Diplopia after refractive surgery: occurrence and prevention

Refractive surgery as a treatment tool for strabismus: systematic review

The impact refractive surgery has on preoperative horizontal strabismus is rapidly evolving, and this knowledge can provide valuable clinical context when considering refractive surgery as a treatment for strabismus. 515 studies were identified, of which 26 met the inclusion criteria. Analysis indicated that refractive surgery resulted in an overall decrease in the mean uncorrected postoperative angle of deviation caused partially or fully due to refractive error and highlighted the varied outcome of refractive surgery on nonaccommodative horizontal strabismus with limited evidence to suggest refractive surgery for this type of strabismus. Efficacy of refractive surgery in reducing concomitant horizontal strabismus depends on several factors: type of horizontal ocular deviation, patient age, and extent of refractive error. Refractive surgery can be an effective treatment for refractive accommodative horizontal strabismus in patients with stable, mild to moderate myopia or hyperopia and should be considered with careful patient selection for optimum outcome.

Changes in accommodation and convergence function after refractive surgery in myopic patients

In recent years, with the gradual maturation of myopia correction surgery, the changes in binocular visual function after surgery have attracted widespread attention. The accommodation of facility, the amplitude of accommodation, relative accommodation, and accommodation convergence/accommodation assembly are essential parameters for assessing binocular visual function. The changes in these parameters are significant for guiding patients in the design of the preoperative surgical approach and alleviating postoperative visual fatigue. This paper aims to guide the preoperative assessment, design, and postoperative visual training of refractive surgery in myopic patients from the perspective of changes in binocular visual function before and after myopia and surgery, which can improve accommodation and convergence function in patients after refractive surgery.

Diplopia and Strabismus After Corneal Refractive Surgery

INTRODUCTION

Diplopia and strabismus are known complications after corneal refractive surgery (CRS). Within the U.S. Armed Forces, refractive surgery is used to improve the operational readiness of the service member, and these complications could cause significant degradation to their capability. This study was performed in order to identify the incidence of strabismus and diplopia following CRS within the U.S. Military Health System.

METHODS

A retrospective review of all patients who underwent photorefractive keratectomy (PRK) or laser-assisted in situ keratomileusis (LASIK) in the Department of Defense from January 2006 through September 2013 was designed and approved by the Naval Medical Center Portsmouth Institutional Review Board. The military health system data mart was queried for all patients who underwent one of these procedures and subsequently had an International Classification of Disease-9 code for any strabismus or diplopia through 2014 allowing at least 1 year of follow-up. We then calculated the incidence of both diplopia and strabismus for these procedures as the primary measure and the overall prevalence as a secondary measure.

RESULTS

A total of 108,157 patients underwent PRK or LASIK during our study period with 41 of these patients subsequently having a diagnosis of diplopia or strabismus. After chart review, 16 of these patients were excluded resulting in 25 patients for inclusion in either the strabismus (23 patients, 0.02%) or diplopia (3 patients, 0.003%) cohorts with one patient having both. Of the 23 patients with postoperative strabismus, 4 were new cases giving an incidence of 0.004% and 2 new cases of diplopia for an incidence of 0.002%.

CONCLUSION

Diplopia and strabismus are rare complications after CRS in the U.S. military population. These procedures continue to increase the operational readiness of our service members with minimal risk of these potentially debilitating complications. Overall, this study provides support for the continued use of PRK and LASIK despite study limitations related to the use of large databases for retrospective review. Future prospective studies using delineated preoperative and postoperative examinations with sensorimotor testing included may be able to resolve the limitations of this study.

Effect of corneal refractive surgery on accommodative and binocular dysfunctions among civilian pilots in Southwest China

Background

To analyze whether corneal refractive surgery (CRS) is associated with the distribution of different accommodative dysfunctions (ADs) and binocular dysfunctions (BDs) in civilian pilots. A further aim was to analyze the percentages and visual symptoms associated with ADs and/or BDs in this population.

