Abstract
Purpose
To characterize the diagnostic spectrum of a tertiary neuro-ophthalmology service in Thailand and to describe the etiologic distribution of selected H47-coded optic nerve and optic disc records after chart-based adjudication.
Patients and Methods
We conducted a retrospective service-based study of outpatient (OPD) and inpatient (IPD) neuro-ophthalmic records from January 2015 through December 2025. Analyses distinguished unique individuals, setting-specific patient-year records, patient-year-category records, and individual diagnostic records. H46-coded optic neuritis records were retained as code-based diagnoses; selected H47-coded records underwent manual chart adjudication by a fellowship-trained neuro-ophthalmologist using prespecified criteria. Annual analyses combined OPD and IPD after same-person/same-year cross-setting deduplication.
Results
The dataset contained 1533 OPD and 504 IPD setting-specific patient-year records, representing 1815 unique individuals overall and 1905 cross-setting patient-years. Optic nerve and optic disc disorders occurred in 769/1,533 OPD patient-years (50.2%; 95% CI, 47.7–52.7) and 302/504 IPD patient-years (59.9%; 95% CI, 55.6–64.1). At the diagnostic-record level, 1076 optic nerve/disc records were identified: 344 H46-coded optic neuritis records and 732 selected H47-coded records with chart-based final classification. The most frequent diagnostic records were optic neuritis (344, 32.0%), optic atrophy/optic neuropathy NOS (230, 21.4%), ischemic optic neuropathy (111, 10.3%), optic disc cupping/glaucoma suspect (102, 9.5%), traumatic optic neuropathy (94, 8.7%), and compressive optic neuropathy (76, 7.1%). Optic nerve/disc disorders were the numerically largest category in every study year, accounting for 47.2%–58.3% of annual cross-setting patient-years.
Conclusion
In this single-center service-based dataset, optic nerve and optic disc diagnoses were the most frequently recorded neuro-ophthalmic category. Manual chart review of selected H47-coded records enabled more detailed etiologic grouping, while H46-coded optic neuritis remained a code-based subgroup. The findings describe local tertiary referral practice and should be externally validated before generalizing the classification approach across institutions.
Keywords: neuro-ophthalmology, optic neuropathy, optic neuritis, chart adjudication, service-based epidemiology
Plain Language Summary
Neuro-ophthalmology deals with vision problems caused by disorders of the optic nerve, eye movements, pupils, and visual pathways. We reviewed 11 years of records from a tertiary neuro-ophthalmology service in Thailand to understand which problems were most often recorded in outpatient and inpatient care. We counted the data at several levels to handle repeat years, multiple diagnoses, and patients seen in both settings consistently.
We found that optic nerve and optic disc disorders were the largest diagnostic group throughout the study period. For selected records coded within the H47 group, a neuro-ophthalmologist reviewed the charts and assigned more specific clinical categories. Records coded as H46 optic neuritis were kept as code-based optic neuritis and were not re-adjudicated. These results describe the case mix of one tertiary referral service and can help guide future studies using clearly defined counting rules and independently validated diagnostic methods.
Introduction
Neuro-ophthalmic disorders encompass diseases affecting the optic nerve, optic disc, visual pathways, ocular motor system, and pupillary function. These disorders may present with visual loss, visual-field defects, diplopia, abnormal ocular motility, or pupillary abnormalities and may represent either vision-threatening ophthalmic disease or serious underlying neurological conditions. Consequently, neuro-ophthalmology services frequently manage diagnostically complex patients requiring neuroimaging, laboratory investigations, multidisciplinary evaluation, and longitudinal follow-up.1–3
Understanding the distribution of neuro-ophthalmic disorders is important for characterizing clinical workload, referral patterns, diagnostic complexity, and healthcare resource requirements. Previous service-based studies from different regions have shown that optic nerve disorders, ocular motor disorders, and visual complaints constitute substantial components of neuro-ophthalmic practice; however, their relative frequencies vary considerably by referral pathways, healthcare systems, study populations, and diagnostic definitions.2–7 Longitudinal data are particularly valuable because referral and diagnostic patterns may also change over time.4 Nevertheless, many previous studies have examined relatively short observation periods, individual clinical settings, or broad diagnostic categories, limiting understanding of the long-term spectrum of neuro-ophthalmic practice.
