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PubMedDate not supplied

Retinal detachment and retinal holes in retinitis pigmentosa sine pigmento.

Retinal detachment and retinal holes in two family members with retinitis pigmentosa sine pigmento are reported. We believe these are the first such cases reported in the literature. We describe the presenting symptoms and management, including cryotherapy, scleral buckling procedure, and sulfur hexafluoride injection (SF6), resulting in stable visual acuity in one case and retinal reattachment and improved visual acuity in the other case.

Adult↗
PubMed1997

Biotransformation of all-trans-retinal, 13-cis-retinal, and 9-cis-retinal catalyzed by conceptal cytosol and microsomes.

Oxidative conversions of all-trans-retinal (t-RAL), 13-cis-retinal (13-cRAL), and 9-cis-retinal (9-cRAL) to their corresponding retinoic acids (RAs) catalyzed by rat conceptal cytosol (RCC) or microsomes (RCM) were studied. The primary product of RCC-catalyzed oxidations of both t-RAL and 13-cRAL was t-RA, with only trace amounts of 13-cRA and 9-cRA. In the RCC-catalyzed oxidation of 9-cRAL, generated t-RA, 9-cRA, and 13-cRA constituted approximately 56, 34, and 10%, respectively, of the total RAs. For all RCC-catalyzed retinal oxidations, NAD was a much more effective cofactor than NADP. And t-RAL and 13-cRAL were much better substrates than 9-cRAL. Formaldehyde, acetaldehyde, citral, and disulfiram were investigated as inhibitors, but only citral and disulfiram effectively inhibited the RCC-catalyzed conversion of t-RAL or 13-cRAL to t-RA. Methanol and ethanol failed to inhibit either reaction even at very high concentrations (> or = 10 mM). RCM exhibited lower specific enzymatic activities than RCC in catalyzing oxidations of t-RAL, 13-cRAL, and 9-cRAL, indicating that the cytosolic fraction was dominant for converting retinals to RAs. The predominant RA produced from RCM-catalyzed oxidations of t-RAL, 13-cRAL, or 9-cRAL was t-RA for each substrate, and again NAD was a much more effective cofactor than NADP in all cases. For RCM-catalyzed oxidations of RALs, 13-cRAL was a much better substrate than t-RAL or 9-cRAL. Methanol and ethanol were not effective inhibitors for RCM-catalyzed oxidations of t-RAL or 13-cRAL. In RCM-catalyzed reactions, citral (10 mM) completely inhibited oxidation of t-RAL but showed only a minor effect on oxidation of 13-cRAL. 13-cRA was converted almost completely to t-RA after 2 hr of incubation with RCC.

Animals↗
PubMed1993

Electron microscopic immunocytochemical demonstration of blood-retinal barrier breakdown in human diabetics and its association with aldose reductase in retinal vascular endothelium and retinal pigment epithelium.

Light-microscopic immunohistochemical staining for albumin has been used to localize sites of blood-retinal barrier (BRB) breakdown in ocular disorders, but the mechanism for BRB compromise cannot be resolved at this level. Using eyes up to 2 days post-mortem from normal patients or from patients with diabetic retinopathy, or other disorders known to cause BRB failure, electron-microscopic immunocytochemistry reveals focal breakdown of the inner BRB, comprised of the retinal vascular endothelium (RVE), which appears to be mediated by diffuse permeation of the RVE cells and by vesicular transport. Permeation of the retinal pigmented epithelial (RPE) cells that comprise the outer BRB also occurs, but there is no evidence of opening of tight junctions between RVE or RPE in any of the disorders evaluated. Increased aldose reductase (AR) expression in the RVE and RPE cells of diabetics as well as in the perivascular retinal astrocytes, which interact with RVE cells to establish the inner BRB, suggests that AR activity and the subsequent intracellular accumulation of sorbitol in these cell types may impair the function of the BRB in diabetes.

