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Biomedical subjects

T H Pettit

Publications and source records attributed to T H Pettit.

At least 37 records · Page 2Linked to original sources
PubMed1984

Corneal ulcers associated with extended-wear soft contact lenses.

We treated nine myopic and nine aphakic eyes in patients who developed corneal ulcers while wearing extended-wear soft contact lenses. Bacteria were recovered from the corneal ulcers of 13 of 18 patients with Pseudomonas aeruginosa being the pathogen most frequently isolated. Chemical disinfection was used by seven of the nine patients with myopia and eight of the nine with aphakia. Two of nine patients in the myopic group had visual loss to 20/200 and hand movements; five of nine patients in the aphakic group had visual loss to 20/50 or worse. Invasion of the corneal stroma by bacteria may occur after breakdown of the epithelial barrier by contact lens manipulation or after chronic overnight anoxic stress. Thus, the use of soft contact lenses on an extended-wear basis may be complicated by the development of corneal ulcers. Both aphakic and myopic eyes are at risk.

Adult↗
PubMed1984

Corneal endothelial damage with neodymium:YAG laser.

Acute corneal endothelial changes following Nd:YAG laser application were evaluated in two series of rabbits. The first series underwent anterior capsulotomy, while the second series received laser applications at calculated distances ranging from 0.0 mm to 1.8 mm posterior to the endothelium. The rabbits were killed 24 hours after treatment and the endothelium evaluated with scanning electron microscopy. None of the eyes undergoing anterior capsulotomy showed endothelial damage, but the endothelium was focally denuded when laser shots were applied within 1.0 mm of it, and Descemet's membrane was disrupted by laser shots focused within 0.1 mm. Implications for clinical laser surgery are discussed.

Animals↗
PubMed1984

Dematiaceous fungal keratitis following penetrating keratoplasty.

A keratitis with an unusual, sessile, filamentary mass extending into the anterior chamber developed in a patient three weeks after penetrating keratoplasty. The causative organism was identified as Exophilia (Wangiella) dermatitidis, a dematiaceous fungus. The infection was cured with a combination of medical and surgical therapy. Inoculation of the isolate into rabbit corneas produced a similar keratitis from which the same organism was cultured. Miconazole levels measured in corneal tissue removed at surgery were approximately 25 times greater than the minimum inhibitory concentration for the fungal isolate.

Adult↗
PubMed1983

2.5% v 10% phenylephrine in maintaining mydriasis during cataract surgery.

A 10% viscous solution of phenylephrine hydrochloride was more effective than a 2.5% aqueous solution of phenylephrine hydrochloride in maintaining mydriasis during extracapsular cataract surgery. The pupil area after nucleus expression was 57% larger with the stronger phenylephrine concentration. The difference in pupil area was greater in darkly pigmented irides (114%) than in moderately pigmented (70%) or lightly pigmented irides (12%). Mean BP elevations following phenylephrine administration were not higher in the group receiving the 10% solution than in the group receiving the 2.5% solution. In darkly pigmented irides, a 10% viscous solution of phenylephrine hydrochloride is more effective than a 2.5% concentration in maintaining mydriasis during cataract surgery.

Adult↗
PubMed1983

Diabetes mellitus and intraocular lens implantation.

Prospective evaluation of extracapsular cataract extraction with posterior chamber intraocular lens (ECCE-posterior chamber IOL) in 234 eyes of 20 diabetics, with and without nonproliferative retinopathy, and 209 nondiabetics demonstrated no statistically significant difference in operative or postoperative complications. A postoperative final visual acuity of 20/40 or better was achieved in 65% of diabetic surgical eyes and in 90% of nondiabetic surgical eyes, a difference that was statistically significant (P = 0.0049). When eyes with diabetic retinopathy or other pre-existing ophthalmic disease responsible for decreased vision were excluded, postoperative visual acuity of 20/40 or better was obtained in 93% of diabetic eyes and 96% of nondiabetic eyes, a difference that was not statistically significant (P = 0.5045). Therefore, the relatively less favorable outcome of ECCE-posterior chamber IOL surgery in diabetics, with or without nonproliferative retinopathy, is due to greater frequency of retinopathy or other ophthalmic disease responsible for decreased vision. Based on this study and all available information, guidelines regarding diabetes mellitus and intraocular lens implantation are presented.

Aged↗
PubMed1983

Acquired immune deficiency syndrome. Ocular manifestations.

