Naing L. Tint

Limbal epithelial crypt: a model for corneal epithelial maintenance and novel limbal regional variations.

OBJECTIVE To determine the distribution of cell membrane proteins and extracellular matrix proteins around the limbal epithelial crypt (LEC) compared with adjacent limbus and corneal epithelium. METHODS Serial histological sections of human corneoscleral limbus rims were stained with antibodies of interest by standard immunohistochemistry. RESULTS Superficial cells of the limbus were desmoglein 3 positive, compared with the negative basal cells of the limbus that correspond to cells with more stemlike properties. The LEC had a much lower proportion of desmoglein 3 staining in comparison. Tenascin C staining demonstrated regional variations of the limbus depending on their association with the LEC. Limbus that was associated with or adjacent to the LEC had a greater tenascin C expression compared with normal limbus, whereas the LEC demonstrated the greatest tenascin C expression. CONCLUSIONS Based on these and similar results previously reported for connexin 43, we propose a novel model on the mechanism of corneal surface epithelium maintenance involving 3 different limbal regions: zone 1, limbus including the LEC; zone 2, limbus associated with the LEC; and zone 3, limbus distant to the LEC. CLINICAL RELEVANCE The noted limbal variations may influence the selection of the donor site for limbal grafts in the future.

Hormone therapy and intraocular pressure in nonglaucomatous eyes.

Objective: The influence of sex hormones on intraocular pressure (IOP) has been the focus of recent debate. Previous studies investigating the effects of hormone therapy (HT) on IOP in postmenopausal women have produced conflicting results but have been limited by small numbers of participants. The aim of our study was to compare IOP in women without glaucoma taking HT with those not taking HT. Methods: A prospective cross-sectional study of postmenopausal women visiting a single ophthalmic medical practitioner was conducted. All women with a history of intraocular disease, a family history of glaucoma, or refractive error exceeding ±5 diopters were excluded. Applanation tonometry was used to measure IOP, and participants were then asked if they were current HT users. Results: A total of 263 participants were recruited, of whom 91 reported current use of HT; 172 had never used HT. Within the HT group, 33 were taking an estrogen-therapy and 58 were taking a estrogen-progesterone therapy. Mean IOP in the HT group was significantly lower than that in the non-HT group; the mean difference was 1.41 mm Hg (P < 0.001). This difference remained statistically significant after statistical correction for age, use of systemic &bgr;-blockers, and time of IOP measurement. There was no significant difference in mean IOP between women taking combined versus those taking estrogen-only preparations. Conclusions: Our study showed that IOP was significantly lower in women taking HT than in those who had never taken HT, even after removing other possible influences on IOP. The IOP-lowering effect of HT deserves further investigation to explore whether it may represent a possible new therapeutic modality for glaucoma.

Management of intraoperative floppy-iris syndrome-associated iris prolapse using a single iris retractor

Tamsulosin is an alpha(1)-adrenergic antagonist known to be linked with intraoperative floppy-iris syndrome (IFIS), which is characterized by iris atonicity and a propensity toward progressive intraoperative pupil constriction and iris prolapse. We present 2 strategies for managing IFIS-associated iris prolapse. Placement of a single subincisional iris retractor following reposition of the prolapsed iris was the more successful approach. We recommend consideration of this approach in all cases of iris prolapse.

Eyelid avulsion repair with bi-canalicular silicone stenting without medial canthal tendon reconstruction

Aims To evaluate the functional and cosmetic success rate of combined canalicular laceration and eyelid avulsion repairs using the bi-canalicular Crawford stent, without the concomitant placement of a medial traction suture to repair medial canthal tendon (posterior limb) avulsion. Methods Retrospective, non-comparative consecutive case series of 40 consecutive patients with traumatic eyelid avulsion injuries associated with canalicular laceration from 1997 to 2003 who underwent surgical repair using the bi-canalicular Crawford stent were included. All patients underwent surgical repair of the canalicular laceration under general anaesthesia using the bi-canalicular stent. Meticulous anastomosis of the torn canaliculus was undertaken. No attempt was made to suture the avulsed medial canthal tendon (posterior limb) to the periosteum of the posterior lacrimal crest. Results Blunt trauma was the most common mechanism of injury and the inferior canaliculus was most commonly involved. Of the 37 patients who attended postoperative follow-up, 24 patients had no subjective symptoms of epiphora. Minimal, mild and moderate epiphora was present in seven, five and one patient respectively. Thirty-three patients had excellent cosmetic repositioning of the lid; two developed medial ectropia and a further two patients had lid margin notching but good lid position. Eight patients had premature stent loss. Conclusions Bi-canalicular stenting achieved excellent cosmetic results in eyelid avulsion injuries, by facilitating adequate tissue realignment without the need for a posterior lacrimal crest fixation suture. Good functional results were achieved and were comparable with previous studies.

