Treatment of thyroid associated ophthalmopathy with periocular injections of triamcinolone

AIM

To evaluate the efficacy of periocular triamcinolone acetonide for the treatment of thyroid associated ophthalmopathy (TAO), and the presence of ocular or systemic adverse effects.

METHODS

A multicentre prospective pilot study was performed on patients diagnosed with Graves' ophthalmopathy less than 6 months before entry to the study. Patients were admitted to the study and were randomised into two groups: treatment and control. The treatment group received four doses of 20 mg of triamcinolone acetate 40 mg/ml in a peribulbar injection to the inferolateral orbital quadrant. Both groups were evaluated by measuring the area of binocular vision without diplopia on a Goldmann perimeter and the size of the extraocular muscles on computed tomography (CT) scans. Ophthalmological and systemic examinations were done to rule out ocular and systemic adverse effects. Follow up was 6 months for both groups.

RESULTS

50 patients were eligible for the study. 41 patients completed the study. There was an increase in the area of binocular vision without diplopia in the treatment group (Sigma initial: mean 231.1 (SD 99.9) and final absolute change, mean 107.1 (SD 129.0)) compared to the control group (Sigma initial: mean 350.7 (SD 86.5) and final absolute change, mean -4.5 (SD 67.6)). The sizes of the extraocular muscles were reduced in the treatment group (mean (inferior rectus initial values): 1.3 (0.7), final percentage change: -13.2 (25.7), medial rectus initial values: 1.2 (0.6), final percentage change: -8.2 (20.7), superior rectus-levator palpebrae initial values: 1.2 (0.6), final percentage change: -9.5 (29.1), lateral rectus initial values: 1.0 (0.4), final percentage change: -11.5 (20.6)) compared to the control group (inferior rectus initial values: 0.9 (0.3), final percentage change: -4.0 (21.5), medial rectus initial values: 0.9 (0.3), final percentage change: 0.6 (22.4), superior rectus-levator palpebrae initial values: 0.9 (0.3), final percentage change: 12.5 (37.5), lateral rectus initial values: 0.9 (0.4), final percentage change: -0.5 (31.6)). Both measurements (degree of diplopia and muscle thickness) were statistically significant between groups (initial - final). No systemic or ocular adverse effects were found.

CONCLUSIONS

Triamcinolone administered as a periocular injection is effective in reducing diplopia and the sizes of extraocular muscles in TAO ophthalmopathy of recent onset. This form of treatment is not associated with systemic or ocular side effects.

Vertical diplopia following peribulbar anesthesia: the role of hyaluronidase

PURPOSE

To estimate the incidence of vertical diplopia following peribulbar anesthesia in otherwise uncomplicated cataract surgery and to establish whether the use of hyaluronidase in the peribulbar injection mixture affected the likelihood of this complication.

METHODS

Nine hundred forty consecutive phacoemulsification procedures using peribulbar anesthesia were retrospectively reviewed to identify cases of postoperative vertical diplopia. Case notes were reviewed to establish the nature and timing of the onset of diplopia, the anesthetic technique, and whether hyaluronidase was used. The patterns of progression as demonstrated by serial Hess charts were compared.

RESULTS

There were 6 cases of vertical diplopia (incidence, 0.64%). All showed an immediate postoperative hypertropia in the injected eye changing during a 4- to 6-week period to hypotropia with restriction of upgaze. All applications of anesthesia were administered by consultant anesthetists, associate specialists, or residents under their direct supervision using 25-mm, 25-gauge needles with 2% lidocaine. Hyaluronidase was included in the injection mixture for 435 (46%) of the cases and was not included for 505 (54%) of the cases. All 6 cases of vertical diplopia occurred in the group in which hyaluronidase was not used, which has a significant association (chi-square test, 5.22; P = .023).

CONCLUSION

Hyaluronidase should be included in peribulbar anesthetics to reduce the risk of postoperative vertical diplopia.

