Retinopathy of prematurity: incidence and risk factors.

A high incidence of retinopathy of prematurity (ROP) was found in the very low-birth-weight infants discharged from the neonatal intensive care unit during the years 1977 to 1980, in spite of frequent monitoring of oxygen use. Although the yearly incidence of ROP in infants weighing less than 1,500 g varied between 35% to 36%, none were blind. The medical records of 65 infants with a birth weight between 501 and 1,250 g; surviving in 1979 to 1980, were reviewed in order to find risk factors for ROP. There were no significant differences between the 34 infants with ROP and the 31 infants who did not have ROP in mean birth weight or mean gestational age. Of 32 possible risk factors examined, the factors significantly associated with ROP were: apnea with mask and bag ventilation; prolonged parenteral nutrition; number of blood transfusions; and episodes of hypoxemia, hypercarbia, and hypocarbia. A highly significant association between hypocarbia and the development of severe ROP was found.

Clinical method for measurement of light backscattering from the in vivo human lens.

A simple clinical method for measurement of light backscatter from defined regions of the lens in vivo is described. Light scattering was quantitated in 168 lenses of 85 "normal" subjects spanning 8 decades of life. The results indicate that light scatter from the anterior capsule does not change with age. The light scatter from the anterior cortex is quite significant even in young lenses and gradually increases with age. The backscatter in the nuclear region is minimal in young eyes, increasing gradually up to the age of 40, after which it exhibits a sharp increase.

Inhibition of macrophage migration by choroidal malignant melanoma-associated antigens in patients with unveal melanoma.

The specific cell-mediated immunity of the lymphocytes of eight patients with choriodal malignant melanoma (MM) to four extracts of choroidal MM-associated antigens was tested with the aid of the MIF technique. Seven of the patients with choroidal MM responded to at least one of the four extracts used, whereas patients with choroidal nevus or carcinoma as well as healthy controls did not respond to any of the MM choroidal extracts. There was no response to iris extracts obtained from the enucleated eyes with MM in any of the subjects tested.

Fuch's heterochromic iridocyclitis: an electron microscopic study of the iris.

The irides of two patients with Fuch's heterochromic iridocyclitis were investigated by electron microscopy. The main findings were abnormal melanocytes with relatively few, small, and at times immature melanin granules, abundance of plasma cells, and membranous degeneration of nerve fibers. The defective melanin production may be due to abnormal adrenergic innervation, either primary or secondary to the inflammatory process. The cause for this inflammatory reaction was not evident in this study.

Oxygen-induced retinopathy in newborn kittens. A model for ischemic vasoproliferative retinopathy.

Fourteen kittens were reared in 80% oxygen for 65-72 hr, after which they were returned to room air. At that time, funduscopic examination of all the kittens showed complete obliteration of the retinal vasculature and even optic disc vessels. In the following 18-21 days, florid preretinal new vessels were found growing into the vitreous from the revascularized retina and from the optic disc itself. Subsequent histologic examinations confirmed the above clinical findings and reinforced the authors to suggest this animal model as a future research tool for ischemic vasoproliferative retinopathy, rather than a model for retinopathy of prematurity (ROP). The similarities and dissimilarities between this animal model and the human ischemic retinal disease are discussed.

The retinal effects of copper vapor laser exposure.

The copper vapor laser is a pulsed gas laser which emits energy in two wavelengths simultaneously: 510.6 nm (green) and 578.2 nm (yellow). Each pulse has a duration of 15 nsec, maximal energy of 3 mJ and a peak power of more than 100 kW. It is a variably high repetition rate laser, in the range between 1 kHz and more than 20 kHz. We studied its interaction with the rabbit retina, while using two different repetition rates, 4 kHz and 18 kHz. The histological analysis of the lesion produced by 4 kHz repetition rate showed undesired retinal effects, similar to those caused by other pulsed lasers. On the other hand, the histological examination of the lesion produced by the 18 kHz repetition rate showed a desired coagulation effect, limited to the outer retinal layers, and comparable to a lesion produced by a continuous wave (CW) laser.

The effect of sodium hyaluronate on the corneal epithelium. An ultrastructural study.

The effect of sodium hyaluronate (NaHa) 1% and 0.1% was studied on 14-day chick embryo corneal epithelium by scanning electron microscopy. It was found that NaHa 1% or 0.1% had no toxic effects on the chick corneal epithelium and the normal architecture of the cells and the morphology of the microvilli was well preserved. A combination of NaHa 0.1% and benzalkonium chloride (BAK) 0.01% reduced the toxic effect of BAK on the surface corneal epithelium. NaHa 0.1% provided a better protection of the corneal epithelium against dryness than hydroxyethylcellulose (HEC) 0.1% or phosphate buffer saline (PBS).

Laser iridotomy in closed-angle glaucoma.

