Mitomycin: clinical applications in ophthalmic practice

Mitomycin (mitomycin C; MMC) is an antibiotic isolated from Streptomyces caespitosus. The drug is a bioreductive alkylating agent that undergoes metabolic reductive activation, and has various oxygen tension-dependent cytotoxic effects on cells, including the cross-linking of DNA. It is widely used systemically for the treatment of malignancies, and has gained popularity as topical adjunctive therapy in ocular and adnexal surgery over the past 2 decades. In ophthalmic medicine, it is principally used to inhibit the wound healing response and reduce scarring of surgically fashioned ostia. Hence, it has been used as adjunctive therapy in various ocular surgeries, such as glaucoma filtering surgeries, dacryocystorhinostomy, corneal refractive surgery and surgeries for ocular cicatrisation. In addition, it has been used as an adjunct in the surgical management of pterygia, ocular surface squamous neoplasia, primary acquired melanosis with atypia and conjunctival melanoma. In many of these surgeries and ophthalmic pathologies, MMC showed a significant beneficial effect.     

Hyperhomocysteinemia in patients with diabetes mellitus with and without diabetic retinopathy

OBJECTIVE: To evaluate the prevalence of hyperhomocysteinaemia in diabetic patients with no diabetic retinopathy (no DR), with non-proliferative diabetic retinopathy (NPDR) and with proliferative diabetic retinopathy (PDR). RESEARCH DESIGN AND METHODS: This prospective, case-control study, included 179 diabetic patients and 156 age-matched controls with no diabetes and no history of ocular disease, who were undergoing routine physical checkups. Plasma homocysteine levels of all study participants were measured using high-performance liquid chromatography (HPLC). Hyperhomocysteinaemia was defined when homocysteine levels were higher than 15 micromol/l. RESULTS: The mean plasma homocysteine level was 11.75+-0.24 in the control group,13.46+0.74 in the no DR group, 14.56 + 0.64 in the NPDR group and 15.86 + 1.34 in the PDR group. Mean homocysteine levels were significantly elevated in the NPDR and PDR groups compared to the control group(P = 0.001 and <0.0001, respectively). The prevalence of hyperhomocysteinaemia was also higher in the NPDR and PDR groups compared to the control group (P = 0.032 and 0.011, respectively). No statistically significant difference was found between the no DR and the control group. CONCLUSIONS: Our findings suggest that hyperhomocysteinaemia may be associated with diabetic retinopathy and partially explain the increased risk of microvascular angiopathy occurring in these patients.     

Comparison of corneal flap thickness between primary and fellow eyes using three microkeratomes

PURPOSE: To compare corneal flap thickness created in laser in situ keratomileusis (LASIK) in primary (right) and fellow (left) eyes (same blade for both eyes) using three microkeratomes. METHODS: The corneal thickness of 132 eyes (66 patients) was measured preoperatively and intraoperatively after flap creation. Corneal flap thickness was calculated by subtracting stromal bed thickness from total corneal thickness. Three microkeratomes were used: Nidek MK-2000, Bausch and Lomb Surgical Hansatome, and the Chiron Automated Corneal Shaper (ACS). Each patient had both corneas cut by one microkeratome and one blade at the same session. RESULTS: Mean corneal flap thickness created in primary eyes was 128.30 +/- 12.57 microm (range 105 to 147 microm) for the ACS (160-microm plate and 8.5-mm ring) and 122.96 +/- 13.30 microm (range 86 to 140 microm) for fellow eyes; Hansatome (160-microm plate and 8.5-mm ring): 141.16 +/- 20.11 microm (range 101 to 169 microm) in primary eyes and 120.95 +/- 26.95 microm (range 107 to 151 microm) in fellow eyes; Nidek (130-microm plate and 8.5-mm ring): 127.25 +/- 4.12 microm (range 116 to 134 microm) in primary eyes and 127.54 +/- 3.7 microm (range 119 to 134 microm) in fellow eyes. The corneal flap in the ACS and Hansatome microkeratomes was always thicker in the primary than the fellow eye, using the same blade for both eyes. No significant difference was found using the Nidek microkeratome. CONCLUSION: Corneal flap thickness tended to be thinner in fellow eyes than in primary eyes for the ACS and Hanstome microkeratomes. The Nidek microkeratome results were closer to specified corneal flap thickness than the ACS and Hanstome microkeratomes.     

