Ultra-High Resolution Optical Coherence Tomography for Differentiation of Ocular Surface Squamous Neoplasia and Pterygia

It Is All About the Angle: A Clinical and Optical Coherence Tomography Comparison of Corneal Ocular Surface Squamous Neoplasia and Corneal Pannus

PURPOSE

The aim of this study was to compare clinical characteristics and high-resolution optical coherence tomography (HR-OCT) findings between corneal ocular surface squamous neoplasia (OSSN) and corneal pannus.

METHODS

Retrospective study of 9 individuals, 3 with lesions histologically confirmed to be OSSN, 3 with lesions histologically confirmed to be pannus, 1 with lesions histologically confirmed to be OSSN followed by pannus, and 2 with long-standing, nonchanging lesions clinically diagnosed as pannus. All individuals presented to the Miami Veterans Affairs Medical Center eye clinic or Bascom Palmer Eye Institute between 2015 and 2023. Clinical characteristics and HR-OCT findings were evaluated and compared.

RESULTS

Mean age of the population was 72.8 ± 5.1 years, 100% self-identified as male, 100% as White, and 11.1% as Hispanic. Clinically, all lesions appeared as whitish, opalescent, variably vascularized opacities extending from the limbus. None of the OSSN cases had vessels that extended to the border, whereas 4 cases of pannus (67%) had at least 1 vessel that reached the border. On HR-OCT, epithelial hyperreflectivity was observed in all cases of OSSN and pannus. Epithelial thickening was observed in all cases of OSSN, but in none of the cases of pannus. An important distinction between the 2 groups was the transition between normal and abnormal epithelium. All cases of OSSN had a vertical transition, whereas all cases of pannus had an angled transition.

CONCLUSIONS

Corneal OSSN and corneal pannus can both present with clinical findings of an opalescent lesion and may have overlapping findings on HR-OCT. Although both entities may show epithelial hyperreflectivity on HR-OCT, OSSN demonstrates an abrupt transition at a vertical, 90 degrees angle perpendicular to the Bowman layer, whereas pannus appears as an angled transition around 45 degrees. Therefore, the angle of transition between normal and abnormal epithelium can be useful in distinguishing between the 2 entities.

Conjunctival keratoacanthoma: a clinical and histopathological case series

OBJECTIVE

To present a series of conjunctival keratoacanthomas and provide clinical, histopathological, immunohistochemical, and imaging results that characterize this rare entity.

METHODS

A retrospective chart review of records from 2005 to 2023 from the Florida Lions Ocular Pathology Laboratory was conducted. Nine patients with histologically proven conjunctival keratoacanthoma were identified. Data extracted includes demographics, clinical history, diagnostic testing, histopathological and immunohistochemical testing, treatment modalities, and recurrences.

RESULTS

Patients' mean age was 55.2 ± 21.1 years (range: 22-83). 77.8% (7/9) of patients were male. 55.6% (5/9) were Hispanic. 55.6% of lesions (5/9) were in right eyes. 55.6% of lesions (5/9) were on the temporal, bulbar conjunctiva. The lesions were rapidly growing, with mean onset time of 4.71 ± 3.30 weeks (range: 2-12). High-resolution anterior segment optical coherence tomography of three lesions revealed hyper-reflective, thickened epithelium with abrupt transition between normal and abnormal epithelium. Underlying disorganized subepithelial tissue was noted. However, the overlying abnormal epithelium caused considerable shadowing, which obscured subepithelial structures. Prominent, keratin-filled, cup-shaped lesions with faulty maturational sequencing that extend full thickness, variably pale cytoplasm, and foci of dyskeratosis and hyperkeratosis were present on all lesions' histopathology. All lesions were surgically excised, but two demonstrated partial spontaneous resolution before surgery. Two patients were lost to follow-up; the remaining seven had no signs of recurrence at a of mean of 36.9 ± 45.4 months (range: 3 to 141 months) of follow-up.

CONCLUSIONS

Conjunctival keratoacanthomas are rare lesions of the ocular surface with distinct clinical, histopathologic, and diagnostic features.

Can high-resolution optical coherence tomography provide an optical biopsy for ocular surface lesions?

High-resolution optical coherence tomography (HR-OCT) has transformed the diagnosis and management of ocular surface lesions. Providing a detailed cross-sectional view of the cornea and conjunctiva, HR-OCT can be used to identify characteristic features of various benign and malignant ocular surface lesions, aiding in their diagnosis and guiding treatment. When incorporated into an ophthalmology clinic, HR-OCT provides morphological images of lesions in a noninvasive means, akin to an "optical biopsy". The characteristic HR-OCT features of several lesions have been well described in the literature, including for ocular surface squamous neoplasia, papilloma, melanoma, primary acquired melanosis, complexion associated melanosis, nevus, pterygium, pinguecula, lymphoma, and amyloidosis. HR-OCT can be used to differentiate between lesions with similar clinical features, lesions that co-exist on the same ocular surface, and atypically presenting lesions, such as pigmented ocular surface squamous neoplasia or amelanotic melanoma. The management of ocular surface lesions has been transformed by the implementation of HR-OCT, providing clinicians with the ability to monitor tumor response to topical chemotherapies, follow previously excised lesions for recurrence, and map out tumor borders intraoperatively. While there are some limitations to HR-OCT, including imaging of thick or deep lesions, it has become an essential tool for ocular oncologists in the management of ocular surface lesions.

Novel automated non-invasive detection of ocular surface squamous neoplasia using artificial intelligence

Ocular surface squamous neoplasia (OSSN) is a common eye surface tumour, characterized by the growth of abnormal cells on the ocular surface. OSSN includes invasive squamous cell carcinoma (SCC), in which tumour cells penetrate the basement membrane and infiltrate the stroma, as well as non-invasive conjunctival intraepithelial neoplasia, dysplasia, and SCC in-situ thereby presenting a challenge in early detection and diagnosis. Early identification and precise demarcation of the OSSN border leads to straightforward and curative treatments, such as topical medicines, whereas advanced invasive lesions may need orbital exenteration, which carries a risk of death. Artificial intelligence (AI) has emerged as a promising tool in the field of eye care and holds potential for its application in OSSN management. AI algorithms trained on large datasets can analyze ocular surface images to identify suspicious lesions associated with OSSN, aiding ophthalmologists in early detection and diagnosis. AI can also track and monitor lesion progression over time, providing objective measurements to guide treatment decisions. Furthermore, AI can assist in treatment planning by offering personalized recommendations based on patient data and predicting the treatment response. This manuscript highlights the role of AI in OSSN, specifically focusing on its contributions in early detection and diagnosis, assessment of lesion progression, treatment planning, telemedicine and remote monitoring, and research and data analysis.

Comparison of non-invasive diagnostic modalities for ocular surface squamous neoplasia at a tertiary hospital, South Africa

AIMS

The aim of the study is to assess non-invasive diagnostic modalities for ocular surface squamous neoplasia (OSSN) when compared to histology.

METHODS

A prospective case-control study was conducted of patients presenting with conjunctival masses at a tertiary eye hospital in Johannesburg, South Africa. Patients completed an interview and had three non-invasive diagnostic tests: optical coherence tomography, impression cytology and methylene blue stain. A biopsy with histology was performed as the gold standard to confirm the diagnosis.

RESULTS

One hundred and eighty-two conjunctival masses of 175 patients were evaluated. There were 135 lesions identified as OSSN on biopsy and 47 lesions were benign on histology. Optical coherence tomography had a sensitivity and specificity of 87.2% (95% CI: 80.0-92.5) and 75.6% (95% CI: 60.5-87.1), respectively, when an epithelial thickness cutoff of 140 um was used. Shadowing was found in 46% of cases due to leukoplakia or increased thickness of the mass. Cytology had a sensitivity of 72.4% (95% CI: 62.5-81.0) and a specificity of 74.3% (95% CI: 56.7-87.5). Twenty-seven per cent of cytology specimens were excluded from analysis due to inadequate cellularity. Methylene blue had a high sensitivity of 91.9% (95% CI: 85.9-95.9), but low specificity of 55.3% (95% CI: 40.1-69.8).

CONCLUSION

Optical coherence tomography had a high sensitivity and specificity as a non-invasive test and liquid-based cytology performed well but had a lower sensitivity and specificity than with optical coherence tomography. Methylene blue performed well as a screening test, with a high sensitivity but low specificity.

