Bilateral involvement by age related maculopathy lesions in a population

AIMS—To describe the influences of age and sex on the frequency of bilateral age related macular degeneration (AMD) and age related maculopathy (ARM) lesions.
METHODS—The Blue Mountains Eye Study examined 3654 older Australians, 82% of permanent residents living in an area west of Sydney. Stereo macular photographs were graded for AMD (neovascular maculopathy and geographic atrophy) and early ARM lesions (soft drusen, reticular drusen, hyperpigmentation, and hypopigmentation).
RESULTS—Among 230 gradable cases of AMD or early ARM, 183 (80%) were bilateral. For AMD, 39/69 cases (57%) were bilateral, while for early ARM, 123/161 cases (77%) had signs in both eyes. Of the individual lesions, reticular drusen (91%) and indistinct soft drusen (79%) were most frequently present in both eyes. Geographic atrophy was bilateral in 56%, neovascular AMD in 40%, and distinct soft drusen in 47%, while hyperpigmentation was bilateral in 38% and hypopigmentation in only 28% of cases. A consistent age related increase in bilateral distribution was observed for most lesions. After adjusting for effects of age, current smoking, and AMD family history AMD and ARM component lesions, except for soft drusen, were more frequently bilateral in women. This sex difference was significant only for neovascular AMD, odds ratio 7.7 (95% confidence intervals 1.3-46.7). An AMD family history was more frequently reported in cases with bilateral involvement.
CONCLUSIONS—This study has documented differences in the age related bilaterality of individual ARM components with higher bilateral rates for reticular or indistinct soft drusen compared with other lesions. The increased bilaterality of most ARM lesions among women is likely to contribute to the increased age adjusted risk of AMD blindness found in women.

Keywords: age related maculopathy; age related macular degeneration; drusen     

Decreased choriocapillaris perfusion following surgical excision of choroidal neovascular membranes in age-related macular degeneration

AIMS/BACKGROUND—To evaluate macular changes following surgical excision of subfoveal choroidal neovascular membranes (CNVs) in age-related macular degeneration (AMD).
METHODS—The clinical records, fluorescein angiograms, and CNV histopathology of 12 patients with AMD who underwent surgical excision of subfoveal CNV were reviewed.
RESULTS—New areas of decreased choriocapillaris perfusion were noted by fluorescein angiography in the previous location of the CNV in 8/12 (75%) cases. Surgically excised tissue contained retinal pigment epithelium (RPE) in 11/11 specimens and choriocapillaris in 1/11 specimen studied.
CONCLUSIONS—Choriocapillaris atrophy may partly underlie the limited visual outcome following subfoveal surgery for AMD. Abnormal choriocapillaris perfusion following CNV excision may be due to pre-existing choriocapillaris atrophy, to choriocapillaris damage or removal at the time of surgery, or to RPE removal at surgery with abnormal RPE repopulation of the dissected area and subsequent choriocapillaris degeneration.

     

Blood flow velocity in the extraocular vessels in chronic smokers

AIMS—To determine blood flow velocity in the extraocular vessels in healthy, chronic smokers and to compare these blood flow velocities with those of healthy non-smokers.
METHODS—In 46 healthy chronic smokers and 189 healthy non-smokers, peak systolic velocity (PSV), end diastolic velocity (EDV), and the resistivity index (RI) were measured in the ophthalmic artery (OA), central retinal artery (CRA), lateral short posterior ciliary artery (LPCA), and medial short posterior ciliary artery (MPCA) by means of a colour Doppler device, Siemens Quantum 2000.The maximal (max) and minimal (min) velocities were measured in the central retinal vein (CRV). Only one eye was measured in each subject, and right and left eyes were chosen randomly. Blood flow velocities were compared with one way MANOVA and t tests. The influence of age, sex, systolic and diastolic blood pressure, as well as heart rate on blood flow velocity and RI were evaluated by an analysis of covariance. The potential differences of the influence of the covariables on blood flow variables in smokers and non-smokers were tested by calculating the interactions.
RESULTS—In the majority of measured vessels blood flow velocity was higher in smokers than in non-smokers. This difference was statistically significant in the OA, CRV, and LPCA. The RI indices were equal or slightly lower in smokers. Furthermore, smokers had significantly lower systolic and diastolic blood pressure. Heart rate was higher in smokers but this difference did not reach statistical significance.
CONCLUSIONS—Colour Doppler measurements may differ significantly in smokers compared with non-smokers. Therefore, smoking habits should be considered when interpreting colour Doppler imaging results, and comparing different groups of diseased or healthy subjects.

