Vitreous Changes Research Articles

Infrared scanning laser tomography of macular cysts

ObjectiveTo perform three-dimensional, noninvasive, quantitative analysis of cystoid macular edema and macular cysts using infrared scanning laser tomography and to correlate findings with visual acuity (VA) as a basis for interventional studies. DesignCross-sectional, nonrandomized study. ParticipantsSeventeen patients (29–86 years of age) with macular cysts associated with a broad spectrum of diseases. InterventionConfocal infrared imaging with scanning laser tomography with the TopSS (790 nm) (Laser Diagnostic Technologies, San Diego, CA) with digitized images was used to perform three-dimensional, quantitative analysis of cysts in the central 5° of the macula. Main outcome measuresMeasurements of macular cyst number, area, volume, depth, slope, height of the surrounding macular elevation, and correlation with VA. ResultsScanning laser tomography detected macular cysts in all patients. The number per patient ranged from 1 through 15. Cysts were accompanied by surrounding macular elevation in 16 patients (mean macular height, 216 μm). The area covered by cysts in the central 5° was 0.087 to 0.969 mm2, and volume was 0.007 to 0.549 mm3. Visual acuity was significantly poorer in patients with greater cyst area (P = 0.0007), cyst volume (P = 0.0009), macular thickening (P = 0.0002), and cyst depth (P = 0.0013). Cyst number, average slope, and maximum slope, however, did not correlate significantly with VA. Grouping of macular cysts according to macular height and average cyst depth revealed that cysts in a more thickened retina were significantly deeper, had steeper slopes, and corresponded to worse VA. Macular height and average cyst depth were highly associated with each other, suggesting that in eyes with surrounding macular edema, cysts were deeper and may reflect more widespread tissue destruction. Individual confocal tomographic images provided additional information. Neither ophthalmoscopy nor fluorescein angiography delineated features such as retinal folds that suggested vitreous traction or changes in deeper layers that suggested occult choroidal new vessels. ConclusionsInfrared scanning laser tomography is a rapid and noninvasive imaging method that provides quantitative analysis of macular cysts in addition to qualitative information not seen clinically. Because poor VA is related to severe involvement of the central retina, scanning laser tomography could provide an objective outcome measure for interventional studies.

Vitreous Changes After Treatment of Retinopathy of Prematurity

Purpose: To investigate the vitreous findings in patients with cicatricial retinopathy of prematurity (ROP) who underwent retinal cryopexy and/or photocoagulation during the acute phase of the disease. Methods: Vitreous findings were evaluated in 15 patients (29 eyes) with cicatricial ROP by slit-lamp biomicroscopy and indirect ophthalmoscopy. Results: The ocular examination revealed that all eyes had extensive vitreous liquefaction that affected a large segment of the vitreous. A great deal of fibrillar condensation of the vitreous was present in membrane-like vitreous fibers that traversed the vitreous cavity to the periphery of the degenerating retina. These vitreous changes were most marked in the areas in which retinal cryopexy and/or photocoagulation had been performed. Despite advanced liquefaction, the posterior cortical vitreous was not separated from the retina in any eyes. Conclusion: In eyes with ROP that underwent retinal cryopexy and/or photocoagulation during the acute phase of the disease, the vitreous was abnormal, which may contribute to vitreoretinal traction that eventually leads to retinal breaks and detachment.

Optical phase change on reflection at v-SiO 2/Sn interface

An interferometric method was used for determination of the phase change on reflection at v-SiO 2/Sn interface in the infrared wavelength range in terms of IR spectroscopy. By evaluating the maximum (or minimum) positions of the interference fringes produced by multiple internal reflections at air/v-SiO 2/air and air/v-SiO 2/Sn interfaces, the wavelength-dependent refractive index of vitreous silica and phase change on reflection at v-SiO 2/Sn interface were determined. The evaluated refractive index of vitreous silica can be described with a three-term Sellmeier equation. The phase change on reflection was found to decrease with increasing wavelength of the incident light.

Combined system of biomicroscopic vitreous videography and photography.

