Grant R. Snibson

Management of alkali burns : an 11-year retrospective review.

OBJECTIVE To review the spectrum of patients with alkali burns admitted over an 11-year period and to assess the clinical outcomes after the introduction of a standard alkali burn treatment protocol. DESIGN Retrospective nonrandomized comparative study. PATIENTS AND INTERVENTIONS A total of 121 patient records with alkali burns (n = 177 eyes) admitted to a tertiary hospital between 1987 and 1998 were reviewed. Eyes treated with a standard alkali burn treatment protocol, which included intensive topical steroids, ascorbate, citrate, and antibiotics, were compared with eyes treated by conservative management with antibiotics, and a short course of steroids. MAIN OUTCOME MEASURES Time to corneal reepithelialization, final best-corrected visual acuity, and time to visual recovery, length of hospital stay, and complications were analyzed. RESULTS The standard protocol tended to delay corneal reepithelialization by one day (P: = not significant) in eyes with grade 1 burns (n = 76) and by 2 days (P: = 0.04) in grade 2 burns (n = 52), with no difference in final visual outcome. There were 37 eyes with grade 3 burns. Those treated with the standard protocol showed a trend toward more rapid corneal reepithelialization. Twenty-seven of 29 (93%) eyes with grade 3 injuries achieved a final best-corrected visual acuity of 20/40 or better compared with 3 of 6 (50%) eyes not treated according to the standard protocol (P: = 0.02). Eyes with grade 4 burns (n = 12), whether treated with the standard protocol or not, required 10 to 12 weeks for corneal reepithelialization. There was no statistically significant difference in final visual acuity. CONCLUSIONS On the basis of our findings, a number of recommendations can be made for the management of alkali injuries. Patients with a grade 1 or 2 injury do not require routine admission and do not benefit from the use of intensive treatment with ascorbate and citrate. A trend toward more rapid healing and a better final visual outcome were apparent in grade 3 burns, but our standard protocol made no difference in grade 4 burns.

Late Recurrences and the Necessity for Long-term Follow-up in Corneal and Conjunctival Intraepithelial Neoplasia

PURPOSE The purpose of the study was to elucidate the natural history of corneal-conjunctival intraepithelial neoplasia (CIN) and suggest treatment and follow-up guidelines. METHODS The records of all histologically proven cases of CIN at the Royal Victorian Eye and Ear Hospital between 1979 and 1994 were reviewed. RESULTS Seventy-nine eyes of 76 patients had a pathologic diagnosis of CIN and were observed for up to 15 years. The lesion recurred in 31 eyes (39%) overall. There was no statistical difference shown in the likelihood of recurrence based on histologic classification. Complete excision was attempted in each case. In 18 eyes, dysplastic cells were evident at the excision margin. Ten (56%) of these tumors recurred, compared to a 33% recurrence rate in completely excised lesions. The time to the first recurrence ranged from 33.0 days to 11.5 years between the first and second surgeries, with 11 lesions recurring after more than 4 years. Incompletely excised lesions reappeared more rapidly (average, 2.5 years) than did those with clear surgical margins (average, 3.8 years). Seven cases progressed to invasive squamous cell carcinoma and four cases led to blindness or removal of the eye. CONCLUSIONS This study suggests that excision margin at the time of surgery is the most important factor in predicting recurrence. The slow growth of the recurrent lesions combined with the ever-present malignant potential leads the authors to suggest that all patients with a history of CIN warrant annual follow-up for the remainder of their lives.

Corneal replacement using a synthetic hydrogel cornea, AlphaCor: device, preliminary outcomes and complications.

AbstractPurpose Clinical assessment of outcome of corneal replacement with a synthetic cornea, AlphaCor™, in patients considered at too high risk for conventional penetrating keratoplasty with donor tissue to be successful, but excluding indications such as end-stage dry eye that might be suited to traditional prosthokeratoplasty.Methods All patients in the multicentre clinical trial were managed according to an approved protocol, with Ethics Committee approval in each centre. Preoperative visual acuity ranged from perception of light (PL) to 6/60 (20/200). Implantation was by means of an intralamellar technique, with a conjunctival flap in most cases. Tissues anterior to the optic were removed as a secondary procedure.Results Up to 30 November 2001, 40 AlphaCor™ devices had been implanted in 38 patients, of mean age 60 years. Follow-up ranged from 0.5 months to 3 years. There had been one extrusion (2.5%) and four cases (10%) where a device had been removed due to melt-related complications. All five of these cases received a donor corneal graft after the device was removed, with these grafts remaining anatomically satisfactory and epithelialised to date. Corneal melts in AlphaCor™ recipients were found to be strongly associated with a history of ocular herpes simplex infection. Two further devices (5%) were removed owing to reduced optic clarity after presumed drug-related deposition, and have been successfully replaced with second devices. Mean preoperative best-corrected visual acuity was hand movements. Visual acuities after surgery ranged from PL to 6/6−2 (20/20−2).Conclusions Early results suggest that the AlphaCor™, previously known as the Chirila keratoprosthesis (Chirila KPro), has a low incidence of the complications traditionally associated with keratoprostheses and can be effective in restoring vision in patients considered untreatable by conventional corneal transplantation. Importantly, the device can be replaced with a donor graft in the event of development of a significant complication. A history of ocular herpes simplex is a contraindication to AlphaCor™ implantation. Ongoing monitoring of clinical outcomes in all patients will allow the indications for AlphaCor™, as opposed to donor grafts, to be determined.

