Search PubMed⌕ Search

Biomedical subjects

H Lewis

Publications and source records attributed to H Lewis.

At least 19 recordsLinked to original sources
PubMed1992

Macular phototoxicity caused by fiberoptic endoillumination during pars plana vitrectomy.

Three cases of retinal phototoxicity were caused by light from the endoilluminator used in vitrectomy. Preoperative clinical examination, color photography, and fluorescein angiography in all three cases failed to disclose retinal pigment epithelial changes. Postoperative clinical findings, photographs, and fluorescein angiograms are highly suggestive of the presence of retinal phototoxicity. The characteristics of these lesions and surgical conditions implicate the endoilluminator as the source of photic injury. The macular lesions were noted within one week of the surgical procedure, measured between 2 and 5 disk diameters in size, involved the fovea in two eyes, and resulted in marked decrease in visual acuity in two of three eyes, with persistence in one eye. Initially, whitening of the outer retina was present, but was replaced by pigmentary mottling at the level of the retinal pigment epithelium within a few weeks. Preventive measures to avoid macular phototoxicity associated with vitrectomy are discussed.

Adult↗
PubMed1992

Noncontact transscleral neodymium-YAG laser photocoagulation of the pigmented rabbit retina.

We studied the applicability of transscleral delivery of noncontact neodymium-YAG laser in its free-running mode (10 milliseconds) in creating chorioretinal lesions in 16 rabbits. After the laser was applied, the eyes were studied by indirect ophthalmoscopy, light microscopy, and electron microscopy. Lesions generated with low-energy and defocus settings were characterized by intact sclera, variable clumping of the pigmented choroidal lamellae, destruction of choriocapillaris, and loss of the retinal pigment epithelium. In the central region of laser exposure, vacuolization of the retinal pigment epithelium and outer retina were observed. No scleral changes were noted. In contrast with lesions produced with high-energy and/or high-defocus settings, these lesions were produced without hemorrhagic phenomena or breaks in the neurosensory retina. These data demonstrate that noncontact transscleral neodymium-YAG photocoagulation is capable of very localized, selective destruction of the retina and choroid and deserves further study.

Animals↗
PubMed1992

Vitrectomy for diabetic macular traction and edema associated with posterior hyaloidal traction.

Pars plana vitrectomy with separation of the posterior hyaloid was performed in 10 eyes with diabetic macular edema and traction associated with a thickened and taut premacular posterior hyaloid. Nine of the 10 eyes had previous macular photocoagulation. Preoperative fluorescein angiography showed a deep and diffuse pattern of leakage in the macula. Intraoperatively, the attached and thickened posterior hyaloid was lifted and separated from the retina. Postoperatively, vision improved in nine eyes. The macular traction and edema resolved in eight eyes and decreased in two. Complications included a vitreous hemorrhage, a rhegmatogenous retinal detachment, cataract formation, and a mild epimacular membrane, each occurring in one eye. Vitreous surgery can improve the visual prognosis of some eyes with diabetic macular traction and edema associated with a thickened and taut posterior hyaloid.

Adult↗
PubMed1992

Management of giant retinal tears without scleral buckling. Use of radical dissection of the vitreous base and perfluoro-octane and intraocular tamponade.

The introduction of intraoperative perfluorocarbon liquids in the management of giant retinal tears has allowed exact anatomic reapposition of the retina and the giant retinal tear. Therefore, the authors managed 11 eyes with giant retinal tears and no proliferative vitreoretinopathy without scleral buckling. Maximum removal of the basal vitreous gel was performed in all cases, and perfluoro-octane was used intraoperatively to unfold the inverted posterior flap and reattach the retina completely. Endophotocoagulation was applied to the edges of the tear and perfluoropropane or silicone oil was used as an intraocular tamponade. Although 1 eye required reoperation for a redetachment from posterior proliferative vitreoretinopathy, all retinas were reattached with final visual acuity of 5/200 or better in 9 eyes. Eight additional major procedures were necessary in seven eyes: removal of silicone oil in four (with removal of perisilicone proliferation in three), repeat vitrectomy and membrane removal with photocoagulation twice in one eye, cataract extraction in one eye, and removal of a macular pucker in one eye. Four eyes required postoperative fluid-gas exchange and three eyes had tissue plasminogen activator injections into the anterior chamber for postoperative fibrin reactions.