     

Clinicopathological correlation of primary and recurrent choroidal neovascularisation following surgical excision in age related macular degeneration

AIMS/BACKGROUND—Fluorescein angiography and histopathological findings were correlated in two patients with recurrent choroidal neovascular membranes (CNVs) in an attempt to gain insight into the possible causes of recurrent CNVs and into the healing response after CNV excision.
METHODS—Two patients with recurrent CNVs underwent repeat excision, and the excised tissue was studied with light and electron microscopy.
RESULTS—Incomplete CNV excision probably led to the recurrences. The portion initially excised appears to have been anterior to the RPE in case 1. In both cases, recurrent CNVs contained RPE-like cells suggesting that native RPE can repopulate the dissection bed. The tissue excised at the second operation contained areas with hyperplastic RPE and fragments of Bruch's membrane (external to the RPE basement membrane) in a matrix of fibrillar collagen and fibrocytes, suggesting that initial removal of the CNV can be followed by an abnormal anatomical arrangement of RPE and scarring of Bruch's membrane.
CONCLUSIONS—Abnormal resurfacing of the dissection bed by RPE and fibroblasts may underlie, in part, the limited visual outcome often seen after surgical excision of CNVs in age related macular degeneration.

Keywords: age related macular degeneration; choriocapillaris atrophy; choroidal neovascularisation; fluorescein angiography     

Effect of breathing 100% oxygen on retinal and optic nerve head capillary blood flow in smokers and non-smokers

AIM—The effect of breathing 100% oxygen on retinal and optic nerve head capillary blood flow in smokers and non-smokers was investigated using scanning laser Doppler flowmetry (SLDF) as a new non-invasive method to visualise and quantify ocular blood flow.
METHOD—10 eyes of 10 young healthy non-smoking volunteers (mean age 26 (SD 3) years) and nine eyes of nine young healthy smoking volunteers (mean age 26 (4) years) were investigated. All participants were asked not to smoke or consume caffeine containing drinks for at least 4 hours before the measurements. Blood flow measurements were performed before and after 100% oxygen was applied to the subjects through a mask over a period of 5 minutes (6 litres per minute). Juxtapapillary retinal and optic nerve head blood flow were determined in arbitrary units using SLDF representing a combination of laser Doppler flowmetry and a scanning laser system allowing visualisation and quantification of the retinal and optic nerve head blood flow. Blood flow was determined in an area of 100 µm × 100 µm. The level of carboxyhaemoglobin was determined in all subjects. A Wilcoxon matched pairs signed ranks test (non-parametric) was used for statistical evaluation.
RESULTS—In the non-smoking group, retinal `flow' was reduced by 33% (p = 0.005), optic nerve head `flow' by 37% (p = 0.005). In the smoking group retinal flow was reduced by 10% (p = 0.01), optic nerve head flow by 13% (p <0.008). The difference in reactivity to oxygen breathing between smokers and non-smokers was highly significant (p <0.00001). Increased carboxyhaemoglobin levels were not found in either of the groups. A significant reduction of the mean arterial blood pressure of 6% (5%) (p <0.02) was observed in the non-smoking group after administration of oxygen.
CONCLUSION—These results indicate that hyperoxia leads to a decrease in capillary blood flow of the retina and optic nerve head secondary to vasoconstriction, and that smokers do not respond to oxygen breathing as non-smokers do. The findings might be based on factors such as long term effects of nicotine on the sympathetic and parasympathetic nervous system.

     

Increased expression of angiogenic growth factors in age-related maculopathy

AIMS/BACKGROUND—The late stages of age-related maculopathy (ARM), especially neovascular macular degeneration (ARMD), can severely affect central vision and are the main cause of blindness in the elderly in the Western world. It has been shown that angiogenic growth factors are present in neovascular membranes in ARMD. However, it is not known if angiogenic growth factors play a role in the onset of neovascularisation.
METHODS—In order to elucidate the involvement of angiogenic growth factors in the initiation of neovascularisation in early stages of ARM, the expression patterns of VEGF, TGF-β, b-FGF, and PDGF-AA on 18 human maculae with ARM, and on 11 control specimens were investigated immunohistochemically.
RESULTS—A significantly increased expression of VEGF (p=0.00001) and TGF-β (p=0.019) was found in the retinal pigment epithelium (RPE) of maculae with ARM compared with control maculae. Furthermore, an increased expression of VEGF and PDGF was found in the outer nuclear layer of maculae with ARM.
CONCLUSION—These results demonstrate an increased expression of VEGF in the RPE, and in the outer nuclear layer in maculae with ARM, that could be involved in the pathogenesis of neovascular macular degeneration. Furthermore, enhanced TGF-β expression in the RPE cells of maculae with early stages of ARM was shown.