Severe conjunctivochalasis in association with classic type Ehlers-Danlos syndrome

BackgroundInferior conjunctivochalasis is common, but is rarely severe enough to require conjunctival excision. This report describes a patient with severe conjunctivochalasis who was subsequently diagnosed with Ehlers Danlos Syndrome, Classic Type.Case presentationA patient suffering from foreign body sensation, frequent blinking and bilateral inferior conjunctivochalasis was referred and treated by topical ocular lubrication. However, no improvement was observed prompting potential excision of conjunctivochalasis. Following patient consultation and clinical diagnosis including hypermobile joints and skin elasticity, poor wound healing and wide scar morphology, Ehlers-Danlos syndrome was confirmed in the patient.ConclusionThis case highlights the need for direct patient questioning and provides the first reported association between conjunctiovochalasis and Ehlers-Danlos syndrome.

United Kingdom national cataract training survey

&NA; A nationwide postal survey of all consultant ophthalmologists in the United Kingdom was conducted to determine attitudes and techniques of cataract surgery trainers, identify trainer‐related factors that determine surgical opportunity, and ascertain whether trainers had received adequate training in how to teach surgery. The response rate was 43% (410/950). Seventy‐nine percent of respondents were men; 46% worked in a university teaching hospital (UTH). University teaching hospital consultants provided more surgical opportunities to their trainees (P<.001). Surgical opportunity was directly correlated with number of vitreoretinal surgeons in the department independent of UTH status (P<.001). Eighty‐three percent of trainers had received no formal training in how to teach surgery; only 12% of these expressed a desire to undertake such training. Further research is required to determine optimal methods for delivery of ophthalmic surgical training. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

The visualisation of vitreous using surface modified poly(lactic-co-glycolic acid) microparticles

Aims To demonstrate the potential use of in vitro poly(lactic-co-glycolic acid) (PLGA) microparticles in comparison with triamcinolone suspension to aid visualisation of vitreous during anterior and posterior vitrectomy. Methods PLGA microparticles (diameter 10–60 μm) were fabricated using single and/or double emulsion technique(s) and used untreated or following the surface adsorption of a protein (transglutaminase). Particle size, shape, morphology and surface topography were assessed using scanning electron microscopy (SEM) and compared with a standard triamcinolone suspension. The efficacy of these microparticles to enhance visualisation of vitreous against the triamcinolone suspension was assessed using an in vitro set-up exploiting porcine vitreous. Results Unmodified PLGA microparticles failed to adequately adhere to porcine vitreous and were readily washed out by irrigation. In contrast, modified transglutaminase-coated PLGA microparticles demonstrated a significant improvement in adhesiveness and were comparable to a triamcinolone suspension in their ability to enhance the visualisation of vitreous. This adhesive behaviour also demonstrated selectivity by not binding to the corneal endothelium. Conclusion The use of transglutaminase-modified biodegradable PLGA microparticles represents a novel method of visualising vitreous and aiding vitrectomy. This method may provide a distinct alternative for the visualisation of vitreous whilst eliminating the pharmacological effects of triamcinolone acetonide suspension.

Silicone oil-induced corneal perforation following complex retinal detachment.

PURPOSE To report a case of silicone oil-induced corneal perforation following complex retinal detachment surgery. METHODS Case report. RESULTS Two months following a second retinal detachment repair, the patient presented to eye casualty with a corneal perforation secondary to silicone oil keratopathy. CONCLUSION The pathophysiology of silicone oil-related perforation is not clearly understood. Poor corneal nutrition due to the presence of oil may be an important contributory factor. Close monitoring of patients for early signs of silicone oil keratopathy could preempt perforation.

Use of Thermoreversible Hydrogels in Corneal Wound Repair

Corneal infection, inflammation and injury can result in scarring and loss of transparency of the cornea, which accounts for one to two million cases of monocular blindness worldwide. Modulating and promoting wound healing of the cornea has proved to be a major challenge. The amniotic membrane is currently used as a biological bandage to achieve this; however, many limitations have been shown to exist with this technique. Hydrogels are large polymeric networks that have a high fluid content. Such polymers can be manipulated to switch between liquid and solid states depending on light, temperature and ionic changes and can be either biodegradable or nonbiodegradable. Thermosensitive hydrogels can be manipulated to form gels at body temperature and may hold potential as synthetic scaffolds for ocular surface reconstruction, wound healing and ophthalmic drug delivery.