To combine the techniques of biomicroscopic vitreous videography and vitreous photography when examining patients with age- or disease-related vitreous changes. We performed biomicroscopic vitreous videography and photography using the newly developed digital photo camera (one-half-inch three-charged coupled device camera with high resolution of 800 x 800 television lines) connected to a slit-lamp biomicroscope and compared it with conventional 35-mm slit-lamp photography in 24 consecutive eyes of 19 patients with idiopathic macular breaks. Stage 1 macular breaks were found in three eyes, stage 2 in four eyes, stage 3 in 11 eyes, and stage 4 in six eyes. Both vitreous videographs and still photographs were recorded and reviewed rapidly in one system. Using this system, dynamic vitreous changes and still vitreous images were documented clearly with real-time television monitoring without using flash illumination. The still images obtained from this system were better than those obtained using conventional 35-mm slit-lamp photography in cases with stage 1, 2, and 3 macular breaks (P = 0.0000000001 by Fisher's exact test). This combined system of biomicroscopic vitreous videography and photography may become the standard system of biomicroscopic vitreous examination.

Simple Method for Improving the Precision of Electrolyte Measurements in Vitreous Humor

Vitreous humor is widely used for postmortem biochemical analysis because it is easier to collect than cerebrospinal fluid and its composition changes more slowly after death than the composition of blood [reviewed by Coe (1)(2)]. The concentrations of sodium, urea, and creatinine in the vitreous humor change little over time, which means that it is possible to use these specimens to make postmortem diagnoses of renal failure, severe dehydration, salt intoxication, or excessive water intake (2)(3)(4)(5). Many drugs, including ethanol, can also be measured conveniently after death in vitreous humor (2). Unfortunately, the biochemical analysis of vitreous humor is not always straightforward, and several authors have reported problems with the reproducibility and accuracy of these measurements. These problems include unexplained differences in results obtained from left and right eyes (6)(7) and different results when specimens have been analyzed using different instruments (8). We encountered a problem with the reproducibility of vitreous humor electrolyte measurements made with two Hitachi random access analyzers and found that this …

Echographic Study of the Vitreoretinal Interface in Giant Retinal Tears

Vitreous and vitreoretinal interface changes were evaluated in giant retinal tears in order to plan surgical approach. Vitreal sineresis was evident in patients affected by primary giant retinal tears; in patients affected by retinal disinsertion the vitreous was adherent to the edge of the posterior flap, and in giant retinal tears secondary to IOL implantation, posterior vitreous detachment but no sineresis was displayed.

Vitreous humor analysis for selected biochemical parameters from cervids in Idaho.

Vitreous humor and liver samples were collected from hunter-harvested elk (Cervus elaphus) and mule deer (Odocoileus hemionus) in Idaho (USA). Concentrations of calcium, chloride, potassium, sodium, urea nitrogen and selenium were determined and evaluated according to species, age, gender, geographic location, and time elapsed following death. Vitreous humor analysis yielded reliable biochemical information for < or = 96 hr subsequent to the death of the animal. Vitreous potassium concentration changes over time could be used to estimate the time that elapsed following death.

Rhegmatogene Netzhautablösungen

Seasonal variations in the relative incidence of rhegmatogenous retinal detachment were reported as a trend in several studies on the database of relatively limited cohort sizes. An analysis on this topic was performed with a long-term database. A total of 3073 files of patients with rhegmatogenous retinal detachment, covering 11 years of observation, were reviewed for this study. Patients with signs of long-standing detachment or other predisposing diseases were excluded, so that a basic study population of 2314 patients remained for the analysis. The averaged seasonal incidence of rhegmatogenous detachments revealed a significant (P < 0.005) mid-summer peak (n in July = 228) and a winter trough (mean of December-January = 161; difference = 36%). Phase and curve fitting of the seasonal variations in the number of retina detachment cases was similar to the seasonal variation of the astronomic duration of the day (P < 0.001). The relation was closer compared to the average duration of light exposure per day calculated from behavioural data and the astronomic length of light phase (P < 0.0002). This long-time study revealed a close correlation of the relative seasonal incidence of retinal detachment and the seasonal variation of light hours per day. So far, this observations cannot be explained pathogenetically. Two basic hypotheses ought to be investigated further: (1) The influence of light on the generation of toxic oxygen radicals and the subsequent destruction of the vitreous and (2) possible light-induced changes in vitreoretinal adhesion.