Accuracy of clinical estimation of abnormal head postures

PURPOSE

Correct diagnosis and analysis of an abnormal head posture (AHP) is critical in the clinical assessment of patients with strabismus and nystagmus. This study was performed to evaluate the accuracy and precision of clinicians estimating the degree of face turns and head tilts.

DESIGN

Experimental simulation study.

PARTICIPANTS

Two normal volunteers and 4 pediatric and 1 general ophthalmologists.

METHODS

Using a cervical range of motion (CROM) device, single axis head position (chin up, chin down, right and left face turn, and head tilts) were modeled, and clinical estimates of the amount of deviation were estimated by the four ophthalmologists. Each of the 4 examiners estimated 108 single axis AHPs in a randomized and masked pattern.

MAIN OUTCOME MEASURES

Accuracy of clinical estimation of AHP, intra- and inter- observer variability, and variability in terms of head position.

RESULTS

The examiners tended to overestimate the AHPs by an average of 5 degrees (P less than 0.001). Two "right" positions (right head tilt and face turn) were the worst. The average error was 10 +/-8 degrees for the right tilt and turn positions, while the error for all other positions, excluding these two, averaged 0 +/-10 degrees (P = 0.0001).

CONCLUSIONS

Clinical estimation of an AHP by ophthalmologists is in part remarkably accurate, even if imprecise, but some positions, notably right head tilt and right face turn in this study, were significantly overestimated. Objective methods of measuring AHPs such as the CROM may be preferable for these RHT and RFT AHPs and when maximum precision is needed for tracking changing AHPs or deviations.

Medial and lateral orbital wall surgery for balanced decompression in thyroid eye disease

OBJECTIVES/HYPOTHESIS

Diplopia remains a major potential complication of orbital decompression performed for thyroid eye disease. We sought to examine the effect of medial and lateral wall surgery with sparing of the orbital floor on the incidence of postoperative diplopia.

STUDY DESIGN

Retrospective review.

METHODS

A retrospective review was made of 63 consecutive medial and lateral orbital wall surgeries (40 patients) performed between December 1996 and May 2002 for orbital decompression of thyroid eye disease.

RESULTS

The average patient age was 50.9 years of age (age range, 14-83 y). The studied group was predominantly female (sex ratio, 36:4). Indications were compressive optic neuropathy (34), exposure keratopathy (25), and aesthetic concerns (4). The mean time since surgery was 31.5 months (range, 3-69 mo). The medial wall was approached by a transcaruncular (59) or endoscopic (4) technique. Two patients had fat removal. The average improvement in exophthalmos was 4.1 mm (range, 0-10 mm). The average palpebral fissure improvement was 2.0 mm (range, 0-7 mm). Two patients had cerebrospinal fluid leaks during excavation of the sphenoid bone. These were diagnosed and repaired primarily without complication. New-onset diplopia occurred in four patients. Two of these patients required strabismus surgery.

CONCLUSION

A 10% new-onset diplopia rate compares favorably with other surgical series. Medial and lateral wall surgery only, sparing the floor, may reduce diplopia after surgery for orbital decompression in thyroid eye disease.

Diplopia after refractive surgery: occurrence and prevention

OBJECTIVES

To report the occurrence of persistent diplopia manifesting after refractive surgery, to describe the different causes of this complication, to provide risk stratification for its occurrence, and to outline minimal screening techniques for its prevention.

METHODS

A retrospective medical record review of patients seen in 2 private strabismus practices who experienced persistent diplopia after refractive surgery.

RESULTS

A total of 28 patients were identified who met the inclusion criteria. The causes of postoperative diplopia could be traced to 1 of 5 mechanisms. These included technical problems, prior need of prisms, aniseikonia, iatrogenic monovision, and improper control of accommodation in patients with strabismus. The recommended screening techniques would have identified all patients in this series as being at risk for postoperative diplopia with the exception of those in whom technical problems were responsible.

