Decreasing strabismus surgery

Trends and patterns in pediatric ophthalmology and strabismus surgeries: a decade review from a leading Portuguese university hospital

PURPOSE

Strabismus and Pediatrics Ophthalmology surgeries are pivotal in addressing early-onset visual disorders. An 11-year retrospective study at a tertiary hospital center aimed to elucidate evolving surgical trends, focusing on esotropia cases.

METHODS

The surgical records from January 2009 to January 2020 were analyzed according to the baseline diagnosis. Esotropia cases were evaluated based on the patients' deviation types, surgical techniques, and pre-operative characteristics. A total of 2050 surgeries were performed over the study period.

RESULTS

Strabismus surgery accounts for 70% of the department's surgical activity. A trend toward a decrease in esotropia surgeries and a proportional increase in exotropia surgeries was noticeable. Esotropia cases, with a median surgical age of 6 years (p25-p75, 4-10) and uniform gender distribution (females, 54.8%), predominantly involved high angular deviations. Posterior fixation sutures emerged as the preferred surgical technique for esotropia.

CONCLUSION

The study's insights, while aligning with prior European research, introduce new dimensions to the understanding of strabismus surgeries, emphasizing the significance of early interventions, evolving surgical preferences, and the challenges posed by severe deviations.

The incidence, clinical features, and management of essential infantile esotropia in the United Kingdom. A British Ophthalmology Surveillance Unit (BOSU) study

BACKGROUND/OBJECTIVES

A national study was undertaken through the British ophthalmology surveillance unit (BOSU) to determine the incidence, presenting features and management of essential infantile esotropia (EIE) in the UK.

METHODS

Data from a prospective national observational study of newly diagnosed EIE presenting to clinicians in the United Kingdom over a 12-month period were collected. Cases with a confirmed diagnosis by a clinician of a constant, non-accommodative esotropia ≥20 prism dioptres (PD), presenting at ≤12 months, with no neurological or ocular abnormalities were identified through BOSU. Follow-up data were collected at 12 months.

RESULTS

A total of 57 cases were reported giving an incidence of EIE of 1 in 12,828 live births. The mean age of diagnosis and intervention were 7.05 ± 2.6 months (range 2-12) and 14.7 ± 4.9 months (range 6.5-28.1), respectively. Management was surgical in 59.6%, botulinum toxin alone in 22.8%, and 17.5% were observed. The preoperative angle of esotropia was smaller in the observation group (P = 0.04). The postoperative angle of esotropia was not statistically significant between botulinum toxin or surgery (P = 0.3), although the age of intervention was earlier in the botulinum group (P = 0.007). Early intervention (before 12 months of age) did not influence the post-intervention motor outcomes between 0 and 10 prism dioptres of esotropia (P = 0.78).

CONCLUSIONS

The incidence of EIE in the UK is considerably lower than reported in other population-based studies. The preferred method of treatment was surgical with earlier intervention in those treated with botulinum toxin. An early age of intervention (<12 months) did not influence motor outcomes.

[Change in the age spectrum in strabismus surgery]

BACKGROUND

The proportion of children undergoing strabismus surgery in the total volume of eye muscle operations appears to have decreased. To verify this we analyzed the age of patients who underwent extraocular muscle (EOM) surgery.

METHODS

The data of patients who underwent EOM surgery at the University Eye Hospital Giessen between 1991 and 2019 were reviewed and the numbers of operations in decadal age groups were compared to the German population in the respective period. In addition, the types of strabismus which led to surgery were evaluated. The data pool comprised > 25,000 surgeries involving > 60,000 muscles.

RESULTS

In comparison to 1991, in 2019 the proportion of children aged ≤ 10 years decreased from 50.2% to 31.8%, corresponding to a relative decrease of more than one third. The proportion of patients aged > 50 years increased from 6.5% to 22.5%, i.e., by a factor > 3, while the population ≤ 10 years in 2019 was 13% smaller than in 1991 and the population aged > 50 years increased by 37%. The major reason for the decreasing proportion of children was a 53% reduction in surgery for esotropia. We found no apparent changes in the 2nd-5th decades of life.

DISCUSSION AND CONCLUSION

The lower proportion of children undergoing EOM surgery appears to indicate an improvement in vision screening during the past 4 decades. The increasing proportion of older patients may result from better information on potential treatment and increased incidence of acquired strabismus with corresponding complaints. The demographic shift played a secondary role. Due to the population structure in Germany, a further increase in the demand for EOM surgery is to be expected.

