months or more after surgery. Interventional case series. Patients who underwent LAT for unilateral acquired limbal stem cell deficiency after chemical burn. Corneal limbal explants were obtained from 2 sites, the harvested area and the untouched control area, in the donor eyes of 6 patients who previously underwent LAT for unilateral acquired limbal stem cell deficiency after chemical burn. Limbal epithelial stem cells were isolated, and cellular, immunohistochemistry, and histologic parameters were assessed to compare differences between LESCs isolated from harvested or control sites. Presence of LESCs 1 year or more after LAT. Specific markers (p63, Ki67, K12), percentage of LESCs, cell doubling, and number of passages in culture did not differ significantly between harvested and control sites. However, the distinctive structure of the palisades of Vogt was found only in 2 of 6 harvested sites. Limbal epithelial stem cells repopulate the donor site as early as 1 year after limbus removal for LAT. Autologous transplantation of conjunctiva and limbus are safe procedures and can be performed in cases that cannot be treated by simple grafting of LESCs cultured exvivo.

Inhibiting the effect of (90)Sr-(90)Y ophthalmic applicators on rat corneal neovascularization induced by sutures.

To investigate a practical technique used to inhibit corneal angiogenesis with a (90)Sr-(90)Y ophthalmic applicator. A (90)Sr-(90)Y ophthalmic applicator was detected with a radioactive nuclide application treatment healthy protection standard. The applicator used was produced through medical dosimetry research; it had a concave applicator add measured the applicator temperature, serviceable humidity range, applicator appearance status, applicator radiation homogeneity, radioautography, and radiological safety of the original applicator surface. A vessel model was established using newborn rats, with sutures around the corneal limbus. Corneal neovascularization (CNV) were observed with a slit lamp. The new vessel length and response area were measured. Low-dose radiation can inhibit CNV after corneal sutures. The absorbed dose of the applicator (0.046 Gy/s) was safe for the treatment of it. The lengths of new vessels and the areas of new vessels were lower than the new born vessel rat group (P<0.01). The optimal radiation dose emitting from the applicator can be safe and potentially used in humans.

Applications of stem cell biology to oculoplastic surgery.

The review examines the utility of stem cell biology in ophthalmology and oculoplastic surgery. The applicability of stem cell biology varies across a range of different subfields within ophthalmology and oculoplastic surgery. Resident stem cells have been identified in the lacrimal gland, corneal limbus, orbital fat, and muscles of the eye, and can potentially be applied for in-vitro cell and organ cultures with the intent of disease modeling and transplants. The discovery of adipocyte-derived stem cells offered a potentially powerful tool for a variety of oculoplastic applications, such as wound healing, skin rejuvenation, and burn therapeutics. Several groups are currently identifying new uses for stem cells in oculoplastic surgery. The need for stem cell treatment spans a wide array of subfields within ophthalmology, ranging from reconstruction of the eyelid to the generation of artificial lacrimal glands and oncological therapeutics. The advent of induced pluripotent stem cells opened the realm of regenerative medicine, making the modeling of patient-specific diseases a possibility. The identification and characterization of endogenous stem cell populations in the eye makes it possible to obtain specific tissues through induced pluripotent stem cells differentiation, permitting their use in transplants for oculoplastic surgery.

Effect of Pilocarpine Hydrochloride on the Schlemm Canal in Healthy Eyes and Eyes With Open-Angle Glaucoma.

