Search

Background: A common type of strabismus known as concomitant exotropia (XT) occurs when mismatched eyes deviate outward and the angle of deviation is the same regardless of which eye is fixed. Among ophthalmologists, there is no agreement on non-surgical treatment options for XT. For those who suffer from strabismus, surgery is an option for correcting their visual axis and restoring their ability to see in both eyes simultaneously. Instead, then severing the muscle, muscle plication involves folding the muscle around itself and stitching it in place, essentially shortening and tightening the muscle. Muscle plication has been found to reduce the risk of anterior segment ischemia by protecting the anterior ciliary arteries. Objective: To hallmark the new guidelines options of concomitant exotropia management. Conclusion: Muscle-tightening techniques such as excision, plication, advancement, and transposition have been documented in the literature. Technical simplicity, the ability to reverse it, shorter operating times, reduced surgical trauma, and the preservation of anterior ciliary arteries are only a few of the many advantages of plication.

AIM: To quantitatively investigate the retinal vascular diameter changes, analyzing the early and long-term effects on the retinal circulation, with 6-month follow-up. METHODS: Patients underwent horizontal strabismus surgery were enrolled prospectively. Retinal vessel diameters on color fundus photographs were assessed before and 1, 7d, 6mo after surgery, using a computer-assisted quantitative assessment software. To evaluate the retinal vascular caliber changes, retinal vascular diameters were calculated by means of the Parr–Hubbard formula as the central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE). The arteriovenous ratio (AVR) was calculated as CRAE divided by CRVE. RESULTS: A total of 154 eyes of 104 consecutive patients were included. Compared with the data before surgery (121.55±24.67), the mean CRAE (131.18±28.29) significantly increased 1d after surgery (P=0.003), but went back to baseline level at 7d (118.89±30.35, P=0.15), and 6mo (123.22±15.32, P=0.60), so did the AVR (P

Purpose The objective of this article is to document a unique case of a primary hemangioma and review epibulbar vascular tumors of the conjunctiva and episclera. Methods A case report with detailed histopathologic, histochemical, and immunohistochemical studies coupled with a comprehensive review of the relevant literature with a tabulation of previously reported epibulbar vascular lesions was performed. Results A vascular tumor developed in a 46-year-old woman over 2-3 months that histopathologically was located in the superficial third of the normally avascular sclera and was composed of capillary caliber vessels. CD31 and CD34 positivity established the vascular nature of the lesion. Despite its adult onset, the tumor was also glut-1 positive, a vascular characteristic of childhood capillary hemangiomas that will ultimately involute. Smooth muscle actin was positive in the endothelial cells and associated pericytes. An ectatic muscular vessel identified in the midst of the lesion was interpreted as an anomalous intrascleral branch of an epibulbar anterior ciliary artery, where it perforated the sclera in the vicinity of the insertion of an extraocular rectus muscle. It was deduced to be the source of the capillary proliferation. A literature review failed to identify any previously reported epibulbar vascular tumor that originated primarily in the sclera or secondarily infiltrated this ocular tunic. Conclusion An adult primary capillary intrascleral neoplasm is described as the rarest of all epibulbar vascular tumors and in keeping with the exceptional status of the ocular endothelium was glut-1 positive. This lesion must be distinguished from an array of other common and esoteric epibulbar vascular conditions.

Introduction A lot of different techniques have been proposed in order to manage abduction limitation secondary to sixth nerve palsy; however, anterior segment ischemia remains a concern. The aim of this study was to evaluate the results of augmented vertical recti muscle transposition (VRT) with partial recession of medial rectus muscle (MR) for complete, chronic sixth nerve palsy, a new modified technique that could also minimize the risk for anterior segment ischemia (ASI). Methods In this nonrandomized 8-year (2009–2017) retrospective review, 20 patients with complete sixth nerve palsy and contracted MR were enrolled. All of them underwent augmented VRT and partial recession of the MR, following a new proposed surgical technique. Only the central part of the MR tendon and belly was recessed by 6.5 mm, leaving 1.5 mm of the upper pole and 1.5 mm of the lower pole of the muscle intact, preserving the circulation of two anterior ciliary arteries. Results Twenty patients with a mean age of 43 years (range 12–71), all unilateral cases, were enrolled in this study. The mean preoperative deviation was 64.25 ± 10.9 prism diopters (PD) base out (range 50 to 90). In 17 cases (88%), the postoperative deviation was within 10 PD of orthotropia. Two patients (10%) had residual esotropia (15 PD and 20 PD, respectively), and one patient (5%) had 10 PD of hypotropia. The mean preoperative abduction limitation of −5.9 improved to −3.1 (p

Haemoglobin Video Imaging (HVI) demonstrates conjunctival and episcleral blood flow in man with the resolution of a single erythrocyte. A new method for establishing vessel hierarchy in micro-circulations is described, which recognises either delivery or drainage vessels and references vessel order to the capillary. These tools have been used to characterise blood flow. Anterior ciliary arteries show pulsatile variation in diameter. The episcleral arterial circle that they supply has functional apices with pulsatile flow reversal. Perfusion fields overlap: a single delivery vessel may project to many drainage vessels and vice-versa. Some vascular pathways remained inactive throughout a 1 min angiogram. Small conjunctival delivery vessels have laminar flow, but advancing luminal constrictions are often observed within the blood column. Laminar flow is lost in low-order drainage vessels where erythrocytes aggregate, but quickly recovers, new striae being added to the blood column at each confluence. Aqueous forms a discrete column, which centralises in episcleral drainage vessels. There is strong evidence that the luminal constrictions in small delivery vessels propel blood by peristalsis: they form spontaneously, remote from bifurcations; a single vessel may have multiple constrictions; they truly narrow the lumen, rarely contributing volume to post-capillary venules; they can proceed faster than the vessel contents; they never enter the drainage system; the trailing edges of erythrocyte boluses usually taper. They are rhythmically aligned with cardiac systole. While blood is transported to the periphery by the heart, it is actively transferred through tissues by peristalsis in small delivery vessels.