Among neuro-ophthalmic conditions, optic nerve and optic disc disorders are particularly heterogeneous. Administrative diagnostic codes may encompass diseases with substantially different etiologies, diagnostic pathways, prognoses, and management strategies.8–10 Reliance on administrative coding alone may therefore provide limited insight into the underlying clinical spectrum of these disorders. Detailed chart review of selected heterogeneous diagnostic categories can provide more clinically meaningful etiologic classification and complement service-level analyses based on routinely collected diagnostic data.11,12
In Southeast Asia, and particularly in Thailand, long-term data describing neuro-ophthalmic practice remain limited. Previous Thai and regional studies have provided important information regarding the distribution of neuro-ophthalmic diseases, but have generally involved shorter observation periods or different service populations.2,5,7 Comprehensive analyses spanning both outpatient and inpatient care over an extended period remain scarce. These settings may represent different aspects of neuro-ophthalmic practice: outpatient services commonly manage chronic or subacute disorders and longitudinal follow-up, whereas inpatient consultations may disproportionately involve acute visual loss, diplopia, papilledema, and neurological conditions requiring urgent investigation or multidisciplinary management.6,9,10 Characterizing both settings may therefore provide a more complete picture of neuro-ophthalmic service utilization.
Our previous study at the same institution described pediatric visual disorders using functional visual complaint codes (H53–H54).13 The present study addresses a distinct clinical question by examining the broader neuro-ophthalmic spectrum across all age groups, evaluating both outpatient and inpatient activity, and incorporating chart-based etiologic classification of selected heterogeneous optic nerve and optic disc records. Thus, although the two studies originate from the same institution and partly overlap in calendar periods, their populations, diagnostic frameworks, and study objectives differ.
Accordingly, this study aimed to characterize the diagnostic spectrum of outpatient and inpatient neuro-ophthalmic practice at a tertiary referral center over an 11-year period, describe annual diagnostic patterns using explicitly defined patient-year denominators, and further characterize the etiologic spectrum of selected optic nerve and optic disc disorders through clinical chart review.
Patients and Methods
Study Design and Setting
This retrospective observational service-based study was conducted at the Neuro-Ophthalmology Service, Division of Ophthalmology, Phramongkutklao Hospital, Royal Thai Army Medical Department, Bangkok, Thailand. Electronic diagnostic records from OPD and IPD care dated 1 January 2015 through 31 December 2025 were included in the source extraction.
Study Population, Diagnostic Codes, and Exclusions
The prespecified major categories were: optic nerve and optic disc disorders (H46 and selected H47 records: H47.0, H47.2, H47.3, and H47.6), papilledema (H47.1), ocular motor disorders (H49.0–H49.4 and H49.8–H49.9 as present in the dataset), visual disturbance/visual-field disorders (H53.2 and H53.4), and pupil abnormalities (H57.0). Isolated H02.4 and H50.x records were excluded, as were ophthalmic codes outside these five prespecified groups.
Eight source records carried H47.6, a code that is not itself specific for optic nerve/disc disease in standard ICD-10 classification. These records were not treated as optic nerve/disc disease solely because of the administrative code; they were retained only because the pre-existing manual chart review had assigned a final optic nerve/disc diagnosis. This exception is stated explicitly to avoid implying that H47.6 is an optic-nerve-specific code.
Units of Analysis and Counting Rules
We defined a unique individual as one hospital identifier across the full study period. A setting-specific patient-year was one individual within one calendar year and one care setting. A cross-setting patient-year was one individual within one calendar year after combining OPD and IPD and removing same-person/same-year overlap. A patient-year-category record was one individual-year within one major diagnostic category; repeated rows from the same category within the same year were counted once for category-level analyses. An individual diagnostic record was one qualifying diagnostic row and was used to describe the etiologic distribution of optic nerve and optic disc disorders.
