Acute Chemical Eye Injury and Limbal Stem Cell Deficiency-A Prospective Study in the United Kingdom.

PURPOSE: To analyze the incidence, nature, outcomes, and complications of acute chemical eye injuries, including the incidence of limbal stem cell deficiency (LSCD) and to compare the 2 main classifications for ocular chemical injuries: Roper-Hall (RH) and Dua. METHODS: This is a prospective, consecutive, interventional single-center study between April and October 2009 of all new patients with acute chemical eye injury presenting to the Royal Victoria Infirmary eye emergency department (EED). RESULTS: Of 11,683 patients who attended the EED, 98 patients (110 eyes) presented with acute chemical eye injury (60% male). This represents an estimated annual incidence of 5.6 new cases per 100,000 population. Mean age was 36.5 years (1-78; SD 17.1 years), including 7 children (age <10 years). Fifty-one patients (52%) had work-related injuries. The most common chemical agent was alkali (78%). All 4 RH grade IV cases were unilateral, assault with ammonia, and required early amniotic membrane transplantation as per the protocol, but despite full treatment, they developed total LSCD in the affected eye. CONCLUSIONS: Acute chemical eye injuries are rare. Male patients in the working age group are more prone to work-related chemical injuries, whereas young children tend to have domestic injuries. Grade I, II, and III RH and Dua chemical injuries had a very good prognosis with topical treatment only, whereas RH grade IV (Dua grade IV-VI), mainly assaults with ammonia, progressed to total/severe LSCD despite appropriate management including early amniotic membrane transplantation. The Dua classification includes conjunctival involvement, having a greater value in predicting the final clinical outcome when grading chemical eye injuries.

Measuring the benefit of 4 years of intravitreal ranibizumab treatment for neovascular age-related macular degeneration.

AIM: To analyse the benefit of intravitreal ranibizumab over 4 years for patients with neovascular age-related macular degeneration (AMD). METHODS: A retrospective case note review of all patients who started treatment between August 2007 and September 2009 in our unit, minimum follow-up 2 years, maximum 4 years. The main outcome measures were: numbers of patients with different levels of vision, changes in visual acuity, number of treatments and numbers remaining under follow-up. RESULTS: 1086 eyes of 1017 patients received treatment. Numbers of patients remaining under follow-up were 892/1017 (87.71%) at 12 months, 730/1017 (71.78%) at 24 months, 468/730 (64.11%) at 36 months and 110/217 (50.69%) at 48 months. The main reasons for patients no longer being under follow-up were the consequences of old age or transfer of care. 50% of patients had 6/18 or better over 4 years. Patients received on average 5.79 ± 2.53, 9.15 ± 3.79, 11.22 ± 4.92 and 13.7 ± 7.84 injections by 12, 24, 36 and 48 months, respectively. CONCLUSIONS: We suggest that the numbers of patients with a particular level of vision may best reflect the actual benefit of AMD treatment provided by a service. Long-term follow-up is required as only 72/730 (10%) had been discharged at 36 months, half of whom had good vision of greater than 60 letters. 83% and 65% of patients needed treatment in the third and fourth year. Follow-up may be for the rest of the patients' life or at some point they may no longer be well enough to attend.

The relationship of Central Corneal Thickness (CCT) to Thinnest Central Cornea (TCC) in healthy adults.

PURPOSE: The aim of the study was to precisely quantify the relationship between the central corneal points, namely the pupillary centre and the thinnest point in the central cornea, in terms of their thickness and location in healthy adults. METHODS: 120 eyes of 60 healthy adult volunteers underwent pachymetry with a Scheimpflug imaging system (Pentacam). The thickness at the pupillary centre (Central Corneal Thickness, CCT) and the thickness at the Thinnest Central Corneal (TCC) point were measured. One eye of each patient was used to analyse the mean difference between CCT and TCC. Unpaired t-test (one tailed) was used to test significance and 95% confidence limits were used. The precise location of the TCC in relation to the corneal apex was measured using vector algebraic and trigonometric calculations. RESULTS: The mean CCT was 520+/-33microm and the TCC was 515+/-36microm. The difference between CCT and TCC was found to be 5.57microm (0-15.9microm, 95% CI; P=0.1909). The TCC location was inferotemporal to the corneal apex in 58/60 (96.7%) of the right eyes and in 49/60 (81.7%) of the left eyes. The average vector location of TCC of both eyes was inferotemporal. This coordinate was found to lie 0.62mm (right eye) and 0.79mm (left eye) from the corneal apex subtending and angle of 45.5 degrees (right eye) and -10.9 degrees (left eye) from the horizontal. CONCLUSION: The study has identified the parameters of TCC and its relationship to CCT in terms of the location and thickness. For clinical usage, they can be interchangeable as there is no significant difference between the two. The consistency in the (inferotemporal) location of the TCC merits further research in this regard to the development of corneal ectasia.

A histopathologic study of orbital implant vascularization.

PURPOSE: To histopathologically assess the extent and pattern of vascularization of explanted porous polyethylene (PP) and hyrdoxyapatite (HA) orbital implants. To compare the vascularization in PP implants harvested after enucleation versus after evisceration. METHODS: This is a comparative case series of six orbital implants explanted between 11 months and 5 years and 4 months post implantation. The implants were subjected to histopathological examination with various stains, after complete decalcification. RESULTS: There were 2 post evisceration, 3 post enucleation and 1 secondary implant. The size of the implants varied from 18 to 23 mm diameter. The reason for explantation was exposure in all the 6 cases with additional infection in 2 cases. Histopathology revealed complete vascularization up to the core of the implant in all the cases. There was evidence of chronic inflammation within all the explanted specimens. Acute inflammation was present at the site of exposure in four of the implants. Three of these implants had additional evidence of necrosis. Two cases with clinically evident infection had Gram positive cocci within the implant. Foreign-body type giant-cells, melanophages and haemosiderin laden macrophages were also observed. Eviscerated specimens showed scleral remodelling and thickening. CONCLUSION: All the implants were vascularized up to the core. There was histologic evidence of chronic inflammation in all the explanted implants possibly indicating the foreign nature of the implant material. The sclera did not impede vascularization of the implants in eviscerated specimens. We found no difference in the degree of vascularization of the implant in enucleated versus eviscerated implants.

The use of AlloDerm in the reconstruction of full-thickness eyelid defects.

PURPOSE: To demonstrate the potential for the use of AlloDerm as a posterior lamellar graft in the reconstruction of full-thickness lid defects. METHOD: In our case series, we evaluated the surgical outcome of three consecutive patients, two with an upper eyelid defect and one with a lower eyelid defect who underwent lid reconstruction using AlloDerm grafts. RESULTS: AlloDerm was readily taken up into the wound defect, with complete coverage of its bulbar surface by conjunctiva. In all the cases, the cornea was not affected by its contact to the AlloDerm. A mucocutaneous junction formed over the margin of the AlloDerm graft with good cosmesis. CONCLUSION: AlloDerm has the potential to act as an effective posterior lamellar substitute in situations where there is an adequate amount of skin muscle cover available to drape over it. It is rigid enough to replace tarsus and its structure behaves as a scaffold allowing conjunctiva to readily grow over it.

Lateral cantholysis for cataract surgery.

A patient with narrow palpebral aperture who required an elaborate lateral cantholysis prior to uncomplicated phacoemulsification surgery is described. Surgery was followed by a lateral tarsal strip procedure to reattach the lower lid.