Methods

One hundred and eight civilian pilots who underwent CRS from January 2001 to July 2012 (age: 30.33 ± 4.60 years) were enrolled, the mean preoperative SE was − 1.51 ± 1.15 D (range: − 1.00- − 5.00 D). Ninety-nine emmetropic civilian pilots (age: 29.64 ± 3.77 years) who were age- and sex-matched to the CRS group were also enrolled. Refractive status, accommodative and binocular tests of each subject were performed. Visually related symptoms were quantified using the 19-item College of Optometrists in Vision Development Quality of Life (COVD-QOL) questionnaire. The 19 items were summed to obtain visual symptom scores that might indicate visual dysfunctions. The chi-square test was used to analyze differences in percentages of ADs and/or BDs between the CRS and emmetropic groups. The Mann-Whitney U test was used to compare visual symptom scores between pilots with ADs and/or BDs and pilots with normal binocular vision.

Results

No significant difference was observed between the CRS and emmetropic groups in the overall prevalence of ADs and BDs (15.7% and 15.2% in the CRS and emmetropic groups, respectively; P = 0.185). ADs were present in 4.63% and 3.03% of the CRS and emmetropic group, respectively. BDs were observed in 11.1% and 12.1% of the CRS and emmetropic group, respectively, yielding no significant differences between the groups in the prevalence of ADs or BDs (AD: P = 0.094; BD: P = 0.105). Pilots with ADs and/or BDs had significantly more visual symptoms than pilots with normal binocular vision (p < 0.001).

Conclusions

CRS for civilian pilots with low-moderate myopia might not impact binocular functions. ADs and/or BDs commonly occur in both emmetropia pilots and pilots who undergo CRS, and pilots with ADs and/or BDs are associated with increased symptoms. This study confirms the importance of a full assessment of binocular visual functions in detecting and remedying these dysfunctions in this specific population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-01855-0.

Binocular Triplopia Due to Decompensated Congenital Superior Oblique Paresis in A Patient with Marfan Syndrome; A Case Report and Review of Literature

Binocular triplopia is a rare symptom and usually has a corneal or lenticular origin. Uniocular diplopia arising from ectopia lentis is quite common in Marfan syndrome. A visual phenomenon related to binocular triplopia due to strabismus was first reported in 1943 by Burian. Both monocular diplopia and binocular triplopia have been reported in concomitant strabismus. Strabismus is also common in Marfan syndrome but congenital superior oblique paresis has never been reported before. We report herein a rare case of binocular triplopia in a patient with Marfan syndrome arising from decompensation of his coexistent congenital superior oblique paresis triggered by his uniocular diplopia. This is the first report of congenital superior oblique paresis in a patient with Marfan syndrome. Though it is unlikely to have any etiological implications and is likely to be a mere coincidental simultaneous occurrence, it had a confounding effect on the clinical interpretation of the signs and symptoms posing an interesting diagnostic and management dilemma. Our case report emphasizes the necessity for careful evaluation of any patient with symptoms of triplopia. We further review and summarize all the causes of binocular triplopia published in English literature and propose an approach to its evaluation and management.

Binocular vision alterations after refractive and cataract surgery: a review

To review binocular and accommodative disorders documented after corneal or intraocular refractive surgery, in normal healthy prepresbyopic patients. A bibliographic revision was performed; it included works published before 1st July 2017 where accommodation and/or binocularity was assessed following any type of refractive surgical procedure. The search in Pubmed yielded 1273 papers, 95 of which fulfilled the inclusion criteria. Few publications reporting binocular vision and/or accommodative changes after refractive surgery in normal subjects were found. The reduction in fusional vergence is the most frequently reported alteration. Anisometropia is an important risk factor for postoperative binocular vision-related complaints. Most diplopia-related visual complaints, irrespective of the surgical procedure, were in fact misdiagnosed preoperative disorders. The preoperative evaluation of patients seeking spectacle/contact lens independence should include a complete binocular and accommodation assessment where parameters such as the phoric posture, accommodative amplitude and facility, near point of convergence, fusional reserves and accommodative convergence/accommodation coefficient are measured. This would allow the identification of risk factors that could compromise the success of the refractive surgery and cause clinical symptoms.