CONCLUSIONS

Diplopia can become manifest after refractive surgery. With proper attention paid to risk stratification and recommended screening criteria, the incidence of this complication can be minimized.

Orbital floor reconstruction with flexible Ethisorb patches: a retrospective long-term follow-up study

OBJECTIVE

The purpose of the study was to investigate whether a flexible, biodegradable material (Ethisorb) shows better long-term results with regard to diplopia, bulbus motility, and exophthalmos/enophthalmos compared to the use of lyophilized dura-patches and polydioxanone (PDS) foils.

METHODS

During a period of 6 years 435 patients with an orbital fracture were investigated retrospectively. Inclusion criteria were patients with fractures of the orbital floor with a maximum size of 2 x 2 cm. Bulbus motility, exophthalmos, enophthalmos, and diplopia were investigated during a period of 2 years.

RESULTS

One hundred twenty orbital floors were reconstructed by lyophilized dura-patches, 81 by PDS, and 136 by Ethisorb. An exploration without an implantation was performed in 91 patients. The long-term investigation 12 to 15 months after surgery showed an exophthalmos and enophthalmos incidence of 1%, whereas a reduced bulbus motility and diplopia were found in 5% and 4%, respectively. Fifteen to 24 months after surgery 2% of the patients had an exophthalmos and 1% had an enophthalmos. A reduction of bulbus motility was found in 4% of the patients, and diplopia was found in 3%. The use of Ethisorb resulted in a significantly lower incidence of exophthalmos 3 months after surgery compared to PDS.

CONCLUSION

The low rate of acquired bulbus motility demonstrates acceptable results in using Ethisorb in the floor of the orbit.

Endoscopic transnasal orbital decompression for thyrotoxic orbitopathy

OBJECTIVE

To evaluate the efficacy of endoscopic transnasal orbital decompression alone for thyrotoxic orbitopathy.

DESIGN

Retrospective review of consecutive procedures.

SETTING

Tertiary referral otorhinolaryngology centre.

PATIENTS

Twenty-three eyes of 14 patients.

INTERVENTION

Endoscopic transnasal orbital decompression.

MAIN OUTCOME MEASURES

Proptosis reduction, intra-ocular pressure reduction, exposure keratitis reduction, visual acuity improvement, and complication rate.

RESULTS

There were no surgical complications for the 23 orbital decompressions. Proptosis reduction was achieved in 22 (96%) eyes. The mean proptosis reduction was 4.6 mm (median, 5.0 mm; range, 1.0-8.0 mm). The postoperative intra-ocular pressure decreased after surgical decompression in 20 (87%) eyes with a mean reduction of 11 mm Hg (median, 6 mm Hg; range, 1-35 mm Hg). Of the 15 eyes with incomplete closure of the eyelid before the operation, 11 (73%) had complete eyelid closure after surgical decompression. Of the other four eyes that had incomplete closure, the gaps were reduced. The visual acuity was improved for 16 (70%) eyes with a median improvement of 3 Snellen lines (range, 1-8 lines).

CONCLUSION

Endoscopic transnasal medio-inferior orbital wall decompression is a safe and adequate treatment for thyrotoxic orbitopathy with proptosis, exposure keratitis, and visual loss.

Thyroid and the eye

Any thyroid cancer can metastasize to the uveal tract, even after decades; medullary thyroid cancer can be part of multiple endocrine neoplasia syndrome. Superior limbic keratoconjunctivitis and lagophthalmos are prognostic markers for more severe thyroid-associated ophthalmopathy (TAO). The restrictive ophthalmopathy of TAO may be associated with more sustained ocular hypertension and require topical therapy. Several new studies address the therapy of TAO, ranging from retrobulbar to oral to intravenous glucocorticoids, alone or combined with radiotherapy. Endonasal decompression of the posterior orbit can be done well for severe optic nerve compression; however, leaving the anterior orbital septum intact can minimize postoperative diplopia. Smoking increases the risk and relapse rate for ophthalmopathy. Thyrotropin receptor antigen on fibroblasts diffusely in the body is causative in TAO and pretibial myxedema with even increased urinary secretion of glycosaminoglycans. Corticosteroid-responsive patients show a sustained up-regulation of the Th1/Th2 profile.

