Topical interferon alpha 2b for corneal haze after excimer laser photorefractive keratectomy. The Melbourne Excimer Laser Group

Interferon Alpha 2a and 2b in Ophthalmology: A Review

Interferon alpha (IFN-α) is a glycoprotein with antitumor, antiviral, and immunomodulatory activity, used widely in the treatment of viral infections (hepatitis B and C, condylomata acuminata, herpes zoster, etc.), hematological disorders (leukemia, multiple myeloma, T cell lymphoma, and essential thrombocythemia), and solid tumors (clear cell carcinoma in the metastatic stage, melanoma, hepatocellular carcinoma, and cervical neoplasia). Studies have proven the effectiveness of IFN-α in the treatment of ophthalmic disorders involving the anterior segment of the eye (conjunctival papilloma, squamous neoplasia, conjunctival mucosa-associated lymphoid tissue, Mooren's ulcer, and vernal keratoconjunctivitis) and the posterior segment of the eye (serpiginous choroidopathy, posterior uveitis, pseudophakic and diabetic cystoid macular edema, and proliferative diabetic retinopathy). The therapy with IFN-α remains a promising alternative in cases of a failing response to conventional therapy, helping to maintain or improve visual acuity, prevent vision loss, and ameliorate the prognosis of the patient. However, clinicians who decide to use IFN-α in their patients must be aware of general and ophthalmological side effects and inform their patients to undergo a systemic evaluation such as a physical examination, blood and serological tests, and a chest X-ray before the beginning of treatment. This review presents the current knowledge of the use of IFN-α, its efficacy, and properties in ophthalmological diseases, and thus may encourage clinicians to administer this drug as a treatment modality in ophthalmological diseases in the future.

Matrix metalloproteinase 14 overexpression reduces corneal scarring

Once a corneal scar develops, surgical management remains the only option for visual rehabilitation. Corneal transplantation is the definitive treatment for a corneal scar. In addition to the challenges posed by graft rejections and other postoperative complications, the lack of high-quality donor corneas can limit the benefits possible with keratoplasty. The purpose of our study was to evaluate a new therapeutic strategy for treating corneal scarring by targeting collagen deposition. We overexpressed a fibril collagenase (matrix metalloproteinase 14 (MMP14)) to prevent collagen deposition in the scar tissue. We demonstrated that a single and simple direct injection of recombinant adeno-associated virus-based vector expressing murine MMP14 can modulate gene expression of murine stromal keratocytes. This tool opens new possibilities with regard to treatment. In a mouse model of corneal full-thickness incision, we observed that MMP14 overexpression reduced corneal opacity and expression of the major genes involved in corneal scarring, especially type III collagen and α-smooth muscle actin. These results represent proof of concept that gene transfer of MMP14 can reduce scar formation, which could have therapeutic applications after corneal trauma.

Ocular side effects of anti-rheumatic medications: what a rheumatologist should know

Nearly every drug may cause changes to ocular tissues through a variety of mechanisms. Medication overdoses, drug-drug interactions but also chronic administration of medications at the recommended doses may lead to ocular toxicity. The ocular side effects, screening for eye toxicity and treatment guidelines for anti-inflammatory and immunosuppressive drugs commonly used by rheumatologists are reviewed herein.

Treatment of dense subepithelial corneal haze after laser-assisted subepithelial keratectomy

We report a case of dense and visually significant corneal haze after laser-assisted subepithelial keratectomy (LASEK). Visually significant corneal haze after LASEK can be successfully treated with manual debridement and intraoperative mitomycin-C.

Correlation between ultraviolet radiation level and the incidence of late-onset corneal haze after photorefractive keratectomy

PURPOSE

To investigate the correlation between environmental changes in ultraviolet (UV) radiation levels and the incidence of late-onset cornea haze (LOCH) after photorefractive keratectomy (PRK).

SETTING

SynsLaser Clinic, Tromsø, Norway.

METHODS

The study comprised 404 eyes that had myopic PRK and photoastigmatic refractive keratectomy from February 1996 through July 1998. The high latitude (70 degrees N) of the observation site provided "natural laboratory" conditions to look at the occurrence of LOCH with high and low UV-radiation levels, which occurred during summers and winters, respectively. The diagnostic criterion for LOCH was acute haze of grade > or =2 occurring between 4 and 12 months postoperatively.