     

Effect of cigarette smoking on copper, lead, and cadmium accumulation in human lens

AIM—To identify cigarette smoking as a risk factor for development of cataract, to determine the importance of copper, lead, and cadmium in cataractogenesis, and to learn about any relation between those elements.
METHODS—Copper, lead, and cadmium concentrations were measured by atomic absorption spectrophotometry in 37 cataractous and nine normal human lenses.
RESULTS—All three element accumulations in lenses with cataract were statistically meaningful. Lenticular copper, lead, and cadmium were increased significantly with cigarette smoking. Cadmium had a positive correlation both with lead and copper in cataractous lenses.
CONCLUSION—The accumulation of copper, lead, and cadmium occurs in cataract. The probable source of cadmium in humans is cigarettes. Lenticular cadmium accumulation also increases copper and lead precipitation in the lens. Cigarette smoking might be cataractogenic.

Keywords: cigarettes; cataract; copper; lead; cadmium     

Knowledge, attitudes, and self care practices associated with age related eye disease in Australia

AIM—To determine the level of correct knowledge about common eye disease and attitudes towards blindness prevention and treatment, and how these factors influence self care practices in a population based sample.
METHODS—A cluster random sample of the Victorian population was interviewed. The study population comprised residents aged 40 years of age or older living in five randomly selected Melbourne metropolitan suburbs and four randomly selected rural areas of Victoria. Questions were asked to ascertain each person's knowledge of common age related eye disease—that is, cataract, age related macular degeneration (AMD), and glaucoma. A subsample of the population was also asked questions to determine their attitudes to blindness prevention and treatment. All respondents were asked the year of their last visit to an eye practitioner.
RESULTS—A total of 3184 (89%) eligible residents were assessed. Sex (females), age (younger people), higher levels of education (secondary, trade, or tertiary education), recent visit to an eye practitioner (within the past 2 years) and English spoken at home appeared to be significant predictors of knowledge of common age related eye conditions. Younger people believed blindness prevention and blindness treatment were the highest priorities compared with other diseases; people who spoke English at home and people with knowledge of common age related eye disease also considered blindness treatment to be the highest priority compared with other diseases. People with a previous diagnosis of age related eye disease, older people, females, people with correct knowledge of common eye diseases, and those who spoke English at home were significantly more likely to be under eye care. No interaction was found between knowledge and positive attitudes to self care practices.
CONCLUSION—These data show that there is a large gap in the public's knowledge and understanding of eye disease that will need to be understood for eye health promotion activities.

Keywords: knowledge; attitudes; eye diseases; cross sectional studies     

Scanning laser fundus perimetry before laser photocoagulation of well defined choroidal neovascularisation

AIM—To assess the centre of fixation before laser photocoagulation of well defined juxtafoveal or extrafoveal choroidal neovascularisation (CNV) secondary to age related macular degeneration (AMD), and to better predict visual function after treatment using scanning laser ophthalmoscope (SLO) fundus perimetry.
METHODS—19 consecutive eyes with juxtafoveal or extrafoveal CNV were examined by fundus perimetry before and after laser treatment with documentation of the fixation point using the SLO. The stability of fixation was defined as standard deviation around the mean fixation point. Overlays of fluorescein angiographic pictures and fundus perimetry were obtained using image analysis software.
RESULTS—Fundus perimetry allowed accurate determination of the centre of fixation. Overlays demonstrated the precise geographic relation of the angiographically detectable foveal margin of the CNV and the centre of fixation. Thereby, prediction of the visual outcome with regard to reading ability was facilitated. Stability of fixation did not change significantly after treatment.
CONCLUSIONS—Fundus perimetry using the SLO was helpful in patients who underwent laser treatment for juxtafoveal or extrafoveal CNV secondary to AMD and may aid the pretreatment counselling of such patients.