Strabismus After Ocular Surgery

Many types of ocular surgery can cause diplopia, including eyelid, conjunctival, cataract, refractive, glaucoma, retinal, and orbital surgery. Mechanisms include direct injury to the extraocular muscles from surgery or anesthesia, scarring of the muscle complex and/or conjunctiva, alteration of the muscle pulley system, mass effects from implants, and muscle displacement. Diplopia can also result from a loss of fusion secondary to long-standing poor vision in one eye or from a decompensation of preexisting strabismus that was not recognized preoperatively. Treatment, which typically begins with prisms and is followed by surgery when necessary, can be challenging. In this review, the incidence, mechanisms, and treatments involved in diplopia after various ocular surgeries are discussed. [J Pediatr Ophthalmol Strabismus. 2017;54(5):272-281.].

Sensory eye balance in surgically corrected intermittent exotropes with normal stereopsis

Surgery to align a deviated or strabismic eye is often done for both functional as well as cosmetic reasons. Although amblyopia is often an impediment to regaining full binocularity in strabismics in general, intermittent exotropes, because their deviation is intermittent, have no amblyopia and some degree of stereopsis. Binocular function, including a balanced ocular dominance, could be expected to be normal after surgical correction if normal levels of stereopsis and visual acuity are postsurgically achieved. Here we used a binocular phase combination paradigm to quantitatively assess the ocular dominance in a group of surgically corrected intermittent exotropes who have normal stereo and visual acuity as defined clinically. Interestingly, we found significant interocular imbalance (balance point < 0.9) in most of the surgically treated patients (8 out 10) but in none of the controls. We conclude that the two eyes may still have a residual sensory imbalance in surgically corrected strabismus even if stereopsis is within normal limits. Our study opens the possibility that a further treatment aimed at re-balancing the ocular dominance might be necessary in surgically treated intermittent exotropia to provide more efficient binocular processing in the long term.

Impact of laser refractive surgery on ocular alignment in myopic patients

PURPOSE

To evaluate the impact of myopic keratorefractive surgery on ocular alignment.

METHODS

This prospective study included 194 eyes of 97 myopic patients undergoing laser refractive surgery. All patients received a complete ophthalmic examination with particular attention to ocular alignment before and 3 months after surgery.

RESULTS

Patients with a mean age of 26.6 years and a mean refractive error of -4.83 diopters (D) myopia were treated. Asymptomatic ocular misalignment was present preoperatively in 46 (47%) patients: a small-angle heterophoria (1-8 prism diopters, PD) in 36%; and a large-angle heterophoria (>8 PD)/heterotropia in 11%. Postoperatively, the change in angles of 10 PD or greater occurred in 3% for distance and 6% for near fixation: in 7% of the patients with orthophoria, in 3% of those with a small-angle heterophoria, and in 18% of those with a large-angle heterophoria/heterotropia. No patient developed diplopia. The preoperative magnitude of myopia or postoperative refractive status was not related to the change in ocular alignment. The higher anisometropia was associated with a decrease in deviation (P=0.041 for distance and P=0.002 for near fixation), whereas the further near point of convergence tended to be related with an increase in near deviation (P=0.055).

CONCLUSIONS

Myopic refractive surgery may cause a change in ocular alignment, especially in cases with a large-angle heterophoria/heterotropia. There is also a chance of improvement of misalignment in patients with anisometropia.

Iatrogenic diplopia [corrected]

Diplopia is a very disturbing condition that has been reported as a complication of several surgical procedures. The following review aims to identify the ocular and nonocular surgical techniques more often associated with this undesirable result. Diplopia is reported as an adverse outcome of some neurosurgical procedures, dental procedures, endoscopic paranasal sinus surgery, and several ophthalmic procedures. The most common patterns and some recommendations in order to prevent and treat this frustrating outcome are also given.

Strabismus following implantable anterior intraocular lens surgery

Strabismus in adults is increasing and has recently become an important focus of attention due to the development of refractive surgery techniques. In this case, permanent strabismus developed in a woman with previous high myopia after implantable anterior intraocular lens surgery. An ophthalmologic examination revealed the presence of a lens which was placed slightly downward in relation to the center of visual axis in the anterior chambers and up-drawn pupils in both eyes. The prismatic effect due to lens decentration may be the main cause of strabismus. Therefore, we suggest precise intraocular lens insertion and placement technique during surgery as well as careful ophthalmologic assessment including cover/uncover tests in all candidates for refractive surgery and full ocular motility evaluation if there is any doubt about binocular issues.