RESULTS

The follow-up ranged from 12 to 41 months. Of the 314 eyes that met the inclusion criteria, 11 developed LOCH when the environmental UV-radiation level was high. No eye developed LOCH when the level was low. The correlation between a high level of environmental UV radiation and the occurrence of LOCH was statistically significant (P =.001).

CONCLUSION

Environments with high UV-radiation levels may increase the risk of LOCH after PRK in eyes with moderate to high myopia. Use of UV-protective eyewear should be encouraged during the first year after PRK.

The placebo effect

Placebos have been traditionally regarded as deceptive therapies and have not been understood in the broader context of social symbols and of interpersonal factors that surround the healing process itself. Although the power of inert substances to heal is well recognized, the placebo effect also influences the outcome of conventional therapies. The role of the placebo in modern medicine is poorly defined because of a lack of a common understanding of what the placebo effect is and because of the negative connotions associated with its use. The response rate to placebo varies by illness. The natural course of disease and patient or physician bias can be misinterpreted as a placebo response. In research, the placebo effect is therapeutic noise to be removed by placebo-controlled trials. Few studies are designed to measure the placebo response rate directly. Placebos are a reminder of how little is known about mind-body interaction. The placebo effect may be one of the most versatile and underused therapeutic tools at the disposal of physicians.

A randomized phase II trial of interferon-alpha2b versus 5-fluorouracil after trabeculectomy

PURPOSE

The aim of the present study was to investigate the safety and potential efficacy of subconjunctival interferon-alpha2b (IFN-alpha), either alone or in combination with 5-fluorouracil (5-FU), in reducing the risk of failure of glaucoma surgery

METHODS

A prospective, masked randomized phase II study was undertaken in which patients received three subconjunctival injections per week for 3-4 weeks postoperatively. Three treatments were compared: (i) IFN-alpha (1 x 10(6)IU per dose); (ii) 5-FU (5 mg per dose); and (iii) alternating IFN-alpha and 5-FU (BOTH). The primary outcome measures were: (i) rate of successful control of intra-ocular pressure without further surgery; and (ii) the incidence of side effects.

RESULTS

Fifty-seven patients undergoing glaucoma surgery with an increased risk of failure were evaluated, including 23 patients (40%) undergoing trabeculectomy combined with extracapsular cataract extraction as well as other conventional high-risk groups. With 53 patients (93%) completing 2 years follow up,there was no significant difference in success rates among the three groups. Intra-ocular pressure was controlled without further surgery in 79% of patients (95% confidence interval (CI): 61, 97%) receiving IFN-alpha, in 89% of patients (76, 100%) receiving 5-FU and in 89% of patients (76, 100% receiving BOTH. Side effects were similar among the three groups.

CONCLUSIONS

These results are consistent with a beneficial effect of IFN-alpha2b given either alone or in combination with 5-FU after glaucoma filtering surgery. However, the lack of a clear and substantial benefit over conventional anti-fibrotic therapy does not support the further clinical evaluation of these treatments.

Evaluation of Pentoxifylline in the Prevention of Haze after Photorefractive Keratectomy in the Rabbit

BACKGROUND

Pentoxifylline (PTX) is a methylxanthine derivative that, besides its hemorrheologic properties, possesses multiple physiologic effects at the cellular level. It has been used in keloid prevention due to its ability to inhibit the secretion of collagen and glycosaminoglycans from activated fibroblasts.

METHODS

Ten New Zealand White (NZW) rabbits underwent a -7.00 diopters, 6.0 mm diameter photorefractive keratectomy after laser ablation of the epithelium with a VISX 20/20 excimer laser. The bare stroma was stained with fresh 0.5% dichlorotriazinyl aminofluorescein (DTAF). The procedure was performed on both eyes, 4 days apart. One eye received 1% Pentoxifylline qid and the other balanced salt solution qid as a control for 4 weeks, starting the same day of surgery. Two masked observers graded the amount of haze at 2, 4, 6, and 8 weeks after surgery using slit-lamp biomicroscopy. Three rabbits were sacrificed at 2 and 4 weeks followed by two rabbits at 6 and 8 weeks. The area between the DTAF-stained collagen to the base of the epithelium was measured using a digital image analyzer.

RESULTS

There was no statistically significant difference in the amount of haze either by slit-lamp microscopy or by histological analysis between the pentoxifylline-treated eyes and the controls at any time interval (Student's t-test: 0.16 to 0.92)

CONCLUSION

Pentoxifylline did not seem to affect haze formation in a PRK rabbit model. As no signs of toxicity were observed, further studies might examine higher concentrations or dose frequencies.