Collagen cross-linking: a new treatment paradigm in corneal disease - a review.

The last 2 years has seen a marked increase in the prominence of corneal collagen cross‐linking as a treatment strategy for progressive keratoconus. This interest has arisen from a body of laboratory evidence documenting the biomechanical and cellular changes induced by cross‐linking. The findings of this research provide a plausible rationale for its use in keratoconus to retard the progression of this common disease. The rapidly growing number of clinical reports suggests, not only a consistent stabilizing effect of cross‐linking, but that a variable improvement in corneal shape and visual function may also occur in some patients. However, the marked variation in the clinical course of keratoconus, together with the challenges of accurately evaluating refractive error, visual acuity and even corneal shape in this condition, demands further evidence from randomized controlled clinical trials. The aim of this review is to summarize the theoretical basis and risks of corneal collagen cross‐linking, along with the available evidence for its use in keratoconus and other corneal disease states.

Current status of corneal collagen cross‐linking for keratoconus: a review

Over the past decade, corneal collagen cross-linking has become commonplace as a treatment option for individuals with progressive keratoconus. This is based on laboratory data suggesting that cross-linking using riboflavin and ultraviolet-A irradiation increases collagen diameter and the biomechanical strength of the treated cornea. Case series and limited randomised controlled trials support these findings with data demonstrating that cross-linking slows and possibly halts the progression of keratoconus. In some patients cross-linking results in an improvement in maximum corneal curvature, visual acuity, spherical equivalent and higher-order aberrations. The number of reported complications is small. More recently, variations in the treatment protocol have been described, although they have not yet been subject to comparative studies. While the published data indicate cross-linking is effective in modifying the natural history of keratoconus, the long-term impact of this treatment is still unknown. This paper reviews the theoretical basis, pre-clinical research and clinical results of corneal collagen cross-linking in keratoconus.Over the past decade, corneal collagen cross‐linking has become commonplace as a treatment option for individuals with progressive keratoconus. This is based on laboratory data suggesting that cross‐linking using riboflavin and ultraviolet‐A irradiation increases collagen diameter and the biomechanical strength of the treated cornea. Case series and limited randomised controlled trials support these findings with data demonstrating that cross‐linking slows and possibly halts the progression of keratoconus. In some patients cross‐linking results in an improvement in maximum corneal curvature, visual acuity, spherical equivalent and higher‐order aberrations. The number of reported complications is small. More recently, variations in the treatment protocol have been described, although they have not yet been subject to comparative studies. While the published data indicate cross‐linking is effective in modifying the natural history of keratoconus, the long‐term impact of this treatment is still unknown. This paper reviews the theoretical basis, pre‐clinical research and clinical results of corneal collagen cross‐linking in keratoconus.

AlphaCor™ cases : comparative outcomes

Purpose To describe clinical outcomes after a novel type of corneal surgery, implantation of an artificial cornea, AlphaCor™, and to evaluate outcomes in comparison with alternative keratoprostheses and high-risk grafts. Methods Case reports and data from a noncontrolled clinical trial and a literature review. Results The probability of AlphaCor retention to 1 year is 80%. Postoperative best corrected visual acuity ranges from Perception Light to 20/30. The most significant complications are stromal melts and optic depositions, for both of which the main risk factors have been identified. Complications can be managed without loss of the eye. Conclusion Results from the clinical trial period have helped to determine the indications and risk factors for AlphaCor surgery and to refine surgical techniques. Continued monitoring of outcomes as the series increases will allow a more accurate determination of comparative outcomes. The series provides preliminary evidence that AlphaCor may have a lower incidence of complications than traditional keratoprostheses and may prove to be preferable to a donor graft in high-risk cases.