Adolescent↗
PubMed1992

Treatment of dislocated crystalline lens and retinal detachment with perfluorocarbon liquids.

Removal of a crystalline lens dislocated into the vitreous cavity can be hazardous, particularly in the presence of a retinal detachment. Hard pieces of nuclear material may be difficult to extract and may repeatedly fall onto the retina when emulsification is attempted in the vitreous cavity. Cases involving four eyes with dislocated crystalline lens and rhegmatogenous retinal detachment, into which liquid perfluorocarbon was injected after vitrectomy to float the dislocated lens material off the retina and reattach the retina, are reported. The dislocated lens was removed while floating on the perfluorocarbon liquid, which also provided a cushion that prevented dropped fragments of lens from traumatizing the retina. In all four cases, surgery was not associated with complications and resulted in improvement in visual acuity and retinal reattachment.

Adult↗
PubMed1991

Decrease in the risk of bilateral acute retinal necrosis by acyclovir therapy.

We reviewed the course of 54 patients who had unilateral acute retinal necrosis at initial examination. Thirty-one patients were treated with acyclovir, whereas 23 were not. Of the 31 patients treated with acyclovir, 27 (87.1%) had fellow eyes that remained disease-free throughout a median follow-up of 12 months. Of the 23 patients not treated with acyclovir, seven (30.4%) had fellow eyes that remained disease-free throughout a median follow-up of 11 months. Survival analysis indicated that the fellow eyes of the group of patients treated with acyclovir were more likely to remain disease-free than the fellow eyes of the group not treated with acyclovir (P = .0013). Two years after initial onset, the proportion of fellow eyes that remained disease-free was 75.3% for the group treated with acyclovir and 35.1% for the group not treated with acyclovir. These results suggest that acyclovir treatment reduces the risk of involvement of the fellow eye in patients with acute retinal necrosis.

Acyclovir↗
PubMed1991

Scleral buckling for rhegmatogenous retinal detachment associated with severe myopia.

From Jan. 1, 1980, to Dec. 31, 1989, we performed scleral buckling surgery on 48 eyes of 46 patients for rhegmatogenous retinal detachments associated with severe myopia (greater than 5.00 diopters). Forty eyes of 38 patients were observed for at least six months, and the mean follow-up period was 46 months. Intraoperative complications occurred in four of 48 eyes (8%) and included retinal incarceration (two eyes), choroidal hemorrhage (one eye), and choroidal detachment (one eye). Three of the 40 eyes (7.5%) followed up for more than six months developed a recurrent retinal detachment and underwent a revision of the scleral buckle. At the last follow-up examination, the retinas of all 40 eyes were totally reattached. Final visual acuity of 20/40 or better was attained in 26 of 40 eyes (65%). Because of the low rate of intraoperative complications and the high rate of success, scleral buckling is recommended for most patients with rhegmatogenous retinal detachments associated with severe myopia.

Adolescent↗
PubMed1991

Tissue plasminogen activator treatment of experimental subretinal hemorrhage.

To determine if tissue plasminogen activator, a clot-specific fibrinolytic agent, could eventually be used to assist in the clearance or removal of subretinal hemorrhage, we studied the effect of subretinal injections of tissue plasminogen activator, autologous blood, balanced salt solution, and the combination of either tissue plasminogen activator or balanced salt solution after subretinal injection of autologous blood on retinal morphologic characteristics and clearance of subretinal hemorrhage in the albino rabbit. No morphologic evidence of tissue plasminogen activator toxicity was found in the rabbit retina at a dose of 25 to 50 micrograms/0.1 ml. Subretinal hemorrhage cleared faster after subretinal injection of tissue plasminogen activator when compared to balanced salt solution (P = .0005) but did not completely prevent overlying retinal degeneration. Both tissue plasminogen activator and balanced salt solution were found to decrease the toxic effects of subretinal blood on the morphologic characteristics of the rabbit retina, and this effect can be explained at least partly by dilution of the subretinal blood.

Animals↗
PubMed1991

Causes of failure after initial vitreoretinal surgery for severe proliferative vitreoretinopathy.