Patients seen in multiple years contributed one patient-year in each year. A patient seen in both OPD and IPD in the same year contributed to each setting-specific analysis but only once to the cross-setting annual denominator. Distinct diagnoses within the same year could contribute to multiple categories. The source extraction did not contain visit identifiers or eye laterality; therefore, encounter-level and eye-level analyses were not performed. Bilateral or recurrent disease did not generate separate eye-level counts.
Chart Adjudication of Selected H47-Coded Records
Selected H47-coded records (H47.0, H47.2, H47.3, and the eight H47.6 records described above) underwent manual chart review by a fellowship-trained neuro-ophthalmologist. The review used clinical history, neuro-ophthalmic examination, visual function testing, ophthalmic ancillary investigations, neuroimaging, laboratory investigations, electrophysiology (when available), and longitudinal follow-up. Established neuro-ophthalmology references informed the operational diagnostic criteria and evidence hierarchy, which are provided in Supplementary Table S1.11,12,14
H46-coded records were retained as code-based optic neuritis and were not subjected to the same chart-based etiologic adjudication. Accordingly, the manuscript does not describe the entire set of 1076 optic nerve/disc diagnostic records as clinically adjudicated. A single fellowship-trained neuro-ophthalmologist performed adjudication; no independent inter-reviewer reliability sample was available, and this is acknowledged as a limitation.
Data Completeness and Cohort Construction
The source files contained 3421 OPD and 698 IPD diagnostic rows. After exclusion of rows outside the five prespecified categories, 1533 OPD and 521 IPD qualifying diagnostic rows remained. The OPD qualifying rows represented 1533 patient-years; the 521 IPD rows represented 515 patient-year-category records and 504 patient-years. Age, sex, year, ICD-10 code, and major category were complete for all final patient-year records; a chart-derived final category was present for all 732 selected H47-coded diagnostic records. Imaging, laboratory testing, electrophysiology, and follow-up were not structured analytic fields in the supplied datasets, and their missingness therefore could not be quantified from these files. Supplementary Figure S1 summarizes record construction.
Outcome Measures
The outcomes were the frequency and proportion of major diagnostic categories by care setting, the etiologic distribution of optic nerve/disc diagnostic records, and descriptive annual category frequencies and proportions after cross-setting same-person/same-year deduplication.
Statistical Analysis
Revised calculations and consistency checks were performed in Python 3.13.5. Continuous variables are reported as mean ± standard deviation or median with interquartile range. Categorical variables are reported as n (%). For major diagnostic category distributions by care setting, the denominator for each category proportion was the number of setting-specific patient-years (OPD n=1,533; IPD n=504), and Wilson 95% confidence intervals were calculated for descriptive purposes at the setting-specific patient-year level. These intervals treat patient-year observations as independent and do not account for within-person correlation arising from repeated observations across calendar years; they should therefore be interpreted as descriptive record-level intervals rather than person-level inferential estimates. For the etiologic distribution of optic nerve/disc disorders, percentages were calculated using optic nerve/disc diagnostic records as denominators (OPD n=769; IPD n=307; total n=1,076). For annual cross-setting analyses, the denominator for each year was the number of unique patient-years in that year after same-person/same-year deduplication across OPD and IPD. No inferential OPD–IPD comparison or formal temporal trend test was performed; annual changes are therefore described as descriptive patterns rather than statistical trends.
Ethical Considerations
This study adhered to the Declaration of Helsinki and was approved by the Royal Thai Army Medical Department Institutional Review Board (Approval No. S010h/69_Exp). The requirement for informed consent was waived because of the retrospective design and use of de-identified routinely collected clinical data. Hospital numbers have been removed from the revised shared analytic dataset and replaced by randomly generated study identifiers.
Results
Cohort and Patient Characteristics
The final setting-specific analyses included 1533 OPD patient-years and 504 IPD patient-years. These represented 1533 unique OPD individuals and 470 unique IPD individuals; 188 individuals appeared in both settings, for a total of 1815 unique individuals. At the patient-year level, 132 same-person/same-year records occurred in both OPD and IPD, so 2037 setting-specific patient-years corresponded to 1905 cross-setting unique patient-years. Table 1 shows demographic characteristics.
