A. Rodman Irvine

Light-Induced Maculopathy from the Operating Microscope in Extracapsular Cataract Extraction and Intraocular Lens Implantation

A characteristic macular lesion has been noted in six patients who underwent extracapsular cataract extraction with posterior chamber lens implantation. The lesion appeared similar to that which other investigators have produced in monkeys as a response to the coaxial illumination of the operating microscope. On the first or second postoperative day, the lesion appeared as an oval area of mild yellow-white discoloration of the retina; gradually it developed mottled pigmentation over the next few weeks. The pigmentary changes were often subtle, but fluorescein angiography revealed a characteristic sharply circumscribed lesion. In most of our patients the lesion was just above or below the foveola, so that central vision returned to normal, but a paracentral scotoma was present. These findings should encourage the clinician to heed the warnings of those laboratory studies which have shown the phototoxic potential of the operation microscopes unfiltered coaxial illumination and force us to re-examine our filters and operating techniques.

The pathogenesis of retinal detachment with morning glory disc and optic pit.

A child with nonrhegmatogenous retinal detachment associated with morning glory disc underwent first a vitrectomy and then, some months later, an optic nerve sheath fenestration. The latter procedure led to retinal reattachment. It also produced a biopsy specimen that confirmed the perineural hemiation of poorly differentiated retinal tissue in this condition, similar to that in congenital pit of the optic nerve. It demonstrated continuity of the vitreous cavity with the perineural space, both histologically and by the fact that gas injected through the pars plana into the vitreous cavity bubbled out the window in the optic nerve sheath. The authors suggest that morning glory disc and optic pit share similar anatomic features, differing more in degree than in kind, and that the porous nature of the poorly differentiated tissue herniated around the optic nerve into thesubarachnoid space in these conditions makes several sources of subretinal fluid possible.

Radiation retinopathy as an experimental model for ischemic proliferative retinopathy and rubeosis iridis

We produced radiation retinopathy in capuchin monkeys and studied them with fluorescein angiography and light and electron microscopy. The animals were followed up from ten days to 3 1/2 years after radiation in order to determine whether this could provide an experimental model for other chronic ischemic-proliferative retinopathies, such as diabetes. The first change detected after radiation was the focal loss of capillary endothelial cells and pericytes. As the areas of acellular capillaries became confluent, cotton-wool spots became visible ophthalmoscopically. These increased in number and then faded away, leaving large areas of retinal capillary perfusion. Histologic studies showed occlusion first of the deeper, smaller retinal vessels and then gradually of the larger vessels. Intraretinal neovascularization as well as apparent recanalization then developed, but no new vessels extended through the internal limiting lamina into the vitreous. Rubeosis iridis with neovascular glaucoma developed 2 1/2 to 3 1/2 years postirradiation, and vitreous aspirate demonstrated a high level of angiogenic factor.

Retinal Phototoxicity from the Operating Microscope: The Role of Inspired Oxygen

The effect of the inspired oxygen concentration (FIO2) on the production of retinal phototoxicity by the operating microscope was studied in phakic rhesus monkeys. One eye of each monkey was exposed to light under conditions of 99% FIO2, and the other eye was exposed under 21% oxygen (O2). Three of four locations on each retina were exposed to light for durations varying from 1 1/2 to 20 minutes per exposure. Fundus photographs and fluorescein angiograms were obtained 24 to 72 hours after exposure. Animals were euthanatized for analysis of retinal histopathology at intervals from 2 weeks to 8 months after light exposure. Retinal phototoxic lesions were produced after an average of 5 minutes of light exposure under both 21 and 99% O2. O2 potentiated the light damage both clinically and histologically. Under both conditions, lesion size was directly related to the duration of light exposure (P less than 0.005). Lesions near threshold produced with 99% FIO2 were 1.6 to 6.9 (mean, 2.9) times larger than the corresponding lesions formed with 21% FIO2. Histologic damage was likewise more severe in lesions produced under high O2 conditions. Retinal repair occurred in lesions produced under high and low O2 conditions. Photoreceptor regeneration was nearly complete by 18 weeks, whereas retinal pigment epithelial (RPE) recovery lagged up to 1 1/2 months. The results of this study have important implications for clinical practice: the operating microscope can produce retinal phototoxicity rapidly, and O2 administered during ophthalmic procedures may potentiate the damage if appropriate precautions are not taken.

