Quadruple therapy leads to a sustained improvement of vision in patients with wet age-related macular degeneration.

AIM: To investigate the efficacy of a combined intravitreal therapy with prior photodynamic therapy (PDT) in patients with wet age-related macular degeneration. METHODS: Fifty-two patients (mean age: 72.7 years) with predominantly classic choroidal neovascularization received low-fluence PDT (42 J/cm2 for 72 s), followed 24 h later by a 0.4-ml core pars plana vitrectomy with intravitreal injection of dexamethasone (0.8 mg) and bevacizumab (1.25 mg). The best-corrected visual acuity (BCVA; 6 m Snellen), central macular thickness (optical coherence tomography), intraocular pressure and the need for retreatment were assessed. RESULTS: BCVA changed significantly (vs. baseline) at 3 months (+0.11), 9 months (+0.19) and 14 months (+0.16). At the end of the follow-up period, BCVA had improved by > 0.1 in the majority of the patients (72.9%), and the mean central retinal thickness had decreased by -44.3% (-211 µm). The retreatment rate was 25%. No increase in intraocular pressure or other adverse event was reported. CONCLUSIONS: The pharmacological effects of the drugs, the low-fluence PDT, and the physiological effects of the therapy may have contributed to the sustainability of the therapeutic benefits.

Content quality of ophthalmic information on the internet.

PURPOSE: Little is known whether information about eye conditions on the Internet is complete and accurate to support patient or layman decision making. METHODS: Quality of content modules about age-related macular degeneration (AMD) was analyzed on 20 web sites. Content analysis covered 72 criteria in 11 groups. Each single criterion was rated with '1' or '0' (yes/no answer). RESULTS: The interrater reliability between two observers was almost perfect (kappa = 0.86). On average, 25.6% (+/-15.6) of the criteria were fulfilled. In the categories diagnostic procedures, therapy, preventive checkups, prevention and prognosis of AMD, only 12.7, 18.3, 20.0, 25.0 and 30.0%, respectively, of the required content was given. CONCLUSION: Our study shows, based upon the example of university eye hospitals, that the full potential to provide laymen with firsthand and up-to-date information has by far not yet been achieved. Further research is needed on how the Internet influences the communication between patient and ophthalmologist.

Cataract surgery with implantation of an artificial lens.

BACKGROUND: Cataract surgery, the most frequently performed operative procedure worldwide, typically concludes with the implantation of an artificial intraocular lens (IOL) to correct aphakia (absence of the crystalline lens). METHOD: Selective literature review including current regulations, guidelines and recommendations for cataract surgery. RESULTS: The main symptom of cataract is loss of visual acuity, which usually progresses slowly. It can arise in one eye or both. There is a basic distinction between congenital and acquired cataracts. The probability of developing a cataract rises with age because of biochemical aging processes. The development of a cataract becomes highly likely from the sixth decade of life onward. CONCLUSIONS: As no effective medications for cataract are available at present, its current standard treatment is the removal of the clouded lens. In industrialized countries, this is usually done with ultrasound (phacoemulsification), followed by the implantation of an IOL.

Corneal re-epithelialization following phototherapeutic keratectomy for recurrent corneal erosion as in vivo model of epithelial wound healing.

BACKGROUND: This placebo-controlled double-blind study examined the suitability of recording corneal epithelialization after phototherapeutic keratectomy (PTK) as a model of epithelial wound healing. METHODS: Eighteen patients with recurrent corneal erosion were randomized into 2 groups, and received PTK with a 7-mm ablation zone. Postoperatively, one group was treated with an ointment containing 5% dexpanthenol and the other with the ointment vehicle without dexpanthenol. The epithelial lesions were recorded by digital slit-lamp photographs with fluorescein staining at fixed intervals until epithelial closure. The size of the epithelial defect was measured, and the average time until epithelial closure was calculated. Reliability of measurements was tested by calculating Cronbach's alpha from measurements at the same point in time. RESULTS: Photographs could be taken at all scheduled examinations. The measured size of the epithelial defects showed a high reliability (Cronbach's alpha = 0.994). The average time needed for epithelial closure was 57.5 h in the treatment group and 64.8 h in the placebo group (p = 0.177). CONCLUSIONS: Planimetric measurement of slit-lamp photographs of standardized epithelial defects is an adequate method for monitoring the progress of corneal epithelial wound healing. Although wounds treated with dexpanthenol showed a slightly shorter average healing time, the difference to the placebo was not significant.