Purpose To report the occurrence of an episcleral AVM and to discuss the gravity as well as management of dilated tortuous episcleral vasculature. Observation A 16-year-old Asian male presented with redness in the left eye since birth and a history of gradual painless progressive increase in size since the past two years, causing a cosmetic concern for the patient. There was no history of any diminution of vision, diplopia, headache, trauma or any similar lesions anywhere in the body. On examination, unaided visual acuity (UCVA) was 6/6 Snellen in both eyes. Hirschberg's reflex was central and extraocular movements were full and free in both the eyes. On slit-lamp examination, dilated tortuous episcleral vessels were found in the temporal aspect of the palpebral aperture, shaped like a single continuous vascular frond, vertically measuring 10–11mm in extent and horizontally commencing 6mm from the temporal limbus but the posterior limit could not be discernible. The episcleral plane was freely mobile from the overlying conjunctiva and underlying sclera. The dilated episcleral vasculature remained unchanged on Valsalava maneuver and on bending forward. Intraocular pressure was 14 mmHg by Goldmann's appalanation tonometer in both eyes. Iris was normal in configuration and gonioscopy revealed open angles without any evidence of any neovascularisation in both eyes. Fundus examination was unremarkable. USG B-scan was grossly normal. MR Angiography of head and orbit with using thin high-resolution cuts (1mm using 3T machine) was done and was later followed up with a Contrast Enhanced MRI. Both imaging studies revealed an isolated episcleral AVM with a possible feeder vessel from the anterior ciliary artery to the lateral rectus and without any intraorbital or intracranial lesion. A diagnosis of isolated episcleral AVM was made. The episcleral plane was dissected and dilated tortuous vessels were excised. After cautery, conjunctival autograft was obtained from the fellow-eye was used to cover the defect. Histopathological examination revealed both thick and thin walled vessels of varying calibre corresponding to arteries and veins confirming the diagnosis of isolated episcleral AVM. Ref. Fig. 2. No recurrence has been observed over a follow-up period of 1 year. Conclusion AND IMPORTANCE: Isolated idiopathic episcleral AVM should be a diagnosis of exclusion. A thorough systemic and ophthalmological evaluation including a glaucoma workup is necessary for both diagnosis and management. UBM and MRI/MRA may be required in select cases to rule out any associations or complications. Management includes observation, embolization and excision.

Summary Purpose During the surgical correction of dysthyroid diplopia, the risk of ischemia by transection of the anterior ciliary arteries is well-known. In order to avoid this, we modified the classical surgical technique: (1) through the preservation of the vascular pedicles during muscle recession and (2) if necessary, through a plication (instead of a resection) of the ipsilateral antagonist muscle. The objective to be achieved is thus the resolution of the diplopia without ischemic complications. Subjects and methods We report a prospective series of 10 patients with dysthyroid ophthalmopathy, causing strabismic diplopia, all operated on by the same surgeon (BR) after at least 12 months of euthyroidism. Data collection included: history of previous decompressive surgery, surgical procedure, and oculomotor status before and after surgery. Results Ten patients (8 females), aged 51 to 74 years (mean age, 58.00 ± 7.62 years), were collected between 2008 and 2012. All patients had one or more vascular risk factors (diabetes, smoking, obesity, high blood pressure). With a follow-up from 16 to 67 months (mean ± SD 27.7 months ± 14.87), surgical outcomes were excellent: diplopia was cured in all cases, with recovery of stereoscopic vision. We had no operative or postoperative complications. Conclusions The technique of preservation of the anterior ciliary vascularization, which is particularly justified for these fragile patients, is compatible with moderate muscle recessions. For larger deviations, in which a larger recession might increase the proptosis, it is possible to add a plication of the ipsilateral antagonist. This surgical technique made possible the suppression of the diplopia in all cases.

Blood vessels supplying ocular structures originate from the internal carotid artery, so the blood supply of the eyes and the brain are closely connected. The various branches of the ophthalmic artery (central retinal artery, short and long posterior ciliary arteries, lacrimal artery, anterior ciliary artery) originating from the internal carotid artery and the corresponding veins are responsible for supplying the region indicated by their name. In rare cases, when the ophthalmic artery is absent, the medial meningeal artery performs the same task. The uvea is supplied by the ciliary artery, and the retina gets its blood supply from the branches of the central retinal artery. The posterior ciliary arteries (that supply the optic disc) and the central retinal artery (that supplies the medial two-thirds of the retina) are the first arteries to branch off the ophthalmic artery that enters through the optic foramen. The central retinal artery divides into superior temporal, inferior temporal and nasal branches. The next vessels to branch off are the long posterior ciliary arteries that supply the peripheral parts of the choroidea, the ciliary body and the iris. The last branch is that of the anterior ciliary arteries. Venous drainage from the retina is carried out by the central retinal vein and its smaller branches that have the same name and course as the corresponding arteries. The vorticose veins drain the choroidea towards the inferior and superior ophthalmic vein and the cavernous sinus. The capillary network between the retinal arteries and veins serves to ensure overly efficient oxygen and nutrient exchange. It is only the macula lutea (responsible for acute vision) and the fovea centralis that have no capillaries. Another special feature of these vessels is that retinal blood vessels have the same structure as cervical ones, and it is also true for uveal and extracranial vessels. These veins and arteries are located very close to each other, sometimes in the same adventitia sheath.

Examination of 1029 subjects disclosed 30-60 micron-sized frog's egg-like lipid deposits subconjunctivally and episclerally in 34%. The prevalence was found to rise steadily with increasing age to a maximum between 70 and 80 (52%). The prevalence declined after the age of 80. Both sexes were equally represented, except in the age groups over 70, where females predominated. In 48% lipid deposits were presented in both eyes, located nasally, temporally, inferiorly, and superiorly in decreasing order of frequency. Vertical location alone was found in 13%. The number of lipid globules was the greatest horizontally (median value nasally 20, temporally 30) and the smallest vertically (median value inferiorly 8, superiorly 15). The lipid deposits were generally found in relation to anterior ciliary arteries, most frequently off the upper corner of the horizontal muscles. In no more than 13% were such deposits seen as pads bearing no relation to vessels, and in 1% between tendon fibres, likewise non-related to vessels. No relation was noticed to presence of pinguecula, pterygium, and scleral plaques, nor to blood pressure or particularly thick conjunctiva. Lipid deposits were rarer in cases with an extraordinarily thin conjunctiva. Presence of lipid deposits may possible be accountable for by injuries of the arterial wall due to eye muscle movements with subsequent exudation of lipids into the surrounding episcleral connective tissue.

To quantify the anterior ciliary arteries that accompany horizontal rectus muscles and to correlate these findings with analysis of arterial cross-sectional area in distal tendons of these muscles.In 31 consecutive patients, previously unoperated horizontal rectus muscles were photographed intraoperatively. Major and minor anterior ciliary arteries (ACAs) were counted from the photographs by a masked independent observer and compared between medial and lateral rectus muscles. Cross sections from medial and lateral rectus muscle resection specimens were stained for elastin to quantify arterial volume in the distal tendons.Twenty lateral and 22 medial rectus muscles from 31 patients were included. There was no significant difference in the mean number of major anterior ciliary arteries between lateral rectus muscles (2.25 +/- 0.79, range 1-4) and medial rectus muscles (2.05 +/- 0.65, range 1-3) (p = 0.46). The mean number of minor anterior ciliary arteries was 6.7 in both medial and lateral rectus muscles (p = 0.97). Resected rectus muscle tendons showed no significant difference between lateral and medial rectus muscles for arterial vessel number or cross-sectional area.These results show the contribution from the lateral rectus muscle to the anterior segment circulation may be more robust than is commonly taught.