Aged↗
PubMed1997

The effects of retinal ischemia on retinal nerve fiber layers of patients with retinal vein occlusion.

PURPOSE: To demonstrate the effects of retinal ischemia on retinal nerve fiber layer (RNFL) and the associated visual dysfunctions. METHODS: 52 subjects with retinal vein occlusion (RVO) were studied both in RVO eyes and in the contra-lateral eyes via red-free light fundus photography. The semi-quantitative analysis of RNFL defects was done, and the severity of RNFL defects of the ischemic and the non-ischemic groups were compared. RESULTS: The RNFL defects occurred in 75.5% of the total 53 eyes with RVO. The incidences of RNFL defects were significantly higher in eyes with cotton-wool spots and capillary non-perfusion than in other RVO eyes and controls. The RNFL defects were significantly severer in ischemic eyes than in non-ischemic ones. CONCLUSION: Retinal ischemia can result in RNFL defects, and the severity of RNFL defects was closely related to that of ischemia.

Adult↗
PubMed1989

[Role of the vitreous in retinal neovascularization evaluated by a comparison of central retinal vein occlusion and branch retinal vein occlusion].

Thirty three patients (33 eyes) with central retinal vein occlusion (CRVO) and 80 patients (81 eyes) with branch retinal vein occlusion (BRVO) were studied in an attempt to investigate the role of the vitreous in the formation of retinal neovascularization. All these eyes had some areas of capillary nonperfusion confirmed by fluorescein angiography and no scatter photocoagulation before the first examination. The incidence of new vessels at the optic disc (NVD) in CRVO was not significantly different from that in BRVO. However, the incidence of new vessels elsewhere (NVE) in CRVO was significantly less than that in BRVO. Follow-up vitreous examination of 36 cases while they had not developed NVD and/or NVE showed a higher incidence of posterior vitreous detachment from the mid-peripheral retina (MP-PVD) in CRVO than in BRVO. On the other hand, there was no statistically significant difference in the incidence of posterior vitreous detachment from the optic disk (D-PVD) between CRVO and BRVO. The high incidence of MP-PVD in CRVO may explain the low incidence of NVE in CRVO.

Adult↗
PubMed2000

Dominant late-onset retinal degeneration with regional variation of sub-retinal pigment epithelium deposits, retinal function, and photoreceptor degeneration.

PURPOSE: To clarify the pathogenesis of late-onset retinal degeneration (L-ORD), an autosomal dominant disorder characterized by thick deposits of lipid-rich material between the retinal pigment epithelium (RPE) and Bruch's membrane. STUDY DESIGN: Comparative clinicopathologic case report and case series. TISSUES: Eyes of an 82-year-old L-ORD eye donor and an age-matched control. SUBJECTS: Five descendants of the eye donor and his affected sister. METHODS: The eyes were processed for histopathologic examination, including electron microscopy and immunohistochemistry. Family members were examined clinically and with retinal function tests. RESULTS: The L-ORD eye had sub-RPE deposits that were positive for lipid, including esterified and unesterified cholesterol. The deposits were thinnest in the macula, which retained the highest percentage of photoreceptors. In the periphery, RPE thinning and photoreceptor loss correlated with thickness of the sub-RPE deposits. The eye donor was asymptomatic until his late 50s, when he developed problems with adapting to darkness. At age 68, the eye donor had normal acuity but a midperipheral scotoma and subnormal electroretinograms (ERGs); visual loss was progressive. The five descendants (at the time of examination ages 44-58) of the eye donor and his affected sister, who were at 50/50 risk of inheriting L-ORD, had normal ERGs, but four showed defects in dark adaptation. The dark adaptation abnormalities had a distribution similar to the thickness of the sub-RPE deposits in the eye donor, with slow kinetics in the midperiphery and normal kinetics centrally. CONCLUSIONS: The L-ORD donor eye differed from a previous case in the regional distribution of sub-RPE deposits and photoreceptors. In the next generation of this L-ORD family, the first expression of disease, abnormal dark adaptation, mirrored the regional distribution of the deposits in the donor eye. The fine structure and staining characteristics of the sub-RPE deposits in L-ORD resemble those in age-related macular degeneration and Sorsby fundus dystrophy.