Vitreous fluorophotometry and changes in blood‐retinal barrier permeability induced by Bendazac lysine

Vitreous fluorophotometry was used to investigate the effect of Bendazac lysine on the blood retinal barrier in 12 insulin-dependent diabetics with mild background retinopathy. The study was a randomized, double blind, cross-over trial, drug versus Placebo. Each treatment period was of 4 months. The vitreous penetration coefficient was reduced by 21% (95% c.i. 12, 30; p = 0.001) by treatment with respect to Placebo.

Electroretinographic findings in Fuchs' heterochromic cyclitis.

Fuchs' heterochromic cyclitis (FHC) is an inflammatory disease of unknown aetiology. Although anterior segment signs and vitreous changes are well recognised, retinal features are unusual. To assess the extent of retinal involvement, we performed electrophysiological testing in a group of FHC patients. Retinal function was assessed by means of flash electroretinogram (ERG) using a Ganzfeld stimulus, and pattern electroretinogram (PERG) using a checkerboard stimulus of spatial frequency 0.5 and 1.0 cycle per degree reversing at 6 Hz. A total of 21 patients with unilateral, normotensive FHC with visual acuities of 6/5 to 6/9 were studied. In the flash ERG, selective scotopic b-wave abnormalities occurred in 9 (43%) of 21 FHC eyes. Despite clear media and no history of ocular surgery, 7 patients showed abnormalities of the PERG. These electrophysiological findings suggest subclinical damage to the inner retinal layers, but not involving the photoreceptors, in eyes with FHC.

Inward and outward permeability of the blood-retinal barrier in experimental myopia.

To investigate the pathophysiology of the retina in myopia, vitreous fluorophotometry was used to evaluate the permeability of the blood-retinal barrier (BRB) in experimentally induced myopia in cynomolgus monkeys. Five animals underwent unilateral eyelid suturing. The suture was removed temporarily at 3, 10, 16, 28 and 36 months, and the dioptric power and axial length were measured in both eyes. Vitreous fluorophotometry was performed before and 60 min after intravenous injection of fluorescein-Na. BRB inward permeability (P(in)) was determined by a computer simulation method. At 36 months, fluorescein-Na was injected into the vitreous cavity, and the intraocular fluorescence was measured. BRB outward permeability (P(out)) was determined by the computer simulation method. Significant myopia developed by 10 months after suturing and progressed thereafter. Starting at 10 months, the P(in) of sutured eyes increased significantly compared with control fellow eyes, and the increase continued throughout the observation period. At 36 months, the BRB P(out) was significantly lower (P < 0.05) in the myopic than in the emmetropic fellow eyes, suggesting decreased active transport mechanisms at the BRB in myopia. Our study demonstrated, for the first time, abnormal permeability of the BRB in myopic monkey eyes. Such abnormal permeability may play an important role in the development in human myopes of retinal and vitreous changes such as retinal detachment. Thus, simply correcting refractive errors surgically may not represent a cure for myopia. Patients who have had refractive surgery to correct myopia should also be closely followed up by vitreo-retinal specialists to manage vitreo-retinal disorders in originally myopic eyes.

Vitreous changes and retinal detachment in highly myopic eyes.

This report on 496 highly myopic eyes that underwent transcleral or vitreoretinal surgery for retinal detachment (RD) focuses particularly on how changes in the vitreous gel and the resulting modifications of the vitreoretinal interface produce typical characteristics and complications. According to the pattern of vitreous modifications the 496 eyes were divided into five groups: 1) eyes with uniform PVD (108 eyes) 2) eyes with PVD spreading towards the upper quadrants (231 eyes) 3) eyes with extensive vitreous liquefaction (EVL) and condensations of the vitreous base (51 eyes) 4) eyes with posterior vitreous lacuna (PVL, 87 eyes) 5) eyes with very limited PVD (19 eyes). Age, degree of myopia, surgical procedures and final results are reported for each group. A strong correlation was observed between vitreous changes and clinical picture of RD especially in the group of PVL and EVL. In the PVL group a higher degree of myopia was found and more pronounced posterior staphyloma. Frequently the posterior hyaloid, in the form of a thin, extremely smooth membrane, was hard to separate from the inner posterior retina during surgery. Posterior retinal breaks, including macular holes, were found in 56% of eyes. The presence of EVL with condensation of the vitreous base was correlated with giant retinal tear (GRT) in 70% of cases (36 of 51 eyes). Sixteen GRT were also found in the group of uniform PVD, but these were less extensive and located more posteriorly than in the EVL group. In the former group there were better surgical results because of a lower incidence of PVR. In 46% of the eyes of our series (group 2), PVD extended mostly in the upper quadrants with no vitreous detachment inferiorly. In these cases there was a clinical appearance of inferior vitreous collapse. These eyes had 92% of peripheral superior retinal breaks. Relapses of RD in this group almost invariably occurred in the inferior quadrants.

