Biomedical subjects
Publications and source records attributed to S D McPherson.
We have written a program in BASIC language which stores, recalls, and manipulates a limited amount of clinical information that we use in teaching and clinical practice. The program runs on an IBM personal computer with Microsoft DOS and BASIC. An illustrative search routine uses simple data simulation of the results of argon laser trabeculoplasty therapy for open-angle glaucoma.
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Our results of anterior vitrectomy in 12 patients with vitreo-corneal touch following cataract extraction, and in three patients with ghost-cell glaucoma due to vitreous hemorrhage were reported. The Machemer vitreous infusion suction cutter was used for pars plana and trans-corneal approaches. Anterior vitrectomy was effective in treating both disorders.
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Filtering blebs following cataract extraction with a limbus based flap may occur approximately 2 to 3% of the time. Difficulty with wearing of contact lens may ensue, the likelihood of infection with postoperative endophthalmitis is remote. A technique for repair by excision of the bleb with a sliding conjunctival flap is described. The results in five patients are reported.
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A new synthetic absorbable suture for ophthalmic surgery--glycolactide--was proved superior to chromic collagen in rupture strength and more predictable absorption time in laboratory and clinical studies. The 8-0 glycolactide showed 30% greater initial strength than 8-0 chromic collagen. One week after implantation in rabbit corneas, the glycolactide retained over 90% of its initial rupture strength, while chromic collagen had lost nearly 50% of its strength. After ten days the strength of the glycolactide fell rapidly. By day 21 it began to be absorbed, completely disappearing by seven weeks. Chromic collagen tended to remain in situ longer, although possessing negligible rupture strength. The two materials were compared in suturing comeoscleral wounds of 45 consecutive patients undergoing routine cataract operation. The glycolactide began to disappear only after the fourth week, completely disappearing after nine weeks. Chromic collagen was more variable, some sutures disappearing as early as the third week, while others remained in place for over 20 weeks. Neither suture material excited reaction in the eyes, and the incidence of complications was low.
A new synthetic absorbable suture, a copolymer of two simple hydroxy acids, glycolic acid and lactic acid, was evaluated in a laboratory and clinical study for its usefulness in ophthalmic surgery. The glycolactide was compared with chromic collagen of similar size. The 8/0 glycolactide showed 30% greater initial strength than 8/0 chromic collagen. Following implantation of the suture in rabbit corneas, the suture was removed at intervals and its rupture strength tested. At the end of 1 week the glycolactide retined over 90% of its initial rupture strength while chromic collagen had lost nearly 50% of its strength. After 10 days the strength of the glycolactide tended to fall rapidly and by day 21 the suture had negligible strength and began to absorb, completely disappearing by 7 weeks. Chromic collagen tended to remain in situ for many weeks although possessing negligible rupture strength. The 8/0 glycolactide was compared with 8/0 chromic collagen in suturing corneoscleral wounds of 45 consecutive patients undergoing routine cataract surgery. Handling qualities were judged and the eyes followed post-operatively to ascertain reaction to the sutures and time of final disappearance of the sutures from the eyes. The glycolactide showed no tendency to disappear from the wounds until after the fourth week. By the end of 9 weeks all the glycolactide sutures had disappeared. Chromic collagen, on the other hand, was more variable, some sutures disappearing as early as the third week while others remained in place essentially unchanged for more than 20 weeks. Neither glycolactide nor chromic collagen showed any tendency to excite reaction in the eyes and the incidence of complications was low.
A technique for combined trabeculotomy and cataract extraction is described. The application of the combined procedure in 17 eyes with chronic glaucoma and immature senile cataract is described. The results were uniformly good, and only one patient required further treatment for glaucoma.
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Two cases of posterior form sympathetic ophthalmia are presented. The histologic abnormalities in one of them are described. Based on findings in these two cases and other descriptions of posterior form sympathetic ophthalmia in the literature, the authors conclude that except for absence of anterior uveal tract involvement, there is no histopathologic difference between posterior form sympathetic ophthalmia and classical sympathetic ophthalmia. Although there is disagreement in the literature, the authors also conclude that the therapy and prognosis of posterior form sympathetic ophthalmia does not differ from that of classical sympathetic ophthalmia.
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