Comitant strabismus etiology: extraocular muscle integrity and central nervous system involvement-a narrative review

Strabismus is not a condition in itself but the consequence of an underlying problem. Eye misalignment can be caused by disease, injury, and/or abnormalities in any of the structures and processes involved in visual perception and oculomotor control, from the extraocular muscles and their innervations to the oculomotor and visual processing areas in the brain. A small percentage of all strabismus cases are the consequence of well-described genetic syndromes, acquired insult, or disease affecting the extraocular muscles (EOMs) or their innervations. We will refer to them as strabismus of peripheral origin since their etiology lies in the peripheral nervous system. However, in most strabismus cases, that is comitant, non-restrictive, non-paralytic strabismus, the EOMs and their innervations function properly. These cases are not related to specific syndromes and their precise causes remain poorly understood. They are generally believed to be caused by deficits in the central neural pathways involved in visual perception and oculomotor control. Therefore, we will refer to them as central strabismus. The goal of this narrative review is to discuss the possible causes behind this particular type of eye misalignment and to raise awareness among eyecare professionals about the important role the central nervous system plays in strabismus etiology, and the subsequent implications regarding its treatment. A non-systematic search was conducted using PubMed, Medline, Cochrane, and Google Scholar databases with the keywords "origins," "causes," and "etiology" combined with "strabismus." A snowball approach was also used to find relevant references. In the following article, we will first describe EOM integrity in central strabismus; next, we will address numerous reasons that support the idea of central nervous system (CNS) involvement in the origin of the deviation, followed by listing several possible central causes of the ocular misalignment. Finally, we will discuss the implications CNS etiology has on strabismus treatment.

Ophthalmic surgery in New Zealand: analysis of 410,099 surgical procedures and nationwide surgical intervention rates from 2009 to 2018

BACKGROUND

Surgical intervention rates (SIR) provide a proxy measure of disease burden, surgical capacity, and the relative risk-benefit ratio of surgery. The current study assessed decade trends in ophthalmic surgery and calculated SIRs for all major classes of commonly performed ophthalmic procedures in New Zealand.

METHODS

Retrospective population-based analysis of all ophthalmic surgical procedures performed in New Zealand from 2009 to 2018. National and regional datasets from public and private health sectors and industry were analysed. SIRs were calculated for all major ophthalmic procedures, and subgrouped by patient demographics.

RESULTS

There were 410,099 ophthalmic surgical procedures completed with a 25.3% overall increase over 10 years. Procedures were mostly government-funded (51%, n = 210,830) with 71% of patients aged over 64 years. Cataract surgery (78%, n = 318,564) had the highest mean SIR (703/100,000/year) and increased by 25% during the study period, consistent with population growth in the over 64 years old age group. Vitrectomy surgery had the second highest mean SIR (67/100,000/year) and increased by 50%, well above national population growth during the study period. Other SIRs included conjunctival lesion-biopsy (38/100,000/year), glaucoma (33/100,000/year), strabismus (20/100,000/year), dacryocystorhinostomy (10/100,000/year), and keratoplasty surgery (4/100,000/year).

CONCLUSIONS

This comprehensive review of New Zealand ophthalmic surgery reports increasing SIRs that cannot be explained by population growth alone. Cataract surgery numbers increased year on year consistent with the increase in the over 64 years old population. Vitrectomy surgery growth exceeded that of the national population, including those over 64 years.

Characteristics and differences of strabismus surgeries performed in private versus public settings: a national multicenter study

PURPOSE

To investigate and compare the demographics, diagnoses, and surgical procedure types of strabismus repair in public and private hospitals in Israel in order to highlight possible disparities between them.

METHODS

Retrospective descriptive study included all strabismus surgeries in seven private hospitals, compared with two large public university-affiliated hospitals from June 2016 to June 2021. Electronic medical records were directly retrieved to produce an anonymized database.

RESULTS

During the study period 2420 operations were performed. Patients who underwent strabismus surgery in public hospitals were older and had shorter procedures (p < 0.001 and p = 0.004, respectively). The median number of operated muscles and the prevalence of bilateral procedures were higher in private hospitals (p < 0.001 and p < 0.001, respectively). Surgery for common strabismus, especially esotropia, was more prevalent in private (p < 0.001), whereas surgery for vertical strabismus, cranial nerve palsies and complex syndromes were performed more often in public hospitals (p < 0.001, p = 0.008, and p < 0.001, respectively). Rectus recession and inferior oblique (IO) anteriorization were more predominant in private hospitals (p = 0.002 and p < 0.001, respectively), while recuts advancement and IO myectomies were more prevalent in public ones (p = 0.001 and p < 0.001, respectively). Reoperations were far more common in public hospitals (27.2% vs 6.2%, p < 0.0001). This was true across most age groups.