Retinal vein occlusion and low-dose fibrinolytic therapy (R.O.L.F.): a prospective, randomized, controlled multicenter study of low-dose recombinant tissue plasminogen activator versus hemodilution in retinal vein occlusion.

PURPOSE: To investigate the efficacy of intravenous thrombolysis with low-dose recombinant tissue plasminogen activator (rt-PA) in recent-onset central retinal vein occlusion (CRVO) or branch retinal vein occlusion. METHODS: This was a prospective, randomized, controlled multicenter trial in patients with CRVO or branch retinal vein occlusion, best-corrected visual acuity < or =20/50, and onset of symptoms within 11 days before treatment. In each group, patients were randomized to either hemodilution or thrombolysis with 50 mg of rt-PA with concomitant intravenous heparinization. The primary clinical outcome measure was improvement in best-corrected visual acuity from baseline at 1 year. RESULTS: Fifty-two subjects were enrolled in the study. Patients with CRVO (n = 41) who were treated with rt-PA exhibited a significant improvement in best-corrected visual acuity compared with those who received hemodilution (P < 0.0001). At 1-year follow-up, the proportion of eyes with CRVO achieving an improvement in visual acuity of three or more lines was 45% after treatment with rt-PA and 21% after hemodilution therapy. The median final best-corrected visual acuity among CRVO patients given rt-PA was 20/60 (light perception, 20/15) compared with 20/400 (light perception, 20/20) in the hemodilution group. There were no significant differences among patients with branch retinal vein occlusion (n = 11). We observed no serious adverse events. No significant differences were found regarding the development of ocular neovascularization. CONCLUSION: Treatment with intravenous low-dose rt-PA improved visual outcome in CRVO. Thrombolysis was not associated with a lower risk of ocular neovascularization, indicating that the mechanisms involved in this process occur at an early stage.

Intrastromal keratotomy with femtosecond laser avoids profibrotic TGF-beta1 induction.

PURPOSE: To examine expression of the profibrotic cytokine TGF-beta1 after selective intrastromal corneal injury with the use of a femtosecond laser. METHODS: Rabbits underwent monocular intrastromal keratotomy at a preoperatively determined corneal depth of 160 to 200 mum with the use of a femtosecond laser. Femtosecond laser-induced TGF-beta1 expression was compared in nonoperated control eyes and eyes treated with photorefractive keratectomy (PRK). Follow-up examinations were performed 1, 3, 7, and 28 days after surgery. TGF-beta1 protein was identified by immunofluorescence labeling. With the use of laser-capture microdissection, epithelial, stromal, and endothelial cell layers were collected, and changes in TGF-beta1 mRNA expression were quantified with quantitative RT-PCR. RESULTS: TGF-beta1 mRNA and protein expression did not significantly increase after intrastromal femtosecond laser keratotomy. In contrast, TGF-beta1 was induced in corneal epithelial and stromal cells after PRK and showed up to 23-fold higher TGF-beta1 mRNA levels compared with control corneas. The increase of TGF-beta1 mRNA levels after PRK was accompanied by increased TGF-beta1 protein production. CONCLUSIONS: Isolated stromal injury with a femtosecond laser does not result in induction of the profibrotic cytokine TGF-beta1. Because TGF-beta1 has been implicated in a fibrotic response of the corneal stroma to injury, absence of TGF-beta1 induction argues for a favorable wound-healing response. These findings support highly selective intrastromal procedures in refractive surgery.

Transparency of information on eye diseases on the internet.

BACKGROUND: Transparency is an indicator of trustworthiness and quality of health information about eye diseases on the Internet. METHODS: 20 websites that contained information about eye diseases aimed at the general public were evaluated. A modified Afgis (Aktionsforum Gesundheitsinformationssystem/action forum health information system) project transparency checklist was used. RESULTS: On average, 6.15 +/- 1.68 criteria were fulfilled. All websites maintained separation between advertising and editorial content. Between 80 and 90% of the websites studied contained complete information about the provider, aims and target audience, and feedback from users. The criteria for privacy were met by 70% of websites, 40% met those for currency of content and data, 35% those for methods of quality assurance, 15% those for financing and sponsoring and 0% met the requirements for authors and sources of information. CONCLUSION: Visually impaired people benefit from transparency, because this facilitates accessibility to web-based health information. Hence, websites containing health information related to eye diseases should meet the demands of transparency.

Accessibility of health information on the internet to the visually impaired user.