An argon laser iridotomy was performed on 53 eyes of 34 patients with closed-angle glaucoma. Technically, all of the iridotomies were successful. Blue irides were more resistant to treatment than brown irides. The iridotomies were performed with high energy of 2 W and a very short exposure time of 0.01 to 0.04 s, thus minimizing thermal damage to adjacent tissues. Patients with narrow angles who underwent preventive laser irodotomy benefited most from the procedure, and all the eyes of this group maintained a normal intraocular pressure (IOP) after the iridotomy. Of the 20 eyes with acute angle-closure glaucoma, 17 maintained a normal IOP after iridotomy, and only three were resistant to this treatment, calling for filtering operations later. The IOP of eyes with chronic closed-angle glaucoma did not change after the procedure, and the iridocorneal angles remained practically the same. Argon laser iridotomy by this technique is highly recommended as the procedure of choice for eyes with acute angle-closure glaucoma and for preventive iridotomy in the fellow eye. The procedure is simple, is performed in the outpatient clinic, and engenders no major complications.

Retinal hemorrhages in the newborn following labor induced by oxytocin or dinoprostone.

We examined the fundi of 100 newborns following labor induced by intravenous oxytocin or by oral dinoprostone. Retinal hemorrhage was observed in 40% of neonates in the dinoprostone treatment group, as compared with 28% in the oxytocin treatment group. The accumulation of prostaglandins in the fetal circulation may be responsible for the hemorrhages, which clear spontaneously once the noxious agent is metabolized. Other organ systems must be carefully examined in the neonate to detect other possible untoward effects.

Retinopathy of prematurity.

Over the last decade major advances have been made in the understanding of the pathogenesis and evolution of retinopathy of prematurity (ROP). The increased survival of very small premature infants in modern neonatal intensive care units has led to the resurgence of this potentially blinding disease. ROP appears to be a multifactorial disease, the prevention of which is probably impossible even now, with the most accurate methods of blood gas monitoring and oxygen restriction. In addition to oxygen, there are a number of significant risk factors, such as birth weight and gestational age, ventilator hours, hyper and hypocarbia, hypoxia and acidosis, xanthine therapy and probably bright light. Current data suggest that the level of antioxidants in the immature retina is relatively low and therefore oxygen radicals which accumulate in the preterm baby's retina may play an important role in the pathogenesis of ROP. The treatment of the disease in both its "active" and "cicatricial" stages emphasizes the need for a new classification which could serve as a common international language through which results may be compared. Vitamin E was suggested in some studies to be helpful in preventing the severe stages of the disease, but its efficacy has yet to be proved. Treatment modalities such as photocoagulation, cryotherapy and vitrectomy are being tried as a means of therapy in the more advanced stages of the disease. Preliminary results of a large multicenter study support the efficacy of cryotherapy.

Amaurosis fugax at downward gaze.

A 54-year-old man with a past history of hypertension, diabetes mellitus, hypercholesterolemia and two myocardial infarctions presented with repeated attacks of amaurosis fugax in the right eye. The fact that the amaurosis occurred only on downward gaze is sufficient evidence to exclude carotid atheromatous disease and to imply an orbital etiology.

Treatment of macular subretinal neovascularization with the red-light krypton laser in presumed ocular histoplasmosis syndrome.

A patient with presumed ocular histoplasmosis and decreased visual acuity in one eye had subretinal neovascularization and retinal hemorrhage in the macular area. Argon-laser treatment to eradicate the subretinal neovascular membrane was contraindicated because of the proximity of the hemorrhagic lesion to the fovea. We used a red-light krypton laser (647 nm) because the light is not absorbed by the hemoglobin in the retinal hemorrhage or by the macular luteal pigment (xanthophyll), and because it is transmitted into the choroid, allowing treatment within the macular zone with less damage to the internal retinal elements. After treatment, the subretinal neovascular membrane completely disappeared and the macular hemorrhage cleared. To the best of our knowledge, this is the first time that a histoplasmic macular subretinal neovascular membrane has been treated with the red-light krypton laser.

Surgical management of retinal detachment without cryopexy.

A clinical study of eyes with rhegmatogenous retinal detachment compared the reattachment rate in two groups of eyes: in the control group, cryopexy was applied over the retinal breaks during surgery; in the test group, cryopexy was not applied. There was a similar rate of retinal reattachment in the two groups in the immediate postoperative period. However, during the long follow-up period (36 months) there was a considerable difference in the two groups. Eyes that had undergone cryopexy had a lower rate of redetachment than eyes that had not. The rate of operative and postoperative complications was low in both groups, except for periretinal proliferation, which was more frequent in the test group. These results suggest that cryopexy may lower the incidence of redetachment after retinal detachment surgery.

Corneal metastatic calcification in Werner's syndrome.