     

Risk of endophthalmitis after cataract extraction: results from the International Cataract Surgery Outcomes study

AIM—To estimate risk of infectious endophthalmitis after cataract extraction in Denmark and to compare results with the risk of this complication in the USA
METHODS—In the national Danish administrative hospital register, 19 426 patients were identified who underwent first eye cataract surgery from 1985 to 1987 and who were 50 years of age or older. Of these, 61 patients had postoperative endophthalmitis.
RESULTS—A 12 month cumulative risk of rehospitalisation for endophthalmitis was estimated at 0.18% (95% CI 0.09-0.26) after extracapsular cataract extraction with lens implant. Advanced age, male sex, intracapsular cataract extraction, and anterior vitrectomy were all associated independently with an increased risk of postoperative endophthalmitis. When restricting the sample to patients aged 65 years or older, in order to allow comparisons to be made with the US National Study of Cataract Outcomes, a 12 month risk of 0.17% (95% CI 0.08-0.25) was estimated. The previously reported US risk of 0.12% is included in the confidence interval of the risk estimated in the Danish sample.
CONCLUSION—Despite considerable differences in the healthcare systems, no statistically significant difference in outcome of surgery as measured by risk of endophthalmitis was shown between Denmark and the USA.

     

Aging changes of the optic nerve head in relation to open angle glaucoma

AIMS—To determine the age related changes in optic nerve head structure in a group of normal subjects and assess the significance of any changes in relation to those found in open angle glaucoma.
METHODS—A group of 88 white volunteers and friends and spouses of patients with a normal visual field and normal intraocular pressure was studied. Two different imaging and measurement devices were used (computer assisted planimetry and scanning laser ophthalmoscopy), and the results from each were compared. Measurements were made of the optic disc, optic cup, and neuroretinal rim areas, and the vertical optic disc diameter and cup/disc diameter ratio.
RESULTS—Neuroretinal rim area declined at the rate of between 0.28% and 0.39% per year. Vertical optic cup diameter and optic cup area increased with age. The mean cup/disc diameter ratio increased by about 0.1 between the ages of 30 and 70 years.
CONCLUSIONS—Age related changes are significant and measurable, and should be taken into account when assessing the glaucoma suspect, and when estimating the rate of progression of glaucomatous optic neuropathy in patients with established disease.

     

Thermolabile MTHFR genotype and retinal vascular occlusive disease

BACKGROUND—Raised levels of total plasma homocysteine (tHcy) are associated with an increased risk of retinal vascular occlusive disease. A thermolabile form of a pivotal enzyme in homocysteine metabolism, methylenetetrahydrofolate reductase (MTHFR), has been associated with vascular occlusive disease and raised tHcy levels. The relation between thermolabile MTHFR genotype, tHcy, and retinal vascular occlusive disease has not been determined.
METHODS—A retrospective case-control study involving hospital based controls and cases with retinal vascular occlusions in whom tHcy levels had been determined was undertaken. Genotyping for the MTHFR 677 C-T mutation that specifies the thermolabile form of the enzyme was performed by established methods in all subjects. The relation between homozygosity for thermolabile MTHFR genotype (TT), raised tHcy levels, and risk of retinal vascular occlusive disease was examined.
RESULTS—87 cases of retinal vascular occlusive disease (mean age 68.7 years) comprising 26 cases of retinal artery occlusion and 61 of retinal vein occlusion were compared with 87 controls (mean age 70.2 years). The TT genotype did not confer a significantly increased risk of retinal vascular occlusive disease. The mean tHcy level was significantly higher in the cases than in the controls (p<0.0001). Overall, and in both the cases and controls, the frequency of the TT genotype was higher in those with normal tHcy levels than in those with increased levels of tHcy. However, the TT genotype did not significantly alter the risk of increased tHcy levels in these patients.
CONCLUSIONS—The TT genotype is not associated with an increased risk of retinal vascular occlusive disease or increased tHcy levels in this group of elderly patients. In older patients, nutritional rather than genetic factors may be more important in increasing tHcy levels, a known risk factor for retinal vascular occlusive disease.