PURPOSE: Web sites containing health information should be accessible to visually impaired persons. METHODS: 139 web sites containing medical information addressing laymen or patients were evaluated with respect to their accessibility. A quantitative checklist which is based upon the Web Content Accessibility Guidelines of the World Wide Web Consortium (W3C) was used. RESULTS: Only 18% (15 sites) achieved WAI (Web Accessibility Initiative) level A or AA. WAI level AA was reached by only 1% (1 site) of the web sites. None of the web sites reached level AAA; 82% of the assessed web sites offering consumer health information are not fully accessible to visually impaired persons. CONCLUSION: The accessibility of web-based health content to visually impaired users should be improved. Health information on the web should at least meet the requirements of priority 1 (level A), preferably priority 2 (level AA) of the W3C guidelines.

Influence of temporary hypothermia on corneal endothelial cell density during organ culture preservation.

PURPOSE: To evaluate temporary exposure to hypothermia for its effects on endothelial cell density of porcine corneas in dextran containing organ-culture medium, with regard to possible negative influences of low temperatures during the transport of corneal grafts. METHODS: Two groups of central discs from pig corneas (diameter 8 mm) were first organ-cultured (MEM with 6% dextran 500) for 24 hours at 32 degrees C. Twelve corneas were exposed to 4 degrees C in group 1 for 12 hours and to 21 degrees C in group 2 for 48 hours each. The paired corneal discs were not treated, and served as controls. After further organ culture of all corneas for 48 hours at 32 degrees C to allow regenerative processes, corneal endothelium was stained with alizarin red S and examined by light microscopy. The endothelial cell densities were determined manually on three central images. RESULTS: Exposure for 12 hours to 4 degrees C as well as for 48 hours to 21 degrees C induced an endothelial cell loss of 0.3% and 1.8% respectively. Statistical analysis showed no significant difference (p = 0.680) of the endothelial cell density between corneas exposed to 4 degrees C and the control corneas (4166 +/- 389 cells/mm(2) and 4177 +/- 407 cells/mm(2) respectively). Despite the minor cell loss, the difference of the endothelial cell density between corneas exposed to 21 degrees C and the control corneas (4085 +/- 260 cells/mm(2) and 4159 +/- 312 cells/mm(2) respectively) was statistically significant (p = 0.025). CONCLUSIONS: Exposure of organ-cultured porcine corneas in dextran containing medium to 4 degrees C for 12 hours and 21 degrees C for 48 hours does not compromise the endothelial cell density of donor corneas in a clinically relevant manner. A storage of corneal grafts at temperatures down to 4 degrees C for 12 hours, as might be the case during transport from the cornea bank to the ocular surgeon, does not seem to damage the endothelial cell layer.

Macular thickness after uneventful cataract surgery determined by optical coherence tomography.

BACKGROUND: Using standardized macular optical coherence tomography (OCT) in the postoperative period, subclinical changes in macular thickness can be detected. With this method, postoperative development of macular thickness in healthy eyes is evaluated. The repeatability of the method and the influence of selected surgical (phaco time and phaco energy) and biometric parameters (axial length and anterior chamber depth) on the results were assessed. METHODS: In a prospective study, 33 patients without macular pathology in both eyes were examined. Phacoemulsification and intraocular lens (IOL) implantation was performed in one eye, and the contralateral eye served as control. OCT (StratusOCT; Zeiss, Dublin, CA, USA), mean minimal foveal thickness (MMFT) and mean foveal thickness (MFT) were measured preoperatively, at 1 day, 1 week and 6 weeks postoperatively. At these visits, the best-corrected visual acuity (BCVA) tests and slit-lamp examination were performed. To assess the influence on foveal thickness ocular axial length, anterior chamber depth, phacotime and energy were documented. Statistical analysis using parametric tests was carried out with standard statistical software (SPSS11, BIAS). RESULTS: MMFT of the operated eyes and the intraindividual difference of MMFT increased significantly at one day (+12.31 +/- 24.2 microm, P < 0.001) and 6 weeks (+6.76 +/- 22.6 microm, P = 0.009). MFT in the operated eyes and intraindividual difference of MFT rose significantly at 1 day, 1 week and 6 weeks (1 day: +10.66 +/- 20.8 microm, P = 0,026; 1 week: +15.23 +/- 19.7 microm; 6 weeks: +17.33 +/- 14.81 microm, P < 0.001). Repeatability was better for MFT in controls (ICR = 0.92) than for MMFT in controls (ICR = 0.77). No clinical cystoid macular edema was diagnosed in this study. No correlation between macular thickening and visual acuity and selected surgical and biometrical parameters could be found. CONCLUSIONS: After cataract surgery, a mild increase of foveal thickness without impact on visual acuity could be observed. This increase may be due to both subclinical changes and to influence of changes in media opacity on the measurement technique. Surgical and biometric parameters such as phacotime and energy and axial length did not correlate to the degree of macular thickening.