The acquired immune deficiency syndrome (AIDS) is a recently described disorder of cellular immunity in homosexuals, intravenous drug abusers, and Haitians. Manifestations include Kaposi's sarcoma, Pneumocystis carinii pneumonia, and other opportunistic infections. Ophthalmic and autopsy examinations of 30 patients at UCLA revealed frequent ocular abnormalities. Findings included cotton-wool spots (16 patients), cytomegalovirus retinitis (eight patients), conjunctivitis and keratitis (four patients), conjunctival Kaposi's sarcoma (three patients), Mycobacterium avium intracellulare choroidal granulomas (one patient), and retinal periphlebitis (one patient). We feel that the presence of cotton-wool spots in patients with this syndrome indicates a poor prognosis. Immunologic and electronmicroscopic studies of cotton-wool spots revealed no infectious agents or immunoglobulin deposition. Cytomegalovirus retinitis always was associated with a fatal outcome. The retinitis was characterized by an acute inflammatory reaction in 50% of patients. Ophthalmologists should be aware of the syndrome and its ocular manifestations.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Maintenance of mydriasis with epinephrine during cataract surgery.

The pupillary response to various doses of intraocular epinephrine (0.1 ml of 1:16,000, 1:32,000, 1:64,000, 1:80,000, or 1:96,000) was studied in 55 consecutive patients during extracapsular cataract surgery. The 1:16,000 epinephrine concentration provided a mean 0.74 mm increase in pupil diameter (range 0.0 to 1.7 mm) when administered to re-dilate the pupil after nucleus expression. The mean increase in pupil area with 1:16,000 epinephrine was 27% which greatly facilitated removal of lens cortex in most cases. However, 25% of all pupils failed to dilate with epinephrine 1:16,000. The other concentrations provided essentially the same mydriasis as the 1:16,000 concentration. Pupils smaller than 6 mm dilated more easily than pupils larger than 6 mm. Iris color, age, or sex had no significant effect on the mydriatic response. It is concluded that an extremely dilute concentration of epinephrine (i.e., 1:96,000 or less) may be effective in maintaining mydriasis during cataract surgery.

Aged↗
PubMed1983

Oxygen permeability of rabbit and human corneal stroma.

Oxygen permeability (Dk) of 15 rabbit and 19 human cornea stromal samples was measured by conventional polarographic means at 36 C. Hydration and thickness were also measured. Rabbit stromal permeability was found to be about 26 X 10(-11) ml O2 cm2/sec ml mmHg at normal in vivo hydration; in vivo human cornea stromal permeability is probably less than 29 X 10(-11) ml O2 cm2/sec ml mmHg.

Adolescent↗
PubMed1982

Ocular disorders associated with a new severe acquired cellular immunodeficiency syndrome.

Among the prominent features of a newly described acquired cellular immunodeficiency syndrome that affects previously healthy male homosexuals are multiple opportunistic infections and Kaposi's sarcoma. Immunosuppression induced by cytomegalovirus infection may play a major role in the pathogenesis of this disorder. We have performed ophthalmic examinations on seven such patients and found ocular abnormalities in all cases. Six patients were examined during the course of their illness and one patient at autopsy only. Each patient had several cotton-wool spots in the affected eye. Other ocular findings included cytomegalovirus retinitis, severe retinal periphlebitis, and conjunctival Kaposi's sarcoma (one case each).

Candidiasis, Chronic Mucocutaneous↗
PubMed1982

Complications of contact lens wear after radial keratotomy in an animal model.

In 12 rabbits radial keratotomy was performed on one eye with no treatment to the contralateral eye. Cellulose acetate butyrate contact lenses were fitted bilaterally for extended wear. The eyes were monitored weakly for three weeks with a standardized slit-lamp grading method. Corneal neovascularization occurred earlier and progressed further in eyes that had radial keratotomy than in the control eyes (P less than .0025). These results suggested that patients who require contact lenses after radial keratotomy may be at higher risk for complications such as corneal neovascularization.

Animals↗
PubMed1982

Flurbiprofen in the treatment of corneal neovascularization induced by contact lenses.

Cellulose acetate butyrate extended-wear contact lenses were fitted bilaterally on ten New Zealand albino rabbits. We administered flurbiprofen 0.03% solution topically to the experimental eyes and vehicle solution to the contralateral control eyes four times a day in a random, masked fashion beginning 24 hours before the contact lens was fitted. Corneal neovascularization, which developed in all eyes by the 25th day of contact lens wear, was significantly suppressed by flurbiprofen treatment (mean vessel length was 1.5 +/- 0.4 mm for the treated eyes and 3.0 +/- 0.3 mm for the control eyes; P less than .005). Topical administration of a noncorticosteroidal anti-inflammatory agent may be an effective treatment for corneal neovascularization induced by contact lenses.