CONCLUSIONS

Candidates for strabismus surgery in private hospitals in Israel are often younger, with more common diagnoses, and are usually referred for simpler procedures.

A retrospective study of strabismus surgery in a tertiary eye hospital in the Chaoshan area in China from 2014 to 2020

BACKGROUND

To investigate the distribution pattern of strabismus surgery at an eye center in southern China.

METHODS

The data of all patients who underwent strabismus surgery at the Joint Shantou International Eye Center of Shantou University /Chinese University of Hong Kong from 2014 to 2020 were retrospectively analyzed. The type of strabismus and its relationship with age and sex were analyzed, and the trend in the number of strabismus surgeries was observed.

RESULTS

The data of 4640 patients included a total of 5,282 surgeries. Exotropia surgery was the most common, accounting for 54.0% of all strabismus surgeries, which tended to increase over time, but not significantly (P = 0.109). Constant exotropia was the most common exotropia, but its proportion decreased year by year. The next most common was intermittent exotropia. The percentage of surgeries for intermittent exotropia increased from 2016 to 2020. Surgery for esotropia accounted for 22.1% of all strabismus surgeries and became significantly less common from 2016 to 2020 (P < 0.01). Among patients with intermittent or constant exotropia, the proportion of patients younger than 12 years who underwent surgical intervention increased yearly, while this proportion amoung patients older 12 years old with constant exotropia decreased yearly.

CONCLUSION

Among exotropia surgeries, surgery for constant exotropia was the most common but decreased in prevalence annually. Children under 12 years old were the most affected population.

Characteristics and long-term surgical outcomes of horizontal strabismus

PURPOSE

Our aim was to report the characteristics and long-term surgical outcomes of three subgroups of horizontal strabismus in a single institution (divided by strabismus subtype) in a developing country and look into pre-operative factors predictive of surgical success.

METHODS

Two hundred and forty-four complete charts of patients, divided into 152 esotropes (ET) and 92 exotropes (XT) who had undergone horizontal strabismus surgeries, were retrospectively reviewed. Charts of patients with muscle palsy, Duane syndrome and consecutive strabismus were excluded; 172 patients were included divided into partially accommodative ET, congenital ET and intermittent XT. Surgical success was defined as a post-operative angle deviation of 12 prism diopters or less.

RESULTS

The mean follow-up period of all patients was 31.64 ± 23.12 months. The subgroups were divided into partially accommodative ET (60 patients), congenital ET (60 patients), and intermittent XT (52 patients). Esotropes (both partially accommodative and congenital) presented earlier (p < 0.001). Also, partially accommodative ET had a significantly higher spherical equivalent (SE) compared to congenital ET patients, who had a higher SE than intermittent XT (p < 0.001). Congenital ET patients had a significantly larger angle of deviation (for both far and near) than both partially accommodative ET and intermittent XT patients (p < 0.001). The overall success rate was 72.67% for the whole group with no significant differences among subgroups. Success rate of partially accommodative ET surgery was 78.33% compared to that of congenital ET at 66.67% and intermittent XT at 73.07%. Significant post-operative improvement in sensory fusion was observed mainly for patients with partially accommodative esotropia and intermittent exotropia.

CONCLUSION

Our results showed that esotropes (both partially accommodative and congenital) presented earlier, with a higher spherical equivalent in the partially accommodative ET subgroup, while the congenital ET subgroup had the largest angle of deviation for both distance and near. The overall surgical success rate for horizontal strabismus surgery was 72.67% with the 3 subgroups having similar success rates. A younger age at presentation and absence of amblyopia were positively correlated with surgical success in the partially accommodative esotropia group.

Endophthalmitis after strabismus surgery: incidence and outcome in relation to age, operated eye muscle, surgical technique, scleral perforation and immune state

PURPOSE

Identify risk factors for endophthalmitis after strabismus surgery (EASS) and relate these to incidence and outcome.

METHODS

Ophthalmologists, who had operated, diagnosed or treated EASS, completed a case record form with 71 questions in six domains: Preoperative, Surgery, Perforation, Postoperative, Outcome and Experts' opinion. To estimate the age-specific incidence per number of strabismus operations in the Netherlands during 1994-2013, the age distribution of Dutch cases was compared with the age-specific rates of strabismus surgery in the Dutch Registry of Strabismus Operations and with population data. Exploratory data analysis was performed. The immune state was evaluated in six patients. Five enucleated eyes were studied histopathologically.

