Post-Keratoplasty Microbial Keratitis in the Era of Lamellar Transplants-A Comprehensive Review.

Microbial keratitis in a post-transplant cornea should be considered a distinct entity from microbial keratitis in a non-transplant cornea. Firstly, the use of immunosuppressive treatments and sutures in corneal transplants changes the etiology of keratitis. Secondly, corneal transplant has an impact on corneal biomechanics and structure, which facilitates the spread of infection. Finally, the emergence of lamellar transplants has introduced a new form of keratitis known as interface keratitis. Given these factors, there is a clear need to update our understanding of and management strategies for microbial keratitis following corneal transplantation, especially in the era of lamellar transplants. To address this, a comprehensive review is provided, covering the incidence, risk factors, causes, and timing of microbial keratitis, as well as both clinical and surgical management approaches for its treatment in cases of penetrating and lamellar corneal transplants.

Utilization of the Reinstein ICL Sizing Formula With Hand-held Ultrasound Biomicroscopy Measurements.

PURPOSE: To evaluate the accuracy of the Reinstein formula with hand-held ultrasound biomicroscopy (UBM) measurements for sizing of the Implantable Collamer Lens (ICL). METHODS: A total of 107 myopic eyes of 57 patients implanted with the ICL were included in the study. The size of the ICL was selected based on the manufacturer's recommendations. Agreement between the vault predicted by the Reinstein formula and the vault measured postoperatively was analyzed with Bland-Altman plots. RESULTS: A total of 95% and 81% of patients had a postoperative vault ranging from 150 to 1,000 and 250 to 750 µm, respectively. The mean vault predicted by the Reinstein formula and the postoperative vault in the current study were 580 ± 181 and 547 ± 200 µm, respectively. The size recommendations of the Reinstein formula and the formula provided by the manufacturer, the Kojima formula, and the Dougherty formula overlapped in 50%, 57%, and 49% of eyes, respectively. CONCLUSIONS: The results show that the Reinstein formula combined with a hand-held UBM provides reliable sizing predictions of the ICL. However, considering that robotic UBM measurements have demonstrated a narrower range of deviation in predicting vault depth in previous studies, a direct comparison study between robotic UBM and hand-held UBM measurements is necessary to fully assess the limitations of combining hand-held UBM with the Reinstein formula. [J Refract Surg. 2024;40(3):e142-e147.].

Ocular sarcoidosis in adults and children: update on clinical manifestation and diagnosis.

Sarcoidosis-associated uveitis, is the predominant ocular sarcoidosis presentation, which affects both adults and children. For adults, international ocular sarcoidosis criteria (IWOS) and sarcoidosis-associated uveitis criteria (SUN) are defined. However, for children they are not yet established internationally. Due to the specificity of pediatric manifestations of sarcoidosis, this task is even more challenging. In children, sarcoidosis is subdivided into Blau syndrome and early-onset sarcoidosis (BS/EOS) affecting younger children (< 5 years) and the one affecting older children with clinical presentation resembling adults. Differential diagnosis, clinical work-up as well as diagnostic criteria should be adapted to each age group. In this article, we review the clinical manifestation of sarcoidosis-associated uveitis in adults and children and the sensitivity and specificity of various ocular sarcoidosis diagnostic modalities, including chest X-ray and CT, FDG PET-CT, gallium-67 scintigraphy, bronchoalveolar lavage fluid, genetic testing for NOD2 mutations and serum biomarkers, such as ACE, lysozyme and IL2R.

Spherical aberrations and their role in modern ophthalmology.

Spherical aberration is an imperfection of the optical system of the human eye. The role of spherical aberration of the human eye in the quality of vision and pseudoaccommodation is reviewed. Spherical aberration is an imperfection of the optical system of the human eye. In most cases, due to well-developed neuroadaptation, it is insignificant for the perception of the image. Nevertheless, its role in modern ophthalmology is far from straightforward. On the one hand, there are clinical scenarios in which an excess of spherical aberration degrades the retinal image and leads to a high dissatisfaction rate among patients.©Recently, there is a growing interest in the modulation of spherical aberration in the clinical setting. Modern intraocular lenses as well as laser refractive procedures are aimed at interfering with spherical aberrations of the optical system in order to increase range of pseudoaccommodation. Here, we review the role of spherical aberration of the human eye in the quality of vision and pseudoaccommodation.