Comparison in conjunctival-Tenon's capsule thickness, anterior scleral thickness and ciliary muscle dimensions between Caucasians and Hispanic by optical coherence tomography

PURPOSE

To investigate the differences in the dimensions of the anterior ocular segment, and specifically in conjunctival-Tenon's capsule thickness (CTT), anterior scleral thickness (AST) and ciliary muscle thickness (CMT), between Caucasian and Hispanic subjects using swept-source optical coherence tomography (SS-OCT).

METHODS

Cross-sectional study including 53 Hispanic and 60 Caucasian healthy participants, matched by age, sex and refractive error, who underwent a complete ophthalmological examination. CTT, AST and CMT were manually measured in the temporal and nasal quadrants at 0, 1, 2 and 3 mm from the scleral spur using SS-OCT.

RESULTS

Mean age and refractive error were 38.7 ± 12.3 years and -1.05 ± 2.6 diopters, and 41.8 ± 11.7 years and -0.50 ± 2.6 diopters for the Hispanic and Caucasians, respectively (p = 0.165 and p = 0.244). The CTT was increased in the temporal quadrant in the Hispanic group in the three studied regions (CTT1, CTT2 and CTT3; being the means 223.0 ± 68.4, 215.3 ± 66.4 and 203.8 ± 67.1 µm versus 190.8 ± 51.0, 189.4 ± 53.2 and 187.4 ± 55.3 µm respectively; p < 0.001). Larger AST values were observed in the temporal quadrant in the Hispanic group (AST2: 559.8 ± 80.8 µm and AST3: 591.6 ± 83.0 µm) compared to the Caucasian group (520.7 ± 50.1 and 558.9 ± 54.7 respectively; p ≤ 0.022). No differences were observed in the nasal quadrant for CTT, AST1 and AST3 (p ≥ 0.076). No differences emerged in the CM dimensions (p ≥ 0.055).

CONCLUSION

CTT and AST measurements were thicker in the temporal quadrant of Hispanic patients compared to Caucasians. This could have implications for the pathogenesis of different ocular diseases.

The role of anterior segment optical coherence tomography in the evaluation of the pterygium

BACKGROUND

To evaluate the ability of anterior segment optical coherence tomography (AS-OCT) to visualize the anatomic features of the pterygium and its invasion of the corneal layers.

METHODS

Seventy-five eyes of 54 patients diagnosed with pterygium were included. All subjects underwent complete ophthalmologic examinations, including AS-OCT. The limbus-apex distance, vertical height at the limbus, invasion of the Bowman's and stromal layers, and other morphologic structures of the pterygium tissue were analyzed.

RESULTS

The mean age of the patients was 49.67 ± 16.49 (20-85) years. The mean apex-limbus distance was 2548.37 ± 1026.32 (933-4597) μm, and the mean vertical height at the limbus was 4843.89 ± 1374.10 (1740-7784) μm. A space was observed beneath the pterygium tissue in 44 (58.67%) eyes. The mean width and height of this space were 1756.33 ± 560.22 (1009-3095) μm and 231.70 ± 85.88 (109-465) μm, respectively. Invasion of the Bowman's layer was apparent in 74 (98.67%) eyes, and invasion of the stromal layer was detected in 33 (44%) eyes. A hyperreflective layer was observed beneath the epithelial layer at the edge of the pterygium apex in 31 (41.33%) eyes. In 24 (92.31%) of the 26 advanced pterygium cases and 20 (40.82%) of the 49 early pterygium cases, a subpterygium space was found beneath the lesion (p = 0.0001).

CONCLUSION

AS-OCT enables measurement of the actual size and thickness of pterygia, assessment of invasion of the Bowman's and stromal layers of the cornea, and evaluation of the pterygium structure. Over half of the eyes exhibited space beneath the pterygium.

Clinic-pathological agreement in the diagnosis of conjunctival tumours: Analysis of 195 cases

PURPOSE

The present study aims to assess the agreement between clinical and pathological diagnosis in conjunctival tumours in a specialist ocular oncology unit.

METHODS

retrospective study of consecutive patients with conjunctival tumours diagnosed at the Ocular Oncology Unit of the University Hospital of Valladolid was performed from 1992 to 2017. Tumours were classified according to their origin (epithelial, melanocytic, lymphoid and others) and degree of malignancy (benign, premalignant, malignant). A biopsy was performed in cases of symptomatic or growing lesions. Cohen´s kappa (κ) statistics was used as an indicator of agreement between clinical and pathological diagnosis.

RESULTS

Of 462 consecutive patients, a biopsy was required in 195 (42.2%). The agreement with the pathological diagnosis was successful in 154 (79.0%) cases. Analysis according to the grade of malignancy showed the lowest rate of agreement among benign (n = 83; 91.6%) and premalignant (n = 62; 90.3%) lesions, with a total agreement in malignant lesions (n = 50; 100%); the Cohen´s kappa coefficient (κ) was 0.90. The highest rates of concordance were found in epithelial, melanocytic and soft tissue lesions with κ values of 1, 0.8 and 1 respectively. The worst rate of concordance was found in lymphoid lesions with a κ value of 0.3.

CONCLUSION

Most of the conjunctival tumours were correctly identified clinically; benign and malignant lesions showed the highest rate of accuracy; however, premalignant tumours can hide micro-invasive diseases that can go unnoticed on clinical examination. The biopsy is essential for accurate diagnosis and treatment.

Corneal squamous neoplasia: masquerades and management outcomes at a rural eyecare centre

The authors describe two cases of corneal ocular surface squamous neoplasia (OSSN), presenting at our rural eyecare centre, which were initially misdiagnosed as viral epithelial keratitis and corneal pannus with focal limbal stem cell deficiency. Both the cases were refractory to initial treatment and corneal OSSN was suspected. Anterior segment-optical coherence tomography (AS-OCT) revealed a thickened, hyper-reflective epithelium with abrupt transition and an underlying cleavage plane, features typical of OSSN. Topical 1% 5-fluorouracil (5-FU) therapy was initiated and in two cycles (first case) to three cycles (second case), complete resolution was noted both clinically and on AS-OCT, with no significant side effects. Both patients are currently free of tumour at the 2-month follow-up period. The authors report the rare, atypical presentations of corneal OSSN, discuss the masquerades and highlight the role of primary topical 5-FU in managing corneal OSSN in limited resource settings.

Anterior segment optical coherence tomography in ocular surface tumours and simulating lesions

This study aims to systematically review the reported literature on the use of anterior segment optical coherence tomography (AS-OCT) in ocular surface tumours and simulating lesions. A systematic literature search was done using PubMed, Scopus, and Web of Science databases between January 2002 and December 2021. On AS-OCT, ocular surface squamous neoplasia typically demonstrate epithelial thickening, epithelial hyperreflectivity, and an abrupt transition between normal and abnormal epithelium. Conjunctival nevi usually show mildly hyperreflective epithelium of normal thickness, internal hyperreflectivity, and intralesional cysts which is the hallmark of this tumour. Primary acquired melanosis presents with normal thickness epithelium, basal epithelial hyperreflectivity, and absence of cysts. Conjunctival melanoma demonstrates hyperreflective normal/thickened epithelium, hyperreflective basal epithelium, internal hyperreflectivity, and absence of intralesional cysts. Conjunctival lymphoma shows homogenous, low-medium reflective subepithelial lesions with smooth borders, and dot-like infiltrates. Benign reactive lymphoid hyperplasia findings are similar to lymphoma but the infiltrates are more hyperreflective compared to lymphoma. Pterygium shows thickened conjunctival epithelium, epithelial hyperreflectivity, and subepithelial wedge-shaped hyperreflective tissue separated from the overlying epithelium by a cleavage plane. Pinguecula demonstrates mildly thickened epithelium and similar findings with pterygium but does not extend beyond the corneal limbus. This review shows that AS-OCT, as a noninvasive tool, has potential uses in the differential diagnosis of ocular surface tumours and simulating lesions. Major limitations of AS-OCT include limited visualization of the posterior border of thick, keratinized, and pigmented tumours and lack of assessment of large conjunctival tumours in a single cut.

Clinical and Optical Coherence Tomography Comparison Between Ocular Surface Squamous Neoplasia and Squamous Metaplasia

PURPOSE

The purpose of this study was to compare the clinical characteristics and high-resolution optical coherence tomography (HR-OCT) findings between corneal squamous metaplasia and ocular surface squamous neoplasia (OSSN).

