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Biomedical subjects

J C Jin

Publications and source records attributed to J C Jin.

13 recordsLinked to original sources
PubMed1992

An analysis of intraocular lens exchange.

We present an analysis of 101 eyes of 98 consecutive patients who underwent intraocular lens (IOL) exchange. The period of follow up ranged from 6 to 71 months (mean, 23 months). Bullous keratopathy was the leading (86.7%) indication for IOL exchange in 45 eyes that had combined penetrating keratoplasty (PKP) and IOL exchange (PKP group). Lens dislocation (36%) and incorrect power (25%) were the most frequent indications for IOL exchange without PKP (56 eyes) (NPKP group). A final visual acuity of 20/40 or better was achieved in 50.5% of the 101 eyes, with 88% having two lines of improvement or remaining within one line of the pre-exchange acuity. The geometric mean visual acuity was significantly improved, from 20/273 preoperatively to 20/125 postoperatively, in the PKP group (P less than .001), and from 20/61 to 20/43 in the NPKP group (P = .001). The main reason for vision less than 20/200 in the 23 eyes in the PKP group was glaucoma (nine eyes) and bullous keratopathy (eight eyes). In the NPKP group, seven eyes (four due to cystoid macular edema, CME) had a visual acuity less than 20/200. Posterior chamber (PC) IOL implantation was associated with significantly better visual acuity than anterior chamber (AC) IOL implantation when performed at IOL exchange (P = .004). The most common complications encountered with IOL exchange were CME (17.8%), hyphema (15.8%), glaucoma (10.9%) and PC opacity (8.9%).

Aged↗
PubMed1991

The physiologic characteristics of relative pupillary block.

In biometric photographs of 13 patients, we quantified the iris contour in eyes with central anterior chamber depths ranging from 1.9 to 3.4 mm (epithelium to lens surface). This actual profile was compared to that predicted by a theoretical analysis of the forces acting on the iris. The average discrepancy between the calculated actual and the theoretically predicted iris position was only -0.01 to +0.03 mm. The close agreement validates the model under normal conditions and in the presence of relative (nonsynechial) pupillary block. The theoretical iris shape may not occur under conditions that violate the underlying physical assumptions of the mathematical model, such as when iridectomy eliminates the pressure difference between the anterior and posterior chamber or when synechiae introduce additional forces on the iris other than the ones included in the analysis.

Anterior Chamber↗
PubMed1991

Comparison of a 3- and 6-mm incision in combined phacoemulsification and trabeculectomy.

We studied 216 eyes of 160 patients who underwent combined phacoemulsification and posterior chamber intraocular lens implantation with trabeculectomy. The mean follow-up was 18.7 months, with a minimum follow-up of six months. To assess the safety and efficacy of a recently developed 3-mm incision procedure with foldable intraocular lens implantation (phacotrabeculectomy), we compared 104 eyes subjected to this procedure with 112 eyes subjected to a 6-mm procedure at different follow-up periods. Intraocular pressure control (less than 21 mm Hg) was attained in 44 of 46 eyes (96%) in the 3-mm group and 71 of 76 eyes (93%) in the 6-mm group at one year postoperatively. Visual acuity of 20/40 or better was attained in 40 of 46 eyes (87%) in the 3-mm group and 66 of 76 eyes (87%) in the 6-mm group. The incidence of postoperative complication was significantly lower (P less than .001) and visual acuity in the early postoperative period was significantly better (P less than .01) in the 3-mm incision group than in the comparison group.

Adult↗
PubMed1991

Effect of short-term intraocular pressure elevation on the rabbit electroretinogram.

Pattern electroretinograms (PERGs), with a presumed ganglion cell origin, and oscillatory potentials (OPs), with a presumed inner retinal origin, are reduced in glaucoma. Flash ERGs are reduced at intraocular pressures (IOPs) greater than 60 mm Hg. A study was designed to investigate the time-course of change in PERGs, OPs, and flash ERGs after increasing the IOP of ten rabbit eyes to 35-45 mm Hg by using a suction-cup apparatus. Although flash ERG b-wave amplitude was unchanged (P = 0.32), PERGs were reduced (P less than 0.001) immediately after IOP elevation, as were OPs (P = 0.03). Both PERG and OP amplitudes returned to normal immediately after normal IOP was restored. This study showed that the rabbit is a suitable model for studying PERGs. It also suggested that moderate IOP elevation for 10 min reversibly impaired ganglion cell and inner retinal function in the rabbit, although more external function was unchanged.

Animals↗
PubMed1990

The effect of iridotomy on iris contour.