The in vivo effect of pilocarpine hydrochloride on the Schlemm canal may help explain its pharmacologic mechanism of action and better indicate its clinical use. To investigate the effect of pilocarpine on the structure of the Schlemm canal in vivo in healthy eyes and eyes with glaucoma. In this case-control study, healthy individuals and patients with open-angle glaucoma were prospectively enrolled between September 1, 2013, and June 30, 2014, after a complete ophthalmologic examination at a tertiary glaucoma referral practice. Eighty-one serial, horizontal, enhanced depth imaging optical coherence tomographic B-scans (interval between B-scans, approximately 35 µm) of the nasal corneoscleral limbus were performed before and 1 hour after topical administration of pilocarpine, 1%, in 1 eye of healthy volunteers and pilocarpine, 2%, in 1 eye of patients with glaucoma. Fifty B-scans in the overlapping area (circumferential length, approximately 1.7 mm) between the 2 sets of serial scans (before and after pilocarpine administration) were selected for analysis based on the structures of aqueous and blood vessels as landmarks. The cross-sectional area of the Schlemm canal was measured in each selected B-scan. Volume of the Schlemm canal was calculated using commercially available 3-dimensional reconstruction software. Mean cross-sectional area of the Schlemm canal. Enhanced depth imaging optical coherence tomographic scans of the Schlemm canal were performed successfully before and after administration of pilocarpine, 1%, in 9 healthy eyes (9 individuals) and pilocarpine, 2%, in 10 eyes with glaucoma (10 patients) (mean [SD] age, 31.9 [7.8] and 68.7 [13.2] years, respectively). Following pilocarpine administration, mean (SD) intraocular pressure decreased from 14.3 (1.3) to 13.7 (1.1) mm Hg in healthy eyes (P = .004) and from 17.5 (6.0) to 16.6 (6.1) mm Hg in eyes with glaucoma (P = .01). The mean (SD) cross-sectional area of the Schlemm canal increased by 21% (4667 [1704] to 5647 [1911] µm2) in healthy eyes (P < .001) and by 24% (3737 [679] to 4619 [692] µm2) in eyes with glaucoma (P < .001) (mean difference in percent increase, 2.2%; 95% CI, -8.5% to 12.9%). The mean (SD) volume of the Schlemm canal in the overlapping area increased from 8 004 000 (2 923 000) to 9 685 000 (3 277 000) µm3 in healthy eyes (P < .001) and from 6 468 000 (1 170 000) to 7 970 000 (1 199 000) µm3 in eyes with glaucoma (P < .001). These data suggest that pilocarpine expands the Schlemm canal in eyes with and without glaucoma. No differences in the effect were identified between the 2 groups. Enhanced depth imaging optical coherence tomography may be useful in investigating the effect of pharmacologic agents on the Schlemm canal.

Clinical analysis of the factors contributing to pupillary optic capture after transscleral fixation of posterior chamber intraocular lens for dislocated intraocular lens

To study the incidence of and risk factors for pupillary capture after transscleral fixation of a posterior chamber intraocular lens (PC IOL) for dislocated IOLs. Department of Ophthalmology, Kyungpook National University Hospital, Daegu, South Korea. Retrospective case series. Charts of patients who had PC IOL transscleral fixation for the treatment of dislocated IOLs between January 2010 and August 2015 were reviewed. Demographic data, anterior chamber depth (ACD), axial length (AL), anterior chamber volume (ACV), and anterior chamber angle (ACA) were recorded. The cases of postoperative pupillary capture were collected and the characteristic clinical findings evaluated. Charts of 63 eyes of 63 patients were reviewed. The mean age was 63years±11 (SD). The mean follow-up after transscleral fixation was 47.8±25.3months. There were 5 cases of postoperative pupillary capture (incidence 7.8%). A deeper anterior chamber was statistically correlated with an increased incidence of pupillary capture (β coefficient: 0.423; 95% confidence interval, 0.043-0.379; P<.015). There were no significant differences in the incidence of postoperative pupillary capture and age, sex, intraocular pressure, corrected visual acuity, astigmatism, AL, ACV, ACA, trauma history, associated ocular morbidity, or general comorbidity. To reduce the incidence of pupillary capture when ACD values are large, the scleral penetrating point should be adjusted from the corneal limbus. Neither author has a financial or proprietary interest in any material or method mentioned.

Correlation between the Limbus-Insertion Distance of the Lateral Rectus Muscle and Lateral Rectus Recession Surgery in Intermittent Exotropia.

