Biomedical subjects

J B Harlan

Publications and source records attributed to J B Harlan.

7 recordsLinked to original sources

PubMed2004

Vitreous levels of pigment epithelium-derived factor and vascular endothelial growth factor: implications for ocular angiogenesis.

PURPOSE: Pigment epithelium-derived factor (PEDF) has been demonstrated to suppress ocular angiogenesis in several animal models. In this study, we sought to measure the levels of PEDF and vascular endothelial growth factor (VEGF) in the vitreous of patients with and without ocular neovascular disorders. DESIGN: Case-control study of patients undergoing intraocular surgery for a variety of neovascular and nonneovascular conditions. METHODS: Vitreous samples were collected from 65 eyes of 65 patients with no neovascular disorder (n = 24), choroidal neovascularization (n = 9), active proliferative diabetic retinopathy (n = 16), and inactive proliferative diabetic retinopathy (n = 16). The levels of VEGF and PEDF in these vitreous samples were determined by enzyme-linked immunosorbent assay. RESULTS: The VEGF levels were at or below the level of detectability in the reference and choroidal neovascularization groups. The VEGF levels were significantly elevated in both the active and inactive PDR groups, and significantly higher in the active PDR group as compared with the inactive PDR group. The PEDF levels, which were present at relatively high concentrations in all groups, were higher in patients with active PDR compared with the control and choroidal neovascularization groups. CONCLUSIONS: High levels of immunoreactive PEDF are present in the vitreous of individuals with or without ocular neovascularization, but PEDF levels are significantly higher in patients with active PDR compared with patients with choroidal neovascularization or nonneovascular retinal diseases. Although these results do not preclude the possibility that endogenous PEDF helps to modulate ocular neovascularization, they do not support ischemia-induced downregulation of PEDF as a mechanism for such modulation.

Adult↗

PubMed2002

Evaluation of patients with ocular trauma.

When confronted with the ocular trauma patient, the initial evaluation always begins with the assessment of the patient. Once it has been determined that the patient is stable, and other serious nonocular injuries have been addressed, a thorough medical/surgical history is taken followed by a more focused ocular history. Key elements include prior surgery, trauma, and any previously existing eye disease. A full examination is carried out in a methodical and rational fashion, beginning with gross external inspection. Visual acuity is measured in each eye independently. Optic nerve function is assessed by testing for a relative afferent pupillary defect, performing gross confrontational visual field testing, identifying any relative difference in subjective brightness perception, and checking color vision. If appropriate, the IOP is measured and a careful slit lamp examination is performed, combined with dilated indirect ophthalmoscopy. Obvious open globe injury can often be appreciated with a simple penlight examination. Uncooperative patients should be examined under anesthesia in a controlled, monitored setting involving experienced critical care personnel. Additional information may be obtained utilizing ancillary testing (primarily CT and ultrasonography). If the combination of clinical findings and ancillary testing is still not definitive, then formal exploration under anesthesia in the operating room in recommended. Photodocumentation is recommended whenever feasible. Figs. 1-14 provide an overview of many of the points stressed above.

Diagnostic Techniques, Ophthalmological↗

PubMed2001

Macular translocation: unifying concepts, terminology, and classification.

PURPOSE: To describe some unifying concepts, terminology, and classification of macular translocation so as to facilitate communication within the scientific community. METHODS: A panel of ophthalmologists with expertise in macular translocation reviewed available data and developed some unifying concepts, terminology, and classification of macular translocation. RESULTS: Macular translocation may be defined as any surgery that has a primary goal of relocating the central neurosensory retina or fovea intraoperatively or postoperatively specifically for the management of macular disease. It may be classified according to the size of the retinotomy and, where applicable, the technique of chorioscleral shortening used. The direction of macular translocation is denoted by the movement of the neurosensory macula relative to the underlying tissues. Effective macular translocation may be defined as successful intraoperative or postoperative relocation of the fovea overlying a subfoveal lesion to an area outside the border of the lesion. The concepts of minimum desired translocation and median postoperative foveal displacement can give some useful idea of the likelihood of effective macular translocation before surgery. CONCLUSIONS: Use of a common standardized terminology for macular translocation will facilitate communication within the scientific community and enhance further research in this area. However, the definitions, terms, classification, and concepts concerning macular translocation are likely to continue to evolve as macular translocation undergoes further modifications and refinements.

Humans↗

PubMed2001

Effective nasal limited macular translocation.

