Kazuki Ishibashi

Evaluation of the effect of aging on retinal nerve fiber layer thickness measured by optical coherence tomography.

Purpose: To evaluate the relationship between age and retinal nerve fiber layer (RNFL) thickness in normal subjects, as measured by optical coherence tomography (OCT). Methods: One hundred and forty-four normal subjects (144 eyes), ranging from 16 to 84 years of age, were enrolled in this cross-sectional study. The RNFL thickness was determined using OCT with three circle scans 3.4 mm in diameter. Results: The average RNFL thickness was inversely correlated with age (r = –0.348, p < 0.001). Analyzing the quadrants as a parameter, RNFL thickness in the superior, temporal and inferior quadrants also decreased with age. Using 30-degree segments, there were significant correlations between age and the RNFL thickness of temporal segments (7–11 o’clock). The average RNFL thickness had the highest correlation among all parameters (r = –0.348, p < 0.001). Regarding nasal quadrant thickness, RNFL ratios (average, superior, temporal and inferior RNFL thickness relative to the nasal quadrant thickness) were not significantly correlated with age. The refractive error did not affect RNFL thickness (r = 0.091, p = 0.276). Conclusion: Our study revealed that RNFL thickness, in particular in the temporal quadrant, measured by OCT significantly decreased with age. Age has to be taken into consideration when we compare RNFL thickness between normal and glaucomatous eyes.

The upregulation of angiogenic gene expression in cultured retinal pigment epithelial cells grown on type I collagen.

Purpose: Increases in matrix proteins, such as type I collagen and fibronectin, are observed with aging in the retinal pigment epithelium (RPE) basement membrane. However, little is known about altered gene expression profiles of RPE associated with increases in matrix proteins. We investigated changes in gene expression profiles of a human RPE cell line (ARPE-19) cultured on type I collagen. Methods: Visually confluent ARPE-19 cells were grown on either Matrigel (M group) or type I collagen (C group) without serum over 3 days. Total RNA was extracted and reverse transcribed. Gene expression profiles in both groups were compared using microarray analyses. Several angiogenic genes including integrin alpha V, integrin alpha 2, integrin beta 1, integrin beta 3, VEGF-A, VEGF-B, and VEGF-C were subjected to quantitative analyses using real-time PCR. Results: Out of 192 genes examined, angiogenesis-related genes (17.7%) and extracellular matrix–related genes (30.2%) were expressed highly (with more than 1.5-fold difference) in the C group when compared with the M group. In real-time PCR analyses, all VEGF and integrin family genes examined were expressed more in the C group than in the M group. Conclusions: Type I collagen likely causes an upregulation in a number of angiogenic gene expression patterns as seen in RPE in vitro experiments.

Altered Expression of Genes in Experimentally Induced Myopic Chick Eyes

PURPOSE To identify a casual pathway between the alteration in visual experience, due to form deprivation and hyperopic defocus, and the increase in eye growth, we searched for candidate genes having regulatory effects on eye growth under myopic conditions. METHODS The expression of the brain-derived neurotrophic factor, neurotrophin-3, sonic hedgehog, nerve growth factor, Six-3 and the Lh-2 group of genes in the transcriptional level after experimentally induced myopia (form-deprivation by goggles and by hyperopic defocus using negative spectacle lenses) were evaluated by semiquantitative reverse transcriptional polymerase chain reaction and Northern blot analysis. RESULTS Results showed that only the sonic hedgehog gene was differentially expressed in the experimentally induced myopic retinal samples compared with controls. CONCLUSIONS The sonic hedgehog gene may have regulatory functions in the signaling of the cascade of events that leads to axial elongation and vitreous enlargement of the eye under myopic conditions.