METHODS

A retrospective case-control study of 8 patients, 4 with histologically confirmed squamous metaplasia and 4 with histologically confirmed OSSN, who presented to the Miami Veterans Administration Medical Center and Bascom Palmer Eye Institute between 2016 and 2020 was performed. Clinical characteristics, HR-OCT findings, and pathology were evaluated and compared.

RESULTS

Four patients with squamous metaplasia and 4 with OSSN were evaluated. In the metaplasia group, 75% were male, 2 were White, and 2 were Black. In the OSSN group, all 4 were White males. All lesions were opalescent and occurred at the limbus; however, the borders were more smooth and rounded in the metaplastic lesions compared with OSSN. HR-OCT findings were indistinguishable between the 2 groups.

CONCLUSIONS

There is overlap in clinical characteristics and HR-OCT findings between corneal squamous metaplasia and OSSN, highlighting one limitation of HR-OCT. As such, if a corneal opacity has some but not all HR-OCT findings of OSSN, squamous metaplasia should also be considered. A biopsy may be indicated to further evaluate and guide treatment.

Medical treatment for ocular surface squamous neoplasia

Ocular surface squamous neoplasia (OSSN) is the most common non-melanocytic tumour of the ocular surface. Surgical excision with wide margins using the "no-touch" method was originally the most popular treatment for OSSN. However, in the past two decades, the use of topical medications for OSSN treatment has gained a reputation amongst ophthalmologists for being an effective alternative to surgical excision. Furthermore, technological advancements, such as those seen in high-resolution optical coherence tomography (HR-OCT) for the anterior segment, have facilitated the diagnosis and monitoring of OSSN. When selecting a topical agent, interferon alpha-2b (IFNα-2b) and 5-fluorouracil (5-FU) are two of the gentlest medications used for OSSN and are often considered first line therapies due to their high-resolution rates and mild side effect profiles. Mitomycin C (MMC), on the other hand, has a highly toxic profile; therefore, while effective, in our hands it is considered as a second-line treatment for OSSN if the other modalities fail. In addition, newer and less studied agents, such as immune checkpoint inhibitors, retinoic acid, aloe vera, and anti-vascular endothelial growth factor have anti-neoplastic properties and have shown potential for the treatment of OSSN. We enclose an updated literature review of medical treatments for OSSN.

Anterior segment optical coherence tomography characteristics of conjunctival papilloma as compared to papilliform ocular surface squamous neoplasia

PURPOSE

To describe the anterior segment optical coherence tomography (AS-OCT) appearance of conjunctival papilloma and identify differentiating features from papilliform ocular surface squamous neoplasia (OSSN).

METHOD

A retrospective chart review of individuals clinically diagnosed with conjunctival papilloma (n = 10) or papilliform OSSN (n = 10) based on slit lamp features. Data on demographics, tumour characteristics, and primary treatment were collected. AS-OCT features were assessed including epithelial thickness and reflectivity, a corrugated epithelial surface, presence of an overhanging edge, presence of intrinsic spaces and posterior shadowing. Histopathology was available in 5 papilloma and 3 OSSN specimens.

RESULT

Overall, the majority of individuals in both groups were white males. OSSN lesions were more likely to involve the limbus (80% vs.10%, p = 0.005) and the bulbar conjunctiva (100% vs. 20%, p < 0.001) compared to papillomas. On AS-OCT, maximum epithelial thickness was thicker in papilloma compared to OSSN (936 ± 533 vs. 637 ± 207 µm, p = 0.009). The feature that best differentiated papilloma from OSSN was an overhanging edge (100% vs. 0%, p < 0.001), where the epithelial lesion was seen on top of underlying normal epithelium. Other features more common in papilloma compared to OSSN included a corrugated epithelial surface (70% vs.10%, p = 0.02), the presence of intrinsic spaces (100% vs. 50%, p = 0.03), and posterior shadowing (100% vs. 40%, p = 0.01).

CONCLUSION

AS-OCT shows differentiating features between papilloma and OSSN with an overhanging edge as a distinctive AS-OCT feature of papilloma.

How Can We Diagnose Ocular Surface Squamous Neoplasia With Optical Coherence Tomography?

AIM

We aimed to evaluate the effectiveness of optical coherence tomography (OCT) in the differential diagnosis of anterior segment diseases such as ocular surface squamous neoplasia (OSSN) and pterygium.

METHODS

Patients who were pre-diagnosed with either OSSN (21) or pterygium (19) between January 2020 and November 2022 were included in this retrospective study. Anterior segment photographs and anterior segment optical coherence tomography (AS-OCT) measurements were obtained from each patient. Excisional or incisional biopsy materials underwent pathological evaluation.

RESULTS

Preoperative AS-OCT images of the patients with OSSN showed similarities with histopathological specimens. Both ocular and pathological specimens appeared to have a thicker epithelial layer with a distinct change from healthy to neoplastic epithelium. Preoperative AS-OCT images of individuals with pterygium were also comparable with histopathological samples. Both pathological and AS-OCT images of the pterygium patients showed a normal thickness epithelium and a thickened subepithelial layer under the epithelium. The mean epithelial thickness measured with AS-OCT in OSSN patients was found to be 295.3 ± 111.3 µm, while it was 80.7 ± 43.4 µm in pterygium patients. The difference was statistically significant (P<0.001). The receiver operating characteristic (ROC) curve analysis revealed a cut-off value of 97 µm for the differential diagnosis of OSSN from pterygium, with a sensitivity of 100% and specificity of 94.7%.

CONCLUSIONS

AS-OCT can be used as a noninvasive diagnostic tool for the evaluation of ocular surface lesions. Its ability to distinguish between OSSN and pterygium is demonstrated by the statistically significant difference in epithelial thickness and the significant morphological association with histopathological findings.

The Management of Ocular Surface Squamous Neoplasia (OSSN)

The rise of primary topical monotherapy with chemotherapeutic drugs and immunomodulatory agents represents an increasing recognition of the medical management of ocular surface squamous neoplasia (OSSN), which may replace surgery as the standard of care in the future. Currently, there is no consensus regarding the best way to manage OSSN with no existing guidelines to date. This paper seeks to evaluate evidence surrounding available treatment modalities and proposes an approach to management. The approach will guide ophthalmologists in selecting the most appropriate treatment regime based on patient and disease factors to minimize treatment related morbidity and improve OSSN control. Further work can be done to validate this algorithm and to develop formal guidelines to direct the management of OSSN.

Evaluation of the Effects of Pterygium and Aging on Limbal Structure Using Optical Coherence Tomography

Previous studies suggest that regions of corneal limbus may possess structural differences. We aimed to investigate the limbal changes associated with pterygium and aging via optical coherence tomography (OCT). Palisades of Vogt epithelial thickness (POV-ET) and Bowman’s membrane epithelial thickness (BM-ET) were measured at the nasal, temporal, superior, and inferior quadrants of patients with pterygium and healthy subjects of different ages. Values were expressed as a ratio that functioned as an index used to evaluate the change of limbus. Ratio values determined for quadrants of the corneal limbus were correlated highly in young healthy subjects. Further, parameter values were significantly greater than those of elder healthy subjects. In young subjects, the temporal and superior quadrants of patients with pterygium were significantly lower than those of healthy subjects. Temporal and superior quadrants of elder pterygium patients affected by both pterygium and age were significantly lower than those of healthy subjects; however, the inferior quadrant of elderly pterygium patients was significantly higher than that of age-matched healthy subjects. Our findings revealed that the thickness of limbal epithelium was negatively correlated with age, while pterygium led to the thinning of the temporal and superior limbal epithelium and inferior limbal epithelial thickening.

Ocular Surface Squamous Neoplasia Masquerading as Recalcitrant Epithelial Keratitis

PURPOSE

The purpose of this study was to report a unique case of ocular surface squamous neoplasia that masqueraded as a nonresolving toxic epithelial keratitis.

METHODS

This was a case report and review of the literature.

RESULTS

A 79-year-old man presented with decreased vision, redness, and a foreign body sensation in his right eye that was refractory to treatment with lubrication and topical nonsteroidal antiinflammatory drops. Before presentation, the referring provider believed that he had medicamentosa-related keratitis and placed him on oral methazolamide. Slitlamp biomicroscopy of the right eye revealed diffuse epitheliopathy with punctate fluorescein staining and subtle underlying corneal epithelial opalescence. A mildly thickened and inflamed pinguecula was noted from 2 to 5 o'clock at the limbus of the right eye. An anterior segment high-resolution optical coherence tomography revealed thickened, hyperreflective epithelium with an abrupt transition. An incisional biopsy confirmed conjunctival and corneal intraepithelial neoplasia. The patient improved after 4 cycles of topical chemotherapy with 1% 5-fluorouracil eye drops with complete resolution of the corneal and conjunctival pathology.