Adult↗
PubMed2007

Retinal stem cells transplanted into models of late stages of retinitis pigmentosa preferentially adopt a glial or a retinal ganglion cell fate.

PURPOSE: To characterize the potential of newborn retinal stem cells (RSCs) isolated from the radial glia population to integrate the retina, this study was conducted to investigate the fate of in vitro expanded RSCs transplanted into retinas devoid of photoreceptors (adult rd1 and old VPP mice and rhodopsin-mutated transgenic mice) or partially degenerated retina (adult VPP mice) retinas. METHODS: Populations of RSCs and progenitor cells were isolated either from DBA2J newborn mice and labeled with the red lipophilic fluorescent dye (PKH26) or from GFP (green fluorescent protein) transgenic mice. After expansion in EGF+FGF2 (epidermal growth factor+fibroblast growth factor), cells were transplanted intravitreally or subretinally into the eyes of adult wild-type, transgenic mice undergoing slow (VPP strain) or rapid (rd1 strain) retinal degeneration. RESULTS: Only limited migration and differentiation of the cells were observed in normal mice injected subretinally or in VPP and rd1 mice injected intravitreally. After subretinal injection in old VPP mice, transplanted cells massively migrated into the ganglion cell layer and, at 1 and 4 weeks after injection, harbored neuronal and glial markers expressed locally, such as beta-tubulin-III, NeuN, Brn3b, or glial fibrillary acidic protein (GFAP), with a marked preference for the glial phenotype. In adult VPP retinas, the grafted cells behaved similarly. Few grafted cells stayed in the degenerating outer nuclear layer (ONL). These cells were, in rare cases, positive for rhodopsin or recoverin, markers specific for photoreceptors and some bipolar cells. CONCLUSIONS: These results show that the grafted cells preferentially integrate into the GCL and IPL and express ganglion cell or glial markers, thus exhibiting migratory and differentiation preferences when injected subretinally. It also appears that the retina, whether partially degenerated or already degenerated, does not provide signals to induce massive differentiation of RSCs into photoreceptors. This observation suggests that a predifferentiation of RSCs into photoreceptors before transplantation may be necessary to obtain graft integration in the ONL.

Animals↗
PubMed1977

Observations on the retinal pigment epithelium and retinal macrophages in experimental retinal detachment.

After experimental retinal detachment in rabbits macrophages are a prominent feature in the subretinal space or within the retina. Two sources for these macrophages are identified. The retinal pigment epithelium (RPE) may undergo metaplasia and actively 'bud'; the evolving macrophage is then formed by a vitreal protrusion of the cytoplasm of an RPE cell which is 'nipped off' by lateral protrusions from adjacent cells. In addition, in regions of RPE proliferation, blood-borne cells were found in Bruch's membrane and among the mass of proliferated RPE cells, suggesting that blood-borne cells may pass from the choroidal circulation through Bruch's membrane and the RPE layer.

Animals↗
PubMed1999

Retinal pigment epithelial dysfunction in human immunodeficiency virus-infected patients with cytomegalovirus retinitis.