RESULTS

None of the 26 patients (27 eyes with EASS) were between 9 and 65 years old, except for one patient with retinal haemorrhage followed by endophthalmitis. In the Netherlands during 1994-2013, the rate of EASS was approximately one per 11 000 strabismus operations, but one per 4300 for children aged 0-3 and one per 1000 for patients 65 and older. Endophthalmitis was diagnosed on postoperative day 1-4 in children aged 0-3. In all 15 children aged 0-5, the 16 affected eyes were phthisical, eviscerated or enucleated. The involved eye muscle had been recessed in 25 of 27 cases. It was a medial rectus in 15 of 16 children aged 0-6. It was a lateral (6), inferior (2) or medial (1) rectus in elderly. Scleral perforation went unnoticed in all children (no record in three) and in two of seven elderly (no record in two). Histopathology showed transscleral scarring compatible with scleral perforation in four patients but, in a two-year-old girl who had EASS together with a transient medial rectus palsy, the sclera underneath the former suture tract was not perforated but did contain the long posterior ciliary artery.

CONCLUSIONS

Endophthalmitis after strabismus surgery (EASS) affects children and elderly, with a grave outcome in young children. It occurs after recession of the medial rectus muscle in children, and it may occur without scleral perforation. Age and perforation are key determinants that interact with other factors that determine the occurrence and fulminance of EASS.

Current trends of strabismus surgery in a tertiary hospital

OBJECTIVE

To analyze the strabismus surgeries and the outcomes during a year and a half in a tertiary hospital.

MATERIAL AND METHODS

A retrospective study of patients who underwent strabismus surgery. The mean age, sex, diagnosis, diplopia, surgery, anesthesia, adjustable sutures, results, reoperations and follow up time from surgery were analyzed. A good outcome was considered when the final horizontal deviation was less than 10prism diopters (pd) and the vertical deviation less than 5pd without diplopia.

RESULTS

A total of 153 cases were operated on, mean age: 43.14 ±25.58years (61.4%: women). 74.5% of patients were ≥18years (33.33% ≥60). Diplopia was present in 51% of patients. The most frequent deviation was horizontal: 83.6%. The most frequent diagnosis was cranial nerve palsies: 32% (VI nerve: 12.4%), restrictive strabismus: 7.2%, and the aged related distance esotropia: 6.5%. Adjustable sutures were used in 19.7% of cases and topical anesthesia in 65.4%. Good outcomes was present in 79.2% of cases at the end of follow-up. Reoperations were needed in 25.5%. Follow-up evolution time was 11.87 months ±6.5. The sex female (P=.012) and the oblique superior surgery (P=.017) were associated with bad outcome.

CONCLUSION

The adult strabismus surgery was three times more frequent than the children strabismus surgery. The third of the adults that were operated on were ≥60 years. The cranial nerve palsies were the most frequent diagnosis. Adjustable sutures were rarely used. Good outcomes were obtained in most of the patients at the end of follow-up.

The Danish Rural Eye Study: prevalence of strabismus among 3785 Danish adults - a population-based cross-sectional study

PURPOSE

To determine the prevalence of strabismus among Danish adults and to find the frequency of history of strabismus and strabismus surgery. Furthermore, to evaluate the prevalence of strabismus-associated amblyopia among participants with strabismus and to relate the results to the current national vision screening programme.

METHODS

In total, 3785 adults in the Danish Rural Eye Study underwent an interview regarding eye health, visual acuity measurement, Hirschberg test and retinal photography. Participants were categorized into groups based on their birth date in relation to the introduction of the national vision screening programme.

RESULTS

In total, the prevalence of strabismus was 1.1% (41/3785; 95% CI: 0.8-1.5); no differences were found in relation to gender or screening status. The prevalence of exotropia (XT) was 0.3% (12/3785; 95% CI: 0.2-0.6) and of esotropia (ET) 0.8% (29/3785; 95% CI: 0.5-1.1), resulting in an XT:ET ratio of 1:2.7. A history of strabismus was present in 4.6% (174/3785; 95% CI: 4.0-5.3), and a history of strabismus surgery was present in 0.8% (32/3785; 95% CI: 0.6-1.2) of the participants. Among participants with manifest strabismus, 24% had strabismus-associated amblyopia.

CONCLUSION

In this first European population-based study of strabismus prevalence in adults, the prevalence was similar to three out of five previous studies using cover test. The use of Hirschberg test may have led to an underestimation of the true prevalence. The prevalence was neither related to screening status nor gender. Our results are the first to display a predominance of ET among Caucasian Scandinavian adults.

Intermediate filaments in the medial rectus muscles in patients with concomitant exotropia

PURPOSE

Distribution of intermediate filament (IF) proteins in normal extraocular muscles (EOMs) showed that the EOMs differ significantly from the other muscles in the body with respect to their IFs composition, including desmin and nestin. The aim of the present study was to investigate the pathological changes in the medial rectus (MR) in patients with concomitant exotropia (XT).