CONCLUSIONS

Ocular surface squamous neoplasia can rarely masquerade as a recalcitrant medicamentosa and epithelial keratitis. In subtle cases or in cases with combined ocular surface morbidities, anterior segment high-resolution optical coherence tomography can be helpful to diagnose and direct therapy.

Topical pharmacotherapy for ocular surface squamous neoplasia: systematic review and meta-analysis

Ocular surface squamous neoplasia (OSSN) has different treatment modalities. Although surgical excision has been the gold standard therapeutic option, topical pharmacotherapy agents such as 5-fluorouracil (5-FU), interferon alfa-2b (IFN) and mitomycin-C (MMC) are also commonly used. The protocol was registered (CRD42021224961). Comprehensive literature research was carried out to compare topical pharmacotherapy (5-FU or IFN or MMC) to surgical excision regarding clinical success (tumor resolution), recurrence and complications in patients undergoing treatment for OSSN. From 7859 records, 7 articles were included in the qualitative and 4 in the quantitative synthesis. The outcomes of surgical excision and topical pharmacotherapy were comparable in the included articles. There were no significant differences between surgical excision and topical pharmacotherapy regarding the clinical success [odds ratio (OR): 0.785; confidence interval (CI): 0.130-4.736, P = 0.792)] and tumor recurrence (OR: 0.746; CI: 0.213-2.609; P = 0.646). The most common side effect of the different therapeutic options was dry eye. The highest rate of dry eye symptoms was reported after surgical excision (in 59%). Topical pharmacotherapy with all the 3 agents is as effective and well-tolerable as surgical excision in terms of tumor resolution, recurrence rate and side effects in all OSSN patients suggesting similar long-term clinical benefits.

Ocular Surface Squamous Neoplasia: A 12-Month Prospective Evaluation of Incidence in Waikato, New Zealand

Ocular surface squamous neoplasia (OSSN) has a high incidence in the southern hemisphere. This prospective study evaluated the incidence of OSSN in the Waikato region of New Zealand. All patients presenting with pterygium or conjunctival lesions in the Waikato region in 2020 were included. All surgeons in the region were asked to send all conjunctival and corneal specimens excised for histopathologic examination. The primary outcome measure was the incidence of OSSN. Eighty-eight percent of all excised specimens were sent for histopathologic examination. Of the 185 excised lesions sent for histopathological assessment, 18 (10%) were reported as OSSN. Patients were on average 69.4 years of age (standard deviation, SD = 6.9), predominantly male (78%), and of New Zealand-European ethnicity (89%). The OSSN annual incidence was 3.67/100,000/year. Histology grades included conjunctival intraepithelial neoplasia (CIN)-I (25%), CIN-II (25%), CIN-III (12.5%), carcinoma in situ (25%), and invasive squamous cell carcinoma (SCC) (12.5%). One patient with invasive SCC required exenteration. This study identified a high incidence rate of OSSN and is the first prospective study to analyze OSSN epidemiology in New Zealand.

Topical Chemotherapy for Treating Ocular Surface Squamous Neoplasia with a Combination of Interferon α-2b and 5-Fluorouracil

Introduction

This study evaluated the efficacy of combined interferon α-2b (IFNα2b) and 5-fluorouracil (5-FU) as primary treatment for ocular surface squamous neoplasia (OSSN).

Methods

In this retrospective study, 27 eyes with OSSN followed by topical application of combined IFNα2b and 5-FU were examined. Reported outcome measures were tumor response, visual acuity, time to complete resolution, recurrence and treatment complications.

Results

Twenty-six patients (17 male, 9 female) had a mean age of 63.9 (median, 67; range 22–83) years. Complete tumor response was observed in 24 eyes (88.9%). Three eyes (11.1%) showed partial response to the chemotherapy agents and later underwent surgical tumor removal. The median time to complete resolution was 6 (mean, 6.1; range, 3–11) weeks. Of these, the patients received between one to three cycles of 5-FU therapy (median, 2; mean, 1.8). Complications noted were transient irritation at 5-FU cycle (11 eyes, 40.7%). There was no tumor recurrence at mean follow-up of 16.1 (median, 12; range 6–38) months.

Conclusions

Combination therapy of IFNα2b and 5-FU was a safe and effective treatment, inducing a short duration of administration and low recurrence rate for OSSN.

Trial Registration

Retrospectively registered, UHCT22048.

Role of AS-OCT in Managing Corneal Disorders

Optical coherence tomography (OCT) is analogous to ultrasound biometry in the cross sectional imaging of ocular tissues. Development of current devices with deeper penetration and higher resolution has made it popular tool in clinics for visualization of anterior segment structures. In this review, the authors discussed the application of AS-OCT for diagnosis and management of various corneal and ocular surface disorders. Further, recent developments in the application of the device for pediatric corneal disorders and extending the application of OCT angiography for anterior segment are introduced.

The use of high resolution optical coherence tomography (HR-OCT) in the diagnosis of ocular surface masqueraders

INTRODUCTION

Ocular surface masqueraders encompass any ocular surface lesion masquerading as another ocular surface lesion. High resolution optical coherence tomography (HR-OCT) has emerged as an adjunctive tool to clinical acumen. This study's purpose is to evaluate the utility of HR-OCT images in guiding the diagnosis and management of those lesions.

MATERIAL AND METHODS

22 individuals with a clinically ambiguous ocular surface lesion with slit lamp photographs (SLP), HR-OCT images, and histopathological examination were included in the study. The presumptive clinical diagnosis based on SLP was compared to the diagnosis suggested by HR-OCT findings and to definitive diagnosis by histopathology. The main outcome of this study was the frequency in which HR-OCT findings guided the clinician to the correct diagnosis.

RESULTS

7 lesions were epithelial, 3 had an epithelial and a subepithelial component, and 12 were subepithelial. HR-OCT was most effective in discerning lesion location, successfully identifying the location in 100% of cases. Classic HR-OCT findings were detected in 68.2% of cases while suggestive features were detected in 31.8% of cases. The epithelial lesions' mean epithelial thickness was 265.4 ± 140.6 μm, the subepithelial lesions' mean was 58.0 ± 25.0 μm, and the combined lesions' mean was 140.0 ± 70.0 μm. The epithelium was significantly thicker in epithelial lesions compared to subepithelial and combined lesions. By ROC analysis we identified that using a cut off of 156 μm, the sensitivity was 86% and the specificity was 93%.

DISCUSSION

HR-OCT can be a valuable diagnostic tool, assisting in the differentiation of ambiguous ocular surface pathologies by providing a cross-sectional, morphological image of the lesion.

Ocular surface squamous neoplasia in Northern Thailand: a 16-year review

Purpose

To evaluate clinical characteristics, treatments, and outcomes in patients with ocular surface squamous neoplasia (OSSN) at a tertiary center in Northern Thailand.

Methods

Patients diagnosed with either corneal-conjunctival intraepithelial neoplasia (CIN) or squamous cell carcinoma (SCC) from May 2000 to December 2015, were recruited. The patients’ demographics, symptoms, clinical characteristics, cytopathology, treatments, and outcomes were reviewed.

Results

Overall 171 eyes from 168 patients, 92 eyes were CIN and 79 eyes were SCC. Males were affected in 65.5%. The mean age was 58.8 ± 16.8 (29–99) years. In most cases (60.3%), the tumors were located at the limbus. The most common clinical characteristic was papilliform appearance (46.2%). Human immunodeficiency virus (HIV) infection was found in 37 (22.0%) patients with a mean age of 40.5 ± 7.7 years. The treatments and outcomes were evaluated in 136 eyes whose main initial treatment was wide excision with adjunctive cryotherapy (47.8%), followed by topical mitomycin C (30.9%). The mean follow-up time after treatment was 20.8 ± 2.2 (3–110) months and the recurrence occurred in 18 eyes (13.2%) during the follow-up period. The mean recurrence-free time (months) for CIN was significantly longer than that of SCC (81.3 ± 10.0 [95%CI 61.5 – 101.1] vs 33.2 ± 4.6 [95%CI 24.0 – 42.3], p = 0.030). SCC was the only significant risk factor that influences the recurrence of the tumors with the adjusted hazard ratio of 5.69 (p = 0.005).