We examined twin sisters with a clinical picture typical of Werner's syndrome. Both had undergone bilateral cataract extraction, one at 39 and one at 36 years of age, and had subsequently developed bilateral corneal metastatic calcification within a period of one to two years. In one twin, this keratopathy was associated with hypercalcemia. Each of the twins underwent penetrating keratoplasty in one eye, which was complicated by recurrence of metastatic calcification in a previously normal and clear corneal graft.

Fluorescein angiography with an optimized filter combination.

The transmission characteristics of a new filter combination for fluorescein angiography were selected on the basis of in vivo measurements of the excitation and emission spectra of fluorescein dye during its transit in the fundus. This combination of filters was characterized by separation of 530 nm between the spectral ranges of transmission of the excitation and barrier filters. In the standard filter combinations this separation is at about 495 nm. Compared to the standard filters, the new filters enhanced the film exposure for all sites of the fundus, especially for the macular area and choroidal fluorescence. There was an improvement in demonstration of the choroidal vasculature, especially in the macular area, and better visibility of retinal detail in the macular area, but a slight decrease in contrast of the retinal vessels outside the macular region. Improved visibility of the fundus for the observer and reduction of scattering in the ocular media of older subjects improved the overall quality of angiograms made with the new filters.

Narrow-band (540NM) green-light stereoscopic photography of the surface details of the peripapillary retina.

We used narrow-band (540-nm) green-light stereoscopic fundus photography to study the surface details of the peripapillary retina in 14 patients. Each photograph was divided into four areas; the papillomacular bundle, the upper arcuate bundle, the lower arcuate bundle, and the nasal sectorial fibers. We scored each area on a scale of 0 (normal) to 3 (total loss of nerve fiber layer), and compared these scores to those obtained by testing the corresponding visual fields. The scores were the same in 88 of 111 comparisons; the retinal scores were higher in 17 comparisons and the visual field scores were higher in six comparisons. This photographic technique makes the nerve fiber layer easier to see and evaluate and the detection of defects becomes less difficult.

Autosomal dominant inheritance of retinoschisis.

Hereditary retinoschisis affected eight members of three generations of a family. The mode of transmission and the clinical features were not compatible with findings noted in either X-chromosome-linked or autosomal recessive forms of retinoschisis. The genetic and clinical features in this family strongly supported autosomal dominant inheritance, adding to the known genetic heterogeneity for the hereditary forms of retinoschisis. The expression of the condition varied in severity, but all affected members of the family had peripheral retinoschisis and peripheral retinal degeneration. Three had maculoschisis and five had macular pigmentary changes. Electroretinographic findings were normal in six of the eight.

Visual fields in metastatic choroidal carcinoma.

A large choroidal metastasis was diagnosed in the right eye of a 44-year-old man referred for admission to hospital because of 'retinal detachment.' At the same time in the second, symptomless, eye a very small metastasis was observed. Close follow-up during the next month showed an extremely rapid deterioration of visual acuity and visual field in this eye. This is thought to be characteristic of such metastatic tumours in contrast to the slower progress of choroidal malignant melanoma. The application of local radiotherapy to the same eye led to an impressive improvement in the visual acuity and visual field. The source of these bilateral choroidal metastases, which was found only after the patient's death, proved to a bronchial carcinoma.

Corneal endothelial changes under induced intraocular pressure elevation: a scanning and transmission electron microscopic study in rabbits.

Intraocular pressure was artificially raised to 60--70 mmHg in 7 albino rabbits for periods of 15 minutes to 4 hours. The corneal endothelium of these eyes was studied by transmission and scanning electron microscopy. A correlation between exposure time to elevated IOP, clinical signs observed by slit-lamp examination, and extent of morphological damage is clearly shown. In eyes exposed to high pressure for 15 and 30 minutes corneas remained transparent and only minimal changes could be detected by SEM, which consisted of small areas of cell with unevenness of their surface, occasional cellular ruptures, and diminution of cilia and microvilli. After 1--2 hours of exposure small, solitary corneal opacifications appeared. In these eyes more severe morphological changes affecting larger areas were observed, with additional cellular blebbing, excariocytosis, cellular rupture, disintegration, and disappearance seen in SEM. Thin sections revealed swelling of mitochondria, disorganisation of endoplasmic reticulum, and the existence of myelin bodies. In eyes exposed for 3 and 4 hours to high IOP corneal haziness, implying stromal oedema, appeared. In these eyes the areas affected were larger, the extent of damage being more severe. Many areas were bare of endothelium, surrounded by scattered cellular debris, and showed cells with ballooning surfaces and multiple ruptures. Even in severe cellular damage cellular junctions appeared intact. It is assumed that endothelial cells are more sensitive to IOP elevation than the cellular junctions and that injury to the active pump system due to morphological damage is responsible for the resultant corneal oedema.

Buckling procedures for retinal detachment caused by retrolental fibroplasia in premature babies.

Three premature babies with advanced stages of retrolental fibroplasia underwent retinal surgery by buckling procedures, with satisfactory results. The indications and surgical technical problems are discussed.