The posterior ciliary arteries (PCAs) supply the choroid and the optic nerve head. As discussed in Chap. 4, information on the vascular pattern of the choroid and of the PCAs was previously drawn entirely from postmortem cast studies, ever since the first description by Frederik Ruysch [1] in 1700. Extensive anatomical studies of the choroidal vascular bed have been conducted, mostly by studying casts prepared by the postmortem injection of a variety of materials [2–8] and also by studying casts by scanning electron microscopy [9–12]. These studies formed the basis of the classical anatomical textbook description of the choroidal vasculature. According to most of these descriptions: (1) PCAs have no segmental distribution, (2) they anastomose freely with one another as well as with the anterior ciliary arteries, (3) there are inter-arterial and arteriovenous anastomoses in the choroid, and (4) the choriocapillaris forms a freely communicating and an uninterrupted vascular bed in the entire choroid [8, 11]. From these postmortem anatomical descriptions, it was generally concluded that occlusion of PCA or one of its branches should not produce an ischemic lesion.

Objective To measure changes in the ocular and orbital blood flow velocities by color Doppler imaging (CDI) in beagles with primary open angle glaucoma as the disease progressed from early to advanced stages. Methods CDI measurements were performed periodically on 13 glaucomatous Beagles during the nontreated mild, moderate and advanced stages of POAG over the course of 4 years. CDI was performed with the dogs lightly anesthetized (butorphanol 0.1 mg/kg IV, acepromazine maleate 0.02 mg/kg IV, and atropine sulfate 0.05 mg/kg) while the CD transducer was placed directly on the cornea anesthetized with 0.5% tetracaine hydrochloride. Intraocular pressure (IOP) by pneumatonography or TonoPen XL, heart rate and mean arterial blood pressure were measured at the beginning, middle and end of each study. The ophthalmic vessels examined included: external ophthalmic arteries and veins, long and short posterior ciliary arteries, anterior ciliary arteries and veins, primary retinal arteries, and vortex veins. Recordings of each vessel included peak systolic velocity (PSV), end diastolic velocity (EDV) and time averaged velocity (TAV), and when possible the resistive index (RI) and pulsatility index (PI) were computed. Results CDI abnormalities were present before intraocular pressure exceeded the normal range. As the animals aged, and the glaucoma progressed with higher levels of IOP, significant changes occurred in nearly all vessels, and generally included a major increase in RI (P

BACKGROUND To investigate the vasoactive effect of bimatoprost (Lumigan), a new topical ocular hypotensive agent, in isolated porcine ciliary arteries. MATERIAL AND METHODS Arteries were placed in a myograph system to measure isometric forces. Quiescent vessels as well as vessels pre-contracted with either 10 nM endothelin-1 or 100 mM potassium chloride (KCl) were exposed, in a cumulative manner, to increasing concentrations (0.1 nM - 0.1 mM) of bimatoprost (dissolved in ethanol). In quiescent vessels, results were expressed in percent of 100 mM KCl-induced contraction. In endothelin-1-pre-contracted vessels, results were expressed in percent of the maximal contraction induced by endothelin-1. In KCl-pre-contracted vessels, results were expressed in percent of the plateau contraction reached 30 minutes after 100 mM KCl application. RESULTS Bimatoprost induced a significant (p < 0.05 - 0.001) vasoconstriction at concentrations equal to or higher than 0.1 micro M in quiescent vessels (0.1 mM: 73 +/- 12 %). In KCl-pre-contracted vessels, at concentrations higher than 1 micro M, bimatoprost induced significant (p < 0.05 - 0.01) contractions (0.1 mM: 67 +/- 17 %). In endothelin-1-pre-contracted vessels, bimatoprost also induced significant (p < 0.05 - 0.001) contractions at concentrations above 10 micro M (0.1 mM: 17 +/- 8 %). CONCLUSIONS The present study indicates that bimatoprost appears to have, in vitro, some vasoactive properties in porcine ciliary arteries. The question whether Lumigan has an influence on ocular blood flow needs to be further investigated.

Background: Anterior ciliary arteries travelling along recti muscles provide anterior segment vascularization, which can be compromised by surgery involving more than 2 muscles. Patients and Methods: We studied retrospectively the files of 10 patients in whom a fluorescein angiography of the iris had been performed as a pre-operative assessment prior to a second or third oculomotor surgery. Results: The median age of the patients was 47.5 years (range 15 to 73 years). Relative iris ischemia was present in 4 patients following multiple surgeries, none of them presenting any general cardiovascular risk. The initial surgical protocol was modified according to angiographic results in these 4 patients. Conclusion: When further surgery has to be performed on previously multi-operated patients, anterior segment angiography can be useful in the planning of surgery in order to minimize the risks of anterior segment ischemia.

BACKGROUND: To investigate whether dilutions of the commercially available Xalatan(R) or Cosopt(R) induce vasoconstrictions in isolated quiescent porcine ciliary arteries. MATERIAL AND METHODS: Contractions measured with a myograph system (isometric force measurement) were expressed in percent of 100 mM potassium chloride(KCl)-induced contraction (mean +/- standard error). In preliminary experiments, vessels were contracted with 100 mM KCl after previous exposures to different dilutions of Xalatan(R) (1/250 to 1/50) or Cosopt(R) (1/500 to 1/5). In a further series of experiments, vessels were exposed in a cumulative manner to different dilutions of Xalatan(R) or Cosopt(R) (1/50 000 to 1/166). RESULTS: Contractions induced by 100 mM KCl were not significantly affected by previous exposure to Xalatan(R) or Cosopt(R) at dilutions higher than 1/166 and 1/50, respectively. However, at the lower dilutions tested, 100 mM KCl-induced contractions were significantly (p < 0.001) and markedly inhibited (1/50 Xalatan(R): 22.1 +/- 2.8 %; 1/5 Cosopt(R): 24.8 +/- 4.6 %). In quiescent vessels, diluted (1/50 000 to 1/166) preparations of Xalatan(R) induced, in a dilution-dependent manner, statistically significant (p < 0.05) but, however very small (3.2 +/- 1.0 %) contractions in comparison to Cosopt(R) (- 0.6 +/- 0.2 %). CONCLUSIONS: Although on the basis of these in vitro experiments no clinical interpretation should be made, at very high dilutions that did not affect KCl-induced contractions, Xalatan(R), but not Cosopt(R), had a very small vasoconstrictive effect in isolated quiescent porcine ciliary arteries. At low dilutions, responses to KCl were inhibited, possibly in relation to an unclear effect of the excipients of Xalatan(R) and Cosopt(R).