Conclusion

OSSN in Northern Thailand usually involved a limbal area and presented as a papilliform mass. HIV infection should be suspected in young patients. CIN had better outcomes after treatments than invasive SCC.

Functional impact of titin (TTN) mutations in ocular surface squamous neoplasia

Mutations in the titin (TTN) gene are among the most common genomic aberrations in ocular surface squamous neoplasia (OSSN), the most common cancer of the external eye. Further, TTN mutations are associated with resistance to standard therapy with topical interferon alpha-2b (IFN-α2b). However, it remains unclear how TTN mutations drive OSSN pathogenesis and treatment resistance. TTN encodes the largest protein in the human body and its best understood function is as a myofibril scaffold in striated muscle. However, recent evidence indicates that TTN has additional functions in non-muscle cells and in cancer. Here, we performed a disorder-based bioinformatics analysis which revealed that intrinsically disordered protein regions are abundant in TTN and provide mechanistic insights into its function as a nuclear protein in epithelial cells. Specific mutations found in OSSN are predicted to affect its intrinsically disordered protein regions (IDPRs), promoting chromosomal instability, oncogenesis, and altered response to IFN-α2b treatment.

Update on the Management of Ocular Surface Squamous Neoplasia

Purpose of review

To review and update the latest findings in diagnosis and management of ocular surface squamous neoplasia (OSSN).

Recent findings

OSSN is the most common anterior segment neoplastic disease process. Several ocular surface imaging techniques have been developed for the early diagnosis and management of clinical and subclinical ocular surface squamous neoplasia, including high-resolution optical coherence tomography (HR-OCT), in vivo confocal microscopy, and ultrasound biomicroscopy. Treatment modalities include both surgical and medical management, with a recent trend towards primary and adjunctive pharmacotherapy.

Summary

There is increasing use of HR-OCT for the diagnosis and monitoring of clinical and subclinical OSSN lesions. Topical pharmacotherapy agents, including interferon α-2b, 5-fluorouracil, and mitomycin C, have demonstrable efficacy in the treatment of OSSN and their use may be dictated based upon tumor factors, patient factors, cost, and side effect profile. Both surgical excision and adjunctive topical medications have excellent success, with the favored treatment method trending towards topical pharmacotherapy as primary therapy.

Evaluation of pterygium severity with en face anterior segment optical coherence tomography and correlations with in vivo confocal microscopy

PURPOSE

To describe en face anterior segment optical coherence tomography (EF-OCT) characteristics of pterygia and their correlation with in vivo confocal microscopy (IVCM).

PATIENTS AND METHODS

In this observational case series, we prospectively included 21 eyes of 17 subjects with pterygium. All subjects underwent detailed ophthalmic examination, anterior segment photography, an ocular surface disease index (OSDI) questionnaire, IVCM, and EF-OCT. Eyes were divided into two groups according to pterygium severity (Modified Pterygium Classification System) and OSDI score. EF-OCT images for both groups were analyzed for surface area of Fuchs Patches (FP). The IVCM activity score was based on the number of inflammatory cells, blood vessels, activated keratocytes and the appearance of the cornea/pterygium at the head of the pterygium. The correlations between EF-OCT and IVCM images were then analyzed and compared in both groups.

RESULTS

EF-OCT permits clear visualization and evaluation of FPs and the border between the pterygium and the adjacent cornea. The severe pterygium group was characterized by irregular borders and larger FPs (0.13±0.06 mm² versus 0.06±0.02 mm² respectively) (P=0.003). The mean IVCM activity score was 2.36±0.81 in the severe pterygium group and 1.2±0.42 in the mild pterygium group (P=0.0013). There was a positive correlation between FP surface area and IVCM activity score. A larger FP surface area was associated with a higher activity score on IVCM.

CONCLUSION

EF-OCT allows good evaluation of pterygium extension, borders and FP surface area. EF-OCT analysis of pterygium could represent a simple, non-invasive and reproducible method to evaluate pterygium severity and activity.

Case Series: High-resolution Optical Coherence Tomography as an Optical Biopsy in Ocular Surface Squamous Neoplasia

SIGNIFICANCE

Ocular surface squamous neoplasias are superficial tumors of the cornea and conjunctiva that can be sight threatening if neglected. Therefore, accurate noninvasive diagnostic modalities are needed.

PURPOSE

The purpose of this case series was to describe the hallmark features of ocular surface squamous neoplasia on high-resolution optical coherence tomography (HR-OCT) imaging and its use in the evaluation and management of superficial ocular tumors.

CASE SERIES

Five eyes of four patients with ocular surface squamous neoplasia are described. Whereas two eyes displayed the classic clinical features of ocular surface squamous neoplasia, three of the five eyes had more subtle atypical features. However, all shared features on HR-OCT of epithelial thickening and hyperreflectivity with abrupt transitions between normal and abnormal tissue, classic features of ocular surface squamous neoplasia. All lesions ultimately underwent incisional or excisional biopsy and were confirmed to be ocular surface squamous neoplasia on histopathology.

CONCLUSIONS

Ocular surface squamous neoplasia may present as a classic tumor but can also have subtle features or masquerade. Accurate methods to diagnose and manage patients with ocular surface squamous neoplasia are necessary. With recent advancements in technology, HR-OCT has been demonstrated to accurately identify ocular surface squamous neoplasia with the repeatable optical findings of (1) epithelial thickening, (2) epithelial hyperreflectivity, and (3) abrupt transition zone between normal and abnormal tissue. This case series demonstrates how HR-OCT can help provide an optical biopsy to guide appropriate diagnosis and management of this neoplastic lesion.

The role of imaging technologies for ocular surface tumors

PURPOSE OF REVIEW

This review will discuss the utility of high-resolution anterior segment optical coherence tomography (HR-OCT), in-vivo confocal microscopy (IVCM) and ultrasound biomicroscopy (UBM) in characterizing and diagnosing various ocular surface tumors, namely ocular surface squamous neoplasia (OSSN), conjunctival lymphoma and conjunctival melanoma. The strengths and limitations of each imaging modality will be discussed along with the characteristics findings of each lesion on each imaging platform.

RECENT FINDINGS

HR-OCT can consistently be utilized in the clinic setting to distinguish between epithelial ocular surface tumors such as OSSN as compared with subepithelial tumors such as conjunctival lymphoma and conjunctival melanoma given their distinctive findings. IVCM can be used as an adjunct to HR-OCT to obtain cellular and surface characteristics, whereas UBM can be used to assess tumor depth and thickness for larger and highly pigmented lesions as well as to detect intraocular invasion.

SUMMARY

HR-OCT, IVCM and UBM are all helpful imaging modalities to diagnose and characterize various ocular surface tumors and can serve as valuable adjuncts to monitor treatment response and assess for recurrence ocular surface tumors.

Impact of age, sex and refractive error on conjunctival and Tenon's capsule thickness dimensions by swept-source optical coherence tomography in a large population

PURPOSE

To evaluate conjunctival and Tenon's capsule thickness (CTT) in a large healthy population using swept-source optical coherence tomography (SS-OCT), investigating the impact of age, sex and refractive error.

METHODS

630 healthy participants underwent a complete ophthalmological examination. CTT was manually measured in the temporal and nasal quadrants at 0, 1, 2 and 3 mm from the scleral spur using SS-OCT (CTT0, CTT1, CTT2 and CTT3, respectively). These dimensions were then assessed for associations in a multivariate regression model with age, sex, refractive error and anterior scleral thickness (AST). The reproducibility of the CTT measurements was determined in 30 individuals.

RESULTS

CTT dimensions could be measured in 596 cases (94.6%); mean age was 42.6 ± 17.2 years (range 5-86). Mean CTT0 was 199.2 ± 33.8 and 192.9 ± 33.9 µm, mean CTT1 195.4 ± 38.0 µm and 199.9 ± 50.9 µm, mean CTT2 187.0 ± 38.4 and 194.8 ± 48.9 µm, and CTT3 180.5 ± 35.6 µm and 191.8 ± 43.7 µm, for the temporal and nasal quadrants, respectively. No difference in CTT was observed in the nasal versus temporal quadrant (p ≥ 0.106) except for the CTT0 and CTT3 (p = 0.001). Moderate correlation was observed between nasal and temporal CTT (R = 0.472, p < 0.001). In the multivariate model, no influence was observed by sex, refractive error and AST on CTT measurements (p ≥ 0.065). Negative association was observed between age and CTT (p < 0.005). The reproducibility was excellent (intraclass correlation coefficient ≥ 0.908).