C-reactive protein levels in normal tension glaucoma

PURPOSE: To determine C-reactive protein (CRP) levels in patients with normal tension glaucoma (NTG). METHODS: This study included 20 cases with NTG and 30 controls, with no history of ocular disease. Plasma CRP levels of all the study participants were determined using a highly sensitive CRP kit. RESULTS: Twenty cases (11 males, 9 females, mean age 69 +/- 5 years) with NTG and 30 age-matched controls (15 males, 15 females, mean age 68 +/- 6) were evaluated. Both groups had similar demographic parameters (age, sex, BMI). Plasma CRP levels were significantly higher in the NTG cases than in controls (median [range], 3.20 [0.17-8.4] mg/dL compared with 0.5 [0.1-3.2], P < 0.001). The mean plasma CRP level was significantly elevated in the NTG cases compared with the controls (3.21 +/- 0.6 mg/dL and 0.85 +/- 0.17 mg/dL, respectively, P < 0 0.01). CONCLUSION: Our findings suggest that higher CRP levels may be associated with NTG. It is possible that a vascular inflammatory process is involved in the etiology of this glaucoma.     

Periocular keratoacanthoma: can we always rely on the clinical diagnosis?

AIM: To present a series of patients with a clinical diagnosis of periocular keratoacanthoma and assess the incidence of histologically proven invasive squamous cell carcinoma (SCC). METHODS: This retrospective case series included all patients with periocular tumours seen in the authors' unit between 1996 and 2004, and who were initially diagnosed with keratoacanthoma based on the clinical presentation. RESULTS: Twelve patients (eight males, four females) were clinically diagnosed with keratoacanthoma. The final histological diagnosis revealed two cases (16.7%) of invasive SCC, and 10 cases (83.3%) of keratoacanthoma. The lower lid was most commonly involved in cases of keratoacanthoma (50.0%). Six patients (60.0%) underwent Mohs surgery, and four (40.0%) were treated with excision under frozen section control. There were no cases of recurrence during a mean follow up period of 21 (SD 13) months. CONCLUSION: Although the clinical presentation of periocular keratoacanthoma is usually characteristic, a significant percentage of patients will prove to have invasive SCC. Complete excision with margin control offers a definitive diagnosis, as well as tissue conservation and a low recurrence rate.     

Ophthalmic manifestations of multiple myeloma

PURPOSE: To describe ophthalmic manifestations in a series of patients with multiple myeloma (MM) and review the literature. DESIGN: Retrospective case series. METHODS: Review of all cases with ophthalmic manifestations of MM seen at the Department of Ophthalmology, Royal Adelaide Hospital, between 1987 and 2002. RESULTS: Of all patients with MM who were managed at the Royal Adelaide Hospital in the study period, only 8 were referred to the Ophthalmology Department with ophthalmic manifestations. Five males and 3 females with a mean age of 61.25 years (range 42-78) who exhibited ophthalmic manifestations were studied. Six patients (75%) had known MM at the time of their ophthalmic evaluation. Four patients (50%) had neuro-ophthalmic symptoms resulting in diplopia or visual disturbances. Three patients (37.5%) presented with orbital involvement and 1 (12.5%) with hyperviscosity retinopathy. Five patients (62.5%) died within 2 months of their ophthalmic presentation. CONCLUSION: Ophthalmic manifestations of MM are uncommon and diverse. They may appear at the initial presentation of the disease or occur late in the disease process. Awareness of the possible manifestations may lead to an earlier diagnosis and have a positive influence on the disease course.