Administration, Topical↗
PubMed1982

Inhibitors of surgically induced miosis.

Miosis induced by surgical trauma is a frequent problem during extracapsular cataract surgery. In experimental surgery on rabbits, the inhibitory effect on pupillary constriction of cyclo-oxygenase inhibitors, local anesthetics, capsaicin (presumed substance P depletor), sympathomimetic agents, and anticholinergic agents were studied. In eyes predilated with tropicamide, iris massage caused marked pupillary constriction. Randomized pretreatment with the following agents significantly inhibited miosis: flurbiprofen, P less than 0.005; topical anesthetics (benoxinate, P less than 0.001, cocaine, P less than 0.05, proparacaine, P less than 0.005); and retrobulbar capsaicin, P less than 0.005. No significant inhibition was shown with topical indomethacin aqueous solution (P less than 0.15), topical tetracaine (P less than 0.15), or retrobulbar lidocaine (P less than 0.15). No single agent or combination of agents blocked the total miotic response; however, a combination of flurbiprofen, benoxinate, and capsaicin blocked more than two third of the miosis. Phenylephrine, a sympathomimetic (active) mydriatic agent, was more effective than anticholinergic (passive) mydriatic agents in obtaining maximal pupillary size after surgical iris massage.

Anesthetics, Local↗
PubMed1981

UCLA clinical trial of radial keratotomy. Preliminary report.

A clinical trail of radial keratotomy ws begun under a strict research protocol at the Jules Stein Eye Institute in November 1979. The results for the first 52 eyes undergoing radial keratotomy are reported three months after surgery. Preoperatively uncorrected visual acuity was less than 20/200 in all 52 eyes. and postoperative visual acuity was less than 20/200 in 11 eyes (21%). Three months postoperatively, uncorrected visual acuity was 20/40 or better in 27 eyes (52%) and 20/20 or better in 13 eyes (25%). Postoperatively the best-corrected visual acuity decreased in 10 eyes (20%), but maximum decrease in any eye was one line of snellen letters. Preoperatively mean refractive error was -4.9 (/+-2.2) diopters, and postoperatively the mean decrease in myopia was 3.4 (/+-2.2) diopters. Postoperatively 13 eyes (25%) had a hyperopic refractive error of +0.25 to +3.25 diopters, but all of these eyes were able to accommodate and obtain 20/20 visual acuity without glasses. Postoperatively there was no statistically significant change in axial length, anterior chamber depth, or scleral rigidity, but there was a mean corneal endothelial cell loss of 10% (P = 0.0002). Decrease in myopia achieved by radial keratotomy did not correlate with the steepness of corneal curvature, corneal diameter, or scleral rigidity. Three months after surgery, significant symptoms of glare were present in 10 eyes (20%0, and annoying variable visual acuity was noted in five eyes (10%).

Adult↗
PubMed1981

Familial Nevus of Ota.

A white family with three generations (one by history) showing the clinical picture of nevus of Ota is presented. In the two generations examined, no evidence of uveal malignant melanoma was found. This is the first such family reported in the English literature and the fifth family in the world literature. It shows the importance of a good family history in dealing with a patient with a nevus of Ota. Affected family members should be examined carefully to rule out uveal malignant melanoma until the questions surrounding its reported association with nevus of Ota can be resolved.

Aged↗
PubMed1980

Viral antigens in the immune ring of Herpes simplex stromal keratitis.

Corneal tissue obtained during superficial keratectomy from a patient with herpesvirus disciform keratitis was studied by immunoelectron microscopy. Clinically, this cornea had a dense central infiltrate with a circumferential opaque ring histologically resembling the immune ring described by Wessely. Histologically, along the line of altered keratocytes and ground substance, an infiltration of inflammatory cells was found. Herpesvirus particles were seen by electron microscopy in the corneal stroma, but these virus particles had abnormal, noninfective forms such as empty capsids and incomplete virions. By immunoelectron microscopy with a peroxidase-labeled antiherpesvirus antibody reagent, herpes-virus antigens were localized inthe corneal keratocytes and in the corneal stroma. The major localization of the virus antigens was in association with the herpes virions and surrounding vacuoles in the keratocyte nucleus and in the corneal stroma in the area of degenerating keratocytes. These findings support the view of a hypersensitivity mechanism in the pathogenesis of herpes simplex virus disciform keratitis.

Antigens, Viral↗