Effect of COVID-19 Lockdowns on Eye Emergency Department, Increasing Prevalence of Uveitis and Optic Neuritis in the COVID-19 Era.

Background: The COVID-19 pandemic led to the reorganization of the health care system. A decline in health- and life-saving procedures has been reported in various medical specialties. However, data on ophthalmic emergencies during lockdowns is limited. Methods: We conducted a retrospective, observational, case-control study of 2351 patients registered at the ophthalmic emergency department of a tertiary hospital in Poland during three national COVID-19 lockdowns (March/April 2020, November 2020, and March/April 2021) and corresponding months in 2019. Results: The total number of visits declined from a mean of 720/month in the non-COVID era to 304/month during COVID-19 lockdowns (p < 0.001). Ocular trauma incidence dropped significantly from 2019 (non-COVID months) to 2020/2021 (COVID group mean 201 vs. 97 patients monthly, respectively, p = 0.03). Of note, the percentage of foreign bodies removal was significantly higher during lockdowns than corresponding time in the non-COVID era. A downward trend for vitreous detachment and macular disorders cases was observed between COVID and non-COVID time. Uveitis and optic neuritis patients were seen more often during lockdowns (p < 0.001 and p = 0.0013, respectively). In contrast, the frequency of conjunctivitis and keratitis, potentially COVID-related problems, decreased significantly in COVID-19 time (mean 138 vs. 23 per month in non-COVID vs. COVID lockdowns, respectively, p < 0.001). Conclusions: The overall number of eye emergency visits declined during COVID-19 lockdowns. Conjunctivitis and keratitis rates dropped during the lockdowns. Interestingly, the frequency of immune-mediated ocular conditions (uveitis, optic neuritis) increased significantly which might be triggered by SARS-CoV2 infection.

Glaucoma patients have an increased level of trimethylamine, a toxic product of gut bacteria, in the aqueous humor: a pilot study.

PURPOSE: Animal studies suggest that gut bacteria metabolites are involved in regulation of intraocular pressure or development of glaucoma. However, clinical data are lacking. Here, we wanted to compare level of trimethylamine (TMA), an uremic toxin produced by gut bacteria, along with betaine and trimethylamine N-oxide (TMAO), a substrate and a product of its metabolism, in the aqueous humor and in plasma of patients with glaucoma and their controls. METHODS: Twenty patients were selected for cataract phacoemulsification, and 20 patients selected for phacotrabeculectomy were enrolled in the study. Patients were matched with controls on systemic diseases and estimated glomerular filtration rate. Blood samples were collected in the preoperative suite, whereas aqueous humor samples were collected as the first step of both procedures. Subsequently, level of betaine, TMA and TMAO was analyzed by means of chromatography. RESULTS: In the aqueous humor, level of TMA, but not betaine or TMAO, was significantly higher in the phacotrabeculectomy group than in the phacoemulsification group. Plasma level of betaine, TMA and TMAO was similar between groups. In both groups, level of betaine and TMA, but not TMAO, was significantly higher in plasma than in the aqueous humor. CONCLUSION: TMA, but not TMAO or betaine level, is increased in the aqueous humor of patients with glaucoma. TMA might play a role in pathogenesis of glaucoma; however, prospective studies are needed to confirm our findings.

Immersion Biometry for Intraocular Lens Power Calculation with Fourth-Generation Formulas.

BACKGROUND: Fourth-generation formulas for intraocular lens power calculations, including the Barrett Universal II formula, the Olsen formula or the Holladay 2 formula, were thoroughly validated with optical biometry measurements. They precisely predict the effective lens position not only in normal eyes but also in eyes with unusual anatomy. However, in the setting of dense nuclear or posterior subcapsular cataracts, optical biometers fail to obtain accurate measurements and third-generation formulas, i.e. the Hoffer Q or the SRK/T, combined with ultrasound measurements are a method of choice. Considering that optical biometry was fine-tuned to immersion ultrasound, we hypothesize that fourth-generation formulas will yield precise intraocular lens power calculations with immersion ultrasound measurements. METHODS: We retrospectively analyzed 50 eyes of 50 patients who underwent uneventful cataract surgery. All patients had intraocular lens power calculated based on immersion ultrasound measurements. Refractive error predictions were compared between third-generation formulas and fourth-generation formulas. RESULTS: There were no statistically significant differences in the median absolute error between formulas. In the study, 86%, 88%, 86%, 84%, 88% and 80% of eyes were within 1 D of target refraction for the SRK/T, the Barrett II, the Hoffer Q, the Holladay 1, the Holladay 2 and the Olsen formula respectively. CONCLUSION: Fourth-generation formulas combined with immersion ultrasound produced similar results to third-generation formulas. However, the percentage of eyes within 1 D of target refraction remains inferior to previously reported results for optical biometry measurements.