We performed initial vitreoretinal surgery on 81 eyes with rhegmatogenous retinal detachments complicated by severe proliferative vitreoretinopathy. Of 81 eyes, 68 (84%) had undergone previous scleral buckling. We performed vitreous base dissection on all 18 eyes (22%) that had anterior proliferative vitreoretinopathy. With one vitreoretinal operation, 66 of 81 eyes (81%) remained totally reattached. The main cause of initial anatomic failure and reoperation was either new or recurrent proliferation at the vitreous base. With additional vitreoretinal surgery and after a mean follow-up period of 19 months, 73 of 81 retinas (90%) were totally reattached. The final causes of anatomic failure were anterior proliferative vitreoretinopathy and proliferation from relaxing retinotomies. Of the 73 successfully reattached eyes, 62 (85%) had postoperative visual acuity of 5/200 or better.

Female↗
PubMed1991

Causes of failure after repeat vitreoretinal surgery for recurrent proliferative vitreoretinopathy.

During the last two years, we performed vitreoretinal surgery on 37 eyes with retinal detachments and recurrent severe proliferative vitreoretinopathy in 37 patients who had had previous failed scleral buckling and vitreous surgery for proliferative vitreoretinopathy. Anterior proliferative vitreoretinopathy was present in 32 of 37 eyes (86%); posterior proliferative vitreoretinopathy of fixed retinal folds in four quadrants of narrow or closed funnel shape occurred in 23 of 37 eyes (62%); and subretinal proliferation was noted in 16 of 37 eyes (43%). The retinas in 12 eyes (32%) redetached from new or recurrent anterior proliferative vitreoretinopathy in nine eyes, reopening of pre-existing retinal breaks in two eyes, or recurrent posterior periretinal proliferation in one eye. With additional vitreoretinal procedures in six eyes and after a mean follow-up period of 11 months, 27 of 37 retinas (73%) were totally reattached, and an additional five eyes (13%) had retinal reattachment posterior to the scleral buckle. Of the 32 patients with posterior retinal reattachment, final visual acuity of 5/200 or better was attained in 19 eyes (59%).

Adolescent↗
PubMed1991

Vitreous surgery for retinal detachment associated with choroidal coloboma.

We report the results of vitreous surgery in seven eyes with retinal detachments caused by retinal breaks at the margin of, or within, a choroidal coloboma. All seven eyes (100%) were reattached; visual acuities in five (71%) of the seven eyes improved from preoperative levels. Vitrectomy was combined with air-fluid exchange and endodrainage through preexisting retinal breaks or planned retinotomies in all but one of the cases. Part or all of the rim of the choroidal coloboma in six eyes underwent endophotocoagulation. The two eyes that did not experience postoperative visual improvement underwent intraoperative endolaser treatment 360 degrees around the optic nerve. If peripapillary endophotocoagulation is performed, especially through the papillomacular bundle, nerve fiber damage may occur and prevent visual recovery, despite retinal reattachment. For eyes with retinal detachment associated with choroidal colobomas involving the optic nerve, postoperative laser treatment through the papillomacular bundle may be preferable.

Adolescent↗
PubMed1991

A technique for facilitated visualization and dissection of the vitreous base, pars plana, and pars plicata.

We describe a technique to facilitate visualization of the vitreous base, pars plana, and pars plicata during vitreous surgery. This technique takes advantage of an externally applied fiberoptic light source coupled with scleral depression to enable direct viewing of the ciliary processes and anterior vitreous base. No special instrumentation or alteration in pars plana vitrectomy techniques is required. We have used this technique to enhance anterior dissection during vitrectomy surgery in the aphakic and pseudophakic eye associated with proliferative vitreoretinopathy, diabetic retinopathy, epithelial down-growth syndromes, and postvitrectomy fibrin formation.

Eye Diseases↗
PubMed1991

Otogenic Fusobacterium necrophorum meningitis.

A case of meningitis secondary to acute suppurative otitis media in a previously healthy child is reported. The only organism isolated from blood after aerobic and prolonged anaerobic culture was identified as Fusobacterium necrophorum. Complete recovery followed treatment with surgery and prolonged antibiotic therapy. The role of anaerobes in the development of meningitis, the isolation and identification of Fusobacterium necrophorum, the clinical presentations of F. necrophorum infection and the choice of antibiotics in the treatment of these infections are discussed.

