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Biomedical subjects

M F Refojo

Publications and source records attributed to M F Refojo.

123 records · Page 7Linked to original sources
PubMedDate not supplied

Effect of silicone oil on the cornea.

Silicone oil can dissolve about seven times more oxygen that can water. Placed in a depot between a rigid scleral lens and the corneal surface, silicone oil might thus be useful for treating severe dry-eye patients and for preventing exposure keratitis. To explore this possibility, generic (300, 500, 1000, and 12,500 cs) and medical-grade (1000 cs) silicone oils were tested on rabbit eyes. When oxygenated silicone oil was placed in a cup formed by the lids and hanging sutures and allowed to remain for 3 h on the eyes of anesthetized rabbits, the immediate reaction was mild epithelial edema. By 3 to 6 days later, the thickness of the epithelium and of the entire cornea had increased irregularly. The most common histologic finding was intracellular epithelial edema, particularly in the basal cell layer. The reaction was most intense for the generic oils of the lowest viscosities. The medical-grade oil was the best tolerated, but it too affected epithelial and corneal thickness. Ultrastructural studies of treated eyes showed abnormal epithelial surfaces but no major changes within the epithelial cells. Biochemical analysis showed some decrease of glycogen in the corneal epithelium of eyes kept under oxygenated medical-grade silicone oil. A smaller decrease of glycogen level persisted after 2 days exposure of the treated eye to air, suggesting that the corneal epithelium was injured by a mechanism other than hypoxia.

Animals↗
PubMedDate not supplied

Current status of biomaterials in ophthalmology.

The artificial materials currently used in ophthalmology are reviewed. Those include poly(methyl methacrylate) in contact lenses, keratoprostheses, and intraocular lenses; cellulose acetate butyrate and the siloxane-containing polymethacrylates in contact lenses; the silicones in contact lenses, scleral buckling materials, and drainage implants in glaucoma; the hydrogels for contact lenses and retinal surgery implants; and the cyanoacrylate adhesives for corneal perforations and ulcers. The properties of the materials and their relationship to ocular tissues, as well as the advantages and disadvantages of their use in the eye are discussed. Probable future advances of biomaterials in ophthalmology are also discussed.

Biocompatible Materials↗
PubMedDate not supplied

Perfluoroether liquid as a long-term vitreous substitute. An experimental study.

A commercial perfluoroether liquid, Fomblin-H Fluorinated Fluid, which is transparent and viscous, was investigated as a possible long-term vitreous substitute. The material belongs to a family of perfluorocarbon derivatives that are generally inert and nontoxic. A space for the vitreous substitute was created in rabbit eyes by a vitreous compression technique using perfluoropropane gas. Fomblin caused gliosis of the retina at 1 month after intravitreous injection. Preretinal membrane formation and retinal disorganization and detachment occurred in two of four eyes enucleated at 3 months, and in all five eyes enucleated at 4 or 6 months. Vacuoles presumably filled with Fomblin were localized histopathologically within the retina. In control eyes injected with medical-grade silicone oil, abnormalities were limited to moderate edema of the nerve fiber and ganglion cell layer. Fomblin was not as well-tolerated by the rabbit retina as was medical-grade silicone oil. Fomblin is not a suitable vitreous substitute.

Animals↗
PubMedDate not supplied

Hydrogel implant for scleral buckling. Long-term observations.

The authors report long-term follow-up clinical observations of 82 eyes in which episcleral or intrascleral hydrogel implants were used as buckles in the repair of rhegmatogenous retinal detachment. Three fourths of the eyes were observed for 24 months or more. The implant material provided a durable and effective scleral buckle, did not produce erosion or infection, and was tolerated well by all patients.

Adolescent↗
PubMedDate not supplied

Vitreous substitute. Experimental studies and review.

We studied a synthetic hydrogel, PHEA [poly(2-hydroxyethyl acrylate)], experimentally. The material is transparent, autoclavable , highly viscous, nonabsorbable, easily injectable, cohesive, and does not fragment on passage through small-gauge needles. Results in animal studies revealed that injection of PHEA into the vitreous cavity promoted inflammatory changes such as vitreous haziness , membrane formation, and chorioretinal atrophy. Histopathologic studies showed extensive retinal disorganization, chorioretinal scarring, and vitritis . We reviewed the literature and concluded that an ideal vitreous substitute for long-term use in complex cases of retinal detachment is not available at this time.

Animals↗