Cataract Surgery in Patients with Keratoconus: Pearls and Pitfalls.

BACKGROUND: Keratoconus (KC) is a common ectatic disorder resulting in progressive corneal thinning and irregular astigmatism. It has been observed that patients affected by KC are more likely to develop lens opacities earlier compared to non-keratoconic patients. OBJECTIVE: Intraocular lens (IOL) selection and refractive outcome prediction are among a number of factors that can make cataract surgery in keratoconic patients challenging. Accurate biometry is often difficult to obtain due to unreliable K measurements and lack of dedicated biometric formulae. The use of toric IOLs has also been investigated. CONCLUSIONS: Determining the stage of KC, pre-operative patient counselling and the preferred method of refractive correction are all crucial to obtain successful postoperative outcomes and good patient satisfaction. The use of toric IOLs can achieve good results only in selected low-grade keratoconic eyes.

A mouse model of lamellar intrastromal femtosecond laser keratotomy: ultra-structural, inflammatory, and wound healing responses.

PURPOSE: The availability of knockout mouse species provide a highly versatile platform for critically examining the corneal wound healing response. We aimed to develop and characterize the wound healing response in a mouse model of intrastromal femtosecond laser (FSL) keratotomy. METHODS: An intrastromal lamellar dissection using a Visumax FSL was performed on 16 wild type mice (C57BL6) . The energy level was optimized at 150nJ. The FSL was programmed to perform a lamellar dissection at 50 µM depth without sidecut. The flap was not lifted. Fellow eyes were used as controls. Slit lamp photography and confocal microscopy were performed immediately before the mice were sacrificed 4 h, 1, 3, and 7 days post surgery. Corneas were harvested for immunocytochemistry, transmission electron microscopy (TEM) and light microscopy (LM). RESULTS: Confocal microscopy showed an absence of keratocytes in the area immediately surrounding the dissection plane. The dissection plane and individual FSL plasma cavitation bubbles were clearly evident on TEM. There was evidence of Keratocyte cell death along the laser resection plane on TEM. LM revealed the dissection plane at a 20 µM depth, although not all epithelial cell layers were intact. Staining for monocytes using antibodies for CD11b (cluster of differentiation 11b) showed early migration at the peripheries at 4 h that increased at 24 h and became more central in treated corneas (p<0.001). Apoptotic cells were evident on TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay in the immediate ablation zone and were significantly raised at 4 and 24 h (p<0.001). Ki67 (Kiel 67 protein) positive proliferating keratocytes are evident at 3 days and increased significantly by 7 days (p<0.001). Minimal fibroblast (cluster of differentiation 90, CD90) transformation was seen at 1 week. No myofibroblasts were detected. DISCUSSION: We have demonstrated that FSL lamellar cuts can be effectively performed on mice and that this model exhibits typical signs of the corneal wound healing response. This model could provide a ubiquitous platform in which to study corneal wound healing responses in both wild type and knockout mice species. The ability to create such a lamellar pocket may be utilizzd for intrastromal drug delivery.

Intravitreal triamcinalone acetonide for refractory uveitic cystoid macular oedema: longterm management and outcome.

PURPOSE: To establish the role of intravitreal triamcinalone acetonide (TA) in the long term management of refractory uveitic cystoid macular oedema (CMO) and to determine the long term visual outcome in these patients. METHOD: This is a retrospective observational case series. All patients had resistant CMO and active inflammation. The primary outcome measure was complete resolution of CMO on ocular coherence tomography. Visual acuity and intraocular pressure were also monitored. Twelve eyes of twelve patients received 2 (n = 10) to 4 (n = 2) mg of intravitreal TA. All had previously been unresponsive to orbital floor steroids. Fluorescein angiography was performed where indicated. RESULTS: There was complete resolution of CMO in all patients. Nine patients had improvement in acuity at there final follow up (mean follow up 40.5 months). Seven had improved by 2 lines (58%). In 3 patients there was no visual improvement. These 3 failed to respond to re-treatment. Five other patients were re-treated because of recurring CMO and deteriorating VA (median time to re-treatment 4 mths). The mean number of re-treatments for this group with orbital floor TA was three. 41.6% of patients developed ocular hypertension (33.8 mhg mean). One required a trabeculectomy. CONCLUSIONS: 2 mg of intravitreal TA is effective even in cases of resistant uveitic CMO. Although re-treatment is often required, the initial response to treatment can be maintained by subsequent orbital floor steroid injections.