Outcomes of implantation of an artificial cornea, AlphaCor: effects of prior ocular herpes simplex infection.

Purpose. To review outcomes of AlphaCor artificial cornea implantation in patients with and without a history of ocular herpes simplex virus (HSV) and to determine whether herpetic eye disease is an indication for AlphaCor surgery. Methods. Outcomes of the initial 40 implantations were reviewed and stratified by the presence of a history of ocular disease caused by HSV. Outcomes measures (complications, visual acuity gained) were compared. Results. Eight of the 40 AlphaCor implantations (20%) were in patients with a history of ocular HSV. Six of these eight patients (75%) developed melt-related complications after AlphaCor insertion. Half of the affected patients required removal of the AlphaCor and replacement with a donor corneal graft to restore ocular integrity. In comparison, only six of the 32 (18.8%) patients without HSV developed a melt after AlphaCor insertion. Patients with HSV with devices in situ exhibited a mean loss of 0.3 line of best-corrected visual acuity compared with the preoperative visual acuity, whereas patients without HSV exhibited a mean gain of 1.4 lines of best-corrected visual acuity. Conclusions. The extensive lamellar corneal surgery involved in AlphaCor implantation may precipitate reactivation of latent HSV such that reactivation and resultant inflammation reduce device biointegration and facilitate melting of corneal stromal tissue anterior to the device. Although there may be some benefit from systemic antiviral medication, the current series is not large enough to demonstrate such a benefit, and melting can occur despite medication. The statistically significant difference in outcomes between recipients of AlphaCor with and without HSV is evidence that a history of HSV should be an exclusion factor for AlphaCor surgery.

Amniotic membrane grafting in the surgical management of primary pterygium

Background: To evaluate the efficacy of amniotic membrane transplantation in primary pterygium surgery.

Acanthamoeba keratitis and contact lens wear

Acanthamoeba keratitis is a rare but serious complication of contact lens wear that may cause severe visual loss. The clinical picture is usually characterised by severe pain, sometimes disproportionate to the signs, with an early superficial keratitis that is often misdiagnosed as herpes simplex virus (HSV) keratitis. Advanced stages of the infection are usually characterised by central corneal epithelial loss and marked stromal opacification with subsequent loss of vision. In this paper, six cases of contact lens‐related Acanthamoeba keratitis that occurred in Australia and New Zealand over a three‐year period are described. Three of the patients were disposable soft lens wearers, two were hybrid lens wearers and one was a rigid gas permeable lens wearer. For all six cases, the risk factors for Acanthamoeba keratitis were contact lens wear with inappropriate or ineffective lens maintenance and exposure of the contact lenses to tap or other sources of water. All six patients responded well to medical therapy that involved topical use of appropriate therapeutic agents, most commonly polyhexamethylene biguanide and propamidine isethionate, although two of the patients also subsequently underwent deep lamellar keratoplasty due to residual corneal surface irregularity and stromal scarring. Despite the significant advances that have been made in the medical therapy of Acanthamoeba keratitis over the past 10 years, prevention remains the best treatment and patients who wear contact lenses must be thoroughly educated about the proper use and care of the lenses. In particular, exposure of the contact lenses to tap water or other sources of water should be avoided.

A comparison of different depth ablations in the treatment of painful bullous keratopathy with phototherapeutic keratectomy.

AIM To study the efficacy of phototherapeutic keratectomy (PTK) for pain relief for patients with painful bullous keratopathy and poor visual potential. METHODS Patients with painful bullous keratopathy and poor visual potential were treated with superficial PTK (8–25 μm), intermediate (50–100 μm) or deep PTK (25% stromal thickness) using the Nidek EC5000 excimer laser after manual epithelial debridement. Follow up ranged from 1 to 24 months (mean 6.5 months). Outcome measures included symptomatic relief and need for further treatment. RESULTS In the superficial PTK group five of eight (62%) patients improved symptomatically after treatment. The three (38%) who did not improve went on to have penetrating keratoplasty for pain relief. In the intermediate depth group only two of five (40%) patients had symptom alleviation. The three others (60%) required further procedures. 20 of 24 (83%) patients treated with deep PTK had significant or total alleviation of symptoms. Of these, one developed acute anterior uveitis 9 months after PTK and two required botulinum ptosis for persistent corneal epithelial defects, one of whom had three consecutive episodes of microbial keratitis. Three of 24 suffered occasional discomfort and one patient required a penetrating keratoplasty for continued pain. CONCLUSION PTK can be a useful therapeutic measure in painful bullous keratopathy with poor visual potential. Deep PTK appears to be more successful in pain management than superficial treatment.