INTRODUCTION
Strabismus is most commonly diagnosed in childhood, which is why most strabismus outpatient clinics focus on the pediatric population. However, the number of adult patients presenting with symptoms of ocular alignment disorders, such as diplopia or mechanical strabismus, constitutes a significant challenge in ophthalmic practice. The aim of this study was to analyze the reasons for adult patients presenting to the strabismus outpatient clinic at the University Clinical Center (UCK) of the Medical University of Warsaw (WUM), with particular emphasis on diagnoses according to the International Classification of Diseases (ICD-10) and the demographic characteristics of the study population.
MATERIAL AND METHODS
The medical records of consecutive patients presenting to the UCK WUM strabismus outpatient clinic were retrospectively reviewed. The analysis included 200 individuals over the age of 18 who attended the clinic between December 2023 and February 2024. Both first-time patients and individuals undergoing follow-up after previous surgical procedures or conservative treatment were included in the study group.
For each patient, demographic data (age, sex) and primary diagnoses according to the ICD-10 classification were analyzed. In accordance with the established protocol, a maximum of three diagnoses were recorded, prioritized according to their clinical significance. The analysis specifically distinguished mechanical strabismus, defined as restricted ocular motility resulting from extraocular muscle restriction (e.g., secondary to thyroid-associated orbitopathy or following orbital trauma), and paralytic strabismus, diagnosed in cases of weakness or loss of function in one of the muscles due to cranial nerve damage or other neurological causes.
Information regarding eligibility for surgical treatment was also recorded. The analysis involved data derived from routine medical records and did not contain patient- identifying information. For this reason, the study did not require approval from the Bioethics Committee.
RESULTS
In the analyzed group of 200 adult patients presenting to the UCK WUM strabismus outpatient clinic, the majority were female, and the mean age was higher among women than among men. Demographic data and the most frequently reported symptoms are summarized in Table 1.
Table 1
Demographic characteristics and most common symptoms reported by adult patients presenting to the strabismus outpatient clinic (N = 200)
The most common complaint directly leading to the visit was diplopia. It was reported by 45 patients (22.5%). Less frequently, patients reported difficulties with binocular vision, eye strain, or reduced vision of varying severity.
In terms of diagnoses, disorders of ocular alignment were predominant. Exotropia was the most frequent condition, followed by mechanical strabismus, which in a large proportion of cases was associated with thyroid-associated orbitopathy. Paralytic strabismus and esotropia were observed less frequently. The detailed distribution of diagnoses according to the ICD-10 classification is presented in Table 2.
Table 2
The most common ophthalmic diagnoses among patients of the strabismus outpatient clinic according to the International Classification of Diseases (ICD-10) (N = 200)
| ICD-10 code | Number of patients | Percentage (%) |
|---|---|---|
| H50.1 – exotropia (divergent concomitant strabismus) | 67 | 33.5 |
| H50.6 – mechanical strabismus | 54 | 27.0 |
| H06.2/E05 – dysthyroid exophthalmos | 53 | 26.5 |
| H53.2 – diplopia | 45 | 22.5 |
Additionally, two observations may have practical significance. First, the patient group included both first-time patients and those undergoing follow-up after prior treatment. However, comprehensive data regarding previous strabismus surgery were incomplete and were therefore excluded from statistical analysis. Second, no distinct differences were observed between men and women in the frequency of specific diagnoses, including mechanical strabismus, paralytic strabismus, or thyroid-associated orbitopathy.
A total of 65 individuals (32.5%) were considered eligible for surgical treatment. Most often, these were patients with significant diplopia or with mechanical ocular deviation that impaired binocular vision. In the majority of cases, eligibility for treatment depended on the etiology of the disorder, the duration of symptoms, and the stability of the strabismus angle.