Acute Disease↗
PubMed1991

Altered cell-mediated immunity to group A haemolytic streptococcal antigens in chronic plaque psoriasis.

The proliferative lymphocyte response to sonicated group A, beta-haemolytic streptococci (Strep-A) was measured by thymidine incorporation in 78 patients with psoriasis (guttate, chronic plaque or both). Lymphocytes from 72 of these patients were also cultured with streptokinase/streptodornase (SK/SD), and 20 of the patients with chronic plaque psoriasis were further tested with PPD, Candida albicans and sonicated Streptococcus mutans, a bacterial type not associated clinically with psoriasis. The median stimulation index (SI) of the psoriasis group to the Strep-A preparation was significantly higher than that of a group of 27 non-psoriatic individuals (P less than 0.05). Within this group, only the patients with chronic plaque psoriasis (n = 42) showed a significantly increased proliferative response compared to the non-psoriatic controls (median SI = 123.8 and 31.9, respectively, P less than 0.01). Although the lymphocyte response of the chronic plaque group to SK/SD was also markedly higher than that of the control group, this difference did not reach statistical significance. In addition, these patients did not show significantly increased responses to any of the other antigens tested, including S. mutans. No correlation was observed between the degree of proliferation to Strep-A and disease extent or activity. Similarly, ASO titres, which were raised in 11 out of 23 guttate and three out of nine chronic plaque psoriasis patients tested, did not correlate with the proliferative responses observed.

Adolescent↗
PubMed1991

Surgical management of retinal detachment associated with the acute retinal necrosis syndrome.

We operated on nine eyes in eight patients with retinal detachment associated with acute retinal necrosis (ARN) syndrome. The patients were treated with scleral buckling, vitreoretinal surgery, or a combination of these treatments. Vitrectomised eyes underwent combinations of lensectomy, membrane dissection, scleral buckling, air-fluid exchange, endolaser photocoagulation, cryotherapy, and retinal tamponade with C3F8 gas or SF6 gas. Macular attachment was achieved in eight (89%) eyes. Vision improved in seven (78%) eyes, of which five (56%) achieved 20/200 or better vision. Three eyes that had received laser treatment posterior to areas of retinitis suffered retinal detachment despite this prophylactic treatment. Poor visual outcome resulted from viral infection of the optic nerve or macular involvement, macular hole formation, macular pucker, or hypotony.

Adolescent↗
PubMed1991

Abnormal blood pressure response to exercise in normoalbuminuric insulin dependent diabetic patients.

Eight male normoproteinuric Type I (insulin dependent) diabetic patients and eight age- and sex-matched non-diabetic control subjects were studied for their response to exercise. Systolic blood pressure showed an exaggerated response to exercise in the diabetic group (median 123, range 98-151 mmHg, pre-exercise vs. 187, 163-217 mmHg, immediately post exercise P less than 0.01) compared to the control group (median 112 (100-145) pre-exercise, 153 (138-178) post exercise). Resting noradrenaline levels were lower in the diabetic (D) compared with the control (C) group (D: 1.66, 0.55-3.92 nmol/l vs. C: 2.96, 2.04-4.49 nmol/l, P less than 0.02). Levels rose during exercise by 79% (25-307%) and 43% (4-90%) respectively (NS). Resting urinary sodium was raised in the diabetic group and fell during exercise (P less than 0.05) (D: 146, 74-244 mumol/min, C: 108.5 (83.4-151.0) pre-exercise vs. D: 73, 48-264 mumol/min, C: 81.7 (23.0-92.0) post exercise). Resting atrial natriuretic peptide levels were lower in the diabetic group (D: 10.1, 4.3-16.9 pmol/l vs. C: 16.0, 9.5-22.9 pmol/l, P less than 0.02) and levels rose significantly in both groups during exercise (D: 25.9, 5.2-38.9 pmol/l vs. C: 28.6, 17.3-47.2 pmol/l, P less than 0.05). We conclude that exercise provokes an exaggerated rise in systolic blood pressure and decrease in urinary sodium excretion in normoalbuminuric diabetic patients. These findings may reflect increased sensitivity to the renin-angiotensin-aldosterone system. Reduced atrial natriuretic peptide levels may stimulate sodium retention and increased blood pressure in early diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)

Albuminuria↗