Vitrectomy in Infants and Children with Retinal Detachments Caused by Cicatricial Retrolental Fibroplasia

Four infants and one child with retinal detachments from cicatricial retrolental fibroplasia involving traction judged too severe to be relieved by scleral buckling alone underwent lensectomy and vitrectomy. Three retinas were successfully reattached. Because of the incomplete development of the pars plana in infants and the manner in which peripheral retina is pulled anteriorly to a position near or in contact with the posterior lens capsule, entry through the pars plana can create iatrogenic tears in the peripheral retina or introduction of irrigation fluid under the retina. Our experience has shown that a small contact lens makes it possible to work in the posterior vitreous cavity through the limbal approach in these infants. The circumferential traction produced by the ring of fibrovascular proliferation behind the lens can be relieved and tractional bands running forward from the posterior pole can be cut. Fibrovascular proliferative tissue lying on the posterior pole, however, proved resistant to membrane peeling or dissection, and its severity seemed to determine the success or failure of the surgery.

Recurrent Amyloid Involvement in the Vitreous Body After Vitrectomy

A patient with vitreous opacification due to primary familial amyloidosis underwent bilateral vitrectomy via the pars plana with excellent visual results. Two and one half years later opacification of the vitreous body recurred in the retrolental area bilaterally, necessitating a repeat vitrectomy in the left eye. This opacity was successfully removed from the posterior surface of the lens without apparent damage to the lens.

Correlation between Degree of Malignancy and the Radioactive Phosphorus Uptake Test in Ocular Melanomas

Twenty-nine patients who had undergone enucleation for ocular malignant melanoma were studied. The results of the radioactive phosphorus uptake (32P) tests were correlated with histopathologic observations. There was a positive correlation between the 32P test results and the histologic degree of malignancy. Mixed cell melanomas were more frequent in the patients ranked with higher 32P test results. Spindle cell melanomas occurred more frequently in patients with lower 32P test results. Mitoses per field and degree of malignancy correlated positively with 32P test results when ranked in a masked manner by two ocular pathologists. Tumor volume and clinical factors did not correlate with the 32P test results. While patients with mixed cell melanomas had higher mean 32P test results than those with spindle cell melanomas, a large variance was noted. Because of this the 32P test is unreliable in predicting the histopathology of a tumor in individual cases.

An ultrasonographic study of early buckle height after sponge explants.

A series of ten consecutive patients operated on with episcleral sponge explants underwent serial B-scan ultrasonographic examinations between three days and 12 months postoperatively. The amount of indentation of the globe was surprisingly high, with a 5-mm sponge often producing 4 to 4.5 mm of indentation. The amount of indentation ranged from 3.25 to 4.5 mm (median, 4 mm). This indentation decreased only slowly during the postoperative period, and three to 12 months postoperatively most patients still maintained 75% or more of their initial buckle height.

Pupillary membrane excision and anterior vitrectomy in eyes after uveitis.

Three patients with uveitis and dense pupillary membranes, total synechial closure of the angle, and low or normal pressure, underwent membranectomy and anterior vitrectomy via a limbal approach using scissors and a vitrectomy instrument. Postoperatively all regained useful vision that has been maintained for over two years despite the persistence of angle closure in all cases and severe hypotony in two.

The Diagnoses Most Commonly Missed by Ophthalmologists Referring Patients for Fluorescein Angiography

A tally of misdiagnoses in patients referred to a fluorescein angiography service disclosed that three conditions made up the majority of all misdiagnoses. These conditions were chronic branch retinal vein obstruction, old or chronic central serous choroidopathy, and retinal arterial macroaneurysms with subretinal or subhyaloid hemorrhage. These three conditions proved to be talented mimics with a wide variety of presentations.