CONCLUSIONS

SS-OCT allows for in vivo CTT evaluation. Our data document a wide range of measurements, showing negative association between CTT and age.

Morphometric evaluation and measurements of primary pterygium by anterior segment optical coherence tomography and its relation with astigmatism

Purpose:

To evaluate the relationship between measurements and various morphometric parameters of primary pterygium on anterior segment optical coherence tomography(AS-OCT) and refractive and keratometric astigmatism.

Methods:

In this cross-sectional study, patients with primary pterygium were included. The AS-OCT parameters of pterygium consisting of epithelial thickness near apex(µm), apical or head thickness(µm), its thickness at limbus(µm), horizontal length of pterygium(mm), central corneal thickness (µm) and maximum pterygium thickness(mm) were evaluated.

Results:

Sixty three patients comprising of 63 eyes with a primary pterygium were studied. The mean keratometric and refractive astigmatism were 1.69 ± 3.15 Diopter(D) and0.5 ± 1.4D, respectively. There was a significant association between pterygium grade and stocker’s line with keratometric astigmatism (p = 0.02, 0.00) respectively. Vertical and horizontal length on slit lamp and horizontal length on AS-OCT showed significant association with keratometric astigmatism (p = 0.05, 0.00,0.00), respectively. Limbal thickness on AS-OCT showed significant positive correlation with refractive astigmatism (r = 0.29, p = 0.02).

Conclusion:

The pterygium grade influences the keratometric astigmatism. Increased limbal thickness of pterygium on AS-OCT leads to more refractive astigmatism.

Pterygium: an update on pathophysiology, clinical features, and management

Pterygium is a relatively common ocular surface disease. The clinical aspects and the treatment options have been studied since many years ago, but many uncertainties still exist. The core pathologic pathway and the role of heredity in the development of pterygium are still attractive fields for the researchers. The role of pterygium in corneal irregularities, in addition to the refractive properties of pterygium removal, has been increasingly recognized through numerous studies. The association between pterygium and ocular surface neoplasia is challenging the traditional beliefs regarding the safe profile of the disease. The need for a comprehensive clinical classification system has encouraged homogenization of trials and prediction of the recurrence rate of the pterygium following surgical removal. Evolving surgical methods have been associated with some complications, whose diagnosis and management are necessary for ophthalmic surgeons. According to the review, the main risk factor of pterygium progression remains to be the ultraviolet exposure. A major part of the clinical evaluation should consist of differentiating between typical and atypical pterygia, where the latter may be associated with the risk of ocular surface neoplasia. The effect of pterygium on astigmatism and the aberrations of the cornea may evoke the need for an early removal with a purpose of reducing secondary refractive error. Among the surgical methods, conjunctival or conjunctival-limbal autografting seems to be the first choice for ophthalmic surgeons because the recurrence rate following the procedure has been reported to be lower, compared with other procedures. The use of adjuvant options is supported in the literature, where intraoperative and postoperative mitomycin C has been the adjuvant treatment of choice. The efficacy and safety of anti–vascular endothelial growth factor agents and cyclosporine have been postulated; however, their exact role in the treatment of the pterygium requires further studies.

Limbal stem cell diseases

The function of limbal stem/progenitor cells (LSCs) is critical to maintain corneal epithelial homeostasis. Many external insults and intrinsic defects can be deleterious to LSCs and their niche microenvironment, resulting in limbal stem cell dysfunction or deficiency (LSCD). Ocular comorbidities, frequent in eyes with LSCD, can exacerbate the dysfunction of residual LSCs, and limit the survival of transplanted LSCs. Clinical presentation and disease evolution vary among different etiologies of LSCD. New ocular imaging modalities and molecular markers are now available to standardize the diagnosis criteria and stage the severity of the disease. Medical therapies may be sufficient to reverse the disease if residual LSCs are present. A stepwise approach should be followed to optimize the ocular surface, eliminate the causative factors and treat comorbid conditions, before considering surgical interventions. Furthermore, surgical options are selected depending on the severity and laterality of the disease. The standardized diagnostic criteria to stage the disease is necessary to objectively evaluate and compare the efficacy of the emerging customized therapies.

Non-malignant conjunctival epithelial masses with ocular surface squamous neoplasia-like optical coherence tomography features

PURPOSE

To observe and describe the anterior segment optical coherence tomography features of limbally localised non-malignant epithelial mass lesions METHODS: Thirteen patients (age: 66.9 ± 16.3 years) with conjunctival mass suggesting ocular surface squamous neoplasia with biomicroscopic examination were imaged using anterior segment ocular coherence tomography (anterior segment optical coherence tomography)/Cirrus HD-OCT, Model 4000, Carl Zeiss Meditec, Inc., Dublin, CA, and Spectralis HRA + OCT system, Heidelberg Engineering, Vista, CA/. Cases with ocular surface squamous neoplasia-like anterior segment optical coherence tomography (hyperreflective, thickened epithelium and an abrupt transition from normal to abnormal) were included in the study. Maximal thickness of the epithelium was measured. Histological diagnosis was gained from an excisional or incisional biopsy or impression cytology specimens.

RESULTS

In six patients (age: 68.5 ± 15.4 years) with ocular surface squamous neoplasia-like anterior segment optical coherence tomography features, the histological diagnosis was other than ocular surface squamous neoplasia (papilloma, parakeratosis and a keratotic plaque with mild dysplasia), and ocular surface squamous neoplasia in seven cases (age: 65.6 ± 18.0 years). The maximal epithelial thickness was between 250 and 859 µm in non-ocular surface squamous neoplasia cases and between 252 and 596 µm in ocular surface squamous neoplasia cases.

CONCLUSION

Non-malignant epithelial lesions can mimic ocular surface squamous neoplasia on anterior segment optical coherence tomography.

Anterior segment optical coherence tomography and ultrasound biomicroscopy for measuring thickness of corneal and bulbar conjunctival tumours

BACKGROUND/OBJECTIVE

Anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM) are two non-invasive imaging techniques used for the measurement of tumour thickness in corneal and bulbar conjunctival tumours. Histopathology (HP), however, remains the gold standard for the measurement of tumour thickness. The aim of this study was to determine whether AS-OCT and UBM are as accurate as HP for measuring tumour thickness.

METHODS

Forty-two corneal and bulbar conjunctival tumours were imaged using AS-OCT and UBM. Images were assessed and tumour thickness was measured. Eleven patients subsequently underwent surgical excision. All specimens were measured during histopathological analysis. The correlation of the thickness measurement on HP to AS-OCT and UBM was then statistically analysed. In cases where the tumour was not excised, thickness measurement comparisons between AS-OCT and UBM were analysed.

RESULTS

AS-OCT and UBM measurements of tumour thickness were found to be significantly positively correlated (p=<0.001), as were UBM and HP thickness measurements (p=0.031). HP and AS-OCT measurements, however, only showed a mild but non-significant positive correlation.

CONCLUSION

Both AS-OCT and UBM are useful techniques to image and measure the thickness of corneal and conjunctival bulbar tumours. While AS-OCT provides better details than UBM, it was more limited in visualising the posterior boundary of the tumour, particularly in malignant tumours. While thickness measurements of both methodologies were correlated, neither should yet be considered as replacements to the gold standard of HP.

Comparative evaluation of clinical characteristics of biopsy-proven conjunctival intraepithelial neoplasia and invasive squamous cell carcinoma using image processing software programs

PURPOSE

To identify morphological parameters aiding clinical differentiation of conjunctival intraepithelial neoplasia (CIN) and invasive squamous cell carcinoma (iSCC) and to demonstrate the utility of image processing software to objectively assess ocular surface squamous neoplasia (OSSN).

METHODS

This retrospective case series included all biopsy-proven cases of OSSN presenting as an ocular surface nodule. Based on histopathology, lesions were classified as CIN and iSCC. Clinical image analysis utilized 'Contour' and 'ImageJ' software. The effect of predictors demography, seropositivity, lesion dimensions, keratin, pigmentation, corneal involvement, vascularity and feeder vessels on the final histopathologic grade were assessed.