With a recently developed technique for quantifying the geometry of the anterior chamber in optical cross section (slit-lamp photography using the Scheimpflug principle and computer correction for the optical effects of the cornea), we studied the iris contour before and after iridotomy in six patients with narrow anterior chamber angles and angle-closure glaucoma. Before iridotomy, the iris contour was convex anteriorly in all meridians. After iridotomy, the anterior lens surface position did not change perceptibly. The iris at the pupil margin settled backward onto the lens surface, no longer held forward by the narrow stream of aqueous passing from the posterior chamber to the anterior chamber. Next to the pupil there was often a perceptible mound, presumably representing the iris sphincter. From the point of support by the lens to the root of the iris, the contour of the iris surface was a straight line, except for the surface irregularities. The deepening of the anterior chamber at each point was the difference between the convex contour before iridotomy and the straight line after iridotomy.

Glaucoma↗
PubMed1990

Laser and unsutured sclerotomy in nanophthalmos.

Among 30 eyes with nanophthalmos, 21 had angle-closure glaucoma and two had open-angle glaucoma associated with pseudoexfoliation of the lens capsule. Laser iridotomies, sometimes combined with laser iridoplasty, were sufficient to control, or to allow medical control of, the glaucoma in 15 of 18 eyes. Four eyes with uveal effusion underwent an unsutured sclerotomy or sclerectomy, and all had resolution of the choroidal detachment within two weeks. Cataract extraction improved the vision in seven of nine eyes. Previous or simultaneous sclerotomy or sclerectomy was performed on all nine eyes that underwent cataract extraction and in two eyes at the time of glaucoma surgery; no eye had postoperative uveal effusion or other major complications. Laser iridotomy and iridoplasty, sometimes with supplemental medical therapy, are often sufficient in the treatment of angle-closure glaucoma in nanophthalmos and are safer than surgery. Nanophthalmic uveal effusion can be prevented or treated with an unsutured sclerotomy or sclerectomy.

Adolescent↗
PubMed1990

Visual function deficits in glaucoma. Electroretinogram pattern and luminance nonlinearities.

The pattern electroretinogram is abnormal in glaucoma. Part of the pattern electroretinogram may be attributed to the summation of responses to luminance increases and decreases (nonlinear luminance responses). We conducted a study to investigate the effect of glaucoma on the pattern electroretinogram component waves and to determine if the flicker electroretinogram nonlinear components are abnormal in glaucoma. We tested 35 subjects in two replications of four conditions: 10- and 20-Hz flicker, and 4- and 10-Hz pattern reversal. Only the even harmonics were recorded. The patients with glaucoma had reduced electroretinogram amplitudes for all measures relative to the normal subjects. Electroretinogram amplitudes of those suspected of having glaucoma were intermediate. The greatest amplitude reductions were for the 10-Hz flicker electroretinogram and the 4-Hz pattern electroretinogram. These results confirm pattern electroretinogram abnormalities and reveal flicker electroretinogram abnormalities in glaucoma.

Adult↗
PubMed1979

In vitro synthesis of humoral factors (immunoglobulins and complement) in lesional skin of leprosy patients.

An in vitro culture technique was used to demonstrate the synthesis of immunoglobulins and complement in lesional skin of patients representing the entire clinico-histopathological spectrum of leprosy. The results indicate that immunoglobulin G is produced in different amounts in the various forms of leprosy. Classification of the patients according to the three main groups shows that a small amount of immunoglobulin G synthesis occurred in tuberculoid leprosy, a distinct amount occurred in borderline leprosy, and large amount occurred in lepromatous leprosy. Contrary to expectation, synthesis of C3 was found only in some of the cultures of these three forms of leprosy. The function of the locally synthesized immunoglobulin G and the findings concerning C3 synthesis are discussed.

Adolescent↗
PubMedDate not supplied

Circular and interrupted suture technique for correction of hyperopia following radial keratotomy.

BACKGROUND: Hyperopia is a possible complication following radial keratotomy. In this article, we describe a circular and interrupted corneal compression suture technique for the correction of hyperopia induced by radial keratotomy. METHODS: A retrospective study was performed to evaluate the effectiveness of this procedure in nine consecutive patients. RESULTS: The procedure achieved an average of -1.70 diopters change in spherical equivalent refraction. This accounted for an overall correction of 68% of the hyperopia caused by radial keratotomy after a minimum 3-month follow up. Seven of nine eyes (78%) were within 1.00 D of emmetropia after surgery. Uncorrected visual acuity of 20/40 or better was present in only two eyes (22%) preoperatively, and nine eyes (100%), after the corneal suturing procedure. The mean improvement of uncorrected visual acuity was 4.0 Snellen lines (P = .0004). All patients were pleased with their visual outcomes. CONCLUSIONS: We found that this technique is an easy, safe, and reasonably successful treatment for radial keratotomy overcorrection.

Adult↗