Table 1.
Demographic Characteristics According to Care Setting
| Variable | OPD (n=1533 Patient-years) |
IPD (n=504 Patient-years) |
|---|---|---|
| Age, mean ± SD (years) | 52.2 ± 20.3 | 50.8 ± 20.3 |
| Median age (IQR), years | 55 (37–67) | 53 (36–66) |
| Male, n (%) | 884 (57.7) | 248 (49.2) |
| Female, n (%) | 649 (42.3) | 256 (50.8) |
Notes: Demographic values use setting-specific patient-year records. Age, sex, year, and ICD-10 code were complete in the final analytic patient-year dataset.
Abbreviations: IQR, interquartile range; IPD, inpatient department; OPD, outpatient department; SD, standard deviation.
Major Diagnostic Categories
Optic nerve and optic disc disorders were recorded in 769/1,533 OPD patient-years (50.2%; 95% CI, 47.7–52.7) and 302/504 IPD patient-years (59.9%; 95% CI, 55.6–64.1). Visual disturbance/visual-field disorders occurred in 26.5% of OPD patient-years, whereas ocular motor disorders occurred in 25.8% of IPD patient-years (Table 2). Because a patient-year could contribute to more than one major category, category percentages are not mutually exclusive.
Table 2.
Frequency of Major Neuro-Ophthalmic Diagnostic Categories According to Care Setting
| Diagnostic Category | OPD n (%); 95% CI N=1533 Patient-years |
IPD n (%); 95% CI N=504 Patient-years |
|---|---|---|
| Optic nerve and optic disc disorders | 769 (50.2); 47.7–52.7 | 302 (59.9); 55.6–64.1 |
| Visual disturbance / visual field disorders | 407 (26.5); 24.4–28.8 | 52 (10.3); 8.0–13.3 |
| Ocular motor disorders | 280 (18.3); 16.4–20.3 | 130 (25.8); 22.2–29.8 |
| Papilledema | 67 (4.4); 3.5–5.5 | 14 (2.8); 1.7–4.6 |
| Pupil abnormalities | 10 (0.7); 0.4–1.2 | 17 (3.4); 2.1–5.3 |
Notes: Numerators are unique setting-specific patient-year-category records. Denominators are all setting-specific patient-years. A patient-year could contribute to more than one diagnostic category; therefore, percentages are not mutually exclusive and may sum to more than 100%. Only selected H47-coded optic nerve/disc records underwent chart adjudication. The 95% confidence intervals are descriptive Wilson intervals calculated at the patient-year level and do not account for within-person correlation from repeated observations across years.
Etiologic Distribution of Optic Nerve and Optic Disc Diagnostic Records
At the diagnostic-record level, 1076 optic nerve/disc records were identified: 769 OPD and 307 IPD. These comprised 344 H46-coded optic neuritis records and 732 selected H47-coded records with chart-derived final categories. The difference between the 302 IPD optic patient-year-category records in Table 2 and the 307 IPD optic diagnostic records in Table 3 is explained by five IPD patient-years that contained two distinct optic nerve/disc diagnostic rows. Thus, the values reflect different prespecified units rather than conflicting totals.
Table 3.
