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The authors demonstrate the results of pars plana vitrectomy in idiopathic macular holes in a group of their patients where, based on postoperative results, they draw attention to the importance of early diagnosis of the disease and indication of surgery.
The effects of an incision through the pars plana ciliaris for open-sky subtotal vitrectomy were evaluated in four groups of monkeys, with incisions ranging from 170 degrees to 240 degrees. The nasal long ciliary artery and nerve and the anterior ciliary arteries from the inferior and medial recti were left intact in all cases. Follow-up observation ranging from three to 24 months indicates that the 170 degrees incision and the longer incisions in which the temporal ciliary artery and nerve were sacrificed do not cause severe anterior segment necrosis. The advantages of the incision through the pars plana ciliaris are (1) easier approach to the vitreous cavity, (2) preservation of the crystalline lens and an intact iris, and (3) circumvention of the corneal and chamber angle complications sometimes associated with the transcorneal approach.
Six eyes, four obtained at autopsy and two enucleated for neovascular glaucoma, were studied histopathologically between one week and 3 1/2 years after pars plana vitrectomy (some combined with lensectomy) for proliferative diabetic retinopathy. Fibrovascular proliferation at the sclerotomy site was minimal. Lensectomy through the pars plana proved to be quite complete. A cyclitic membrane was found in eyes with postoperative rubeosis irides. Excision of the vitreous from the posterior part of the vitreous cavity was quite complete except for remnants of stalks and membranes on the retinal surface.
We performed 400 consecutive pars plana vitrectomies, using the vitrophage. Most patients (68%) showed some degree of visual improvement; only 8% had a decline in visual acuity postoperatively. The major operative complications were controllable bleeding from iris vessels and intravitreal stalks (19%) and retinal tears (2%). No retinal dialysis was noted. The major, early postoperative complications were related to corneal decompensation in 38% of the cases; this persisted beyond two weeks in only 7%. Increased intraocular pressure occurred in 19% and postoperative rubeosis iridis developed in 10% of the diabetic patients. Complications related to rebleeding occurred in 18% of the diabetic patients within the first two weeks, and an additional 9% had late rebleeding. Less frequent complications included one case of endophthalmitis, late retinal detachment in 5%, and phthisis bulbi in 2% of all cases. All complications were considerably more frequent and severe in the diabetic population.
Pars plana vitrectomy was used to treat 134 consecutive eyes with complications resulting from proliferative diabetic retinopathy, including nonabsorbing vitreous hemorrhage, recent traction and rhegmatogenous retinal detachment, progressive fibrovascular proliferation, and early rubeosis iridis with recent vitreous hemorrhage. Vision improved after surgery in 65% of the eyes, was unchanged in 16%, and decreased after surgery in 19%. In 24% of the successful cases, vision of 20/50 or better was achieved. When all posterior cortical vitreous was removed, no preretinal fibrovascular growth occurred after surgery. Nonatrophic epiretinal fibrovascular membranes that were not removed usually underwent centripetal contraction after surgery, causing tangential traction on the adjacent retina. Rubeosis iridis was the most common postoperative complication in otherwise successful cases, and rubeosis underwent regression after scatter retinal photocoagulation in some eyes.
Combined lensectomy-vitrectomy was performed on 13 patients (15 eyes) with complicated cataracts from uveitis. Preoperative visual acuities were 20/200 or less for at least one year. The postoperative follow-up period averaged 10.5 months with visual acuities of 20/25 or better in eight eyes, 20/70 in two eyes, and 20/100 to 20/400 in five eyes. The primary cause of decreased vision postoperatively was cystoid macular edema with frequently associated optic disc edema.
A Corynebacterium sp was isolated from the vitreous humor under aseptic conditions on two separate occasions from a patient with endophthalmitis resulting from a penetrating injury by a metallic foreign body. The metallic foreign body was removed during a pars plana lensectomy and anterior vitrectomy procedure; intravitreously injected methicillin sodium, gentamicin sulfate, and dexamethasone sodium phosphate gave a functional visual result. Intravitreous inoculation of rabbits with the Corynebacterium isolate produced an endophthalmitis similar to that produced in the patient, and subsequent cultures from the vitreous of the inoculated rabbits grew the same Corynebacterium sp. To our knowledge, this is the first reported case of endophthalmitis in which a Corynebacterium sp was documented by intraocular culture.
In a series of 30 vitrectomy patients, postoperative corneal complications developed in 14 (47%). Thirteen (92%) of the 14 patients with complications were diabetic. Other factors that were positively correlated with the development of corneal complications included decreased corneal sensitivity, intraoperative lensectomy, and intraoperative epithelial debridement. The corneal complications involved the epithelium in 11 (78%) of the 14 complicated cases, with involvement of the endothelium (as manifested by stromal edema) in five (35%) cases. The diabetic human corneal epithelium contains considerable levels of sorbitol and fructose, which indicates the probable presence of the sorbitol pathway. As in the lens, this pathway may lead to osmotic changes that make the diabetic corneal epithelium more vulnerable to damage intraoperatively. Postoperatively, reepithelialization is delayed because of a probable failure of adhesion of cells to the underlying basement membrane.