PURPOSE: To describe a case of effective foveal displacement toward the optic disk (nasal limited macular translocation) in a patient with a large subfoveal choroidal neovascularization secondary to age-related macular degeneration. METHODS: Case report. RESULTS: A 77-year-old white man presented with decreased vision of 20/400 due to subfoveal predominantly occult CNV secondary to age-related macular degeneration in the left eye. The CNV, measuring 9 Macular Photocoagulation Study disk areas in size, was centered temporally relative to the fovea with a minimum desired translocation of 650 microm for nasal macular translocation. The patient underwent nasal LMT with punctate retinotomy and temporal chorioscleral infolding, followed by postoperative head-positioning on his right side. Effective LMT was achieved with a postoperative nasal foveal displacement of 1400 microm. The entire CNV was ablated with laser photocoagulation postoperatively. His vision improved to 20/40 6 months postoperatively. CONCLUSION: Nasal LMT is feasible and may be considered in patients with subfoveal CNV centered temporally relative to the fovea.

Aged↗

PubMed1999

Effect of humidity on posterior lens opacification during fluid-air exchange.

OBJECTIVE: To study the relationship of humidity and the rate of lens opacity formation during fluid-air exchange using an animal model. METHODS: Vitrectomy and fluid-air exchange was carried out using 16 eyes of 8 pigmented rabbits. One eye of each rabbit was exposed to dry air and the fellow eye received humidified air using an intraocular air humidifier. In each case, the percent humidity of the intraocular air was measured using an in-line hygrometer. Elapsed time from initial air entry to lens feathering was recorded for each eye, with the surgeon-observer unaware of the percent humidity of the air infusion. RESULTS: In each rabbit, use of humidified air resulted in a delay in lens feathering (P<.02), with an overall increase in time to feathering of 80% for humidified air vs room air. CONCLUSIONS: Use of a humidifier during fluid-air exchange prolongs intraoperative lens clarity in the rabbit model, suggesting that humidified air should prolong lens clarity during phakic fluid-air exchange in patients. CLINICAL RELEVANCE: Use of humidified air during vitrectomy and fluid-air exchange may retard the intraoperative loss of lens clarity, promoting better visualization of the posterior segment and enhancing surgical performance.

Air↗

PubMed1997

Histologic study of a shielded macula.

PURPOSE: To illustrate the histologic changes at the macula of an eye shielded from focused light for 76 years. Age-related macular degeneration with a central, subretinal, fibrous scar was present in the fellow eye. METHODS: Autopsy examination of both eyes of a 91-year-old man was performed. The superior half of the macular area of the shielded eye was studied by light microscopy, and the inferior half was studied by electron microscopy. Serial sections through the macular area of the fellow eye were prepared and studied. RESULTS: The shielded eye contained basal laminar deposits up to 6.0 microns in thickness and basal linear deposits up to 1.0 micron in thickness in the macular area. The photoreceptor outer and inner segments of the outer nuclear layer were intact. The macular area of the fellow eye contained a two-component, vascularized, disciform scar that measured up to 250 microns in one area, with retinal pigment epithelial tears at the nasal and temporal margins. Extensive photoreceptor layer atrophy was present. CONCLUSIONS: Such marked asymmetry of macular degeneration in this case may be further evidence of the role of light exposure in the development of age related macular degeneration.

Aged↗

PubMed1993

Light-induced deposits in Bruch's membrane of protoporphyric mice.

Photosensitization of choriocapillary endothelium with blood-borne photosensitizers, such as protoporphyrin IX, has been proposed as a mechanism for the choriocapillary sclerosis and Bruch's membrane deposits seen in age-related macular degeneration. Utilizing a mouse model of protoporphyria with approximately a 10-fold increase in protoporphyrin IX level and exposure to blue light (14 microW/cm2; bandwidth, 390 to 430 nm), a time- and light-dependent increase in choriocapillary and sub-retinal pigment epithelium basal laminar-like deposits could be demonstrated at 7 months by transmission electron microscopy. Thickening of the choriocapillary endothelial basement membrane with a homogeneous electron-dense material was first noted in protoporphyric mice exposed to blue light for 13 weeks. At 28 weeks the experimental animals exhibited a thick band of homogeneous deposits at the level of the choriocapillary basement membrane and electron-dense fibrillogranular deposits of varying sizes along the inner aspect of Bruch's membrane, with fibrils measuring up to 16 nm, with a periodicity of 13 nm. These deposits contributed to an overall thickening of Bruch's membrane with narrowing of the choriocapillaris. The morphologic appearance and localization of these deposits within Bruch's membrane of this animal model are similar to previously described deposits noted in the aging Bruch's membrane prior to the development of age-related macular degeneration.

Animals↗