RESULTS

A total of 108 OSSN lesions (74 CIN and 33 iSCC) were included. Mean age was 46.1 ± 17.2 years in CIN and 47.2 ± 13.9 years in iSCC. By univariate logistic regression analysis, significant predictors of iSCC were HIV seropositivity (p < 0.0001), maximum diameter (p = 0.003), perpendicular to maximum diameter (p = 0.003), height (p = 0.003), nodular morphology (p = 0.006) and feeder vessels (p = 0.03), whereas gelatinous morphology (p = 0.02) was predictor of CIN. By multiple logistic regression, seropositivity was the predictor of iSCC (p < 0.0001, OR 13.33 ± 8.35, 95% CI 3.90-45.53).

CONCLUSION

HIV seropositivity is an important predictor of iSCC. Large, thick, nodular lesions with feeder vessels may favor the diagnosis of iSCC, whereas gelatinous, small, flatter lesions without feeder vessels may favor CIN. In a first of its kind study, simple and objective analysis of OSSN with image processing software was demonstrated.

Diagnosis and staging of ocular surface squamous neoplasia

Background: Ocular surface squamous neoplasia (OSSN) is the most common ocular tumour. The diagnosis of OSSN is based on clinical suspicion and confirmed by various diagnostic modalities, of which histology is the gold standard. With the move to less invasive management options such as topical chemo- or immunotherapy, less invasive diagnostic options have come to the fore.Aim: The purpose of this article was to review the current staging and diagnostic modalities for OSSN with a focus on less invasive modalities.Method: A literature review was performed for publications on ocular surface neoplasia and diagnostic modalities.Results: Histology is the gold standard for diagnosing OSSN. Cytology has been shown to be a simple, repeatable and minimally invasive diagnostic modality, which also allows for additional testing such as polymerase chain reaction. Anterior segment optical coherence tomography provides a non-contact method of evaluating the ocular surface, with OSSN showing a thickened hyper-reflective epithelium, abrupt transition zone and demarcation line. Vital dyes are used less commonly with high sensitivity, but lower specificity for OSSN. Finally, confocal microscopy provides en-face images of the ocular surface, with OSSN showing a classic ‘starry night’ appearance.Conclusion: Histology remains the gold standard for diagnosis; however, with the increasing use of topical therapy for OSSN, there has been an increase in the uptake of less invasive diagnostic modalities.

Role of Conjunctival Ultraviolet Autofluorescence in Ocular Surface Squamous Neoplasia

Objective

To evaluate the adjunctive role of conjunctival autofluorescence in the management of ocular surface squamous neoplasia (OSSN).

Materials and Methods

Seventeen patients with clinically diagnosed OSSN were included. Morphological characteristics, type of OSSN, and autofluorescence photographs of the lesion were captured. Presence and area of conjunctival ultraviolet autofluorescence (CUVAF) were the main outcome measures.

Results

Overall, 17 patients with 15 (88%) primary and 2 (12%) recurrent OSSN were included. Common locations were temporal (n = 10), nasal (n = 5), and diffuse variety (n = 2). Morphologically, there were 4 (22.2%) nodular, 4 (22.2%) leucoplakic, 3 (16.7%) gelatinous, and 1 (5.5%) each of papillary, nodulo-ulcerative, and diffuse variety. Mixed morphology was present in 4 eyes (22.2%). Sixteen of 18 eyes (88.9%) with OSSN displayed autofluorescence on CUVAF images. The mean area of CUVAF was 15.82 mm² (10.77-19.59 mm²). Autofluorescence was reported in 8 eyes (44.4%) which had negative reports on impression cytology.

Conclusions

Conjunctival autofluorescence was seen in the majority of cases with OSSN, in spite of negative cytology reports. Our study demonstrates that CUVAF may serve as an effective ancillary, non-invasive, and resource-friendly tool for supplementing the clinical diagnosis of OSSN, especially in diffuse and recurrent lesions that are not amenable to surgical intervention.

Spectroscopic Optical Coherence Tomography for Thin Layer and Foil Measurements

The main goal of this research was to assess if it is possible to evaluate the thickness of thin layers (both thin films on the surface and thin layers below the surface of the tested object) and foils using optical coherence tomography (OCT) for thickness assessment under the resolution of the standard commercially available OCT measurement system. In the proposed solution, light backscattered from the evaluated thin layer has been expressed as a multiple beam interference. Therefore, the OCT system was modeled as a two-beam interferometer (e.g., Michelson), in which one beam propagates from the reference arm and the other comes from a Fabry-Pérot interferometer. As a consequence, the mathematical model consists of the main Michelson interferometer, in which the measuring arm represents the Fabry-Pérot interferometer. The parameters of the layer (or foil) are evaluated by analyzing the minimum value of the interference contrast. The model developed predicts the behavior of the thin layers made from different materials (with different refractive indexes) with different thickness and located at different depths. To verify the correctness of the proposed model, an experiment with a wedge cell has been carried out. The wedge cell was shifted across the scanning beam using a linear translation stage with a micrometer screw under the scanning head. The relationship between the thickness of the gap of the wedge cell and the OCT output signal is presented. For the additional verification of the proposed model, the results of the measurements of the thickness of the thin foil were compared with the theoretical results of the simulations. The film thickness was evaluated based on the calculated positions of the minimum value of interference contrast. A combination of the standard potentialities of OCT with the proposed approach to analyzing the signal produces new metrological possibilities. The method developed allows us to evaluate thickness under the resolution of the system and the location of the layer as well. This produces the possibility of measuring a layer which is covered by another layer. Moreover, it is possible to create a thickness map with high sensitivity to thickness changes. These experiments and simulations are the culmination of preliminary research for evaluating the potential of the proposed measurement method.

Intraoperative optical coherence tomography in anterior segment surgery

Intraoperative optical coherence tomography (iOCT) enables real-time visualization of ocular structures during surgery and enhances our understanding of intraoperative dynamics. iOCT aids in decision-making during various anterior segment surgeries, and its efficacy and feasibility in anterior lamellar keratoplasty and endothelial keratoplasty is well established. The landmark DISCOVER study observed that iOCT altered the surgeon decision in 38% of cases undergoing lamellar keratoplasty and provided guidance regarding the need for secondary surgical intervention. iOCT also finds an application in phacoemulsification wherein it helps to assess corneal incisions, intralenticular pressure, and posterior capsule integrity during nuclear emulsification. iOCT aids in the visualization of angle structures during placement of tubes and shunts in glaucoma surgeries and allows precise creation of partial thickness scleral flaps. In addition, iOCT helps in establishing a diagnosis, as well as provide intraoperative guidance, in pediatric patients who are not cooperative for examination. The role of iOCT in refractive surgeries and ocular surface disorders is increasingly being evaluated. The limitations of present-day iOCT systems are related to instrument compatibility, automated tracking of the surgical field, and on-table volumetric analysis of the real-time images. Technological advances may facilitate complete integration of OCT in the surgical microscopes for all surgical procedures.

Fourier-Domain OCT Imaging of the Ocular Surface and Tear Film Dynamics: A Review of the State of the Art and an Integrative Model of the Tear Behavior During the Inter-Blink Period and Visual Fixation

In the last few decades, the ocular surface and the tear film have been noninvasively investigated in vivo, in a three-dimensional, high resolution, and real-time mode, by optical coherence tomography (OCT). Recently, OCT technology has made great strides in improving the acquisition speed and image resolution, thus increasing its impact in daily clinical practice and in the research setting. All these results have been achieved because of a transition from traditional time-domain (TD) to Fourier-domain (FD) technology. FD-OCT devices include a spectrometer in the receiver that analyzes the spectrum of reflected light on the retina or ocular surface and transforms it into information about the depth of the structures according to the Fourier principle. In this review, we summarize and provide the state-of-the-art in FD-OCT imaging of the ocular surface system, addressing specific aspects such as tear film dynamics and epithelial changes under physiologic and pathologic conditions. A theory on the dynamic nature of the tear film has been developed to explain the variations within the individual compartments. Moreover, an integrative model of tear film behavior during the inter-blink period and visual fixation is proposed.

High resolution anterior segment optical coherence tomography for differential diagnosis between corneo-conjunctival intraepithelial neoplasia and pterygium

OBJECTIVE

To assess if anterior segment optical coherence tomography (AS-OCT) is a noninvasive diagnostic method suitable to differentiate benign corneo-conjunctival lesions (pterygium) from premalignant lesions (corneo-conjunctival intraepithelial neoplasia, CIN).

MATERIAL AND METHODS

An observational, analytical and cross-sectional study was conducted in 22 eyes with conjunctival lesions clinically suspicious for pterygium and CIN during two years. Morphological differences between both lesions were studied with AS-OCT; epithelial thicknesses (EE) and extension length on corneal surface (GIC) were compared between both groups. A surgical excision of the lesion was performed for histopathological diagnosis.