     

Ultrasound biomicroscopic measurement of anterior chamber angle in premature infants

AIM—To establish normative values for the anterior segment in premature infants in relation to postconceptional age and birth weight.
METHODS—Anterior segments were measured in 39 premature infants, 25 to 39 weeks' gestational age by use of ultrasound biomicroscopy and a muscle hook with topical anaesthesia.
RESULTS—Anterior chamber depth, trabecular-iris angle, angle opening (trabecular-iris) distances at 250 and 500 µm from the scleral spur, and the thickness of the thickest part of the iris showed linear increases in relation to postconceptional age and birth weight.
CONCLUSIONS—Ultrasound biomicroscopy is a powerful tool for obtaining precise images and measurement of the anterior segment in preterm neonates. Normative values were established for anterior segment dimensions in relation to postconceptional age and birth weight.

     

Influence of patient age on refraction and corneal haze after photorefractive keratectomy

AIMS/BACKGROUND—Since wound healing processes are known to be more rapid in those who are young, it was decided to examine the effect of patient age on refractive outcome of photorefractive keratectomy (PRK).
METHODS—The records of 599 eyes that had undergone PRK were studied retrospectively. The eyes were categorised by baseline myopia and patient age. Spherical equivalent and corneal haze were compared in the baseline refraction and age groups at 3, 6, and 12 months after PRK.
RESULTS—There were no differences in postoperative refraction and corneal haze in the different age groups.
CONCLUSION—Patient age had no statistically significant effect on refraction and corneal haze 1 year after PRK.

     

Ocular changes associated with Giardia lamblia infection in children

BACKGROUND—The protozoan disease giardiasis can cause ocular complications, including "salt and pepper" retinal changes.
METHODS—Ophthalmic examinations were performed in 141 children (mean age 4.7 (SD 2.0) years) with active or past giardiasis diagnosed on the basis of microscopic examination of stool specimens or duodenal secretions—53 were newly diagnosed and untreated (group A), 50 had active infections in spite of metronidazole therapy (group B), and 38 had been successfully treated, with negative stool specimens for 1-3 years (group C). 300 children with no evidence of giardiasis were used as controls.
RESULTS—Salt and pepper retinal changes (with normal electroretinographic findings) were diagnosed in 28 (19.9%) of the patients with giardiasis (11 from group A, 10 from group B, and seven from group C), including five pairs of siblings. In all subgroups, the children with retinal changes were consistently younger than those with normal retinas. In eight cases, the lesions could be visualised only with direct ophthalmoscopy.
CONCLUSION—Our findings indicate that asymptomatic, non-progressive retinal lesions are particularly common in younger children with giardiasis. This risk does not seem to be related to the severity of the infection, its duration, or the use of metronidazole but may reflect a genetic predisposition.

Keywords: gastrointestinal disease; Giardia lamblia; eye; retina     

Endogenous cortisol profile in patients with central serous chorioretinopathy

AIM—To study the endogenous cortisol levels in patients with central serous chorioretinopathy (CSCR).
METHODS—Endogenous cortisol levels in urine and plasma were determined in 30 patients with acute CSCR and compared with 30 age and sex matched controls.
RESULTS—The mean values of the 8 am plasma cortisol (29.97 µg/dl v 18.76 µg/dl), 11 pm plasma cortisol (22.03 µg/dl v 13.06 µg/dl), and 24 hour urine cortisol (11.01 mg/24 h v 7.39 mg/24 h) revealed significantly higher values in the patient group (p<0.001).
CONCLUSIONS—Increased levels of endogenous cortisol are present in patients with CSCR.

     

Pars plana vitrectomy with pars plana tube implantation in eyes with intractable glaucoma

AIMS—Intractable glaucoma is glaucoma resistant to medical therapy and conventional surgical procedures. In this study, a planned surgical technique is discussed for controlling the increased intraocular pressure in selected cases with intractable glaucoma.
METHODS—Total pars plana vitrectomy with pars plana tube implantation was performed in 17 eyes of 17 cases with intractable glaucoma. Patients with neovascular glaucoma were not included in this study. The mean age of these patients (seven men, 10 women) was 44.6 (SD 22.1) years and mean follow up period was 30.3 (15.5) months (range 4-71). Drainage implants with a disc were used in 16 cases, whereas, a tube with scleral buckle (Schocket surgery) was preferred in one case. An intraocular pressure below or equal to 20 mm Hg without any adjunctive medication or with only one type of antiglaucomatous drop was considered as an adequate operative outcome.
RESULTS—16 out of 17 eyes maintained adequate pressure control. Only three out of these 16 eyes required prophylactic antiglaucomatous medications. One patient underwent reoperation for pressure control. The most severe complications observed postoperatively were intravitreal haemorrhage (one case), choroidal detachment (one case), implant failure (one case), total retinal detachment (two cases), and corneal endothelial decompensation (five cases).
CONCLUSION—Pars plana placement of drainage tube following pars plana vitrectomy should be considered as an alternative method for controlling increased intraocular pressures in selected patients with intractable glaucoma.