Reduction of diplopia following endoscopic orbital decompression: the orbital sling technique

OBJECTIVE

Although endoscopic orbital decompression has become the surgical treatment of choice for patients with proptosis from Graves disease, postoperative diplopia requiring corrective eye muscle surgery can occur in up to 63% of patients. The purpose of the study was to evaluate a new technique intended to reduce the incidence of diplopia following endoscopic orbital decompression.

STUDY DESIGN

Case-control.

METHODS

Endoscopic orbital decompression was performed on 58 orbits in 37 patients with proptosis from Graves disease. The orbital sling technique, which makes use of a horizontal strip of periorbital fascia to prevent prolapse of the medial rectus muscle, was used on 20 orbits in 13 patients. Conventional endoscopic decompression was performed in 24 control subjects. The mean duration of follow-up was 3.3 +/- 1.3 years (range, 1.7-5.1 y).

RESULTS

The incidence of new-onset or worsened diplopia following endoscopic decompression was significantly lower for the orbital sling group compared with control subjects (0% vs. 29.2%, respectively [ =.038]). No patients in the orbital sling group developed new-onset diplopia following surgery. Of the eight patients with pre-existing diplopia from the orbitopathy, double vision improved in four patients (50%) and was unchanged in the remaining four patients (50%). The mean reduction in proptosis was comparable for the orbital sling and control groups (5.1 +/- 1.1 mm vs. 5.0 +/- 1.9 mm, respectively [ P=.98]). CONCLUSIONS The preservation of a fascial sling overlying the medial rectus muscle during endoscopic orbital decompression appears to reduce the incidence of postoperative diplopia, while still allowing for a satisfactory reduction in proptosis. This modification of the standard decompression technique should be considered for the treatment of patients with proptosis.

Transnasal endoscopic orbital decompression and Graves' ophtalmopathy

AIM OF THE STUDY

To assess the validity and the limits of endoscopic endonasal orbital decompression for Graves' ophtalmopathy resistant to the medical theapy.

MATERIAL AND PATIENTS

Between September 1994 and May 1998, 16 patients with Graves' ophtalmopathy resistant to the medical treatment underwent an orbital decompression transnasally. 27 orbits were decompressed. The surgery was bilateral in 11 patients. In the 5 remaining cases, the surgery was unilateral. It was carried out on the left side in 2 cases and on the right side in 3 cases.

RESULTS

Preoperatively, the average visual acuity was 8/10. Postoperatively, the visual acuity was 9.5/10. The average preoperative exophtalmometry measurement was 25.04 mm and the average postoperative measurement was 21.83 mm. The average retrodisplacement was 3.17 mm (range: 2-8). Preoperatively, 3 patients had mild diplopia whereas 5 others had moderate to severe extraocular muscle dysfunction. Postoperatively, 6 patients had mild diplopia whereas 10 patients required squint surgery for moderate to severe extraocular muscle dysfunction.

CONCLUSION

Endoscopic orbital decompression improve all the symptoms of Graves' ophtalmopathy but one: the extraocular muscle dysfunction. Its cardinal indication is the treatment of compressive optic neuropathy whereas this surgical approach provides an excellent control of the medial wall of the orbit and the orbital apex. But the average reduction of proptosis of 3.17 mm is not high enough to propose this approach alone for the treatment of disfiguring proptosis. In such cases, a 2 or 3 wall orbital decompression should be performed to get marked cosmetic and functional improvement. In all cases, the patient should be informed about the risk of postoperative diplopia.