Etiologic Distribution of Optic Nerve and Optic Disc Diagnostic Records
| Diagnosis | OPD n (%) | IPD n (%) | Total n (%) |
|---|---|---|---|
| Optic neuritis (H46) | 167 (21.7) | 177 (57.7) | 344 (32.0) |
| Optic atrophy/optic neuropathy, NOS | 197 (25.6) | 33 (10.7) | 230 (21.4) |
| Ischemic optic neuropathy | 103 (13.4) | 8 (2.6) | 111 (10.3) |
| Optic disc cupping/ glaucoma suspect | 56 (7.3) | 46 (15.0) | 102 (9.5) |
| Traumatic optic neuropathy | 87 (11.3) | 7 (2.3) | 94 (8.7) |
| Compressive optic neuropathy | 60 (7.8) | 16 (5.2) | 76 (7.1) |
| Others/unclear | 29 (3.8) | 12 (3.9) | 41 (3.8) |
| Congenital optic disc anomaly | 18 (2.3) | 6 (2.0) | 24 (2.2) |
| Optic disc edema, NOS | 20 (2.6) | 1 (0.3) | 21 (2.0) |
| Toxic/nutritional optic neuropathy | 21 (2.7) | 0 (0.0) | 21 (2.0) |
| Hereditary/genetic optic neuropathy | 9 (1.2) | 0 (0.0) | 9 (0.8) |
| Optic disc drusen/ pseudopapilledema | 2 (0.3) | 1 (0.3) | 3 (0.3) |
| Total | 769 (100.0) | 307 (100.0) | 1076 (100.0) |
Notes: Table 3 uses individual diagnostic records, not patient-year-category records. H46-coded optic neuritis was retained as a code-based subgroup and was not chart-adjudicated. The remaining 732 selected H47-coded records were assigned chart-derived final categories. Five IPD patient-years contained two distinct optic nerve/disc diagnostic records, explaining the difference between 302 IPD optic patient-year-category records in Table 2 and 307 IPD optic diagnostic records here. Papilledema (H47.1) was analyzed separately.
Optic neuritis was the most frequent diagnostic record (344, 32.0%), followed by optic atrophy/optic neuropathy NOS (230, 21.4%), ischemic optic neuropathy (111, 10.3%), optic disc cupping/glaucoma suspect (102, 9.5%), traumatic optic neuropathy (94, 8.7%), and compressive optic neuropathy (76, 7.1%) (Table 3; Figure 1). Optic neuritis accounted for 57.7% of IPD optic diagnostic records vs 21.7% of OPD optic diagnostic records. Compressive optic neuropathy accounted for 5.2% of IPD and 7.8% of OPD optic diagnostic records and was therefore not proportionally greater in IPD.
Figure 1.
Etiologic distribution of optic nerve and optic disc diagnostic records. Horizontal bar chart showing the etiologic distribution of 1076 optic nerve and optic disc diagnostic records identified during the study period. H46-coded optic neuritis records were retained as a code-based subgroup and were not subjected to the chart-adjudication process used for selected H47-coded records. The remaining selected H47-coded records were assigned final etiologic categories following manual chart review using predefined criteria. Percentages were calculated using all 1076 optic nerve and optic disc diagnostic records as the denominator. The horizontal axis represents the number of diagnostic records, not the number of unique patients.
Abbreviations: H46, ICD-10 code for optic neuritis; H47, ICD-10 category encompassing selected optic nerve and optic disc disorders; ICD-10, International Classification of Diseases, Tenth Revision; NOS, not otherwise specified.
Descriptive Annual Patterns
After OPD–IPD same-person/same-year deduplication, annual cross-setting patient-year denominators ranged from 120 to 220. Optic nerve/disc disorders were numerically the largest major category in every year, accounting for 47.2%–58.3% of annual patient-years (Table 4; Figure 2). Annual category counts and proportions fluctuated across the study period. Because no formal trend analysis was performed, these patterns are not interpreted as evidence of temporal stability or change. The higher service volume around 2020 is described descriptively and cannot be attributed to the COVID-19 period from these data alone.
Table 4.