METHODS

Forty-six MR muscle samples from 46 patients with XT were analyzed pathologically and processed for immunohistochemistry with specific antibodies against desmin and nestin.

RESULTS

Although most of MR muscles remained normal structures relatively, they presented high expression of desmin, and in contrast, nestin was absent in a large proportion of the MR muscles.

CONCLUSION

Desmin, which is downregulated in normal EOMs, had high expression in MR muscles of patients with XT. Nestin, which is present in a high proportion of normal EOMs, was downregulated in MR muscles of patients with XT.

Botulinum toxin chemodenervation for childhood strabismus in England: National and local patterns of practice

Background

Botulinum toxin injection chemodenervation is a well-established intervention for adult strabismus, and has also been recognised as an effective alternative to routine incisional surgery for paediatric disease. We aimed to investigate the temporal patterns of practice, indications and outcomes of chemodenervation for paediatric strabismus at national and tertiary centre level.

Methods

Retrospective study using routinely collected patient data: Hospital Episode Statistics (HES) data were used to identify children undergoing non-incisional strabismus procedures in England from 2007 to 2016. Single–centre retrospective data on children undergoing botulinum toxin injections (Dysport^® 2.5 units/ 0.1ml) as an isolated intervention (not involving incisional procedures) was undertaken to identify indications and outcomes. Successful outcome was defined as deviation <11 prism dioptres (PD).

Results

Between 2007 and 2016, there was no increase in the proportion of childhood strabismus involving non-incisional procedures. Amongst 150 children undergoing chemodenervation for strabismus within the tertiary centre, the most common diagnoses were acute onset esotropia (n = 34), infantile esotropia (n = 16) and consecutive exotropia (n = 15). Median age at injection was 8.5 years (range 0.9–15 years), and median follow up 12 months (6 months—11 years). Success rates differed by diagnosis, from 66% (non or partially accommodative esotropia) to 0% (congenital cranial disorders). Adverse events were seen in 62/150, 41%, most commonly transient ptosis (39%, n = 58). Overcorrection was seen in 14/119, 13%. Mild subconjunctival haemorrhage (n = 2) was the only other adverse event.

Conclusions

Botulinum toxin for childhood strabismus has an acceptable safety profile, and considerable potential therapeutic benefit. However, nationally there has been no increased uptake of chemodenervation non-incisional procedures. Further prospective studies are necessary to understand the predictors of outcome within the separate clinical subgroups, to guide clinical decision making.

Changing Strabismus Surgery Distribution at Shanxi Province Eye Hospital in Central China

PURPOSE

To investigate whether there has been a changing trend of strabismus surgery in a provincial eye hospital in the central part of China over the past decade.

METHODS

This was a retrospective analysis of data on all strabismus surgery performed in Shanxi Province Eye Hospital in China during the past 10 years. Recorded characteristics included patient demographics, type of strabismus, age, and gender.

RESULTS

A total of 12,327 patients received strabismus surgery in the eye hospital from 2005 to 2014. The number of surgeries increased steadily from 800 in 2005 to 1,723 in 2014 (P < .01). Constant exotropia was the most common type among all types of strabismus. Superior oblique muscle palsy was the most common type of paralytic strabismus. Exotropia oblique A- and V-pattern type was the most common type of special strabismus.

CONCLUSIONS

The amount of strabismus surgery increased during the past decade. The proportion of patients with intermittent exotropia increased over time compared to those with other types of strabismus. [J Pediatr Ophthalmol Strabismus. 2017;54(2):112-116.].

Childhood amblyopia: current management and new trends

INTRODUCTION OR BACKGROUND

With a prevalence of 2-5%, amblyopia is the most common vision deficit in children in the UK and the second most common cause of functional low vision in children in low-income countries.

SOURCES OF DATA

Pubmed, Cochrane library and clinical trial registries (clinicaltrials.gov, ISRCTN, UKCRN portfolio database).

AREAS OF AGREEMENT

Screening and treatment at the age of 4-5 years are cost efficient and clinically effective. Optical treatment (glasses) alone can improve visual acuity, with residual amblyopia treated by part-time occlusion or pharmacological blurring of the better-seeing eye. Treatment after the end of the conventional 'critical period' can improve vision, but in strabismic amblyopia carries a low risk of double vision.

AREAS OF CONTROVERSY

It is not clear whether earlier vision screening would be cost efficient and associated with better outcomes. Optimization of treatment by individualized patching regimes or early start of occlusion, and novel binocular treatment approaches may enhance adherence to treatment, provide better outcomes and shorten treatment duration.