The aim of this study was to investigate whether the limbus-insertion distance (LID) of the lateral rectus (LR) muscle can be a useful indicator for predicting the surgical effect of recession surgery in intermittent exotropia (IXT). Patients who underwent unilateral or bilateral LR recession for the basic type of IXT were included. The distance between the corneal limbus and the posterior edge of the insertion of LR muscle (limbus-insertion distance) was measured intraoperatively using surgical calipers (graded with 0.25 mm precision). We calculated the actual dose-response effect as the difference between the angle of preoperative deviation and the angle of postoperative deviation, and then divided the figure by the total amount of recession at postoperative months 1, 3, and 6. The correlation between the limbus-insertion distance (LID) of LR muscle and each dose-response effect was statistically analyzed. A total of 60 subjects were enrolled in this study. The mean LID of LR muscle was 5.8±0.7 mm. The dose-response effect was 3.2±1.0 prism diopters (PD)/mm at postoperative month 1, 3.4±1.0 PD/mm at postoperative month 3, and 3.4±1.1 PD/mm at postoperative month 6. The LID of the LR muscle was significantly correlated with dose-response effects in cases of unilateral and bilateral LR recession at postoperative months 3 and 6 (P = 0.01, <0.01, 0.04 and <0.01 respectively). As the LID of the LR muscle increased by 1 mm, the dose-response effect increased by 0.2PD/mm in unilateral LR recession, and by 0.4 PD/mm in bilateral LR recession at postoperative month 6. In conclusion, the LID of the LR muscle can be used as one predictor of the recession effect to assist in surgical planning for IXT. Moreover, undercorrection at the time of LR recession might be considered in patients with long LID of the LR muscle.

Method for Angiographically Guided Fine-Needle Diathermy in the Treatment of Corneal Neovascularization.

To describe a method to assess corneal neovascular (CoNV) complexes and identify feeder vessels for selective arterial fine-needle diathermy (FND). In patients with CoNV, color photography and corneal indocyanine green angiography (ICGA) and fluorescein angiography are performed. After injection of indocyanine green and sodium fluorescein dye, videography and single-frame images of the region of interest are recorded. Videography is used to measure the time to leakage to assess vessel maturity to guide medical treatment and to discern afferent from efferent vessels. Single-frame images are then selected to locate the number of afferent vessels for surgery, which are selectively cut with a 25-gauge marked needle for the application of FND. Angiography using fluorescein and indocyanine green allows the characterization of CoNV based on assessment of both morphologic (ICGA) and functional (fluorescein angiography) parameters. The time to leakage of fluorescein dye provides important functional information on vessel maturity and helps discern whether medical treatment should be followed before surgical. ICGA allows the identification and delineation of afferent feeder vessels even in the presence of corneal opacities affecting biomicroscopic visibility. Colocalizing the afferent vessel to a visible venous landmark or branch is helpful for placement of the incision and application of FND. Using the described approach, angiographically identified feeder vessels can be selectively treated by FND with minimal thermal energy applied to the corneoscleral limbus. The described method for angiographically guided assessment of CoNV is a useful approach for guiding the medical and surgical treatment of CoNV.

Angular Relations of Upper Corneal Coverage by Upper Lid Margin in Relation to Central Corneal Reflex in Normal Subjects of Shimla Hills