RESULTS

Mean age of patients with pterygium (n=18) was 52.67±15 y.o and 74±12 y.o in subjects with CIN (n=4) (p<0.021). In pterygia, AS-OCT showed typical features (normal, thinning or slightly thickened EE; 77.4±26μm), in addition to an increase in wedge-shaped subepithelial tissue. Patients with CIN had a mean thickened EE (262.5±124μm) and strongly hyperreflective, with abrupt transition between normal and pathological epithelium. Analysis of EE between subjects with pterygium and CIN revealed statistically significant differences (p<0.002). ROC curve revealed a 100% sensitivity and specificity of OCT-SA in differentiation between CIN and pterygium, using 141μm as cutoff point of EE.

CONCLUSION

AS-OCT is a useful tool for the differentiation between pterygium and CIN able to provide typical morphological characteristics. An EE greater than 141μm in AS-OCT suggests a sensitivity and specificity of 100% for the diagnosis of CIN.

Management Issues in Conjunctival Tumours: Ocular Surface Squamous Neoplasia

Ocular surface squamous neoplasia is the most common tumour of the ocular surface. It is a spectrum of disease from intraepithelial dysplasia to invasive squamous cell carcinoma. Recent years have seen an increase in the use of topical chemotherapeutic agents to treat this condition, often as primary treatment without full-thickness biopsy. This practical approach provides a critical appraisal of the evidence base with the goal being to aid the clinician in the management of these patients.

Anterior high-resolution OCT in the diagnosis and management of corneal squamous hyperplasia mimicking a malignancy: a case report

Background

Anterior high-resolution optical coherence tomography (HR-OCT) is a novel non-invasive in vivo imaging modality that can assist in the diagnosis and management of various ophthalmic pathologies. The implementation of diagnosing ocular surface lesions has been explored in previous studies, successfully revealing specific signs in some ocular lesions. This case report aims to exhibit a case of corneal squamous hyperplasia diagnosed via anterior HR-OCT, prior to surgical intervention.

Case presentation

A 69 year-old male had blurred vision and foreign body sensation OD for several weeks. A rapidly-grown corneal mass was presented, showing an appearance of a grayish flesh-colored mass with elastic texture. Large vessels supplying the mass were also found. Anterior HR-OCT was performed, and the results suggested the lesion be benign hyperplasia. Superficial keratectomy was done, and the pathologic report showed mild-appearing epithelial squamous hyperplasia, which confirmed the analysis via anterior HR-OCT.

Conclusion

In the categorization by Nanji, et al. of corneal surface diseases using anterior OCT, the comparative epithelial thickness (normal range: 47—68 μm); inferior border obscuration of epithelium (normal or benign inferior border: no shadowing); reflectivity of epithelial layer (normal: not hyper-reflective); abrupt transition (normal: no horizontally abrupt transition); and sub-epithelium analysis vary between benign and malignant lesions (normal: demarcated anterior to Bowman’s layer), and the differences are systemically sorted. We applied all these characteristics to our patient as guidance, and the measurement results indicated the lesion be a benign lesion, which is consistent with the tissue pathology. Anterior HR-OCT is overall a non-invasive and timely method capable of assisting the diagnosis of ocular surface disease, predicting the qualities of a lesion, and determining the follow-up treatment plan.

Temporal speckle-averaging of optical coherence tomography volumes for in-vivo cellular resolution neuronal and vascular retinal imaging

It has been recently demonstrated that structures corresponding to the cell bodies of highly transparent cells in the retinal ganglion cell layer could be visualized noninvasively in the living human eye by optical coherence tomography (OCT) via temporal averaging. Inspired by this development, we explored the application of volumetric temporal averaging in mice, which are important models for studying human retinal diseases and therapeutic interventions. A general framework of temporal speckle-averaging (TSA) of OCT and optical coherence tomography angiography (OCTA) is presented and applied to mouse retinal volumetric data. Based on the image analysis, the eyes of mice under anesthesia exhibit only minor motions, corresponding to lateral displacements of a few micrometers and rotations of a fraction of 1 deg. Moreover, due to reduced eye movements under anesthesia, there is a negligible amount of motion artifacts within the volumes that need to be corrected to achieve volume coregistration. In addition, the relatively good optical quality of the mouse ocular media allows for cellular-resolution imaging without adaptive optics (AO), greatly simplifying the experimental system, making the proposed framework feasible for large studies. The TSA OCT and TSA OCTA results provide rich information about new structures previously not visualized in living mice with non-AO-OCT. The mechanism of TSA relies on improving signal-to-noise ratio as well as efficient suppression of speckle contrast due to temporal decorrelation of the speckle patterns, enabling full utilization of the high volumetric resolution offered by OCT and OCTA.

Use of High-Resolution Optical Coherence Tomography in the Surgical Management of Ocular Surface Squamous Neoplasia: A Pilot Study

PURPOSE

To evaluate whether high-resolution optical coherence tomography (HR-OCT) can detect histologic tumor margins of ocular surface squamous neoplasia (OSSN).

METHODS

Eight eyes of 8 patients with OSSN undergoing excision were studied prospectively. Immediately before surgery, the tumor was imaged using commercially available HR-OCT to identify the conjunctival margins of the neoplastic lesion. The tumor borders of the lesion determined by HR-OCT were mapped in relation to an anatomic reference point and transferred intraoperatively. The tumor was excised with 4-mm margins from the visible edge of the lesion with a "no-touch" technique. The specimens were sent for pathologic analysis and the histologic tumor margin was compared to the HR-OCT predicted tumor border.

RESULTS

Mean age of the 8 patients was 67 ± 9.9 years. Seven were male, 7 were white, and, ethnically, 3 were Hispanic. All 8 tumors were bulbar and in the exposure zone. Seven tumors were limbal. Corneal extension was present in 5. Mean tumor area was 17.5 ± 11.1 mm². Clinically, 2 of the tumors were leukoplakic, 1 papillomatous, and 3 gelatinous. A conjunctival tumor margin identified with the HR-OCT coincided with the pathologically confirmed margin mark in all eyes.

CONCLUSIONS

HR-OCT has the potential to predict histologic tumor margins in OSSN. Optical identification of tumor margins could potentially decrease the incidence of residual positive margins and minimize healthy tissue removal. Advances in HR-OCT technology and integration into a microscope for "real-time" imaging are needed to further improve this technique. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Utility of high-resolution anterior segment optical coherence tomography in the diagnosis and management of sub-clinical ocular surface squamous neoplasia

Background

To evaluate the frequency and characteristics of sub-clinical ocular surface squamous neoplasia (OSSN) detected by high-resolution anterior segment tomography (HR- OCT) in patients with clinically unapparent disease following topical treatment.

Methods

A retrospective chart review of patients with OSSN identified through a pharmacy database at the Bascom Palmer Eye Institute from January 2013 to December 2018 was conducted. Patients undergoing primary therapy with topical 5-fluorouracil 1% (5-FU) (4 times a day for 7 days with a 21-day break) or interferon-alpha-2b (IFN) (4 times a day) were reviewed. Patients were separated into two groups. Group 1 included individuals whose clinical resolution of OSSN aligned with complete resolution on HR-OCT. Group 2 (sub-clinical OSSN group) included individuals with clinical OSSN resolution but with features of persistent disease on HR- OCT. Patients excluded included those treated at an outside institution and those who used topical therapy as a surgical adjunct.

Results

A total of 95 patients (95 eyes) were reviewed. Sub-clinical OSSN was detected at a frequency of 17% in our study patients (n = 16 patients, 9 treated with 5-FU and 7 treated with IFN). In the 16 individuals, the mean time to clinical resolution was 3.6 ± 1.0 cycles for 5-FU and 4.0 ± 0.0 months for IFN. An additional 2.1 ± 0.8 cycles for 5-FU and 1.2 ± 0.4 months for IFN were needed to achieve HR-OCT resolution of OSSN. Recurrence in Group 1 was noted in 10 patients (12%) while no recurrences occurred in Group 2, the cohort with subclinical disease that received the extended medical therapy. The mean follow-up was 24.0 ± 17.9 months.

Conclusion

We found that at least 17% of individuals with apparent clinical resolution of OSSN have sub-clinical disease detected on HR-OCT. This information can be used to optimize treatment and extend therapy past the point of clinical resolution.