OBJECTIVE: Prior clinical observations led the authors to examine electrophysiologic measures of retinal (electroretinogram [ERG]) and retinal pigment epithelial (electro-oculogram [EOG]) function in patients infected with human immunodeficiency virus (HIV) who either had or did not have cytomegalovirus (CMV) retinitis in order to determine if the ERG or EOG measures were differentially affected in CMV retinitis. DESIGN: Cross-sectional study. PARTICIPANTS: Forty-one HIV-infected patients (20 with and 21 without CMV retinopathy) were evaluated. INTERVENTION: ERGs and EOGs were recorded. Patients' fundi were evaluated by indirect ophthalmoscopy or fundus photography. MAIN OUTCOME MEASURES: The ERG a- and b-wave amplitudes and EOG light/dark amplitude ratio (L/D ratio) from the eyes of all patients were compared with values 2 standard deviations from the mean of a normal sample. The area of the retinal lesions was estimated from fundus photographs or from careful drawings made during indirect ophthalmoscopy. RESULTS: The majority of the eyes (64.5%) of the patients with CMV retinitis had subnormal L/D ratios, and most eyes (95%) of patients without CMV retinitis had normal L/D ratios. Only six eyes (four with and two without CMV retinopathy) had subnormal a-wave amplitudes, and there was no significant correlation between a-wave amplitude and the L/D ratio for patients with CMV retinitis. Most eyes (80.6%) of the patients with CMV retinitis had subnormal b-wave amplitudes, but there was no significant correlation between b-wave amplitude and L/D ratio in the patients with CMV retinitis. In three patients with CMV retinitis selected to exemplify the range of effects on the ERG and EOG, the b-wave amplitude loss was roughly proportional to the area of retina visibly affected in indirect ophthalmoscopy. One patient had a nonrhegmatogenous retinal detachment. CONCLUSIONS: Middle retinal function, as reflected in the b-wave amplitude, and retinal pigment epithelial function, as reflected in the L/D ratio, were both compromised in CMV retinitis, but the effect on function in the two layers of the retina appeared independent because there was no significant correlation between the L/D ratio and b-wave amplitude. The decrease in L/D ratio was not secondary to loss of photoreceptor function and probably represents a dysfunction of the retinal pigment epithelium because there was no significant correlation between a-wave amplitude, which was normal in most cases, and L/D ratio. The inner retinal pathology of CMV retinitis is visible clinically and was associated with decreases in b-wave amplitude in this and previous studies. The significant independent retinal pigment epithelial dysfunction demonstrated in this study may be an important predisposing factor to retinal detachment in CMV retinitis.

AIDS-Related Opportunistic Infections↗
PubMed2006

[Long-term results of argon laser retinal photocoagulation for retinal ruptures].

AIM: To present longterm results of laser photocoagulation for retinal ruptures in preventing retinal detachment. METHODS: Retrospective analysis of 405 patients (430 eyes) operated on (treated) with argon laser photocoagulation for retinal tear from January 1992 to January 2002. Inclusion criteria were retinal rupture(s) on one or both eyes. Follow up period was 2 to 9 years. Indications for laser treatment were symptomatic retinal ruptures, ruptures with vitreoretinal tractions, ruptures associated with high myopia, retinal pathology in the fellow eye, aphakia, pseudophakia, eye trauma, vitreous hemorrhage, and ruptures with shallow retinal detachment not exceeding 1-2 disc diameter. Laser treatment was done with Coherent 900, Novus and Ultima lasers, usually in one session under topical anesthesia. Laser surgery consisted of 2-3 continuous rows surrounding the lesion, power setting 100-300 mW, time 0.2 s, spots 100-200 micron in size. RESULTS: The types of tear were analyzed and tabularly presented. There were 20 (4.6%) round holes with no operculum, 32 (7.4%) round holes with operculum and 143 (33%) horseshoe tears with visible vitreoretinal tractions. Retinal ruptures were associated with vitreous hemorrhage in 96 (22.3%) eyes, myopic changes were found in 82 (19%) eyes, and pseudophakia in 56 (13%) eyes. Posterior vitreous detachment was found in 146 (34%) eyes and traumatic ruptures were found in 27 (6.3%) eyes. The position and number of retinal ruptures were analyzed. Single ruptures were found in 255 (59%) and multiple ruptures in 175 (45%) eyes. In the group of single ruptures, superotemporal localization was found in 120 (28%) eyes. The most common complication following laser treatment was retinal detachment in 24 (6%) eyes. Two (0.5%) eyes developed proliferative vitreoretinopathy. Twenty-four eyes with retinal detachment after laser treatment were operated on. Scleral buckling procedure was done in 20 (83%) and pars plana vitrectomy in 4 (17%) eyes. Two (8.5%) eyes underwent repeat vitrectomy due to postoperative complications. DISCUSSION: Today there is a strong suggestion that all symptomatic retinal ruptures should be treated. Ruptures with small and shallow retinal detachments should be treated. If there is vitreoretinal traction and retinal defect, these eyes should be treated. There are some medical eye conditions where it is wise to perform laser treatment for retinal rupture (aphakia, pseeudophakia, myopia, retinal changes in fellow eye, vitreous hemorrhage, trauma). In our study there was a number of asymptomatic retinal ruptures that were treated. The reason was a very long period of time elapsed from the treatment of our first patients (15 years before), when it was considered necessary to treat these patients. CONCLUSION: The most serious complication of retinal rupture, retinal detachment, can be prevented by early laser photocoagulation. There are some conditions associated with retinal rupture that require obligatory treatment. In our study, the success rate was 94%. No major complications attributable to laser treatment were noted.