Evidence of cross-link formation of vitreous collagen during experimental ocular inflammation.

To determine the mechanisms of vitreous changes during ocular inflammation. We investigated vitreous changes, with special emphasis on collagen, in an experimental model of ocular inflammation induced by intravitreal injection of endotoxin (Escherichia coli) in rabbits. Inflammation caused gel contraction and loss of elasticity, accompanied by release of a water-like liquid from the gel, and increases in the amount of insoluble material and high-molecular-weight components of vitreous collagen, presumably due to extensive cross-links of the collagen molecules. Those changes were partially inhibited by intravitreal injection of superoxide dismutase. The cross-links of vitreous collagen may promote vitreous gel contraction and release of a water-like liquid from the gel. Superoxide anion may play a role in this process.

A CLINICAL STUDY OF THE DEVELOPMENT OF POSTERIOR VITREOUS DETACHMENT IN HIGH MYOPIA

The correlation of age, axial length, and myopic chorioretinal atrophy with vitreous changes in high myopia were analyzed to investigate the development of posterior vitreous detachment (PVD) in high myopia. The vitreous condition of 329 consecutive eyes with high myopia (more than -8.25 diopters (D) and more than 26.0 mm of axial length) was examined biomicroscopically with a +90-D preset lens and a Goldmann three-mirror contact lens. The prevalence of PVD in high myopia was 12.5% in patients between 20 and 29 years of age, and it increased with age. The incidence of PVD in eyes with axial length of more than 30.0 mm was 60.7% and was statistically higher than the prevalence in eyes with an axial length of less than 29.9 mm (P < 0.01). Multiple logistic regression analysis showed that age and axial length were statistically significant factors in the development of PVD and lacuna formation in high myopia (P < 0.01), but the influence of chorioretinal atrophy was not significant. The results of this study suggest that liquefaction of the vitreous begins at a relatively young age in patients with high myopia and progresses with age and axial elongation, thus resulting in a frequent occurrence of PVD.

Erosive Vitreoretinopathy: A New Clinical Entity

Vitreoretinopathies are disorders characterized by an abnormal vitreous gel structure and associated retinal changes. The authors report a pedigree with vitreous changes characteristic of the vitreoretinopathies, but with retinal pigment epithelial changes, electroretinographic abnormalities, and a clinical course distinct from previously described entities. Twenty-six family members were examined. Complete ophthalmologic examinations, electroretinography, and perimetry were performed on patients who were at genetic risk for the disease. Particular attention was given to vitreous morphology and examination of the retinal and retinal pigment epithelium (RPE). Fifteen individuals affected with an autosomal dominant vitreoretinal degeneration were identified. The disease is characterized by nyctalopia, progressive visual field loss, marked vitreous syneresis, progressive RPE atrophy, and combined traction-rhegmatogenous retinal detachments (11 patients). Thinning or "erosion" of the RPE in younger patients permits increased visualization of the choroidal vessels. In advanced conditions, equatorial areas are seen that appear clinically devoid of RPE, with extensive posterior atrophy in older patients. Diffuse rod-cone dysfunction is demonstrated by electroretinography. High myopia, epiphyseal dysplasia, orofacial anomalies, and systemic manifestations characteristic of other vitreoretinopathies are not present. The authors describe an entity clinically distinct from other vitreoretinopathies. The disease is characterized by pronounced vitreous abnormalities, complicated retinal detachments, and a progressive pigmentary retinopathy. The most unusual and constant feature is the progressive change in RPE with concurrent visual field constriction and electroretinographic abnormalities. Because the RPE initially seems normal and progressively thins or "erodes" in the equatorial periphery, the descriptive name "erosive" vitreoretinopathy is proposed.

Age-related changes in the molecular properties of vitreous collagen.