Aim: To study relations of Upper Lid Margin in relation to Central Corneal Reflex (CCR) in normal healthy subjects of Shimla Hills. Design: Comparative Case series involving 800 eyes of 400 subjects attending the OPD, were divided into four equal groups, males &lt;18 years, females &lt;18 years, males ≥18 years but &lt;35 years and females ≥18 years but &lt;35 years into group A, B, C and D respectively. The angular relations of upper lid (UL) in relation to CCR were calculated in computer using Goniometer, after magnifying images taken from Sony Super Steady Shot 8 megapixel Digital Camera. Three reference points on UL were taken from the spots where the UL touches the nasal side of corneal limbus (N), on temporal side of corneal limbus (T) and the midpoint of UL (point M). Then a point was taken from CCR (R). Angles thus formed on joining the above points i.e. NRT, MRT and NRM were measured using Goniometer. Results: Angle NRM values had an overall mean of 69.87°±5.75° Angle MRT values had overall mean of 58.41°±5.59° Angle NRT values had an overall mean of 128.13°±10.49°. Conclusion: Angle MRT is more or less constant in all ages and in both sexesAngle NRM variations are seen with advancing age especially among females.Angle NRT which is constituted by angles MRT and NRM, varies with advancing age and especially in females. These findings may be taken into account in preoperative assessment and while planning postoperative outcome in all surgical procedures of eyelid, like ptosis correction.

Long-term outcomes of wedge resection at the limbus for high irregular corneal astigmatism after repaired corneal laceration

To evaluate the clinical value of wedge resection at corneal limbus in patients with traumatic corneal scarring and high irregular astigmatism. Patients with traumatic corneal astigmatism received wedge resection at least 6mo after suture removal from corneal wound. The uncorrected distance visual acuities (UCVA) and best corrected distance visual acuities (BCVA), pre- and post-operation astigmatism, spherical equivalent (SE), safety and complications were evaluated. Ten eyes (10 patients) were enrolled in this study. Mean follow-up time after wedge resection was 37.8±15.4mo (range, 20-61mo). The mean UCVA improved from +1.07±0.55 logMAR to +0.43±0.22 logMAR (P=0.000) and the mean BCVA from +0.50±0.30 logMAR to +0.15±0.17 logMAR (P=0.000). The mean astigmatism power measured by retinoscopy was -2.03±2.27 D postoperatively and -2.83±4.52 D preoperatively (P=0.310). The mean SE was -0.74±1.61 D postoperatively and -0.64±1.89 D preoperatively (P=0.601). Two cases developed mild pannus near the sutures. No corneal perforation, infectious keratitis or wound gape occurred. Corneal-scleral limbal wedge resection with compression suture is a safe, effective treatment for poor patients with high irregular corneal astigmatism after corneal-scleral penetrating injury. Retinoscopy can prove particularly useful for high irregular corneal astigmatism when other measurements are not amenable.

Sphere-forming cells from peripheral cornea demonstrate the ability to repopulate the ocular surface.

BackgroundThe limbus forms the outer rim of the cornea at the corneoscleral junction and harbours a population of stem cells for corneal maintenance. Injuries to the limbus, through disease or accidents such as chemical injuries or burns, may lead to significant visual impairment due to depletion of the native stem cells of the tissue.MethodsSphere-forming cells were isolated from peripheral cornea for potential use as transplantable elements for limbal stem cell repopulation and limbal reconstruction. Immunocytochemistry, live cell imaging and quantitative PCR were used to characterize spheres and elucidate activity post implantation into human cadaveric corneal tissue.ResultsSpheres stained positively for stem cell markers ∆NP63α, ABCG2 and ABCB5 as well as the basal limbal marker and putative niche marker, notch 1. In addition, spheres also stained positively for markers of corneal cells, vimentin, keratin 3, keratocan and laminin, indicating a heterogeneous mix of stromal and epithelial-origin cells. Upon implantation into decellularized corneoscleral tissue, 3D, polarized and radially orientated cell migration with cell proliferation was observed. Cells migrated out from the spheres and repopulated the entire corneal surface over 14 days. Post-implantation analysis revealed qualitative evidence of stem, stromal and epithelial cell markers while quantitative PCR showed a quantitative reduction in keratocan and laminin expression indicative of an enhanced progenitor cell response. Proliferation, quantified by PCNA expression, significantly increased at 4 days subsequently followed by a decrease at day 7 post implantation.ConclusionThese observations suggest great promise for the potential of peripheral corneal spheres as transplantable units for corneal repair, targeting ocular surface regeneration and stem cell repopulation.