Adolescent↗
PubMed2003

[Experiment study of infusing tPA in retinal vein for treatment of retinal vein occlusion].

OBJECTIVE: To Investigate the effectiveness and complications of injection of tissue plasminogen activator into a retinal vein for treatment of retinal vein occlusion via micropuncture of the retinal vein. METHODS: Thirty miniature pigs (one eye of each pig) were produced photodynamic thrombi of retinal vein by injecting Rose bengal (20 mg/kg) into the ear vein, and randomly divided into three groups: 1. control (n = 8), 2. infusion of sterile water (n = 8) or 3. infusion of tissue-type plasminogen activator (n = 14) in obstructed retinal vein. In the first group no micropuncture of retinal vein was performed. In the others micropuncture of retinal vein were performed by a micromanipulator that we designed and sterile water was infused in retinal vein in the second group or tissue-type plasminogen activator was infused in the third one. Fluorescent angiography and histological study were performed to document the morphological alterations with clinical observations. RESULTS: 18 eyes were successfully performed micropuncture of retinal vein in the 22 eyes (81.4%). Except stopping operation due to surgical accident, there were 7 eyes that the thrombi were lysed in 9 eyes by infusion of tissue-type plasminogen activator in obstructed retinal vein (77.8%). If the micropipette was not accurate for puncturing the vessels, the vessels' wall could be ruptured and hemorrhage appeared. If thrombi of retinal veins were lysed, no bleeding and no leakage of the infused drug were observed from the site of micropuncture after micropipette was withdrawn from the vessel. Sterile water failed to flush the clot downstream. When the thrombus failed to be dislodged, the infusion fluid would back flow into the distal retinal vein and, an exudative retinal detachment would occur. In the first group, the retina exhibited hemorrhages and edema due to the vein occluded. In the second group, sterile water resulted in exaggerated retinal edema and exudative retinal detachment. In the third group, after thrombi of retinal veins were lysed, the hemorrhages and edema of retinal tissues were reduced significantly in few days. CONCLUSIONS: Infusing thrombolytic agents into the thrombosed retinal vein is a new method for treatment of retinal vein occlusion. This surgery must performed accurately by a special design. This study demonstrated that the rate and dose of thrombolytic agents infused in retinal vein should be limited in case of injuring retina tissues.

Animals↗
PubMed1997

Retinal detachment after branch retinal vein occlusion: influence of the type of break on the outcome of vitreous surgery.