Valeric Acid, a Gut Microbiota Product, Penetrates to the Eye and Lowers Intraocular Pressure in Rats.

Mechanisms controlling intraocular pressure (IOP) and arterial blood pressure (BP) sharesimilar mediators, including gut bacteria metabolites. Here, we investigated the effects of valericacid (VA), a short chain fatty acid produced by microbiota from undigested carbohydrates, on IOPand BP. To test if gut VA penetrates to the eye we evaluated eyes' homogenates after theadministration of D9-VA into the colon. Additionally, the following experimental series wereperformed on 16-week-old Sprague Dawley rats to analyze the influence of VA on IOP: vehicletreatment; VA treatment; VA + hydroxybutyrate - a short chain fatty acids' G protein-coupledreceptor 41/43 (GPR 41/43) blocker (ANT); hydroxybutyrate; VA + angiotensin II; angiotensin II; VAtreatment in rats with superior cervical ganglion excision and sham operated rats. D9-VA rapidlypenetrated from the colon to the eye. VA significantly decreased IOP and BP. The decrease in IOPwas gradual and lasted through the experiment. In contrast, a decrease in BP was instantaneous andlasted no longer than 10 min. Angiotensin II, ANT, and sympathetic denervation did not influencethe effect of VA on IOP. In conclusion, colon-derived VA penetrates to the eye and decreases IOP.The effect is independent from BP changes, angiotensin II, GPR41/43, and sympathetic eyeinnervation.

Performance of the Barrett Toric Calculator with and without measurements of posterior corneal curvature.

BACKGROUND: Toric intraocular lens power calculators, e.g., the Barrett Toric Calculator, based on predicted, rather than on measured posterior corneal curvature have yielded the best results so far. However, recent update of the Barrett Toric Calculator aims to fine tune its refractive predictions with the input of measured posterior corneal curvature. Here, we wanted to compare refractive predictions of the Barrett Toric Calculator, based on IOL Master 700 biometry, with and without measurements of posterior corneal curvature. METHODS: In total 30 eyes were included in the study. One-month postoperative manifest refraction and predicted residual refractive error of both formulas were utilized to calculate mean absolute error and centroid error in predicted residual astigmatism. The Pentacam was used to measure posterior corneal curvature. RESULTS: We did not find any statistically significant difference in mean absolute error and centroid error in predicted residual astigmatism between the Barrett Toric Calculator with and without measurement of posterior corneal curvature. Post-hoc analysis of with-the-rule and against-the-rule astigmatic eyes did not reveal any significant differences as well. CONCLUSIONS: Astigmatism prediction errors, based on IOL Master 700 biometry, with and without measured posterior corneal curvature, were similar. To the best of our knowledge, the updated Barrett Toric Calculator is the first formula to provide non-inferior and reliable predictions based on measurement of posterior corneal curvature.

Blood pressure and glaucoma: At the crossroads between cardiology and ophthalmology.

Glaucoma is an optic nerve neuropathy of undetermined cause. Although many mechanisms are thought to be involved in the development and progression of the disease, only an increased intraocular pressure has been established as a clinically significant modifiable risk factor. Nevertheless, up to 40% of patients develop glaucoma without evidence of increased intraocular pressure. Ample evidence suggests that alterations in the control of arterial blood might negatively affect optic nerve function. However, evidence-based guidelines on the management of arterial blood pressure in glaucoma patients are lacking. Regrettably, intraocular pressure is generally not included as a secondary end-point in clinical trials on arterial hypertension. Considering the relative simplicity of intraocular pressure measurements and large number of patients included in hypertension studies, the benefits of including intraocular pressure as a secondary end-point could be of a great value for improving care for glaucoma patients. Therefore, closer collaboration between cardiologists and ophthalmologists is needed.

Variability of Dry Eye Disease Following Removal of Lacrimal Glands in Rats.