The use of titanium mesh in the management of orbital trauma--a retrospective study

This study examines the use of titanium mesh in the reconstruction of internal orbital defects. The goals of reconstruction when treating orbital fractures include restoration of internal wall continuity and provision of support to the orbital contents. In this way the untoward sequelae of post-traumatic enophthalmos and disturbance of visual acuity are avoided. Autogenous grafts have been the material of choice for most surgeons involved with treatment of these injuries. The major disadvantages of using autologous tissue are the need for a graft donor site, with attendant increases in operative time, prolonged hospitalization, increased postoperative discomfort and problems intrinsic to the donor site wound. The purpose of this report is to present the author's experience with the use of titanium alloplasts in the early repair of traumatic orbital wall fractures. Patients treated at the Townsville General Hospital from July 1, 1997-March 1, 2000 with injuries involving the orbit repaired with titanium mesh or micro-mesh were included in the study.

[Vertical diplopia after cataract operation]

PURPOSE

Presentation and analysis of patients with vertical diplopia appearing after cataract surgery in retrobulbar anesthesia.

SUBJECTS AND METHODS

Between 1990 and 1998 9 Patients with vertical diplopia following cataract surgery in retrobulbar anesthesia were studied in our Orthoptic Department. Each patient had complete orthoptic examination with Hess-screen-test. Additionally, some patients underwent neuroradiologic imaging and forced-duction testing.

RESULTS

We subdivided the patients in a group of 4 patients with hypertropia and of 5 patients with hypotropia of the operated eye. All hypotropias were left-sided. Seven patients showed an overaction of the involved muscle without regression. Seven patients underwent surgery of a vertical muscle. Only 1 patient needed prismatic therapy postoperatively. The other 2 non-operated patients were satisfied with prisms alone.

CONCLUSIONS

The proposed pathogenesis of vertical diplopia in these cases is fibrosis and contracture of the injured muscle, which could be due to anesthetic myotoxicity after direct injection into the muscle or to an intramuscular hemorrhage. On the other hand hypertropia could be a result of placement of bridle sutures. We discuss prevention and therapy of such complications.

Modified orbital decompression for dysthyroid orbitopathy

PURPOSE

The transantral approach to orbital decompression remains useful for the management of exophthalmos associated with dysthyroid orbitopathy. However, the risk of postoperative diplopia is a concern. Preservation of the anterior periorbita may help support the orbital contents and decrease the incidence of diplopia.

METHODS

The medical records were reviewed of 15 consecutive patients who underwent 30 transantral orbital decompressions for proptosis associated with dysthyroid orbitopathy. The procedures were completed in standard fashion, including removal of the inferomedial bony strut between the medial orbital wall and the floor. However, stripping of the periorbita was only done posteriorly; the anterior 10 to 15 mm of periorbita were left intact.

RESULTS

Six patients had preoperative diplopia that persisted after decompression. Of the nine patients without diplopia preoperatively, none developed diplopia. Proptosis was reduced a mean of 3.5 +/- 2.6 mm.

CONCLUSIONS

Preservation of the anterior periorbita during transantral orbital decompression reduces the risk of postoperative diplopia. An adequate reduction in proptosis is also achieved.

Endoscopic orbital decompression with preservation of an inferomedial bony strut: minimization of postoperative diplopia

With the increasing sophistication and safety of endoscopic orbital decompression, the technique is seen by many as an attractive and less morbid alternative to traditional open techniques. This rationale also makes the procedure more acceptable for individuals considering decompression for cosmetic reasons. As a result, complications such as postoperative diplopia assume greater significance. Preservation of an inferomedial bony strut has been postulated to reduce the incidence of postoperative diplopia in transconjunctival, but not endoscopic, orbital decompression for dysthyroid ophthalmopathy. We present a consecutive series of 11 subjects (21 eyes) who underwent transnasal endoscopic medial and inferior decompression of the orbits bilaterally. All patient charts were reviewed in a retrospective fashion and ophthalmologic, surgical, and cosmetic data were recorded, with callback of patients with incomplete data sets. All cases were performed under general anaesthesia. Preservation of the strut was possible in 15 of 21 eyes. Visual acuity was preserved or improved in all 21 eyes. Average ocular recession based on Hertel measurements was 3.6 mm and there were no surgical complications. New-onset or worsening diplopia was noted postoperatively in 2 of 11 subjects. However, in patients where both struts were preserved, there was zero incidence of postoperative diplopia (0/6). These results indicate that preservation of an inferomedial bony strut is not only technically feasible but also does not compromise the adequacy of decompression. The results also suggest that preservation of the inferomedial bony strut during endoscopic orbital decompression can reduce the incidence of postoperative diplopia.