Importance Extraocular muscle strengthening is a common treatment for strabismus. Plication is an alternative procedure for strengthening muscles with less tissue trauma than resection. Objective To compare the surgical dose effect of plication with that of resection. Design, Setting, and Participants Retrospective comparison of surgical outcomes in an academic pediatric ophthalmology and strabismus practice from July 25, 2005, through March 28, 2013, with a mean follow-up of 137 days for plication and 1243 days for resection. A single surgeon performed all procedures. Twenty-two consecutive patients underwent bilateral horizontal rectus plication or plication combined with antagonist recession (13 with esotropia and 9 with exotropia; mean [SD] age, 38 [21] years). Thirty-one consecutive patients underwent bilateral resection or resection combined with antagonist recession (12 with esotropia and 19 with exotropia; mean [SD] age, 28 [24] years). Six patients underwent vertical rectus plication. Exposures Rectus resection or plication performed by folding the anterior tendon posteriorly under the muscle margins oversewn to the poles of the scleral insertion, avoiding the anterior ciliary arteries. Main Outcomes and Measures Postoperative binocular alignment at the first postoperative and last available examinations. Results Lateral rectus plication (mean [SD], 6.5 [2.2] mm) and resection (6.6 [1.6] mm) were performed for similar magnitudes of esotropia (27.9 [13.4] prism diopters [PD] for plication, 29.0 [15.2] PD for resection; P = .44). Mean (SD) initial correction by lateral rectus plication was 5.17 (0.29) PD/mm, slightly less than the 95% CI (5.51-7.75 PD/mm) for resection (6.63 [0.50] PD/mm). Medial rectus plication (mean [SD], 4.9 [0.9] mm) vs resection (5.1 [1.1] mm) was performed for similar magnitudes of exotropia (32.8 [14.2] PD for plication, 31.2 [15.6] PD for resection; P = .33). Mean (SD) initial correction by medial rectus plication (7.10 [1.65] PD/mm) was within the 95% CI (4.65-9.87 PD/mm) for resection (7.26 [1.23] PD/mm). Initial and late effects were similar. Ciliary circulation observed at surgery remained patent after plication. Plication was cosmetically acceptable and did not produce conspicuous tissue elevations. Conclusions and Relevance Horizontal rectus muscle plication is a rapidly performed, technically simple surgical procedure to strengthen the rectus muscles, with an equivalent (per millimeter) in surgical effect to that of medial rectus resection for treatment of esotropia and exotropia. Plication diminishes surgical trauma and does not intentionally sacrifice ciliary circulation, with the potential for reversal by suture release in the first postoperative days.

Purpose: To investigate contractions evoked by the thromboxane A 2 analog U 46619 and by the inhibitor of nitric oxide formation N G -nitro-L-arginine methyl ester (L-NAME) in isolated porcine ciliary arteries and vortex veins. Material and Methods: In a myograph system (for isometric forces measurement), vessels were exposed (at different levels of wall tension) to 100 mM potassium chloride (KCI). At their optimal tension, vessels were exposed (in a cumulative manner) to increasing concentrations of U 46619 (0.1 nM - 1 μM) in the absence or in the presence of L-NAME (0.1 mM). Contractions were expressed in mN or in percent of a 100 mM KCI-induced contraction. Results: Optimal tension was higher in arteries (7 mN) than in veins (3 mN). Maximal contractions induced by KCI were stronger in arteries (24.4 ± 3.6 mN; n=8) than in veins (1.8 ± 0.2 mN; n = 8). In contrast, maximal contractions evoked by U 46619 were proportionally higher (p < 0.001) in veins (178.3 ± 8.9%; n=8) than in arteries (108.4 ± 2.6%; n=5) and were not significantly affected by L-NAME. Sensitivity to U 46619 was not significantly different between arteries (pD 50 = 7.7 ± 0.1) and veins (pD 50 = 7.9 ± 0.1). In quiescent vessels, L-NAME evoked contractions that were higher (p < 0.001) in veins (43 ± 7.9%; n = 13) than in arteries (7.5 ± 1.7 %; n = 10). Conclusions: When compared with KCI-induced contractions, contractions evoked by U 46619 or L-NAME are proportionally higher in porcine vortex veins than in ciliary arteries.

The objective of this study was to compare orbital and ocular vasculature velocity, measured by Doppler imaging, in normal Beagles and Beagles with inherited primary open-angle glaucoma. Eight normal Beagles and 13 Beagles with different stages of primary open-angle glaucoma were evaluated twice with a 2-4-week period between measurements. Doppler imaging was performed with the dogs anesthetized, and the Doppler transducer applied directly on the corneal surface. The majority of the orbital vasculature (external ethmoidal artery; internal ophthalmic artery and vein; and external ophthalmic artery and vein) and ocular blood vessels (anterior ciliary artery and veins; long posterior ciliary arteries; short posterior ciliary arteries; primary retinal arteries; and the vortex veins) were identified and Doppler blood velocity parameters were determined. The glaucomatous dogs demonstrated significant differences in the Doppler velocity parameters of several orbital vessels (external ethmoidal, external ophthalmic, and internal ophthalmic arteries), and several ocular vessels (anterior ciliary, short posterior ciliary, and long posterior ciliary arteries). These differences included decreased blood velocities, and increased pulsatility and resistive indexes. The Doppler blood flow velocities of the primary retinal arteries were unchanged between the normal and glaucomatous dogs. In the glaucomatous dogs, the Doppler imaging suggests increased vascular resistance downstream in both the orbital and ocular vasculature. These blood velocity parameter changes may be primary or secondary, and may offer therapeutic opportunities to increase perfusion, prolong the retina and optic nerve head function, and maintain vision in the canine glaucomas.

BACKGROUND/AIMS—Endothelium dependent vasodilatation is an important regulator of blood flow to the eye but its role has not been investigated in vessels supplying the ciliary body. This study assessed the role of the endothelium in modulating vasoconstrictor responses of the intraocular bovine anterior ciliary artery. METHODS—Bovine anterior ciliary arteries (n=33) were mounted in a myograph, containing physiological salt solution at 37°C, for isometric force measurement. Cumulative concentration-response curves were obtained to the constrictor agonists 5-hydroxytryptamine (5-HT), noradrenaline, phenylephrine, prostaglandin F2α, endothelin-1, and KCl in both endothelium intact and denuded arteries. RESULTS—All vasoconstrictors produced sustained contractile responses which were unaffected by the removal of the endothelium. Responses to 5-HT were also unaffected by inhibition of nitric oxide synthase. CONCLUSION—These results indicate that neither agonist stimulated nor basal release of nitric oxide from the endothelium modulates responses to vasoconstrictor agonists in the isolated bovine anterior ciliary artery when measured in a no flow isometric system. Keywords: anterior ciliary artery; constrictor agonists; endothelium; nitric oxide