Diplopia after laser in situ keratomileusis (LASIK) in a patient with a history of strabismus

In patients with a history of strabismus, refractive surgery can result in decompensation of ocular alignment, with subsequent diplopia. Refractive surgery in the management of strabismus has been described, although it remains controversial. We present a young adult with past history of strabismus surgery and new-onset diplopia after refractive surgery. Binocular diplopia was treated surgically with laser in situ keratomileusis.

Strabismus precipitated by monovision

PURPOSE

To present patients who had the onset of strabismus or the recurrence of strabismus after converting to a monovision system of seeing.

DESIGN

Retrospective interventional case series.

METHODS

Clinical records of 12 patients from the private practice of the corresponding author of this paper (Z.F.P.) were reviewed. Patients obtaining monovision via contact lenses, LASIK, and cataract surgery with posterior chamber intraocular lenses were studied if their monovision produced a new strabismus or was related to the recurrence of a previous strabismus.

RESULTS

All patients were first treated by converting the monofixing near eye to distance vision and then using reading glasses for near work. Of the 12 patients, 7 regained their fusion by doing away with monovision and 5 required surgery to reestablish motor or sensory control. All of the surgery patients obtained an excellent alignment but 1 did not regain sensory fusion.

CONCLUSION

Monovision is successful for the far majority of patients who try it. However, in patients with a previous history of strabismus or those with significant phorias, caution should be used in recommending monovision, and if monovision is elected, keeping the anisometropia to small levels such as 1.25 to 1.50 diopters (D) might lessen the chance of producing strabismus post monovision. The majority of our patients developed strabismus after 2 years of monovision, telling us that while a trial of monovision with a contact lens prior to surgery may suggest that the patient could tolerate monovision, it is not a guarantee.

Refractive surgery: a treatment for and a cause of strabismus

PURPOSE OF REVIEW

The purpose of this article is to review refractive surgery as a means of treatment for strabismus and as a potential cause of strabismus and binocular diplopia.

RECENT FINDINGS

Numerous studies have reported that refractive surgery is effective in correcting certain types of strabismus such as accommodative and partially accommodative esotropia. Studies on the treatment of exotropia related to anisometropia have demonstrated less favorable outcomes. In patients without manifest strabismus preoperatively, recent studies have shown that strabismus and diplopia can occur after refractive surgery. Appropriate clinical testing and risk stratification are essential to determine whether a patient is at increased risk for postoperative strabismus and diplopia.

SUMMARY

Refractive surgery can be useful in patients with accommodative and partially accommodative esotropia. A thorough history and clinical examination is extremely important to expose potential risk factors in all patients undergoing refractive surgery. Based on the designated risk level, more advanced testing may be warranted.

Diplopia in adult patients following cataract extraction and refractive surgery

PURPOSE OF REVIEW

The purpose of this article is to report the incidence and cause of diplopia following cataract surgery and laser in-situ keratomileusis (LASIK).

RECENT FINDINGS

Ocular misalignment following cataract extraction with retrobulbar anesthesia has an incidence of approximately 7%. Diplopia ranges in this group of patients from 0.23 to 0.98%. The incidence of ocular misalignment decreases with topical anesthesia for cataract extraction to 5%, and diplopia occurs with an incidence of 0.21-0%. Although there are small case series, the incidence of diplopia following LASIK has not been reported. The causes of diplopia following cataract extraction and LASIK include decompensation of pre-existing strabismus, new-onset accommodative esotropia, concurrent onset of systemic disease, disruption of central fusion, and monocular diplopia. The leading cause for diplopia following retrobulbar anesthesia for cataract extraction is extraocular muscle paresis/restriction and is unique to this type of procedure. In cases of topical anesthesia for cataract extraction and for LASIK procedures, the leading cause of diplopia is decompensation of pre-existing strabismus.