Indocyanine green videoangiography in macular variant of idiopathic polypoidal choroidal vasculopathy

BACKGROUND Fifty patients diagnosed with choroidal neovascularization in age-related macular degeneration were examined by indocyanine green videoangiography. Results were correlated with fundus photographs and fluorescein angiograms. Two patients were diagnosed with the macular variant of idiopathic polypoidal choroidal vasculopathy. CASES Two middle-aged hypertensive women were diagnosed with macular idiopathic polypoidal choroidal vasculopathy. Throughout the follow-up period, both cases showed improved signs and symptoms without worsening of visual acuity, and despite the absence of definitive therapy. OBSERVATIONS Indocyanine green videoangiography demonstrated the characteristic polypoidal lesions in idiopathic polypoidal choroidal vasculopathy better than fluorescein angiography, particularly when blood, exudates, or pigment epithelial detachments blocked visualization of the lesions. CONCLUSIONS Incidence of idiopathic polypoidal choroidal vasculopathy may not be as low as reported, as its presentation mimics choroidal neovascularization in age-related macular degeneration. Differentiation can be made only through indocyanine green videoangiography. Conservative management may be beneficial, as visual prognosis is good.

Enlargement of the Globe With Ocular Malformations in c-Myc Transgenic Mice

PURPOSE To study the ocular development in transgenic mice carrying the mouse c-myc gene under the control of the Mx gene promoter (Mx-c-myc). METHODS Transgenic mice were generated by standard techniques. For histological studies, the tissues were fixed with 10% buffered formalin, embedded in paraffin according to the standard procedure and sliced in 4-microm sections. c-Myc expression was investigated by reverse transcriptase-polymerase chain reaction and Southern blot analysis. RESULTS A line of the Mx-c-myc mice displayed progressive enlargement of the globe with other ocular malformations. Histologically, the enlarged eyes exhibited closed cornea-iris angle, microphakia, corneal epithelial disorders, and attenuation of the inner retinal layers. Developmental analysis of eyes from these Mx-c-myc mice revealed irregular development of the iris and ciliary body at embryonic day 15.5 and the closed angle at 1 week of age. Leaky exogenous c-myc expression was detected in cornea, iris, lens, and retina from the Mx-c-myc mice by reverse transcriptase-polymerase chain reaction and Southern blot analysis. No other developmental abnormalities were observed in the Mx-c-myc mice. The anterior segment of the enlarged eyes showed the closed angle with elongation of the iris and ciliary body. There was no attenuation in the outer retinal layers from the outer plexiform layer to the retinal pigment epithelium. CONCLUSIONS We conclude that the buphthalmos and accompanying changes were not due to expression of the exogenous c-myc in cornea and retina but may be the secondary changes of elevated intraocular pressure. We suggest that Mx-c-myc mice can serve as a useful model for investigating the development of the anterior segment and the genesis of buphthalmos.

Analysis of cytokine mRNAs in murine herpes simplex virus type 1 retinitis

PURPOSE To investigate cytokine mRNA expression during the inflammatory process induced in the contralateral eyes by uniocular inoculation of herpes simplex virus type 1 (HSV-1) via the anterior chamber. METHODS BALB/c mice were inoculated in the anterior chamber with 5 x 10(4) plaque-forming units of HSV-1 (KOS). mRNA was extracted from the inflamed posterior segments of the uninoculated eyes at 0 (control), 9, 11, 14, and 21 days postinoculation (p.i.). Reverse transcription-polymerase chain reaction was performed for semiquantitative analysis of mRNA expression of interleukin (IL)-1beta, IL-2, IL-4, IL-10, IL-12p35, IL-12p40, interferon (IFN)gamma, tumor necrosis factor (TNF)alpha, transforming growth factor (TGF)beta2 and induced nitric oxide synthase (iNOS). RESULTS Peak mRNA expression of iNOS was observed at day 14 p.i. The time profiles of mRNA expression for IL-1beta, IL-2, IL-4, IL-10, IFN-gamma, TNFalpha were similar to that of iNOS, while TGFbeta2, IL-12p35, and IL-12p40 demonstrated a reverse pattern. CONCLUSIONS The kinetics of the analyzed cytokines synchronized with the clinicopathological activity of the experimental murine HSV-1 retinitis. The immunosuppressive cytokines TGFbeta2 and IL-10 demonstrated different peaks of mRNA expressions suggesting that the down-regulation phase of the inflammatory process was controlled by several factors working at different phases.