Annual Frequency and Proportion of Major Neuro-Ophthalmic Diagnostic Categories After OPD–IPD Cross-Setting Deduplication
| Year | Optic Nerve/Disc n (%) |
Ocular Motor n (%) |
Visual Disturbance/Field n (%) |
Papilledema n (%) |
Pupil Abnormalities n (%) |
Annual Patient-Years |
|---|---|---|---|---|---|---|
| 2015 | 90 (50.8) | 31 (17.5) | 43 (24.3) | 12 (6.8) | 3 (1.7) | 177 |
| 2016 | 73 (50.3) | 27 (18.6) | 40 (27.6) | 6 (4.1) | 0 (0.0) | 145 |
| 2017 | 64 (49.6) | 26 (20.2) | 32 (24.8) | 4 (3.1) | 5 (3.9) | 129 |
| 2018 | 59 (49.2) | 25 (20.8) | 29 (24.2) | 8 (6.7) | 1 (0.8) | 120 |
| 2019 | 77 (51.7) | 43 (28.9) | 25 (16.8) | 5 (3.4) | 3 (2.0) | 149 |
| 2020 | 124 (56.4) | 49 (22.3) | 35 (15.9) | 9 (4.1) | 4 (1.8) | 220 |
| 2021 | 103 (51.0) | 43 (21.3) | 47 (23.3) | 9 (4.5) | 2 (1.0) | 202 |
| 2022 | 94 (51.6) | 39 (21.4) | 43 (23.6) | 6 (3.3) | 1 (0.5) | 182 |
| 2023 | 94 (47.2) | 35 (17.6) | 60 (30.2) | 8 (4.0) | 3 (1.5) | 199 |
| 2024 | 85 (47.8) | 40 (22.5) | 45 (25.3) | 7 (3.9) | 2 (1.1) | 178 |
| 2025 | 119 (58.3) | 27 (13.2) | 51 (25.0) | 5 (2.5) | 3 (1.5) | 204 |
Notes: For each year, OPD and IPD were combined and the same individual in the same calendar year was counted once in the annual denominator. Category numerators are unique patient-year-category records after cross-setting deduplication. Because a patient-year may contribute to more than one category, percentages are not mutually exclusive. These values are descriptive annual patterns; no formal temporal trend test was performed.
Figure 2.
Annual proportions of major neuro-ophthalmic diagnostic categories, 2015–2025. Line graph showing the annual proportions of the five major neuro-ophthalmic diagnostic categories from 2015 through 2025. For each calendar year, outpatient and inpatient records were combined, and the same individual appearing in both settings during the same year was counted once in the annual denominator. Category numerators represent unique patient-year-category records after cross-setting deduplication. Because one patient-year could contribute to more than one diagnostic category, category proportions were not mutually exclusive, and their sum could exceed 100%. Different marker shapes were used to distinguish diagnostic categories, while all connecting lines were displayed as solid lines. The figure presents descriptive annual proportions only and does not represent a formal statistical test of temporal trend.
Abbreviations: IPD, inpatient department; OPD, outpatient department.
Discussion
This 11-year service-based study shows that optic nerve and optic disc disorders constituted the largest major diagnostic category in both OPD and IPD neuro-ophthalmic practice at this Thai tertiary referral center. This overall pattern is broadly consistent with service-based studies from other tertiary neuro-ophthalmology settings, in which optic nerve disorders, ocular motor disorders, and visual complaints constitute substantial proportions of referrals, although the exact distribution varies by referral system and study definition.1–7 The revised analysis also clarifies that the combined optic nerve/disc spectrum contains two verification levels: H46-coded optic neuritis retained from administrative coding and selected H47-coded records assigned more specific categories after chart review.
The particularly high proportion of optic neuritis among IPD optic diagnostic records is clinically plausible for a tertiary referral service because acute inflammatory optic neuropathies may require urgent neurologic evaluation, neuroimaging, laboratory investigation, and systemic treatment.6,8 This interpretation is contextual rather than causal because the analytic files did not include referral-source and acuity variables.