Keywords: glaucoma; pars plana vitrectomy; pars plana tube implantation     

Randomised, controlled trial of spirometric changes in elderly people receiving timolol or betaxolol as initial treatment for glaucoma

AIM—To investigate respiratory and cardiovascular side effects in elderly people in the first 12 months after commencing topical β antagonists.
METHODS—40 patients (mean age 74 years) were recruited to a randomised, masked study. Spirometry, pulse, and blood pressure were recorded before, 1 month, and 12 months after starting topical therapy with either timolol 0.5% twice daily or betaxolol 0.5% twice daily.
RESULTS—After 1 month five of 20 patients allocated timolol and three of 20 given betaxolol had discontinued it for respiratory reasons, not always accompanied by symptoms. There were no significant differences in changes in mean values of spirometry, pulse, or blood pressure between groups. No further changes were made in therapy for respiratory reasons in the following year. One patient suffered a hypotensive stroke within 2 days of starting timolol.
CONCLUSIONS—By performing spirometry before starting topical β antagonist therapy and repeating it after 1 month most patients at risk of respiratory impairment can be identified.

Keywords: spirometry; elderly; timolol; betaxolol; glaucoma     

Incidence of delayed onset infection after trabeculectomy with adjunctive mitomycin C or 5-fluorouracil treatment

AIMS/BACKGROUND—The introduction of the adjunctive use of antiproliferatives to trabeculectomy has greatly improved the success rate of this operation. Trabeculectomy with antiproliferative treatment, however, is usually associated with a cystic and thin walled filtering bleb, which may be more susceptible to infection. The objective of this study was to evaluate the incidence, clinical findings, and risk factors of delayed onset, bleb related infection after trabeculectomy with adjunctive mitomycin C (MMC) or 5-fluorouracil (5-FU) treatment.
METHODS—The records of 632 glaucoma patients who underwent 966 trabeculectomies, with and without the use of adjunctive MMC or 5-FU treatment, between January 1985 and February 1995 were analysed. The mean follow up period was 3.5 (2.4) years (range 0.1 to 11.2 years). The mean patient age was 54.8 (18.8) years (range 0 to 88 years).
RESULTS—Bleb related infection occurred in one of 76 trabeculectomies that did not receive antiproliferatives (1.3%), three of 228 treated with 5-FU (1.3%) trabeculectomies, and seven of 662 treated with MMC (1.1%). Five eyes developed blebitis; six eyes developed endophthalmitis. Bleb related infection developed an average of 3.1 (1.6) (range 0.4 to 6.0) years after trabeculectomy. All eyes had avascular or hypovascular blebs that were cystic in shape before infection and all eyes had reduced intraocular pressure. Early wound leaks and chronic, intermittent bleb leaks were identified to be risk factors for the bleb related infection.
CONCLUSION—The incidence of delayed onset, bleb related infection after trabeculectomy with antiproliferative treatment is similar to that after trabeculectomy without antiproliferatives.

     

Activated protein C resistance in patients with central retinal vein occlusion

AIM/BACKGROUND—A new defect in the anticoagulant system has recently been discovered—activated protein C resistance. The frequency of this disorder has been shown to be increased in young patients (<50 years of age) with central retinal vein occlusion. This study was carried out to determine if there was any overrepresentation of activated protein C resistance in patients >50 years of age with central retinal vein occlusion.
METHODS—Blood samples were obtained from 83 patients >50 years of age and with a history of central retinal vein occlusion. The blood samples were analysed for activated protein C resistance with standard clinical laboratory methods.
RESULTS—In this material 11% of the patients were resistant to activated protein C. The normal incidence of activated protein C resistance in the same geographical area is 10-11%.
CONCLUSION—Activated protein C resistance does not seem to be a cause of central retinal vein occlusion in people older than 50 years.