• Background: The microvascular changes secondary to anterior segment ischemia following tenotomy of the extraocular muscles have not been studied in the rabbit. • Methods: Using scanning electron microscopy of methylmethacrylate ocular microvascular luminal castings, the anterior eye segment vasculature after tenotomy was documented and compared to that after occlusion of the bilateral long posterior ciliary arteries and that in the eyes that were not subjected to any surgical intervention. • Results: Five days and 1 week after the surgical intervention with tenotomy, microvascular change secondary to the anterior segment ischemia was not apparent, but 2 weeks after the tenotomy subtle evidence of ischemia such as new vessels in the iris was observed. Seven weeks after tenotomy, marked microvascular change was observed where corneal new vessels arose from the superior perilimbal arteries. In contrast, we found prominent microvascular changes 2 weeks after the occlusion of the long posterior ciliary arteries. • Conclusions: Tenotomy of the rabbit eye causes microvascular change similar to that in occlusion of the long posterior ciliary arteries. This result suggests that the anterior ciliary artery of the rabbit contributes blood flow to the anterior eye segment and also has a stronger connection with the long posterior ciliary artery than previously reported.

Purpose To determine normal values of bloodflow velocities in extraocular vessels. Methods In one eye each in 189 healthy adult volunteers, blood-flow velocities in the ophthalmic artery (OA), central retinal artery (CRA), central retinal vein (CRV), short lateral posterior ciliary artery (LPCA), and short medial posterior ciliary artery (MPCA) were measured by color Doppler imaging. In the arteries, peak systolic velocity (PSV), end diastolic velocity (EDV), and resistivity index (RI) were calculated. In the CRV, maximal and minimal blood-flow velocities were measured. Influence of age, gender, blood pressure, and heart rate on blood-flow velocities and the resistivity index were analyzed. Results Mean outcomes ± S.D. cm/sec were as follows: in the OA, PSV was 39.2 ± 5.3, EDV was 9.1 ± 2.5, and RI was 0.77 ± 0.05. In the CRA, PSV was 11.0 ± 1.8, EDV was 3.3 ± 0.9, and RI was 0.71 ± 0.05. In the short LPCA, PSV was 11.2 ± 1.7, EDV was 3.7 ± 1.0, and RI was 0.68 ± 0.06. In the short MPCA, PSV was 11.2 ± 11.7, EDV was 3.6 ± 0.9, and RI was 0.68 ± 0.05. In the CRV, mean maximal velocity was 4.5 ± 0.9, and mean minimal velocity was 3.3 ± 0.7. Age, gender, systolic blood pressure, diastolic blood pressure, and heart rate had no consistent statistically significant influence on the measured and calculated variables. Conclusion Normal values for blood-flow velocities in the extraocular vessels serve as a basis in deciding whether a measured value of a patient is normal or abnormal.

Orbital and intrabulbar arteries were studied in 20 equine eyes by means of latex injections and methylmethacrylate casts. The orbital branches of the external ophthalmic artery arise far caudal to the posterior pole of the eyeball and present a variable topographic arrangement. The intrabulbar arteries are supplied by ciliary and choroidoretinal arteries. Dependent on their entrance into the eyeball, the ciliary arteries are subdivided into a posterior and an anterior group. The posterior ciliary arteries perforate the sclera post equatorially and consist of 4 major vessels that penetrate in the lateral, medial, dorsal and ventral meridian of the eyeball, respectively. The lateral and medial of these arteries follow a long intrabulbar trajectory after having supplied several short posterior ciliary arteries to the choroid. The anterior ciliary arteries consist of a dorsal and a ventral vessel which penetrate the eyeball in the pericorneal area. The choroidoretinal arteries form an arterial network around the optic nerve at the posterior pole of the eyeball. They give rise to all retinal arterioles and some peridiscal choroidal branches. The larger part of the choroid is supplied by branches of the posterior ciliary arteries. Additionally, the anterior choroid receives recurrent branches from an arterial circle that lies externally in the ciliary ring. The iris contains a major arterial circle formed by the lateral and medial long posterior ciliary arteries and both anterior ciliary arteries. A minor iridic arterial circle nor central retinal artery could be found in the equine eyes examined.

Purpose: To evaluate the angioarchitecture and the hemodynamics in the peripheral choroid in humans. Methods: Choroidal circulation was examined in 23 normal eyes and in 7 with equatorial lattice degeneration by wide-angle indocyanine green (ICG) angiography using a scanning laser ophthalmoscope. A hand-held 30-diopter lens was placed in front of the eye to expand the observation angle from the original 40° to 70°. The peripheral temporal Choroid and ora serrata thus could be seen in one frame. Results: An arterial watershed zone was identified in the temporal peripheral choroid in 21 of 30 eyes. This watershed zone was located in a sectorial region posterior to the ora serrata. It did not form a circular belt along the equator. The area anterior to the watershed zone was supplied by peripheral retrograde choroidal arteries. Inflow of dye into the peripheral retrograde choroidal arteries was consistently later than into the more posterior choroid via short posterior ciliary arteries. The terminal branches of peripheral and short posterior ciliary arteries did not form functional anastomoses. Peripheral retrograde choroidal arteries showed wide variations in number and distribution. These arteries originated from recurrent branches of long posterior ciliary arteries in 18 of 21 eyes and from anterior ciliary arteries in 3 eyes. There was no correlation between the watershed zone and equatorial lattice degeneration in location and extent. Conclusion: A peripheral watershed zone is a regular feature in the far temporal sector of the choroid. The far peripheral choroid anterior to the watershed zone was perfused by peripheral retrograde choroidal arteries which originated from the long posterior ciliary arteries and/or the anterior ciliary arteries.

The scanning angiographic microscope (SAM) provides a solution to the considerable technical difficulties associated with conventional episcleral fluorescein angiography. Standardised anterior segment fluorescein videoangiograms were performed using the SAM in each episcleral quadrant of the right eye in 6 normal subjects; frame-by-frame analysis proved important. Centripetal flow was seen in all 37 scleral perforating arteries investigated. Other features were the marked individual variability, much larger vertical anterior ciliary arteries, the high frequency of arteriovenous anastomoses, the complex flow patterns, the absence of a 'watershed' zone between anterior ciliary and posterior episcleral circulations, a characteristic and discontinuous distribution of 'leaky' episcleral veins, and the primacy of venous drainage into the plexus of muscular veins. Reports of retrograde blood flow in the anterior ciliary arteries in most fluorescein angiographic studies are probably incorrect, the result of unappreciated methodological problems. The SAM is an important advance on previous anterior segment fluorescein angiography techniques.