Corneal femtosecond laser keratotomy results in isolated stromal injury and favorable wound-healing response.

PURPOSE: To examine the corneal repair response after intrastromal femtosecond (fs) laser keratotomy. METHODS: Twelve rabbits underwent monocular intrastromal keratotomy performed with an fs laser at a preoperatively determined corneal depth of 160 to 200 microm. The fs laser-induced corneal repair response was compared with that of nonoperated control eyes and eyes treated with photorefractive keratectomy (PRK). Follow-up examinations were performed 1, 3, 7, and 28 days after surgery. Corneas were evaluated using slit lamp, in vivo confocal microscopy, and light microscopy. The extracellular matrix components fibronectin and tenascin were located using immunofluorescence staining. Anti-Thy-1 and anti-alpha-SMA antibodies and phalloidin were used to identify repair fibroblasts. Cell proliferation and nuclear DNA fragmentation were detected using an anti-Ki-67 antibody and the TUNEL assay, respectively. RESULTS: Intrastromal fs keratotomy resulted in a hypocellular stromal scar discernible as a narrow band of increased reflectivity on slit lamp examination. Deposition of fibronectin and tenascin as well as death and subsequent proliferation of keratocytes were observed. No differentiation of keratocytes into Thy-1- or alpha-SMA-positive fibroblasts could be detected. In contrast, after PRK, which causes epithelial and stromal wounding, all markers for repair fibroblasts were found in subepithelial stromal layers. On slit lamp examination, a fibrotic scar and a corneal haze were revealed. CONCLUSIONS: Isolated stromal injury using an fs laser avoids epithelial injury and is associated with a favorable wound-healing response preserving corneal transparency. Thus, fs laser keratotomy is a highly selective laser treatment that can be useful for the treatment of refractive errors.

Endothelial cell density in porcine corneas after exposure to hypotonic solutions.

PURPOSE: To evaluate exposure to sucrose solution (1.8%) and hypotonic balanced salt solution (BSS) for its effects on endothelial cell density of porcine corneas. METHODS: Two groups of central discs from pig corneas were organ-cultured for 24 h. Twelve corneas per group were exposed to sucrose solution (1.8%) or hypotonic BSS for 4 min each. The paired corneal discs were not treated and served as controls. After further organ culture with and without dextran for 48 h, corneal endothelium was stained with alizarin red and examined by light microscopy. The endothelial cell densities were determined manually on three central images. RESULTS: The endothelial cell density differed significantly between corneas exposed to sucrose and the control corneas (3982+/-382 cells/mm(2) and 4360+/-331 cells/mm(2) respectively, and 3876+/-364 cells/mm(2) versus 4374+/-168 cells/mm(2) respectively with 6% dextran). In contrast, the endothelial cell density did not differ significantly between corneas exposed to hypotonic BSS and the control corneas (4374+/-296 cells/mm(2) and 4317+/-193 cells/mm(2) respectively, and 4348+/-151 cells/mm(2) versus 4426+/-175 cells/mm(2), respectively with 6% dextran). CONCLUSIONS: Exposure to 1.8% sucrose for 4 min induces a significant endothelial cell loss of 10% on average, whereas exposure to hypotonic BSS did not significantly influence the endothelial cell density.

Correlation between clinical in vivo confocal microscopic and ex vivo histopathologic findings of Salzmann nodular degeneration.