GROWING POINTS

Binocular treatments for amblyopia.

AREAS TIMELY FOR DEVELOPING RESEARCH

Impact of amblyopia on education and quality of life; optimal screening timing and tests; optimal administration of conventional treatments; development of child-friendly, effective and safe binocular treatments.

Exotropia Is the Main Pattern of Childhood Strabismus Surgery in the South of China: A Six-Year Clinical Review

Purpose. To evaluate the distribution pattern and changes of strabismus surgery in children based on the data collected from a local eye hospital in the south of China between 2006 and 2011. Methods. A retrospective analysis of all strabismus surgeries in children (<18 years) performed in the Eye Hospital of Wenzhou Medical University between 2006 and 2011 using the integrated information system. Result. A total of 2,219 strabismus surgeries were performed during the study period, with concomitant exotropia (44% of all surgeries) more than esotropia (27%, χ² = 42.7, p < 0.001). Total number of surgeries increased from 250 in 2006 to 508 in 2011, with a significant increase in concomitant exotropia: 38% of all surgeries in 2006 increased to 47% in 2011 (χ² = 29.4, p < 0.001). The increase of intermittent exotropia was approximately 26% of all increments of strabismus surgery between 2006 and 2011. Conclusion. Surgery for childhood exotropia was more frequent than esotropia in China. The proportion of exotropia progressively increased, while the proportion of esotropia decreased during these years. Intermittent exotropia was the main increment of strabismus surgery. Further population-based studies are needed to confirm the proportion of surgery and whether the incidence of strabismus surgery increased in China.

Comitant strabismus: Perspectives, present and future

Comitant strabismus is a common condition affecting infants, children and adults. Its impact on the affected patient may be severe resulting in visual loss, lack of binocularity, diplopia, social stigma and multiple corrective surgeries within the affected individual's lifespan. It is therefore important that this prevalent disorder should be better understood. We review the current understanding of the demographics and what is known of the etiology, risk factors and genetics of strabismus. We stress the importance of careful clinical assessment in classifying strabismus, and the common pitfalls in the measurement and pre-operative sensory work-up of the strabismic patient. The fact strabismus is comitant does not indicate it is benign: acute onset of comitant esotropia may be a presenting sign of pontine or cerebellar tumor. Lastly, we review the impact of genetics on our understanding of strabismus. While the causes of many types of congenital incomitant strabismus have been elucidated through careful observation and genetic screening, the genetics of comitant strabismus are more complex and multifactorial. Only through careful study and recruitment of large groups of affected individuals and families can we start to answer the question: why is this group of patients pre-disposed to develop strabismus. Doing so will help identify patients at risk, to spare them from the significant morbidity associated with this common disorder.

Time trends over five decades, and recent geographical variation, in rates of childhood squint surgery in England

AIMS

To study trends in rates of childhood squint surgery in England over five decades, and to study recent geographical variation in England.

METHODS

Use of routine hospital statistics to analyse trends in squint surgery in the Oxford record linkage study area 1963-2010, and England 1968-2010; analysis of geographical variation in England 1999-2010. All rates, numerators and population denominators were restricted to people aged under 15 years.

RESULTS

The study included 519 089 admissions for operations on squint. Annual admission rates for squint surgery in England fell from 188.8 episodes per 100 000 population (95% CI 180.9 to 196.8) in 1968 to 64.1 (62.4 to 65.7) episodes per 100 000 population in 2010. A similar decline was seen in the Oxford region, from 213.2 (181.3 to 245.2) episodes per 100 000 population in 1963 to 61.3 (54.8 to 67.9) episodes in 2010. There was wide variation across local authorities in annual rates of squint surgery from 28.2 (95% CI 22.7 to 34.8) admissions per 100 000 population to 138.6 (123.0 to 155.7) admissions per 100 000, a 4.9-fold difference between areas with the highest and lowest rates.

CONCLUSIONS

Squint surgery rates have decreased substantially over time. The current wide geographical variation in rates raises questions about whether this scale of variation is clinically warranted, whether it reflects variation in needs for surgery and patient/parental choice, whether it is a result of inequalities in the availability of ophthalmic services, or whether it results from variation between clinicians in clinical decision making about the likely benefits of squint surgery.