Removal of lacrimal glands is used as a viable model of dry eye disease in rats. However, there is no uniform agreement on the disease severity following different variants of the procedure. The interpretation of the modeled dry eye disease also is biased by the interchangeable use of male and female rats. Therefore, this study seeks to define the features of dry eye disease following removal of the extraorbital lacrimal gland, with or without excision of the infraorbital lacrimal gland in male and female rats. The experiments were performed in 12-week-old female and male Sprague-Dawley rats. The baseline blink rate and fluorescein score were assessed. Subsequently, rats underwent isolated removal of the extraorbital gland, removal of the extraorbital gland combined with excision of the infraorbital gland, or a sham surgical procedure. The assessment of blink rate and fluorescein scores was repeated 28 days following surgery. Corneas were collected for histological analysis. We found that the blink rate and fluorescein score increased in all of the experimental groups, except the control group and the male rats that underwent isolated removal of the extraorbital lacrimal gland. Histopathological analysis revealed the thinning and edema of the epithelium in all groups, except the control group. These changes were most pronounced in female rats following combined removal of extraorbital and infraorbital lacrimal glands. In conclusion, severity of dry eye disease in the rat model is influenced by both gender and the extent of surgical removal of lacrimal glands. Combined excision of lacrimal glands in female rats produced the most severe pathological changes, whereas isolated excision of the extraorbital lacrimal gland in male rats led to the least severe changes.

Effect of TMAO, a Gut-Bacteria Metabolite, on Dry Eye in a Rat Model.

PURPOSE Trimethylamine oxide (TMAO) is an osmolyte used by saltwater animals to protect their cells from hyperosmotic environment. Here, we studied if TMAO may exert beneficial effect in dry eye disease (DED) which results from hyperosmotic tear film. MATERIALS AND METHODS Female, 12-week-old Sprague-Dawley rats underwent either removal of extra- and infraorbital lacrimal glands (dry eye group) or sham surgery (sham group). A 1-week topical treatment with either 0.9% NaCl (control) or 1% TMAO in 0.9% NaCl solution was started 4 weeks after the surgery. Fluorescein score (FS), blink rate (BR), and histological picture of cornea were assessed. RESULTS At baseline, corneas did not stain with fluorescein and there was no difference between the groups in BR. There was a significant increase in FS and BR after the removal of lacrimal glands (p < 0.0001 and p = 0.0003, respectively). Accordingly, the dry eye group showed significantly higher FS and BR than the sham group (p = 0.0003 and p = 0.0005, respectively). Treatment with TMAO but not with 0.9% NaCl significantly reduced FS and BR (p = 0.01 and p = 0.005, respectively); however, FS and BR did not return to baseline (p = 0.0045 and p = 0.0065, respectively). In comparison to the control group, treatment with TMAO did not affect epithelial thickness or the number of layers of epithelium layers. CONCLUSIONS We have found that in a rat model of DED, the topical treatment with TMAO improves clinical picture, however does not lead to the evident histopathological recovery.

Patient-oriented mobile applications in ophthalmology.

BACKGROUND: Mobile solutions will improve patient care only if they are equally valued by physicians and their patients. Although mobile applications are gaining acceptance among ophthalmologists and optometrists, little is known about their adoption among patients. Therefore, this study was designed to analyse the market for patient-oriented mobile applications in ophthalmology. METHODS: Search engines of Google Play and App Store were utilised to find patient-oriented mobile applications. All applications were divided into seven subspecialties; dry eye, strabismus and amblyopia, macular degeneration, cataract, glaucoma, diabetic retinopathy and general ophthalmology. Subsequently, number of downloads, average patient rating, year of release and source of clinical information provided in the application were collected. Furthermore, in order to evaluate whether development of software responds to epidemiological demand, number of applications in each subspecialty was correlated with the prevalence of particular diseases. RESULTS: Fifty-six applications that met established criteria were found. The overall number of downloads was estimated at the level of 1.5 million, whereas the weighted average rating for all applications was 4.21/5. The number of applications by subspecialty did not correlate with the prevalence of particular eye disorder. The dry eye was the most frequently downloaded and best rated subspecialty. CONCLUSIONS: The overall number of patient-oriented applications in ophthalmology is low. Subspecialties are not equally equipped with patient-oriented mobile solutions. Furthermore, the number of applications or downloads in each subspecialty does not correlate with the number of potential users such as patients with particular eye disorders. Finally, ophthalmologists should encourage software developers to meet future demand for mobile solutions in eye disorders.

Butyrate, a Gut Bacterial Metabolite, Lowers Intraocular Pressure in Normotensive But Not in Hypertensive Rats.