DISCUSSION
Patients presenting to a strabismus outpatient clinic require a comprehensive ophthalmic evaluation, encompassing both clinical examination and the assessment of symptoms and comorbidities [1]. In adults, ocular misalignment is often secondary to systemic diseases or pre-existing binocular vision disorders. Consequently, accurate interpretation of symptoms requires clinical expertise and the appropriate selection of diagnostic methods [2]. Importantly, in some patients, strabismus may be the initial manifestation of a neurological disease, highlighting the need to distinguish between cases requiring urgent intervention and those suitable for out-patient management.
It is noteworthy that adult strabismus affects approximately 4% of the population and has a heterogeneous etiology [1]. A substantial proportion of cases originates in childhood and includes both concomitant and consecutive strabismus, even after previously successful therapy [3]. In the study group, exotropia was the most frequently observed diagnosis, which supports the notion that loss of fusion control in adulthood is a common reason for presentation to a strabismus outpatient clinic. This group of patients included both individuals with decompensated heterophoria and those with sensory disorders. Published data indicate that in adults with late-detected amblyopia, exotropia predominates, and the coexistence of a vertical deviation is not uncommon [4–7].
The second large group consisted of patients with mechanical strabismus, which was frequently secondary to thyroid-associated orbitopathy. Restrictive myopathy in the course of Graves’ disease affects up to half of patients with thyroid-associated orbitopathy and most commonly involves the inferior and medial rectus muscles [8, 9]. In this study group, thyroid-associated orbitopathy was one of the most frequent causes of ocular alignment disorders, underscoring the need for close collaboration between ophthalmologists and endo- crinologists, both during the diagnostic phase and subsequent patient management. In clinical practice, patients with thyroid conditions should be referred for ophthalmic consultation at an earlier stage, particularly when they present with retrobulbar pressure, eyelid edema, or initial episodes of diplopia.
In older adults, paralytic strabismus remains one of the most common causes of impaired ocular motility, associated with microvascular conditions, neurodegenerative changes, or vascular events [10]. In the diagnostic evaluation, it is important to differentiate this condition from divergence insufficiency, which also becomes more common with age and may be a cause of isolated diplopia, particularly at distance. This requires a thorough history and careful clinical examination, as symptoms may develop gradually [11–13].
Among patients included in this study, some presented with diplopia following orbital trauma or surgical procedures, which is consistent with reports indicating that ocular motility disorders occur in as many as 60–70% of patients after orbital fractures, and that surgical treatment may be necessary in selected cases [14, 15]. Strabismus has also been reported in the literature as a complication of sinus surgery and aesthetic procedures involving the orbital region [16–18].
In recent years, increasing attention has been paid to the importance of strabismus surgery in adults. The benefits of surgery extend beyond cosmetic correction and include improved binocular vision, reduced diplopia and compensatory head posture, expansion of the visual field, and decreased asthenopic symptoms [2]. Reports indicate that the success rate of the first surgery reaches 80%, with subsequent procedures achieving success rates of up to 95% [19–22]. The risk of new fusion disorders after surgery is low, making this approach both safe and predictable [20, 22–24]. At the same time, the psychosocial benefits of surgery are increasingly well documented, with patients reporting improvements in quality of life, self-confidence, and occupational functioning [25–30].
The results of this study confirm that ocular misalignment is a common reason for ophthalmic consultation among adults, and its etiology often requires a broad perspective that includes systemic diseases, particularly endocrine disorders. The presence of sensory strabismus further underscores the importance of early diagnosis of binocular vision disorders in childhood, as appropriate preventive measures may reduce the risk of strabismus manifesting only in adulthood.
CONCLUSIONS
In the analyzed group of adult patients presenting to the UCK WUM strabismus outpatient clinic, the mean age was 52 years, and the majority were women. Exotropia was the most frequently diagnosed disorder, while mechanical strabismus, largely due to thyroid-associated orbitopathy, constituted the second most common diagnostic category. Approximately one-third of the patients were scheduled for surgical treatment, highlighting the importance of both the functional and aesthetic aspects of procedures performed in this age group. The presence of sensory strabismus cases suggests that certain problems emerging only in adulthood may originate from binocular vision disorders that were already present in childhood. Early screening and appropriately conducted preventative care in children may reduce the number of adult patients requiring strabismus treatment.