Abnormal expression of seven myogenesis-related genes in extraocular muscles of patients with concomitant strabismus

Hyperplasia or hypoplasia of muscles gradually leads to strabismus. Myogenesis-related genes are involved in extraocular muscle development, including myogenic differentiation 1 (MYOD1), myogenin (MYOG), retinoblastoma 1 (RB1), cyclin-dependent kinase inhibitor 1A (P21), cyclin‑dependent kinase inhibitor 1C (P57), insulin-like growth factor 1 (IGF1) and muscle creatine kinase (MCK). This study evaluated the expression of the above seven myogenesis-related genes by real-time quantitative RT-PCR in 18 resected extrocular muscles of patients with concomitant strabismus and 12 normal control muscle samples from one presumably healthy male 6 h after sudden mortality. We found that although there was a great divergence among the expression levels of 6 myogenesis-related regulatory factors, the relative expression patterns were similar in all the normal muscles, including the synergistic, antagonistic and yoke muscles. However, their expression levels in the 18 diseased extraocular muscles were abnormal; the expression levels of all the genes, with the exception of P57, were reduced in most of the diseased muscle tissues. These results imply that the abnormal expression of these myogenesis-related genes may contribute to concomitant strabismus.

Trends in surgical correction of strabismus: a 20-year experience, 1990-2009

BACKGROUND

Recent reports and anecdotal observations suggest that strabismus surgery, particularly for infantile esotropia, may be in decline, although a recent population-based study found the incidence to be stable.

METHODS

We analyzed the surgical database of 4,494 primary pediatric strabismus procedures from 1990 through 2009 at Children's Medical Center of Dallas. Linear regression models were used to identify the relationship between the year and the proportion of each surgical category (infantile esotropia, all esotropia, exotropia, and other) using the least-squares approach.

RESULTS

Surgery for infantile esotropia (mean age, 10 months) was performed on 374 patients (mean, 19; range, 11-27/year). Trend analysis demonstrated no significant change in the annual rate of surgery for infantile esotropia (R(2) = 0.004) during the 20-year study period. Additionally, when compared to the annual number of births in Dallas County, no significant change in the incidence of surgically corrected infantile esotropia was noted during the study period (P = 0.25); however, surgery for both infantile esotropia (P = 0.001) and for any esotropia (P = 0.002) declined, while surgery for exotropia increased (P = 0.002) as a proportion of all primary strabismus surgeries.

CONCLUSIONS

The incidence of surgically corrected infantile esotropia has remained stable over a 20-year period. As a proportion of all primary strabismus procedures, surgery for all types of esotropia has decreased and for exotropia has increased.

A 4 year retrospective survey of strabismus surgery in Tongren Eye Centre Beijing

PURPOSE

To investigate the distribution pattern of the strabismus surgery undertaken at an eye centre in Beijing, China.

METHODS

A retrospective analysis was conducted including the data of all strabismus surgeries performed in Beijing Tongren hospital for the 4 year period from 2003 to 2006. The proportions of different surgery types and their association with patients' age and gender were analyzed.

RESULT

During the study period, 8997 strabismus surgeries were performed. The number of the surgeries increased progressively each year from 1507 in 2003 to 2769 in 2006 (p < 0.05). Intermittent exotropia was the most common of all strabismus surgeries (27.9%). Superior oblique palsy was the most common type among the paralytic strabismus surgeries. The proportions of different types of strabismus showed no significant change between successive years. Among the patients, the number of surgeries performed in the population aged 0-12 years was significantly higher than other age groups and increased from 35.37% in 2003 to 42.80% in 2006 (p < 0.05).

CONCLUSION

There has been a continuous increase in the number of strabismus operations in our eye centre in Beijing, and this pattern is especially obvious in children. The distribution of surgery type remained relatively constant each year. Surgery for intermittent exotropia is the most common type of procedure.

Outcome of monocular surgery for horizontal strabismus in Hyderabad

BACKGROUND AND OBJECTIVE

Squint surgery is frequently performed successfully in Hyderabad. However, no study in any detail has been performed on the outcome of monocular surgery for horizontal squint in the region. This study aims to determine the results of monocular surgery for horizontal trabismus.

DESIGN

Retrospective/observational study.

SUBJECTS AND METHODS

The study was conducted on patients aged under 45 years, presenting with horizontal strabismus and undergoing monocular squint surgery. Anterior segment slit lamp examination, and if possible, posterior segment examination with 90 diopter (D) and 78 D fundoscopes was performed. Angle of deviation was measured. Patients were divided into two groups (esotropia and exotropia). Investigations were performed. Surgery was done under general anesthesia. A second surgical procedure was performed after six months for any residual deviations.

RESULTS

After squint surgery, patients in group 1 (79%) and in group 2 (73.3%) had residual deviation of less than 15 prism diopters (PD). The preoperative deviations of 60 PD or less illustrated excellent domino effects with residual deviation of fewer than 15 PD. Three patients with successive deviation underwent a second surgery with excellent outcomes.