BACKGROUND: Branch retinal vein occlusion (BRVO) is occasionally complicated by two types of retinal breaks (retinal holes without vitreous traction or retinal traction tears) that may lead to a rhegmatogenous retinal detachment (RRD). The authors describe surgical results of vitrectomy for RRD after BRVO and investigate whether there is any difference between clinical features or surgical results from eyes with the two types of retinal breaks. PATIENTS AND METHODS: The authors retrospectively studied 25 patients (25 eyes) who underwent vitrectomy for RRD after BRVO. Twelve of 25 eyes (48%) had a detachment secondary to one or more retinal holes (group I), and 13 of the eyes (52%) had one or more retinal tears (group II). RESULTS: Seventeen of the eyes (68%) achieved total retinal reattachment after the initial surgery; 22 (88%) did so by the time of final examination. Patients with retinal holes achieved more favorable final vision than those with retinal tears (P = 0.0391). A higher rate of preoperative macular detachment (P = 0.0112) and a higher rate of recurrent retinal detachment after initial vitrectomy (P = 0.0302) were the factors associated with the reduced final visual acuity in patients with retinal tears. The increased rate of recurrent retinal detachment in patients with retinal tears was associated with a higher rate of existing preretinal neovascular membranes (P = 0.0112) and a trend toward an increased incidence of intraoperative iatrogenic retinal breaks. CONCLUSION: Among patients who undergo vitrectomy for RRD after BRVO, better surgical results are expected in eyes with retinal holes without vitreous traction than in those with retinal traction tears. This difference is thought to be due to the difference in vitreoretinal anatomy between eyes with the two types of retinal breaks.

Aged↗
PubMed2005

Interventions for asymptomatic retinal breaks and lattice degeneration for preventing retinal detachment.

BACKGROUND: Asymptomatic retinal breaks and lattice degeneration are visible lesions that are risk factors for later retinal detachment. Retinal detachments occur when fluid in the vitreous cavity passes through tears or holes in the retina and separates the retina from the underlying retinal pigment epithelium. Creation of an adhesion surrounding retinal breaks and lattice degeneration, with laser photocoagulation or cryotherapy, has been recommended as an effective means of preventing retinal detachment. This therapy is of value in the management of retinal tears associated with the symptoms of flashes and floaters and persistent vitreous traction upon the retina in the region of the retinal break, because such symptomatic retinal tears are associated with a high rate of progression to retinal detachment. Retinal tears and holes unassociated with acute symptoms and lattice degeneration are significantly less likely to be the sites of retinal breaks that are responsible for later retinal detachment. Nevertheless, treatment of these problems is frequently recommended, in spite of the fact that the effectiveness of this therapy is unproven. OBJECTIVES: The purpose of this review is to evaluate the effectiveness of interventions for asymptomatic retinal breaks and lattice degeneration. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which includes the Cochrane Eyes and Vision Group Trials Register) on The Cochrane Library (Issue 3 2004) MEDLINE (1966 to July 2004) and EMBASE (1980 to August 2004). Textbooks regarding retinal detachment and the reference lists of relevant reports were reviewed for additional study reports. Experts in the field were contacted for details of other published and unpublished studies. SELECTION CRITERIA: This review was designed to include randomised controlled trials in which one treatment for asymptomatic retinal breaks and lattice degeneration was compared to another treatment or to no treatment. DATA COLLECTION AND ANALYSIS: One reviewer assessed the search results and collected relevant studies. Since no studies met the inclusion criteria, no studies were assessed for methodological quality. No data were extracted and no meta-analysis could be performed. MAIN RESULTS: No trials were found that met the inclusion criteria for this review. AUTHORS' CONCLUSIONS: No conclusions could be reached about the effectiveness of surgical interventions to prevent retinal detachment in eyes with asymptomatic retinal breaks and/or lattice degeneration. Some current recommendations for treatment, based upon a consensus of expert opinion, are contradicted by the best available evidence.

Humans↗
PubMed2001

Interventions for asymptomatic retinal breaks and lattice degeneration for preventing retinal detachment.