Cluster of diplopia cases after periocular anesthesia without hyaluronidase

PURPOSE

To describe a cluster of cases of iatrogenic diplopia after cataract surgery that occurred in 1998, when hyaluronidase was unavailable for use in periocular anesthetic regimens.

SETTING

The clinical practices of the authors.

METHODS

This study comprised a retrospective chart review.

RESULTS

Twenty-five cases of transient or permanent diplopia were reported. Of these, 13 eyes had retrobulbar and 10 had peribulbar injections; in 2 cases the injection technique was unknown. The inferior rectus was affected in 19 eyes; of these, 1 had a temporary palsy and 18 had permanent restriction. Temporary paresis developed in the lateral rectus in 5 cases and the superior rectus in 2. Eleven cases were submitted by 4 anterior segment surgeons, who collectively had a zero incidence of iatrogenic postoperative diplopia in the preceding 4 to 11 years of practice (approximately 6900 cases).

CONCLUSION

Hyaluronidase may be more important than previously suspected in preventing anesthetic-related damage to the extraocular muscles. The inferior rectus muscle is particularly vulnerable, presumably because of the injection technique.

Botulinum toxin in childhood strabismus

The use of botulinum toxin A (BTXA) in childhood strabismus is still a matter of debate. This study investigates the indications for and outcome of BTXA therapy in children at our institution. From 1985 to 1995, 237 children up to and including 16 years of age were treated with BTXA for strabismus. We undertook a retrospective study of 163 (69%) children from this group. Factors considered were age; anaesthesia; number of, indication for and outcome of injections; complications and follow-up. There were three major indications for the use of BTXA in children: firstly to improve binocular function, secondly as a post-operative diplopia test or for cosmetic reasons, and thirdly in the investigation or treatment of paralytic and restrictive strabismus. In the first group (54 children), BTXA produced improved binocular function in 54% of all patients treated and in 49% of those with a minimum follow-up of 12 months. In the second group (82 children), 88% showed informative post-operative diplopia tests and 44% had more than one injection to maintain improved cosmetic alignment. The third group comprised 27 children with a range of diagnoses, including 1 third nerve paresis, 12 unilateral or bilateral sixth nerve pareses, 7 unilateral or bilateral Duane's syndromes, 5 lost or fibrosed muscles and 2 others. This group had a range of outcomes which are discussed in the text. BTXA is useful in the treatment of a select group of children with strabismus. If there is evidence of threatened or recently lost binocularity, or risk of creating or worsening diplopia after surgery, it is a useful therapeutic tool. In children with strabismus of unusual cause it has diagnostic value.

Long-term results of botulinum toxin in consecutive and secondary exotropia: outcome in patients initially treated with botulinum toxin

INTRODUCTION

Long-term ocular alignment can be difficult to achieve in patients with consecutive and secondary (sensory) exotropia, and botulinum neurotoxin A (BTXA) is a recognized alternative to surgery in this group.

PATIENTS AND METHODS

We reviewed the results of 44 patients aged 15 to 77 years (mean 31 years) who underwent their first BTXA injections from 1989 to 1990. In 30% of cases the choice of toxin treatment was made by the patient. In the remainder BTXA was recommended by the clinician to assess the risk of postoperative diplopia. Thirty-three patients (75%) were consecutively exotropic and 68% of patients had had previous strabismus surgery. The mean preinjection deviation was 41 delta of exotropia (range 12 to 85 delta exotropia) and the minimum mean angle change after 1 injection was 27 delta (range 0 to 57 delta). The average number of injections was 3 (range 1 to 17).