PURPOSE: To report clinical, in vivo confocal microscopy and ex vivo histopathologic findings of Salzmann nodular degeneration (SND). METHODS: A 48-year-old woman with symptoms of ocular irritation and decreased visual acuity caused by SND in both eyes was treated by corneal scraping and phototherapeutic keratectomy (PTK). Slit-lamp biomicroscopy, in vivo confocal microscopy, ex vivo light microscopy, immunohistology, and corneal topography were performed. RESULTS: In vivo confocal microscopy showed an irregular network of highly reflective structures representing activated keratocytes, which could be seen by light microscopy and characterized immunohistologically as myofibroblasts. Unstructured areas with increased reflectivity correlated with irregularly arranged collagen fibers and hyaline deposits in the nodulus. Epithelial cells in vivo appeared atypically shaped and elongated. These observations were consistent with decreased thickness of the epithelium over the nodules showed by histopathology. Treatment led to a dramatic reduction of hyperopia. Two months after surgery, uncorrected visual acuity (UCVA) in the right eye was 20/32 and 20/20 with a refraction of -0.75 -0.75/0 degrees. UCVA in the left eye was 20/40 and 20/20 with a refraction of +0.50 -1.75/165 degrees. Corneal topography showed regular astigmatism. CONCLUSION: In vivo confocal microscopy confirmed the clinicopathologic findings of Salzmann's nodular degeneration. Observations by in vivo confocal microscopy were consistent with the histopathologic descriptions of SND.

Training the adult amblyopic eye with "perceptual learning" after vision loss in the non-amblyopic eye.

We recently reported acuity development in the amblyopic eye of a 60-year-old patient after loss of vision in her non-amblyopic eye. Here, we focus on the training that we implemented, based on new insights from psychophysical procedures aiming at functional visual improvement of adults ("perceptual learning"). We alternately used the following procedures: grating acuity (Teller-Cards); contrast sensitivity (Vistech-Charts); two spatial localization tests (vertical alignment, pointing); and labyrinth patterns for a eye-hand coordination exercise. One month without intervention was followed by six months of training and two blocks of pleoptic treatment. Clinical parameters were assessed monthly. Besides acuity gain, we observed enhanced grating resolution and contrast sensitivity, decreased alignment distortions, pointing shifts, mainly after pleoptics, and more efficient labyrinth tracing. A questionnaire reflected the patient's perception of the changes. These data confirm the plasticity of the adult amblyopic system, be it spontaneous due to the loss of the non-amblyopic eye or caused by the intervention or both. Further experience is necessary to isolate the role of the intervention. Our results also underline the limitation of adult plasticity, emphasizing the importance of early diagnosis and treatment of amblyopia.

Pigment-epithelium-derived factor is upregulated in photocoagulated human retinal pigment epithelial cells.

There is much evidence that pigment-epithelium-derived factor (PEDF) is a potent antiangiogenic cytokine which inhibits retinal and choroidal neovascularization by inducing apoptosis in activated vascular endothelial cells. Furthermore, the regulation of PEDF appears to be linked to the regulation of vascular endothelial growth factor (VEGF), one of the most potent inducers of intraocular neovascularization. Previous studies have established that thermal photocoagulation, the mainstay in the therapy of various neovascular diseases of the posterior segment, results in a decrease in intraocular concentrations of VEGF and other angiogenic growth factors, thereby inhibiting active retinal neovascularization. In the current study, we sought to determine whether thermal photocoagulation has the potential to regulate the expression of PEDF in human retinal pigment epithelial (RPE) cells. Cultures of RPE cells were photocoagulated with a 532-nm diode laser. Subsequently, RNA was isolated for RT-PCR, and whole-cell extracts and precipitated cell culture supernatant were subjected to Western blot analysis. According to our results, PEDF mRNA and protein are significantly upregulated after photocoagulation. Moreover, PEDF protein was found to be secreted in the cell culture medium.

Three-dimensional rotational dacryocystography for imaging of the lacrimal draining system and adjacent anatomical structures.

PURPOSE: A three-dimensional (3D) rotational angiography system was used to perform 3D dacryocystography (3DRD) as an adjunct to the conventional dacryocystography assisted by digital subtraction angiography (DSA). METHODS: In 15 patients with severe epiphora, 3DRD was performed after inconclusive results from DSA-assisted dacryocystography. RESULTS: 3DRD was technically feasible and well tolerated in all 15 cases. In 5 out of 15 patients, 3DRD, in contrast to DSA-assisted dacryocystography, distinguished clearly between stenotic lesions of the canaliculi, lacrimal sac or nasolacrimal duct. In 10 cases, the simultaneous display of tear ducts and adjacent structures of the nasal cavity provided critical anatomical information for decision making between endoscopic and open dacryocystorhinostomy. CONCLUSIONS: 3DRD is technically feasible and adds important information to conventional DSA-assisted dacryocystography.

Unilateral exophthalmos associated with severe fibrous dysplasia.