BACKGROUND: Accumulating evidence supports a role of gut bacterial metabolites in arterial blood pressure (BP) regulation. Since the mechanisms controlling intraocular pressure (IOP) and BP overlap, we hypothesized that butyrate, a bacterial metabolite, might affect both IOP and BP. METHODS: IOP, BP, and heart rate (HR) were measured at baseline and after the intraperitoneal administration of either butyrate or a vehicle (0.9% NaCl) in anaesthetized normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). RESULTS: At baseline, there was no significant difference between WKY and SHR in IOP and HR, whereas BP was significantly higher in SHR. In WKY administration of butyrate produced a significant decrease in IOP and BP, which lasted throughout the experiment. IOP response to butyrate was similar between sham WKY and WKY, which had undergone unilateral superior cervical ganglion excision. In contrast, in SHR butyrate treatment did not affect IOP and produced only a transient decrease in BP. WKY showed no significant changes in HR whereas SHR exhibited an increase in HR. CONCLUSIONS: Butyrate, a gut bacterial metabolite, lowers IOP in normotensive but not in hypertensive rats. The effect is independent of ocular sympathetic innervation. Given that changes in BP followed a different pattern than changes in IOP it seems that butyrate lowers IOP independently of BP changes.

A common humoral background of intraocular and arterial blood pressure dysregulation.

BACKGROUND: It has been postulated that intraocular pressure, an important glaucoma risk factor, correlates positively with arterial blood pressure (blood pressure). However, results of experimental and clinical studies are often contradictory. It is hypothesized that, in some hypertensive patients, disturbances in intraocular pressure regulation may depend on biological effects of blood borne hormones underlying a particular type of hypertension, rather than on blood pressure level itself. REVIEW: This review compares the effects of hormones on blood pressure and intraocular pressure, in order to identify a hormonal profile of hypertensive patients with an increased risk of intraocular pressure surge. The PUBMED database was searched to identify pre-clinical and clinical studies investigating the role of angiotensin II, vasopressin, adrenaline, noradrenaline, prostaglandins, and gaseous transmitters in the regulation of blood pressure and intraocular pressure. RESULTS: Studies included in the review suggest that intraocular and blood pressures often follow a different pattern of response to the same hormone. For example, vasopressin increases blood pressure, but decreases intraocular pressure. In contrast, high level of nitric oxide decreases blood pressure, but increases intraocular pressure. CONCLUSIONS: Arterial hypertension is associated with altered levels of blood borne hormones. Contradicting results of studies on the relationship between arterial hypertension and intraocular pressure might be partially explained by diverse effects of hormones on arterial and intraocular pressures. Further studies are needed to evaluate if hormonal profiling may help to identify glaucoma-prone patients.

Physician Review Portals Do Not Favor Highly Cited US Ophthalmologists.

PURPOSE: Physician review portals are becoming increasingly popular among patients and often serve as a primary advisory tool during the search for a doctor. However, it has not been established whether these platforms favor leaders of the field; i.e., physicians with high academic rank. Here, we assessed online ratings of US ophthalmologists, selected for their outstanding scientific performance. METHODS: This cross-sectional, Internet-based study was performed in September 2016. First, we selected US ophthalmologists who published at least one manuscript or conference abstract that reached at least 100 citations from 2006 to 2016. Second, academic impact of preselected physicians, measured by overall number of citations or Hirsch index, was correlated with their ratings on two physician review portals: healthgrades.com and zocdoc.com. RESULTS: We selected 105 ophthalmologists who met established criteria. A total of 78 were rated on healthgrades.com, but only two were rated on zocdoc.com. The average rating on healthgrades.com was 4.2 +/-0.9, similar to the previously reported US mean for a physician (∼4). The rating did not correlate with the number of citations or with Hirsh index. CONCLUSIONS: Highly cited ophthalmologist are not rated proportionately to their scientific achievements. Their reviews are positive, but do not stand out in comparison to other physicians. Additionally, we found that this group of ophthalmologists might be significantly underrepresented on particular review websites.

The Upright Body Position Increases Translaminar Pressure Gradient in Normotensive and Hypertensive Rats.