BACKGROUND: Asymptomatic retinal breaks and lattice degeneration are visible lesions that are risk factors for later retinal detachment. Retinal detachments occur when fluid in the vitreous cavity passes through tears or holes in the retina and separates the retina from the underlying retinal pigment epithelium. Creation of an adhesion surrounding retinal breaks and lattice degeneration, with laser photocoagulation or cryotherapy, has been recommended as an effective means of preventing retinal detachment. This therapy is of value in the management of retinal tears associated with the symptoms of flashes and floaters and persistent vitreous traction upon the retina, because such symptomatic retinal breaks are associated with a high rate of progression to retinal detachment. Retinal tears and holes unassociated with acute symptoms and lattice degeneration are significantly less likely to be the sites of retinal breaks that are responsible for later retinal detachment. Nevertheless, treatment of these problems is frequently recommended, in spite of the fact that the effectiveness of this therapy is unproven. OBJECTIVES: The purpose of this review is to evaluate the effects of interventions for asymptomatic retinal breaks and lattice degeneration. SEARCH STRATEGY: We searched the Cochrane Controlled Trials Register - CENTRAL (which includes the Cochrane Eyes and Vision Group specialized register), MEDLINE and EMBASE. Textbooks regarding retinal detachment and the reference lists of relevant reports were reviewed in an effort to find additional study reports. Experts in the field were contacted for details of other published and unpublished studies. SELECTION CRITERIA: This review was designed to include randomised controlled trials in which one treatment for asymptomatic retinal breaks and lattice degeneration was compared to another treatment or to no treatment. DATA COLLECTION AND ANALYSIS: One reviewer assessed the search results and collected relevant studies. Since no studies met the inclusion criteria, no studies were assessed for methodological quality. No data were extracted and no meta-analysis could be performed. MAIN RESULTS: No trials were found that met the inclusion criteria for this review. REVIEWER'S CONCLUSIONS: No conclusions could be reached about the effects of surgical interventions to prevent retinal detachment in eyes with asymptomatic retinal breaks and/or lattice degeneration. Some current recommendations for treatment, based upon a consensus of expert opinion, are contradicted by the best available evidence.

Humans↗
PubMed2000

Optic disk and retinal nerve fiber layer damage after transient central retinal artery occlusion: an experimental study in rhesus monkeys.

PURPOSE: To evaluate the retinal tolerance time to acute ischemic insult in middle-aged or elderly rhesus monkeys with pre-existing atherosclerosis and arterial hypertension. METHODS: In 39 eyes of 39 middle-aged and elderly rhesus monkeys with a mean age of 19.5 +/- 2. 8 years, occlusion of the central retinal artery was produced by temporary clamping of the central retinal artery at its site of entry into the dural sheath of the optic nerve for 97 to 300 minutes. Stereoscopic color fundus photography and fluorescein fundus angiography were performed before central retinal artery occlusion and serially thereafter. Retinal nerve fiber layer damage and optic disk changes were assessed by comparing morphometric evaluation of the color fundus photographs taken before central retinal artery occlusion and color fundus photographs taken at the end of the study. RESULTS: There was a significant correlation between duration of central retinal artery occlusion and decreased visibility of retinal nerve fiber layer (P =.018) and increasing optic disk pallor (P =. 014), and a trend between residual retinal circulation and decreased visibility of retinal nerve fiber layer (P =.085) and optic disk pallor (P =.162). However, there was a marked interindividual variation between the length of central retinal artery occlusion and degree of increased optic disk pallor and decreased visibility of the retinal nerve fiber layer, even among eyes with similar duration of central retinal artery occlusion. Complete or almost total optic nerve atrophy and nerve fiber damage were present in all eyes in which the duration of central retinal artery occlusion was 240 minutes or more. CONCLUSIONS: The findings of this study, compared with our previous study in young healthy rhesus monkeys, indicate that in middle-aged or elderly atherosclerotic and arterial hypertensive rhesus monkeys, central retinal artery occlusion for less than 100 minutes produced no apparent morphometric evidence of optic nerve damage; however, central retinal artery occlusion of 105 minutes but less than 240 minutes produced a variable degree of damage; central retinal artery occlusion for 240 minutes or more produced total or almost total optic nerve atrophy and nerve fiber damage.

Animals↗