Traumatic optic neuropathy represented 11.3% of OPD optic diagnostic records and 2.3% of IPD optic diagnostic records. The hospital’s military and tertiary referral role may contribute to this pattern, but the available data do not permit attribution to military status or specific referral sources; referral populations influence the diagnostic spectrum observed in tertiary neuro-ophthalmology services.1,4–6 Similarly, glaucoma-suspect/cupping records were included only when patients entered the neuro-ophthalmology service because of diagnostic uncertainty regarding nonglaucomatous optic neuropathy. Because distinguishing glaucomatous from nonglaucomatous optic neuropathy may require integration of optic-disc appearance, visual fields, retinal nerve fiber layer findings, neuroimaging, and the broader clinical context, these records should be interpreted as referral-workload diagnoses rather than as a population estimate of glaucoma.11,12,14
Optic atrophy/optic neuropathy NOS remained a substantial group (21.4%), and an additional 3.8% were classified as others/unclear. In clinical neuro-ophthalmology, etiologic classification of optic neuropathy often depends on synthesis of history, examination, visual function, imaging, laboratory data, and longitudinal evolution rather than a single definitive test.11,12,14 Accordingly, interpret these residual categories as unresolved diagnostic uncertainty in retrospective practice rather than evidence that chart adjudication improved diagnostic accuracy. The present study did not compare adjudicated diagnoses with an independent reference standard or measure inter-reviewer agreement.
Annual proportions are presented to contextualize raw counts with changing service volume. Previous service-based studies show that neuro-ophthalmology referral patterns can vary by institutional role, referral pathways, and time period.1,4–6 Optic nerve/disc disorders were numerically predominant each year in our dataset, but we intentionally avoid describing the case mix as statistically stable because repeated individuals, changes in referral pathways, coding practices, staffing, record completeness, and the COVID-19 period could influence observed annual patterns.
The study has several strengths. It covers 11 years of both OPD and IPD activity, uses explicit counting rules that distinguish patient-years from diagnostic records, and provides chart-derived etiologic grouping for selected H47-coded records. The clinical classification approach was anchored to established neuro-ophthalmic diagnostic principles rather than administrative coding alone.11,12,14 The revised de-identified analytic dataset includes the final analytic category and a data dictionary, allowing reproduction of the reported descriptive counts.
Several limitations warrant emphasis. First, this is a single-center tertiary referral dataset and does not estimate population incidence or prevalence; tertiary service-based series are intrinsically shaped by referral patterns and institutional roles.1–7 Second, repeated patient-years and OPD–IPD overlap reflect service activity; although these observations were deduplicated according to each prespecified analysis, repeated patient-years from the same individual are not statistically independent. Accordingly, the Wilson confidence intervals presented for setting-specific proportions are descriptive patient-year-level intervals and do not account for within-person correlation. Third, one neuro-ophthalmologist adjudicated charts without an independent reliability sample. Fourth, H46 optic neuritis was retained without re-adjudication and therefore remains susceptible to administrative-code misclassification. Fifth, the source data did not include visit identifiers, eye laterality, or structured completeness indicators for imaging, laboratory investigations, electrophysiology, or follow-up. Sixth, referral pathways, staffing, coding practices, and record completeness may have changed over 11 years, including during the COVID-19 period.4 Finally, the substantial NOS and unclear categories reflect residual uncertainty inherent in retrospective documentation and the multifactorial diagnostic process used in neuro-ophthalmology.11,12,14
These findings may help describe the workload encountered in comparable tertiary services and may inform the design of future multicenter registries.1,3,4,6 Future work should use harmonized case definitions grounded in established neuro-ophthalmic diagnostic principles, independent adjudication, and external validation before a classification framework is considered reproducible across institutions.11,12,14
Conclusion
In this single-center service-based dataset, optic nerve and optic disc diagnoses were the most frequently recorded neuro-ophthalmic category among included patient-years. Manual chart review of selected H47-coded records permitted more detailed etiologic grouping, whereas H46-coded optic neuritis remained a code-based subgroup. The findings reflect local tertiary referral practice and require independent validation before the classification approach can be generalized across institutions.
Acknowledgments
The authors thank Dr. Thitiporn Ratanapojnart, Chief Director of the Ophthalmology Department at Phramongkutklao Hospital, for institutional support and guidance.
Funding Statement
There is no funding to report.
Data Sharing Statement
A de-identified analytic dataset containing randomly generated study identifiers, the variables used for the reported analyses, the final analytic category, a data dictionary, and the prespecified counting rules is provided with the revised submission. (Supplementary Table S2) The shared file does not include the HN-to-study-ID linkage.
Author Contributions
All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.