To understand the molecular events underlying rheological vitreous changes, age-related changes in the molecular properties of bovine and human vitreous collagen were monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The adult bovine vitreous showed an increase in the high molecular-weight components of the collagen compared with the young samples. In addition, the apparent molecular size of the alpha-chain of the adult type II collagen was slightly larger than that of the young samples. The same tendency also was observed in human vitreous. The increase of high-molecular-weight components of the vitreous collagen could be attributed to intermolecular cross-links of the peptide chains.

Vitreous body fluorescence changes after retinal laser coagulation in a rabbit in vivo model

Vitreous body fluorescence changes after retinal laser coagulation in a rabbit in vivo model

Comparative study of vitreoretinal relationships using biomicroscopy and ultrasound

We prospectively studied 29 consecutive eyes with proliferative diabetic retinopathy that showed media clear enough to enable characterization of vitreoretinal relationships by biomicroscopy. Vitreoretinal relationships were also determined by contact B-scan ultrasound. With both techniques, these relationships were documented by photographs and drawings. Biomicroscopy showed complete posterior vitreous detachment (PVD) in 4 eyes (14%), partial PVD in 18 (62%), and no PVD in 7 (24%). Ultrasound examination revealed complete PVD in 4 eyes (14%), partial PVD in 19 (66%), and no PVD in 6 (21%). The results we obtained using ultrasound agreed significantly with those obtained by biomicroscopy [Cohen's kappa = 0.93, 95% confidence interval = (0.80, 1.06)]. Ultrasound detected vitreous changes more easily than biomicroscopy when mild media opacities were present and when the equatorial areas of the globe were examined. Results suggest that ultrasound is adequate to determine vitreoretinal relationships in eyes with clear media and that it is a good alternative to biomicroscopy in eyes with significant media opacities.

Vitreous Changes and Macular Edema in Central Retinal Vein Occlusion

The condition of the posterior vitreous was determined in 56 eyes with central retinal vein occlusion (CRVO). Using a life-table analysis, it was studied in 56 eyes. The incidence of posterior vitreous detachment (PVD) in the CRVO eyes at the first vitreous examination did not differ significantly from that in 64 age-matched control eyes. However, the incidence of PVD in CRVO eyes increased from 39.3% at the first vitreous examination to 58.5% after 6 months, and to 69.6% 1 year from the examination. The incidence of PVD in CRVO eyes during follow-up was statistically higher than that of the controls (P = .009). The incidence of PVD after the first vitreous examination was significantly higher in eyes with hemorrhagic retinopathy than in eyes with venous stasis retinopathy (P = .04). In the 34 eyes with macular edema, the edema lasted significantly longer in those with vitreomacular attachment (VMA) at the first examination than in those without VMA at this time (P = .02). VMA may play an important role in the pathogenesis and chronicity of macular edema in CRVO.

Alterations in rabbit vitreal fine structure following C3F8 injection

This study examines the morphological and histochemical changes in the cortical vitreous of 36 rabbit eyes following C3F8 intravitreal gas injection. Eyes were examined by light microscopy (LM) using a modified cryofixation and cryosectioning technique that prevented the loss of soluble tissue moieties and permitted collagen and proteoglycan histochemistry as well as enzyme digestion with hyaluronidase. LM and scanning electron microscopy (SEM) of cryosectioned normal eyes revealed an elaborate fibrillar matrix extending 100-190 microns from the basal lamina of the retina into the vitreous proper, which seemed to be composed of collagen fibrils intimately associated or wrapped in proteoglycan. Following the full expansion of the C3F8 gas bubble in the vitreous, the cortical fibrillar meshwork was absent from the retinal surface and a dense, collagenous material accumulated in the anterior vitreous, especially between the ciliary processes and over the posterior face of the lens. At 41 days postinjection, the fibrillar matrix was reforming and the vitreal cavity was filled with fluid and numerous fibrillar-mucinous islands. These islands did not form sheets or membranes, nor did they attach to either the posterior or the anterior retinal surface. The cortical fibrillar meshwork had reformed at 61 days' recovery; however, the condensed fibrillar material against the lens and filling the spaces between the ciliary processes had not resorbed. Neither shearing of the cortical gel or fibrillar matrix nor congestion of the anterior vitreous was observed in eyes only partially filled with gas.