SUMMARY

Detailed history and evaluation for pre-existing strabismus can dramatically decrease the incidence of unexpected diplopia following refractive procedures.

Refractive surgery in children

PURPOSE OF REVIEW

To evaluate recent literature regarding indications and outcomes for refractive surgery in children, including laser in-situ keratomileusis, laser epithelial keratomileusis, photorefractive keratectomy, and refractive intraocular lens placement.

RECENT FINDINGS

Refractive surgery in children is controversial. Recent publications have reported refractive surgery to treat strabismus and both ametropic and anisometropic amblyopia. Questions remain as to the age at which to perform the surgery, and which specific procedure to perform. Choice of technique depends on the clinical situation.

SUMMARY

Refractive surgery is an option for children with amblyopia and strabismus who fail treatment with spectacles or contact lenses. Prospective controlled studies are needed, and longer follow-up will answer questions about the utility and safety of refractive surgery in children.

Diplopia and strabismus following ocular surgeries

Postoperative diplopia and strabismus may result from a variety of ocular surgical procedures. Common underlying mechanisms include sensory disturbance, scarring, direct extraocular muscle injury, myotoxicity from injections of local anesthesia or antibiotics, and malpositioning of extraocular muscles by implant materials. The most common patterns are vertical and horizontal motility disturbance. Treatment options include prisms, botulinum, occlusion, or surgery.

Ocular dominance diagnosis and its influence in monovision

PURPOSE

To analyze the response of normal emmetropic subjects to different ocular dominance tests and to analyze the influence of this response in surgically induced monovision.

DESIGN

A prospective study of diagnostic accuracy was carried out to analyze the different tests to determine ocular dominance, without a gold standard test.

METHODS

Nine different tests were carried out in a group of 51 emmetropic subjects to determine both motor and sensory ocular dominance. For analysis, patients were divided into two groups according to age. Normal ophthalmologic examination results were the inclusion requirement, with normal binocular vision and good stereoacuity.

RESULTS

A significant percentage of uncertain or ambiguous results in all tests performed was found, except in the hole-in-card and kaleidoscope tests. When the tests were compared, two by two, the correlation or equivalence found was low and was much lower if tests were compared three by three.

CONCLUSIONS

No clear ocular dominance was found in most studied subjects; instead, there must be a constant alternating balance between both eyes in most emmetropic persons, but not in those with pathologic features. This fact would explain the great variability both between and within different kinds of tests. Also, it would establish that the monovision technique is well tolerated in most patients, with unsuccessful results only in those patients with strong or clear dominance. Consequently, it seems appropriate to evaluate patient's dominance before monovision surgery to exclude those individuals with clear dominance.

Binocular vision and refractive surgery

Binocular status can have an effect on the outcome of refractive surgery. Some accommodative deviations and anisometropia can be managed effectively. Fully accommodative esotropia has been successfully treated in young patients but the outcome can be less predictable in older patients. High anisometropes are usually unaffected by the change in aniseikonia following refractive surgery but there are exceptions. Failure to recognise and appropriately classify a binocular vision anomaly pre-surgically can result in symptoms that are difficult to manage post-operatively. Refractive surgery producing a binocular vision anomaly where there was none pre-operatively is less common. I present a review of the literature discussing the relationship between binocular vision anomalies and refractive surgery, illustrating the findings with published reports of successful and unsuccessful binocular postoperative outcomes. I argue that predicting the binocular outcome should be considered pre-operatively for every refractive surgery patient.

Comparison of aniseikonia as measured by the aniseikonia inspector and the space eikonometer

PURPOSE

The purpose of this study was to compare the new, computerized Aniseikonia Inspector with the Space Eikonometer for the measurement of aniseikonia.

METHODS

Eighteen subjects, ages 21 to 61 years, with normal binocular vision and normal visual acuity had aniseikonia measured with both the Aniseikonia Inspector Version I and the Space Eikonometer. Aniseikonia was measured first with the subjects' habitual refractive correction and then with afocal size lenses of 1%, 2%, and 3.5% added in random order before the right and left eyes. Measurements were taken initially with the Aniseikonia Inspector and on a subsequent day with the Space Eikonometer.