Disclosure
The authors report no conflicts of interest in this work.
References
- 1.Stunkel L, Mackay DD, Bruce BB, Newman NJ, Biousse V. Referral patterns in neuro-ophthalmology. J Neuroophthalmol. 2020;40(4):485–10. doi: 10.1097/WNO.0000000000000846 [DOI] [PubMed] [Google Scholar]
- 2.Rai BB, Sarac O, van Kleef JP, Maddess T. Incidence and pattern of neuro-ophthalmological disorders presenting to vitreoretinal clinics in Bhutan: a 3-year national study. Clin Ophthalmol. 2023;17:107–114. doi: 10.2147/OPTH.S396879 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Simao LM, de Almeida ACV, Viana MTSA, et al. The patient’s clinical profile from a neuro-ophthalmology center in Brazil: a retrospective study. J Neuroophthalmol. 2024;44(4):e520–e525. doi: 10.1097/WNO.0000000000002057 [DOI] [PubMed] [Google Scholar]
- 4.Belson OD, Avisar N, Huna-Baron R. Referral pattern changes over a decade in a tertiary neuro-ophthalmology clinic. Clin Ophthalmol. 2026;20:597432. doi: 10.2147/OPTH.S597432 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Mekhasingharak N, Koohasawad S, Chirapapaisan N. Neuro-ophthalmic diseases in a tertiary hospital in Thailand: a prospective study. Thai J Ophthalmol. 2019;33(2):92–100. [Google Scholar]
- 6.Okrent Smolar AL, Ray HJ, Dattilo M, et al. Neuro-ophthalmology emergency department and inpatient consultations at a large academic referral center. Ophthalmology. 2023;130(12):1304–1312. doi: 10.1016/j.ophtha.2023.07.028 [DOI] [PubMed] [Google Scholar]
- 7.Lim SA, Wong WL, Fu E, et al. The incidence of neuro-ophthalmic diseases in Singapore: a prospective study in public hospitals. Ophthalmic Epidemiol. 2009;16(2):65–73. doi: 10.1080/09286580902737516 [DOI] [PubMed] [Google Scholar]
- 8.Bennett JL. Optic neuritis. Continuum. 2019;25(5):1236–1264. doi: 10.1212/CON.0000000000000768 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Wall M. Idiopathic intracranial hypertension. Neurol Clin. 2010;28(3):593–617. doi: 10.1016/j.ncl.2010.03.003 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Maheswaran M, Dheera MS, Kumar M, Kowsalya A. Pediatric papilledema at a tertiary care ophthalmological center. Indian Pediatr. 2020;57(10):966–967. PMID: 33089814. doi: 10.1007/s13312-020-2006-4 [DOI] [PubMed] [Google Scholar]
- 11.Biousse V, Newman NJ, Micieli JA, eds. Neuro-Ophthalmology Illustrated. 3rd ed. Stuttgart, Germany: Georg Thieme Verlag; 2020. doi: 10.1055/b-006-163723 [DOI] [Google Scholar]
- 12.Smith S, Lee AG, Brazis PW. Clinical Pathways in Neuro-Ophthalmology: An Evidence-Based Approach. 3rd ed. Stuttgart, Germany: Thieme; 2019. [Google Scholar]
- 13.Srimanan W, Keokajee P. Spectrum of pediatric visual disorders in outpatient and inpatient settings at a tertiary hospital: a 10-year retrospective study. Clin Ophthalmol. 2026;20:596742. doi: 10.2147/OPTH.S596742 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Miller NR, Subramanian PS, Patel VR, eds. Walsh and Hoyt’s Clinical Neuro-Ophthalmology: The Essentials. 4th ed. Philadelphia, PA: Wolters Kluwer; 2021. [Google Scholar]
Associated Data
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Data Availability Statement
A de-identified analytic dataset containing randomly generated study identifiers, the variables used for the reported analyses, the final analytic category, a data dictionary, and the prespecified counting rules is provided with the revised submission. (Supplementary Table S2) The shared file does not include the HN-to-study-ID linkage.