Purpose: The purpose of this study was to assess the vasoconstrictor effect of the prostaglandin F 2α analog latanoprost in isolated porcine ciliary arteries. Material and Methods: With a myograph system to measure isometric forces, porcine ciliary arteries were exposed, in a cumulative manner, to increasing concentrations of latanoprost (0.1 nM - 0.1 mM). Experiments were conducted in quiescent vessels as well as in vessels precontracted with potassium chloride (KCl; 40 mM) or endothelin-1 (10 nM). Contractions were expressed in percent of 100 mM KCI-induced contraction. Results: In a concentration dependent manner latanoprost induced significant (p < 0.001) contractions in quiescent vessels (maximum: 68 ± 3%, n = 5; PD 50 : 5.7 ± 0.1). In KCl or in endothelin-1 precontracted vessels latanoprost did not evoke any relaxation but in contrast significant (p < 0.001) contractions (maximum: 33 ± 4%, n = 5 and 26 ± 6%, n = 8, respectively). Conclusions: Latanoprost has a vasoconstrictor effect in isolated porcine ciliary arteries. No relaxation could be observed. The clinical relevance of this finding requires further evaluation.

The ciliary body (CB) is supplied with blood from the anterior ciliary arteries (which arise from the four recti muscle arteries) and the long posterior ciliary arteries which traverse the interior. A complex arrangement of branches and anastomoses from these cells culminates circularly arranged vessels, including the episcleral arterial circle, the intramuscular circle of the ciliary muscle, and the major arterial circle (MAC). Each ciliary process receives blood from branches off the MAC, which follow a tortuous route through three vascular territories. Venules drain through the pars plana and exit via the vortex veins. CB vessels have wide lumens and are fenestrated, allowing production of aqueous humor. The complexity, density, and redundancy of vessels ensures consistent perfusion of the anterior segment.

A micropuncture technique was used to measure the pressure in the anterior ciliary arteries of monkeys as well as the pressures in the choroidal veins and in the choriocapillaris of rabbits. Monkeys were used to measure the pressure in one of the anterior ciliary arteries at three different points, First at a scleral 'well', and then at 2 and 5 mm from the same 'well'. It was found that the pressures recorded increased proportionally to the distance from the scleral 'well'. Afterwards the intraocular pressure (IOP) was increased stepwise and the arterial pressure was measured at each increment (from spontaneous IOP to 50 cmH2O). When compared, it was found that an increase in IOP was not followed by a statistically increased anterior ciliary artery pressure. The pressure in the choroidal veins and the choriocapillaris was measured in rabbits through a scleral window positioned between the two superior veins at about 4 mm from the nearest. The pressure recorded in the choroidal vein was found to be 3.3 +/- 0.4 cmH2O higher than the spontaneous IOP (20.3 +/- 1.6). However, when the IOP was increased stepwise it was found that this difference diminished as the value for the IOP neared the arterial pressure. Thus, the pressure gradient for flow from the intermediate-seized choroidal veins to the intraocular origin of the vortex veins is only a few cmH2O under normal conditions and is reduced at very high intraocular pressures at which the blood flow is markedly reduced or stopped.(ABSTRACT TRUNCATED AT 250 WORDS)

Removal of a rectus muscle results in permanent interruption of blood flow in the corresponding anterior ciliary artery, predisposing to anterior segment ischemia (ASI). A subhuman primate model of ASI was developed in order to study a novel muscle tuck procedure designed to preserve anterior ciliary artery circulation. Fluorescein angiograms were obtained before and after surgery to determine the effect of the muscle surgery on iris circulation. A total of 12 eyes from 12 cynomolgus monkeys underwent strabismus surgery consisting of tenectomy of all 4 rectus muscles in 3 eyes, tenectomy of 3 rectus muscles in 3 eyes, and tenectomy of 3 rectus muscles and muscle to sclera tuck of the remaining recti in 6 eyes. Postoperative angiograms documented preservation of perfusion in the distribution of the tucked muscle in all cases except one, in which there was iatrogenic trauma and disruption of anterior ciliary arteries. The modified tuck procedure thus appears to preserve anterior ciliary artery blood flow, and may be useful as a muscle strengthening procedure in patients predisposed to developing ASI.

The microvasculature of the eye of 10 pigs was investigated using scanning electron micrographs of corrosion casts. The ciliary body, iris and bulbar conjunctiva were supplied by the iridociliary ring artery via the long posterior ciliary artery. Capillaries of the ciliary process were of large diameter (23.2-27.5 microm) with an irregular bore, forming a thoroughfare channel draining blood in the ciliary arterioles into the pars plana venous vessels. Arterioles and venules in the iris exhibited a zigzag or spiral features. The third palpebra was supplied by the anterior ciliary artery. The capillary bed of the third palpebra was dense and was formed by many rows of fine hair-pin loops. Capillaries in the bulbar conjunctiva formed a sparse network disposing approximately parallel to the epithelium and formed a well-developed venous plexus, draining into the vortex veins. Retinal arterioles formed a slender and long course to capillaries. Retinal capillaries were extremely thin (3.0-4.0 microm in diameter). The choroid was supplied by the short posterior ciliary arteries. Choroidal arterioles exhibited a thick and short course to the choriocapillaris. The choriocapillaris was flat and sinusoid-like (8.9-13.9 microm in diameter), forming a dense sheet-like network. Blood from the choroid emptied into the episcleral vein via the vortex vein. Blood from the retina was drained by the posterior ciliary veins. The functional significance of this vascular architecture was discussed.

Case report: A 69-year-old male presented with bilateral blurred vision, left periocular pain, and headache. Ocular examination revealed a right optic neuropathy and left anterior segment ischaemia. An elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) raised suspicion of giant cell arteritis (GCA), which was confirmed by temporal artery biopsy. Treatment with intravenous methylprednisolone followed by a gradually reducing dose of oral prednisolone improved vision in both eyes. Comments: GCA typically affects large- and medium-sized vessels. It is a recognised cause of anterior ischaemic optic neuropathy. Anterior segment ischaemia is usually caused by disease of the anterior ciliary arteries not typically affected by GCA. This case illustrates that GCA can rarely cause anterior segment ischaemia, without posterior segment involvement in the same eye.

