Molecular screening of the CYP4V2 gene in Bietti crystalline dystrophy that is associated with choroidal neovascularization.

PURPOSE: Bietti crystalline dystrophy (BCD) is an autosomal recessive disease characterized by intraretinal deposits of multiple small crystals, with or without associated crystal deposits in the cornea. The disease is caused by mutation in the cytochrome p450, family 4, subfamily v, polypeptide 2 (CYP4V2) gene. Choroidal neovascularization (CNV) is a rare event in BCD. We report two cases of BCD associated with CNV. CYP4V2 and exon 5 of tissue inhibitor of metalloproteinase 3 (TIMP3) were screened in both cases. A patient with BCD, but without CNV, was also screened to identify pathogenic variations. METHODS: Three BCD families of Asian Indian origin were recruited after a comprehensive ophthalmic examination. Genomic DNA was isolated from blood leukocytes, and coding exons and flanking introns of CYP4V2 and exon 5 of TIMP3 were amplified via polymerase chain reaction (PCR) and were sequenced. Family segregation, control screening, and bioinformatics tools were used to assess the pathogenicity of the novel variations. RESULTS: Of the three BCD patients, two had parafoveal CNV. The patient with BCD, but without CNV had novel single base-pair duplication (c.1062_1063dupA). This mutation results in a structurally defective and unstable protein with impaired protein function. Four novel benign variations (three in exons and one in an intron) were observed in the cohort. Screening of exon 5 of TIMP3 did not reveal any variation in these families. CONCLUSIONS: A novel mutation was found in a patient with BCD but without CNV, while patients with BCD and CNV did not show any pathogenic variation. The modifier role of TIMP3 in the pathogenesis of CNV in BCD was partly ruled out, as no variation was observed in exon 5 of the gene. A larger BCD cohort with CNV needs to be studied and screened to understand the genetics of CNV in BCD.

Foveal atrophy and macular hole formation following intravitreal ranibizumab with/without photodynamic therapy for choroidal neovascularization secondary to age-related macular degeneration.

BACKGROUND: To report the occurrence of foveal atrophy and macular hole formation following intravitreal ranibizumab with or without photodynamic therapy for choroidal neovascularization caused by age-related macular degeneration. METHODS: This was a retrospective, interventional case series, in which 78 eyes of 76 patients were treated for wet age-related macular degeneration between February 2007 and August 2007. Of these, three eyes developed foveal atrophy following treatment. Two eyes underwent combination photodynamic therapy and intravitreal ranibizumab, and one eye underwent intravitreal ranibizumab alone. One of the two eyes that underwent combination therapy progressed to develop a macular hole. RESULTS: On the first follow-up visit, all three eyes showed thinning of the fovea on optical coherence tomography. Subsequently, treatment was continued with repeat intravitreal ranibizumab injections. At the last follow-up, although choroidal neovascularization regressed in all eyes, extensive foveal atrophy developed in two eyes with macular hole formation in one eye. CONCLUSION: The possibility of foveal atrophy and macular hole formation must be borne in mind before initiating ranibizumab in combination with or without photodynamic therapy. However, larger studies with longer follow-up are required to understand such adverse effects better.

Lysyl oxidase activity in the ocular tissues and the role of LOX in proliferative diabetic retinopathy and rhegmatogenous retinal detachment.

PURPOSE: Lysyl oxidase (LOX) cross-links the side chain of collagen and elastin and thereby contributes to extracellular matrix (ECM) integrity. ECM remodeling is seen in various ocular diseases. Until now, there have been no reports on the LOX enzyme's activity in ocular tissues. The purpose of this study was to estimate LOX activity and expression in human donor ocular tissues and to measure the specific activity of LOX in the vitreous of proliferative diabetic retinopathy (PDR) and rhegmatogenous retinal detachment (RRD). METHOD: Human donor eyeballs obtained from an eye bank were used to study tissue distribution of LOX. Human vitreous specimens were obtained during vitreoretinal surgery from PDR (n = 16) and RRD (n = 10). LOX activity was estimated by N-acetyl-3,7-dihydroxyphenoxazine assay, immunohistochemistry, and real-time polymerase chain reaction (RT-PCR). Matrix metalloprotease (MMP)-2 and -9 were quantified in the vitreous by sandwich enzyme-linked immunosorbent assay (ELISA). RESULTS: The specific activity of LOX in ocular tissues was on the order of vitreous, iris ciliary body, lens, choroid RPE, and retina, which were comparable by mRNA expression and immunolocalization. The vitreous level of LOX activity decreased significantly in PDR and RRD, with an increase in total MMP-2 and -9 levels compared with normal donor vitreous. CONCLUSIONS: LOX activity showed a statistically significant decrease in the vitreous of PDR and RRD relative to control specimens. This effect can contribute to the inadequate collagen cross-linking that causes the ECM changes that occur in these diseases.

Trace elements iron, copper and zinc in vitreous of patients with various vitreoretinal diseases.

PURPOSE: To measure the concentrations of iron, copper and zinc in human vitreous and to interpret their levels with various vitreoretinal diseases like proliferative diabetic retinopathy, retinal detachment, intraocular foreign body, Eales' disease and macular hole. METHODS: Undiluted vitreous fluid collected during pars plana vitrectomy was used to measure trace elements using an atomic absorption spectrophotometer. RESULTS: The level of vitreous iron increased threefold in Eales' disease (1.85 +/- 0.36 pg/ml), 2.5-fold in proliferative diabetic retinopathy (1.534 +/- 0.17 pg/ml) and 2.3-fold in eyes with intraocular foreign body (1.341 +/- 0.25 pg/ml) when compared with macular hole (0.588 +/- 0.16 pg/ml). This was statistically significant (P < 0.05). Zinc was found to be low in Eales' disease (0.57 +/- 0.22 pg/ ml) when compared with other groups, though the difference was not statistically significant. CONCLUSION: The increased level of iron with decreased zinc content in Eales' disease confirms the earlier reported oxidative stress mechanism for the disease. In proliferative diabetic retinopathy and intraocular foreign body the level of iron increases. This is undesirable as iron can augment glycoxidation, which can lead to increased susceptibility to oxidative damage, in turn causing vitreous liquefaction, posterior vitreous detachment and ultimately retinal detachment and vision loss.