CONCLUSION

Few extraocular muscles can be prevented due to monocular squint surgery when multiple surgeries are needed.

Is the incidence of infantile esotropia declining?: a population-based study from Olmsted County, Minnesota, 1965 to 1994

OBJECTIVE

To investigate the incidence of infantile esotropia from a defined population in the United States over a 30-year period. Recent reports from the United Kingdom have suggested that strabismus or strabismus surgery is occurring less frequently today than in previous years.

METHODS

The medical records of all patients diagnosed with infantile esotropia within Olmsted County, Minnesota, from January 1, 1965, through December 31, 1994, were retrospectively reviewed.

RESULTS

The birth prevalence of infantile esotropia during the 30-year period was 25 (95% confidence interval, 21-29) per 10 000, or 1 in 403 live births. Although there were slightly more cases of infantile esotropia in the earlier years (45 from 1965-1974, 51 from 1975-1984, and 34 from 1985-1994), the change in incidence over time was not statistically significant (P = .32). The mean number of surgeries performed on each patient in this cohort was similar during the 30-year study: 1.8 for those diagnosed from 1965 to 1974, 1.9 for 1975 to 1984, and 1.6 for 1985 to 1994.

CONCLUSIONS

The incidence of infantile esotropia in this population has not significantly changed from 1965 through 1994. Moreover, the rate of surgical intervention over these years is similar for this patient population.

Nationwide study of hospitalization and surgical treatment for childhood strabismus in Italy between 1999 and 2004

Surgery for strabismus is in decline in countries like the United Kingdom. The aim of the present study was to determine whether this trend is also present in Italy and, also, to ascertain the number of squint operations performed in a six-year period. A retrospective review of all discharge summaries and procedures performed (diagnostic and therapeutic) for strabismus in Italian children aged 0-14 years old in the period 1999-2004 was undertaken. The total number of surgical procedures was 21,204. The number (per 10,000) was 4.24 in 1999, 4.33 in 2000, 4.31 in 2001, 4.25 in 2002, 4.23 in 2003, and 4.05 in 2004. The figure for 2004 was reduced by 4.48% with respect to 1999 and by 6.46% with respect to 2000. Temporal analysis revealed that the total number of single-muscle procedures remained stable for the first two years and then decreased in 2001 and 2002, and, above all, in 2003 and 2004. No significant change was noted in the number of procedures involving two or more muscles. It is also noteworthy that very few operations for strabismus were performed on children less than one year of age. The trend revealed by our data cannot be compared to the overall reduction in strabismus surgery that has been observed in England and Ontario, but there was a moderate decrease in the frequency of single-muscle surgical procedures among Italian children aged 0-14 years old in 2003 and 2004. Further investigation is needed to determine how this trend has evolved since 2004.

Rates of strabismus surgery in the United States: implications for manpower needs in pediatric ophthalmology

PURPOSE

To investigate rates of strabismus surgery and population projections in the United States and to consider whether a sufficient number of pediatric ophthalmologists are being trained to meet future needs.

METHODS

Review of online data from Series 13 reports from the National Center for Health Statistics for the period 1965 to 1996, including reports from the National Hospital Discharge Survey and the National Survey of Ambulatory Surgery. Population data were obtained from the U.S. Census Bureau.

RESULTS

The current rate of strabismus surgery for children under 15 years of age is 80 per 100,000 persons in the United States. This rate would generate an additional 389 strabismus cases annually, based on the predicted growth of the pediatric population. On average, today's pediatric ophthalmologist performs about 114 strabismus procedures annually.

CONCLUSIONS

If the current rates and trends remain stable over the coming years, it is not likely that there will be a shortage of pediatric ophthalmologists in the United States.

Sleep does not enhance the recovery of deprived eye responses in developing visual cortex

Monocular deprivation (MD) during a critical period of visual development triggers a rapid remodeling of cortical responses in favor of the open eye. We have previously shown that this process is enhanced by sleep and is inhibited when the sleeping cortex is reversibly inactivated. A related but distinct form of cortical plasticity is evoked when the originally deprived eye (ODE) is reopened, and the non-deprived eye is closed during the critical period (reverse monocular deprivation (RMD)). Recent studies suggest that different mechanisms regulate the initial loss of deprived eye responses following MD and the recovery of deprived eye responses following RMD. In this study we investigated whether sleep also enhances RMD plasticity in critical period cats. Using polysomnography combined with microelectrode recordings and intrinsic signal optical imaging in visual cortex we show that sleep does not enhance the recovery of ODE responses following RMD. These findings add to the growing evidence that different forms of plasticity in vivo are regulated by distinct mechanisms and that sleep has divergent roles upon different types of experience-dependent cortical plasticity.