Fibrous dysplasia is a benign developmental anomaly of bone, often affecting craniofacial bones. We report on a 9-year-old boy, who presented for routine checkup. Clinical examination revealed unilateral exophthalmos of his left eye without decrease of visual acuity or double vision. Radiologic studies showed characteristic extensive changes of fibrous dysplasia involving the left frontal bone, left orbital bones, maxillary and sphenoid bones. The patient was started on conservative therapy and the condition of the affected eye remained stable. As fibrous dysplasia of the orbital bones can be a cause of significant dysfunction and a treatable cause of blindness, early diagnosis is very important. These patients are most likely to present with complaints of facial asymmetry, including axial, vertical, or horizontal displacement of the globe, or visual loss. Therefore the ophthalmologist plays an important role in the early diagnosis of fibrous dysplasia.

Visual improvement during psychophysical training in an adult amblyopic eye following visual loss in the contralateral eye.

BACKGROUND: Recent publications have demonstrated neural plasticity in adult amblyopes subjected to psychophysical training based on perceptual learning. The purpose of this case report is to present rarely available prospective data of visual acuity development in a strabismic amblyope undergoing psychophysical training and pleoptic treatment after loss of function of the non-amblyopic eye. METHODS: The design is a prospective, observational and interventional case report. Visual acuity was tested monthly, with constant optical correction. The 60-year-old female patient participated in a psychophysical training implemented in our laboratory, and in pleoptic treatment. RESULTS: Slow functional improvement of the amblyopic eye was observed during a period of 10 months, both in the tests used for training and in visual acuity: single optotypes increased by 4 chart lines, crowded optotypes by 2-3 lines. CONCLUSIONS: To our knowledge, this is the first report of the new approach of perceptual learning in an adult amblyope after loss of vision in the contralateral eye. Our results represent further evidence that the visual system of adult amblyopes preserves a certain degree of neural plasticity, whether spontaneous or enhanced by training. Furthermore, that plasticity in adults is limited, and early diagnosis and treatment of amblyopia must remain the primary goal.

Pigment epithelium endoscopic laser surgery for treatment of choroidal neovascularization.

PURPOSE: To present a new concept and technique for subretinal surgery. METHODS: Twenty-four eyes of 24 patients with subfoveal choroidal neovascularization (CNV) were included in this study. Nine patients were operated on in Mexico City by one surgeon, 15 patients in Frankfurt by another surgeon. The retina at the posterior pole was detached and subretinal thermal photocoagulation of the CNVs was performed using a 20/19-gauge GRIN rod laser endoscope (Insight Instruments Inc., Sanford, Fla., USA). This procedure was termed PEELS (pigment epithelium endoscopic laser surgery). RESULTS: In 7 patients (Mexico), moderate improvement or stabilization of vision over 6 months or longer was achieved. In 10 out of 12 patients (Frankfurt), stabilization of vision over a follow-up period of 6-18 months was achieved, at least. Serious complications were not observed. Four of the Frankfurt series patients improved their vision. CONCLUSION: PEELS can stabilize or improve vision.

Factor XII deficiency: a thrombophilic risk factor for retinal vein occlusion.

PURPOSE: Factor XII deficiency is among the coagulation disorders that have been implicated in major thromboembolic events. However, little is known about an association of this coagulation disorder and retinal vessel occlusion. In the current study, we investigated the prevalence of factor XII deficiency in patients with retinal vein occlusion (RVO) with reference to age and cardiovascular risk factors. DESIGN: Cross-sectional study. METHODS: A cohort of 150 consecutive patients with central or branch retinal vein occlusion and 135 subjects matched for age and gender were prospectively screened for factor XII deficiency. Both cohorts were divided into two subgroups (<= 45 or >45 years), depending on the patients' age at the time of the RVO or a previous thromboembolic event. RESULTS: Overall, factor XII deficiency was found to be present in 14 (9.3%) of 150 patients and in 1 (0.7%) of 135 controls (P =.0009). Patient age <= 45 years at the time of the RVO or a previous thromboembolic event was associated with a high prevalence of factor XII deficiency (18%). By contrast, only 5 (5%) of 100 patients >45 years (P =.016) and none of the young controls (P =.0001) tested positive for factor XII deficiency. The prevalence among patients >45 years was similar to that found in age-matched controls (2%; P =.66). CONCLUSIONS: Our results indicate that factor XII deficiency is highly prevalent in RVO patients <= 45 years of age. By contrast, the prevalence of factor XII deficiency in RVO patients older than 45 years appears to be similar to that seen in healthy individuals.