A new prismatic type of lens enables a more peripheral view of the vitreous cavity. The surface in contact with the cornea is concave. The opposite surface is plano but inclined to produce a prismatic effect of 15 degrees or 25 degrees. A cannula attached to the lens provides corneal irrigation. Although this lens was originally designed for vitrectomy use, it is also useful for diagnostic biomicroscopy of the vitreous and fundus in the office.
Four patients with vitreous opacity characterized by veil-like membranes with precipitates of presumed inflammatory cells had visual acuities in the affected eye of hand movements only, 20/200, 20/400, and 20/400 over a period of six months or longer. A history compatible with episodes of inflammation secondary to toxoplasmosis and a chorioretinal scar compatible with toxoplasmosis in the involved or opposite eye was present in each patient. Pars plana vitrectomy (with lensectomy in three of the four cases) has afforded information in regard to preoperative and postoperative management of such patients, as well as postoperative results.
A sustained-grip, pressure-release, cross-action forceps was developed to obtain firm and steady holding of the contact lens during vitrectomy surgery. For use in conjunction with the forceps, a plano-concave fundus contact lens has been modified by having a circular groove cut around it.
A prospective, randomized, double-blind study showed that glutathione-bicarbonate-Ringer's solution (BSS Plus) caused significantly less corneal swelling on the first postoperative day after pars plana vitrectomy than did lactated Ringer's solution. By the seventh postoperative day, no difference was seen between the two solutions. We found no correlation between the increase in corneal thickness and either the duration of intraocular irrigation or the volume of solution used or the presence or absence of the lens. No persistent corneal complications were seen.
Combined illumination-irrigation 20-gauge probes that couple to the fiber-optic source on a vitrectomy machine (Ocutome) have performed well during surgery in selected cases.
Electron microscopic analysis of intravitreal strands produced by the injection of autogenous fibroblasts showed thin, immature collagen after two weeks and the mature banded variety after four weeks. With the use of this intravitreal strand model, it was found that highly purified bacterial collagenase caused extensive digestion of scar tissue after incubation periods of 10, 15, and 30 minutes. There was no morphologic damage to cicatricial cellular elements or to the inner limiting membrane of the retina. A 45-minute exposure of retinas previously injured by photocoagulation to collagenase also did not result in morphologic evidence of damage. The use of collagenase as an adjunct to vitrectomy in cases of extreme vitreal scarring or retinal traction may decrease the complication rate of a procedure that is still extremely hazardous.
Pars plana vitrectomy was carried out in 140 patients with useful to excellent visual acuity associated with elevated proliferative diabetic retinopathy. A substantial reduction in the incidence of traction retinal detachment occurred and a significant improvement in visual prognosis was achieved.
We have designed a self-retaining iris speculum for use in open-sky vitrectomy. This speculum retracts the iris away from the central field and thus allows the surgeon better visibility and less reliance on an assistant's help for retraction. The possibility of iris laceration and dialysis with excessive bleeding, as sometimes seen with other forms of iris retraction, can be prevented.
The level of final visual acuity results and the prognostic factors predictive of the level were analyzed in 360 eyes that had pars plana vitrectomy for diabetic traction retinal detachment of the macula. Fifty-nine percent of the eyes had improved visual acuity on final examination. The percentage of eyes that achieved a final visual acuity of 20/100 or better and the percentage that achieved 5/200 or better increased from 21% to 36% and from 57% to 72%, respectively, during the study. Preoperative factors associated with a favorable visual prognosis were a visual acuity of 5/200 or better, the absence of iris neovascularization, a clear crystalline lens or only minimal cataract formation, clear media or only mild vitreous hemorrhage, panretinal photocoagulation of at least one fourth of the retina, and the absence of severe preoperative retinal neovascularization. Intraoperative factors associated with a favorable visual prognosis include the avoidance of performing a lensectomy, the absence of iatrogenic retinal breaks, and the avoidance of using intraocular gas bubbles.
The results of pars plana vitrectomy for diabetic traction-rhegmatogenous retinal detachment were analyzed in 172 eyes, and the factors associated with a final visual acuity of 5/200 or better were identified. Forty-eight percent of eyes had improved vision on final examination. The proportion of eyes with a final visual acuity of 20/100 or better and 5/200 or better remained virtually the same during the ten-year study interval. Preoperative factors associated with a visual acuity of 5/200 or better were a preoperative visual acuity of 5/200 or better, the absence of iris neovascularization, and the absence of retinal detachment involving the macula. The intraoperative factor associated with a final visual acuity of 5/200 or better was the absence of iatrogenic retinal breaks.