RESULTS

For the Space Eikonometer, the slopes of the lines for the relationship between the measured aniseikonia and the induced magnification differences in the vertical and horizontal meridians are not significantly different from 1.0. For the Aniseikonia Inspector, the slopes of the lines in the vertical and the horizontal meridians are less than and significantly different from 1.0. On average, the Aniseikonia Inspector underestimates the magnitude of induced aniseikonia, predicting only 68% and 61% of the overall size lens magnification in the vertical and horizontal meridians, respectively. The corresponding values of the Space Eikonometer in the vertical and horizontal meridians are 99% and 93%. Variability is greater with the Space Eikonometer than the Aniseikonia Inspector.

CONCLUSION

The Space Eikonometer appears to be measuring the induced aniseikonia appropriately, whereas the Aniseikonia Inspector underestimates the amount of aniseikonia. However, the Space Eikonometer shows greater measurement variability. Modification of the Aniseikonia Inspector or the testing conditions should be pursued in future studies.

Effect of refractive surgery on binocular vision and ocular alignment in patients with manifest or intermittent strabismus

OBJECTIVE

To evaluate the effect of refractive surgery on binocular vision and ocular alignment in patients with manifest or intermittent strabismus, with or without vertical component.

SETTING

University Hospital Antwerp, Edegem, Belgium.

PATIENTS AND METHODS

13 patients (22 eyes) with strabismus underwent refractive surgery. Five of these patients presented with an esotropia and four of them with a small vertical deviation. Five patients had a manifest exotropia, of whom two presented with a small vertical deviation. Two patients had an intermittent exotropia with binocular vision, of whom one patient had a vertical deviation. One patient had a hypertropia with a dissociated vertical deviation.

RESULTS

Ocular alignment and binocular function remained unchanged postoperatively in all except two patients with high anisometropia who experienced an improvement in binocular function. In these patients, the preoperative manifest deviation became intermittent or latent after surgery, allowing fusion and stereopsis. Vertical deviation was found preoperatively in 8 of the 13 patients. This vertical deviation remained unchanged postoperatively, but improved in one patient with anisometropia.

CONCLUSION

Preoperative intermittent or manifest strabismus is not a contraindication for refractive surgery provided some specific recommendations are taken into account, such as an adequate preoperative orthoptic examination and aiming at emmetropia for both eyes.

Refractive Surgery in Patients With High Myopic Anisometropia

PURPOSE

To assess the efficacy and safety of LASIK in patients with high myopic anisometropia and to provide specific screening guidelines for anisometropic patients undergoing refractive surgery.

METHODS

Twenty-six eyes of 16 patients with high myopic anisometropia (>3.0 diopters) were enrolled in this study. Complete pre- and postoperative ophthalmologic and orthoptic examinations were performed. The preoperative orthoptic examination was done with glasses and contact lenses. Twenty-two eyes of 13 patients underwent uncomplicated LASIK; the second eye was treated 2 weeks after the first eye. Patients were examined 1 day, 7 days, and 1, 3, 6, and 12 months after surgery.

RESULTS

Thirteen patients obtaining good results at red glass bar test (RGB) underwent LASIK without postoperative diplopia; four showed an improvement of the sensorial assessment. Three patients were excluded from surgery because of diplopia with RGB values <4 to 5. LASIK temporarily induced diplopia in the suppressed eye of one patient; however, the diplopia disappeared after surgery of the fixating eye.

CONCLUSIONS

Patients with high myopic anisometropia and a weak sensorial state who undergo refractive surgery may be at risk for postoperative diplopia. We suggest clinical guidelines to reduce the occurrence of this complication.

Unexpected outcomes associated with laser in situ keratomileusis: ptosis, anisocoria, and "curing" of exotropia

Laser in situ keratomileusis (LASIK) is a common and popular procedure that is generally associated with excellent results and few complications. We present 3 cases of unusual LASIK-related complications. In the first case, the patient developed anisocoria after otherwise unremarkable surgery. In the second case, the patient developed mild eyelid ptosis. In the third case, the patient's exotropia resolved after mild refractive overcorrection. In each case, the visual outcome was excellent and no further intervention was necessary.