PURPOSE We investigated hemodynamic changes in the ophthalmic artery (OA) using color Doppler imaging (CDI) after two horizontal rectus muscles surgery. METHODS Eyes of the surgical group (n=18) underwent surgery on two horizontal rectus muscles, and the control group was the contralateral eyes. CDI of the OA was performed before operation and on postoperative days (POD) 1, 7 and 30. Peak systolic (Vmax), end diastolic (Vmin), and mean (Vmean) blood flow velocities were measured, and resistivity index (RI) and pulsatility index (PI) were calculated. RESULTS Vmax, Vmin and Vmean were significantly higher, and RI and PI were significantly lower in the surgical group than in the control group on POD 1 (p

Publisher Summary This chapter discusses the choroidal circulation and the circulation of the optic disc. In humans, the choroidal circulation is derived from the ophthalmic artery that branches into the central retinal artery and the main posterior ciliary arteries and several anterior ciliary arteries. One to five main posterior ciliary arteries usually supply the choroid. These main posterior ciliary arteries run anteriorly along the optic nerve. Blood flow to the optic disc is obtained from three sources, classically described as supplying three distinct layers of optic nerve head tissue. The immediate retrobulbar part of the optic nerve is supplied from the central retinal artery. The chapter also discusses the innervation of the choroid and the choroidal blood flow measurements. Direct clinical measurement of choroidal blood is currently not feasible. Only indirect methods are available. These include Doppler measurements of velocity of blood flow either by ultrasound in the ciliary arteries or diode‐laser light in the submacular choroidal vasculature.

To investigate the effect of aging on vasodilation of arterioles induced by prostaglandin E1 incorporated in lipid microspheres (lipo-PGE(1)), we measured the diameter of the anterior ciliary artery in patients aged65 years (young group) and in patients aged65 years (elderly group). An eyelid retractor was affixed to the right eyelid while patients were under general anesthesia, and changes in the diameter of the arteriole were continuously monitored by surgical stereomicroscopy for 10 min after the intravenous (i.v.) injection of lipo-PGE(1) (0.2 mu g/kg). We also measured mean arterial pressure (MAP) and heart rate (HR) during the study. The diameter of the arteriole in the young group began to increase significantly 1 min after the injection (p0.01), reaching the maximal increase (42.3 +/- 7.4% above the preinjection level) at 3 min after continuous dilatation at the end of the study. In the elderly group, the diameter began to increase 2 min after the injection (p0.01), reached the maximal value (33.2 +/- 12.7% above the preinjection level) at 5 min, and then gradually decreased to the baseline value. MAP decreased continuously after the injection in both groups; there was no significant difference between the groups. HR in the young group began to increase after the injection and then returned to the baseline level, but in the elderly group it showed continuous increase throughout the study. These results suggest that aging impaired the vasodilatory response to lipo-PGE(1) in the anterior ciliary artery.

Background: Latanoprost is a prostaglandin (PG)F2 α analogue widely recognized in the treatment of glaucoma. To investigate the action of this drug on the ocular circulation, we have studied its effects on isolated rabbit ciliary artery. The data obtained on this drug are compared with the data from PGE2 and PGF2 α. Methods: Under the microscope, ciliary artery specimens were prepared from rabbit eyes and mounted in a myograph system. The effects of latanoprost, PGE2, and PGF2 α on the isolated rabbit ciliary artery were investigated in vitro using isometric tension recording methods. Results: Exogenously applied PGF2 α, but not latanoprost, evoked contraction in the rabbit ciliary artery. After precontraction with excess-[K]0 solution, latanoprost evoked relaxation dose-dependently. Latanoprost at a concentration of 100µM induced maximum relaxation, which was not blocked by 10 µM L-nitro-L-arginine methylester (L-NAME), 1 µM 8-37 calcitonin gene-related peptide (CGRP) or 10 µM indomethacin. Moreover, latanoprost induced relaxation even in preparations without endothelium. The maximum relaxation obtained with PGE2 was somewhat less than 50% of that with latanoprost. Conclusions: These results indicate that latanoprost and PGE2 relaxed rabbit ciliary artery to different degrees. The relaxation provoked by latanoprost was not dependent on endothelium and was not caused by intrinsic PG, CGRP or nitric oxide. The mechanism of this relaxation is not yet clear.

Purpose: The aim of this study was to investigate the vasorelaxing properties of pinacidil (a potassium-channel-opener) in isolated porcine ciliary arteries. Methods: Isometric contractions of isolated porcine ciliary arteries were measured with a myograph system. The vessels were first precontracted with the thromboxane A 2 analog U 46619 (0.1 μM), and then exposed, in a cumulative manner, to increasing concentrations of pinacidil (1 nM - 100 μM). Relaxations have been expressed in percent of the maximal contraction evoked by U 46619 (0.1 μM). Results: Pinacidil showed a pronounced concentration-dependent relaxing effect in isolated porcine ciliary arteries. The difference between pinacidil and time-control experiments was significant (100 μM: 112±2% vs. 18±6%, P < 0.0001). The half-maximal concentration (pD 50 ) value was 5.3 ± 0.1 (- log M). Conclusions: The present study indicates that pinacidil has marked vasorelaxing properties in isolated porcine ciliary arteries.

The architecture of the retina, choroid and anterior eye segment was investigated in 12 Syrian hamsters using scanning electron micrographs of methylmethacrylate corrosion casts. The hamster eye receives its primary blood supply from the long posterior ciliary artery, which directly enters the optic nerve head, and divides into three branches: the central retinal artery and medial and lateral long posterior ciliary arteries. In the retina the central retinal artery divides into six radiating branches. Retinal arterioles form a slender and long course to capillaries. Retinal capillaries are extremely thin in diameter and form a sparse capillary network. The choroid is supplied by the long posterior ciliary arteries. Choroidal arterioles exhibit a thick and short course to the choriocapillaris. The choriocapillaris is thick and sinusoid-like, forming a dense network in the choroid. The ciliary body, iris and bulbar conjunctiva are supplied by the anterior ciliary arteries, which are branches of the long posterior ciliary arteries. Capillaries supplying the anterior margin of the ciliary process are large in diameter with an irregular bore, forming a thoroughfare channel draining blood in the ciliary arterioles into the pars plana vessels. Blood from the retina is drained by the central retinal veins. Venules from the anterior eye segment empty into the vortex veins via the pars plana vessels. Venous blood from the choroid is drained only by vortex veins via the choroidal veins. The functional significance of the vascular architecture and species differences are discussed.

The purpose of this study was to assess the feasibility and reproducibility of color Doppler imaging (CDI) of the vasculature of the normal canine orbit and eye. Eight normal Beagles were evaluated by Doppler imaging. The goals of the study were to determine the location, spectral waveform morphology, specific blood velocity parameters, and reproducibility for the ophthalmic and orbital vessels most frequently identified in the normal dog. Vessels identified a majority of the time (> 50%) included: external ophthalmic artery, dorsal external ophthalmic vein, ventral external ophthalmic vein, internal ophthalmic artery, anterior ciliary artery and vein, short and long posterior ciliary arteries, primary retinal arteries, and vortex veins. Other vessels imaged less frequently included: external ethmoidal artery (50%), and primary retinal veins (25%). For each blood vessel the time averaged velocity, peak systolic velocity, minimum diastolic velocity, pulsatility index, and resistive index were determined. The ophthalmic and orbital vessels have unique spectral waveforms and velocities which serve as a basis for identification. Reproducibility of the most commonly imaged vessels of the canine eye and orbit with Doppler imaging was high (< 10% variation). Doppler imaging has the potential for determining noninvasively and consecutively the blood velocity parameters found in orbital and ocular diseases, including orbital inflammations and neoplasms; intraocular inflammations and neoplasms; vascular diseases including systemic vascular disease (hypertension), vasculopathies, and anemia; the glaucomas; and documentable follow-up after medical and/or surgical treatment of these diseases.