RESULTS

Of the patient group, 59% went on to strabismus surgery, 14% continued to attend for maintenance treatment, and 9% were discharged with a small, stable deviation. The remainder were either followed up elsewhere or failed to reattend.

CONCLUSIONS

Botulinum toxin appears to be a satisfactory treatment for constant exotropia in patients at risk of postoperative diplopia who have undergone multiple operations but, because more than half the group went on to surgery, surgery as a first therapy may be preferable in uncomplicated cases.

[Oculomotor risk after trans-palpebral bony decompression for thyroid-related orbitopathy]

PURPOSE

To study oculomotor disorders after transpalpebral bony orbital decompression (TPBOD) for dysthyroid orbitopathy. Pathophysiology, risk factors, preventive and therapeutic care were examined.

MATERIAL AND METHODS

Forty-four patients were included in this retrospective study (76 orbits). Thirteen patients underwent surgery for severe orbital inflammation or optic neuropathy and 31 for cosmetic rehabilitation. 21 previously had orbital radiotherapy. Class IV of NOSPECS classification, primary position of gaze, diplopia and Lancaster coordimetry were studied comparatively pre and postoperatively.

RESULTS

Diplopia appeared in 23.6% of the cases without deviation before surgery (tropia or phoria-tropia). Predictive factors were age and amblyopia whereas amount of retrodisplacement of the globe and radiotherapy were not. Lack of oculomotor restriction did not prevent from diplopia but may decrease its incidence. Unilateral decompression is more likely to create a vertical disorder. Pathophysiology is discussed.

CONCLUSION

Oculomotor disorders can be explained by several mechanisms. Some of them can be prevented. Each patient should be aware of the risk of diplopia.

Diplopia following subcutaneous injections of botulinum A toxin for facial spasms

PURPOSE

To study the incidence, cause, recovery time, and prevention of diplopia following subcutaneous injection of botulinum A toxin for the treatment of facial spasms.

METHODS

Patients who experienced diplopia after botulinum A toxin injections had their deviations examined in detail. When the muscle that caused diplopia was identifiable, the injection closest to that muscle was omitted in the next treatment in an attempt to prevent diplopia.

RESULTS

Of 250 patients receiving about 1500 sets of injections, 25 (1.7%) incidents of diplopia occurred in 10 patients. Excluding two patients who declined further treatment after having diplopia on their first botulinum A toxin treatment, seven of the remaining eight patients had multiple incidents of diplopia. The most common pattern of diplopia was "uncertain diagnosis." The most common identifiable cause of diplopia was paresis of the inferior oblique muscle. Omission of the injection into the central portion of the lower eyelids in the next treatment prevented recurrence of diplopia in only one of the four patients. No significant correlation between botulinum A toxin doses injected and times to recovery was noted.

CONCLUSIONS

Diplopia following botulinum A toxin treatment is uncommon. Seven patients (3% of patients studied) had 22 episodes of diplopia (88% of episodes). When diplopia occurs, it tends to recur on reinjection, sometimes with a prolonged recovery time. This response may not be dose dependent. The extraocular muscles of some patients may be more susceptible to chemodenervation than others, or botulinum A toxin may diffuse to extraocular muscles more easily in some patients than in others.

Compensation procedures for the anisometropic presbyope

When changing to bifocal lenses from distance anisometropic lenses, presbyopic patients may experience diplopia when attempting to do close work. Prescription failure can be dramatically reduced by utilizing the procedures outlined in this article. Why would a patient experience diplopia when attempting to read with bifocals? The diplopia may simply be a result of the optical difference in power between the two lenses. Anisometropia creates a disparity in the size of the retinal image as well as a prismatic imbalance when looking away from the optical center. A practical approach to coping with these problems is recommended.