AIM: Several lines of evidence suggest that the pathogenesis of glaucoma may depend on an increased translaminar pressure gradient (TPG), the difference between intraocular and intracranial pressure (ICP), rather than on intraocular pressure (IOP) itself. It has also been suggested that high blood pressure might correlate with the incidence of glaucoma; however, the data are contradictory. Here, we studied the effect of arterial blood pressure and changes in body position on TPG in rats. METHODS: Experiments were performed on anesthetized 15- to 16-week-old, male, spontaneously hypertensive rats (hypertensive rats, n = 10) and Wistar-Kyoto rats (normotensive rats, n = 10). Continuous recordings of intracranial and IOPs were performed before, during, and after changing the body position from horizontal to vertical. RESULTS: At baseline, hypertensive rats had a significantly higher arterial blood pressure than normotensive rats, while intraocular and intracerebroventricular pressures and TPG did not differ between the groups. Changing the body position from horizontal to vertical produced a significant decrease in ICP, a nonsignificant decrease in IOP, and a significant increase in the TPG. There was no significant difference between normotensive and hypertensive rats in the pattern of changes in intraocular and intracerebroventricular pressures and TPG. CONCLUSIONS: Change in the body position from horizontal to vertical, but not hypertension, causes a significant increase in TPG in rats. If further studies confirm that TPG plays a role in the etiology of glaucoma, a vertical position and changes in the body position might be considered as debilitating factors.

Renal denervation decreases blood pressure and renal tyrosine hydroxylase but does not augment the effect of hypotensive drugs.

The effect of renal denervation on the efficacy of antihypertensive drugs has not yet been elucidated. Twenty-week-old spontaneously hypertensive rats were treated with metoprolol, losartan, indapamide, or saline (controls) and assigned to renal denervation or a sham procedure. Acute hemodynamic measurements were performed ten days later. Series showing a significant interaction between renal denervation and the drugs were repeated with chronic telemetry measurements. In the saline series, denervated rats showed a significantly lower mean arterial blood pressure (blood pressure) than the sham-operated rats. In contrast, in the metoprolol series denervated rats showed a significantly higher blood pressure than sham rats. There were no differences in blood pressure between denervated and sham rats in the losartan and indapamide series. In chronic studies, a 4-week treatment with metoprolol caused a decrease in blood pressure. Renal denervation and sham denervation performed 10 days after the onset of metoprolol treatment did not affect blood pressure. Denervated rats showed markedly reduced renal nerve tyrosine hydroxylase levels. In conclusion, renal denervation decreases blood pressure in hypertensive rats. The hypotensive action of metoprolol, indapamide, and losartan is not augmented by renal denervation, suggesting the absence of synergy between renal denervation and the drugs investigated in this study.

Drug resistant hypertension ­ no simple way out.

Hypertension poses growing challenge for health policy-makers and doctors worldwide. Recently published results of Symplicity-III trial (HTN-3), the first blinded, randomized, multicenter study on the efficacy of renal denervation for the treatment of resistant hypertension did not show a significant reduction of BP in patients with resistant hypertension 6 months after renal-artery denervation, as compared with controls. In this paper we review clinical and experimental studies on renal denervation. In order to identify causes of inconsistent results in renal denervation studies we look at basic science support for renal denervation and at designs of clinical trials.

The effect of simvastatin and pravastatin on arterial blood pressure, baroreflex, vasoconstrictor, and hypertensive effects of angiotensin II in Sprague-Dawley rats.

Research suggests that statins affect the regulation of arterial blood pressure (BP), however, the mechanisms remain obscure. We maintained male, 12-week-old, Sprague-Dawley rats on tap water (controls) or water containing simvastatin or pravastatin for 4 weeks. Subsequently, we measured mean arterial blood pressure and heart rate at baseline and after intravenous infusion of either saline or angiotensin II (Ang II). Additionally, we tested baroreflex function and the effect of statins on vasoconstrictor response to Ang II on isolated femoral artery branches. Controls and simvastatin and pravastatin groups showed a significant increase in mean arterial BP and heart rate in response to Ang II. The increase was significantly smaller in the simvastatin group than in controls and in the pravastatin group. In contrast, when pretreated with hexamethonium, a ganglionic blocker, simvastatin and pravastatin groups showed a similar hypertensive response to Ang II, which was smaller than in controls. Likewise, the Ang II-induced vasoconstrictor response of femoral artery branches was comparable between simvastatin and pravastatin groups and smaller than in controls. We found no effect of statins on the baroreflex. This study shows that simvastatin and pravastatin differ in their effects on the Ang II-dependent mechanisms controlling BP.