Anterior segment imaging using fluorescein angiography is only suitable in lightly pigmented irides as the brown pigmentation of the iris masks fluorescein transmission. Indocyanine green (ICG) angiography has excellent penetration of pigment epithelium and, therefore, has potential application in detecting perfusion changes of dark irides after strabismus surgery.A prospective study was conducted on patients older than 15 years undergoing strabismus surgery. A fundus camera was focused on the arteriolar tufts of the pupillary margin and 50 mg of ICG (concentration of 12.5 mg/ml) was given intravenously. Images were then obtained at 1 minute intervals of 5 minutes' duration.45 patients with a mean age of 54.6 years and a mean follow up period of 8.6 weeks were studied. There were 23 patients in the primary surgery group, 11 in the secondary surgery group, and 11 in the staged group. Iris ICG angiograms were successfully performed in all patients. No persistent filling defect was detected in the primary and secondary horizontal recti surgery groups or in the secondary or staged vertical and combined vertical rectus groups 6-8 weeks postoperatively. 57% of both primary vertical and combined vertical and horizontal groups showed defects in the early postoperative phase. Only three cases demonstrated late perfusion defects in this series.ICG can detect iris perfusion changes in dark irides after strabismus surgery. Iris reperfusion was achieved in the majority of the cases.

The architecture of the vasculature of the human anterior eye segment was studied by scanning electron microscopy of vascular resin casts. Regarding the major vessels it was found that the perforating branches of the anterior ciliary arteries (ACA) form an anastomozing circle which lies in the posterior portion of the ciliary muscle (intramuscular circle). The ACAs supply the outer and posterior parts of the ciliary muscle, partly the iris, and the peripheral choroid by recurrent ACA branches. The major arterial circle of iris (MACI) which lies more anteriorly is formed mainly by the long posterior ciliary arteries and supplies the inner and anterior portion of the ciliary muscle, the iris and the ciliary processes. The ciliary process vasculature consists of three different vascular territories with discrete arterioles and venules. The first vascular territory which is located at the anterior end of the major processes, is drained posteriorly by venules which pass the ciliary body without greater connections to the venules of the major ciliary processes. The second and third territories comprise the vasculature of the major and minor ciliary processes drained posteriorly by venules which are located at the margin of the ciliary processes. In supravital experiments with human autopsy eyes, a characteristic segment of arterioles supplying the first and second territory was found to be constricted after immersion with epinephrine in a similar way as in cynomolgus monkeys in vivo. Although the general arrangement of the ciliary process vessels is similar to that of the cynomolgus monkey, there are characteristic differences in the size of the territories and in the pattern of the capillary networks. The division of the ciliary process vasculature into three vascular territories may reflect a functional differentiation in the process of aqueous humour production

• Microdissection of the muscular vessels allows recessions, resections, or transpositions of the recti muscles without interrupting the blood flow to the corresponding anterior ciliary arteries. This avoids postoperative impaired blood flow to the anterior segment and may play a role in preventing anterior segment ischemia syndrome. The use of a fine-hooked cannula and microscissors, in addition to the usual strabismus surgery instruments, is described.

To the Editor: We read with interest the article by Trotter et al1 on the treatment of subtotal medial rectus myectomy complicating functional endoscopic sinus surgery. The authors describe the use of a nonabsorbable suture to reattach the cut ends of the medial rectus muscle, which had been partially severed during sinus surgery. Although both patients obtained single vision in primary position, both adduction and abduction were limited after surgery. The authors stated that failure to retrieve the orbital segment of the muscle would have necessitated a medial transposition of the vertical rectus muscles, which would carry a risk of anterior segment ischemia. Muscle-splitting procedures were also suggested as a possible treatment for this hypothetical occurrence, although they stated that this would be less effective than a full-tendon transfer. We have described a modification of the Hummelsheim transposition procedure2 that has been shown to be very effective and does not compromise all of the vertical rectus ciliary arteries. This procedure has been used in a case like that described by Trotter et al in which the orbital portion of the medial rectus muscle could not be retrieved. Our case involved a 63-year-old man who experienced diplopia immediately following endoscopic sinus surgery. He was found to have a large exotropia with an inability to adduct the eye to the midline. Magnetic resonance imaging showed a complete transection of the medial rectus muscle. He underwent strabismus surgery 2 weeks later and the orbital portion of the muscle could not be found. A modified Hummelsheim procedure was then performed. Briefly, the modification involves splitting of the rectus muscles 15 mm posterior to their insertion, making sure that one ciliary artery is left on either side. The medial portion of each muscle was then resected 7 mm, and they were placed at the insertion site of the medial rectus muscle. Five units of Botox was injected into the lateral rectus muscle. Following the procedure, the patient was orthophoric in primary position and had an area of single vision that extended to 10 degrees medial to the midline. We believe that our modification of the Hummelsheim procedure is ideally suited for this type of complicated strabismus problem. Although we agree with Trotter et al that a full-tendon transposition might carry a relatively high risk of anterior segment ischemia, our procedure markedly augments the effect of the split-tendon transposition without completely disrupting the remaining anterior ciliary arteries.

The whole retina, except for the medullary fiber zone in a rabbit eye, is supplied by choroidal circulation. Therefore, the histopathological changes of the sensory retina due to choroidal circulatory disturbance in rabbits may be comparable to that of the human sensory retina in the case of ophthalmic artery occlusion. This study was carried out to evaluate the histopathological changes of the ischemic retina secondary to the occlusion of choroidal circulation. The experimental occlusion of all posterior ciliary arteries and anterior ciliary arteries in the horizontal rectus muscle of rabbit eyes was performed and the subsequent histopathological changes of the sensory retina were observed by transmission electron microscopy. The morphological changes of the sensory retina following the occlusion of the ciliary arterial system are as follows: severe loss of the inner and outer segments of the photoreceptor, mild to moderate degeneration of the ganglion cells, and excellent preservation of the Müller's cell fibers and the extension of the cytoplasmic villous processes to the cytoplasmic vacuolar spaces of other degenerated cells. These findings indicate that the Müller's fibers in the ischemic condition of retina might contribute to the formation of gliosis or scarring of a damaged retina.